Abstract:
A flat panel display uses pixels ( 2060 ) that are turned on or off by the enabling or disabling total internal reflection, TIR, of a light guide ( 2010 ). A reflective surface ( 2070 ) directs the switched light towards the viewer. An optional mask may be employed to provide extremely high contrast ratios in low and in high ambient lighting conditions. The elements ( 2080 ) that enable TIR may be enabled quickly because of their small size and weight, resulting in a very fast switching speed. The fast switching speed allows colors to be generated and displayed in a sequential manner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of and claims the priority benefit of U.S. patent application Ser. No. 12/319,171, filed Jan. 2, 2009 now U.S. Pat. No. 8,152,352, entitled “TIR Switched Flat Panel Display” and is a continuation-in-part of and claims the priority benefit of U.S. patent application Ser. No. 12/319,172, filed Jan. 2, 2009 now U.S. Pat. No. 8,272,770, entitled “Optic System for Light Guide With Controlled Output,” each of which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to light display devices, and more particularly is a flat panel display in which the light is switched by enabling and disabling total internal reflection (TIR), and in which the switched light is directed by optics. 
     BACKGROUND OF THE INVENTION 
     Many products require flat panel displays to display video, computer or other data. Liquid crystal displays, LCDs, have become the dominant technology utilized in flat panel displays. Another, less common technology used for flat panel displays is plasma technology. Other known display technologies used in thicker flat panel displays are of the rear projection type. For very large displays, discrete arrays of LEDs are the dominant technology. These display technologies are used in many types of products including cellular phones, laptop computers, computer monitors, TVs, large commercial displays, and billboards. CRT type displays that used to be the dominant technology have almost vanished, even though the performance of the newer technologies is not significantly greater than CRT. Some current art LCD displays still cannot match the refresh rate of CRTs. 
     Displays based on LCD technology have been evolving for decades. Thousands of patents have been filed on improvements to the basic technology. Still, the performance of these displays lacks in many ways. 
     A first shortcoming of LCD display technology is the high energy consumption. A 65″ diagonal HDTV LCD TV typically draws around a half of a kilowatt. This is a result of the poor efficiency of the technology. LCDs need polarized light to function. However, approximately half of the light generated by the backlight is absorbed in the creation of polarized light. Many inventions have been devised to reduce this loss. In reality, little real improvement has been realized by manufactures due to cost or the reduction in other performance parameters. One product that is designed to recycle light not having the correct polarization is called ADBEF″ and is manufactured by 3M of Minneapolis, Minn. 
     Another factor that contributes to the low efficiency of LCD displays is the fact that pixels that are turned off absorb light rather than reflect it to another pixel that is on. 
     Another shortcoming of LCD displays is their limitations when used with color filters. Typically red, green, and blue filters are used to create colors. These filters do not reflect unused light, but rather absorb it. For example: red filters absorb the green and blue light while only letting red light pass through. In theory, a perfect blue filter would let 33% of the light through. In reality filter materials perform significantly less than the theoretical 33%. Another place where light is absorbed is in the matrix between the color filters. This matrix area is required for circuitry and transistors used to control the pixels. The required area is significant in that one pixel requires three transistors, one transistor being required for each of the three colors. Also, additional circuitry is required to drive the transistors. The matrix area between the filters may absorb approximately half the overall light available. When all of these and other losses such as reflection and material absorption are taken into consideration, an LCD panel may only be 8% efficient when all of the pixels are on. Typically an image has approximately one half of the pixels turned on when creating an image, and with the half of the pixels that are off absorbing rather than reflecting, the resulting LCD efficiency is only in the 4% range. 
     This poor efficiency requires the backlights used with LCD displays to be large and powerful. The dominant lamp technology used in displays is fluorescent type lamps. These lamps are reasonably efficient but require mercury. The mercury creates a disposal problem. In many cases, the mercury ends up in our food chain. 
     Another deficiency with LCD technology is the refresh rate. Only in the very recent past have LCDs been able to equal the refresh rate of CRT displays. For demanding applications such as the viewing of moving videos, the slow refresh rate of LCDs is apparent. Other problems with LCDs are poor contrast ratios. The contrast problem is exacerbated when viewed from a position off normal to the display surface. 
     The quality of the colors from an LCD display is limited by the wavelengths of light emitted from the light source and the properties of the color filters used in the display. Both of these factors result in displays that cannot accurately reproduce colors found in nature. 
     Another deficiency with LCD technology is its limited environmental operating range. The liquid crystal material doesn&#39;t function well at high and low temperatures. Displays that are used in extreme environments are often cooled or heated to keep them within a moderate operating range. Another problem with using LCDs in non-optimal environments is that the polarizing films required for LCD displays degrade when exposed to high humidity. Measures must be taken to reduce the effect of this property. In displays that are used in extreme environments the displays and their polarizing films are encased in glass windows. 
     Plasma thin panel display technology is the typical technology of choice for large screen TVs. The plasma displays also consume a significant amount of power. Plasma TVs do not last as long as LCD TVs and experience “burn in”. Burn in occurs when the on pixels remain on for a long period of time. These pixels lose their strength and become washed out over time. Cost is another issue with plasma technology. 
     In TV applications the projector is often deployed in a rear projection configuration. For computer monitors using projection display, the front projection mode is more commonly used. 
