MXPA06010129A - Color optimized interference modulator display - Google Patents

Abstract

Disclosed herein are iMoD displays optimized by utilizing different materials for one or more different color subpixels. Such optimized displays have improved color gamut over displays where all subpixels are constructed with the same material. Also disclosed are methods for manufacturing such displays and methods for optimizing iMoD displays.

Description

OPTIMIZED COLOR INTERFERENCE MODULATOR SCREEN FIELD OF THE INVENTION This invention relates to interferometric modulators (iMoDs). More particularly, the embodiments of this invention relate to the optimization of color in the iMoD screens.

BACKGROUND OF THE INVENTION To achieve wide acceptance in the market, a screen technology must have the ability to provide a satisfactory visual experience to the end user. The market for low power and high brightness displays continues to expand, constantly inducing new portable electronic devices. Conventional experience suggests that reflective screens do not have the ability to provide the image quality requirement that is widely accepted in the market. For example, reflective liquid crystal displays (LCDs) experience insufficient reflectivity when used in the office without supplementary lighting and insufficient color spectrum under bright sunlight conditions. As a result, recent market developments have changed the dominant screen for small mobile device applications from reflective to transflective LC displays. The increase in brightness and color spectrum in the transflective screens have increased the cost of energy consumption due to the constant requirement of supplemental lighting, have increased the complexity of manufacturing and have increased their costs.

SUMMARY OF THE INVENTION Another aspect of the present invention is a screen comprising a plurality of pixels, wherein each pixel comprises a plurality of sub-pixels and each sub-pixel is selected from a plurality of sub-pixel types and wherein each pixel comprises at least two sub-pixels that They are of different sub-pixel types. Each type of sub-pixel forms an interference modulator that adapts to reflect light of a different color to other types of sub-pixels. The interference modulator of at least one type of sub-pixel includes at least one difference in its interference modulating components as compared to the interference modulating components of at least one other sub-pixel type.

Another aspect of the present invention is a method of manufacturing a screen comprising making a selection of interference modulating structures and each of the interference modulating structures having the ability to reflect the light of a particular color selected from a group of colors. The optimization method comprises selecting the materials to be used in the interference modulating structures, selecting the thickness of the materials, and selecting the space of the interference modulators independently for each color in the group of colors.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows an iMoD structure. Figure 2 shows an iMoD screen consisting of pixels and subpixels. Figure 3A and 3B show two iMoD structures in which Figure 3B contains an additional gold film. Figure 4 shows a CIÉ color space line of the color space available for two iMoD structures constructed with different materials. Figure 5 shows a slow CIÉ color line of the color and color spectrum parameters for three iMoD color screens that have sub-pixels constructed of the same material. Figure 6 shows the CIÉ color space of Figure 4 with reflective values as a color function for two iMoD structures constructed with different materials. Figure 7 shows a flow chart of a manufacturing process of an iMoD screen, where at least one of the sub-pixels of the screen has a material not found in the other sub-pixels. Figure 8 shows a line of color space CIÉ of the color parameters and color spectrum for two iMoD color screens that have red sub-pixels built with a different material than the blue and green sub-pixels. Figure 9 shows a flow chart of a method for separately optimizing each color sub-pixel in an iMoD screen.

DETAILED DESCRIPTION OF THE INVENTION An alternative for transflective or reflective LCDs are screens that base on iMoDs. In one embodiment, a reflective iMoD screen is provided comprising at least two different color subpixels.

