Abstract:
A display system includes a mechanism to provide for simultaneous pixelated color with a spatial light modulator. Also included is a mechanism to project the simultaneous pixelated color to create a color field display on a viewing surface. A further mechanism moves the color field display relative to viewing surface to provide at least one of color and resolution increasing wobulation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation in part of commonly assigned U.S. patent application Ser. No. 10/969,412, filed Oct. 20, 2004, and is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     A conventional system or device for displaying an image, such as a display, projector, or other digital imaging system, is frequently used to display a still or video image on a display surface, such as a display screen. Viewers evaluate display systems based on many criteria such as image size, color gamut, contrast ratio, brightness and resolution, for example. Image brightness, pixel color accuracy, and resolution are particularly important metrics in many display markets because the available brightness, color gamut and resolution can limit the size of a displayed image and control how well the image can be seen in venues having high levels of ambient light.  
         [0003]     Many digital display systems create a full color display with a single light modulator by creating three or more modulated images in primary colors (red, green, and blue) per video frame. The primary colors are typically derived by passing a white light through a color wheel, prism, or some other color filter before causing the light to impinge the modulator. Sometimes, the white light is passed through a spatial light homogenizer after the color wheel to even out the intensity of the light over the area striking the modulator. The modulated images are sequentially displayed at a high rate so as to create a full color image in the human visual system. Thus, this method of generating a full color display is called “sequential color.” 
         [0004]     Color wheels add noise, thickness, expense, and complexity to a display system for a variety of reasons, including the inherent long-term reliability problems associated with moving mechanical parts. The embodiments described herein were developed in light of these and other drawbacks associated with known display systems. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]     The invention is better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. Rather, emphasis has instead been placed upon clearly illustrating the invention. Furthermore, like reference numerals designate corresponding similar parts through the several views.  
         [0006]      FIG. 1  is an exemplary block diagram of a display system according to one embodiment of the invention.  
         [0007]      FIG. 2  is an exemplary partial view of a spatial light modulator illustrating a triangular based color scheme used in one embodiment of the invention.  
         [0008]      FIG. 3  is an exemplary diagram of a triangular wobulated shift pattern in one embodiment of the invention.  
         [0009]      FIG. 4  is an exemplary timing diagram of a frame period for one pixel location on a viewing surface used in one embodiment of the invention.  
         [0010]      FIG. 5  is an exemplary partial view of a spatial light modulator illustrating an adjacent neighbor based color scheme used in one embodiment of the invention.  
         [0011]      FIG. 6  is an exemplary diagram of an adjacent neighbor wobulated shift pattern in one embodiment of the invention.  
         [0012]      FIG. 7  is an exemplary timing diagram of a frame period for one pixel location on a viewing surface used in one embodiment of the invention.  
         [0013]      FIG. 8  is an exemplary partial view of a spatial light modulator illustrating a rectangular based color scheme used in one embodiment of the invention.  
         [0014]      FIG. 9  is an exemplary diagram of a rectangular wobulated shift pattern in one embodiment of the invention.  
         [0015]      FIG. 10  is an exemplary timing diagram of a frame period for one pixel location on a viewing surface used in one embodiment of the invention.  
         [0016]      FIG. 11  is an exemplary partial view of a spatial light modulator illustrating an alternative triangular based color scheme used in one embodiment of the invention.  
         [0017]      FIG. 12  is an exemplary diagram of an alternative triangular wobulated shift pattern in one embodiment of the invention.  
         [0018]      FIG. 13  is an exemplary timing diagram of a frame period for one pixel location on a viewing surface used in one embodiment of the invention.  
         [0019]      FIG. 14  is an exemplary partial view of a spatial light modulator illustrating an alternative rectangular based color scheme with resolution enhancement used in one embodiment of the invention.  
         [0020]      FIG. 15  is an exemplary diagram of an alternative rectangular wobulated shift pattern with resolution enhancement in one embodiment of the invention.  
         [0021]      FIG. 16  is an exemplary timing diagram of a frame period for one pixel location on a viewing surface used in one embodiment of the invention.  
         [0022]      FIG. 17  is an exemplary partial view of a spatial light modulator illustrating an alternative rectangular based color scheme used in one embodiment of the invention.  
         [0023]      FIG. 18  is an exemplary diagram of an alternative triangular wobulated shift pattern in one embodiment of the invention.  
