MXPA06010063A - Integrated modulator illumination - Google Patents

Abstract

A spatial light modulator includes an array of elements (204) to modulate light in accordance with image data. The modulator has a display panel having first and second surfaces arranged adjacent to the array of elements such that the second surface is directly adjacent the array of elements to allow a viewer (214) to view an image produced by modulation of light. The modulator may also include a light source (216) to provide light to the display panel and illumination dots (208) on the first surface of the display panel to reflect light from the source to the array of elements.

Description

INTEGRATED MODULATOR LIGHTING FIELD OF THE INVENTION The spatial light modulators used for imaging applications come in many forms. Transmissive liquid crystal device (LCD) modulators modulate light by controlling the rotation and / or alignment of crystalline materials to block or let light in. The spatial light modulators reflectors exploit various physical effects to control the amount of light reflected on the image generating surface. Examples of said reflector modulators include reflective LDCs, and digital micromirror devices (DMD ™). Another example of a spatial light modulator is an interferometric modulator that modulates light by interference, such as the iMoD ™. The iMoD employs a cavity that has at least one mobile or deflectable wall, As the door, usually composed of at least partially metal, moves towards a front surface of the cavity, interference occurs that affects the color of the light visualized on the front surface. The front surface is usually the surface where the image seen by the viewer appears, since the iMoD is a direct vision device. Generally, the iMoD is a flat panel, direct vision, highly reflective screen. Due to its high reflectivity, the iMoD needs little illumination in most lighting conditions. The typical consumer expects to be able to read electronic screens in situations where there is little ambient lighting. Some form of lighting is required for the iMoD and other purely reflective space light modulators that usually use ambient lighting. The back lighting techniques extensively used with LCD do not work for purely reflective spatial light modulators. A purely reflective spatial light modulator is a modulator through which light can not be transmitted from the back to the front in a form that illuminates the elements of the modulator. It is possible to leave spaces between the elements of a purely reflective spatial light modulator to allow the backlight to move through and emerge in the front of the panel, but the light will not contain any image information, since the light actually it does not illuminate the elements, passing them in their path through the screen panel. In one approach, as discussed in the U.S. Patent Application Serial No. 10 / 224,029, filed on August 19, 2002 (Publication Number 20030043157) and shown in the figure, "micro-lamps" 104 are fabricated on the surface of the glass 102 attached to the glass substrate 106 of a purely reflective spatial light modulator arrangement 108. Each micro-lamp has an inherent reflective layer 111 which helps direct light 113 from the micro-lamp to the disposition 108. An anti-reflection coating (AR) 100 reduces the amount of incident light 109 reflected from the surface. The incident light on the arrangement of the modulator 108 travels along the paths 110 through the interface 107 and, eventually, reaches the viewer 111. This approach is somewhat complex and requires an extra glass layer 102, in which the arc lamps and their control circuitry must be manufactured. In an alternative approach in the same U.S. Patent Application, a light tube is used that includes scattering centers. This approach is shown in Figure lb. The light source 116 is mounted on a light guide 118. The light 122 is coupled to the light guide using a collimator 120. The dispersion pad, or scattering center, 124, is an area of the light guide that It has been scraped with a dry or wet etching. The scraped areas are then coated with a thin film stack of an absorbent surface in the direction of the viewer 128 and a reflective surface in the direction of the surface 112 and finally the arrangement of the modulator 114. The light trapped within the light guide enters the contact with the scattering pad 124 and the total internal reflection is disturbed, and a certain portion of the light 129 diffuses in all directions, including toward the modulator arrangement through a reflection outside the thin film stack 126. In either of these approaches, there are some problems. The manufacturing process is much more complicated with the addition of several parts. The addition of glass 102 or light guide 118 adds thickness to the modulator, which can create parallax issues and reduce the visual quality of the image.