     Most rear and front projection displays utilize a MEMS mirror array. A MEMS mirror array is disclosed in each of U.S. Pat. Nos. 4,566,935; 4,596,992; 4,615,595; 4,662,746; 4,710,732; 4,956,619; and 5,028,939; all by inventor Larry Hornbeck of Texas, and assigned to Texas Instruments (TI) of Texas. The TI technology uses an array of MEMS mirrors that change their incidence angle to the light path to switch the light from an off position to an on position. When the mirror is in the on position, the mirror reflects the light through the optical path. When the mirror is in the off position, the light is reflected to a path that falls outside the projection optics. This in effect turns the light valve to an off state. 
     There are many deficiencies with this technology. One is that the light transmission is less than 70%. To allow for the change of angular orientation of the mirrors, there must be a substantial space between adjacent mirrors. The required gap causes a lot of light to be wasted. Further, the reflected light is absorbed into the light valve. The absorbed energy makes cooling the switching devices that use this technology a challenge. 
     Another flat panel display technology is disclosed in U.S. Pat. No. 5,319,491 by inventor Martin Selbrede of Thousand Oaks, Calif. This patent discloses a method in which the shape of an elastic membrane is changed to allow light to escape from a light guide. It is difficult to control the shape of the elastomer and therefore difficult to control the light output from the pixel. Light output from the pixels is dependent on the angle at which the light strikes the membrane. Also the angle at which the light exits the panel is off from normal. Typically light normal to the screen is the orientation in which you want the most output. Contrast ratio is limited with the elastic membrane technology. This limitation is due to the fact that any flaw in the light or optics lets light escape. An extremely small defect can produce enough light leakage to result in poor contrast when the display is primarily black. In high ambient lighting conditions the contrast is reduced by another factor. This factor is that the deformed elastomer will reflect, in some instances, the ambient light to the viewer. 
     Another flat panel display technology is disclosed in U.S. Pat. Nos. 6,040,937; 6,674,562; 6,867,896; and 7,124,216 all by inventor Mark Miles of Boston, Mass. This invention controls the distance between optical elements to control the interference characteristics of the pixel. This technology is only effective in a reflective mode and is therefore not applicable to most display applications. Three optical switches are required to create red, green, and blue colors. Not only are three-color optical switches required, but also the electronics to drive the switches must also be included. 
     Another display invention was recently disclosed in U.S. Publications 20050248827, and 20060070379, both by inventor Gary Starkweather of WA and assigned to Microsoft, also of WA. This technology is similar to the Hornbrook technology in that it switches light by bending or moving mirrors. This technology suffers due to its high complexity and therefore high cost. The advantage of this technology is that its theoretical efficiency is better than most other technologies. But in practice, the technology requires a collimated backlight source. Sources of this type are inefficient and costly. The cost of a display with this technology will be high and the efficiency still poor. Further, the creation of a collimated backlight source requires that there be considerable depth to the display. This depth is not desirable to consumers and therefore reduces the market for this technology. 
     The current invention utilizes micro-optical components. Some of the prior art related to this field should also be discussed. U.S. Pat. No. 6,421,103, by Akira Yamaguchi of Japan and assigned to Fuji Film, discloses a backlight for use with LCD panels. This patent discloses light sources, a substrate, apertures (not used as a light guide), and reflective regions on the substrate. The light is either reflected by the reflective surface or passes through the apertures. The light that passes through the apertures is captured by a lens and is used to control the direction of the light. The Yamaguchi reference teaches a restricted angle of the light to concentrate more light directly at the viewer of an LCD type display. 
     U.S. Pat. No. 5,396,350, by Karl Beeson of Princeton, N.J., discloses a light guide with optical elements that are used to extract light from the light guide. The optical elements are on the viewer&#39;s side of the panel and have limited ability to control the direction of the light. This invention is intended to be used in conjunction with an LCD type panel to concentrate light towards the viewer. 
     SUMMARY OF THE INVENTION 
     The present invention is a light valve for use in thin flat panel displays. Flat panel displays are used in cellular phones, laptop computers, computer monitors, TVs, and commercial displays. The light valve of the present invention either extracts light or allows light to travel up a light guide through the TIR process. 
     Light is initially injected into the light guide from the edges of the light guide. Light then travels up the light guide by reflecting off of the inside surfaces of the light guide. If the light reaches the top of the light guide, reflective material reflects the light back toward the bottom of the light guide. 
     As light travels up and down the light guide, the light will typically find a point where an element of the TIR switch is in an on position, in contact with the light guide. When a switch element contacts the light guide, light is extracted from the light guide and is directed to an optic system that redirects the light to the viewer. Switch elements that are not in contact with the surface of the light guide do not extract light. Contacting switches create an “on” pixel, while a switch not in contact with the light guide will create an “off” pixel. 
     Additional optics and masks can be added to a given system to improve contrast ratios, viewing angle, and other parameters that are important to the display viewer. By switching the pixels in sequence with alternating colors of light, a full color display can be created with a minimal number of switches. When a full gamut of colors is fed into the light guide, sequenced switching allows the colors to be presented to the viewer without filtering. 
     An advantage of the present invention is that it enables a flat panel display with far greater resolution than current art devices. 
     Another advantage of the present invention is that the technology is easily manufactured in a flat panel display. 
     A still further advantage of the present invention is that the device switches much faster than the prior art as it requires a very small movement of the optics to accomplish the switching. 
     Yet another advantage of the present invention is that it provides better color replication with a higher contrast ratio. 
     Still another advantage of the present invention is that the display functions well in non-ideal environments. 
     These and other objectives and advantages of the present invention will become apparent to those skilled in the art in view of the description of the best presently known mode of carrying out the invention as described herein and as illustrated in the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of the thin flat panel display with TIR switching technology. 
         FIG. 2  is an exploded view of the display shown in  FIG. 1 . 