The color subpixels are optimized in such a way that the iMoD screen produces a desired color spectrum. Color optimization can be achieved by selecting the materials of the components, placing the components, and thicknesses of the components independently for each sub-pixel. The subpixel independent color optimization allows to manufacture screens that have a broader spectrum of color that would be available if you use imoDs that have the same structure for all subpixels. Additionally, the color optimization provides iMoD screens that have a wider spectrum of color available than in LCDs. For example, a basic iMoD structure is shown in Figure 1. A partially conductive reflective mirror 502 is deposited on the transparent substrate 500. The support structures 504 on the substrate 500 support the moving conductive mirror 506. The reflection of the mirrors 502 and 506 of the viewing position 508. In a non-stable state, a gap is formed between the moving mirror 506 and the partially reflecting mirror 502. When sufficient voltage is applied through the moving mirror 506 and the partly reflecting mirror 502 , the moving mirror 506 collapses, closing the space. Thus, for example, Figure 1 shows the moving mirror 506 in the collapsed state when a voltage of 7 volts is applied between the moving mirror 506 and the partial reflector 502. Those skilled in the art will recognize that other voltages other than 7 volts can be effective to collapse the moving mirror 506. In contrast, when 0 volts are applied, Figure 1 illustrates that there is a gap between the moving mirror 506 and the partial reflector 502. The reflective spectral characteristics of the iMoD depend on the length of optical path between the moving mirror 506 and the partial reflector 502, which depends on the size of the air space and the thickness and the index of reflected any material placed between the moving mirror 506 and the partial reflector 502. In some embodiments, it is udder the partially reflecting mirror with a dielectric layer in such a way that it trims the moving mirror to prevent the reflecting mirror partially when the mobile mirror He collapses. The thickness of the dielectric layer can also determine the reflective spectral characteristics of the collapsed iMoD. Additional information on the iMoD structures can be found in U.S. Patents. Nos. 5,835,255; 5,986,796; 6,040,937; 6,055,090; 6,574; 033; 6,589,625; 6,650,455; 6,674,562; 6,680,792; 6,710,908; 6,741,377 and 6,794,119. As will be apparent from the following description, the invention can be implemented in any device that is configured to display an image, whether in motion (eg, video) or stationary (eg, still image), and either textual or graphic. More particularly, it is contemplated that the invention may be implemented in association with a variety of electronic devices such as, but not limited to, mobile phones, wireless devices, personal data assistants (PDAs), personal or portable computers, browsers / receivers. GPS, cameras, MP3 music devices, camcorders, game consoles, hand-held clocks, clocks, calculators, television monitors, flat panel displays, computer monitors, automatic displays (eg, odometer display, etc.), controls and / or control screens, camera display screens (for example, screen of a rear view camera in a vehicle), electronic photographs, screens or electronic advertising spots, projectors, architectural structures (for examplend. , roof tracings), packaging, and aesthetic structures (for example, image screen on a piece of jewelry). More generally, the invention can be implemented in electronic switching devices. As described above, the space between the partially reflecting mirror 502 and the moving mirror 506 determines the tone of the light reflected from an iMoD by adjusting the difference in the length of the optical path between the light reflected by the two mirrors. As used in the present invention, "pitch" refers to the color perceived by a human observer of the reflected light. The resulting constructive interference generates color from each iMoD. Figure 2 shows a mode of a color iMoD screen 100. The iMoD 100 screen can be constructed by making a selection of iMoD structures. The structures can be grouped into a selection of pixels 102. Each pixel on the screen comprises three structures iMoD, 104,106, and 108, referred to as "subpixels". The space in each sub-pixel, 104, 106 or 108, is determined in such a way that it has the ability to reflect light in one of the three primary colors. Thus, each sub-pixel, 104, 106 or 108 may be of a different "sub-pixel type". This space is determined during the manufacturing process by placing a protective layer between the partial reflector 502 and the moving mirror 506 (see Figure 1), which is ultimately removed during a final "release" recording procedure. In this way, the space on the screen 100 is designed during manufacture by adjusting the parameters of the procedure for placing the protective