SUMMARY OF THE INVENTION In some embodiments, a spatial light modulator comprises means for modulating light in accordance with image data, for displaying an image produced by light modulation, means for reflecting light to the modulation means, and means for illuminating sideways the support means. The deployment means comprises means for supporting the modulation means during the manufacture of the modulation means. The support means have first and second surfaces. The second surface of the support means is directly adjacent to the modulation means to allow a viewer to see an image produced by the light modulation. The reflection means are located on the first surface of the support means. The lateral illumination means are positioned with respect to the support means for injecting light into the support means for light to propagate through the support means due to the total internal reflection of the first and second surfaces. The reflection means are arranged to reflect the light propagating within the support means to the modulation means. In some embodiments, a method for manufacturing a spatial light modulator device comprises providing a transparent substrate having first and second surfaces, making an arrangement of spatial light modulators on the second surface of the transparent substrate, applying reflective elements to the first surface. of the transparent substrate, and placing a light source comprising a side light with respect to the transparent substrate for injecting light into the transparent substrate so that the light propagates through the transparent substrate due to the total internal reflection of the first and second surfaces . The reflection elements are arranged to reflect the light that propagates within the transparent substrate to the spatial light modulators. In some embodiments, a spatial light modulator comprises means for modulating the light in accordance with image data, means for displaying an image produced by the modulation of light, means for reflecting light to the modulation means, and means for illuminating the I return the support means. The deployment means comprises means for supporting the modulation means during the manufacture of the modulation means. The support means have first and second surfaces. The second surface of the support means is directly adjacent to the modulation means to allow a viewer to see an image produced by the light modulation. The reflection means are located on the first surface of the support means. The back lighting means are positioned such that the modulation means are between the support means and the back lighting means. In some embodiments, a method of manufacturing a spatial light modulator device comprises providing a transparent substrate having a first and second surfaces, fabricating an arrangement of spatial light modulators on the second surface of the transparent substrate, applying reflective elements to the first surface of the transparent substrate, and placing a light source comprising a back light adjacent to the transparent substrate.

BRIEF DESCRIPTION OF THE FIGURES The invention can be better understood by reading the description with reference to the figures, wherein: Figures la and Ib show methods of the prior art of methods for illuminating a purely reflective spatial light modulator. Figure 2 shows an example of a spatial light modulator having illumination points. Figures 3a, 3b and 3c show different patterns of lighting point patterns used with a sidelight. Figure 4 shows a mode of a pattern of lighting points used with a backlight. Figure 5 shows modalities of possible positions for lighting points. Figure 6 shows a flow diagram of a method for manufacturing a spatial light modulator with illumination points.