         FIG. 3  is a magnified section of the lower left corner of the display shown in  FIG. 1 , with the display being rotated from a vertical orientation to horizontal. 
         FIG. 4  is a top perspective view of the electronics back plane component of the TIR display. 
         FIG. 5  is a bottom perspective view of the back plane component shown in  FIG. 4 . 
         FIG. 6  is a detail view of the film component of the TIR display shown in  FIG. 3 . 
         FIG. 7  shows the film component assembled with the electronics back plane component. 
         FIG. 8  is a magnified side view of the film component spaced away from the electronics back plane component. 
         FIG. 9  is a side view of the flat panel display. Some of the components of the display are not shown for clarity. 
         FIG. 10  is a side view of the display with several ray traces included. 
         FIG. 11  is a side view of the display with several ray traces included and the TIR light valves turned off. 
         FIG. 12  is a compressed broken section view of the light guide, LED, and light guide reflectors. 
         FIG. 13  is a side view of the flat panel display with all of the display components illustrated. 
         FIG. 14  is a perspective view of a small section of the black mask. 
         FIG. 15  is a magnified side view of the TIR switch film component and the electronics back plane assembled together. 
         FIG. 16  is a schematic diagram of the control electronics required for color sequencing. 
         FIG. 17  illustrates the flat panel display utilizing a piezo or electroelastomer element. 
         FIG. 18  shows the flat panel display with a fixed reflector. 
         FIG. 19  shows the flat panel display with a hollow fixed reflector. 
         FIG. 20  shows an embodiment of the technology. 
         FIG. 21  shows an embodiment of the technology. 
         FIG. 22A  illustrates an open window. 
         FIG. 22B  illustrates a closed window. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to  FIG. 1 , the TIR switched thin flat panel display  1  of the present invention comprises a panel area  2 . The panel area  2  has green LEDs  3 , blue LEDs  4 , and red LEDs  5  located along a lower edge. The number of LEDs  3 ,  4 ,  5  and the side where they are located is a function of the size, shape, and application of the desired display. The LEDs  3 ,  4 ,  5  could be located on more than one edge should a specific application require it. The LEDs  3 ,  4 ,  5  require driver electronics to drive them at the proper level and at the proper timing. A person skilled in the art of LED driver electronics could devise many different circuits to accomplish this task. In the embodiment illustrated in  FIG. 1 ,  27  LEDs  3 ,  4 ,  5  are shown generally equally spaced along the bottom edge. With the high efficiency inherent in the TIR technology, a display with this large number of LEDs would be intended for outdoor use, with high ambient light. A display intended for a use in low ambient light would require fewer LEDs  3 ,  4 ,  5 . 
       FIG. 2  is an exploded view of the panel area  2 , which comprises four major components. A mask and diffusion assembly  6  forms a front layer of the panel area  2 . Behind the mask and diffusion assembly  6  is a light guide  7 . Behind the light guide  7  is a TIR switch film  8 . An electronics back plane  10  is situated behind the switch film  8 . All four of the major components  6 ,  7 ,  8 ,  10  have the same area as a pixel area  11 . The number of pixels required is dependent on the display resolution. 
     The four major components  6 ,  7 ,  8 ,  10 , shown exploded in  FIG. 2 , would in use be mated to one another as shown in  FIG. 1 . A cross section of a small corner of the mated assembly is shown enlarged in  FIG. 3 . 
     In  FIG. 3 , the green, blue, and red LEDs  3 ,  4 ,  5  are shown in their true relationship to the light guide  7 . An end reflective plate  9  covers the same edge of the light guide  7  as do the LEDs  3 ,  4 ,  5 . (Reflective plate  9  is shown in greater detail in  FIG. 12 , and its function will be discussed below.) The relative thicknesses of the major components  6 ,  7 ,  8 ,  10  can be seen in  FIG. 12 . The relative thicknesses of the major components  6 ,  7 ,  8 ,  10  would change for different sizes and pitches of a given display. 
     Referring now to  FIG. 4 , the electronics back plane  10  is shown in the same orientation as it is in  FIG. 3 . The substrate material for the electronics back plane  10  should be an insulating material. For larger displays, a fiberglass reinforced PCB material or the like is desirable as the substrate. For smaller displays, the insulating substrate material may be glass, silicon, or plastic. The substrate material does not need to be optically transparent, so there are many options for material selection. 
     Electronic components may be located on the planer surface  21  of the electronics back plane  10 . For clarity, none of those components are shown in  FIG. 4 . Annular rings  22  are located near the centerline of the pixel areas. The annular rings  22  may be made of a conductive material, and are generally thin. The annular ring pocket  23  is a recessed area for clearance from optical components (discussed below). The annular ring pockets  23  may also be made of conductive material and are thin. If any electronics were located on the backside of the electronics back plane  10  at least one feed through hole  24  would be required. The feed through holes  24  are shown to be concentric to the annular ring  22 , but concentricity is not required. The feed through holes  24  could be located anywhere on the electronics back plane  10 . The feed through holes  24  have a thin layer of conductive material that connects the annular rings  22  to any electronics present on the backside of the electronics plane  10 . It should be noted that any electronic components such as transistors, capacitors, or resistors that are required for the subject display application could be located either between the annular rings  22  or beneath the surface of the electronics back plane  10 . 
     Referring now to  FIG. 5 , the feed through holes  24  are visible on the back side of the electronics back plane  10 . Bottom side annular rings  25  are formed from a thin layer of conductive material to provide electrical conductivity with the feed through holes  24 . Conductive traces  26  are used to connect the bottom side annular rings  25  to circuitry located elsewhere on the backside of the board. Alternatively, the annular rings  25  can be connected to an electrical connector, which would put the annular rings  25  in communication with other electronic components on a remote PCB. One skilled in the art of electronic layout and manufacturing could easily define the appropriate location and type of electronics to reduce the overall system cost while improving performance. 