material. In some embodiments, each iMoD element 104, 106 or 108 operates as a binary device, switching between a bright state and a dark state. The tone generated by a particular pixel 102 will be determined by which subpixel (s) 104, 106 or 108, in the pixel 102, are in the bright state. Alternatively, a monochromatic iMoD screen including two or more types of subpixels can be provided. For example, a type of blue-green sub-pixel and a yellow sub-type type can be provided to produce a white color by means of the combination of greenish-blue and yellow colors. In one embodiment, a monochromatic iMoD screen comprising a single sub-pixel type, such as a green sub-pixel type, is provided. In some embodiments, each pixel 102 comprises more than three subpixels. In one embodiment, additional subpixels can be adapted to generate additional colors, thereby providing additional subpixel types. In another mode, additional subpixels can be adapted to generate the same three primary colors. Thus, in this mode, the relative intensity of each primary color reflected by a pixel can be determined by how many subpixels of that primary color are in a bright state. Since the thickness of the protective layer partially determines the color of the elements of the iMoD, the possible adjustment of the colors generated is greater. Additionally, the particular adjustment of the available colors that will be manufactured in an iMoD depends on the characteristics of the material used in the iMoD structure and the thickness of the materials used. For example, the material used for the moving mirror 506 can absorb certain wavelengths of light, thereby, reapplying the possible reflected colors. Similarly, the spectral reflection / absorption properties of the materials used for the partial reflector 502, dielectric layers, and substrate 500 may affect the adjustment of the available colors to be manufactured in an iMoD. An example of the iMoD structures is shown consisting of different materials in Figures 3A and 3B. Figure 3A shows an iMoD structure 170 similar to that shown in Figure 1. A partial reflector 150 is deposited on a substrate 152. The support structures 154 support a moving mirror 156. In one embodiment, the moving mirror 156 comprises aluminum, which is advantageous due to its high reflection rate, low cost and ease of placement. Reference will be made to the iMoD structure of Figure 3A in the present invention as the "iMoD structure A". Figure 3B shows an iMoD structure 180 which has been modified by placing an additional gold layer 160 on the aluminum moving mirror 156. Reference will be made to the iMoD structure of Figure 3B in the present invention as the "iMoD structure B". The gold layer 160 may be placed by means of a thin metal film layer in an additional lithographic step before placing and making the pattern of the aluminum layer 156. Those skilled in the art will recognize that alternative materials may be used to achieve the same result. For example, the moving mirror 156 of highly reflective materials can be fabricated instead of aluminum. Additionally, the iMoD B structure can be constructed by fabricating the entire mobile mirror 156 of gold instead of adding the additional gold layer 160 to the aluminum. As shown below, the gold layer 160 improves the red sub-pixels as it absorbs blue light. Alternative metals such as copper can be used to achieve a similar result. The absorption of blue light makes it possible to use more effective iMoD space distances. Each iMoD space distance has the ability to provide constructive interference for reflected light at wavelengths corresponding to multiple integers of twice the distance of space. In that way, several wavelengths of light can be reflected corresponding to the first order interference (wavelength = 2 x space), second order interference (wavelength '= space), and so on. As mentioned above, it is advantageous to use the red sub-pixels with a tuned iMoD space distance to reflect red light through the second order interference. However, said space distances also reflect blue light through the third order interference, inhibiting the practical use of these types of red sub-pixels when only a moving aluminum mirror 156 is used. However, when this third is absorbed Order blue light by gold layer 160, iMoD space distances can be used which produce the second red order light. Alternatively, absorption of blue light can be achieved by including certain oxides that absorb blue light, such as HfO, in the iMoD structure. For example, the oxides can be placed on the substrate as part of the iMoD structure of the red sub-pixels. The oxide layers are advantageously transparent, thereby acting as a filter for blue light while allowing light of other wavelengths to proceed in the iMoD structure. It will be appreciated that reflectors and absorbers that absorb light at wavelengths other than blue, can be used to optimize sub-pixels of colors other than red.