DETAILED DESCRIPTION OF THE MODALITIES Figure 2 shows a mode of a special purely reflective light modulator having lighting points. The spatial light modulator in this example is an interferometric modulator that modulates light by controlling the depth of a cavity between the moving mirrors and the optical films manufactured directly on the transparent substrate 200. Each element 204 of the arrangement includes a miniature mirror suspended from the substrate. These mirrors can be activated individually to modulate the light traveling through the diffuser 206 and through the substrate 200 to reach the element 204. Each modulator element, when activated, can alter the color seen by a viewer 214 on the side opposite of glass. The layer 202 acts as a back plate for the modulator and is generally opaque, making this type of modulator difficult to use with back lighting. Elements such as 204 are opaque, which also makes subsequent illumination difficult. However, with the application of a front lighting scheme, the lighting points 208 formed at the interface between the diffuser 206 and the substrate 200 can provide illumination for the screen. Each point 208 is composed of a first layer 210 which is reflective in the direction of the modulator arrangement and a second layer 212 which is absorbing towards the viewer. This is similar to the leisure centers mentioned above, except that there is no need to add the extra step of wet or dry etching the substrate, since the lighting points can be formed on the surface of the transparent substrate or the diffuser through of various types of printing or thin film deposition techniques. Although not necessary, etching techniques can also be used on the transparent substrate if desired. For purposes of the analysis of the present invention, the display panel may be a combination of the substrate 200 and the diffuser 206, the substrate and an anti-reflective film, or only the substrate 200. The front panel has two surfaces. The first surface is that surface through which the viewer observes the modulated light. The second surface is that which is directly adjacent to the modulator arrangement. The first surface can have the diffuser on it, where it is considered that the points of illumination are on the first surface, regardless of whether they are formed on the substrate or the diffuser. Interferometric modulators can only use ambient lighting. When used to create direct vision screens, they can use input light to form the images seen by the viewer. The lighting points together with a light source associated with the screen can complement the ambient light, increasing the brightness of the screen. In total darkness, the lighting points and the associated light source can provide all the lighting needed for the screen. Figure 2 also shows a light source 216, such as a cold cathode fluorescent tube or a side emitting light tube illuminated by a light emitting diode (LED), which resides on an edge of the transparent substrate 200. Light emitted by the light source and suitably injected into the transparent substrate is displaced through the transparent substrate due to the total internal reflection. It can be seen that the light hitting a point of illumination is reflected in several different directions as shown in points 220 and 222. The placement of the points can be optimized depending on the nature of the lighting and the environment in which it is placed. You can use the modulator. For example, in Figure 3a, the dot pattern is very regular. Points in the dot pattern, such as point 302, scatter light that subsequently strikes the elements of the modulator such as elements 304a and 304b. The scattered light from point 302 could have been reflected several times within transparent substrate 200 before hitting point 302 and begin to scatter. The light injected into the transparent substrate will be reflected internally in the substrate. Without the stitches or some other disturbing surface structure, this light will continue to cross the substrate. With the use of lighting points, the dot pattern can create uniform illumination. Various schemes can be applied to a diverse spacing in a regular manner across the surface of the transparent substrate to create uniform light emission, such as that shown in Figures 3b and 3c. In Figure 3b, the dot pattern is modified, but in a regular form, here called a regular and varied pattern. The dot pattern 3a is shown in dotted lines for comparison. As can be seen, each row, such as that which includes element 302 is displaced from its previous position with a uniform variation. In the particular example of Figure 3b, the first row varies "forward" a particular distance from the previous position, and the second row varies a similar distance "backward". This is just an example of a modified pattern with regular variation. Figure 3c, in comparison, not only uses variation but also includes spatial oscillation, for a regular, varied and oscillating pattern. In general, the points will be of a size too small to be decomposed by the vision of a person who is watching the normal viewing distance screen. Undesirable artifacts can sometimes continue to be created by dispositions with characteristics that can not be broken down individually. Careful design of pattern variation, and / or pattern variation and oscillation and / or fundamental separation and pattern layout can be used to mitigate or eliminate any such undesirable artifacts. The embodiments of Figures 3a-3c are directed to a lateral lighting scheme, essentially a scheme in which the elements are illuminated "in front". It is also possible to use a back lighting scheme. The use of backlight with a purely reflective modulator on a transparent substrate may also suffer from some limitations. The limitations in the use of a backlight with a purely reflective spatial light modulator arrangement arises because the light is shifted from the back of the modulation elements, such as the elements 404a and 404b in Figure 4, to the viewer 216. Light can only pass through very small spaces, such as 406, between the elements 404a and 404b. The designer of the. Modulator generally strives to keep these spaces as small as possible to maximize the reflectivity of the modulator. This limitation can be minimized by placing the points on the upper surface of the transparent substrate directly in the opposite direction to the spaces between the elements. Typically, back lights, such as 416, have uniform lighting characteristics and, therefore, a uniform separation would be appropriate. An example of such a pattern is shown in Figure 4, where points such as 402 are placed to "fill in" the spaces. It is also possible to introduce the variation in the placement of points within the spaces. In addition to the variation in the configuration of the points, the surface on which the points are placed may also vary. Usually, the points will be placed to reside at the interface between the diffuser and the transparent substrate. Figure 5 shows alternate surfaces for the placement of the points in this interface. The diffuser 502 is normally coupled to the transparent substrate 500. For purposes of this figure, the diffuser has been lifted from the substrate. The points could be configured on the surface of substrate 500, such as point 504. Point 504 has a reflective portion 508 in the direction of the modulator arrangement, which is not shown, and an absorbent portion 506 in the direction of the viewer. In an alternative, the dots could be placed on the surface of the diffuser 502, such as point 510. Changing the position of the points can modify the processing sequence of the points. A point on the surface, such as 504, of the glass may have a first reflective material deposited and then covered by a "coating" of absorbent material. If the points reside on the surface of the diffuser such as 510, the absorbent material 512 would be placed first, then the reflective material 514. This maintains the proper orientation of the layers with respect to the modulator and the viewer 214. In addition to the flexibility in the Printing of the dots on either the surface of the diffuser or the surface of the substrate and the flexibility as to what pattern and density the dots are printed, there is considerable flexibility with respect to the point at which the dots are formed in a macturing process. In Figure 6 there is shown one embodiment of a method for macturing a spatial light modulator arrangement with illumination points. A first example of the process starts by providing a transparent substrate at 600. The illumination points are applied to the transparent substrate at 602. The spatial light modulator is then mactured at 604. The modulator will be finished at 606, which can include tasks such as fixing a back plate. The diffuser is then applied to the substrate at 608, above the illumination points. The combination of the diffuser and the transparent substrate can also be referred to as the display panel. The display panel can also comprise any optical components, such as an anti-reflective film. In an alternate mode, the spatial light modulator is fabricated on the "back side" (away from the viewer) of the transparent substrate at 610. The spatial light modulator then ends at 612. In one embodiment, the lighting points are applied to the front side of the transparent substrate at 614 and then the diffuser is applied at 616. In another alternative, at 618 a diffuser is supplied either after the modulator is finalized at 612 or in parallel with the macturing and finishing process of the modulator. The illumination points could then be applied to the diffuser 620 and then the diffuser is applied to the transparent substrate at 622. In any of the above embodiments, the process includes providing a transparent substrate with first and second surfaces, fabricating the spatial light modulator on the second surface, apply the diffuser to the first surface and apply lighting points. There is no implicit order in the list of processes, since the order can change depending on the modality. For example, it may be desirable to place the dots on the substrate or diffuser after macturing the modulator to allow any printing error to be made without affecting the macturing performance of the modulator. If the points are deposited during the macturing process and something goes wrong, this can negatively affect the performance of the process, in the same way an operable modulator can be wasted, in another way. The placement of the points on the modulators that arise from the macture can allow greater flexibility. Depending on how the points are configured, errors could be corrected by cleaning the substrate with acetone or other appropriate solvents and techniques, without there being an effect on the modulator elements sealed behind the substrate. Cleaning procedures performed during macturing can damage the modulator. The formation of the dots themselves can be done in one of many printing processes, including lithographic printing, inkjet printing, screen printing or any other type of printing technique. The points could also be tapered on the surface. Depending on the type of technique used to deposit the points, the shape of the points can be controlled to maximize their effectiveness. As mentioned earlier, the points would be printed at a resolution below the resolution of the human eye to avoid the fact of affecting the quality of the image as seen by the viewer. Therefore, although up to this point a particular embodiment has been described for a method and apparatus for illuminating purely reflective spatial light modulators, it is not intended that said specific references be considered as limitations on the scope of the present invention.