     The TIR switch film  8  is shown in  FIG. 6 . The TIR switch film  8  is made of a transparent flexible type material such as polycarbonate, polyester, acrylic, or the like. The top surface  31  of the TIR switch film  8  is situated in close proximity to the surface of the light guide  7  (not shown in  FIG. 6 ), but there is a narrow gap between the top surface  31  of the switch film  8  and the surface of the light guide  7 . The contact domes  32  are ideally located in the center of the pixel area. (The contact domes  32  can be seen in more detail in  FIG. 8 .) The contact domes  32  preferably have a shallow taper and a flat region on a top surface. The flat region may be shaped to mate with (i.e. match to) a corresponding portion of the light guide. For very short contact domes  32 , the domes  32  may not have any taper at all. (A contact dome without taper has the advantage of being able to be formed with a lithographic process. A dome with tapered sides would be best formed with a molding process.) Each of the contact domes  32  includes a reflector perimeter  33 . The reflector perimeter  33  is positioned on the back side of the switch film  8 , but is visible in  FIG. 6  because the TIR switch film  8  is transparent. The TIR switch film  8  is very thin to enable it to flex easily. The thickness of the switch film  8  is less than 1/10 the diameter of the reflector perimeter  33 . 
     Spacer posts  34  comprise another main element of the TIR switch film  8 . The spacer posts  34  are located between the contact domes  32 . The spacer posts  34  maintain the narrow gap  60  (visible in  FIG. 15 ) between the switch film  8  and the light guide  7 . The spacer posts  34  are illustrated in  FIGS. 6-8  as being square, but other shapes could be used as well. The spacer posts  34  extend downward through the switch film  8  and out the bottom side to form the bottom spacer posts  34 ′. The bottom spacer posts  34 ′ can most easily be seen in  FIG. 8 . 
       FIG. 7  shows the TIR switch film  8  assembled to the electronics back plane  10 . The annular rings  22  on the electronics back plane  10  can be seen through the transparent TIR switch film  8 . The centerline of the pixel features of the TIR switch film  8  and the electronics back plane  10  are generally in alignment. 
       FIG. 8  shows an exploded sectional side view of the electronics back plane  10  and the TIR switch film  8 . The annular ring pockets  23  are shown in  FIG. 8  as spherical in shape. The shape of the annular ring pockets  23  could be rectangular, trapezoidal or an irregular shape. The shape of the ring pockets  23  has no effect on the optical function of the invention. Reflectors  35  are received in the ring pockets  23 . The shape of the reflector  35  is depicted as generally spherical, a reflector shape that would be acceptable for many applications. However, in most display applications the ideal shape for the reflectors  35  would be aspheric. The specific optimal aspheric shape of the reflectors  35  is a function of dome diameter, dome taper, dome position relative to the aspheric reflector, the index of refraction of the various components, and the diameter of the reflectors  35 . Additionally, manufacturing methods for the reflectors  35  may have a practical effect on the shape chosen for the reflectors  35 . One skilled in the art of the design of reflectors could devise a reflector shape to meet the specific design goals of a given overall display. 
     The bottom spacer posts  34 ′ are formed from the lower end of the spacer posts  34 . The bottom surface of the bottom spacer posts  34 ′ is in contact with and bonded to the planer surface  21  of the electronics back plane  10 . The top surface of the spacer post  34  is bonded to the light guide  7 . The adhesive for this bond should have a low index of refraction. If the adhesive has too high an index, the mating surface of the light guide  7  would need to be coated with a low index material.  FIG. 9  shows the TIR switch film  8  bonded to the light guide  7 . The contact domes  32  are in contact with the light guide  7 . In those cases in which the light guide  7  is coated with a low index material, the areas where the contact domes  32  make contact with the light guide  7  must be void of the low index material. 
     Referring next to  FIG. 10 , light rays  41  originate from the green LED  3 . The light rays  41  reflect off the film side surface  42  of the light guide  7 . This reflection of the light rays  41  is total internal reflection, TIR. TIR occurs when the angle from normal to the film side surface  42  to the direction of the ray, angle  A A@, is less than the arcsine of the quotient of the index of refraction of the material adjacent to the surface of the light guide,  A Ns@, to the index of refraction of the material of the light guide,  A Nlg″. For the case where the light guide is made from acrylic and the adjacent material is air, angle A would be:
 
Angle  A =arcsine(1/1.5)=41.8° for  Ns= 1 and  Nlg= 1.5
 
If the internal angle A is less than 41.8 degrees, light reflects off of the internal surface. If the angle A is greater than 41.8 degrees, the light passes through the surface and is refracted to a different angle.
 
     There are three cases where different materials are adjacent one another, and angle A is different for all three, they are: 
     Case 1 is when the light guide (index 1.5) is adjacent to air (index 1) 
     Case 2 is when the light guide (index 1.5) is adjacent a contact dome (index 1.5) 
     Case 3 is when the light guide (index 1.5) is adjacent a low index material (index 1.35) 
     Calculating the angle A for these three cases: 
     A=arcsine (Ns/Nlg)
         Case 1 For Ns=1, Nlg=1.50 A=arcsine (1/1.50)=41.8 degrees   Case 2 For Ns=1.50, Nlg=1.50 A=arcsine (1.50/1.50)=90 degrees   Case 3 For Ns=1.35, Nlg=1.50 A=arcsine (1.35/1.50)=64.2 degrees       

     From these three calculations it can be seen that light will continue to reflect down the light guide  7  when the approach angle of the light rays  41  is less than 62.5 degrees from normal to the surface of the light guide  7 . Case 1 and case 3 are conditions where light would TIR. In case 2, the light does not TIR. The light passes through the surface of the light guide  7  and continues along its original path through the contact dome  32 . 
