OPTICAL DISPLAY SYSTEM AND METHOD, ACTIVE AND PASSIVE DITHERING USING BIREFRINGENCE, COLOR IMAGE SUPERPOSITIONING AND DISPLAY ENHANCEMENT

Abstract: A passive dithering display system (99) includes an optical display including a plurality of pixels with dead space between the pixels for producing an image, and a birefringent material (10) for shifting one polarization component of the image relative to a second polarization component of the image such that the shifted polarization component lies in the dead space (5b). Thus, the sytem of the invention can change the location of an optical signal, and the change can be used to improve resolution of a display, to reduce fixed pattern noise of a display, to facilitate locating and hiding of circuitry (131), to facilitate overlapping of tiles or pixels, etc.

Description: ΗTLE: OPTICAL DISPLAY SYSTEM AND METHOD, ACTIVE AND PASSIVE DITHERING USING BIREFRINGENCE, COLOR IMAGE SUPERPOSΓΠONING AND DISPLAY ENHANCEMENT This is a continuation-in-part of copending, commonly owned U.S. patent application serial no. 08/398,292, filed March 3, 1995, which is a continuation-in-part of commonly owned U.S. patent application serial No. 08/392,055, filed February 22, 1995, which is a continuation-in-part of copending, commonly owned U.S. patent application serial No. 08/328,375, filed October 25, 1994, the entire disclosures of which hereby are incoφorated by reference. This also is a continuation-in-part of copending, commonly assigned provisional U.S. patent application Serial No. 60/001972, filed July 23, 1995, entitled Display enhancement with phase coordinated polarization switching and method, the entire disclosure of which hereby is incorporated by reference. CROSSREFERENCETORELATED PATENTS ANDPATENTAPPLICATIONS Reference is made to commonly owned co-pending U.S. patent applications Serial No. 08/187,262, 08/187,050, and 08/187,163, filed January 25, 1994; Serial No. 08/275,907, filed July 5, 1994; Serial No. 08/328,375, filed October 25, 1994; Serial No. 08/392,055, filed February 22, 1995; Serial No. 08/398,292, filed March 3, 1995; Serial No. 08/295,383, filed August 24, 1994; Serial No. 08/328,371, filed October 25, 1994; Serial No. 08/383,466, filed February 3, 1995; and provisional patent applications Serial No. 60/002,780 entitled Optical system and method for a head mounted display providing both front and peripheral fields of view and Serial No. 60/002,779 entitled Monocular viewing device with retroreflector display system, telecommunication system, and method, both filed July 19, 1995. The entire disclosures thereof hereby are incorporated by reference. TECHNICAL FIELD The present invention relates generally, as is indicated, to optical display system and method, active and passive dithering using bircftingence, color image superpositioning, and display enhancement with phase coordinated polarization switching. The present invention also relates to dithering systems for optical displays and methods, and, more particularly, to passive dithering systems and methods for changing the location of an optical signal and for improving an optical display. The present invention also relates to the enhancing of optical displays and methods to enhance such displays, and, more particularly, to enhancing optical displays and methods by coordinating the phase of switching light with the dynamic operation of the displayed image developing device. BACKGROUND Dithering systems have been used in a number of technologies in the past. The objective of a dithering system is to change a characteristic of a particular signal in a periodic (or random) fashion in order to provide a useful output. As is described in further detail, the dithering system of the invention may be used to change the relative location of an optical signal. The present invention may be used wim various types of displays and systems. Exemplary displays are a CRT (sometimes referred to herein as cathode ray tube) display, a liquid crystal display (sometimes referred to herein as "LCD"), especially those which modulate light transmitted therethrough, reflective liquid crystal displays, light emitting displays, such as electroluminescent displays, plasma displays and so on. Conventional optical displays typically display graphic visual information, such as computer generated graphics, and pictures generated from video signals, such as from a VCR, from a broadcast television signal, etc.; the pictures may be static or still or they may be moving pictures, as in a movie or in a cartoon, for example. Conventional displays also may present visual information of the alphanumeric type, such as numbers, letters, words, and/or other symbols (whether in the English language or in another language). Visual information viewed by a person (or by a machine or detector) usually is in the form of visible light. Such visible light is referred to as a light signal or an optical signal. The term optical signal with which the invention may be used includes visible light, infrared light, and ultraviolet light, the latter two sometimes being referred to as electromagnetic radiation rather than light. The optical signal may be in the form of a single light ray, a light beam made up of a plurality of light rays, a light signal such as a logic one or a logic zero signal used in an optical computer, for example, or the above-mentioned alphanumeric or graphics type display. Thus, as the invention is described herein, it is useful with optical signals of various types used for various purposes. Therefore, in the present invention reference to optical signal, light ray, light beam, light signal, visual information, etc. , may be used generally equivalently and interchangeably. In an exemplary liquid crystal display sometimes referred to as an image source, there usually are a plurality of picture elements, sometimes referred to as pixels or pels, and these pixels can be selectively operated to produce a visual output in the form of a picture, alphanumeric information, etc. Various techniques are used to provide signals to the pixels. One technique is to use a common electrode on one plate of a liquid crystal cell which forms the display and an active matrix electrode array, such as that formed by thin film transistors (TFT), on the other plate of the liquid crystal cell. Various techniques are used to provide electrical signals to the TFT array to cause a particular type of optical output from respective pixels. Another technique to provide signals to the pixels is to use two arrays of crossed electrodes on respective substrates of an LCD; by applying or not applying a voltage or electric field between a pair of crossed electrodes, a particular optical output can be obtained. One factor in deteπnining resolution of a liquid crystal display is the number of pixels per unit area of the liquid crystal display. For example, Sony Corporation recently announced a 1.35 inch diagonal high resolution liquid crystal display which has 513,000 pixels arranged in 480 rows of 1,068 pixels per row. Another factor affecting resolution is the space between adjacent pixels sometimes referred to "as optical dead space". Such space ordinarily is not useful to produce an optical signal output. The space usually is provided to afford a separation between the adjacent pixels to avoid electrical communication between them. The space also is provided to accommodate circuitry, leads, and various electrical components, such as capacitors, resistors, and even transistors or parts of transistors. The proportion of optical dead space to useful space of pixels that can produce optical output tends to increase as the physical size of the image source is decreased, for the space required to convey electrical signals, for example, may remain approximately constant although the actual size of the useful space of the pixels to produce optical output can be reduced because of anticipated image magnification. However, upon magnification of the image produced by such a miniature image source both the optical dead space and the useful optical space of the pixels are magnified. Thus, resolution tends to be decreased, especially upon such magnification. The picture elements (pixels or pels) may be discrete pixels, blocks or areas where an optical signal can be developed by emission, reflection, transmission, etc. such as the numerous pixels in the miniature image source of Sony Corporation mentioned above. The optical signal referred to may mean that light is "on" or provided as an output from the device, or that the pixel has its other condition of not producing or providing a light output, e.g., "off"; and the optical signal also may be various brightnesses of light or shades of gray. Alternatively, the optical output or optical signal produced by a pixel may be a color or light of a particular color. The pixels may be a plurality of blocks or dots arranged in a number of lines or may be a number of blocks or dots randomly located or grouped in a pattern on the display or image source (source of the optical signal). The pixels may be a number of lines or locations along the raster lines that are scanned in a CRT type device or the pixels may be one or a group of phosphor dots or the like at particular locations, such as along a line in a CRT or other device. The optical signal produced by one or more pixels may be the delivery of light from that pixel or the non-delivery of light from that pixel, or various brightnesses or shades of gray. To obtain operation of a pixel, for example, the pixel may be energized or not. In some devices energizing the pixel may cause the pixel to provide a light output, and in other devices the non- energizing of the pixel may cause the providing of a light output; and the other energized condition may cause the opposite light output condition. It also is possible that the nature of the light output may be dependent on the degree of energization of a pixel, such as by providing the pixel with a relatively low voltage or relatively high voltage to obtain respective optical output signals (on and off or off and on, respectively). For example, in a conventional twisted nematic liquid crystal display device, polarized light 1s received by a liquid crystal cell, and depending on whether the liquid crystal cell receives or does not receive a satisfactory voltage input, the plane of polarization of the light output by the liquid crystal cell will or will not be rotated; and depending on that rotation (or not) and the relative alignment of an output analyzer, light will be transmitted or not. In an optical phase retardation device that has variable birefringence, such as those disclosed in U.S. Patents Nos. 4,385,806, 4,540,243, and RE.32,521 (sometimes referred to as surface mode liquid crystal cells), depending on the optical phase retardation provided by the liquid crystal cell, plane polarized light may be rotated, and the optical output can be determined as a function of the direction of the plane of polarization. In a CRT light emission or not and brightness may be deteπnined by electrons incident on a phosphor at a pixel. In electroluminescent displays and plasma displays light output may be determined by electrical input at respective areas on pixels. The interlacing of raster lines or display lines is a known practice used in television and in other types of display systems. For example, in NTSC and PAL television type cathode ray tube (CRT) displays it is known that two interlaced fields of horizontal lines are used to provide an entire image frame. First one raster or set of lines is scanned to cause one subframe (sometimes referred to as field) to be displayed; and then a second raster or set of lines is scanned to cause a second subframe (field) to be displayed. The electrical signals used to scan one line in one subframe and the electrical signals used to scan the relatively adjacent line of the subsequent subframe may be different, and, therefore, the optical outputs of those lines may be different. The two raster subframes are presented sufficiently fast that the eye of an observer usually cannot distinguish between the respective images of the two successive subframes but rather integrates the two subframes to see a composite image (sometimes referred to as a frame or picture). The two subframes are created sequentially by "writing" the image to respective pixels formed by phosphors to which an electron beam may be directed in response to electrical signals which control the electron beam in on-off and/or intensity manner. After the electron beam has reached the end of its scanning to create one subframe, e.g., the last pixel or phosphor dot area of that field, there is a period of time while the electron beam is moved or directed to the first pixel of the next subframe. During that period of time a blanking pulse is provided to prevent electrons from being directed to phosphors or pixels causing undesired light emission. Sometimes various circuits of a television or CRT display are synchronized to the operative timing of the television, CRT, etc. by synchronization with such blanking pulses. The density of pixels, e.g., number of pixels per unit area, in a CRT display usually is, in a sense, an analog function depending on characteristics of the electron beam, drive and control circuitry for the beam, phosphor dot layout, shadow mask(s), etc., as is known. Usually a CRT is driven using the interlaced lines forming the subframes mentioned above. In an LCD, though, there is a fixed number of pixels per line or row; and data, e.g., whether a given pixel in a row is to transmit light or to block light transmission, usually is written to the pixels a row at a time. The data is written to one row, then to the next, and so on, and there usually is no interlacing of rows or of subframes as there is in CRT driving techniques. In some LCD's the two subframes mentioned above usually are effectively averaged together, when driven by a CRT type of interlaced signal, since there usually is no physical interlacing of LCD pixels to form respective subframes as there are respective scan lines of phosphor dots, for example, in a CRT. Rather, the electrical signals for driving adjacent scan lines of different respective interlaced subframes of a CRT display, both usually are delivered to only ' a single row of pixels in an LCD. Each pixel responds to the electrical signal applied thereto to transmit or to block light, for example. Those two sets of electrical signals are applied to the row of pixels at different times. Therefore, at one time a given row of LCD pixels may present as an optical output optical information from one subframe and at a later time present optical information from the other subframe. Since the optical information presented in one subframe is expected to be displaced in space from the optical information presented in the other subframe to obtain the interlacing pattern of a CRT display, careful examination of the optical output from the above-mentioned LCD will show an amount of "jittering" of the image. This jittering is caused by the pixels of one row periodically being changed so the optical output thereof sequentially displays the result of energization by signals representing one scan line of information from one subframe and then energization by electrical signals representing the adjacent scan line of information from the next subframe. This jittering can degrade the displayed image and can make viewing uncomfortable. Also, the problems, such as viewing discomfort and/or image degrading, caused by jittering tend to increase as the image is enlarged or magnified, e.g., when the image is created by a relatively miniature image source, such as the SONY display mentioned above, and is magnified for direct viewing or for projection by a projector. One technique for reducing the jittering is to use relatively slow liquid crystal display devices. Therefore, the liquid crystal display element or pixel tends to average the electrical signals applied thereto. A disadvantage to this technique, though, is that image resolution is reduced because the information representing two scan lines is combined into a single line. Also, a slow acting liquid crystal display element tends to have undesirable hysteresis that slows motion being shown by the display. In a color display, such as a LCD (liquid crystal display), there usually are red, green and blue pixels which form a color triad (hereinafter referred to as triad). By operating the LCD in such a way that one or more of the pixels forming a triad provides (or produces) the respective color light of that pixel, different respective colors and white can be produced as output light. For example, if the red pixel of a triad were providing red output light; and the green and blue pixels were not providing output light, the light output from that triad would be red. Further, when two or more pixels of a triad are providing light output, a combination of those colors is seen by a person viewing (sometimes referred to as the viewer) the light output or image. The viewer usually visually superimposes the output light from the pixels of the triad; and the combined or superimposed lights therefrom provide the net effect or integrated light output of the triad. As an example, to produce a white light output from a triad, the red, green and blue pixels of that triad would provide, respectively, red, green and blue light; and those lights would be, in effect, superimposed by the viewer and seen as white light. There is a continuing need and/or desire to improve resolution of displays. It also would be desirable to facilitate the placing of circuitry in a display while minimizing the optical dead space caused by the circuitry. There also is a need to reduce jitter. In the above-mentioned patent applications are disclosed techniques for actively dithering, moving an optical signal, changing the location or optical path of an optical signal, etc. for several purposes, such as to increase resolution, to reduce jitter, and so on. There also are disclosed techniques for passive dithering, moving of optical signals, etc., for example to increase the fill factor of an image provided by a display by expanding the image or pixels forming the image. An LCD using the twisted nematic effect usually cannot switch between transmission states as rapidly as changes occur in the applied electrical signal which operates the LCD. For example, the electrical input to a twisted nematic LCD can change nearly instantly, but it takes a number of milliseconds for the LCD to respond dynamically to the change in electrical input to change the optical response of the LCD. When an LCD is used in a display system that employs dithering to double, quadruple or otherwise to change the effective number of pixels, for convenience hereinafter, sometimes referred to as optical line doubling (or OLD), the relatively slow response of the twisted nematic LCD compared to the faster operation of the dithering optics can result in an optical output that does not achieve the desired improvement in resolution or other optical effect. The displaying of a dark scene using a display device (sometimes referred to as a passive display), which modulates light received from a separate light source, encounters a disadvantage which ordinarily is not present for displays which produce their own light, such as a cathode ray tube (CRT). The problem has to do with reduced resolution and/or contrast of the displayed image. In a CRT, for example, when it is desired to display a dark scene, the intensity of the output light can be reduced. The different parts of the dark scene, then, all may be output at the reduced brightness or illuminance level. All pixels (e.g., picture elements, phosphor dots in a monochrome display or group of three red, green and blue phosphor dots for a multicolor display, etc.) of the CRT can be active so that resolution is maintained even though intensity of the light produced by the phosphors is reduced. However, in a passive display device, such as a liquid crystal display, an electrochromic display, etc., whether of the light transmitting type or of the light reflecting type, the usual practice to reduce brightness of a displayed image or scene is to reduce the number of pixels which are transmitting light at a particular moment. Such a reduction reduces the resolution of the display. Also, such a reduction can reduce the contrast of the display. The human eye has difficulty distinguishing between seeing or recognizing the difference between low and high brightness and contrast ranges. This difficulty is increased when the number of pixels is decreased and resolution is degraded. It would be desirable to improve the contrast and resolution of passive displays. In U.S. patent application Serial No. 08/187,163 is disclosed a passive apparatus, such as an LCD, and method for displaying images with high contrast by controlling the light input to the display to control brightness of the output while operating respective pixels of the display to obtain good contrast substantially without regard to the output brightness. Different color effects also are disclosed using, for example, field sequential switching of respective color light. However, this is another example of a passive optical device, in this case an LCD, in which field sequential switching could be improved if coordinated with the delays inherent in the dynamic optical response of a liquid crystal cell, for example, relative to the changes in operating signal, such as electric field, voltage, etc. As is described in application Serial No. 08/187,163, an image of a candlelit room would be dim. In the prior art devices a relatively small number of pixels would be used, then, to transmit light to create the image, whereas a relatively large number of pixels would be used to block light transmission to give the effect of the reduced intensity or dim room. In the invention of such application, though, the number of pixels used to create the image remains constant, and the contrast ratio between one portion and another portion of the image remain constant; only the intensity of the illuminating light changes thereby to diminish the brightness of the room. Therefore, with the invention image data is not lost regardless of the brightness of the image, whereas in the prior art image data is lost because the additional pixels are used to brighten or darken the brightness of the image. The features of the invention as described in that patent application can be used in a frame sequential basis. The features of the invention can be used regardless of whether the display is operated in reflective mode or in transmissive mode. Also, the features of the invention can be used in a virtual reality type display in order to provide a very wide range of contrast and of image brightness characteristics. The picture information is used to derive the brightness of the display, not the surrounding ambient. Using the invention of that application, the amount of information that can be conveyed by the display is substantially increased over the prior art. For example, if there were a grey scale of 100 shades of grey and a display with 10 shades of grey, the intensity of the illuminating source can be changed at 10 different levels, for example, and there also can be 10 different shades of grey provided by the display itself. Therefore, this provides 100 shades of grey. This characteristic can be increased by another factor of 10 by going to r, g, b (red, green, blue) modulation on a field sequential basis, which allows the possibility of 10 to the 6th different illumination levels and colors. The foregoing is especially important in head mounted displays where immersion in the image is extremely important. Using features of such patent application, there can be high illumination of the seam, then, the grey scale contrast ratio of the reel image can be adjusted. As a result, there is a high contrast image presented in a bright motif. Another example using such invention is the ability to display a sunrise scene in which the red image is enhanced and the blue and green are minimized. The invention of that application, then, can separate the two functions of brightness and image. The image is a function of the operation of the liquid crystal modulator and the illumination brightness is the function of the light source intensity. The r, g, b colors can be changed to give a candlelight or moonlight effect with good resolution and color function, but the brightness of the scene is a function of the background. As a result, it is possible to photograph the scene in daylight to get good contrast; and then by reducing the display illumination it is possible to give the impression of a moonlit or candlelit environment. SUMMARY With the foregoing in mind, then, one aspect of the invention is to increase the resolution of a display by electro-optically dithering an optical signal. Another aspect relates to use of electro-optical dithering to obtain three dimensional images, especially using auto-stereoscopic effect. Another aspect relates to using electro-optical ditnering to effect beam switching of optical signals. Another aspect is electro-optically to change selectively the location at which an optical output signal is presented to another location. A further aspect is to effect such change in more than one direction, e.g., along more then one axis. According to another aspect, a device for changing or determining the location of an optical signal includes birefringent means for selectively refracting light based on optical polarization characteristic of the light, and means for changing such optical polarization characteristic of light, the birefringent means and the changing means being cooperative selectively to change the location of the optical signal. According to another aspect, a system for increasing the resolution of an optical display having a plurality of picture elements includes birefringent means for selectively refracting light based on polarization characteristics of the light, changing means for selectively changing the polarization characteristics of light, and the birefringent means and the changing means being in optical series and cooperative in response to selective operation of the changing means to change the location of output optical signals therefrom. According to another aspect, a display system includes a display for producing visual output information by selective operation of a plurality of picture elements at respective locations, and means for changing the location of the output information as a function of optical polarization thereby effectively to increase the number of picture elements. According to another aspect, a display system includes a display for producing visual output information by selective operation of a plurality of picture elements at respective locations, and means for changing the location of the output information without physical realignment of a mechanical device thereby effectively to increase the number of picture elements. According to another aspect, a display system includes a display for producing visual output information by selective operation of a plurality of picture elements at respective locations, and means for electro-optically changing the location of the output information thereby effectively to increase the number of picture elements. According to another aspect, a method for displaying visual information includes presenting a first optical output from a source by providing plural optical signals arranged in a pattern, presenting a second optical ouφut from the source by providing plural optical signals arranged in a pattern, and selectively shifting the location of the pattern of the second optical ouφut relative to the location of the patten of the first optical ouφut based on optical polarization. According to another aspect, an electro-optical dithering system for shifting polarized light includes birefringent means for selectively refracting light as a function of a polarization characteristic of the light, and changing means for changing the polarization characteristic of polarized light to provide ouφut light that is shifted or not as a function of optical polarization. According to another aspect, a method of making a display includes positioning in optical series an image source, a birefringent means for selectively refracting light based on optical polarization characteristic of the light, and a changing means for changing such optical polarization characteristic. Using principles of the invention, the location of an optical signal can be changed, and the change can be used for a number of purposes. For example, the change can be used to improve resolution of a display, to provide an auto-stereoscopic ouφut, to interlace optical signals, to facilitate positioning and hiding of circuitry used in a display, to facilitate overlapping of tiles or pixels in a display, etc. A number of these examples are presented below. The invention may be used to achieve one or more of those and other uses. An aspect of the invention relates to an optical line increaser, wherein the number of pixels in a optical display can be increased by electro-optical means. An aspect of the invention relates to an optical line increaser, wherein the number of pixels