Claims (50)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as a priority: CLAIMS

1. - A spatial light modulator comprising: means for modulating light according to image data; means for displaying an image produced by light modulation, said deployment means comprising means for supporting said modulation means during the manufacture of said modulation means, said support means having first and second surfaces, said second surface of said support means it is located directly next to said modulation means to allow a viewer to see an image produced by the modulation of light; means for reflecting light to the modulation means, said reflection means are located on the first surface of said support means; and means for lateral illumination of the support means, said lateral illumination means being positioned with respect to said support means for injecting light into the support means so that the light propagates through the support means due to the reflection internal total of the first and second surfaces; said reflection means are arranged to reflect said light propagating within said support means to said modulation means.

2. The spatial light modulator according to claim 1, characterized in that the deployment means comprise a screen panel.

3. The spatial light modulator according to claim 1, characterized in that the deployment means further comprise means for diffusing light.

4. - The spatial light modulator according to claim 1, characterized in that the deployment means further comprise means for inhibiting the reflection of ambient light.

5. - The spatial light modulator according to claim 1, characterized in that said modulation means comprise interferometric modulators.

6. The spatial light modulator according to claim 1, characterized in that said support means comprise a transparent substrate.

7. The spatial light modulator according to claim 1, characterized in that said reflection means comprise illumination points.

8. The spatial light modulator according to claim 1, characterized in that said lateral lighting means comprise a light emitting diode.

9. The spatial light modulator according to claim 1, characterized in that said lateral illumination means comprise a light source.

10. A method for manufacturing a spatial light modulator device, the method comprising: providing a transparent substrate having first and second surfaces; making an arrangement of spatial light modulators on the second surface of the transparent substrate; applying reflective elements to the first surface of the transparent substrate; and placing a light source comprising a side light with respect to the transparent substrate for injecting light into the transparent substrate so that the light propagates through the transparent substrate due to the total internal reflection of the first and second surfaces; said reflection elements are arranged to reflect the light propagating within the transparent substrate to the spatial light modulators.

11. - The method according to claim 10, further comprising applying the reflective elements on the transparent substrate before manufacturing the spatial light modulator.

12. - The method according to claim 10, further comprising applying a diffuser to the first surface of the transparent substrate.

13. The method according to claim 12, further comprising applying the diffuser to the first surface of the transparent substrate after finishing the manufacture of the spatial light modulator.

14. The method according to claim 12, characterized in that the application of reflector elements further comprises: applying the reflective elements on the first surface of the transparent substrate after finishing the manufacture of the spatial light modulator; and apply the diffuser after applying the reflector elements.

15. The method according to claim 12, further comprising: providing the diffuser; apply the reflector elements to the diffuser; and applying the diffuser with the reflective elements on the first surface of the transparent substrate.

16. - The method according to claim 15, characterized in that the supply of the diffuser is made after finishing the manufacture of the spatial light modulator.

17. The method according to claim 15, characterized in that the supply of the diffuser is carried out in parallel with the manufacture of the spatial light modulator.