     It should be noted that the light guide  7  and the contact dome  32  may not have the same index of refraction. If the indexes of refraction are not equal, some refraction will take place at the interface of the light guide  7  and the contact dome  32 . The difference in the index of refraction between the materials determines the amount of the refraction. Preferably the index of refraction of the contact dome  32  is greater than that of the light guide  7 . If the index of refraction of the contact dome  32  is less than that of the light guide  7 , some of the light that is traveling at large angles normal to the surface of the light guide  7  would TIR and not pass through to the contact dome  32 . 
     To correlate the three classes of angle A to  FIG. 10 : The reflection off the film side surface  42  using the air index of refraction is the first TIR reflection of light ray  41 . This reflection would be bound by the equation of case 1. The low index TIR reflection  44  is a TIR reflection of the second light ray  43 , and is bound by the equation of case 3. The third internal light ray  45  strikes the matched index point  46  and does not experience TIR. Light rays  45  pass through the light guide  7  and contact dome  32  materials without a reflection, assuming that when light rays  45  impinge on this point, the contact dome  32  is in contact with the light guide  7 . It should be noted that the junction must be void of gaps. Even a small air gap would disrupt the passing of light. A small gap can be created by a small variation in surface finish or even by a small foreign particle. Addition of a thin layer of transparent elastic material on either the surface of the light guide  7  or the surface of the contact domes  32  ensures that the disruptions will not occur and the light will pass as desired. 
     The light rays  45  continue beyond the contact dome  32  and reflect off of the surface of the reflector  35 . The reflector  35  is preferably coated with a high reflectance material such as aluminum, silver, or a dielectric coating. The contour of the reflector  35  surface determines the direction of the reflected light  48 . As discussed above, the contoured reflectors  35  are preferably aspheric in shape. 
       FIG. 11  shows the same elements as are shown in  FIG. 10 , but in  FIG. 11  the contact dome  32  is not in contact with the light guide  7 . When the contact dome  32  is not in contact with the surface of the light guide  7 , the index of refraction at the surface of the light guide  7  is that of air. Under these conditions, case 1, light TIRs off the surface of the light guide  7 . Light rays  49  continue to TIR along the inside of the light guide  7  until the rays  49  impinge on a contact dome  32  that is in contact with the light guide  7 . In summary, when a contact dome  32  associated with a particular pixel is in contact with the surface of the light guide  7 , that pixel is in an on state. When the contact dome  32  is not in contact with the light guide  7 , the pixel is off. 
       FIG. 12  shows the light guide  7 , LED  3 , and the end reflectors  9  and  9 ′ in side magnified view. End reflectors  9 ,  9 ′ are preferably formed from a material that has a high reflectance. End reflectors  9 ,  9 ′ can be interference type or metal reflectors, or the reflectors  9 ,  9 ′ could be angled retro type reflectors. 
     Light will often travel the length of the light guide  7  from the LED  3  and not strike a contact dome  32  that is in the on position. The light will therefore TIR and will not be extracted from the light guide  7 . In this case the light continues to travel along the full length of the light guide  7  until the light reaches the distal end of the light guide  7 , and is reflected off end reflector  9 =. This reflection redirects the light in the opposite direction back through the light guide  7 . The light then travels back along the length of the light guide  7 , and assuming it strikes no activated contact domes  32 , will return to the first end of the light guide  7 , the end on which the LEDs  3 , 4 , 5  are located. 
     At the first end, the light will either strike the area between the LEDs  3 , 4 , 5  or it will strike the LEDs  3 , 4 , 5 . When the light strikes the area between the LEDs  3 , 4 , 5 , it will be reflected by the end reflector  9 . If the TIR flat panel display  1  has only a few LEDs  3 , 4 , 5 , the light will almost always reflect off of the high reflectance end reflector  9 . In some cases the light will reflect off of an LED  3 , 4 , 5 . The LED  3 , 4 , 5  will absorb a portion of the light, and the remainder of the light will be reflected. Light may travel up and down the light guide  7  a number of times before it is extracted by a contact dome  32 . This would be the case when only a few contact domes  32  are on and extracting light. If many of the contact domes  32  were on and in contact with the light guide  7 , the likelihood of light making more than one or two passes along the light guide  7  is small. Even if there are a large number of reflections and the light makes multiple passes along the light guide  7 , the loss of light is small. The end reflectors  9 ,  9 ′ may have reflectance efficiencies of 98% or better, and good quality light guide material absorbs very little light. 
     Referring now to  FIG. 13 , a mask and diffusion assembly  6  is mounted above the panel area  2 . The mask and diffusion assembly  6  is a multi-layered assembly, comprising a low index layer  51 , a spacer plate  52 , a mask plate  53 , a first diffuser  55 , a second spacer  56 , and a second diffuser  57 . 
     The low index layer  51  is thin and has a low index of refraction. An air gap or a vacuum layer could serve as the low index layer  51 , but forming the low index layer  51  from a low refraction index solid material is often beneficial to the assembly of the device. The low index layer  51  will typically be an adhesive that affixes the spacer plate  52  to the light guide  7 . In applications that require extremely thin displays, the low index layer  51  and the spacer plate  52  can be combined into one element, a thicker low index layer  51 . However, for larger displays, the use of two different materials to form the low index layer  51  and the spacer plate  52  is more beneficial. 