in a optical display can be increased by electro-optical means, for example, to double, triple, quadruple, or otherwise to increase the effective number of pixels presenting ouφut optical information for viewing by a person, machine, other device, etc., and/or for other use. Another aspect is to hide or to reduce optical dead space in a display. Another aspect is to use a switchable electro-optical device to effect dithering (changing effective location) of an optical signal. Another aspect is to reduce jitter in an optical display. Another aspect is to drive a non-interlaced display using an interlaced signal and electro-optically dithering the optical ouφut of the display to reduce jitter. Another aspect is to increase the effective number of pixels and/or lines of an optical display. In accordance with a further aspect of the invention, a passive dithering display system includes an optical display including a plurality of pixels with optical dead space between the pixels for producing an image, and a birefringent material for shifting one polarization component of the image relative to a second polarization component of the image such that the shifted polarization component lies in the dead space. In accordance with another aspect, a display system includes an optical display for producing an image and a first birefringent material for refracting one component of the image relative to a second component of the image based on polarization characteristics of the components to produce a plurality of adjacent images. In accordance with a still further aspect of the invention, a method of reducing optical background noise includes the steps of displaying a plurality of pixels with optical dead space between said pixels for producing an image and shifting one polarization component of the image relative to a second polarization component of the image such that the shifted polarization component lies in the dead space. Another aspect relates to expanding an image or pixels of an image to increase the fill factor of the image, the fill factor relating to the amount of area of the image actually occupied by image compared to that part of the image occupied by optical dead space. Another aspect relates to using passive image or pixel expanding to increase the fill factor of an image. Another aspect relates to using active image or pixel doubling (or other increasing) to increase fill factor and resolution of an image. Another aspect relates to techniques to superimpose color pixel image light ouφuts to obtain respective color ouφuts for a display. Another aspect is to increase the amount of data able to be displayed from a video signal or the like provided to a display system, such as an LCD display system or other display system. As is described further below, The invention is useful to coordinate light ouφut by an optical device, such as an LCD, for example, and the dynamic operation of such optical device with another optical device, such as one that switches or shifts the location of the ouφut light for use, such as viewing, projection, etc., one that displays images in field (sometimes referred to as frame or part of a frame) sequential operation to present images with good contrast and/or color effect that are independent of the brightness of the ouφut light, and so on. One or more of these and other objects, features and advantages of the present invention are accomplished using the invention described and claimed below. To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Although the invention is shown and described with respect to certain preferred embodiments, it is obvious that equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the claims. Brief Description of the Drawings In the annexed drawings: Fig. 1 is a schematic side elevation view of a CRT display including an electro- optical dithering system according to the present invention; Fig. 2 is a schematic illustration of the components of the electro-optical dithering system of Fig. 1; Fig. 3 is a schematic illustration of the double refraction effect through a calcite crystal which may be used in the electro-optical dithering system of the invention; Figs. 4A, 4B and 4C are, respectively, schematic illustrations indicating exemplary axial alignment of the several components of the electro-optical dithering system shown in Fig. 2; Figs. 5A, 5B and 5C are, respectively, schematic illustrations similar to Fig. 2 showing the operation of the electro-optical dithering system on light in respective operational modes; Fig. 6 is a schematic illustration of an alternate embodiment of electro-optical dithering system; Fig. 7 is a schematic front view of the face or display ouφut of a CRT showing exemplary raster lines; Fig. 8 is a schematic side elevation view of the electro-optical dithering system of the invention used in an auto-stereoscopic display; Fig. 9 is an enlarged view of a single lens element of the auto-stereoscopic display of Fig. 8; Fig. 10 is a schematic plan view of part of a liquid crystal display showing areas where pixels are located and areas where there is circuity or dead space located between adjacent pixels and including the electro-optical dithering system of the invention; Fig. 11 is a schematic top view of the display of Fig. 10 showing the paths of optical signals that are shifted in location according to the on or off state of the electro- optical dithering system of the display; Figs. 12 and 13 are schematic block diagrams of synchronizing circuit techniques useful in the various display systems of the invention; Figs. 14 and 15A-15E are schematic illustrations of a display system and parts thereof with a double electro-optical dithering system; Figs. 16A-16D are schematic illustrations of a pixel pattern that is dithered or not in up to four different spatial pattern locations; Fig. 17 is a composite of the pixel patterns of Figs. 16A-16D; Figs. 18 and 19 are schematic illustrations of a display system with a double electro-optical dithering system and parts thereof using switchable liquid crystal birefringent devices; Fig. 20 is a schematic illustration of part of a red, green and blue pixel arrangement for a multicolor display; Fig. 21 is a schematic illustration of a segmented display system with selective time sequenced dithering of respective segments; Figs. 22A-22F are schematic illustrations of the segmented display system of Fig. 21 showing the time sequence of operation thereof; Fig. 23 is a schematic illustration of a passive dithering system used in connection with a display which produces a polarized ouφut; Fig. 24 is a schematic illustration of the effect of dithering in both horizontal and vertical directions; Fig. 25 is a schematic illustration of the orientations of the optic axes of the components of the passive dithering system of Fig. 23; Fig. 26 is a schematic illustration of the passive dithering system of Fig. 23 used in connection with a display which produces a nonpolarized (sometimes referred to as unpolarized) light ouφut; Fig. 27 is a schematic illustration of the orientations of the optic axes of the components of the passive dithering system of Fig. 26; Fig. 28 is a schematic illustration of an alternate embodiment of a passive dithering system; Fig. 29 is a schematic illustration of the orientations of the optic axes of the components of the passive dithering system of Fig. 28; Fig. 30 is a schematic illustration of the passive dithering system of Fig. 28 used in connection with a display which produces a nonpolarized light ouφut; Fig. 31 is a schematic illustration of an optical display system using an alternate embodiment of a passive dithering system using unpolarized light input; Fig. 32 is a schematic illustration of the orientations of the optic axes of the components of the passive dithering system of Fig. 31; Fig. 33 is a schematic illustration of an alternate embodiment of optical display system using an active dithering system for diagonally displacing a pixel image; Fig. 34 is a schematic illustration of the locations of the original pixel images unshifted and of the shifted pixel images using the dithering system of Fig. 33; Fig. 35 is a schematic illustration of an alternate embodiment of optical display system using active and passive dithering system for displacing pixel images; Fig. 36 is a schematic illustration of the locations of the original pixel images unshifted and of the shifted pixel images using the dithering system of Fig. 35 in four respective operations; Fig. 37 is a schematic illustration of the display ouφut from an optical display system of the type shown in Fig. 35, for example, showing shifting of pixel images relative to each other to obtain superpositioning of color pixel images and increased fill factor; Figs. 38 and 39 are schematic illustrations of display ouφuts from an optical display system of the type shown in Fig. 35 and or in other figures hereof, for example, showing shifting of pixel images into gaps between pixels and in overlapping relative to each other; Fig. 40 is a schematic illustration of the display ouφut from an optical display system of the type shown in Fig. 41, for example, showing shifting of pixel images according to an exemplary prescribed pattern; Fig. 41 is a schematic illustration of an optical display system including the components to obtain the operation depicted in Fig. 40 for a head mounted or boom mounted display system or other display system; Fig. 42 is a schematic illustration of a display system in accordance with an embodiment of the invention including a head mounted portion; Fig. 43 is a schematic section elevation view showing the various operational parts of the monocular viewing device used in the display system of Fig. 1; Fig. 44 is a compilation of graphs representing the response of a twisted nematic LCD display pixel when addressed at 60 Hz (Hertz); Fig. 45 is a compilation of graphs representing the response of a twisted nematic LCD display pixel when addressed at 120 Hz; Fig. 46 is a compilation of graphs representing the response of a surface mode type birefringent liquid crystal light shutter operating as an optical rotator or switch coordinated with the operation of a twisted nematic LCD display pixel which is addressed at 120 Hz; Fig. 47 is a schematic illustration of a display optical system used in the viewing device of Figs. 42-43, for example, and/or in other viewing devices or display systems disclosed herein; Fig. 48 is a compilation of graphs showing the relationship of tuning signals for an optical line doubler system that provides both horizontal and vertical doubling (e.g., quadrupling of respective pixels), for example, as in the embodiment depicted in Figs. 14-17; Fig. 49 is a schematic illustration of a light transmissive display system according to an embodiment of the invention; Fig. 50 is a schematic illustration of a light reflective display system according to an embodiment of the invention; Fig. 51 is a schematic view of a reflective field sequential display and illumination system using plural cholesteric liquid crystal reflectors and plural light sources of respective colors to provide a multicolor or full color display useful in various embodiments of the invention; Fig. 52 is a schematic view of a head mounted display system including a pair of display subsystems in accordance with various embodiments of the invention; and Figs. 53-58 are schematic graphical illustrations depicting operation of the invention. DESCRIPTION Referring, now in detail to the drawings wherein like reference numerals designate like parts in the several figures and initially to Fig. 1, an electro-optical dithering system in accordance with an embodiment of the present invention is generally indicated at 1 in use with a display 2 to form an optical display system 3 for providing optical signals, visual information, etc. , as the ouφut therefrom. The display 2 provides a source of light or optical signals, and such light is transmitted through the electro-optical dithering system to provide optical signals at respective locations for viewing or the like. Exemplary light is represented by an arrow 4, such as an optical signal produced at a particular location by the display 2 or produced by some other source and modulated by the display 2 as the ouφut therefrom. The location of the ouφut optical signal 5 is represented by arrows 5a, 5b. Those arrows 5a, 5b represent the location of the ouφut optical signal 5 resulting from the optical signal 4 being transmitted through the electro-optical dithering system 1 while the electro-optical dithering system is in a respective one or the other of the operative states thereof, such as off or on. In the embodiment illustrated in Fig. 1 the display 2 is a CRT. It will be appreciated that the display 2 may be an LCD or another display, such as an electroluminescent display, plasma display, flat panel display or other display. Dithering may refer to the physical displacement of an image. An electro- optical dithering system (EDS) refers to an electro-optical means to physically shift, translate or to change the location of an optical signal, such as an image. The image may be shifted along an axis from one location to another and then back to the first, e.g. up and then down, left and then right, etc. The optical signal may be moved in another direction along a straight or other axis or not along an axis at all. The dithering may be repetitive or periodic or it may be asynchronous in moving an image from one location to another and then holding it there, at least for a set or non- predetermined time. The electro-optical dithering system 1, as it is shown in Fig. 1, includes birefringent material, which sometimes is referred to as double refracting material, 10. An example of birefringent material is a calcite crystal material. Other double refracting (birefringent) materials also may be used. Birefringent material may transmit light straight through or may refract the light which is incident thereon, depending on a characteristic of the light incident thereon, such as optical polarization characteristic. In the illustrated embodiment the optical polarization characteristic is the direction of the electric vector of plane polarized light. Plane polarized light having one direction of electric vector (sometimes referred to as direction of the polarization axis, the transmission axis of the polarizer or of the light, the plane of polarization of the light, the direction of polarization, etc.) may transmit directly through the birefringent material 10 without being refracted or bent, whereas light having a different direction of plane of polarization may be refracted (bent) by the birefringent material 10. For example, plane polarized light which encounters one index of refraction characteristic, such as an ordinary index of refraction characteristic, of the birefringent material may be transmitted without refraction. However, plane polarized light which encounters a different index of refraction characteristic, such as the extraordinary index of refraction, of the birefringent material will bend or refract at the interface with the birefringent material, both upon entering and upon leaving the birefringent material. Therefore, in a sense the birefringent material 10 changes the direction of light transmitted through it, for example, as it changes the location of the ouφut optical signal from location 5a to 5b. In the optical display system 3 embodiment illustrated in Fig. 1 the electro- optical dithering system 1 also includes a switch 11 that can be operated to change the characteristic of light relevant to the birefringent material 10 to change the location of the ouφut optical signal. In the exemplary embodiment of Fig. 1 refraction of light or transmission of light without refraction by the birefringent material 10 depends on the direction of polarization of plane polarized light incident on the birefringent material 10, and the switch 11 is able to switch the direction of polarization of such light incident on the birefringent material 10. In the embodiment illustrated in Fig. 1 the switch 11 is a liquid crystal cell or liquid crystal shutter type device which is able to transmit light to the birefringent material 10 such that the light incident on the birefringent material has a plane of polarization that can be changed by the switch. Accordingly, if the switch is in one operative state or mode, the light incident on the birefringent material 10 may have a plane of polarization such that the ouφut optical signal 5 occurs at e location of the arrow 5a, and wit the switch 11 in a different state of energization the plane of polarization of the light incident on the birefringent material 10 can be changed (e.g., switched to an orthogonal direction to the first-mentioned plane) thereby to cause the ouφut optical signal to occur at the location of the arrow 5b. A linear polarizer (sometimes referred to as a plane polarizer) 12 is between the switch 11 and the CRT display 2. The light 4 provided by the display 2 is plane polarized by the polarizer 12. The direction of polarization in cooperation with one condition of the switch 11 will result in the light being transmitted directly through the birefringent material 10 without refraction so as to appear at location of arrow 5a. However, in response to the other condition of the switch 11 , the light will be refracted by the birefringent material 10 so as to occur at the location of the arrow 5b. With the foregoing in mind, then, it will be appreciated that the invention includes a material that can move the location of an ouφut optical signal relative to the location of an incident (input) optical signal depending on a characteristic of the incident optical signal, such as the direction of plane polarized light. The electro- optical dithering system 1 of the invention includes birefringent, double refracting, or equivalent material and a means to switch or to discriminate the characteristic of the incident optical signal. In the embodiment illustrated in Fig. 1, the light 4 from a CRT is unpolarized. The polarizer 12 gives the light a characteristic of linear (plane) polarization. The switch 11 can change the direction of polarization, e.g., the direction of the electric vector of the polarized light. The birefringent material provides the ouφut optical signal at the location 5a, 5b, depending on the characteristic of the light incident on the birefringent material. The switch 11 may be a liquid crystal cell or several liquid crystal cells, such as twisted nematic liquid crystal cells, birefringent liquid crystal cells, such as those disclosed in U.S. Patents Nos. 4,385,806, RE.32,521, and 4,540,243, the entire disclosures of which hereby are incorporated by reference. If desired, the liquid crystal cells may be arranged in optical series and operated as a push-pull arrangement to improve linearity of response, and/or for other purposes, for example, as is disclosed in one or more of the aforementioned patents. Other types of liquid crystal cells also may be used for the switch 11. Further, other types of devices that are able to switch the optical characteristic of light, such as the direction of plane polarization, etc., may be used for the switch 11; several examples include ferro-electric liquid crystal cells, variable optical retarders, PLZT devices, and so on. An advantage to using a liquid crystal display (LCD) as the display 2 with the dithering system 1 is that the ouφut light from an LCD usually already may have a characteristic of optical polarization, such as linear polarization. In such a case, the linear polarization characteristic provided by such displays may eliminate the need for a separate linear polarizer 12. In Fig. 2 the electro-optical dithering system 1 is shown in use in an optical display system 13 having a transmissive LCD 20. The LCD 20 may be a twisted nematic liquid crystal display, birefringent liquid crystal display, or some other type of liquid crystal display which produces in response to input light 21 from a light source 22, ouφut light represented by an arrow 23. The LCD 20 may be transmissive or reflective. The ouφut light 23 may be, for example, a graphic image, one or more light beams that are selectively turned on or off depending on operation of the liquid crystal display 20, etc. The graphic image may be a moving image, an alphanumeric display, etc. The dithering system 1 includes a birefringent material 10 and a switch 11. To simplify the following description, the switch 11 may be referred to as a polarization rotator, which rotates the plane of polarization of the light represented by arrow 23 an amount depending upon the energization state or condition of the polarization rotator. For example, if the switch 11 were a twisted nematic liquid crystal cell, when it is de-energized, it would rotate the plane of polarization by 90 degrees (or some other amount depending on the nature of the liquid crystal cell), and when the twisted nematic liquid crystal cell is in a fully energized condition, it would not rotate the plane of polarization of the light incident thereon. Similar operation could be obtained by using birefringent liquid crystal cells. Additionally, if desired, compensation may be provided for residual retardation in a liquid crystal cell, whether of the birefringent or twisted nematic type; such compensation may be provided by a wave plate or the like, such as a quarter wave plate positioned in a particular orientation relative to the rub direction or axis of the liquid crystal cell used in the switch 11. Further, a wave plate, such as a half wave plate, may be used to rotate the plane of polarization of light 23 so it is appropriately aligned with the optic axis (sometimes referred to herein as the rub direction, optical axis, or simply axis) of the switch 11. For example, if the switch 11 were a twisted nematic liquid crystal cell, the plane of polarization of the light 23 may be parallel or perpendicular to the rub direction of one of the plates of the liquid crystal cell. If the switch 11 were a birefringent liquid crystal cell, such as a surface mode cell or a pi-cell (e.g., as the above-mentioned patents or in U.S. patent No. 4,582,396, which is hereby incorporated by reference), the plane of polarization of light 23 may be at 45 degrees to the rub direction. In using a half wave plate to adjust plane of polarization, for example, the axis of the half wave plate would be aligned to one half the angular distance between the orientation of the plane of polarization of the light incident on the half wave plate and the angular orientation desired for the light ouφut from the half wave plate. Turning to Fig. 3, there is shown an example of birefringent material 10 in the form of the mineral calcite, also referred to as a calcite crystal 30. Unpolarized light 31 enters the calcite 30 at the left hand face 32 thereof. The light enters at a right angle to the face 32. The light 31 is resolved into two orthogonally polarized components 33, 34 in view of the birefringent nature of the calcite. The optical axis of the light components 33, 34 are oriented such that one component 33 has a plane of polarization or electric vector direction into and out of the plane of the drawing of Fig. 3, as is represented by the dots shown in Fig. 3, and such light 33 experiences an index of refraction change between the environment 35 outside the calcite 30 and the environment 36 inside the calcite 30. However, the axis of the calcite crystal 30 is at a right angle to the plane of polarization to the light 33 , and, therefore, this components of light 33 travels through the calcite crystal 30 without deflection (refraction); sometimes this light is referred to herein as the undithered light. The light component 34 is polarized vertically in the plane of the drawing of Fig. 3 and is represented by a double-headed arrow in the drawing. The light component 34 experiences a change in index of refraction as above; however, the light component 34 also encounters the calcite crystal axis at an angle which is other than a right angle. Therefore, the light component 34 is refracted and its path is deflected (direction is changed) as it enters and leaves the crystal on its travel through the crystal 30, as is shown in Fig. 3; sometimes this light is referred to herein as the dithered light. This property of refraction of one polarization component and no refraction of the other polarization component of light incident on a birefringent material sometimes is called double refraction, and it occurs in many materials. The amount of physical displacement between the light components 33, 34 where they exit the right hand face 37 of the calcite crystal 30 and become, respectively, ouφut light 33a, 34a represented by arrows at locations 38a, 38b, respectively, depends on the thickness of the calcite crystal, indices of refraction of the calcite crystal and the external environment thereof, and the orientation of the optical axis of the specific material, as is known. In the optical display system 3 of Fig. 1 in which the display 2 is a CRT and in the optical display system 13 of Fig. 2 which uses an LCD 20 the direction of polarization of light incident on the switch 11 and the orientation of the switch 11 may be related for optimal operation. In one example of the invention, the switch 11 is a birefringent liquid crystal cell (or a pair of them operating in push-pull manner), and such liquid crystal cell(s) has (have) an axis which sometimes is referred to as the rub direction, alignment direction, optic or optical axis, etc. of the liquid crystal cell. Using such a liquid crystal cell in the systems 3 or 13, for optimal operation the polarization direction (transmission direction axis of the polarizer 12 or of the LCD 20, for example) should be at 45 degrees relative to the axis of the switch 11. Additionally, preferably the projection of the axis of die calcite crystal 30 is oriented at 45 degrees to the axis of the switch 11. These relationships are depicted in Figs. 4A, 4B and 4C. Briefly referring to Figs. 4A, 4B and 4C, the above-described relationships of axes is shown. In Fig. 4 A the transmission axis of the polarizer 12 or d e plane of polarization of light delivered by the liquid crystal display 20 or by CRT 2 and polarizer 12 is shown as horizontal at 40. However, such direction also may be vertical, because it is desired that die relationship between that axis and the axis of die liquid crystal cell(s) of the birefringent liquid crystal cell switch 11 be at a relative 45 degrees thereto. Such 45 degrees relationship is shown by the respective axes 41, 42 for the switch 11. In fact, such axes 41, 42 may represent the axis of one liquid crystal cell and the axis of a second liquid crystal cell, the two being arranged in optical series and being operated in push-pull fashion. The axes 43, 44 of die calcite crystal 30 are shown as horizontal and vertical. However, the vertical axis actually is tipped in or out of the plane of the drawing and it actually is the projection of diat axes which would appear as vertical; alternatively or additionally the horizontal axis may be tipped. Such projection of the axes preferably is at 45 degrees to the axes 41, 42 of the switch 11. The described relative orientation of d e axes of the various components used in connection with the invention is exemplary, and it will be appreciated that otiier arrangements may be used to obtain a particular type of operation. However, in the ideal simplified case described herein, the relationship described may be employed. Also, it will be appreciated that compensation may be provided to adjust the effective orientation of a particular axis. Such compensation can be provided using a birefringent material, a wave plate, such as a quarter wave plate or another one, etc., as was mentioned above. It will be appreciated that whether the axis of a birefringent switch 11 is at plus or minus 45 degrees, represented by the axis lines 41, 42, for example, and whether a respective axis 43, 44 of the calcite 30 or other double refracting material 10 is at plus or minus 45 degrees to the axis of d e birefringent switch (and parallel or perpendicular to the plane of polarization 40) will determine whether the dimered optical signal will be moved up, down, left or right relative to die undithered signal. If me switch 11 were a twisted nematic liquid crystal cell, me axis 40 may be parallel or perpendicular to one of the axes of the liquid crystal cell, and the orientation of the calcite 30 may be as shown in Fig 4C relative to the plane of polarization of the light represented at 40 in Fig. 4A. It will be appreciated that the arrangement of axes herein described are exemplary. The alignment of the switch 11 , whatever that component is comprised of, preferably is such that the switch is able to change a characteristic of light in the display system 3, 13 (and others described herein, for example) so that selective dithering can be carried out by a double refraction or other functionally equivalent material or device. Orientation of the double refracting material may be such as to cause such selective dithering depending on an optical characteristic of the light, which is incident thereon and/or is transmitted therethrough, relative to the