The color perceived from a sub-pixel iMoD (ie, the tone) can be expressed in terms of tri-simultaneous color parameters CIE. The tri-simultaneous CIÉ methods and parameters to obtain them are well known in the art. In several modalities, these parameters can be expressed as X, Y, and Z values; values x, y, and z; Y, x, and z values; Y values, u ', and v'; as well as any other color parameter known in the art. In some embodiments, color parameter pairs such as (x, y) or (u ', v') can be used to graphically display a given perceived color (ie, tone) in a three-dimensional color space line. dimensional. Figure 4 shows the possible adjustment of colors that can be generated using the iMoD structure A 170. Each point of the curve 200 represents the color generated by the structure iMoD A 170 which has a particular space distance between the partial reflector 150 and the moving mirror 156. The space distance is increased by moving according to the clock hands around the curve 200. In one embodiment, each iMoD has the ability to generate only one color, that color may come from any point along the the curve shown in Figure 4. In this way, the curve 200 represents the color design space from which the primary colors of red, green and blue and the corresponding space distances of the selected sub-pixels 104 are chosen (see Figure 2). ). Curve 200 shows that changing the thickness of the space in a sufficient range can vary not only the hue but also the saturation (defined in the present invention as the purity of the tones of the desired primary color) of the resulting colors. The most saturated colors are the result of the second constructive interference of order between the partial reflector and the moving mirror. Figure 4 also indicates the color parameters for the limit of human perception, as defined by means of the CIÉ 1976 color standard (long dotted line 202); standards of color match EBU (squares) red 204, blue 206 and green 208; a white light source D65 210 (circle); and primary colors typically used for the subpixels of a reflective TFT LCD screen 212, 214 and 216 (diamonds). Paxa "maximize the compatibility of iMoD manufacturing with the existing LCD manufacturing infrastructure, certain iMoD designs can use only those materials widely used by the LCD industry, such as aluminum for the moving mirror 156. Additionally, to reduce costs and employ the procedure simpler, identical iMoD structures can be employed for all three primary colors In some embodiments of the present invention, alternative materials are used to construct iMoD pixels to provide alternative color space options.A non-limiting example is the use of the layer 160 gold in the iMoD B 180 structure. In addition, in some modes, not all sub-pixels can be made from the same materials, allowing greater flexibility in color optimization, for example, in one mode, the red sub-pixels are produced according to to the iMoD B 180 structure, while the blue subpixels and Greens are manufactured in accordance with the iMoD A 170 structure. Modifications to the thicknesses or materials that comprise the components that make up an iMoD can result in alternative color design spaces. The dotted curve short 220 in Figure 4 shows an adjustment of design colors that can be generated by means of the structure iMoD B 180. As in the curve 200 for the structure iMoD A 170, each point on the curve 220 represents the color generated by an iMoD B 180 structure that has a particular air space. The air space increases the movement in a clockwise direction around the curve 220. It can be seen that the addition of the gold layer 160 in the iMoD B 180 structure results in the accessibility of different color parameters (u ')., v ') which are accessible by the iMoD structure A 170. In particular, the iMoD B 180 structure can be tuned to obtain the color parameters near the phosphor red EBU 204 that are not available in the iMoD A 170 structure. Ideal screen design requires the balance of image quality parameters such as color spectrum, brightness, and contrast. As used in the present invention, the "color spectrum" refers to the range of perceived colors that can be produced by means of a given screen, "brightness" refers to the perceived amount of light reflected by means of a screen Dadaist; and "contrast" refers to the perceived distinction between the reflection of the bright state and the reflection of the dark state. In some cases, the "color spectrum" can be quantified by the area of the triangle in a CIÉ color space line whose vertices are defined by the color parameters (u ', v') for the red, blue, and green sub-pixels. , respectively. In some cases, the "color spectrum" can be compared to the color spectrum generated by the red 204, blue 206, and green 208 EBU matches. This comparison can be quantified as a ratio of the area of the triangle in a line of color space CIÉ whose vertices are defined by the color parameters (u ', v') for the red, blue and green sub-pixels and the area of the triangle in the color space line CIÉ whose vertices are defined by the red EBU 204, blue 206 and green 208. In some cases, the "contrast" can be quantified as the elation of the bright state reflex to the dark state reflex, both measured under diffuse lighting conditions. The unique ability to adjust the color in a continuous way offers a wide latitude of iMoD screens to perform color spectrum optimization, brightness, and contrast. For example, by selecting various combinations of air space sizes for the iMoD subpixels, multiple color screens can be manufactured using the same iMoD structure design. Figure 5 shows a CIÉ color space line (u ', v') of three iMoD screens manufactured using the iMoD A 170 structure. Three screens are illustrated by triangles in the CIÉ color space line where the parameters color (u ', v') of the primary color subpixels for each screen define the vertices of the triangles. The iMoD 1 250 screen maximizes the reflection of the screen at the cost of the color spectrum, the iMoD 3 252 screen maximizes the color spectrum at the cost of reflection, while the iMoD 2 254 screen represents a compromise between these competition parameters. The color spectrum generated by the red EBU 204, blue 206 and green 208 matches is also represented by the 256 triangle. Table 1 lists several image quality parameters for the iMoD 1250 screen, the iMoD 2 254 screen, and the screen iMoD 3 252. The reflex ratio, defined as the percentage of light reflected from the screen, provides an indication of the relative brightness of the screens. The contrast ratio indicates the contrast between the bright and dark reflection. The color spectrum for the three screens is expressed as a percentage of the color spectrum generated when using the red 204, blue 206, and green 208 EBU matches (note that the relative size of the triangles in the color space line of the Figure 5 for the iMoD screen 1 250, iMoD screen 2 254, and iMoD screen 3 252 as compared to the 256 color spectrum generated by the matches EBU). Table 1 also lists the color parameters (u ', v') for the red, green and blue sub-pixels selected for the iMoD 1 250 screen, the iMoD 2 254 screen, and the iMoD 3 252 screen, as well as the respective color parameters projected white. These results show the balance between the spectrum of color and the brightness and contrast of a reflective screen with the iMoD 1 250 screen that has the highest reflection and contrast ratio while the iMoD 3 252 screen has the highest spectrum of color.

Table 1. Image quality parameters for iMoD screens 1-3, using the iMoD structure A.

The resulting color spectrum in Table 1 also shows that iMoD screens are fully capable of generating a broad color spectrum relative to typical reflective LCDs. All the parameters in Table 1 are determined by the diffuse lighting conditions, with 8 measured degrees of reflection from the normal for the screen. This measurement technique is recommended by measurement standards VESA for reflective screens (see VESA, Standard for Flat Panel Screen Measurements, Version 2.0, 2001 Association of Electronic Video Standards). The performance of the screen measured under diffuse lighting is representative of the actual environment display conditions. Under diffuse lighting conditions, ÍMoD screens can be twice as bright as typical reflective LCDs, and at the same time provide a large color spectrum. Alternatively, iMoD screens can be designed to provide a color spectrum in accordance with those transflective LCDs while in transmission mode, all while maintaining a reflection greater than that corresponding to the reflective LCDs strictly. These specifications exemplify the inherent flexibility of the iMoD screens that feature performance according to the needs for each application. IMoD screens can provide the need for low cost, high reflection screens of unique iMoD structure (screens 1 250 and 2 254 of figure 5), as well as the broader market for larger color spectra, highly reflective screens (screen 3) 252 of Figure 5). In one mode, the color on an iMoD screen 100 consists of sub-pixels 104, 106 and 108 made using the identical iMoD structure materials (i.e., the only difference between the types of sub-pixels is the space between the moving mirror 506 and the partial reflector 502) is optimized to produce the desired characteristics (with reference to figures 1 and 2). For example, to provide a white point equivalent to a D 65 standard white light source 210 (with reference to FIGS. 4 and ), there is a balance between the selection of the primary red and green colors. To maintain a green hue similar to that of green phosphorus EBU 208, the primary red shade can turn green. Alternatively, the primary red is set to a tone similar to that of the red EBU 204 phosphorus, at the time of converting the primary green to red. Once the primary colors are selected, additional fine tuning of the white point and reflection can be achieved by adjusting the ratio of the area of the three primary colors, for example, by entering multiple sub-pixels of the same type (color). These selections of primary colors and area relationships affect all the brightness of the screen 100. In one embodiment, to maximize the brightness of the screen 100, the primary green is adjusted and the primary red becomes green.

Increasing the color spectrum by combining the different iMoD structures The requirement of a balanced white point limits the selection of the primary red color in the previous examples. While iMoD has the ability to produce red colors with a redder and deeper tone, these redder shades have limited brilliance. Figure 6 shows a CIÉ color space line of possible color parameter adjustments that can be obtained from the iMoDs manufactured in accordance with the iMoD structure A170 and the iMoD structure B 180 (with reference to Figures 3A and 3B). Figure 6 is the same line as Figure 4, except that the reflex values 300 for the iMoDs that have color parameters selected in the red region are indicated in the curves for the structure iMoD A 200 and the structure iMoD B 220 Reflection is indicated for various selections of red sub-pixels using, either the iMoD A 170 structure or the iMoD B 180 structure. When the air space in the iMoD A 170 structure is increased (ie, moving clockwise around the 200 curve), it is achieved that the reflection is present substantially before the tone of the phosphor EBU 240. However, by increasing the air space in the iMoD B 180 structure (ie, moving clockwise around the curve 220), a behavior is exhibited alternative, in which the brilliance of the red tone is maintained until the tone moves through the red shadows and into the purple and magenta shadows where the eye's response is more limited.

Since an iMoD structure has the ability to generate the high level of performance specified in Table 1, it is possible to obtain additional gains. By combining the primary colors of the color curve 200 (for the iMoD structure A 170) and the color curve 220 (for the structure iMoD B 180) shown in figures 4 and 6 on a screen, it is possible to obtain performance improvements of the image quality of the screen. This results in improvements in the spectrum of color, reflection and contrast ratio, while maintaining full control of the white point of the screen. Thus, in some embodiments, color screens (such as screen 100 in Figure 2) are provided where at least one of the subpixels of the iMoD structure consists of an iMoD structure that is different from the structures iMoD of other subpixels. Non-limiting examples of differences in iMoD structures include a difference in material selected for one of the components of the iMoD structure, the aggregation or removal of a component, altering the thickness of a component in the iMoD structure, and / or an order different from the components. Non-limiting examples of components in the iMoD structure that can be altered include the moving mirror 506, the partial reflector 502, the dielectric layers, and the transparent substrate 500.

In some embodiments, a monochromatic screen whose bright state color is determined by the combination of two or more subpixels that can be optimized for the monochrome color. For example, a monochromatic white screen may comprise a blue-green sub-pixel and a yellow sub-pixel whose combined colors produce white. The yellow and blue-green sub-pixels as described in the present invention can be optimized independently to produce an optimized white color. In some embodiments, a monochromatic screen comprises a single color sub-pixel, however, that color sub-pixel is optimized as described in the present invention to produce a specific desired color. Similarly, in some embodiments, a single-color sub-pixel or multiple color sub-pixels are optimized on a color screen in such a way that the screen has the ability to produce a specific desired color with higher quality. Thus, in some modalities, color optimization is developed to achieve different results than only a broad spectrum of color. In cases where additional material is included in some iMoD structures, the additional material may comprise any material that has absorption and / or reflection properties that allow or suppress desired wavelengths of light. The material can be metallic or non-metallic. In some modalities, differences in iMoD structures can be achieved by including the steps of additional placement, pattern formation and / or removal of material. For example, to include an additional movie (such as the film 160 in FIG. 3B) on the reflective side of the moving mirror 156, the film 160 can be placed before placing the material of the moving mirror 156. Subsequently, the lithographic pattern can be defined whose iMoD structures on the screen are going to receiving the additional film 160 (for example, whose pixels 104, 106 and 108 in Figure 2 will receive the additional film). Subsequently, the material of the moving mirror 156 can be placed followed by etching to remove the additional film 156 in the selected iMoD structures. In some embodiments, the additional film 156 may be removed during the same "release" engraving that removes the protective layer. Figure 7 shows a flowchart of an embodiment of an iMoD structure manufacturing process. In this embodiment, an iMoD screen 100 is manufactured as in Figure 2 wherein the pixels 102 have sub-pixels 104, 106 and 108 and at least one of the sub-pixels 104, 106 and 108 have a material not found in other subpixels. In the first step 400, several steps of initial material placement, pattern formation and / or removal during which the same structures and materials are created in all sub-pixels 104, 106 and 108 are subsequently developed. Subsequently, in step 402 , the material to be selectively included in at least one of the subpixels is placed. In step 404, patterns of these materials are made as used in lithography so that they can be selectively removed in some, but not all, subpixels. In step 406, further steps of material placement, pattern making and / or removal for all sub-pixels 104, 106 and 108 are optionally performed. In step 408, the removal step is performed to selectively remove the material placed in it. step 402 on subpixels where the material will not remain. In some embodiments, the removal step 408 may also work to remove other material in some or all of the subpixels. Finally, in step 410, any additional step of material placement, pattern making and / or removal for all sub-pixels 104, 106 and 108 is performed. The increased flexibility provided by the modified iMoD structures when selecting the primary colors for An iMoD screen does not have any impact on the available design options when a level of color spectrum or brightness is selected. Figure 7 shows a CIÉ color space line (u ', v') showing the color spectrum of two iMoD screens. The two screens (iMoD 4 screen and iMoD 5 screen) are illustrated by means of triangles in the CIÉ color space line where the color parameters (u ', v') of the primary color subpixels for each screen define the vertices of the triangles. Triangle 350 corresponds to the iMoD 4 screen and triangle 352 corresponds to the iMoD 5 screen. The blue and green sub-pixels of the two screens were manufactured using iMoD 170 structures, while the red sub-pixels were manufactured using iMoD 180 structures. also the color spectrum generated by the red EBU 204, blue 206 and green 208 matches by means of triangle 256. Table 2 lists several image quality parameters for the iMoD 4 350 screen and the iMoD 5 352 screen. In Table 1, the reflection ratio, defined as the percentage of light reflected from the screen, provides an indication of the relative brightness of the screens. The contrast ratio indicates the contrast between the bright and dark reflection. The color spectrum of the three screens is expressed as a percentage of the color spectrum generated when the red EBU 204, blue 206, and green 208 are used. Table 2 also lists the color parameters (u ', v') for the red, green and blue sub-pixels selected for the iMoD 4 350 screen and the iMoD 5 352 screen, as well as the respective projected white color parameters. Table 2 shows that the iMoD 4 350 screen has a comparable contrast ratio and contrast ratio for the iMoD 1 250 screen in Table 1 while displaying a much larger color spectrum. Similarly, the iMoD 5 352 display exhibits a greater color spectrum with only a modest decrease in the ratio of reflection and contrast ratio. Replacing the red sub-pixel on iMoD screens 1, 2 and 3 with a sub-pixel manufactured with an iMoD 180 structure, the chromaticity of the primary red has changed dramatically in and beyond the pitch of the red EBU phosphor on screens 4 350 and 5 352. This result provides an improved useful color spectrum as the range of bright accessible red tones increases.

Table 2. Image quality parameters of iMoD screens 4 and 5, using iMoD structures A and B.

Table 3 details the image quality parameters for the iMoD 4 350 screen and iMoD 5352 screen compared to the transflective and reflective TFT LCDs measured under diffuse lighting conditions. Comparing the image quality performance of the iMoD 4 350 and 5 displays with the transflective or reflective LCDs shows dramatic differences. IMoD screens have the ability to provide reflective levels greater than two times reflective TFT LCDs, and at the same time simultaneously provide a greater color spectrum.

The higher the brightness of the screen, the more • dramatic effect on the use model of reflective screens. Reflective screens with low energy benefits can easily be read in small, low-light office spaces without the need for. supplementary lighting. Additionally, the increased efficiency of the iMoD screen reduces the need for required lighting of the supplemental lighting system to read in dark environments. Energy is saved by the bi-stable nature of the iMoD screen and minimal dependence on supplemental lighting.

Table 3. Typical image quality parameters for transflective and reflective LC displays.

The iMoD screens are also favorable when compared with the transflective LCDs. The nature of the transflective commitment needs the use of dark light under all conditions except bright sunlight. While in this transmission mode, the screen has the ability to provide a bright image with a large color spectrum (-46% of the EBU color spectrum). However, while in a simple reflective mode, the reflection is reduced to 10% or less, the white spectrum is reduced to 6% of the EBU color spectrum. Alternatively, the iMoD 5 352 screen has the ability to provide a May reflective level at 20% and a color spectrum of 50% of the EBU color spectrum, all while in the reflective mode only. The supplementary lighting in the case of the iMoD screen can, increase the color spectrum of the screen in a similar way as in the case of the transflective screen.

Screen optimization methods In some embodiments, methods for optimizing color iMoD screens (such as screen 100 in Figure 2) are provided. As described in more detail above, the reflected color of a particular iMoD structure can be tuned by varying the materials at the time of manufacturing the iMoD structure, as well as, selecting the interference space in the iMoD structure. Thus, methods that individually include the selection of materials and spaces for each color sub-pixel (such as sub-pixels 104, 106 and 108 in Figure 2) on an iMoD screen are provided. Such selections can be made based on the pattern of the interference properties and the spectral properties of the material. Additionally or alternatively, before the manufacture of the iMoD screens is completed, the initial image quality performance studies in the iMoD test structures can be developed. Subsequently, these structures can provide the opportunity to optimize the iMoD structure and quantify the color performance of different iMoD designs. One embodiment is shown for individually optimizing each color sub-pixel on an iMoD screen in the flow chart of the screen 9. In step 450, one of the desired sub-pixel colors is selected (eg, red, green, or blue) . In step 452, the materials that are to be used to manufacture various elements in the iMoD for that sub-pixel are selected. These materials can be selected to optimize the particular characteristic of the reflected color of that sub-pixel (e.g., selecting the gold to be used in the moving mirror in the iMoD B 180 structure in Figure 3B). In step 454, the thickness of each material is selected, considering the reflection, contrast and desired color characteristics for that color sub-pixel. In step 456, the air space for the selected sub-pixel is determined based on the desired color characteristics for that sub-pixel. At decision step 458, it is determined if there is any other sub-pixel of color that is to be included in the screen and that has not yet been optimized. If so, the procedure returns to block 450 to optimize that sub-pixel. If not, the procedure proceeds to block 460 to complete the optimization.

Claims (35)

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 screen, comprising: means for modulating the light by selecting the reflective lux of a first color, said modulation means of the first color comprising a first means for interfering the light including the means for absorbing the light of a third color; and means for modulating the light by selecting the light reflection of a second color, said modulation means of the second color comprising the second means for interfering with the light, which excludes the means of absorbing the third color.

2. The screen according to claim 1, characterized in that said modulation means of the first color comprises a first sub-pixel and said modulation means of the second color comprises a second sub-pixel.

3. The screen according to claim 1 or 2, characterized in that said first light interference means comprises a first interferometric modulator and said second light interference means comprises a second interferometric modulator.

4. The screen according to claim 3, characterized in that said means of absorbing the third color comprises a layer of material.

5. The screen according to claim 4, characterized in that said first interferometric modulator comprises the first and second reflective surface, one of which comprises said layer of absorbent material.

6. The screen according to claim 4 or 5, characterized in that said material is metallic.

7. - The screen according to claim 4 or 5, characterized in that said material is not metallic.

8. The screen according to claim 4 or 5, characterized in that the material comprises gold or copper.

9. The screen according to any of claims 4-8, characterized in that said first or second reflecting surface comprises said layer of absorbent material comprising a moving mirror.

10. - The screen according to any of claims 4-8, characterized in that the material comprises a film placed in the moving mirror.

11. The screen according to any of claims 4-8, characterized in that the material adjacent to a partial reflector is placed.

12. - The screen according to any of claims 4-8, characterized in that the material adjacent to a dielectric layer is placed.

13. The screen according to any of claims 4-8, characterized in that the material adjacent a substantially transparent substrate is placed.

14. The screen according to any of claims 1-13, characterized in that said modulation means of the first color is adapted to substantially reflect the red light through the second order interference and said absorption means of the third is adapted. color to absorb the reflected blue light through the third order interference.

15. The screen according to any of claims 1-14, characterized in that the first color is substantially red.

16. The screen according to claim 15, characterized in that the first color is red substantially reflected through the second order interference.

17. The screen according to any of claims 1-16, characterized in that the third blue colors substantially.

18. The screen according to any of claims 1-17, further comprises the means for modulating the light by selecting the reflective light of a fourth color, said modulation means of the fourth color comprising the third means for interfering the light.

19. The screen according to claim 18, characterized in that said modulation means of the fourth color comprises a third sub-pixel.

20. The screen according to claim 18 0 19, characterized in that said third light interference means comprises a third interferometric modulator.

21. The screen according to any of claims 18-20, characterized in that the second color is greenish blue substantially and the fourth color is substantially yellow.

22. The screen according to any of claims 18-21, characterized in that the second color is substantially green and the fourth color is substantially blue.

23. - A method for manufacturing a screen comprises: forming a first interference modulator having a light absorption element; and forming a second interference modulator that excludes said light absorption element, said first interference modulator that modulates the light which is a different color than said second interferometric modulator.

24. The method according to claim 23, characterized in that the first interference modulator is manufactured to reflect the red light substantially through the second order interference.

25. The method according to claim 23 or 24, characterized in that the light absorbing element absorbs the blue light substantially.

26. The method according to claim 25, characterized in that the light-absorbing element substantially absorbs the blue light reflected through the third order interference.

27. The method according to any of claims 23-26, characterized in that the light-absorbing element is generated by the placement and pattern formation.

28. - The method according to any of claims 23-27, characterized in that the light-absorbing element comprises a metallic material.

29. The method according to any of claims 23-27, characterized in that the light absorbing element comprises a non-metallic material.

30. The method according to any of claims 23-27, characterized in that the light absorbing element comprises gold or copper.

31. The method according to any of claims 23-30, characterized in that the light absorbing element is placed adjacent to a moving mirror.

32. The method according to any of claims 23-30, characterized in that the light-absorbing element adjacent to a partial reflector is placed.

33.- The method according to any of claims 23-30, characterized in that the light absorbing element adjacent to a dielectric is placed.

34.- The method according to any of claims 23-30, characterized in that the light absorbing element is placed adjacent to a substantially transparent substrate.

35. - A screen manufactured according to the method of claim 23.