     Two thin layers, the mask plate  53  and the first diffuser  55 , are positioned between the spacer plate  52  and the second spacer  56 . The mask plate  53  contains multiple aperture holes  54  (see  FIG. 15 ) to allow the reflected light  48  to pass through the mask plate  53 . The remaining area of the mask plate  53  is preferably high absorbing black material. Black chrome, carbon black, or an organic material are three types of material that would serve as suitable materials for the mask plate  53 . The mask plate  53  increases the contrast ratio of the display when ambient light is present. The mask plate  53  absorbs light that would otherwise reflect from the TIR switch film  8  or any of its components. For inexpensive displays, where cost is more important than quality, the mask plate  53  can be eliminated. Also, the mask plate  53  may be eliminated where the display is only used in low ambient lighting conditions. An example of a low ambient light environment would be a motion picture cinema. 
     The first diffuser  55  is an optional diffuser to spread the light coming from the reflectors  35 . For small displays the first diffuser  55  may not be required, but for displays with large pixels, the first diffuser  55  should be included. It should also be noted that the positions of the mask  53  and the first diffuser  55  could be reversed without affecting the function of the display. 
     The second spacer  56  allows the light transmitted from the reflectors  35  to begin to spread out. The second diffuser  57  is used to spread the light still further so that the viewer can be at a position far from normal to the display and still see the light from the reflectors  35 . The amount and direction of diffusion that is incorporated into the second diffuser  57  will vary for different types of displays. For example, small cell phone displays typically have a smaller viewing angle in both the vertical and horizontal directions. TVs typically have a large viewing angle in the horizontal direction and not as big a viewing angle in the vertical direction. 
     Referring now to  FIG. 15 , the TIR switch film  8  is assembled to the electronics back plane  10 . There is a small air gap  60  between the switch film  8  and the electronics back plane  10  maintained by the spacer posts  34 . The annular rings  22  of the electronics back plane  10  are in close proximity to the bottom surface  36  of the TIR switch film  8 . The bottom surface  36  is coated with a conductive layer  62 . For ease of fabrication, the conductive layer  62  may be a continuation of the surface of the reflector  35 . When the conductive layer  62  and the annular ring  22  are electrically charged, an electrostatic force is created. When the charges are of like polarity, the surfaces repel one another. When the charges are of opposite polarity, the surfaces are drawn to one another. Therefore, by controlling the relative charge of these surfaces, the conductive layer  62  and the annular ring  22 , the contact domes  32  can be driven against or removed from contact with the surface of the light guide  7  (not shown in  FIG. 15 ). To keep the two charged surfaces from shorting, either one or both of the charged surfaces is coated with an insulating layer. 
     It should be noted that electrostatic force is not the only means that can be used to control the contact of the contact domes  32  with the surface of the light guide  7 . One alternate method would be the use of a piezoelectric material. Another would be to use magnetism. Those skilled in the art of actuation devices could devise many ways to change the positions of the contact domes  32 . Further, there are a limitless number of electronic circuits that could be devised to drive the actuator. 
       FIG. 16  depicts schematic representations of the circuitry used to create colors at the pixels. To create a green image for the viewer at pixel n,m, the switch for pixel n,m is moved to a state that has the contact dome  32  in contact with the light guide  7 , and the driver for the green LED  3  is turned on. The blue and red LEDs  4 ,  5  would not be on. (One exception to this case is if the display was only creating a black and white image. Then all three LEDS  3 , 4 , 5  would be on at the same time. Alternatively, a white LED could be used.) The contact dome  32  associated with pixel n,m remains in contact with the light guide  7  for the appropriate period of time to allow the desired amount of light to exit the pixel to create to create the desired intensity for the viewer. To create a blue display, the contact dome  32  is placed in contact with the light guide  7  when the blue LED  4  is on. The contact dome  32  remains in contact the amount of time required to create the particular intensity needed for the viewer. Red colors are created in a similar manner. To create secondary colors or white, the contact dome  32  is placed in contact with the light guide for two or more periods when two or three of the LEDs  3 , 4 , 5  are on. 
     For example, to create a yellow image at a pixel, the contact dome  32  would extract light from the light guide  7  when the red LED  3  is on. After the red LED  3  goes off, the blue LED  4  is turned on. The contact dome  32  does not extract light during the time the blue LED  4  is on. The green LED  5  would be turned on after the blue LED  4  is turned off. When the green LED  5  is on, the contact dome  32  would again allow light to reach the viewer. This would happen hundreds of times per second resulting in the human eye integrating the red and green into yellow. The length of time that the contact dome  32  allows light to reach the viewer determines the brightness. By altering the individual time periods for the red and green the hue of the yellow can be controlled. Some blue light can be added to reduce the saturation of the yellow. 
     It should be noted that LEDs do not typically emit a wide range of wavelengths of light. A high quality display may include LEDs with wavelengths between the primary RGB LEDs. Examples are orange, cyan and yellow. By adding these extra wavelengths the spectrum output of the TIR display could be made to match what a viewer would see in the real world. Very little additional circuitry is required to add this improved performance. 
     It should also be noted that electronics are required to control the switches and the LEDs of the present invention. Electronics are also required to relate the operation of the optics elements to a computer, TV, or other type of video signal. Control electronics of this type are created for display systems that create colors by multiplexing the colors in time. One skilled in the art would be able to devise many ways to accomplish this task. The innovative part of this invention is the optical switching and optics, not the configuration of the electronic components. 