         [0024]      FIG. 19  is an exemplary timing diagram of a frame period for one pixel location of a viewing surface used in one embodiment of the invention.  
     
    
     DETAILED DESCRIPTION  
       [0025]     The embodiments described herein provide a full-fill projected image on a viewing surface using one color or interferometric modulator whose individual pixel elements cannot provide a full range of primary colors. The following embodiments allow for a low cost, robust, and single modulator display system without the need of a color wheel. In one embodiment, a projection system uses an interferometric-based light modulator to generate color pixels on a viewing surface. The light modulator is “digital” in the sense that each pixel element on the modulator generates one or two non-black colors. However, adjacent pixel elements have complementary primary colors. The modulator image is “wobulated” or otherwise spatially shifted such that the projected modulated pixels are displayed in an overlapped fashion on the viewing surface, allowing for each pixel location on the viewing surface to have a full range of primary colors such that each is capable of creating a perceived white pixel. Stated otherwise, a wobulation control circuit controls the displacement of the pixels generated by modulator on the viewing surface such that each pixel location on the viewing surface allows all primary colors to be generated.  
         [0026]     For the purposes of this application, a perceived pixel is defined as a spot of light formed on the viewing surface. The location of a pixel is defined by the coordinates of the centroid of the pixel outline. A pixel element is an element on the light modulator that receives light from the light source, modulates the spectral (e.g. wavelength, frequency, and optionally incorporating intensity) distribution of the light, and defines at least one perceived pixel on the viewing surface. A primary color is defined by a limited spectral range within the visible light spectrum of the light source. A perceived pixel having a primary color is a spot of light characterized in that the pixel has a narrow spectral distribution that defines the primary color of the spot. A pixel array having interleaved pluralities of pixels is an array of spots characterized in that the array includes a first plurality of spots having a first primary color and a second plurality of spots having a second primary color and that the first and second primary colored spots form a known, preferably repeating, pattern. To spectrally modulate is to receive broadband wavelengths of light from a light source and to change the spectral distribution of the light source to narrow bands of wavelengths.  
         [0027]      FIG. 1  is an exemplary block diagram of a display system  10  incorporating a pixelated color management device that incorporates different aspects of the invention. For instance the display system  10  includes an image processing unit  12  that receives image data  11  in analog or digital form and converts the data accordingly for processing. The image processing unit  12  may be implemented as a microcontroller, a digital signal processor, or general purpose CPU using a combination of logic and software or firmware. Alternatively, the image processing unit can be hard coded logic implemented in discrete or integrated circuits. The display system  10  includes a light source  14  that illuminates a color pixel spatial light modulator (SLM)  16 . The light source  14  may include a high pressure arc-source, such as mercury vapor or xenon, or may include a solid state device including one or more semiconducting or organic LEDs. Alternatively, the light source  14  may include of one or more laser sources. The light source  14  will generally include a mechanism or optics to spatially homogenize the light such that it will be uniform in irradiance when projected onto the color pixel SLM  16 . The color pixel SLM  16  has a plurality of individual pixels formed in an array such that each pixel is able to filter or otherwise spectrally modulate the light from the light source to provide one or more primary colors. In this example, the individual pixels are spatially distributed on the color pixel SLM  16  such that a color scheme is formed whereby neighboring pixels provide for complementary primary colors. In another example, the individual pixels are assigned a color by how they are controlled.  
         [0028]     The light coming off the color pixel SLM  16  is controlled by wobulation device  18  before being transmitted or projected onto a viewing surface  20 . The wobulation device  18  is controlled by the image processing circuit  12  to create a wobulation control circuit. The image processing unit  12  controls the light source  14 , the color pixel SLM  16  and the wobulation device  18  in conjunction to place one or more frames of the received image data  11  on the viewing surface  20 . The wobulation device  18  is able to spatially shift the image or array of pixels from the color pixel SLM  16  in one or more directions in either fill or partial (such as ½ pixel) increments to allow the individual pixels of the color pixel SLM  16  to overlap fully or partially on the viewing surface  20 .  