double refracting material. Quarter wave plates, other wave plates, etc. may be used in conjunction with coupling of light along optical paths used in the electro-optical dithering system 1 and/or me optical display systems 3 or 13, etc. Also, such wave plates may be used to convert plane polarized light to circularly polarize light or vice versa, depending on the nature of the optical coupling occurring in the various components and optical paths and/or the switch 11 used in the invention. Referring to Figs. 5A, 5B and 5C, operation of d e EDS 1 according to the invention is depicted for use in the exemplary systems 3, 13, etc., which are expressly described herein, and in odier display systems, too. Light 4, for example, from a CRT, is horizontally polarized by die polarizer 12. Arrow 50 represents such horizonal polarization, as does the dot in that arrow 50. The switch 11 is a birefringent liquid crystal cell of d e type disclosed in the above-mentioned patents (such types sometimes being referred to as "surface mode" or "pi-cell" liquid crystal devices). When the switch 11 is in the high voltage state it does not affect the state of polarization of the light 50. Therefore, light 51 exiting the switch 11 also has horizontal polarization, e.g., into and out of the plane of the paper of the drawing. The light 51 enters the double refracting material (birefringent material) 10 and is transmitted without any deflection and is provided as ouφut light 52 at the location and in the direction of arrow 5a. Referring to Fig. 5B, when the switch 11 is in the low voltage state, it rotates the plane of polarization of the light 50 preferably 90 degrees, i.e., into the vertical plane, as is shown by die vertical arrow 53 associated wiu the light 51. The vertically polarized light enters the double refracting material 10 and its padi is physically displaced, as is represented by dashed line 54 resulting in ouφut light 52 at the location and in the direction of the arrow 5b. Briefly referring to Fig. 5C, the electro-optical didiering system 1 is shown having the light ouφut 52 selectively switched between die location of die arrows 5a when the switch 11 is in die high voltage (no rotation of plane of polarization) state and the location of the arrow 5b, which occurs when the switch 11 is in the low voltage (polarization rotating) state. The light represented by arrow 5a is horizontally polarized, and the light represented by die arrow 5b is vertically polarized, as is represented in die drawing of Fig. 5C. By selectively energizing and de-energizing or, in any event, operating me switch 11 between two mentioned voltage states, which switch the polarization characteristic of the light, die location of die ouφut optical signal 52 can be switched between die locations represented by arrows 5a and 5b. A modified optical display system 60 is shown in Fig. 6 using an electro-optical dithering system 1, as was described above, in combination wi an ouφut polarizer (analyzer) 12'. The analyzer 12' may be a linear (plane) polarizer or some other device which can discriminate between me characteristics of light incident therein, such as the direction of plane of polarization, circular polarization, etc. The parts of the electro-optical didiering system 1 include a birefringent material 10, such as a calcite material described above, and a switch 11, such as one of me liquid crystal cell devices described above, or some omer device, as will be appreciated. The incident light 4 is received from a light source or image source, such as a CRT 2 or some other device that delivers unpolarized light ouφut. Such unpolarized light 4 incident on me birefringent material 10 is divided into two components 61, 62. The light component 61 is horizontally polarized and it is transmitted directly through d e birefringent material 10 without deflection or refraction. The light component 62 is polarized in the vertical direction, and it is refracted so that its direction is changed (path is deflected) in die manner shown representatively in Fig. 6. It will be appreciated that here and elsewhere in this description reference to directions is meant to be relative and exemplary; for example, horizontal and vertical are meant to indicate orthogonal relationship. Directions are exemplary and are used to facilitate description and understanding of die invention. The horizontally polarized light component 61 and the vertically polarized light component 62, the directions of polarization being represented by die dots 63 and d e arrow 64, respectively, are incident on the switch 11. From die switch 11 the light components 61, 62 are incident on the analyzer 12'. That light component which has a polarization direction that is parallel to the transmission axis of the analyzer 12' will be transmitted through the analyzer, and the other light component will be blocked. Depending on whether d e switch 11 is in die operative state to transmit light without rotation of the plane of polarization or is in the operative mode to rotate the plane of polarization of the light transmitted therethrough, one or the other of the light components 61, 62 will be transmitted through the analyzer 12' at a respective location represented by one of the arrows 5a, 5b. An exemplary use of the invention is illustrated in Fig. 7 for the CRT display 2 or for a liquid crystal display 20, for example. The display 2, 20 has a resolution of some fixed number of raster lines or rows of pixels that are updated periodically, for example, 60 times per second. Assume that the speed of die display is increased, for example, is doubled to 120 times per second to re-scan the raster lines and/or die rows of pixels. The switch 11 can be synchronized with the switching of the display (CRT 2 or liquid crystal display 20) such that the raster images, for example, are alternately displaced and not displaced, e.g., to locations 5a and 5b, respectively. Such synchronization may be with respect to the blanking pulse or some other signal. The amount of such shifting or displacement can be adjusted as aforesaid so that me displaced raster lines (or pixel rows) interdigitate die non-displaced raster lines (pixel rows). The information on the displaced and non-displaced rasters (pixel rows) are selected to carry complementary information; and, erefore, the resolution of die entire image displayed by the optical display system 3 or 13 is increased by a factor of 2. The same technique can be used to provide image coverage over die dead space between adjacent pixels in a liquid crystal display (or in a CRT, e.g., where a shadow mask blocks transmission of electrons) or to cover areas where conductors or odier electrical connections or components of a liquid crystal display, such as parts of an active matrix array, are located, usually between adjacent pixels. The display ordinarily would be refreshed or updated 60 times per second to cover bom die odd and even raster lines. However, by increasing the refresh or update rate to 120 times per second and using the electro-optical didiering system to shift the location of the ouφut image or optical signal for part of the time, essentially the odd and even raster lines, while unshifted, can be refreshed or updated 60 times per second and the odd and even raster lines, while shifted, can be refreshed or updated 60 times per second. The update or refresh times or rates presented here are exemplary; others may be used. In Fig. 7, assuming the display 2 is a CRT, the front face 70 has a plurality of odd raster lines and a plurality of even raster lines. During operation of the CRT display 2, initially the odd raster lines are scanned to produce a first subframe (field). Subsequently, die even raster lines are scanned, and a second subframe (field) is produced. The information produced during the respective first and second subframes is referred to as complementary and together complete an image (sometimes referred to as a frame or picture) that is viewed. The time between producing one subframe and me next is sufficiendy fast that the eye of an observer (viewer) integrates die respective first and second subframe images to see one complete (composite) image. Similarly, using the principles of the present invention, the space between adjacent raster lines can in effect be scanned to produce additional complementary image information. Thus, for example, the odd lines can be scanned during the first subframe; the even lines can be scanned during the second subframe; the odd lines can be scanned during a third subframe but during which the switch 11 of die electro-optical dithering system 1 is operative to cause shifting of me image to die space between respective adjacent pairs of odd and even raster lines; and finally during a fourth subframe analogous to the d ird, the even raster lines can be scanned while die electro-optical dithering system provides a shift of optical ouφut, to produce the shifted image between respective pairs of odd and even raster lines. In this way resolution of me ouφut image produced by die optical display system 3 is increased without having to increase the resolution or space between relatively adjacent raster lines (scan lines) of die CRT display 2 and a similar technique can be used to increase the effective number of the pixels, pixel rows, etc. to increase resolution of die liquid crystal display 20. Turning to Figs. 8 and 9, an auto-stereoscopic display system 80 is shown using the electro-optical didiering system 1 of the invention. The principles of auto- stereoscopic display are well known and will not be described in detail here. However, d e technique of obtaining the auto-stereoscopic display effect will be described. In the auto-stereoscopic display 80, there is a CRT display 2, which provides a light ouφut 4, which is delivered to a linear polarizer 12. The plane polarized light from the linear polarizer 12 is provided to the electro-optical didiering system 1, which includes a surface mode device (surface mode liquid crystal cell) switch 11 and double refracting material (birefringent material) 10. At the ouφut of the electro-optical dithering system 11 is a cylindrical lens array 81. The cylindrical lens array includes a plurality of cylindrical lenses located in an appropriate arrangement or pattern, as is known, to direct light to or toward respective eyes 82, 83 of a person, or to some other device able to detect or "see" die light received thereby. By providing a left eye image to the left eye 82 and a right eye image to die right eye 83, an individual viewing die auto-stereoscopic display system 80 will discern a three dimensional or stereoscopic effect. Using me electro-optical didiering system 1 of die invention in combination witii a display source, such as a CRT display 2, a liquid crystal display 20, or some other display, light beam steering can be accomplished to obtain die left eye and right eye images. Therefore, auto-stereoscopic display systems can be provided easily and relatively inexpensively. In Fig. 9 me technique for obtaining beam steering for auto-stereoscopic effect is illustrated. Incident light 4, which is unpolarized, as is represented by the arrows and dots on the light is incident on die plane polarizer 12. Alternatively, plane polarized light can be provided from an image source or light source, such as a liquid crystal display (and polarizer 12 may be eliminated). In any event, die light which exits the polarizer 12 is plane polarized, for example, in a horizontal plane, as is illustrated in Fig. 9. Such light then enters the switch 11 and from mere die light enters and transmits through the double refracting material 10. Depending on whetiier die switch 11 rotates die plane of polarization or it does not rotate the plane of polarization of the light transmitted therethrough, the double refracting material 10 will deflect or will not deflect d e light transmitted therethrough. In d e case uiat the switch 11 does not rotate the plane of polarization, and the above-described alignment of the double refracting material 10 is provided, die light will transmit directly through the material 10 without deflection as light ray 90. When light ray 90 is transmitted dirough the interface 91 between the cylindrical lens 92 of the cylindrical lens array 81 and die external environment, such as air, represented at 93, d e light 90 will refract in die direction of die arrow 94 toward die left eye 82 of the observer (viewer). The light 90 traveling in the direction of the arrow 94 remains polarized in die so-called horizontal direction, i.e., into and out of die plane of die paper of the drawing. However, when the switch 11 rotates the plane of polarization of light transmitted dieredirough, die double refracting material 10 deflects die light, as was described above, resulting in die light 95, which travels to a different location of the interface 91 of the lens 92. The light 95 refracts at die interface 91 and is bent or deflected in die direction of die arrow 96 toward die right eye 83 of die observer. The light 95 is vertically polarized, i.e., die plane of polarization is parallel witii die plane of die paper of the drawing of Fig. 9. In operation of the auto-stereoscopic display 80, left eye and right eye images sequentially are produced by die display 2 (20) for example. When die left eye image is displayed, die switch 11 does not rotate die plane of polarization, and die light 90 follows die direction of die arrow 94 to the left eye 82 of die observer. When the right eye image is produced by the display, die switch 11 does rotate die plane of polarization so tiiat die material 10 deflects die light as light 95 which is refracted to die direction of die arrow 96 to the right eye 83 of die observer. For convenience of this description, it is understood tiiat d e indices of refraction of die material 10 and die material of which die lens 92 is made would be die same or about die same to avoid further refraction at die interface tiierebetween; however, if diere is refraction there, such refraction can be taken into account, as will be appreciated by tiiose having ordinary skill in die art. Referring to Figs. 10 and 11, a display system 99, which includes a liquid crystal display 100, is shown in top plan and top section views. The display system 99 is similar to the several otiier display systems described herein, such as those designated 3, 13, etc. The LCD 100 has a plurality of pixels 101 arranged in respective rows 102 with dead space 103 between respective rows and also at die edge 104 of die display 100. As is seen in Fig. 11, die liquid crystal display 100 includes a substrate 105 on which an active matrix array 106 is located. The liquid crystal display also includes a further substrate 107, a space 108 between substrates where liquid crystal material 109 is located, a seal 110 to close d e space between die substrates, and (not shown) appropriate driving circuitry, as is well known. Light 120 represented by respective arrows illustrated in Fig. 11 is provided by a light source 121 and is selectively transmitted or not through the liquid crystal display. The light 120 is plane polarized by a plane polarizer 122 located between die light source 121 and die liquid crystal display 100, and the light 120 is transmitted or is not transmitted as a function of the plane of polarization thereof relative to an analyzer 123, as is well known. An electrode 124 on die substrate 107 and respective transistors and electrodes of die active matrix array 106 on die substrate 105 apply or do not apply electric field to liquid crystal material 109 at respective pixels 101 to determine whether or not the plane of polarization of light 120 is rotated and, thus, whether such light will be transmitted or will not be transmitted tiirough die analyzer 123. The light 120 which is transmitted tiirough die analyzer 123 is incident on die electro-optical didiering system (EDS) 1. The electro-optical didiering system may be operated to not shift or to shift die location of die light 120 to locations 5a, 5b in die manner described above. If die optical signal at locations 5a, 5b is complementary, as was described above, d e resolution of the optical display system 99 shown in Fig. 11 can be increased. Moreover, as part of such increased resolution, the dead space 103 where transistors 131 and/or ouier components tiiat are not light transmissive in the active matrix array 106 effectively are covered over by the shifted light 5b, for example. Therefore, using the electro-optical didiering system 1 in a display system 99 as described, die light blocking portions of die active matrix array, of conductors, etc., can be in effect overcome or negated while die overall resolution of the display is improved. The parts shown in Figs. 10 and 11 are in a relatively horizontal relation showing didiering in a vertical direction. It will be appreciated tiiat didiering can alternatively be in a horizontal direction or, if desired, multiple electro-optical didiering systems 1 can be used in optical series in order to obtain botii vertical didiering and horizontal didiering. The LCD 100 preferably is relatively fast acting to turn on and off. Therefore, using the combination of die fast acting LCD witii the EDS 1 die respective lines of one subframe of information can be displayed by die respective rows of pixels of the LCD and subsequently die interlaced lines of die next subframe can be displayed by die same respective rows of pixels of d e LCD. The light source for the LCD 100 may be a pulsed source, which produces light ouφut in pulses or sequential bursts. In such case, it is desirable to synchronize die light pulses or bursts of die light source with die LCD and/or witii die EDS 1. Therefore, the respective pixels of die LCD would transmit or block light when the light source is producing a desired light ouφut. The amount of time that die light source is transitioning between a light transmitting or light blocking state may be reduced and preferably is minimized. Also, die LCD would be operative to transmit or to block light when the light source is producing its intended light ouφut ratiier tiian when die light source is not producing a burst of light or a desired light ouφut. This tends to increase die contrast of the ouφut image, since die shutter element (LCD 100) is not changing state when die light is pulsed, e.g. is changing its state from light producing to not producing or vice versa. The EDS 1 and die LCD 100 preferably are synchronized. Therefore, when die LCD is producing scan lines of information from one subframe die EDS is in one state, and when die LCD is producing scan lines of information from die otiier subframe, die EDS is in its otiier state tiiereby causing the lines of one subframe to be interlaced witii the lines of die otiier subframe. The EDS and a pulsating type light source also may be synchronized so tiiat die EDS switches states during die time tiiat no light ouφut or non-optimal light ouφut is produced by die light source. This further enhances contrast of the display system 3, 13, 99. Various circuitry may be used to obtain the aforementioned synchronization. Two examples are shown, respectively, in Figs. 12 and 13. In Fig. 12 an exemplary display system 140 is shown. In die display system 140 a blanking pulse from a source 141 is supplied to respective LCD buffer and EDS buffer circuits 142, 143 to synchronize operation of them. The actual information signals from line 144 indicating the light transmitting or blocking state, for example, of the pixels of die LCD 100, for example, as is shown in Figs. 10 and 11, are provided die LCD buffer 142. Those information signals are not delivered to the LCD 100, though, until appropriately coordinated or synchronized witii die blanking pulses. The EDS 1 is connected to die EDS buffer 143 and receives its drive signal from line 145 to dither or not the optical ouφut from the LCD 100. The EDS buffer also receives die blanking pulse from the source 141 to synchronize delivery of die signals to the EDS with such blanking pulses and or witii die operation of the LCD buffer and information signals delivered to die LCD. The buffers 142, 143 can be synchronized witii respect to each other by appropriate timed operation thereof witii respect to the blanking pulse; or, alternatively, the buffers can be directly coupled to each otiier to synchronize operation ύiereof so that the didiering function is coordinated witii switching of pixels or writing of information to the LCD. As another example of synchronization, Fig. 13 depicts a display system 150 in which a pulsed light source 121, for example, receives pulsed power from a power supply 151. A signal representing die characteristics of die pulsed power from die powers supply 151 is provided to die LCD buffer 142 and EDS buffer 143, which respectively receive information and power signals on lines 144, 145 as described above. By synchronizing die LCD 100 and EDS 1 with respect to each other and/or with respect to the pulsing light source, the LCD can switch states as new information is written thereto when tiie light source is not producing significant light ouφut, and/or die EDS can switch from direct transmission to ditiiered transmission of light states when the light source is not producing a bright ouφut and/or die LCD is not in die process of switching display states. The foregoing are but two examples of synchronization useful in die various display systems and embodiments of the invention. It will be appreciated by those having ordinary skill in die art tiiat many otiier types of synchronizing techniques may be used to obtain die desired synchronization. Although it may be desired to obtain full interlacing and separation of respective lines as in a CRT display, for example, even less tiian full interlacing, e.g., an amount of displacement that does not fully separate die lines but nevertheless reduces the amount of overlap thereof, will tend to reduce d e above-mentioned jitter and improve the optical ouφut of die LCD. Interlacing or didiering can be used to effect vertical displacement (changing of location of die optical ouφut signal), horizontal (lateral) displacement, and/or diagonal displacement of the optical signal, such as that produced as the ouφut from a pixel of a display, e.g., a CRT, LCD, or any otiier type of display. The direction of displacement will depend on die orientation of the various components of the optical system. For example, in die EDS of Fig. 1 having orientation of axes of components shown in Figs 4A, 4B and 4C, vertical displacement will occur. However, by changing die relative orientation of the axes by 45 degrees or 90 degrees, die displacement as a function of die state of die switch 11, for example, can be changed to diagonal or horizontal. Using the vertical displacement of optical signals by die EDS 1 in combination with a display, such as an LCD, for example, it possible in effect to double die resolution of die display in die manner described above. Thus, in a sense, die EDS becomes an optical line doubler which doubles die number of horizontal lines of resolution of the display system. However, by using both vertical and horizontal displacement functions in a display system, it is possible to obtain in effect up to quadruple die resolution of die display relative to operation of die display absent die EDS. Referring to Figs. 14 and 15A-15E an EDS system 201 used with a display 202, in die illustrated embodiment an LCD (although other types of displays can be used), is shown as a display system 203. In Figs. 14 and 15A-15E reference numerals which designate parts that are die same or similar to tiiose described above are die same as die reference numerals that designate such above-described parts except being increased by die value 200. Thus, display system 203 is similar to display systems 3, 13, 99, etc. mentioned herein. However, die EDS system 201 of display system 203 includes two EDS portions 201v and 201h, which respectively can be operated to obtain vertical and horizontal displacement of die optical signal transmitted therethrough. Each EDS 201v, 201h includes, respectively, a double refracting material 210v, 21 Oh and a switch 21 lv, 21 lh. For example, each double refracting material may be a calcite crystal and each switch may be a surface mode (birefringent) liquid crystal cell. The source of optical signals in display system 203 is a flat panel liquid crystal display 202, although other types of displays may be used. The LCD 202 provides light ouφut that is plane polarized, and, tiierefore, a separate polarizer like die polarizer 12 of Fig. 1, for example, may be unnecessary in the illustrated embodiment of display system 203. It will be appreciated tiiat although the display system 203 uses two EDS devices or portions, the principles of die invention may be used witii more than two EDS portions to obtain not only horizontal and vertical displacement but also displacement in even another direction. The relative orientation of the axes of the respective components of the display system 203 is shown in Figs 15A-15E. Plane (linear) polarized light having a horizontal plane of polarization is provided by die LCD 202, as is seen in Fig. 15A. In die vertical displacement EDS 201 v, die axis of die birefringent liquid crystal switch 21 lv shown in Fig. 15B is oriented at 45 degrees to die plane of polarization of light from the source 203; in die illustrated embodiment, such orientation is actually -45 degrees relative to vertical, for example. The projection of die axis of die double refracting material 210v is vertical, as is seen in Fig. 15C. In the horizontal displacement EDS 20 lh, die axis of die birefringent liquid crystal switch 21 lv is oriented at +45 degrees to the vertical (Fig. 15D), and die projection of tiie axis of the double refracting material 210h is horizontal (Fig. 15E). The acmal alignments may be slightly different from those illustrated to accommodate or to compensate for residual birefringence in die liquid crystal switches and/or for other purposes. Also, if desired wave plates and or otiier optical components may be included witii one or more of tiie EDS devices 201h, 201 v to compensate for such residual retardation and/or other factors. The display system 203 can be operated in four different states. In one state shown in Fig. 16A witii botii EDS devices 201v, 201h of Fig. 14 not displacing light, the light from the display source 202 is transmitted widiout being displaced; this may occur with birefringent switches 21 lv, 21 lh being in high voltage, non-polarization rotating state and low, polarization rotating states, respectively. In a second state shown in Fig. 16B witii EDS device 201v, 201h respectively displacing and not displacing light, die light from die display source 202 is transmitted while being horizontally, but not vertically displaced; this may occur with both birefringent switches 21 lv, 21 lh being in high voltage, non-polarization rotating state. In a third state shown in Fig. 16C with both EDS devices 201v, 201h displacing light, the light from the display source 202 is transmitted while being displaced both horizontally and vertically; this may occur with both birefringent switches 21 lv, 21 lh being in low voltage, polarization rotating state. In a fourth state shown in Fig. 16D with EDS device 20 lv, 201h respectively displacing and not displacing light, die light from the display source 202 is transmitted while being vertically, but not horizontally displaced; this may occur witii EDS 21 lv in die low voltage, polarization rotating state and birefringent switch 21 lh being in high voltage, non-polarization rotating state. In Fig. 17 is illustrated a composite of die display conditions depicted in Figs. 16A tiirough 16D. By using relatively fast acting LCD as tiie display source 202 and two EDS devices 201h, 201v synchronized and operated in die manner just described so that the pixels first are shown in the manner in Fig. 16A, then as in Fig. 16B, etc., sufficientiy quickly that die observer's eyes tend to integrate the respective images, a high resolution image with a pixel density like that shown in Fig. 17 can be obtained. It will be appreciated that an exemplary optimum improvement in resolution using die display system 203 in die described manner can increase resolution of die display 202 by approximately a factor of 4. Thus, it will be appreciated tiiat the respective switches 21 lv, 21 lh may be operated according to die following table to obtain die above-described operation controllably to vertically shift or displace and/or to horizontally shift or displace die optical signals from the display 202. High means electrically operated so as to be not polarization rotating and low means electrically operated so as to be polarization rotating, although otiier conventions may be used. TABLE 1 Switch 21 lv Switch 21 lh High Low High Low Low Low Low High In die present invention die switches and double refracting material may be substantially optically transparent. Therefore, those components do not tend to absorb light. The use of such components in a display system 203, for example, does not ordinarily significantly reduce die brightness of the display ouφut. Although two or more images are placed sequentially in die field of