       FIG. 17  illustrates the device using a piezoelectric material  70  as the actuating mechanism. This embodiment shows the actuation material  70  attached to the reflector surface  35 . The piezoelectric material  70  is driven with the same type electronics back plane  10  as is used to drive the electrostatic force switching mechanism. By changing the height of the piezoelectric material  70 , the reflector surface  35 , and therefore the contact dome  32 , can be turned on and off. 
     Another configuration of the device is shown in  FIG. 18 , which shows the contact domes  32  mounted on angled cones  80  on the elastic switch film  8 . This configuration is preferred when the reflector size is large. The reflector would be stationary and would have an angled cone relieved area  82  slightly larger than the angled cone  80  mounted on the switch film  8 . The relieved area  82  allows clearance for the contact dome  32  and the angled cone  80  to move into contact with, and away from, the light guide  7 . 
       FIG. 19  illustrates a configuration of the device in which the reflector area  35 ′ is void of material and would be air or a vacuum. The reflector area  35 ′ would still be employed to reflect light. 
       FIG. 20  illustrates an embodiment. Light  2000  may be transmitted through light guide  2010 . Light guide  2010  may have a first index of refraction and may include one or more surfaces between light guide  2010  and another medium (e.g., a solid, liquid, air, or even vacuum) having a second index of refraction. Surfaces may be substantially planar, curved, elongated (e.g., having one dimension much greater than another dimension, such as ten times or even 100 times greater) and other shapes. Light guide  2010  may include a first surface  1020  configured to receive light from a light source (not shown), a second surface  2030  (e.g., from which light may exit light guide  2010 ), and a third surface  2040  associated with various light control apparatus such as a window into a contact dome. Light guide  2010  may include one or more fourth surfaces  2050 . In some cases, fourth surface  2050  may receive light from a light source. In some cases, fourth surface  2050  may be at least partially mirrored. In certain embodiments, fourth surface  2050  may include a fully reflecting mirror, which may reflect light incident on fourth surface  2050  from within light guide  2010  back into light guide  2010 . 
     Light guide  2010  may be characterized by one or more lengths, such as length  2012  and thickness  2014 . Lengths may be chosen according to various application specifications (e.g., cell phone screen, household lighting form factor, TV size, and the like). Lengths may be chosen according to various materials properties (e.g., thickness  2014  may be chosen according to the index of refraction of light guide  2010 , an angle associated with TIR in light guide  2010 , a specification for light quality exiting light guide  2010  (e.g., a requirement that light be within a few degrees of normal to second surface  2030 ), and the like. 
     Light from a light source may be transmitted through first surface  2020  into light guide  2010 . First surface  2020  may be at least partially reflecting (e.g., a half mirror), and may be configured to reflect light arriving at first surface  2020  from within light guide  2010  back into light guide  2010 . First surface  2020  may be flat, curved, or otherwise shaped. First surface  2020  may be disposed at an angle  2022  with respect to one or more other surfaces of light guide  2010 . Angle  2022  may be between 45 and 135 degrees, between 70 and 110 degrees, and/or between 80 and 100 degrees. In some cases, angle  2022  may be chosen according to various predicted angles of internal reflection within light guide  2010 . 
     Light from a light source may be transmitted through fourth surface  2050  into light guide  2010 . Fourth surface  2050  may be at least partially reflecting (e.g., a half mirror), and may be configured to reflect light arriving at fourth surface  2050  from within light guide  2010  back into light guide  2010 . Fourth surface  2050  may be flat, curved, or otherwise shaped. Fourth surface  2050  may be disposed at an angle  2052  with respect to one or more other surfaces of light guide  2010 . Angle  2052  may be between 45 and 135 degrees, between 70 and 110 degrees, and/or between 80 and 100 degrees. In some cases, angle  2052  may be chosen according to various predicted angles of internal reflection within light guide  2010 . 
     Some surfaces (e.g., first surface  2020  and/or fourth surface  2050 ) may be configured to reflect light (incident on the surface from within light guide  2010 ) back into light guide  2010  at one or more preferred directions. In some cases, surfaces may reflect light in a manner that minimizes undesirable transmission of reflected light out of light guide  2010 . In certain cases, light may be reflected at angles less than an incident angle associated with TIR from another surface (such as second surface  2030  and/or third surface  2040 ). 
     Some surfaces (e.g., third surface  2040  and/or optionally second surface  2030 ) may include “mirrors” whose reflectivity depends on the angle of incidence of incident light (e.g., from within light guide  2010 ). An angular dependence of reflectivity may be created via control of the indices of refraction on either side of the surface. An angular dependence of the reflectivity may be created via other methods, such as nanostructuring of the surface, the use of surface coatings, and the like. In some cases, surfaces are designed such that incident light at a low angle of incidence (e.g., below 45 degrees, below 30 degrees, below 20 degrees, or even below 10 degrees) is reflected. In some cases, surfaces are designed such that incident light at a high angle of incidence (e.g., normal to the surface, within 2 degrees of normal, within 5 degrees of normal, within 10 degrees of normal, and/or within 20 degrees of normal) may pass through the surface. 
     A surface of light guide  2010  may include one or more windows  2060 , which may be opened or closed via various actuation mechanisms. As such, a window  2060  may behave as a light valve. In the example shown in  FIG. 10 , a window  2060  is disposed in third surface  2040 , and light exits light guide  2010  via second surface  2030 . Some implementations include tens, hundreds, thousands, millions, or even billions of windows  2060 . Certain implementations include one, two, three, five, or ten windows  2060 . A window  2060  may be characterized by one or more dimensions  2062 , such as a length, width, radius, and/or other dimensions characterizing various aspects of window  2060 . Windows  2060  may be characterized as “transparent” to substantially all incident light, and may allow for the transmission of light from within the “body” of light guide  2010  to other structures (such as contact domes, reflectors, and the like). A window may be created by contacting a contact dome to a surface. An open window may allow passage of light into a contact dome, where it may be reflected by a reflector. Removing the contact dome (creating a gap) may “close” the window to the passage of light. 