         [0029]     The color pixel SLM  16  is characterized in that each of its individual pixel elements are able to spectrally modulate the received light from the light source  14  and create at least one, perhaps two, or more narrow bands of light. One exemplary modulator is an interferometric modulator such as that found in U.S. patent Ser. No. 10/428,261, filed Apr. 30, 2003, and incorporated herein by reference. Another color pixel SLM modulator is an LCD panel that incorporates a color filter such that a color scheme is defined across the SLM array. Such LCD panels are available from several suppliers known to those of skill in the art. Another color pixel SLM modulator is liquid crystal on silicon (LCOS) which is available from several suppliers known to those of skill in the art. A diffractive based modulator such as that described in commonly assigned U.S. Pat. No. 6,747,785, may also be used as color pixel SLM  16 . Alternatively, an active color pixel SLM can be used such as with an array of LED&#39;s or laser diodes. In this embodiment, the light source  14  and the color pixel SLM  16  are combined to form the active color pixel SLM.  
         [0030]     A “pixel generator”  15  is a functional combination of the light source  14  and the SLM  16 . Absent operation of wobulation device  18 , the pixel generator  15  generates an array of pixels (colored spots of light) on the viewing surface  20 . The array pixels include pixels having two or more primary colors that are displayed simultaneously and have a repeating pattern. Examples of such repeating patterns will become apparent in the discussions with respect to  FIGS. 2-19 . In one example, the repeating pattern might be red (R), green (G), blue (B), red, green, blue, etc. going in a particular direction. Absent operation of the wobulation device  18 , the pixel generator cannot generate all primary colors at each pixel location and hence each primary color has a “depleted pattern” or a pixel pattern having incomplete coverage of viewing surface  20 . In this one example, red only covers about on third of the area of the viewing surface  20 . This may provide a severe “screen door” affect as well as providing only one third the areal resolution of the overall pixel array for that primary color. The wobulation device  18  displaces the pixels during a viewing period such as a frame period so that each primary color can more effectively cover the viewing surface  20  or more effectively address the locations on the viewing surface  20 .  
         [0031]     The wobulation device  18  may be formed of one or more optical shifting elements in a projection lens or as an adjustable refractive element. Alternatively, the wobulation device  18  may be a reflective component such as a rotatable, tilting, or movable mirrored surface. In general, the wobulation device can be any component that is able to move or bend the optical path of the image projected from the color pixel SLM  16  to create wobbling optics. Another wobulation device is a mechanical shifter that holds the color pixel SLM  16  and physically shifts the color pixel SLM  16  in one or more directions rather than its projected image. If the color pixel SLM  16  is physically shifted, the light source  14  may need to be designed to slightly overfill the array of pixels on the color pixel SLM  16  to account for such movement. Several different forms of wobulation devices are shown and described in commonly assigned US Patent Publication 2004-0027313A1, Ser. No. 10/242,545, filed Sep. 11, 2002 and hereby incorporated by reference.  
         [0032]     The viewing surface  20  may be one of several different types and technologies. For instance, the viewing surface  20  may be a front projection screen, a rear projection screen, a video screen, or an appropriate reflective or transmissive surface such as a wall or paper.  
         [0033]      FIG. 2  is an exemplary diagram of a portion of a color pixel SLM  16 A in which the pixel elements  22 ,  24 , and  26  are spatially distributed in a color scheme that is laid out in a triangular fashion that repeats over the pixel array. In this example, first pixel element  22  defines a red (R) pixel color primary, second pixel element  24  defines a green (G) pixel color primary, and third pixel element  26  defines a blue (B) pixel color primary. Each of the pixels may be turned off to a black (K) state. Different intensity levels of the colors can be provided by varying the amount of time a pixel is in the on or off state, such as by pulse width modulation.  
         [0034]     Absent a wobulation device  18 , the color pixel SLM  16 A produces a pixel pattern on the screen approximately matching the pattern depicted in  FIG. 2 . As is seen, each primary color is depleted to about one third of full areal coverage (and slightly or more depending on the size of each pixel relative to locational pixel boundaries).  
         [0035]      FIG. 3  is an exemplary diagram of the movement of a pixel element as it is projected onto the viewing surface  20 . For instance, first pixel element  22  would be displayed at a first pixel location at first position  30  on the viewing surface  20  during one portion of an image frame period. For a frame period of 1/60 of a second, the first position  30  would be occupied by first pixel element  22  for approximately 1/100 th  of a second. During the next portion of the image frame period, the first pixel element  22  would be shifted by the wobulation control circuit  18  to occupy the second position  32  which is a second pixel location on the viewing surface  20 . This position would be held for about 1/180 th  of a second before the wobulation control circuit  18  shifts the first pixel element  22  to a third pixel location  34  on the viewing surface  20 . The position would be held for 1/180 th  of a second before being shifted by the wobulation control circuit  18  back to the first position  30 . The intensity of the perceived pixel on the viewing surface can be controlled by adjusting the amount of time that the first pixel element  22  is actually enabled or activated while it occupies a particular pixel location on the viewing surface. For instance, the first pixel element  22  can be pulse width modulated to have a duty cycle of 50% to have one half of the full intensity while positioned at first position  30 . To have a color depth of 8 bits, the first pixel element  22  would need to be controllable to have an off/on state of 1/256 th  of 1/180 th  of a second or 1/46,080 th  of a second (about 21 microseconds) for a 60 frames per second (fps) video.  
         [0036]     In some embodiments, spatial and/or temporal dithering of the pixel elements can be used to improve the image quality in such embodiments where the bit depth of the data controlling the pixel is not a large as desired. Alternatively, the pixel elements can be jittered or rotated rather than just being statically fixed after being shifted to a position. Another embodiment allows the pixel elements to be continually modulated based on their position even between the different positions.  
         [0037]     By utilizing the displacement of the pixel elements as depicted and discussed with respect to  FIG. 3 , essentially full area coverage of the viewing area is provided for each primary color. Stated another way, each of pixel elements  22 ,  26 , and  26  that display red, green, and blue respectively, can address multiple pixel locations on the viewing screen to reduce or eliminate primary color depletion.  
         [0038]      FIG. 4  is an exemplary timing diagram showing the timing of a respective perceived pixel on the viewing surface to generate a full-on white pixel during a single image frame period. The modulator pixels can of course be modulated between the stated color and black to create a perceived pixel of many possible colors. During the first sub-period  36 , the perceived pixel location has a red pixel such as first pixel  22  projected onto the pixel location. The first pixel  22  can be modulated appropriately during this sub-period  36  to achieve a desired intensity. During the second sub-period  38 , the second pixel element  24 , a green pixel is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. Again, during this sub-period  38 , the second pixel element  24  can be appropriately modulated to provide a desired green intensity level. During the third sub-period  40 , third pixel element  26 , a blue pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. The third pixel element  24  can be appropriately modulated to provide a desired blue intensity level by turning the color on or off (that is, off being a black state).  
         [0039]     By utilizing the displacement of the pixel array, locations on the viewing surface may be more completely addressed with all three primary colors. This eliminates a tendency of a particular single perceived pixel location to only be able to display red or black for instance. In the example discussed with respect to  FIG. 4 , a white pixel is perceived when all three primary colors are properly enabled in sequence for a particular pixel location.  
         [0040]      FIG. 5  is an exemplary pixel element layout showing an alternative color scheme of a color pixel SLM  16 B using a adjacent pixel approach to providing colors in which at least one of the adjacent pixels can support the creation of two non-black primary colors. For instance, first pixel element  42  can create red (R) or black (K) states while the second pixel element  44  is able to generate green (G), blue (B), or black (K) states.  
         [0041]      FIG. 6  is an exemplary diagram of the movement of a pixel element as it is projected onto the viewing surface  20  for the color pixel SLM  16 B of  FIG. 5 . For instance, first pixel element  42  would be displayed at a first pixel location at first position  46  on the viewing surface  20  during one portion of an image frame period. In one example (see  FIG. 7 ), for a frame period of 1/60 th  of a second, the first position  46  would be occupied by first pixel element  42  for about 1/120 th  of a second. During the next portion of the image frame period, the first pixel element  42  would be shifted by the wobulation control circuit  18  to occupy the second position  48  which is a second pixel location on the viewing surface  20 . This position would be held for about 1/120 th  of a second before the wobulation control circuit  18  shifts the first pixel element  42  back to the first pixel location  46  on the viewing surface  20 . The intensity of the perceived pixel on the viewing surface can be controlled by adjusting the amount of time that the first pixel element  42  is actually enabled while it occupies a particular pixel location on the viewing surface. For instance, the first pixel element  42  can be pulse width modulated with a duty cycle of 25% to have one-forth of the full intensity while positioned at first position  46 . To have a color depth of 8 bits, the first pixel element  42  would need to be controllable to have an off/on state of 1/256 th  of 1/120 th  of a second or 1/30,720 th  of a second (about 32 microseconds) for a 60 fps video.  
         [0042]     For the second pixel element  44 , since it generates two primary colors during the 120 th  of a second interval that it is held at either the first position  46  or the second position  48 , its operates at twice the speed of the first element  42  which only supports one red color in order to support equal color bit depths for a full white perceived pixel. Thus, the second pixel element  44  could display a green color during the first 1/240 th  of a second of a sub-period interval, and a blue color during that second 1/240 th  of a second of the sub-period interval.  
         [0043]     For example,  FIG. 7  illustrates an exemplary timing diagram of a respective perceived pixel on the viewing surface  20  during a single image frame period for this embodiment. During the first sub-period  50 , the perceived pixel location has a red pixel such as first pixel  42  projected onto the pixel location. The first pixel  42  can be modulated appropriately during this first sub-period  50  to achieve a desired intensity. During the second sub-period  52 , the second pixel element  44  creates a green pixel positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location of the viewing surface. Again, during this second sub-period  52 , the second pixel element  44  can be appropriately modulated to provide a desired green intensity level. During the third sub-period  54  the second pixel element  44  creates a blue pixel onto the perceived pixel location of the viewing surface  20 . The second pixel element  44  can be appropriately modulated to provide a desired blue intensity level by turning the color on or off.  
         [0044]     The timing of the wobulation shifting shown in  FIG. 7  is particularly useful with a red-deficient light source such as a high pressure mercury vapor arc-source light source. This increased timing for the red period allows for the more red light from the light source to be placed on the viewing surface at the expense of overall brightness.  
         [0045]     Alternatively, if one wishes to balance the gamut and the brightness, a color scheme which incorporates a white pixel as shown in  FIG. 8  may be used.  FIG. 8  is a partial view of an array of pixel elements in a color pixelated SLM  16 C which has at least one white pixel element along with the primary color elements. For instance, color pixelated SLM  16 C has a first pixel element  60  which is capable of generating a black (K) or blue color, a second pixel element  62  which is capable of generating a black or red color, a third pixel element  66  which is capable of generating a black or white (W) (such as unfiltered) light, and a fourth pixel element  64  which is capable of generating a black or green color.  
         [0046]      FIG. 9  is an exemplary diagram of the movement of a pixel element of color pixelated SLM  16 C as it is projected onto the viewing surface  20 . For instance, first pixel element  60  would be displayed at a first pixel location at first position  70  on the viewing surface  20  during one portion of an image frame period. For a frame period of 1/60 th  of a second, the first position  70  would be occupied by first pixel element  60  for about 1/240 th  of a second. During the next portion of the image frame period, the first pixel element  60  would be shifted by the wobulation control circuit  18  to occupy the second position  72  which is a second pixel location on the viewing surface  20 . This position would be held for about 1/240 th  of a second before the wobulation control circuit  18  shifts the first pixel element  60  to a third pixel location  74  on the viewing surface  20 . This position would be held for about 1/240 th  of a second before being shifted by the wobulation control circuit  18  to a forth pixel location  76 . This position would be held for about 1/240 th  of a second before being shifted by the wobulation control circuit  18  back to the first pixel location  70 . The intensity of the perceived pixel on the viewing surface can be controlled at each position by adjusting the amount of time that the first pixel element  60  is actually enabled while it occupies a particular pixel location on the viewing surface. For instance, the first pixel element  60  can be pulse width modulated to have a duty cycle of 75% to have ¾ th  of the full intensity while positioned at first position  70 . To have a color depth of 8 bits, the first pixel element  60  would need to be controllable to have an off/on state of 1/256 th  of 1/240 th  of a second or 1/61,440 th  of a second (about 16 microseconds) for a 60 fps video.  