view provided by die display system 3, 13, 99, 203, etc., brightness of die display ouφut is not diminished; rather, image resolution can be increased. Otiier types of birefringent materials and/or devices may be used in place of or in addition to die calcite material double refracting device 10 described above. For example, other types of crystal materials and/or minerals may be used; die amount of displacement between an unrefracted optical signal and a refracted optical signal by such double refracting material would depend on index of refraction characteristics of the double refracting material, die index of refraction of the environment external of die double refracting material, wavelength of optical signal, and distance die optical signal travels in the double refracting material. Another double refracting material which may be used in die invention as component 10, for example, is liquid crystal material. Liquid crystal material, such as nematic liquid crystal and smectic liquid crystal material may be birefringent and may be used. Otiier types of birefringent liquid crystal materials also may be used. By organizing or orienting die liquid crystal material in a particular organization or orientation, the transmission of light therethrough witii or without refracting die light can be dependent on die direction of electric vector of die light, e.g., die plane of polarization of plane polarized light. A polymer liquid crystal may be especially useful as such a double refracting material, for such material both can have a relatively large birefringence and also can be formed into a solid material which maintains die orientation of the structure of die liquid crystal material tiiereof . Polymer liquid crystal materials are known. However, if the double refracting material were of a liquid crystal material whose structural orientation or organization could be switched, e.g., in response to application of a prescribed input such as an electric field (or removal of such field or changing voltage or some other characteristic of the field, etc.), then die function of die two components of an EDS may be replaced by a single switchable liquid crystal shutter type device. In this case die liquid crystal shutter could provide one index of refraction or birefringence characteristic to refract light transmitted therethrough a given amount and a different index of refraction characteristic witii no birefringence so as not to refract such light or with parameters to refract die light a different amount. An embodiment of display system 203' which uses a pair of switchable liquid crystal cells 270, 271 associated witii a liquid crystal display 202 * is shown in Figs. 18 and 19. Each of die liquid crystal cells 270, 271 functions as a combination of birefringent or double refracting material 210h, 210v and as a switch 21 lh, 21 lv. The liquid crystal cells may be, for example, aligned like a birefringent liquid crystal cell using nematic or smectic liquid crystal material between a pair of glass plates. The plates are treated so die liquid crystal is aligned generally in die same direction at both plates without twisting; and, therefore is so aligned throughout die cell. The liquid crystal material preferably is tilted, e.g., at 45 degrees, to obtain a desired birefringence characteristic; but although tilted, the projection of the axis of the liquid crystal structure would be in die same plane as die plane of polarization of incident light thereon to obtain die desired birefringence characteristic. The exemplary arrangement of axes of the display system 203' is shown in Fig. 19. By changing die electrical drive signal to the respective liquid crystal cells 270, 271, die index of refraction characteristics thereof can be changed, and, as a result, die location of the optical signal transmitted therethrough can be changed, e.g., ditiiered as described herein. For example, for plane polarized light incident on liquid crystal cell 270 which has liquid crystal therein struc rally aligned such tiiat die light experiences die ordinary index of refraction of die liquid crystal and no birefringence, die light will transmit directly through the liquid crystal cell witiiout refraction. However, if die liquid crystal is structurally aligned such tiiat the light experiences the extraordinary index of refraction and, tiius, birefringence, die light will be refracted at die interface between die liquid crystal material and die glass plate or die like forming or at one surface of die liquid crystal cell 270 at one side; and die light will be refracted again at the interface between die liquid crystal and die glass plate etc. at die other surface of the liquid crystal cell so as to be parallel witii the light incident on die liquid crystal cell 270 but displaced from die extension of the transmission axis of tiie incident light. Thus, by selectively operating, e.g., energizing and deenergizing or changing energization level, die liquid crystal cells 270, 271, then, can change tiie location of the optical signal ouφut by die display system 203'. The liquid crystal should be aligned to present to the light transmitted therethrough either the ordinary or extraordinary axis or index of refraction and appropriate birefringence characteristic as described above. If only one liquid crystal cell 270 is used, die optical signal can be changed back and forth in one plane or direction. If two liquid crystal cells 270, 271 (like the cell 270, for example) are used and are arranged such that die axes thereof are non parallel, tiien the optical signal can be changed back and forth in two planes or directions. Such non-parallel alignment may be perpendicular alignment to obtain up/down didiering and left/right didiering relationships. Since tiie plane of polarization of light incident on die liquid crystal cell 271 should be parallel to the axis of tiiat cell, a half wave plate 272 may be placed between die liquid crystal cells 270, 271 to rotate the plane of polarization of die light exiting the liquid crystal cell 270. For example, die axis of such half wave plate may be oriented at 45 degrees relative to the plane of polarization, i.e., half way between the 90 degrees desired rotation. It is noted that a polarizer 12 is shown in Figs. 18 and 19; such polarizer helps assure die quality of polarization of die light from the display; but such polarizer can be eliminated if die ouφut from the display is of sufficient quality of polarization, e.g., minimal amount of unpolarized light included therein. The EDS 1, 201 may be used in a display system 3, 13, 99, 203, 203', etc. which is monochrome or multicolor. Operation for a monochrome display system would be, for example, as is described above. One embodiment exemplifying operation for a multicolor, such as a red, green and blue (rgb), display system can employ the above-described type of operation for each color. Therefore, when one color or a group of colors is being displayed by respective pixels of such a color display, die optical signal ouφut can be either transmitted without displacement or with displacement in the manner described above. As is depicted schematically in Fig. 20, part of a display 202', e.g., similar to display 202, is shown including three representative adjacent pixel triads 281, 282, 283, each including a red, green and blue pixel portion. The display 202' may be operated in a color frame sequential mode in which respective red, green and blue frames or images are produced in time sequence. In this case all red pixels of respective pixel triads 281, 282, 283, etc. would be red where it is desired in die final image to have red light; subsequently green and then blue pixels of the image would be created. Alternatively, the respective red, green and blue pixels of respective triads can be displaying respective colors simultaneously. In either case, the principles of the invention using die EDS 1, 101, etc. may be used to increase resolution of the ouφut image in die above-described manner. However, die EDS may be used for the purpose of selectively didiering (displacing) less than all of the color frames of a multicolor display, especially if die display is operated in a color frame sequential mode. For example, die didiering function can be used selectively to displace or not die green optical signal (light produced during tiie green frame) of tiie display 3, 13, 99, 203, 200'; however, the EDS may be used so it does not selectively to dirtier die optical signal during one or both of the other color frames. Since the human eye is more sensitive to green light than to red or blue light, a significant enhancement of the apparent resolution of tiie multicolor display can be achieved by only selectively didiering die green light optical signal. If desired, die green and red optical signals can be selectively dithered without selectively didiering die blue optical signal; and this will result in an even greater apparent resolution of tiie multicolor display than if only the green optical signal were selectively dithered. Since the human eye is not as sensitive to blue light as it is to red or green light, the fact that resolution of tiie blue light or blue frame component of the overall image is not enhanced by die didiering of the invention may not significantly reduce die resolution of die composite multicolor ouφut image. By reducing die amount of didiering required, it is possible that the complexity and/or cost of die electronic drive and timing circuitry employed in die invention can be reduced. Referring to Figs 21, and 22A-22F, there is shown a schematic illustration depicting a time sequence of operation of tiie invention using a segmented display system 403. Fig 22A represents die ouφut operation of the display system 403 at one period of time; Fig 22B represents operation at die next period of time; and so on. In Figs. 21 and 22A-22F die various parts which correspond to parts described above are identified by die same reference numerals but increased to a 400 series. Thus, display system 3, 13, 99, 203, 203', etc. in Figs. 21 and 22A-22F is designated 403, for example. The face 470 of me display system 403 in Figs. 21 and 22A-22F is divided into three separate segments 470a, 470b, 470c. More specifically, the display 402 may include a CRT or an LCD 2, 20, 102, etc., and between die display and die viewer, for example, is at least one, and possibly several in series, electro-optical didiering system 1, 11, 21, 101, as was described in tiie several embodiments above. For simplicity of description here die display system 403 is described with only one EDS, though. The EDS 401 includes, for example, a double refracting material 410 and a switch 411 such as a surface mode liquid crystal cell. However, die switch 411 is segmented into several areas which can be separately addressed to change die optical characteristics thereof. The switch 411 is shown in Figs. 21 and 22A-22F as having three separate segments 411a, 411b, 411c; but it will be appreciated tiiat the switch may have fewer or more segments. Each segment 411a, 411b, 411c can be separately operated to change or not to change the direction of plane of polarization of light transmitted therethrough. Each segment can be a separate liquid crystal cell or each can be part of die same liquid crystal cell which has an electrode arrangement which permits operating of die different parts separately. In Figs. 22A, 22B, 22C, respectively, (witii reference also to Fig. 21) the first subframe (field) of information is written sequentially to die upper, middle and lower thirds 402a, 402b, 402c of die display 402 for direct transmission without being ditiiered or shifted in position. By the time the information is being written to the middle tiiird of die display 402, die information written to the top third begins fading; and by die time the information is being written to the bottom tiiird, die information at the top third is substantially fully faded and tiiat at the middle tiiird is beginning to fade. In Fig. 22D die start of information representing die second subframe (field) being written to the display 402, initially to the top third 402a of die display, is shown. The ditiiered information optical signal in the top third of Fig. 22D is represented by die illustrated dashed lines. Since such information is for the second subframe, the optical signal ouφut is intended to be didiered/changed; however, at this time die image or optical ouφut presented by die middle third 402b of the display 402 has not completely faded. Therefore, if die optical ouφut of the entire display 402 were dithered at this time, the optical information or optical ouφut signal still being displayed at die middle tiiird would be shifted to an incorrect location. To avoid this wrongful shifting of die optical signal from the middle tiiird at this time, only the top third 402a of die display 402 is ditiiered. Preferably the top third actually is ditiiered when die previous image there has faded; and tiiat actually can occur at the time period represented in Fig. 22C. At die time period represented by Fig. 22D die middle tiiird of die display 402 has faded, and is ditiiered; and at die time period represented by Fig. 22E, information is written to that ditiiered middle tiiird of die display, and die bottom tiiird which has faded is ditiiered. At die time period represented by Fig. 22F, die ditiiered image information is written to die bottom tiiird of die display 402 and the top third is ditiiered since die information previously written there by now has faded. The above-described operation of the display system 403 can continue sequentially as tiie respective subframes are sequentially displayed, e.g., die optical signals comprising such subframes are presented as die ouφut of die display system. In each subframe the different respective parts or segments are sequentially ditiiered or not preferably so tiiat a segment is already unditiiered or ditiiered before die raster, line, row, etc. of information to form the optical signal is written to the respective pixels of that segment. The didiering or unditiiering switching action, e.g., operation of the respective switches 411a, 411b, 411c from one state to the other, also can be carried out as die action of writing information to a segment is carried out; but ordinarily it would be better to effect d e didiering or unditiiering when the segment is relatively blank (e.g., information there has faded) to avoid undertaking a didiering or unditiiering action while an optical ouφut is being displayed. It will be appreciated tiiat the segmentation technique may be used witii display system which uses a CRT display, a liquid crystal display or some otiier type of display. The segmented switch 411 approach also is useful to remove artifacts caused by a relatively slow acting LCD. Further, it will be appreciated tiiat the various EDS embodiments of die present invention and display systems using such EDS embodiments are operative to move, shift, translate, etc. an ouφut optical signal from one location to another without substantially affecting brightness of the display system or optical signal. The components of the EDS generally are optically transparent, and, therefore, other than a relatively minor amount of absorption of light transmitted therethrough, there may be otherwise relatively little reduction in light intensity. Therefore, the features of the invention may be used for the various purposes described herein, for example, to increase resolution, to cover or to reduce die effective optical dead space, etc., without reducing brightness of the optical ouφut. A passive dithering system 500 in accordance witii one aspect of the present invention is illustrated schematically in Figure 23 in an optical display system 501. The passive didiering system 500 as shown is used in connection with a display 502 which produces an ouφut of polarized light, such as might be produced by a twisted nematic (TN) based flat panel liquid crystal display 504 incorporating a linear polarizer 506 or by a CRT display with an added linear polarizer interposed, as is die polarizer 506, between die CRT display and die didiering system 500. The didiering system 500 includes a pair of double refracting or birefringent material layers 508h, 508v, such as a calcite crystal material, separated by a half wave plate 510. A wave plate 512, such as a quarter wave plate, separates incident plane polarized light into relatively orthogonal plane polarized components for delivery to die birefringent material 508h as an input for die dithering system 500. The effect of the passive dithering system 500 can be to enhance die resolution of die display ouφut by reducing fixed pattern noise in die display. The passive dithering system 500 can increase die number of ouφut pixels provided simultaneously by an optical display system. In Fig. 24a a very generalized example of die function of the passive didiering system 500 is shown considering an image 520a created by a single pixel 520 of die flat panel liquid crystal display 504 separated from adjacent pixels 522 in die display by optical dead space 524. The birefringent material 508h effectively creates a double image 520b of d e image 520a which is displaced or dithered in, for example, a horizontal direction, as is shown in Figure 24b. The second birefringent material 508v, which receives both images 520a and 520b, creates a second pair of images 520b, 520c displaced vertically from the first pair of images as is shown in Figure 24c. In this way, die image produced by a single pixel, such as exemplary pixel 520, can be made to fill or at least to increase the fill of the optical dead space 524 between the pixels 522 which is typically used to electrically isolate adjacent pixels and to accommodate circuitry and electrical components. In other words, die didiering system 500 increases die fill factor of die display 502 as viewed. Therefore, the passive didiering system 500 expands or enlarges the respective pixels. In tiie example of Figs. 24a, 24b, 24c, the pixel 520a can be said to have been expanded or enlarged to cover die area shown in Fig. 24c being occupied by images 520a, b, c, d. If desired, the locations at which the passively ditiiered or created images 520b, c, d are placed may be otiier than or in addition to die optical dead space 524. For example, such image may be placed to overlap another image or pixel, to overlap several images or pixels, image(s) and optical dead space, etc., for example, as is described further below. One possible manner of orienting the axes of the optical components of the passive didiering system 500 in the optical display system 501 is shown in Figure 25a. The linear polarizer 506 or polarized display ouφut is oriented vertically so that an image of a pixel emerging from the polarizer or display will be linearly polarized in a vertical direction, as is shown at pixel 520a in Fig. 25b. In Figs. 25b-g the respective arrows represent direction or plane of polarization of light. The quarter wave plate 512 is aligned witii its axis 512' at 45° to the plane of polarization of the plane (linearly) polarized light incident thereon, e.g., from the polarizer 506. With this arrangement the quarter wave plate 512 converts the incident plane polarized light to circularly polarized light. Circularly polarized light in effect can be resolved into two orthogonal plane polarized components 520a', 520a" which are out of phase by 90°, and such resolution is shown for pixel 520a in Fig. 25c. The birefringent material 508h is arranged relative to the linear polarizer 506 and quarter wave plate 512 with the projection of its optic axis 508h' into the plane of the polarizer 506 and quarter wave plate 512 being horizontal, e.g., parallel to die polarized light component 520a" and perpendicular to die polarized light component 520a. The axis 510' of die half wave plate 510 is oriented at +22.5 degrees to vertical, and die second birefringent material 508v is oriented witii the projection of its optic axis 508v' into the plane of the polarizer 506, etc. being vertical. It will be appreciated, however, that this arrangement is only one of many possible arrangements of die axes of the components which would produce die didiering or pixel expanding or enlarging effect described herein and/or similar or equivalent effects. With further reference to Figures 25a-g, which additionally illustrates the path of an image through die passive didiering system 500, tiie path of the exemplary pixel image 520a through the system will be described in greater detail. As oriented, die linear polarizer 506 transmits optical information in the form of pixel images from pixels in the display which have effected d e light transmitted therethrough so as to be polarized in die direction of tiie transmissive axis 506' of the linear polarizer. For the exemplary image 520a in Fig. 25b, the light would thus be polarized in a vertical direction represented by arrow 520a'. Since die plane of polarization of the image 520a is at a 45 degree angle to die optic axis 512 ' of the quarter wave plate 512, the quarter wave plate converts the plane polarized incident light to circularly polarized light. The circularly polarized light can be resolved or considered as two plane polarized light components 520a', 520a" (Fig. 25c) the planes of polarization of which are orthogonal and die phases of which are 90° out of phase. It will be appreciated that otiier means or techniques may be used to divide the plane polarized light, which is delivered to die birefringent material 508h, into plural components which are acted on differently by the birefringent material, for example acted on in die manner illustrated in Figs. 25a-g or in some other manner. Since the plane of polarization 520a" of some of die light representing pixel 520a in Fig. 25c, which is incident on die birefringent material 508h, is in the place of the optic axis 508h' and encounters birefringence due to die tilting of the optic axis 508h' as was described above, e.g., with respect to Figs. 1-6, such light is refracted by the birefringent material to form the pixel 520b at a location displaced, for example, to die right from pixel 520a, as is seen in Fig. 25d. Also, since die plane of polarization 520a' of some of die light representing pixel 520a in Fig. 25c, which is incident on die birefringent material, 508h, is perpendicular to die optic axis 508h' , the path of such light is not altered by die birefringent material, and pixel 520a is located as is shown in Fig. 25d. Summarizing, as the orthogonally related polarized components pass through the birefringent material 508h, one of die polarized components will be refracted and deflected horizontally while the other component will be unaffected. As a result, the birefringent material 508h will yield two images, an image 520a in its original location and a horizontally displaced image 520b witii the images being polarized orthogonally to one another. The images 520a and 520b then pass through the next optical component in the passive didiering system 500, die half wave plate 510, where die plane of polarization of each of the images 520a and 520b is effectively rotated +45 degrees so tiiat the plane of polarization of each image is as shown in Fig. 25e. The polarizations represented by arrows 520a"' and 520b"' for pixel images 520a, 520b in Fig. 25e are the vector equivalents to the polarizations represented by die respective arrows 520a', 520a", 520b', 520b" for pixels 520a, 520b in Fig. 25f. Two of such vector equivalent polarizations of Fig. 25f are parallel to the optic axis 508v' of die second birefringent material 508v, and two are perpendicular to the optical axis 508v'. Due to such relationships of tiie planes of polarization of each of die images 520a and 520b in Fig. 25f to die axis 508v' of die birefringent material 508v, die images 520a and 520b will be resolved into tiieir orthogonally polarized components 520c, 520d, respectively, as these components pass tiirough the birefringent material 508 v. The polarized components of each image 520a, 520b which are parallel (520a', 520b"') to the plane containing die axis 508 v' will be refracted and deflected vertically to result in images 520c and 520d while die otiier polarized components 520a", 520b', which are perpendicular to die axis 508 v' (or the plane containing that axis) will be unaffected. As a result, die original image 520a is dithered into four images 520a, 520b, 520c and 520d. These images may be of substantially equal intensity. While tiie passive didiering system 500 discussed above was illustrated as doubling images in two directions, horizontal and vertical, a passive didiering system tiiat doubles die image in only a single direction only is also possible. Such a system may include a single birefringent material used in conjunction with a display producing a polarized or non-polarized ouφut to result in a doubled pixel image or to perform passive line doubling. Also, it will be appreciated tiiat the above description with respect to Figs. 23, 24a-c, and 25a-g is exemplary, and other arrangements of components to compose a passive didiering system to obtain a desired pixel enlarging, expanding, shifting, etc. may be employed. For example, a birefringent liquid crystal cell may be used as a wave plate: a surface mode liquid crystal (e.g., U.S. Patent No. Re. 32,521) cell or a pi-cell liquid crystal cell (e.g., U.S. Patent No. 4,582,396) which is tuned to d e desired retardation of quarter wave or half wave are examples. The birefringent material may be liquid crystal cells. Various crystals, prisms, or other devices may be used to provide birefringence and/or polarizing functions. By changing the amount of birefringence and optical path length through a birefringent material the amount of deflection of a pixel image can be determined. Changing relative orientation of axis of one or more components can change the direction a pixel is shifted. Of course, die illustrated alignment of components is relative and reference to vertical, horizontal, into or out of die plane of die paper or drawing only is for convenience of description. All such equivalent and alternate or additional materials and/or alignments of components and functional operation are considered within the scope of the present invention. As is evident from die description above with respect to Figs. 23-25 and die description below witii respect to Figs. 26-32, in an exemplary passive didiering system of die invention, birefringent material may be used to change location of light representing a pixel, an image of a pixel, or another optical signal (for convenience sometimes simply referred to as pixel). The passive didiering system, therefore, is able to change the apparent location of the pixel. Such change may result in an increase in or enlarging of die pixel size, in a doubling or duplicating of die pixel, etc; such change in location may simply be a change in tiie apparent location of the pixel without any doubling, duplicating, changing of size, etc. When die passive didiering system is used to dither a pixel to change size, e.g. , effectively to enlarge die pixel, the didiering system may cause there to be multiple spaced apart pixels derived from die original pixel or pixels. Alteratively, one or more of the multiple pixels may overlap or be sufficientiy adjacent to another pixel as to be considered touching or in any event not spaced apart. As an example, by enlarging a pixel to cover optical dead space of a display, die apparent resolution of die display usually is increased even witiiout increasing the actual number of pixels driven by die display. In die case of a pixel being expanded using an exemplary passive didiering system according to die invention, light from die original pixel is distributed over a viewed area tiiat is larger than the area of the original pixel of die display. However, die total amount of light reaching the eye of an observer, for example, remains substantially the same as that provided by die original pixel before being expanded because the components of the passive didiering system are not the light absorbing or blocking type. Therefore, die apparent brightness of a display when used in combination with such a passive didiering system would tend not to be diminished. The passive didiering system of the invention is described witii respect to several embodiments. These embodiments are examples of components and arrangements of components to obtain die passive didiering effect of die invention. Many otiier components and arrangements of components also may be used to obtain passive dithering, as will be appreciated by those who have ordinary skill in die art. For example, in die embodiments of passive didiering systems illustrated in Figs. 23-27 a half wave plate is used to set up particular plane polarization conditions, such as direction of plane of polarization; and in die embodiments illustrated in Figs. 28-32 a quarter wave plate is used to set up particular plane polarization conditions. In die embodiments of passive didiering systems illustrated in Figs. 23-25 and 28-30 die passive didiering systems receive plane polarized light input from a liquid crystal display tiiat provides plane polarized light ouφut or from another display which may not provide a plane polarized light ouφut but which is used in combination with a plane polarizer to obtain the desired polarized light input to die didiering system. However, in the embodiments illustrated in Figs. 26, 27, 31 and 32 die passive didiering systems receive and operate on unpolarized light. The components of die respective passive didiering systems described witii respect to Figs. 23-32 are arranged to expand a single pixel or light forming that pixel to four pixels which are arranged in a two by two rectilinear array, such as that depicted by pixels 524a-d in Fig. 24c. However, it will be appreciated by tiiose who have ordinary skill in die art tiiat the passive didiering systems of tiie invention may be adjusted, including changing of optical axes orientations, changing of birefringence value, adding or deleting components, etc., to expand die single pixel to fewer or to more than four pixels and to arrange tiiose pixels in a rectilinear array or in another pattern or arrangement. Also, although quarter wave plates and half wave plates are disclosed useful in passive didiering systems, it will be appreciated that other types of wave plates or appropriate means may be used, too. Preferably die wave plates and/or otiier appropriate means provide die same or substantially the same wave plate function, such as optical retardation, for all, for a relatively wide range of wavelengths of light or at least for the wavelength range intended to be used. Using die principles of die invention to expand a pixel formed of plane polarized light, die incident plane polarized light is divided into two orthogonally related plane polarized components. A quarter wave plate may be used for this function. A quarter wave plate having its optic axis aligned at 45° to die plane of polarization of incident plane polarized light converts the plane polarized light to circular polarized light, which can be resolved to orthogonally related plane polarized components which are of equal amplitude but are out of phase by 90°. If the quarter wave plate is oriented at other than 45° to the plane of tiie incident plane polarized light, die ouφut therefrom will be elliptically polarized, which also may be resolved to respective plane polarized components possibly witii phases that differ by other than 90° and/or amplitudes which are not equivalent. Means otiier than a quarter wave plate also may be used to effect such separating of die incident plane polarized light into respective distinguishable components. The incident plane polarized light, which is resolved to respective distinguishable components, is directed to d e birefringent material, which separates the components in effect by directing diem to different locations and thereby expands die apparent area of die pixel. For unpolarized light input to a passive didiering system of die invention used, for example, to expand a pixel, die incident light is directed to birefringent material usually without the need to plane polarize the incident light. Since die incident light already includes or can be considered as being resolved to two orthogonally related plane polarized components, the birefringent material separates the respective orthogonally plane polarized components in effect by directing diem to different locations and thereby expands the apparent area of die pixel. Referring to Fig. 26, there is shown a passive didiering system 500' of an optical display system 501' used in connection with a display 532 which produces non¬ polarized (unpolarized) light, such as a nematic curvilinear aligned phase liquid crystal (NCAP), polymer dispersed liquid crystal (PDLC) or liquid crystal polymer composite (LCPC) based flat panel liquid crystal display. The passive didiering system 500' of Fig. 26 includes d e same optical components as die didiering system 500 described above relative to Fig. 23-25, such as a birefringent material 508h, a wave plate 510 and a second birefringent material 508 v. In this instance, neither the passive didiering system 500' nor die display 532 is provided witii a linear polarizer to polarize the ouφut light from the display. In operation, the passive didiering system 500' when used in connection with a display producing non-polarized light will result in horizontal and vertical pixel image doubling similar to that produced by die passive didiering system 500 and shown in Figs. 23-25. In fact, die orientations of the optic axes 508h\ 510' and 508v' of die components 508h, 510, 508v, shown in Figs. 26 and 27 may be die same as when tiiose components are used in connection with a display producing a polarized ouφut. (If it were desired to use die didiering system 500 with an unpolarized light producing display 532, die polarizer 506 could be placed optically between tiie display 532 and die didiering system 500 in die manner shown in Figs. 23-25, for example). One possible set of orientations for tiie optic axes of these components is shown in Fig. 27. The optic axis 508h' of the first birefringent material 508h is vertical and is tipped as was described above, die axis 510' of die half wave plate 510 is at +22.5° to vertical and die projection of the optic axis 508v' of the second birefringent material 508v into the plane of die page is horizontal and is tipped as was described above. Although the light which enters tiie first birefringent material 508h is non-polarized, it can be visualized as polarized light resolved into two orthogonal components such as a vertical and horizontal polarized component as shown by arrows in the exemplary pixel image 534a created by a corresponding pixel 534 in die display 532. The components 508h, 510 and 508v then function basically as described above in Fig. 25. The first birefringent material 508h will resolve the individual components of the pixel image 534a into their orthogonal components and will dither (shift location of) one polarized component relative to the other polarized component to produce a horizontally displaced double image of die pixel image 534a. The half wave plate 510 will en rotate the polarization components of tiiose images as in Fig. 25e so they are at 45 ° angles to the optic axis 508v' of the second birefringent material 508v where tiie images will be doubled and displaced in a vertical direction as in Fig. 25g. As a result, die initial image 534a is doubled in die horizontal direction and then the initial image and die doubled image are doubled in the vertical direction to produce four adjacent images which may substantially cover the portion of the original pixel 534a in the display and dead space surrounding die pixel in one vertical and horizontal direction. Fig. 28 illustrates an alternate embodiment of a passive didiering system 540 of an optical display system 541 shown witii an optical display which produces linearly polarized ouφut light, such as by a twisted nematic based flat panel liquid crystal display 542 incorporating a linear polarizer 544. The passive didiering system 540 includes a first birefringent material 546 v, a second birefringent material 546h and quarter wave plates 548, 549, respectively, interposed between the source of polarized light (display 542 and, if used, polarizer 544) and the first birefringent material 546v and between die birefringent materials 546h and 546 v. One possible set of orientations for the axes of the linear polarizer 544 of the display, die birefringent materials 546v and 546h and die quarter wave plates 548, 549 is shown in Fig. 29. The linear polarizer 544 has a transmissive axis in die vertical direction. The projection of the optic axis of the first birefringent material 546h into tiie plane of die transmission axis of tiie linear polarizer also is vertical, i.e., parallel to the axis of the polarizer. The axes of the quarter wave plates 548, 549 are oriented +45°to vertical and die projection of tiie optic axis of the second birefringent material 546h into the plane of the linear polarizer is at +90° to vertical, i.e., horizontal. The passive didiering system 540 functions basically the same way as the passive didiering system 500 is described above relative to Fig. 25. The function of tiie half wave plate 510 in tiie passive didiering system 500 has been replaced in the system 540 by a quarter wave plate 549. The quarter wave plate 548 and birefringent material 546v function as the quarter wave plate 512 and birefringent material 508h of Figs. 23-25. The quarter wave plate 549 effectively divides die polarized light components of light passing tiirough die wave plate 549 by converting the light to circularly polarized light and its respective equivalent orthogonal plane polarized components like the quarter wave plates 512, 548 do. The components of the circularly polarized light are then ditiiered by d e second birefringent material 546h in a horizontal direction as explained above for die passive didiering system 500. One advantage of using the quarter wave plate 549 as opposed to die half wave plate 510 or 510' is tiiat t e quarter wave plate 549 will tend to introduce less chromatic aberration on the light passing therethrough since a quarter wave plate usually is thinner material than a half wave plate and, therefore, usually is less dispersive, e.g., exhibits less optical dispersion. In Figs. 30a-30e are shown die operation of the passive didiering system 540 of Figs. 28 and 29. In Fig. 30a a pixel 542a of display 542 is shown. Light from pixel 542a is vertically polarized and is represented by die vertical arrow therein. The linear polarization is produced by d e display 542 and/or is due to the polarizer 544. A separate polarizer 544 ordinarily is unnecessary if the display 542 produces polarized light ouφut. Optical dead space 550 surrounds die pixel 542a. The quarter wave plate 548 divides die vertically polarized light from die polarizer 544 to obtain two orthogonal plane polarized components, as is seen in Fig. 30b. In Fig. 30c it can be seen tiiat the birefringent material 546 v changes tiie location of the vertically polarized light component portion of light incident thereon moving that light vertically relative to the location of tiie vertically polarized light component portion. Therefore, pixel 542a is expanded, e.g., is doubled, in tiiat pixel area 542b now has been created. The quarter wave plate 549 divides die plane polarized light from the birefringent material 546v so that each pixel 542a, 542b has both orthogonal plane polarized light components, e.g., horizontal and vertical, as is shown in Fig. 30d. In die manner described above, die double refracting material 546h expands, e.g., doubles, die pixels 542a, 542b to create pixel areas 542a, 542b, 542c, 542d shown in Fig. 30f. Figs. 31 and 32 illustrate a passive didiering system 540' which is identical to die passive didiering system 540 shown in Figs. 28-30 but it is used in an optical display system 541' witii a display producing non-polarized (unpolarized) ouφut light, such as an NCAP, PDLC or LCPC based flat panel liquid crystal display 560 e.g., like die display 532 and pixels 534 of Figs. 26 and 27. The orientation of the birefringent materials 546v and 546h and die quarter wave plate 549, which are represented in Fig. 32, may be die same as tiiose described for the like components for tiie passive didiering system 540 although it would be appreciated tiiat this is only one possible set of orientations for the axes of the components which would dither an image in die manner described above. The passive didiering system 540' functions in basically tiie same way described above for the system 540 but on unpolarized input light, which is resolved as orthogonally related plane polarized light components (see die description above concerning Figs. 26 and 27), as opposed to the linearly polarized light which die system 540 receives from the display 542. It also will be appreciated tiiat the several features and embodiments of die invention illustrated and/or described herein may be used witii other features and embodiments tiiat are illustrated and/or described herein as well as equivalents thereof. For example, in die segmented display system described the EDS may be formed by a calcite crystal and a surface mode liquid crystal cell, by a calcite crystal and a twisted nematic liquid crystal cell or by some other type of switch and/or some other type of double refracting material. Also, the EDS may be a liquid crystal EDS in which both the switch function and die double refracting function can be carried out by tiie same device, e.g., as in die embodiment of Figs. 18 and 19. Moreover, in many instances passive didiering systems may be used in conjunction with or as a substitute for some of all of the components described for the EDS. These are simply examples of combining features and it will be appreciated tiiat other combinations also may be made consistent witii the spirit and scope of die invention. From the foregoing it will be appreciated tiiat various embodiments of die invention using principles described herein may be employed witii polarized light or unpolarized light. If it possible to operate based on an unpolarized light as an input to the dithering system, e.g., using an NCAP display, there is no need for a polarizer and die undesirable effect that a polarizer has in blocking approximately 50% of the transmitted light. It also will be appreciated that in various embodiments described herein a quarter wave plate may be used, a half wave plate may be used, and/or a combination thereof may be used. In various embodiments a half wave plate may be substituted for one or more quarter wave plates and vice versa. A quarter wave plate may be used to convert plane polarized light to circular polarized light or to orthogonal components of plane polarized light. A quarter wave plate also may be used to convert plane polarized light to elliptically polarized light. A half wave plate is used to rotate die plane of polarization of plane polarized light. Usually die half wave plate will rotate the plane of polarization by twice the angle between the plane of incident plane polarized light and die axis of die half wave plate. Turning to Fig. 33 an active didiering system 601 is used witii a display 602 in an optical display system 603. The didiering system includes a birefringent material 610, such as a calcite crystal, having an axis 610' tiiat is oriented at an angle tiieta relative to horizontal, as is depicted in Fig. 33. The didiering system 601 also includes a switch 611 , such as a birefringent liquid crystal cell of die type described above. The display 602 may be a liquid crystal display tiiat provides plane polarized light ouφut tiiat has a vertical plane of polarization represented by the arrow 602 * . Alternatively, the display 602 may provide otiier than plane polarized light ouφut, and in tiiat case a plane polarizer 612 may be used to provide such vertical polarization of the light delivered from the display and polarizer to die switch 611. The orientation of die axis of d e birefringent liquid crystal switch 611 is at 45° to die vertical plane of polarization 602' , as is represented by die arrow 611'. As was described, as die switch 611 is energized or not, the plane of polarization of the light ouφut therefrom will be the same as the direction of the arrow 602', i.e., vertical, or horizontal. A half wave plate 615 between the switch 611 and die birefringent material 610 has its axis 615' oriented at an angle relative to horizontal that is 1/2 theta. With reference to Figs. 33 and 34, which presents representative operation of die didiering system 601 , when die light transmitted through the switch 611 has a given plane of polarization, such light will be transmitted tiirough the half wave plate 615 and birefringent plate (calcite) 610 to appear at the same relative positions as they originally appear in the display 602. If such pixels are, respectively, red, green and blue pixels of a triad, such pixels may be at d e locations of the pixel images 620r, 620g, 620b shown in Fig. 34. However, when the plane of polarization of tiie light exiting the switch 611 is such that it is appropriately rotated by die half wave plate 615 so as to impinge on die calcite 610 in a direction relative to the axis 610' to cause shifting of the light ouφut, such pixels will appear as images 620r', 620g', 620b'. Thus, it will be seen that the offset or shifting is in a sense diagonal rather than horizontal or vertical. The angle at which such diagonal occurs relative to horizontal, for example, depends on the magnitude of die angle tiieta. Thus, it will be appreciated by appropriately selecting die angles of die respective axis of the components and their relationship to each otiier, whereas desired directions of shifting can be obtained. Also, die extent or distance of such shifting can be determined, for example, by the thickness of the birefringent device 610, i.e., die effect of optical thickness thereof having an affect on the light transmitted therethrough. Refeπing to Figs. 35 and 36 and die Chart I below, an optical display system 640, which includes two active didiering systems 641, 642 and one passive didiering system 643 is illustrated. The optical system 640 receives plane polarized light input 644 from a display 645. If die display 645 is not tiie type that provides a plane polarized light ouφut, than an additional polarizer 646 may be used to provide such plane polarization. The orientation of respective components of the display system 640 is depicted by respective double-headed arrows above the various components. The display system 640 may be used to provide a video ouφut display operation. In an exemplary video display system, such as an NTSC or PAL system, it is conventional to compose a picture or a frame from two interlaced and sequentially presented fields (sometimes referred to as sub-frames). The optical display is able to produce four ouφut conditions and signals in die manner described below. Such four ouφut conditions may correlate to two respective frames and the two respective fields in each frame in a video display system, such as a television system using a liquid crystal display or some otiier display as die image source. However, it will be appreciated tiiat the four ouφut conditions described below may be correlated witii the operation of otiier types of display systems or witii a video display system in a way different from die exemplary operation described below. In the optical system 640 the active didiering system 641 includes a switch 650 and a birefringent device 651. The active didiering system 642 includes a switch 652 and a birefringent device 653. The passive didiering system 643 includes a quarter wave plate 654 and a tiiird birefringent device or material 655. The first and second switches 650, 652 may be respective surface mode birefringent liquid crystal cells or some other switch as is described elsewhere herein. The first, second and tiiird birefringent devices 651, 653, 65 may be calcite material or some other birefringent material having axis oriented generally in the manner illustrated and tipped in die manner described above. In describing operation of the optical display system 640, reference is made to a pixel of die display and light representing tiiat pixel. The passive didiering system 643 effectively doubles the size of the pixel received by it from the display 645 and via die respective active dithering systems 641, 642. Therefore, as is seen in Fig. 36, each pixel input to die passive didiering system 643 is shown in solid lines and die doubled image thereof is shown in dotted lines adjacent thereto. For example, the pixel provided die passive didiering system 643 for the first field of die first frame is represented at 660, and die ditiiered image 660' is shown adjacent thereto in dotted lines. The passive didiering system operates in the manner of the passive didiering systems described above, for example. Referring to die Chart I below, at frame 1, field 1, die voltage or energization of the first switch 650 is low so that the switch rotates the plane of polarization of the input vertically polarized light to horizontally polarized light as die ouφut therefrom; see the column labeled "polarization direction ouφut 1" having die letter "H" representing such horizontal polarization. Delivery of that horizontally polarized light to die first calcite 651 results in no shift of location. Continuing in tiie first line for frame 1, field 1 in die Chart I below, the voltage of the second switch 652 is low, whereby tiiat switch rotates the plane of polarization back to vertical, as is represented by die letter "V" in die column labeled polarization direction ouφut 2; and, tiierefore, the second calcite member 653 does not shift the location of the pixel. When tiie vertically polarized light ouφut from tiie second calcite 653 enters die quarter wave plate 654, such light is divided into horizontal and vertical polarized components; the vertically polarized component transmits through the third calcite material 655, and d e horizontally polarized component is shifted horizontally thereby effectively doubling die size of the pixel and producing die image 660', as is represented in the last column of tiie table designated calcite 3 shifting and doubling in die horizontal direction the particular pixel. The second field of die first frame, for example, each pixel of die second frame, is displaced vertically relative to the corresponding pixel of die first field of die first frame. The pixel 661 represents the location of such downwardly vertically displaced pixel for the second field of die first frame when the display system is a video type using interlaced fields to produce a frame. The second line of the Chart I below shows the conditions of die surface mode switches 650, 652, both being at high voltage so as not to rotate tiie plane of polarization of light transmitted therethrough, the resulting vertical downward displacement caused by die first calcite 651 , and die doubling of the pixel by the passive didiering system 643 to produce not only pixel 661 but also die ditiiered pixel 661'. In pixels 660, 660', die two digits one in each represent, respectively, first frame, first field; and in die pixels 661, 661', die digits one and two represent first frame, second field, respectively. Lines three and four of the Chart I below represent conditions and shifting resulting from tiiose conditions of die switches 650, 652, direction of plane of polarization, etc. as was described above with respect to the first two lines of the Chart I below in order to achieve pixels 662, 662' and 663, 663', die primed pixels representing the ditiiered images that doubles tiie effective size of the overall pixel, such as the doubled size 663 plus 663'. As was mentioned above, the amount of shifting or translating of a particular pixel may be a function of die birefringence and/or optical thickness of the respective birefringent device, such as die respective calcite plates 651, 653, 655. Also, in a conventional video system mere usually is no horizontal interlacing. The two field of die second frame represented by pixels 662, 662', 663, 663' may represent images moved to fill optical dead space, images to effect super imposing respective colors, as is described further below, or some other purpose. The increasingly effective size of each pixel, such as by doubling it to increase pixel 660 to the effective size of the sum of pixels 660, 660', can be used to improve resolution by effectively covering optical dead space in die display. The vertical displacing of pixels can be used to cause a liquid crystal display to provide a true or more nearly true interlaced operation whereby a pixel presented in one field of a frame is presented at a different location when the second field of tiiat same frame is produced. An advantage to de use of a didiering system with a display, such as a liquid crystal display, wherein the location of a pixel in the ouφut can be shifted even though the actual location of the pixel in tiie display itself, such as an LCD, remains fixed is tiiat correct data can be used to drive die pixel to provide die desired image ouφut witii relatively accurate following of the video signal. In a conventional LCD used to provide a video ouφut a particular pixel may average the two fields of a frame; the average is not «i" accurate representation of the data received from die video signal. However, using a didiering system in accordance witii the present invention, a pixel of the LCD may be driven based on information from die video signal intended to drive tiiat pixel for a particular field of a frame to provide a visual ouφut from the display system, such as display system 640. Subsequently when tiie image ouφut of the respective pixel is shifted so tiiat it is in the location desired for die second field of die particular frame, the actual information from the video signal that ordinarily would be used, say in a CRT, for example, could be die information that is used to operate or to drive die pixel which then provides a relatively accurate ouφut representative of the appropriate input signal. Using the two active and one passive dithering systems of the optical display system 640 is it possible to obtain eight copies of die original image, if desired, namely that provided at pixel 660, for example. Such eight copies may be obtained for every field for every frame, if desired and, tiius, provide a macro pixel effectively about eight times the size of the pixel 660. In another embodiment, the data picked off die incoming analog signal or other video signal that operates the pixel 660, e.g., to turn it on or off, may be selected at die appropriate time to drive the pixel 660; and subsequently tiie pixel 661 may be operated as a function of information picked off die incoming video or analog signal representing the desired operation of the pixel 661 for interlaced fields operation of a conventional NTS or PAL system. However, additionally, if desired, die information from the incoming signal also could be picked off to represent die on/off or intensity effect of a pixel presented at location of pixel 662 accurately to represent that pixel even though that pixel physically may not be in the display 645 but rather is represented by tiie pixel of the display 645 that produces pixel image 660 shifted to die location of pixel 662. In other words, in an exemplary LCD there may be two relatively adjacent pixels, and die information from the incoming video signal would be picked off from tiiat video signal to drive die respective pixels at the appropriate times. However, there also may be information contained in the video signal tiiat would represent a desired optical ouφut from die optical display system 640 from a pixel located between die two mentioned pixels. The present invention allows the information from the video signal that would be used to drive such intermediate pixel to be delivered to die pixel of die display 645 tiiat would produce pixel image 660 while die didiering systems in die optical display system 640 effect horizontal or lateral displacement of die optical ouφut to a location where such intermediate pixel might otherwise appear in the ouφut image from d e Optical display system 640. This operation can enhance the resolution provided by die optical display system 640 and die accuracy of representation of the information carried by die input video signal, etc. Superimposed Color Operation Referring to Fig. 37 there is a shown a layout of an exemplary group of red, green and blue pixels of an exemplary liquid crystal display. The pixels are arranged in respective parallel rows and columns. Capital letters represent the color of the pixel, e.g., whedier the pixel will deliver ouφut like tiiat is red, green or blue. Portions of two rows are shown. In the viewing of a color liquid crystal display die eye of die viewer, i.e., a human eye, may receive light input from many different pixels, and die eye effectively integrates die light inputs. One way of considering such viewing is to analogize the adjacent pixels, which are extremely small, effectively being superimposed so that the light therefrom is superimposed. Therefore, die combination of red, green and blue light tiiat is superimposed would provide a white light as seen by die viewer. The various embodiments of didiering systems in accordance with the present invention, including tiiose disclosed and equivalents thereof, may be used to effect real superimposing of respective pixels, thereby enhancing the color ouφut or color response of a color liquid crystal display. Such superimposition is depicted in Fig. 37 and now is described. The two rows of pixels shown in Fig. 37 are portions of respective rows of pixels in a color liquid crystal display. In die first row shown there are five pixels of the indicated colors; and in the second row there also are five pixels of the indicated colors. The sequence of colors is red, green and blue in both rows, but the sequence is offset by one pixel one row to the otiier. Therefore, in the first (top) row tiie first pixel row, and in the second row die first pixel is green. The arrangement of pixels in Fig. 37 is exemplary. Many otiier types of arrangements of pixels may be used whether in parallel rows and columns in die