18. The method according to claim 10, characterized in that the application of the reflective elements comprises depositing the reflective elements by screen printing.

19. The method according to claim 10, characterized in that the application of the reflector elements comprises applying the reflector elements by lithography.

20. The method according to claim 10, characterized in that the application of the reflective elements comprises applying the reflective elements by ink-jet printing.

21. The method according to claim 10, characterized in that the application of the reflector elements comprises applying the reflector elements during the manufacture of the spatial light modulator.

22. - The method according to claim 10, characterized in that the application of the reflector elements comprises applying the reflector elements after the manufacture of the spatial light modulator.

23. The method according to claim 10, characterized in that the application of the reflective elements comprises applying the reflective elements in a pattern selected from the group consisting of: a regular pattern, a regular and varied pattern, and a regular, varied pattern and of oscillation.

24. The method according to claim 10, characterized in that the reflector elements comprise illumination points.

25. A spatial light modulator device manufactured by means of the method of claims 10-24. 26 - A spatial light modulator comprising: means for modulating light according to image data; means for displaying an image produced by modulation of light, said deployment means comprising means for supporting said modulation means during the manufacture of said modulation means; said support means have first and second surfaces; said second surface of said support means is directly adjacent to the modulation means to allow a viewer to see an image produced by the light modulation; means for reflecting light to the modulation means, said reflection means are located on said first surface of the support means; and means for back illuminating the support means, said back lighting means being arranged so that the modulation means are between the support means and the back lighting means. 27. The spatial light modulator according to claim 26, characterized in that the deployment means comprise a screen panel. 28. The spatial light modulator according to claim 26, characterized in that the deployment means further comprise means for diffusing light. 29. The spatial light modulator according to claim 26, characterized in that the deployment means further comprise means for inhibiting the reflection of ambient light. 30. The spatial light modulator according to claim 26, characterized in that said means. of modulation comprise interferometric modulators. 31. The spatial light modulator according to claim 26, characterized in that said support means comprise a transparent substrate. 32. The spatial light modulator according to claim 26, characterized in that said reflection means comprise points of illumination. 33. The spatial light modulator according to claim 26, characterized in that said rear lighting means comprise a light emitting diode. 34.- The spatial light modulator according to claim 26, characterized in that said rear lighting means comprise a light source. 35.- A method for manufacturing a spatial light modulator device, the method comprising: providing a transparent substrate having first and second surfaces; making an arrangement of spatial light modulators on the second surface of the transparent substrate; applying reflective elements to the first surface of the transparent substrate; and placing a light source comprising a backlight adjacent to the transparent substrate. 36. The method according to claim 35, further comprising applying the reflective elements on the transparent substrate before manufacturing the spatial light modulator. 37. The method according to claim 35, further comprising applying a diffuser to the first surface of the transparent substrate. 38.- The method according to claim 37, further comprising applying the diffuser to the first surface of the transparent substrate after finishing the manufacture of the spatial light modulator. 39.- The method according to claim 37, characterized in that the application of reflector elements further comprises: applying the reflective elements on the first surface of the transparent substrate after finishing the manufacture of the spatial light modulator; and apply the diffuser after applying the reflector elements. The method according to claim 37, further comprising: providing the diffuser; apply the reflector elements to the diffuser; and applying the diffuser with the reflective elements on the first surface of the transparent substrate. 41.- The method according to claim 37, characterized in that the supply of the diffuser is made after finishing the spatial light modulator. 42. The method according to claim 37, characterized in that the supply of the diffuser is carried out in parallel with the manufacture of the spatial light modulator. 43. The method according to claim 35, characterized in that the application of the reflective elements comprises depositing the reflective elements by screen printing. 44. The method according to claim 35, characterized in that the application of the reflector elements comprises applying the reflector elements by means of lithography. 45. The method according to claim 35, characterized in that the application of the reflective elements comprises applying the reflective elements by ink-jet printing. 46. The method according to claim 35, characterized in that the application of the reflector elements comprises applying the reflector elements during the manufacture of the spatial light modulator. 47. The method according to claim 35, characterized in that the application of the reflector elements comprises applying the reflector elements after the manufacture of the spatial light modulator. 48. The method according to claim 35, characterized in that the application of the reflective elements comprises applying the reflective elements in a pattern selected from the group consisting of: a regular pattern, a regular and varied pattern, and a regular, varied pattern and of oscillation. 49. The method according to claim 35, characterized in that the reflector elements comprise illumination points. 50.- A spatial light modulator device manufactured by means of the method of claims 35-49