         [0047]      FIG. 10  is an exemplary timing diagram showing the timing of a respective perceived pixel on the viewing surface  20  during a single image frame period. During the first sub-period  80 , the perceived pixel location has a blue pixel such as first pixel  60  projected onto the pixel location. The first pixel  60  can be modulated appropriately during this sub-period  80  to achieve a desired intensity. During the second sub-period  82 , the second pixel element  62 , a red pixel is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. Again, during this sub-period  82 , the second pixel element  62  can be appropriately modulated to provide a desired red intensity level. During the third sub-period  84 , third pixel element  66 , a white pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. The third pixel element  64  can be appropriately modulated to provide a desired white intensity level by turning the pixel on or off. Finally, during the fourth sub-period  86 , the fourth pixel element  66 , a green pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. The fourth pixel element  66  can be appropriately modulated to provide a desired green level by turning the pixel on or off. The wobulation control circuit  18  then shifts or adjusts the first pixel element onto the perceived pixel location on the viewing surface  20  for the next image frame period.  
         [0048]     Alternatively, in another embodiment, the color gamut can be increased by including more than three primary colors. For instance,  FIG. 11  is an exemplary diagram of a portion of a color pixel SLM  16 D in which the pixel elements  90 ,  92 , and  94  are spatially distributed in a color scheme that is laid out in a triangular fashion that repeats over the pixel array. In this example, first pixel element  90  defines a red pixel color primary, second pixel element  92  defines both yellow (Y) and green pixel color primaries, and third pixel element  94  defines both cyan (C) and blue pixel color primaries.  
         [0049]      FIG. 12  is an exemplary diagram of the movement of a pixel element as it is projected onto the viewing surface  20 . For instance, first pixel element  90  would be displayed at a first pixel location at first position  96  on the viewing surface  20  during one portion of an image frame period. For a frame period of 1/60 th  of a second, the first position  96  would be occupied by first pixel element  90  for about 1/180 th  of a second. During the next portion of the image frame period, the first pixel element  90  would be shifted by the wobulation control circuit  18  to occupy the second position  97  which is a second pixel location on the viewing surface  20 . This position would be held for about 1/180 th  of a second before the wobulation control circuit  18  shifts the first pixel element  90  to a third pixel location  98  on the viewing surface  20 . The position would be held for about 1/180 th  of a second before being shifted by the wobulation control circuit  18  back to the first position  96 . The intensity of the perceived pixel on the viewing surface can be controlled by adjusting the amount of time that the first pixel element  90  is actually enabled while it occupies a particular pixel location on the viewing surface. For instance, the first pixel element  90  can be pulse width modulated to have a duty cycle of 10% to have one-tenth full intensity while positioned at first position  96 . To have a color depth of 8 bits, the first pixel element  90  would need to be controllable to have an off/on state of 1/256 th  of 1/180 th  of a second or 1/46,080 th  of a second (about 21 microseconds) for a 60 fps video. For the second pixel element  92  and third pixel element  94 , since they each control two colors, they would need to operate at twice the speed of the first pixel element  96  or alternatively they could support smaller color depths.  
         [0050]      FIG. 13  is an exemplary timing diagram showing the timing of a respective perceived pixel on the viewing surface during a single image frame period. During the first sub-period  100 , the perceived pixel location has a red pixel such as first pixel  90  projected onto the pixel location. The first pixel  90  can be modulated appropriately during this sub-period  100  to achieve a desired intensity. During the second sub-period  101 , the second pixel element  92  is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. Again, during this sub-period  101 , the second pixel element  24  can be appropriately modulated to provide a desired yellow intensity level before spectrally and intensity modulating the light during the third sub-period  102  to create green light. During the fourth sub-period  103 , third pixel element  94  is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. The third pixel element  94  can be appropriately modulated to provide a desired cyan intensity before spectrally and intensity modulating the light during the fifth sub-period  104  to create blue light.  
         [0051]     In addition to color wobulation, the wobulation control circuit  16  can be used to also increase the perceived resolution of the perceived image on the viewing surface  20  by shifting or otherwise positioning the pixel elements on the pixel locations of the viewing surface  20  by moving the pixel elements location on the viewing surface  20  as illustrated in  FIG. 15 . Thus, both color and image resolution wobulation can be achieved with embodiments of this invention by allowing for non-integer shifts by the wobulation control circuit  18 .  
         [0052]      FIG. 14  is a partial view of an array of pixel elements in a color pixelated SLM  16 E which has at least one white pixel element along with the primary color elements such as shown in  FIG. 8 . For instance, color pixelated SLM  16 E has a first pixel element  60  which is capable of generating a black (K) or blue color, a second pixel element  62  which is capable of generating a black or red color, a third pixel element  66  which is capable of generating a black or white (such as unfiltered) light, and a fourth pixel element  64  which is capable of generating a black or green color.  
         [0053]      FIG. 15  is an exemplary diagram of the movement of a pixel element of color pixelated SLM  16 E as it is projected onto the viewing surface  20 . For instance, first pixel element  60  would be displayed at a first pixel location at first position  120  on the viewing surface  20  during one portion of an image frame period. For a frame period of 1/60 th  of a second, the first position  120  would be occupied by first pixel element  60  for about 1/480 th  of a second. During the next portion of the image frame period, the first pixel element  60  would be shifted by the wobulation control circuit  18  to occupy the second position  122  which is a second pixel location on the viewing surface  20 . This position would be held for about 1/480 th  of a second before the wobulation control circuit  18  shifts the first pixel element  60  to a third pixel location  124  on the viewing surface  20 . This position would be held for about 1/480 th  of a second before being shifted by the wobulation control circuit  18  to a fourth pixel location  126 . This position would be held for about 1/480 th  of a second before being shifted by the wobulation control circuit  18  to the fifth pixel location  128 . This position would be held for about 1/480 th  of a second before the wobulation control circuit  18  shifts the first pixel element  60  to a sixth pixel location  130  on the viewing surface  20 . This position would be held for about 1/480 th  of a second before being shifted by the wobulation control circuit  18  to a seventh pixel location  132 . This position would be held for about 1/480 th  of a second before being shifted by the wobulation control circuit  18  to the eighth pixel location  134  which would also be held for 1/480 th  of a second before being shifted back to the first position  120 . The intensity of the perceived pixel on the viewing surface can be controlled at each position by adjusting the amount of time that the first pixel element  60  is actually enabled while it occupies a particular pixel location on the viewing surface. For instance, the first pixel element  60  can be pulse width modulated to have a duty cycle of 75% to have ¾ th  of the full intensity while positioned at first position  120 . To have a color depth of 8 bits, the first pixel element  60  would need to be controllable to have an off/on state of 1/256 th  of 1/480 th  of a second or 1/120,880 th  of a second (about 8 microseconds) for a 60 fps video.  
         [0054]      FIG. 16  is an exemplary timing diagram showing the respective timings of a respective perceived pixel at a first location on the viewing surface  20  during a single image frame period and a second (adjacent) offset pixel location on the viewing surface  20 . During the first sub-period  140 , the first pixel location has a red pixel such as second pixel  62  projected onto the pixel location. The second pixel  62  can be modulated appropriately during this sub-period  140  to achieve a desired intensity. During the second sub-period  142 , the first pixel element  60 , a blue pixel is positioned or otherwise shifted by the wobulation control circuit  18  onto the first perceived pixel location on the viewing surface. Again, during this sub-period  142 , the first pixel element  60  can be appropriately modulated to provide a desired blue intensity level. During the third sub-period  144 , the first pixel element  62 , a blue pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the offset pixel location on the viewing surface. The first pixel element  62  can be appropriately modulated to provide a desired blue intensity level by turning the pixel on or off. During the fourth sub-period  1466 , the fourth pixel element  66 , a green pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the first pixel location on the viewing surface. The fourth pixel element  66  can be appropriately modulated to provide a desired green level by turning the pixel on or off. The wobulation control circuit  18  then shifts or adjusts the fourth pixel element  66  onto the offset pixel location on the viewing surface  20  for the fifth image frame period  150 . Again, during this sub-period  150 , the fourth pixel element  66  can be appropriately modulated to provide a desired green intensity level. During the sixth sub-period  152 , the third pixel element  64 , a white pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the offset pixel location on the viewing surface. The third pixel element  64  can be appropriately modulated to provide a desired white intensity level by turning the pixel on or off. During the seventh sub-period  154 , the third pixel element  64 , a white pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the first pixel location on the viewing surface. The third pixel element  64  can be appropriately modulated to provide a desired white level by turning the pixel on or off. The wobulation control circuit  18  then shifts or adjusts the second pixel element  62  onto the offset pixel location on the viewing surface  20  for the eighth image frame period  156 . The second pixel element  62  can be appropriately modulated to provide a desired red intensity level by turning the pixel on or off. During the next frame period&#39;s first sub-period  140 , the second pixel element  62 , a red pixel, is positioned or otherwise shifted by the wobulation control circuit  18  back onto the first pixel location on the viewing surface.  
         [0055]     While earlier examples have shown the modulator pixel color patterns and the wobulation shift sequence patterns as being similar, it is possible to have the modulator pixels distributed in a rectangular pattern and the wobulation shift sequence triangular. This combination would still allow for full areal coverage of the pixel colors.  FIGS. 17-19  illustrate such an embodiment.  
         [0056]      FIG. 17  is an exemplary diagram of a portion of a color pixel SLM  16 F in which the pixel elements  160 ,  162 , and  164  are spatially distributed in a color scheme that is laid out in a rectangular fashion that repeats over the pixel array. In this example, first pixel element  160  defines a red pixel color primary, second pixel element  162  defines a green pixel color primary, and third pixel element  164  defines a blue pixel color primary.  
         [0057]     Absent a wobulation device  18 , the color pixel SLM  16 F produces a pixel pattern on the screen approximately matching the pattern depicted in  FIG. 17 . As is seen, each primary color is depleted to about one third of full areal coverage  
         [0058]      FIG. 18  is an exemplary diagram of the movement of a pixel element as it is projected onto the viewing surface  20 . For instance, first pixel element  160  would be displayed at a first pixel location at first position  166  on the viewing surface  20  during one portion of an image frame period. For a frame period of 1/60 of a second, the first position  166  would be occupied by first pixel element  160  for approximately 1/180 th  of a second. During the next portion of the image frame period, the first pixel element  160  would be shifted by the wobulation control circuit  18  to occupy the second position  168  which is a second pixel location on the viewing surface  20 . This position would be held for about 1/180 th  of a second before the wobulation control circuit  18  shifts the first pixel element  160  to a third pixel location  170  on the viewing surface  20 . The position would be held for 1/180 th  of a second before being shifted by the wobulation control circuit  18  back to the first position  166 . The intensity of the perceived pixel on the viewing surface can be controlled by adjusting the amount of time that the first pixel element  160  is actually enabled or activated while it occupies a particular pixel location on the viewing surface. For instance, the first pixel element  160  can be pulse width modulated to have a duty cycle of 50% to have one half of the full intensity while positioned at first position  166 . To have a color depth of 8 bits, the first pixel element  160  would need to be controllable to have an off/on state of 1/256 th  of 1/180 th  of a second or 1/46,080 th  of a second (about 21 microseconds) for a 60 frames per second (fps) video.  
         [0059]     By utilizing the displacement of the pixel elements as depicted and discussed with respect to  FIG. 18 , essentially full area coverage of the viewing area is provided for each primary color. Stated another way, each of pixel elements  160 ,  162 , and  164  that display red, green, and blue respectively, can address multiple pixel locations on the viewing screen to reduce or eliminate primary color depletion.  
         [0060]      FIG. 19  is an exemplary timing diagram showing the timing of a respective perceived pixel on the viewing surface to generate a full-on white pixel during a single image frame period. The modulator pixels can of course be modulated between the stated color and black to create a perceived pixel of many possible colors. During the first sub-period  172 , the perceived pixel location has a red pixel such as first pixel  160  projected onto the pixel location. The first pixel  160  can be modulated appropriately during this sub-period  172  to achieve a desired intensity. During the second sub-period  174 , the second pixel element  162 , a green pixel is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. Again, during this sub-period  174 , the second pixel element  162  can be appropriately modulated to provide a desired green intensity level. During the third sub-period  176 , third pixel element  164 , a blue pixel, is positioned or otherwise shifted by the wobulation control circuit  18  onto the perceived pixel location on the viewing surface. The third pixel element  164  can be appropriately modulated to provide a desired blue intensity level by turning the color on or off (that is, off being a black state).  
         [0061]     By utilizing the displacement of the pixel array, locations on the viewing surface may be more completely addressed with all three primary colors while still employing a rectangular arrayed pattern. This eliminates a tendency of a particular single perceived pixel location to only be able to display red or black for instance. In the example discussed with respect to  FIG. 18 , a white pixel is perceived when all three primary colors are properly enabled in sequence for a particular pixel location.  
         [0062]     While the present invention has been particularly shown and described with reference to the foregoing preferred and alternative embodiments, those skilled in the art will understand that many variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Where the claims recite “a” or “a first” element of the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.