manner shown, in a so called delta configuration or pattern wherein there is an offset of rows, such as in Fig. 40, etc. Using the optical display system 640, for example, the red pixel Ra at die top left of Fig. 37 is duplicated by the passive didiering system 643 to produce a red pixel or Ra, which is represented in dash lines. Operation of die first didiering system 641 produces a second copy of botii those red pixels displaced downward to locations of dash red pixels designated ra'. Such operation of tiie first didiering system 641 is coordinated witii the second didiering system 642 to effect such downward shift. Similarly, horizontal shifting of all four red pixels just mentioned, namely Ra, ra, and die two designated ra' to a horizontally shifted or laterally shifted place results in die red pixels represented by dash lines and designated ra", one of which is superimposed over d e green pixel Ga and one of which is superimposed on die blue pixel Ba. Such shifting may occur in a time sequence that is sufficiently fast that the human eye does not perceive the various shifts. Additionally, such shifting occurs in a time sequence coordinated with the desired color ouφut from the display as represented by die input video signals to die display so that tiie superimposed colors provide a good quality and accurate representation of the color ouφut from the display intended as a result of die input video signal. Similarly to the just described shifting of die red pixel Ra, shifting of the green pixel Ga also occurs, and such shifted pixels are represented by dotted outline at pixel locations represented by Ga due to die passive didiering system 643, and die otiier shifted pixels represented by dotted lines labeled ga' and ga" resulting from coordinated operation of die active didiering systems 641, 642. Furthermore, similar operation occurs for the blue pixel Ba, which is represented by phantom lines at pixels or pixel locations designed ba, ba', and ba". The four blue pixels represented by respective designations ba' and ba" near the bottom of Fig. 37 would overly or be superimposed on otiier pixels which are not shown in order to simplify die drawing and description. Briefly referring to Fig. 38, shifting of the red pixel R into respective gaps and also superimposed on otiier pixels is shown schematically and simply. Specifically, pixel R is doubled by die passive didiering system 643 of the optical display system 640 in Fig. 35, for example to provide pixel r. Both pixels R and r are duplicated also at pixel image locations r' shown in Fig. 38 in the gap between respective parallel rows of actual pixels. Pixels R, r and r' also are duplicated to die right relative to the illustration of Fig. 38 as pixel images r", some of which are in die same gap as pixel images r' and one of which overlies or is superimposed on die green pixel G. Thus, it will be seen tiiat the pixels can be shifted to various locations in die display to achieve die desired optical ouφut. As the display of Fig. 38 is operated as part of the optical display system 640 to duplicate pixel images and/or to translate pixel images, so, too, tiie display shown in Fig. 39 represents similar modified operation of the optical display system 640. In particular, in Fig. 39 lateral shifting occurs like that in Fig. 38; but in Fig. 39 the vertical shifting of images results in the shifted image overlying the gap between adjacent rows of pixels of die display 645 and also overlying at least a portion of the pixel of the display 645 which is vertically displaced beyond such gap between pixel rows. Placing die pixel image in a gap increases the fill factor of the display. As was mentioned above, die shifting may result in superimposing pixel images to achieve the superimposed color response described above. Also, if desired, die vertical shifting may result in a portion of die shifted pixel image still overlapping a portion of die image in die original row, such as die illustrated pixel R and shifted pixel image r' therebelow. Such superimposing of pixels may provide a desired type of visual ouφut for die optical display system 340. Briefly referring to Figs. 40 and 41, there is shown a delta design of pixel layout for a display in Fig. 40, such as an LCD 645 and die ouφut images therefrom after transmitting tiirough an optical display system 680, which includes one active didiering system 681 and two passive didiering systems 682, 683. The active didiering system 681 includes a switch, 684, such as a birefringent liquid crystal cell, and a calcite crystal 685 able to transmit an image or to shift the image vertically 1/2 pixel, depending on die direction of plane of polarization of light incident thereon. The passive didiering system 682 includes a half wave plate 686, which rotates the plane of polarization of incident light 45 degrees, and a second calcite crystal 687, which can transmit the incident pixel image and has a thickness, birefringence, axial orientation and tipped to displace die image 1/2 triad pitch horizontally. The passive didiering system 683 includes a half wave plate 688, which rotates die plane of polarization of incident light 45 degrees, and a second calcite crystal 689, which can transmit the incident pixel image and has a thickness, birefringence and axial orientation and tip to be able to displace the image 1 pixel pitch horizontally. The optical display system 680 and didiering systems 681, 682, 683 thereof are set up to effect shifting 1/2 triad pitch to die right; 1 pixel pitch left and 1/2 pixel vertical pitch down. This arrangement is represented by only die blue pixel Ba. In shifting tiiat pixel 1/2 triad pitch to die right, pixel ba results. In shifting both pixel Ba and ba 1 pixel pitch to die left, two respective pixel images ba' are produced~one is superimposed over the green pixel G, and one is in the gap between the blue pixel Ba and the red pixel R horizontally adjacent to the blue pixel Ba. Such shifting provides botii for filling tiie optically dead space and effecting a superimposing of respective color pixel images as was described above. The shifting of pixel images vertically to form the four pixel images ba" places some of those in the gaps between rows of pixels and some in superimposed relation to die same and/or otiier pixels or shifted pixel images. Referring to Fig. 42, a person 704 is shown wearing a head mounted viewing system 705 in accordance witii the present invention. The viewing system may be part of a virtual reality viewing system having one or more displays which are viewed by die person. The viewing system may be part of a telecommunications system, entertainment system, or some other device in which light, optical, etc. information can be presented for viewing, projecting, photographing, or other use. Exemplary systems in which the invention may be used are disclosed in die above-mentioned patent applications; of course there may be other uses, too. The head mounted viewing system 705 includes a housing 705h in which die various components of die viewing system 705 are included, and a mounting device 705m, such as a strap, eyeglass or goggles type frame support structure, etc. The mounting device 705m mounts die housing 705h for support from die head of die individual 704 placing die viewing system 705 in position in front of one of the eyes for viewing of an image presented by the viewing system 705. Whether the viewing system 705 is hand held, head mounted, or otherwise supported, for example, from a pedestal, tripod, frame, etc., from a table, from die floor, from a console 9, etc., preferably die viewing system 705 and housing 705h thereof is relatively small and sufficientiy lightweight to facilitate moving, transporting, mounting, and/or holding. If the viewing system 705 is to be hand held or head mounted, it especially should be relatively lightweight to avoid being a weight burden on die hand or head of die individual using die viewing system 705. Also, to facilitate holding die viewing system 705 manually or head mounting tiie viewing system, the viewing system 705 should be relatively small. An exemplary viewing system may be, for example, approximately - 63 - 4 to 5 inches in height, approximately 2 to 3 inches wide, and approximately 1 1/2 to 2 inches deep. These are exemplary only, and it will be appreciated tiiat other dimensions may be used. In using the viewing system 705 it may be head mounted, hand held, coupled to a control box, console or the like, for example, similar to the main body of the conventional telephone when used in a telecommunication system. Turning to Fig. 43, the viewing system 705 is shown in detail as a monocular viewing system. The housing 705h includes a viewing portion 711 and a support portion 712. The viewing portion 711 is intended to be viewed by an eye 713 of a person 704 (Fig. 42), and the support portion 712 is intended to be held in die hand of tiiat individual. As was mentioned above, a head mount 705m may be provided to support the viewing system 705 from the head of a person. Thus, the housing 705h may be hand held, supported by a strap, cap, temple piece as in eyeglasses, or otherwise mounted for viewing by a person. The viewing system 705 includes an optical system 714 in the housing 705h. The optical system 714 includes an image source 715, such as an LCD, that provides images for viewing by the eye 713 through a viewing port 716. A viewing lens 717 (or group of lens) presents to the eye 713 an image which appears at a comfortable viewing distance, such as about 20 inches or more away. An image resolution enhancing device 18 (sometimes referred to as an optical line doubler or OLD, didiering device or system, EDS, etc.) optionally included in die optical system 714 may be used to enhance d e resolution or otiier qualities of the image produced by die image source 715. A number of optical components 720 are included in die optical system 714. The optical components include focusing optics 721 (sometimes referred to simply as "lens" or as projection optics or as a projector), a beam splitter 722, and one or more retroreflectors 23, 23'. The image source 715 includes a display 724d and a source of incident light 724i. The light source Uluminates die display 724d, and die display in turn presents images which can be projected for viewing by the eye 713, as will be described in greater detail below. It will be appreciated tiiat other types of image sources may be used, examples being cathode ray tube displays, otiier liquid crystal displays, plasma displays, etc. Examples of several displays and light sources are presented in d e above-referenced co-pending patent applications. A connection cable 28 provides electrical and/or optical signals and/or power to die optical system 714, and is particular to die image source 715 and OLD 18 to develop die above-mentioned images for viewing by die eye 713. A control system 29 is coupled to die cable to provide such electrical signals for controlling operation of die display system 705, as is described in further detail below. Summarizing such controlled operation, though, the display 724d may be a twisted nematic liquid crystal display, and die OLD 18 includes an optical switch, such as a surface mode liquid crystal cell, tiiat switches polarization characteristics of light to cause the light ouφut to viewed by die eye 713 to be, for example, of enhanced resolution, as is described further below. Therefore, the control system 29 provides signals to generate the image by the display 724d; and die control system 29 also controls the optical switch to effect a synchronization such that there is a phase or time delay between die signals to die twisted nematic LCD and die signals to die optical switch. Accordingly, die optical switch which operates at a different speed, e.g., faster or in shorter time than die twisted nematic LCD will be coordinated witii the operation of the twisted nematic LCD to improve operation and optical ouφut of the display system 705. Detailed operation of the control system is described further below, for example, with respect to Figs. 44-46 and 48. Dithering may refer to the physical displacement of an image. The didiering system 18 may be an electro-optical didiering system (EDS), which refers to an electro- optical means to physically shift or to change the location of an optical signal, such as an image. The shifting may result in doubling of die number of pixels or scan lines of a display-thus, reference to OLD (optical line doubler). The shifting also may result in quadrupling (or more or less increase) pixels or scan lines; and in such case OLD also may be used as a generic label. The shifting may be active in response to an electrical, magnetic or other input. The didiering system 18 may be passive, e.g. , in which shifting occurs constantly or substantially constantly (or continuously); in other words such shifting may occur all the time without die need for a separate input to cause shifting. Various embodiments of didiering systems useful in die invention are described above. The image may be shifted along an axis from one location to another and then back to the first, e.g. up and tiien down, left and tiien right, or both, etc. The optical signal may be moved in another direction. The didiering may be repetitive or periodic or it may be asynchronous in moving an image from one location to another and tiien holding it there, at least for a set or non-predetermined time. Also, as was mentioned, die didiering may be passive, and, thus, constant, e.g., without changing. When the didiering is passive there usually are provided simultaneously die original image at the undithered location and a second or ditiiered image at another location, e.g., located adjacent or spaced apart from die undithered image. Referring to Fig. 44, the top line A in the graph represents an electrical signal, namely the voltage applied to a given display pixel (sometimes referred to as picture element or component) as a function of time. The pixel may be a part of a twisted nematic type LCD, such as part of the display 724d, especially an active matrix LCD, although the pixel may be a part of some otiier type of display, optical device, etc. When die voltage is applied to an active matrix display, it results in an electric field being applied across die liquid crystal material causing a particular type of operation, e.g., alignment with respect to the field or when no field is applied relaxing to an alignment which may be influenced, for example, by the surfaces, surface coatings, etc., of die liquid crystal cell or device forming LCD. The voltage A illustrated in Fig. 44 is applied at a frequency of 60 Hz. The second line B in Fig. 44 represents the desired light transmission characteristic of an ideal pixel as a function of time. In the illustrated example, die pixel is switched between clear (sometimes referred to as die white state) and dark (sometimes referred to as die black state). As illustrated, die clear state would occur when tiie voltage A is high, and the dark state would occur when the voltage A is high. In die illustrated case of an ideal pixel in Fig. 44, die pixel switches transmission B from dark to clear at die same time the voltage switches from high to low. That is, the ideal pixel switches in phase with the applied voltage A. Furthermore, in the OLD or EDS 1, etc. (Figs. 1, 2-6, 11-12, etc.) hereof (hereinafter referred to as EDS 1 for brevity although such reference includes die various embodiments of active and passive didiering systems disclosed herein), die position of the pixel changes by switching the voltage applied to die surface mode birefringent liquid crystal cell, optical switch or polarization rotator 11 (Figs. 1, 5 and 6, for example). Therefore, it follows that in the ideal case, i.e., for use with the ideal pixel, die voltage applied to die optical switch 11 also would be switched synchronously witii the voltage A applied to die ideal pixel and in phase. However, a real liquid crystal display 20, 724d utilizing tiie twisted nematic effect cannot switch between transmission states as rapidly as indicated in die second line B of Fig. 44. For example, the active matrix liquid crystal display used in die Sony XC-M07 monitor can switch from dark to clear in about 20 milliseconds and from clear to dark in about 11 milliseconds. Switching time is defined conventionally as die time required for the transmission to change between 10% and 90% of die final values. This real switching behavior is illustrated in die tiiird line C of Fig. 44. In this third line C depicting light transmission, the transmission of the clear state has been normalized to 100% and die transmission of the dark state has been normalized to 0%. It will be appreciated that the graph line C is schematic only, and die precise times mentioned above are not necessarily accurate. In Fig. 45 die graphs present information similar to that presented in die graphs of Fig. 44 except that in the graphs of Fig. 45 the frequency of the applied voltage A' to die pixel, e.g., of die display 724d, is doubled to 120 Hz. The transmission B' of the ideal pixel in Fig. 45 is shown synchronized and in phase witii the applied voltage A'. However, the actual transmission C of a real pixel is illustrated in die third line of Fig. 45. As is shown, within the available time of respective half cycles of the applied voltage A', die real pixel is able to switch transmission between about 25% and 75 % . This means tiiat the contrast ratio would be reduced by a factor of about one half (1/2) compared to the 60 Hz case of Fig. 44. This behavior is characteristic of many twisted nematic effect LCDs; starting at a modulation of about 60 Hz. every increase in the frequency of the applied voltage by a factor of two (2) usually results in a reduction in die contrast ratio by a factor of about one half (1/2). Referring to Fig. 46, line A" represents the applied voltage to die pixel at 120 Hz. The second line C" represents die transmission response of a real pixel of an active matrix twisted nematic LCD. Note that line C" is similar to line C in Fig. 45. A guide line D has been drawn in die graph of line C" in Fig. 46 at 50% transmission. That portion of a particular frame, in which tiie real pixel is presenting an image of clear or dark, having a transmission greater than 50% is defined here as the clear state. That portion of the frame having a transmission less than 50% is defined here as the dark state. As seen, die real pixel does shutter light at 120 Hz but the transmission modulates between 25% and 75% ratiier than the 0% to 100% experienced when die frequency of the applied voltage signal A was 60 Hz. in Fig. 44. Another feature of die 120 Hz response of the real pixel is shown in Fig. 46. Consider the point marked along die time scale by the double headed arrow E. The bottom part of the arrow E indicates die point in time that the transmission of the real pixel switches from dark to clear; the top of the arrow E indicates die corresponding applied voltage. It can be seen that the applied voltage A" is out of phase with the transmission characteristics of the pixel, i.e., when the real pixel switches between what is considered die clear state and die black state, by 90°. In die present invention the EDS 1 may be adjusted to introduce a similar phase shift in the voltage F (Fig. 46) applied to die optical switch 11. An exemplary optical switch 11 is a surface mode birefringent liquid crystal cell. Such device usually can switch between states in response to a change in input signal much faster than does a twisted nematic liquid crystal cell or LCD. Therefore, by introducing die indicated phase shift in die driving of the surface mode liquid crystal cell and die twisted nematic LCD, the optical switch can be coordinated to switch optically at die same time that the LCD 724d, for example, switches optically from what is considered its clear state to what is considered its dark state or vice versa. As a result, as the EDS 1 operates in coordination with the LCD 724d, for example, to crispness or sharpness of the ouφut image can be improved and there is less likelihood of a bleeding effect between images produced by pixels which are periodically optically shifted using die didiering principles of an OLD or die like. After die phase of die surface mode liquid crystal cell optical switch 11 has been adjusted as described, the contrast of the display 724d would be reduced by a factor of about one half (1/2) when die display is optically doubled and one fourth (1/4) when the display is optically quadrupled. The decrease in contrast is due to die increased frequency at which die display liquid crystal cell (LCD) is driven, not due to die EDS or how it is driven. It has been found that die contrast reduction is nearly undetectable by die human eye and, therefore, has been found acceptable for many applications. It will be appreciated tiiat although the above description regarding Figs. 44-46 presents phase shift of 90° for die indicated purpose, die principles of the invention may be used to introduce otiier phase shifts to achieve a similar coordination between two optical devices which have different response characteristics, such as, for example, change in light transmission or polarization as a function of change in electrical input, or other input, e.g., magnetic input. In Fig. 47 details of optical components of the optical system 714 of the display system 705 are shown. The optical components shown in Fig. 47 are similar to those included in die housing 705h of Fig. 43; however, in Fig. 47 die housing 705h and support 705m are not shown to facilitate illustrating the invention and to simplify the drawing. The optical components 720 of the optical system 714 include focusing optics 721 (sometimes referred to simply as "lens" or as projection optics or as a projector), a beamsplitter 722 and retro-reflector 723. The display system 705 also may include an image source 715 (Fig. 43) which provides images or light having characteristics of an image and, if desired, may be part of die mentioned projector. An exemplary image source is a liquid crystal display, such as a small liquid crystal television having a cross-sectional display area on the order of about one square inch or less. As shown, the image source 715 includes a liquid crystal display 724d which modulates light from the light source 724i to form images for viewing by the eye 713. Alternatively, the image source may be separate and simply used to provide one or more images or light having image characteristics that can be provided by die viewing system 705, such as tiiat shown in Fig. 1, or a head mounted display, sometimes referred to as HMD to die eye 713. Additional optical components of tiie optical system 714 may include linear polarizers, circular polarizers, wave plates, focusing elements, such as lenses or mirrors, prisms, filters, shutters, apertures, diaphragms, and/or otiier components that may be used to provide a particular type of ouφut image for viewing by tiie eye 713. Examples of several embodiments using such additional optical components are described below with respect to other drawing figures. The invention is useful witii virtually any type of image source or display source. An example of such a display source is a compact flat panel display, and especially one utilizing a reflective liquid crystal display made from a single crystal silicon active matrix array. In Fig. 47 die image source 715 displays an image 825, which is shown in die drawing as an arrow 826. The light 827 leaving the image source 724 represents an image or has characteristics of an image, and tiiat light is collected by die focusing optics 721 of tiie optical system 714 of the display system 705 and travels to the beamsplitter 722. In Fig. 47 and in a number of the other drawing figures hereof die focusing optics 721 is represented as a single lens. However, it will be appreciated tiiat the focusing optics 721 may include one or more other components, such as lenses, reflectors, filters, polarizers, wave plates, etc. Although tiie image source(s) 715 is shown in Fig. 47 located relatively above the beamsplitter 722, the image source may alternatively be located below die beamsplitter as is shown in Fig. 2. At least some of die light 827a incident on die beamsplitter 722 is reflected by die beamsplitter as light 827b toward die retro-reflector 723. The retro-reflector may be, for example, a screen made of retro-reflecting material. Exemplary retro-reflectors are well known. One example is that known as a corner reflector or a sheet having a plurality of corner reflectors. Another example is a material having plural glass beads or other refracting and/or reflecting devices on or in a support. An example of a retro- reflector is a film or sheet material having a plurality of corner cubes which material is sold by Reflexite Corporation of New Britain, Connecticut. Such material is available having about forty-seven thousand corner reflectors per square inch. The light (light rays) 827c, which are shown as broken lines, are reflected by die retro-reflector 723 such tiiat their path is exactly back along their direction of incidence on die retro-reflector. In this way the light rays 827c pass through the beamsplitter 722 and are focused directed toward a location in space designated 828 in the illustration of Fig. 47. The eye 713 of a viewer (person) can be placed approximately at location 828 to see the image, and die pupil and lens, individually and collectively designated 713a, of die eye, accordingly, are shown at tiiat point. The lens 713a focuses die light incident thereon as an image on the retina of the eye 713. The projection lens 720 projects light toward the retro-reflector 723 to cause a real image to be formed at die retro-reflector or in front or behind die retro-reflector. As is defined in Jenkins & White, Fundamentals Of Optics, McGraw-Hill, 1976, for example, using an exemplary projection lens, an image is real if it can be visible on a screen. The rays of light are actually brought to a focus in the plane of the image. A real image is formed when an object is placed beyond die focal plane of a lens; die real image is formed at die opposite side of die lens. If die object is moved closer to die focal plane of die lens, die image moves farther and is enlarged. In contrast, a virtual image occurs if an object is between die focal point of a lens and die lens itself. In Fig. 47 die broken lines represent light rays which travel after reflection by tiie retro-reflector along the same or substantially the same path, but in the opposite direction to, respective incident light rays impinging on the retro-reflector. Thus, the retro-reflector 723 is part of a conjugate optics path 823a in which light incident thereon is reflected in die same path and opposite direction as reflected light. The beamsplitter 722 directs light from the focusing optics 721 into that conjugate optics path and toward die retro-reflector; and die beamsplitter also passes light in the conjugate optics path from the retro-reflector to the ouφut port 16 (Fig. 2) for viewing by die eye 713. The beamsplitter 722 and retro-reflector 723 cooperate as a conjugate optics system to provide tiiat conjugate optics path. Using the described conjugate optics path and system, relatively minimal amount of the light from the image source 724 and focusing optics 721 is lost and, conversely, relatively maximum amount of light is directed to die eye 713. Also, there is substantial accuracy of image and image resolution conveyed to die eye. Furthermore, especially if a relatively good quality retro-reflector is used so that the precise location at which die image 830 is in focus will not be critical, e.g., it can be behind or in front of the retro-reflector, the tolerance required for die relative positioning of die components of die optical system 714 is less severe. This makes the HMD display system 705 relatively robust and reliable. In Fig. 47 the viewed image 830 is represented by an enlarged arrow 831. Such arrow 831 is shown in Fig. 47 as a magnified focused image of die image 825 from die image source 724. The image 830 may be in focus at or approximately at the retro- reflector 723, and this is especially desirable for good quality images to be provided die eye 713 when a relatively low quality retro-reflector is used. A low quality retro¬ reflector is one which has relatively low resolution or accuracy of reflecting light in a conjugate manner in the same path but opposite direction relative to the incident light. Witii a low or poor quality retro-reflector and die image not being focused at die retro¬ reflector, it is possible that too much light may be lost from the desired conjugate optics path back to the eye 713, and this can reduce die quality of die image seen. However, the image 830 may be in focus at another location or plane either behind die retro-reflector (relative to the eye) or in front of the retro-reflector, and this is easier to do while maintaining a good quality image for viewing when the retro-reflector is a good quality one. The better the retro-reflector, die more self-conjugating is the optical system 714 and die less die need to focus witii precision at the retro-reflector. Retro-reflector quality may be indicated by die radians of beam spread of light reflected. For example, a relatively good quality retro-reflector may have from zero or about zero radians of beam spread to a few milliradians of beam spread. The quality usually is considered as decreasing in proportion to increasing beam spread of reflected light. In considering die brightness of die image seen by die viewer, the nature of the beamsplitter 722 plays a role. The light produced by die image source 724 may be polarized or unpolarized. If the beamsplitter 722 is of a non-polarizing type, tiien a balanced situation is to have 50% of tiie light incident on die beamsplitter 722 be reflected and 50% transmitted. Thus, of die light 827a incident on die beamsplitter 722, 50% is reflected and sent toward the retro-reflector screen 723 as light 827b. Of the reflected light 827c from the retro-reflector 723, 50% of the light will be transmitted tiirough the beamsplitter 722 and will travel to the viewer's eye 713. This configuration of the optical components 720 of the display system 705 can transfer to the viewer's eye a maximum of 25% of die light produced by die image source 724. If desired, the beamsplitter 722 can be modified in ways that are well known to change the ratio of the reflected light to transmitted light thereby. Also, die beamsplitter 722 may include an anti-reflection coating so that all or an increased amount of the image comes from one side of die beamsplitter and thus to reduce the likelihood of a double image. Since the optical system 714 of die display system 705 provides good resolution of the image and maintains die characteristics thereof, die image source can be a relatively inexpensive one that does not have to compensate for substantial loss of image quality tiiat may occur in prior display systems. Furthermore, since a relatively large amount of die light provided by die image source 724 is provided to die eye 713 for viewing, e.g., since die retro-reflector can virtually focus the light for viewing at the eye, additional brightness compensation for loss of light, as may be needed in prior display systems, especially portable, e.g. , hand held or head mounted, ordinarily would not be required. For exemplary purposes, in Fig. 47 three light rays 840a, 840b, 840c (collectively 840) originating at tiie tip of the arrow 826 constitute a portion of the light 827. Three light rays schematically shown at 841a, 841b, 841c (collectively 841) also are examples of light emanating at die tail of die arrow 826. The light 827 has characteristics of the image 825 from or provided by or at die image source 715, and represented by die exemplary light rays 840 and 841, is focused by die focusing optics 721 onto tiie retro-reflector 723. The size of the image 830 seen as die arrow 831 on the retro-reflector 723 depends on die focal length of the focusing optics 721 and die distances between die image source 724 and die retro-reflector 723 from the focal points 843, 844 of the focusing optics 721. Thus, magnification can depend on such focal length. The image source 715 should be located relative to the focusing optics 721 such that an image can be focused, e.g., in focus as is shown in Fig. 47, at or approximately at the retro-reflector. For example, the image source 715 may be beyond die focal point 843 of the focusing optics 721, and die retro-reflector likewise preferably is beyond the focal point 844 of the focusing optics so that the image can be focused at die retro-reflector. In die illustration of Fig. 47 the image 830 on tiie retro-reflector 723 is magnified relative to the size of the image at the image source display 724d; it does not have to be magnified. The image 830 may be die same size as die image 825 or it may be smaller. Thus, although die image source display 724d may be relatively small and/or may provide a relatively small size image 825 at its ouφut, the size of the image 830 viewed by die eye 713 may be different. The optical system 714 is operable to place the image plane effectively at the retina of die viewer's eye 713. This is accomplished by effectively putting the plane of the eye lens (or pupil) 713a effectively at die position occupied by die focusing optics 721 relative to the source of the image provided to die focusing optics. In a sense the lens 721 is optically superimposed on die lens 713a of die eye 713. The invention provides an optical system in which there are conjugate paths from a lens, such as focusing optics 714, which corresponds to die "lens means" of an optical sensor, e.g. , the eye 713. Stated in anotiier way, the invention presents visual information or optical data witii a wide field of view by taking die ouφut from a lens (focusing optics 721) and reflecting the light back along a conjugate path toward a location corresponding to tiiat of the same lens which was in the original path, but actually direct tiiat reflected light onto die eye placed at such corresponding location. This is obtained by using die conjugate optics arrangement disclosed herein. The human eye is most comfortable when viewing an image at a distance of about twenty inches, approximately at the distance at which one would place a book, document, etc. to be read. It is desirable tiiat the final image as seen by die viewer be located at such distance, e.g., approximately twenty inches from the pupil 713a of the eye. This can be accomplished in die manner, if desired, by adding an additional lens 717 (Fig. 43) or other optical system (not shown) between the beamsplitter 722 and die eye 713. Such lens may cause die person to see a virtual image behind die retro¬ reflector, as is described in several of the above patent applications. Although in many viewing devices further spacing between the eye and die optical component of the optical system nearest die eye may be desired to obtain desired eye relief, the use of the lens 717 at the indicated distance of about 1/2 to 1 inch from die eye usually is acceptable and reasonably comfortable because that is die approximate spacing of ordinary eye glasses to which people ordinarily relatively easily become accustomed. The function of the lens 717 may be obtained by using a negative lens at the focusing optics 721. Referring to Fig. 14 an EDS 201 in die form of an electro-optical didiering system which includes two line doubters in optical series is shown used witii a display 202, in the illustrated embodiment an LCD (although other types of displays can be used), as a display system 203. The display 202 and die EDS 201 may be substituted for the display 724d and EDS 1 in the display system 705 of Figs. 42 and 43. The display 202 may include a light source or a separate light source 724i may be used to illuminate the display 202. Fig. 48 presents a number of graphs representing signals in the control system 729 for tiie display system 705 or display system 203 to present an image that is enhanced by optical didiering (optical line doubling, in fact quadrupling) and tiiat is enhanced by die phase shifting of the invention as described herein. The respective signals are shown on a time scale presented on die "x" axis. Vertical sync pulses G from a conventional video signal used for driving a television, CRT, LCD, etc., are presented at periodic intervals, e.g., at a frequency of 60 Hz. (one pulse each about 16.67 milliseconds (ms)). An odd/even frame signal H also is presented; this signal is approximately a square wave having high and low half cycle portions, each half cycle occurring over a period of about 16.67 ms. The high portion of the frame signal represents an odd or even frame, and low represents the other frame. A video data delay signal I controls delivery of video data; high is on and low is off. In die display system 203 there are two surface mode liquid crystal cells 21 lv, 21 lh, hereinafter sometimes abbreviated SMD (for surface mode device), which serve as respective polarization rotators or optical switches. It will be evident tiiat other types of switches may be used. As is known, one type of operation of an SMD results in the SMD having two states, one in which it provides substantially no optical phase retardation of light, for example, zero or near zero, and one in which it provides a relative maximum amount of optical phase retardation, for example, 90 degrees, 45 degrees, etc. , depending on die optical thickness of tiie SMD and/or on otiier properties of the particular SMD. Usually the minimum and maximum optical phase retardations are produced, respectively, when a respective relative maximum and minimum voltage is applied across die liquid crystal cell forming die SMD. Usually, the minimum voltage is a non-zero rms voltage which preconditions die liquid SMD crystal cell, sometimes referred to as biasing die SMD, to help maintain die alignment of the liquid crystal material in die maximum optical retardation condition. In one example, the preconditioning is provided by a constantly applied voltage in die "low voltage" or maximum optical retardation state. In another example, the precondition is provided by die effect of an rms voltage occurring as a result of periodically driving die liquid crystal cell witii a voltage that varies between an instantaneous value of a maximum level and zero. In this case, the voltage is reapplied before die liquid crystal cell can relax fully. Other techniques for driving an SMD also may be possible. As is seen in curve J, die voltage waveform applied to the SMD 21 lv (Fig. 14) varies at the extremes J' between -15 volts and +15 volts which provides minimal optical phase retardation (rotation of die plane of polarization). Portions J" of the voltage J also are at plus and minus a small voltage that is slightly above and below, respectively, the zero voltage level; these portions J" are the voltage of the SMD when it is in the maximum optical phase retardation condition (providing maximum rotation of plane of polarization). Each portion J' and J" of die voltage J is the same duration as the respective half cycle of the odd/even signal H and the same duration as the time period between vertical sync pulses G. However, the phase of the voltage waveform J is shifted from die phase of the vertical sync G and odd/even frame signal H by an amount which is determined in die manner described above wkh respect to Figs. 44-46, for example. That phase shift in the illustrated example is 13.2 milliseconds, as is evident from die scale at die bottom of Fig. 48. Waveform signal or voltage K in Fig. 48 is applied to die SMD 21 lh (Fig. 14). It varies only at one half (1/2) the frequency of the waveform J. As an example of operation of die display system 203, which is not necessarily coordinated witii the sequence of Figs. 16A-16D, although producing die result of Fig. 17, incident plane polarized light is provided to and transmitted tiirough the SMD's 21 lh and 21 lv, which are operated generally according to die waveforms J and K. Therefore, the polarization of light respectively entering the birefringent crystals, e.g., calcite or other birefringent material, 210h, 210v will vary generally in the manner depicted by curves L and M, which is synchronized and in phase or approximately in phase with the operation of the SMD's 21 lh, 21 lv. As light transmits tiirough die respective birefringent crystals 210h, 210v, the location of the image from respective pixels of the display 202 will vary generally along the lines of tiie curves N and O. The description herein refers to direction, e.g., horizontal and vertical; it will be appreciated tiiat such reference only is exemplary, and where vertical shifting or orientation is referred to, horizontal could be substituted, and vice versa. The phase shifting for coordination of optical switching with an optical display, for example, as described above, also may be used in a display system that provides multicolor ouφut with good contrast even though brightness or intensity of die ouφut light is varied, for example, of die type disclosed in above-referenced patent application Serial No. 08/187,163. Using such phase shifting in coordination witii the liquid crystal display system of such patent application and/or witii the didiering of others of the patent applications referenced above to provide a multicolor ouφut can increase the resolution, sharpness and crispness of the viewed image, for example. Referring to Fig. 49, a light transmissive display system according to an embodiment of die invention is illustrated at 901. The display system 901 includes a light source 902, liquid crystal display 903, such as tiiat shown at 724d in Fig. 43, optics 904, such as that shown at 14 in Fig. 43, for projection or viewing of tiie images created by die liquid crystal display, a computer control 905, such as tiie control 729 in Fig. 43, and an image signal source 906, which may be part of the control 905 or a separate source of video signals or other signals as may be appropriate. A photodetector 907 also may be included in die system 901. The light source 902 may be one or more light emitting diodes, incandescent light source, fluorescent light source, light received via fiber optics or other means, a metal halide lamp, etc. The liquid crystal display 903 may be a twisted nematic liquid crystal cell, a variable birefringence liquid crystal cell, a supertwist liquid crystal cell, or some other type or liquid crystal cell able to modulate light. The liquid crystal display 903 may include polarizers, wave plates, such as quarter wave plates or otiier wave plates, means for compensating for residual birefringence or for problems encountered during off axis viewing, etc. Other types of display devices which modulate light as a function of some type of controlled input can be used in place of die liquid crystal cell 903. Exemplary liquid crystal cells and display devices which may be used for die liquid crystal cell 903 are disclosed in U.S. patents Nos. 4,385,806, 4,436,376, 4,540,243, Re. 32,521, and 4,582,396, which disclose surface mode and pi-cell liquid crystal devices, and in concurrently filed, commonly owned U.S. patent application Serial No. 08/187,050, entitled "Folded Variable Birefringence Liquid Crystal Apparatus. " The optics 904 may be one or more lenses separate from and/or included as part of the liquid crystal display for die purpose of providing an ouφut image for viewing or for projection. If for viewing, such optics 904 may be one or more lenses which focus an image for close, e.g., as in a head mounted display of die heads up display type, virtual reality type or multimedia type, or far viewing, e.g., as in a slide viewer or a television. If for projection, such optics 904 may include projection optics which project an image formed by die display 903 onto a screen for transmissive viewing or reflective viewing. The image signal source 906 may be a source of computer graphics signals, NTSC type television (video) signals, or other signals intended to produce an image on die display 903. Such signals are decoded in conventional manner by the computer control 905, for example, as is the case in many display systems, and in response to such decoding or deciphering, the computer control 905 (or some other appropriate control, circuit, etc.) operates the display 903 to produce desired images. If desired, die computer control 905 can operate the display 903 in sequential manner to produce multiple images in sequence while the display is being illuminated by only a single light source or color of light, e.g., a monochromatic type of operation. Exemplary operation of this type is summarized in die above '396 patent. Otiier exemplary types of operation of the computer control 905 include tiiose employed in conventional liquid crystal display televisions of die hand-held or larger type and/or liquid crystal type computer monitors. Alternatively, the computer control can operate the display 903 in a field sequential or frame sequential manner whereby a particular image is formed in several parts; while one part is formed, die display is illuminated by light of one color; while another part is formed, die display is illuminated by light of a different color; and so on. Using this field sequential type operation, multicolor images can be produced by die display system apparatus 901. In a typical input signal to a television or liquid crystal television, there is information indicating brightness of die light to be transmitted (or reflected) at a particular pixel. The computer control 905 is operative to compute the brightness information of a particular image or scene and in response to such computation to control the intensity or brightness of the light source 902. While intensity or brightness of die light source is controlled in this manner, tiie computer control 905 operates die liquid crystal display 903 to modulate light without having to reduce die number of pixels used to transmit light. Therefore, die full number or a relatively large number of pixels can be used to form die image or scene even if the brightness of die scene as controlled by die controlled light source is relatively dark. Information coming through from the image signal source 906 may indicate various levels of illumination. There usually is a blanking pulse and a data line pulse. The computer control 905 can take the integral of the data line electrically or an integral of die whole set of data (from all of die data lines of die scene) or all of the pixels while electrically skipping the blanking. Based on tiiat integral, the brighmess of the light incident on die display 903 is controlled by die computer control 905. It will be appreciated that a person having ordinary skill in the art would be able to prepare an appropriate computer program to provide die integral functions and to use the results of such integration to provide brightness control for the light source 902. From the foregoing, then, it will be appreciated tiiat the apparatus 901, including tiie computer control 905, is operative to control or to adjust die brighmess of a scene without degrading die contrast ratio. Thus, the same contrast ratio can be maintained while brightness of a scene or image is adjusted. For example, die same contrast ratio or substantially the same contrast ratio can be maintained by the apparatus 901 , whether depicting a scene of a bright sunlit environment or of die inside of a dark cave. Therefore, die scene will have die appearance of illumination under natural illumination conditions. The features of die invention described below can be used in virtually any passive display system. Power requirements of the apparatus 901 can be reduced over prior display systems because die intensity of light produced by die source 902 is controlled to create dark images. In prior systems, though, the intensity of tiie light produced by die source was maintained substantially constant while die amount of light permitted to be transmitted tiirough the passive display would be reduced to create a dark scene image. In addition to controlling intensity of die light source 902 as a function of brightness of a scene, the computer control 905 also may be responsive to measurement or detection of die ambient environment in which die apparatus 901 is located. The brighmess of such ambient environment may be detected by die photodetector 907. The photodetector 907 may be place in a room or elsewhere where the image created by die display 903 is to be viewed; and die brightness of the source 902 can be adjusted appropriately. For example, if die room is dark, it usually is desirable to reduce brightness of die source; and if die room is bright or the apparatus is being used in sunlight, die brightness of the source may be increased. Turning to Fig. 50, a light reflective display system according to die invention is illustrated at 901'. The display system 901' includes a light source 902', liquid crystal display 903', optics 904' for projection or viewing of the images created by die liquid crystal display 903', a computer control 905', and an image signal source 906. A photodetector 907 also may be included in die system 901. The various parts of die display 903 * and optics 904' may be the same or similar to those disclosed in the U.S. patent applications referred to above. The light source 902' and display 903' may be of the type disclosed in concurrentiy filed, commonly owned U.S. patent application Serial No. 08/187,262, entitled "Illumination System For A Display. " For example, die light source 902' may include a source of circularly polarized light 902a' and a cholesteric liquid crystal reflector 908. The liquid crystal display 903' may be a reflective variable birefringence liquid crystal display device. Full Color Frame Sequential Illumination System and Display. Turning to Fig. 51 a full color display subsystem 919 including illumination system 920 is shown. However, in die display subsystem 919 die illumination system 920 includes several sources of light, each having a different wavelength. For example, three separate light sources 902r, 902g, 902b provide red, green and blue wavelength light, respectively, or light that is in respective wavelength bands or ranges that include red, green and blue, respectively. The light sources may be respective light emitting diodes or they may be other sources of red, green and blue light or other respective wavelengths of light, as may be desired for use in die display subsystem 919. The cholesteric liquid crystal reflector 908 is able to reflect green light; the reflector 908a is able to reflect red light; die reflector 908b is able to reflect blue light. Such reflection occurs when the circular polarization characteristic of the light is the same direction as die twist direction of die cholesteric liquid crystal material in die respective reflector. The reflectors 908, 908a, 908b are transparent to the other polarizations of incident light and to die otiier wavelengths of incident light. The illumination system 920 is intended sequentially to illuminate the display 903', which may include a wave plate, such as a quarter wave plate, (or respective portions of the display) with respective wavelengths of light. For example, for a period of time the display 903' (or portion thereof) is illuminated with red light; subsequently illumination is by either green or blue light; and still subsequently illumination is by the other of green or blue light. Such sequential tilumination may be carried out sufficientiy rapidly so tiiat respective red, green and blue images created by die display 903' when illuminated by die respective colors of light are ouφut from the display subsystem 961 and are integrated by die human eye. As a result, the human eye effectively sees a multicolor image. Other examples of frame sequential switching to provide multicolor and/or full color ouφuts are known in the art. Various advantages inure to a frame sequential multicolor display, including die ability to provide high resolution witii approximately one-third die number of picture elements required for a full color r, g, b display system in which respective pixels are red, green or blue. The sequential delivering of red, green and blue light to die display 903' is coordinated by the control system 905 with die driving of die display 903'. Therefore, when a red image or a portion of a red image is to be produced by die display 903', it is done when red light is incident on die display 903'; and die similar type of operation occurs witii respect to green and blue images. If die respective light sources 902r, 902g, 902b are light emitting diodes, they may be sequentially operated or energized to provide light in coordination witii the operation of the display 903' under direct control and or energization by the control system 905. Alternatively, the control system 905 may be coordinated witii whatever other means are used to provide die respective red, green and blue color lights of die light source. Another example of frame sequential or field sequential operation of a displays subsystem like tiiat shown at 961 herein is described in die above-referenced patent applications. Another example of field sequential operation is described in U.S. patent No. 4,582,396, which is mentioned above and incorporated by reference. Referring to Fig. 52, a head mounted display 960 includes a pair of display systems 961, 962 and a control system 705 for creating images intended to be viewed by die eyes 964, 965 of a person. The display systems 961, 962 may be positioned in relatively close proximity, for example, at approximately one inch distance, to die respective eyes 964, 965. A mounting mechanism, such as temple pieces 966, 967 and a nose bridge 968 may be provided to mount die display 960 on die head of die person. The control system 905 in conjunction with the display systems 961, 962 are intended to create images for viewing by the eyes. Those images may be monochromatic. The images may be multicolor. The images may be two-dimensional or they may provide a three dimensional, stereoscopic effect. Stereoscopic effect viewing is obtained when die control system 905 operates the display systems 961 , 962 to provide, respectively, right eye and left eye images tiiat are sufficientiy distinct to provide depth perception. Right eye, left eye imaging and depth perception are techniques used in some stereoscopic imaging and viewing systems which are commercially available. The display systems 961, 962 may be identical. The control system 905 provides control and/or power input to the display systems 961, 962 to create images for display to die eyes 964, 965. The display 960 may be a head mounted display, such as a heads-up display, a virtual reality display, or a multimedia display. The control system 905 may be generally a control system of the type used in known head mounted displays to create such images. Such a control system may provide for control of color, light intensity, image generating, gamma, etc. The display systems 961, 962 may include focusing optics so as to focus die image created by die display systems for comfortable viewing, for example from a few inches up to a few feet in front of the eyes, say, from about 20 inches to about several feet in front of the eyes. It will be appreciated tiiat the features of the liquid crystal cell 903' may be used in die display 960 of the head mounted type. Also, features of die invention may also be employed in otiier types of display systems. One example is a display system that uses only a single display system of the type described herein. Such display system may be located in proximity to an eye for direct viewing. Alternatively, such display system may be used as part of a projection type display in which light from the display system is projected onto a surface where the image is formed for viewing. Various lenses and/other optical components may be used to direct from the display system light to create an appropriate image at a desired location. Turning to Figs. 53-58, operation of the apparatus is described. In Fig. 53 a plan view of a dot matrix liquid crystal display is shown. The shade of grey measured at several pixels is indicated. According to die bottom graph in Fig. 53, the actual hade is shown; according to die dot matrix image at the side and top of Fig. 53, the actual shade of die pixel is shown. Thus, at location 1 on the graph at the bottom of Fig. 53, there is a shade 2. At location 2, there is a shade 1. At location 3 there is a shade 0, and so on. In pixel 1 marked in die top of Fig. 53, die pixel is a shade gray of 2; and at die adjacent pixel the pixel is a shade gray of 1, and so on. This is conventional. This would indicate the signals coming in to tiie computer control 905. In Fig. 54, an example of a bright image scene produced by back light at a medium (normal) illumination level is illustrated at die top; die shades of gray are shown at the middle left; and die lamp light level is constant at tiie bottom left. The viewer sees a bright/low contrast image of a person as seen at the top right of the drawing. A side view of die display representing respective pixels and die tray levels thereof is shown at the bottom right of the figure. Fig. 55 is similar to Fig. 54 again with average constant lamp light level. The average light level is produced; die average brighmess ouφut from the display is to be produced; and die viewer sees an average brighmess high contrast image because all conditions are optimized. Fig. 56 is similar to Fig. 54 again with average constant lamp light level and a dark transmission provided by the liquid crystal cell; die viewer sees a dim low contrast image. Figs. 54-56 represent operation of a standard display apparatus. Figs. 57 and 58 represent applying die principles of the present invention to develop high contrast images. In Fig. 57 it is seen that there is the intent to produce a wide range of gray levels; and this is possible by using a high intensity lamp level; the result is a bright high contrast image. In Fig. 58 it is intended that the viewer see a dim image; the same range of grey shades are provided as is depicted in die middle left graph of die drawing; but die lamp level is low. Therefore, there is a good contrast ratio provide to die viewer; from 0 to about 7 at the brighmess level shown in the graph at the upper left of the drawing.

Claims: CLAIMS The embodiments of die invention in which an exclusive property or privilege is claimed are set forth in the following claims: 1. A device for shifting the location of an optical signal, comprising birefringent means for selectively refracting light based on optical polarization characteristic of the light, and means for changing such optical polarization characteristic of light, said birefringent means and said means for changing being cooperative to shift die location of the optical signal. 2. A system for increasing the resolution of an optical display having a plurality of picture elements, comprising birefringent means for selectively refracting light based on polarization characteristics of the light, changing means for selectively changing the polarization characteristics of light, and said birefringent means and said changing means being in optical series and cooperative in response to selective operation of said changing means to change die location of ouφut optical signals therefrom. 3. A display system, comprising a display for producing visual ouφut information by selective operation of a plurality of picture elements at respective locations, and means for changing die location of the ouφut information as a function of optical polarization thereby effectively to increase the number of picture elements. 4. A display system, comprising a display for producing visual ouφut information by selective operation of a plurality of picture elements at respective locations, and means for changing die location of the ouφut information without physical realignment of a mechanical device thereby effectively to increase die number of picture elements. 5. A display system, comprising a display for producing visual ouφut information by selective operation of a plurality of picture elements at respective locations, and means for electro-optically changing the location of tiie ouφut information thereby effectively to increase die number of picture elements. 6. A method for displaying visual information, comprising presenting a first optical ouφut from a source by providing plural optical signals arranged in a pattern, presenting a second optical ouφut from the source by providing plural optical signals arranged in a pattern, and selectively shifting the location of the pattern of the second optical ouφut relative to the location of tiie patten of the first optical ouφut based on optical polarization. 7. An electro-optical didiering system for shifting polarized light, comprising birefringent means for selectively refracting light as a function of a polarization characteristic of the light, and changing means for changing the polarization characteristic of polarized light to provide ouφut light tiiat is shifted or not as a function of optical polarization. 8. A method of making a display, comprising, positioning in optical series an image source, a birefringent means for selectively refracting light based on optical polarization characteristic of the light, and a changing means for changing such optical polarization characteristic. 9. The device of claim 27, further comprising a display for supplying an image as such optical signal, and wherein said display includes means for producing visual ouφut information as such optical signal by selective operation of a plurality of picture elements at respective locations, and said means for changing and birefringent means being cooperative to change die location of die ouφut information without physical realignment of a mechanical device thereby effectively to increase the number of picture elements. 10. The device of claim 1 , wherein such optical polarization characteristic comprises the direction of plane of polarization of light, and said means for changing comprises means for selectively changing the direction of such plane of polarization. 11. The device of claim 1 , wherein said birefringent means comprises means for altering the direction of light transmitted therein based on die direction of plane of polarization of light transmitted therethrough. 12. The device of claim 1 , wherein said birefringent means comprises means for directing light transmitted therein in different respective light paths depending on die optical polarization characteristic of the transmitted light. 13. The device of claim 1, said birefringent means comprising means for resolving light into two components respectively having orthogonal planes of polarization. 14. The device of claim 13, said birefringent means comprising means for deflecting one of such components. 15. The device of claim 14, said birefringent means comprising means for transmitting one of such components substantially without deflection. 16. The device of claim 1, wherein such optical signal forms an image, and said birefringent means and means for changing are cooperative physically to displace at least part of such image. 17. The device of claim 1, wherein such optical signal forms an image, and said birefringent means and means for changing are cooperative periodically to displace at least part of such image to increase tiie resolution thereof. 18. The device of claim 17, further comprising means for operating said means for changing periodically for cooperation witii said birefringent means to effect interdigitation of portions of such image. 19. The device of claim 1, wherein such optical signal forms an image, and further comprising means for operating said means for changing periodically for cooperation with said birefringent means to effect interdigitation of portions of such image. 20. The device of claim 1, said birefringent means and said means for changing being s in optical series. 21. The device of claim 20, said means for changing being optically upstream from said birefringent means. 22. The device of claim 20, said means for changing being optically downstream from said birefringent means. 23. The device of claim 22, wherein such optical polarization characteristic comprises the direction of plane of polarization of light, said means for changing comprises means for selectively changing the direction of such plane of polarization, and further comprising an analyzer optically downstream from said means for changing and said birefringent means for discriminating between light based on plane of polarization to transmit or to block transmission of light based on such discrimination. 24. The device of claim 23, said birefringent means comprising means for resolving incident unpolarized light into two components respectively having orthogonal planes of polarization. 25. The device of claim 1, further comprising means for supplying plane polarized light as such optical signal. 26. The device of claim 1, further comprising means for supplying unpolarized light as such optical signal. 27. The device of claim 1, further comprising a display for supplying an image as such optical signal. 28. The device of claim 27, said display comprising a light emissive display. 29. The device of claim 28, said display comprising a cathode ray tube. 30. The device of claim 29, further comprising means for operating said means for changing periodically for cooperation with said birefringent means to effect interdigitation of portions of such image. 31. The device of claim 27, said display comprising a display having optical dead space. 32. The device of claim 31, further comprising means for operating said means for changing periodically for cooperation with said birefringent means to effect shifting of portions of such image to cover dead space of such display. 33. The device of claim 27, said display comprising a liquid crystal display. 34. The device of claim 1, said birefringent means comprising means to effect double refraction. 35. The device of claim 1, said birefringent means comprising crystal material. 36. The device of claim 35, said birefringent means comprising calcite. 37. The device of claim 1 , said birefringent means comprising crystal having axes such that plane polarized light transmitted in such crystal is deflected or is transmitted without deflection depending on die relationship of the direction of plane of polarization to the direction of such axes. 38. The device of claim 37, said birefringent means having a pair of generally parallel faces, respectively for receiving an input optical signal and for transmitting at least one ouφut optical signal at a location depending on die plane of polarization of light of such ouφut optical signal, and wherein die directions of such axes are non-parallel with the planes of said parallel faces. 39. The device of claim 37, said means for changing comprising a birefringent liquid crystal cell having an axis, and wherein the axis of said liquid crystal cell and die projection of the axes of said birefringent means are effectively relatively positioned at 45 degrees to each other. 40. The device of claim 39, further comprising means for supplying plane polarized light as such optical signal. 41. The device of claim 40, said means for supplying comprising a liquid crystal display. 42. The device of claim 40, said means for supplying comprising a plane polarizer having a plane of polarization oriented effectively relatively at 45 degrees to die axis of said liquid crystal cell. 43. The device of claim 40, wherein said means for supplying comprises means for supplying light in die visible spectrum. 44. The device of claim 1, said means for changing comprising a liquid crystal cell. 45. The device of claim 44, said liquid crystal cell comprising a twisted nematic liquid crystal device. 46. The device of claim 44, said liquid crystal cell comprising a birefringent liquid crystal device. 47. The system of claim 2, wherein such display is operative to produce an image, and further comprising means for operating said changing means periodically for cooperation with said birefringent means to effect interdigitation of portions of such image. 48. The system of claim 2, wherein die display is operative to produce an image and die display has dead space in respective picture elements, and further comprising means for operating said changing means periodically for cooperation with said birefringent means to effect shifting of portions of such image to cover dead space of such display. 49. The device of claim 48, wherein die display comprises a liquid crystal display. 50. The device of claim 2, wherein the display comprises a liquid crystal display. 51. The system of claim 7, said birefringent means comprising means to effect double refraction. 52. The system of claim 7, said birefringent means comprising crystal material. 53. The system of claim 52, said birefringent means comprising calcite. 54. The system of claim 7, said birefringent means comprising crystal having axes such that plane polarized light transmitted in such crystal is deflected or is transmitted without deflection depending on die relationship of die direction of plane of polarization to tiie direction of such axes. 55. The system of claim 54, said birefringent means having a pair of generally parallel faces, respectively for receiving an input optical signal and for transmitting at least one ouφut optical signal at a location depending on die plane of polarization of light of such ouφut optical signal, and wherein the directions of such axes are non-parallel with the planes of said parallel faces. 56. The system of claim 54, said means for changing comprising a birefringent liquid crystal cell having an axis, and wherein the axis of said liquid crystal cell and die projection of die axes of said birefringent means are effectively relatively positioned at 45 degrees to each otiier. 57. The system of claim 56, further comprising means for supplying plane polarized light as such optical signal. 58. The system of claim 57, said means for supplying comprising a liquid crystal display. 59. The system of claim 57, said means for supplying comprising a plane polarizer having a plane of polarization oriented effectively relatively at 45 degrees to die axis of said liquid crystal cell. 60. The system of claim 57, wherein said means for supplying comprises means for supplying light in die visible spectrum. 61. The system of claim 7, said means for changing comprising a liquid crystal cell. 62. The system of claim 61, said liquid crystal cell comprising a twisted nematic liquid crystal device. 62. The system of claim 61 , said liquid crystal cell comprising a birefringent liquid crystal device. 63. The method of claim 8, further comprising selecting such birefringent means as a crystal having respective axes aligned to resolve light into respective components having different respective planes of optical polarization. 64. The method of claim 63, said selecting comprising selecting such birefringent means as calcite. 65. The method of claim 63, further comprising selecting such changing means as a liquid crystal device. 66. The method of claim 65, further comprising selecting such liquid crystal device as a birefringent liquid crystal device, and orienting die axis of such liquid crystal device at effectively 45 degrees to die axes of such birefringent means. 67. The method of claim 8, further comprising positioning such changing means optically upstream of such birefringent means. 69. The method of claim 8, further comprising positioning such changing means optically downstream of such birefringent means. 70. The method of claim 69, further comprising positioning an optical polarization analyzer optically downstream of such changing means. 71. The device of claim 27, wherein said display includes means for producing as such optical signal visual ouφut information by selective operation of a plurality of picture elements at respective locations, and said means for changing and birefringent means are cooperative to change die location of tiie ouφut information as a function of optical polarization thereby effectively to increase the number of picture elements. 72. The device of claim 27, wherein said display comprises a display for producing visual ouφut information as such optical signal by selective operation of a plurality of picture elements at respective locations, and said means for changing and birefringent means comprising means for electro- optically changing the location of die ouφut information thereby effectively to increase the number of picture elements. 73. A method of using a display made according to die method of claim 8 for displaying visual information, comprising presenting a first optical ouφut from a source by providing plural optical signals arranged in a pattern, presenting a second optical ouφut from the source by providing plural optical signals arranged in a pattern, and selectively shifting the location of the pattern of the second optical ouφut relative to the location of tiie patten of the first optical ouφut based on optical polarization. 109a 74. Apparatus for changing direction of an optical signal, comprising double refraction means for refracting an optical signal based on a characteristic of such optical signal to change the direction of die optical signal, and means for changing such characteristic to determine whether such direction is changed. 75. The apparatus of claim 74, said double refraction means and said means for changing being in optical series. 76. The apparatus of claim 75, said double refraction means and said means for changing being in optical series between a source of optical signal and an ouφut at which die optical signal is provided as an optical ouφut, and being cooperative to change the location of the optical signal at such ouφut. 77. The apparatus of claim 74, said double refraction means comprising calcite crystal. 78. The apparatus of claim 74, said double refraction means comprising liquid crystal material. 79. The apparatus of claim 78, said liquid crystal material comprising liquid crystal polymer. 80. The apparatus of claim 74, said double refraction means comprising liquid crystal material, and said means for changing comprising means for changing a characteristic of the liquid crystal material relative to the optical signal incident thereon thereby effectively to change such characteristic of the optical signal relative to such double refraction means. 81. The apparatus of claim 80, said means for changing comprising means for changing alignment of liquid crystal material relative to transmission direction of light transmitted therethrough. 82. The apparatus of claim 74, said means for changing comprising a liquid crystal cell. 83. The apparatus of claim 82, said liquid crystal cell comprising a twisted nematic liquid crystal cell. 84. The apparatus of claim 82, said liquid crystal cell comprising a birefringent liquid crystal cell. 85. The apparatus of claim 82, said means for changing comprising a plurality of liquid cells in optical series. 86. The apparatus of claim 74, said double refraction means and changing means comprising means for selectively changing die location of an optical ouφut signal between plural locations. 87. The apparatus of claim 86, said double refraction means and changing means comprising means for selectively changing the location of an optical ouφut signal between plural locations located on a common axis. 88. The apparatus of claim 86, said double refraction means and changing means comprising means for selectively changing die location of an optical ouφut signal between plural locations located on plural respective axes. 89. The apparatus of claim 88, said double refraction means and changing means comprising means for selectively changing the location of an optical ouφut signal between plural locations located on plural respective non-parallel axes. 90. The apparatus of claim 88, said double refraction means and changing means comprising means for selectively changing the location of an optical ouφut signal between plural locations located on plural respective orthogonal axes. 91. An optical display system comprising an optical display and die apparatus of claim 1, said apparatus being positioned relative to die optical display selectively and sequentially to change the location of optical ouφut signals from the display to enhance the resolution of the display. 92. The system of claim 91, said optical display comprising a CRT. 93. The system of claim 91, said optical display comprising an LCD. 94. The system of claim 93, said LCD comprising an active matrix LCD. 95. A method of electro-optically didiering an optical signal, comprising selectively refracting an optical signal based on a characteristic of such optical signal to change the direction of the optical signal, and selectively changing such characteristic to determine whether such direction is changed and die location of tiie ouφut optical signal. 96. The method of claim 95, said selectively changing comprising sequentially and periodically changing such characteristic. 97. The method of claim 95, said selectively changing comprising sequentially and periodically changing such characteristic to change the location of the optical ouφut signal between two locations. 98. A method of displaying optical information, comprising providing a plurality of optical signals ouφut from an optical display, selectively refracting respective optical signals based on a characteristic of such optical signals to change die direction of die optical signal, and selectively changing such characteristic to determine whether such direction is changed thereby to determine the location of the ouφut optical signals. 99. A metiiod of covering optical dead space in an optical display, comprising providing a plurality of optical signals ouφut from an optical display witii optical dead space between respective optical signals, selectively refracting respective optical signals based on a characteristic of such optical signals to change the direction of the optical signal, and selectively changing such characteristic to determine whether such direction is changed thereby to determine die location of the ouφut optical signals to cover such optical dead space. 109b 100. A display system, comprising: an optical display for producing an image; and first birefringent means for refracting one component of the image relative to a second component of die image based on polarization characteristics of said components to produce a plurality of adjacent images. 101. The system of claim 100, wherein said optical display produces linearly polarized light. 102. The system of claim 100, wherein said optical display produces nonpolarized light. 103. The system of claim 102, including a linear polarizer interposed between said display and said first birefringent means. 104. The system of claim 100, including a second birefringent means for selectively refracting one component of each of the images produced by said first birefringent means relative to a second component of each of die images based on polarization characteristics of said components to produce an additional plurality of adjacent images. 105. The system of claim 104, including a wave plate interposed between said first and second birefringent means. 106. A display system, comprising: an optical display including a plurality of pixels witii optical dead space between said pixels for producing an image; and birefringent means for shifting one polarization component of the image relative to a second polarization component of tiie image such that said shifted polarization component lies in said dead space. 107. The system of claim 106, wherein said optical display produces linearly polarized light. 108. The system of claim 106, wherein said optical display produces nonpolarized light. 109. The system of claim 108, including a linear polarizer interposed between said display and said first birefringent means. 110. The system of claim 108, including a second birefringent means for selectively shifting one component of each of die images produced by said first birefringent means relative to a second component of each of the images based on polarization characteristics of said components to produce an additional plurality of adjacent images. 111. The system of claim 110, including a wave plate interposed between said first and second birefringent means. 112. A method of reducing optical background noise, comprising the steps of: displaying a plurality of pixels witii optical dead space between said pixels for producing an image; and shifting one polarization component of tiie image relative to a second polarization component of the image such that said shifted polarization component lies in said dead space. 109c: 113. A display system, comprising: an optical display for producing an image; and first birefringent means for refracting one component of the image relative to a second component of die image based on polarization characteristics of said components to produce a plurality of adjacent images. 114. The system of claim 113 , wherein said optical display produces linearly polarized light. 115. The system of claim 113, wherein said optical display produces nonpolarized light. 116. The system of claim 115, including a linear polarizer interposed between said display and said first birefringent means. 117. The system of claim 113, including a second birefringent means for selectively refracting one component of each of die images produced by said first birefringent means relative to a second component of each of the images based on polarization characteristics of said components to produce an additional plurality of adjacent images. 118. The system of claim 117, including a wave plate interposed between said first and second birefringent means. 119. A display system, comprising: an optical display including a plurality of pixels with optical dead space between said pixels for producing an image; and birefringent means for shifting one polarization component of die image relative to a second polarization component of die image such tiiat said shifted polarization component lies in said dead space. 120. The system of claim 119, wherein said optical display produces linearly polarized light. 121. The system of claim 119, wherein said optical display produces nonpolarized light. 122. The system of claim 121 , including a linear polarizer interposed between said display and said first birefringent means. 123. The system of claim 121, including a second birefringent means for selectively shifting one component of each of the images produced by said first birefringent means relative to a second component of each of die images based on polarization characteristics of said components to produce an additional plurality of adjacent images. 124. The system of claim 123 , including a wave plate interposed between said first and second birefringent means. 125. A method of reducing optical background noise, comprising die steps of: displaying a plurality of pixels with optical dead space between said pixels for producing an image; and shifting one polarization component of the image relative to a second polarization component of the image such that said shifted polarization component lies in said dead space. 12Sι " " 126. A method for coordinating control of a display system to coordinate optical switching to provide multicolor ouφut light. 127. A method of coordinating light transmission as a function of time by switching the pixel between dark and clear states relative to the switching time of the pixel. 128. A method of coordinating operation of a display, comprising operating the pixel between less than maximum clear and dark states, and didiering the optical signal. 129. A method of coordinating an electronic didiering system with the switching time of a liquid crystal display. 130. The method of claim 129, said coordinating comprising controlling time as a function of improved crispness and sharpness of the image. 131. A method of coordinating operation of an electronic didiering system witii a liquid crystal cell to introduce phase shifts to change light transmission or polarization as a function of change in a prescribed input. 132. A method of displaying multicolor, comprising directing light from plural locations in a display into superimposed relation. 133. A metiiod of displaying multicolor images, comprising superimposing one color pixel on another color pixel. 134. The method of claim 133, wherein the superimposing is of a ditiiered image of a pixel and an undithered pixel. 135. The method of claim 133, wherein die superimposing is of a ditiiered image of a pixel and a ditiiered image of another pixel.

Inventors: FERGASON JAMES L, FERGASON, JAMES, L.
Applicants: FERGASON JAMES L, FERGASON, JAMES, L.
Application year: 1995
Main classification: G02B5
IPC codes: G02B5, G02F1, G09G3, H01J29, H04N5, H04N9, H04N13