     Reflectors may be a variety of shapes (parabolic, elliptical, linear, curved, flat, and other shapes). A window may have different reflectors associated with different directions of incident light. For example, a shape of reflector  2070  may be chosen according to a preferential receipt of light incident from a direction associated with first surface  2020 . Windows  2060  provide for the passage of light through the window to one or more reflectors. In the example shown in  FIG. 20 , reflector  2070  is disposed in a position to reflect incident light. Reflectors may generally be full mirrors (e.g., completely and/or specularly reflective). Reflectors may be characterized by one or more dimensions. In the example shown in  FIG. 20 , reflectors may be characterized by dimensions  2074 , and  2078 , and may optionally be characterized by other dimensions (e.g., normal to the page). 
     In the example shown in  FIG. 20 , third surface  2040  functions as an angularly dependent mirror via a reflectivity induced by different indices of refraction on either side of the surface. Such an implementation may include reflectors  2070  disposed on a contact dome  2080  fabricated from the same material as light guide  2010 . Contact dome may be actuated by an actuator (not shown) to move in direction  2090 , providing for opening (contacting light guide  2010 ) and closing (not contacting light guide  2010 ) via actuation of contact dome  2080  in direction  2090 . 
     Reflective portions of third surface  2040  may include an air gap, and window  2060  may include an optically transparent contact between the contact dome  2080  and the “body” of light guide  2010 , which may include using smooth, planar mating surfaces. Light having a shallow incidence angle on third surface  2040  (i.e., having an angle with respect to surface normal larger than A) may reflect off third surface  2040 . 
     Light (e.g., light  2000 ) passing through open window  2060  may be reflected by a reflector (e.g., reflector  2070 ) back toward a surface (e.g., third surface  2040 ). Such a reflection may result in reflected light  2000  having a large angle of incidence with respect to third surface  2040  and/or second surface  2030 , which may result in passage of the light out of light guide  2010  (e.g., via second surface  2030 ). Such angles are schematically shown in  FIG. 20  via smaller angles, with respect to surface normals, than TIR angles A. 
     Various dimensions (e.g.,  2062 ,  2070 ,  2074 ,  2014 , and the like) may be chosen according to application requirements. For example, as a radius  2062  of a round window  2060  decreases, light passing through window  2060  may increasingly behave as if arriving at reflector  2070  from a “point source,” which may provide for utilization of a specific geometry for reflector  2070  (e.g., parabolic) that results in light exiting light guide  2010  via second surface  1030  at a substantially normal angle to second surface  2030 . 
       FIG. 21  illustrates an embodiment. Light  2100  may be guided by light guide  2110 . Light guide  2110  may include surface  2130  and surface  2140 . Surface  2140  may be at least partially reflective, and may reflect incident light that arrives at an angle of incidence shallower (with respect to the surface) or larger (with respect to the surface normal) of an angle A associated with TIR. In some cases, surface  2140  is bounded by an air gap. 
     Surface  2140  may include a window  2160 , which may be in optical communication with a reflector  2170 , which may be mounted to a contact dome. Actuation of the contact dome may open window  2160 , allowing passage of light from light guide  2110  to reflector  2170 , where it may be reflected and passed back through light guide  2110 . Reflector  2170  may be characterized by a dimension  2172 . In some embodiments, dimension  2172  may be approximately equal to (e.g., within 10% of, 5% of, 2% of, or even 1% of) the size of a pixel of a display device configured to display light guided by light guide  2110 . In some embodiments, a light source provides light that is guided by light guide  2110 . In certain cases, each pixel associated with a display device may be associated with a window  2160  and/or reflector  2170 . 
     Surface  2130  may include a “lens” or other shape associated with transmission of light through surface  2130 . In some cases, a shape of this lens may be chosen to modify an angle of transmittance of light from surface  2130 . For example, mildly divergent light may be modified to become parallel and/or normal to a plane associated with light guide  2100 . 
       FIGS. 22A and 22B  illustrate open and closed windows. In  FIG. 22A , a contact dome  2080  is in contact with a light guide  2010 , allowing for passage of light  2000  into contact dome  2080  via open window  2060 . Light  2000  may then be reflected by reflector  2070  back into light guide  2010  at an angle of incidence that results in transmission of the reflected light through light guide  2010 , exiting light guide  2010  via surface  2030 . In  FIG. 22B , contact dome  2080  is not in contact with light guide  2010 , and so window  2061  is “closed” to the passage of at least low angle light. As a result, light  2000  that might have passed through (an open) window may be internally reflected within light guide  2010 , and may not exit light guide  2010  (e.g., at surface  2030  as shown in  FIG. 22A ). 
       FIG. 22B  also illustrates a mating surface  2222  associated with contact dome  2080 . In some embodiments, a mating surface may be complementary (i.e., matching) at least a portion of a surface of a light guide (such as surface  2040 ). A mating surface between two bodies may create an optically transparent window that substantially allows for the passage of light at any angle of incidence. Opening a gap between the mating surface  2222  and corresponding surface  2040  (e.g., by actuating contact dome  2080 ) opens an air gap at the corresponding surface  2040 , which may result in that region becoming reflecting (e.g., causing TIR for light incident on that region). 
     The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims.