JP2007525692A - Structured transflector for liquid crystal displays - Google Patents

Abstract

  According to the present invention, a color transflective display device uses a transmissive display unit that has a viewing side and a back side and that defines pixels. The structured transflector is disposed on the back side of the color display unit. The structured transflector comprises a structural surface and a layered dielectric reflector disposed over the structural surface.

Description

  The present invention relates generally to displays, and more particularly to a transflective (semi-transmissive) display that operates under ambient illumination and also includes backlight illumination.

  The physical miniaturization of microprocessor-based technology has led to the development of portable personal computers, multi-pocket books, wireless telephones and pagers. What is commonly required for these devices and all other devices such as table clocks, watches, calculators, etc. is low power consumption to extend the effective operating period during battery replacement or battery charging A common need for data display screens.

  The most common type of display in such devices is a liquid crystal display (LCD). LCDs may be classified based on the illumination source. A reflective display is illuminated by ambient light incident on the display from the front. A reflective surface such as a brushed metal reflector located behind the LCD reflects the light transmitted by the LCD while maintaining the polarization orientation of the light incident on the reflective surface. While reflective displays meet the need for low power consumption, this display is only useful under good ambient lighting conditions. Under low levels of ambient light, the display is often dark and difficult to read. Thus, a fully reflective display has limited utility.

  Another type of LCD display is a backlit display, where light is generated behind the display and passes through the display to the viewer. Generally, a backlight assembly includes a light emitting diode (LED), a fluorescent lamp or another device that emits light, and a plurality of optical elements for directing light from the light emitter to the LCD. Backlighting can also be used to supplement reflective displays because it can be used for various ambient light conditions. However, the introduction of a backlit assembly also increases battery power consumption and significantly shortens battery life or charge intervals.

  Depending on the combination of the peripheral reflective display and the backlight illumination, a “semi-transmissive” film is required. The transflective film is disposed between the LCD and the light source and is used to reflect ambient light transmitted through the LCD and transmit light from the light source to illuminate the LCD.

  However, under ambient lighting conditions, transflective films often cause specular reflection of incident light that overlays the images, making it often difficult to see the images. This is especially true when the display is a color display operating in backlight mode and there is a high level of ambient light. Therefore, there is a need for an improved transflector that improves the visibility of images on a color display when operating with high levels of ambient light. The transflector may be configured to reflect and transmit light with reduced color shift and diffuse ambient light reflected over a desired angular range.

  In certain embodiments, the invention relates to a transflective display device comprising a transmissive display unit having a viewing side and a back side and defining pixels. The light source is disposed on the back side of the transmissive display unit. The structured transflector is disposed between the transmissive display unit and the light source. The structured transflector comprises a structured surface and a layered dielectric reflector disposed over the structured surface.

  In another embodiment, the present invention relates to a transflective display device comprising a color transmissive display unit having a viewing side and a back side, and a structured transflector disposed on the back side of the color display unit. The structured transflector includes a structured substrate having a structured surface and a dielectric partial reflector disposed on the structured surface. Ambient light incident on the display unit produces glare light in the glare direction, and the structured transflector reflects image light over a range of directions that substantially surround the glare direction.

  The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The following drawings and detailed description embody these embodiments in further detail.

  The present invention will be more fully understood from a review of the following detailed description of various embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

  While the invention is applicable to various modifications and alternative embodiments, its specification is shown by way of example in the drawings and will be described in detail. However, it should be understood that the invention is not limited to the specific embodiments described. On the contrary, it is intended to cover all modifications, alternatives, and variations encompassed within the spirit and scope of the invention as defined by the appended claims.

  The present invention is applicable to a transflective display, and is particularly useful for a color transflective display. Since reflected image light is separated from surrounding glare, the visibility of an image seen by a viewer is improved. It is thought to improve.

  A schematic diagram of a transflective display 100 is shown in FIG. In general, a display unit 102 such as a liquid crystal display (LCD) is connected to a controller 104 that controls information displayed on the display 102. A semi-transmissive body 106 formed of an optical film having one or more layers is disposed under the display unit 102. The power source 108 can supply power to the light source 110 in addition to the display controller 104 and the display unit 102. The light source 110 may be any suitable type of light source, such as, for example, one or more fluorescent tubes, one or more light emitting diodes. The light source 110 can include an optional reflector 111 to direct light in a preferred direction. The power source 108 may be a battery, a rechargeable battery, or other power source.

  The display unit 102 generally comprises an upper absorbing polarizer 112 and a lower absorbing polarizer 114. The liquid crystal layer 116 is sandwiched between the upper absorbing polarizer 112 and the lower absorbing polarizer 114. A glass layer (not shown) may be sandwiched between the absorbing polarizers 112 and 114 and the liquid crystal layer 116. The display unit 102 operates by changing some polarization of the light that passes through it. The color filter 118 is generally used to provide a specific color to a specific pixel of the display unit 102.

  A color display generally operates in a backlight mode. However, under strong ambient light conditions such as strong sunlight, the color display is difficult to see and the image appears faint. Under such circumstances, it is useful to use a combination of both backlight and ambient light to form an image, which looks brighter and easier to see when the ambient light is strong. The semi-transmissive body 106 reflects ambient light that has passed through the display unit 102 and transmits light generated by the backlight to the display unit 102. Thus, the display 100 can operate using backlight, ambient light, or both.

  Here, the operation of the display 100 for light of different polarization states will be described. The polarized ambient light 120 transmitted by the absorbing polarizer 112 is transmitted to the lower absorbing polarizer 114 through the liquid crystal layer 116. When the light that has passed through the liquid crystal layer 116 is in a polarization state that passes through the lower absorption polarizer 114, the light is transmitted and reaches the semi-transmissive body 106. The reflected light 122 from the translucent body 106 passes back through the display unit 102 and is seen by a viewer. At other locations on the display unit 102, the light 124 that reaches the liquid crystal layer reaches the lower absorbing polarizer 114 in an absorbed polarization state. Thus, light does not reach the viewer from this point on the display unit 102. Thus, an image of the reflected light is provided to the viewer by controlling different color pixels to either block or reflect light.

  Ambient light (not shown) that is incident on the upper absorbing polarizer 112 with another polarization different from the light 120 and 124 is absorbed by the upper polarizer 112.

  The backlight image is formed for the viewer as follows. The light source 110 generates light 112 incident on the backlight unit 126. In the illustrated embodiment, the backlight optical unit 126 may include a light guide 128 for directing light from the light source 110 across the display 100 and reflecting to emit light upward toward the display unit 102. You may have a body. In one embodiment, the light guide 128 may comprise a transmissive wedge having its thick end 130 illuminated by the light source 110. Diffuse reflective pads 132, 134 along one or both of the top and bottom surfaces of the light guide 128 may be used to extract light from the light guide 128 toward the display unit 102. The backlight unit 126 also includes a reflector 136 below the optical waveguide 128 and reflects light transmitted through the lower surface of the optical waveguide 128. The reflector 136 may be a diffuse reflector or a specular reflector.

  The backlight unit 126 may also include one or more light manipulation optical films 138 for manipulating light passing to the display unit 102. For example, the light manipulation optical film may comprise one or more prismatic ridged brightness enhancement films to guide light closer to the display axis 140. One approach is to use a two-layer prismatic brightness enhancement film, with the direction of one layer of the prismatic ridges oriented substantially perpendicular to the direction of the prismatic ridges of the other layer, and the display axis 140. Is to guide light in two dimensions. The backlight unit 126 may also include a reflective polarizer for reflecting light to the diffuse reflector 136, and other light is absorbed by the lower absorbing polarizer 114.

  Part of the light 142 emitted toward the semi-transmissive body 106 passes through the lower absorbing polarizer 114 and reaches the liquid crystal layer 116. The polarization of the light emitted from the liquid crystal layer 116 to the upper absorbing polarizer 112 is in a polarization state that passes through the upper absorbing polarizer 112 and is emitted toward the user as the image light 144. Other light 146 transmitted toward the display unit 102 is transmitted through the lower absorbing polarizer 114 and is incident on different portions of the liquid crystal layer 116. In this case, the light 146 is absorbed by the upper absorbing polarizer 112 and reaches the upper absorbing polarizer 112 in a polarization state that is not seen by the user. Accordingly, the spatially selected polarization control of light passing through the display unit 102 from the backlight unit 126 results in the user viewing an image formed by the light emitted from the light source 110.

  It should be appreciated that in some situations, the transflector 106 may not reflect 100% of incident ambient light and may not transmit 100% of the incident backlight. This allows the display 100 to operate as a non-inverted display, for example, the illuminated blue pixels remain the illuminated blue pixels for both ambient and backlight illumination. .

  Before describing the transflector 106, it is useful to consider the difference between a monochrome display and a color display. A monochrome display is generally used in a portable device such as a wristwatch or a mobile phone. The type of information displayed on a monochrome display has many alphanumeric characters and little graphics information. Such information does not require high spatial resolution or grayscale resolution and requires certain color characteristics, so when facing, for example, by moving through sunlight, fluorescent lighting and incandescent lighting Large variations in light characteristics have little impact on the quality of images produced by monochrome displays. Therefore, a common default mode for operating a monochrome display is to extend the life of the battery under ambient illumination, and the backlight is only used as an auxiliary device when the ambient light is insufficient . A transflector in a monochrome display generally has a reflectivity in the range of 60% to 90%. In addition, the use of backlights in monochrome systems sometimes results in reversal of image colors. What appears to be dark on a light background under ambient lighting is bright on a dark background under backlighting. In the case of a monochrome display, such inversion may be inconvenient for the user, but still maintain a visible image.

  Color displays have much more stringent requirements than monochrome displays. First, it is important to maintain color balance in the displayed image regardless of ambient lighting conditions. The user is unlikely to prefer a display in which the color of a particular image changes significantly when moving from a room illuminated by an incandescent lamp to a room illuminated by a fluorescent lamp. One application in which color displays have become commonly used is laptop computers. The display in a laptop computer is generally a transmissive display that uses only backlight illumination to form an image. This ensures a constant color balance and gray scale. Due to the lack of contrast between the image and the ambient light reflected from the display screen under strong ambient light conditions such as direct sunlight, the image on a fully transmissive display becomes faded. Thus, under some lighting conditions, a fully transmissive display becomes useless.

  Adding a transflector to a color display provides an image that is formed using incident ambient light with a backlight. Therefore, the color display can operate in various lighting conditions. Since the default mode for operating a color display is generally the backlight mode, the transflector 106 transmits a significantly higher percentage of the backlight than the monochrome display. For example, the transmissivity through the semi-transmitter is in the range of about 10% to 99%, with a preferred range of about 70% to about 90%. Assuming no absorption in the semi-transmitter 106, this results in a semi-transmitter reflectivity in the range of about 10% to about 30%.

  Furthermore, color reversal in color displays will result in images that look like color negatives produced by photographic film. Since such images are generally unfavorable to the user, the type of transflector that can be used with a color display is a non-inverted transflector. By using a non-inverted transflector, such as a partial reflector / partial transmissive body, a peripheral image can be added to the backlight image and the display can be used under a combination of ambient and backlight illumination.

  A schematic cross-sectional view of a particular embodiment of non-inverted transflector 206 is shown in FIG. 2A. The semi-transparent layer 210 includes a first microstructure layer 212 and a second microstructure layer 214. Between the two microstructure layers 212 and 214 is a partial dielectric reflector 216 that conforms to the shape of the microstructure layers 212 and 214. The microstructure layers 212 and 214 are generally optionally formed from a light transmissive polymeric material.

  While metal partial reflectors have found widespread use for transflectors in monochrome displays, metal transflectors are not well suited for use with color displays. In a monochrome display, the transflective reflectance is relatively high, for example in the range of 60% to 90%. As a result, a metal semi-transparent body is made from a relatively thick layer of metal.

  In a color display, the reflectance of the partial reflector is even lower and may be in the range of 10% to 30%. There are a number of disadvantages with metallic partial reflectors having this range of reflectivity. The reflectivity of the metal layer depends on its thickness. Such low reflectivity requires very thin metal films and is difficult to deposit uniformly. Further, the color of the metal partial reflector having a low reflectance is different from that of the metal partial reflector having a higher reflectance. For example, a thin silver coating with a low reflectivity transmits a higher percentage of blue light than a higher reflectivity coating, so the reflected image looks generally yellow. Furthermore, a thin metal layer is lossy and a few percent of the light is lost due to absorption.

  Pearlescent and pigment reflectors are also not well suited for use with color LC displays. Because the reflectivity and diffusivity levels are generally linked, the display unit design variables are significantly constrained. Furthermore, since the polarization of the scattered light is not maintained, it introduces additional losses to the polarization dependent LC display.

  A preferred technique for forming the partial dielectric reflector 216 is to form a layered dielectric structure. A layered dielectric structure comprises a plurality of dielectric layers with different refractive indices. An example of a layered dielectric reflector 216 is a single layer of relatively high refractive index material disposed over a lower refractive index structural surface. In this case, the upper layer of the material having a relatively low refractive index may be on a side different from the lower refractive index structural surface of the relatively high refractive index layer. Examples of upper layers include an air layer or a planarization layer such as layer 214.

  In another approach, multiple pairs of alternating high and low refractive index materials may be formed to form a dielectric reflector. In the case of reflections optimized for a particular wavelength λ, the different layers have an optical thickness that is an odd multiple of a quarter wavelength (λ / 4). In the case of reflections optimized over the wavelength range, the layer thickness may vary. The number, thickness, and refractive index of the layers may be selected to form a partial reflector having a desired reflectivity over a selected wavelength range. Furthermore, you may adjust the reflectance of a partial reflector so that it may adapt to the specific incident angle in a partial reflector.

  Any suitable material may be used for the high and low refractive index layers. For example, polymers may be used in different layers. Furthermore, fluorinated polymers generally have a low refractive index and may be particularly convenient for use in one or more low refractive index layers. Polymers having dispersed nanoceramics may have a high refractive index and may be particularly convenient for use in one or more high refractive index layers. Non-polymer dielectric materials may also be used. Certain metal-based materials useful for one or more high refractive index layers include titanium dioxide, tin oxide, indium tin oxide, and zinc sulfide. Some non-polymeric materials that may be useful for relatively low refractive index layers include magnesium fluoride, silicon dioxide, and the like.

  In a semi-transparent embodiment having a single layer dielectric reflector, the refractive index of the substrate is in the range of about 1.3 to 1.8, and the refractive index of the dielectric reflector is about 1.8 to 2.3. Is in range. In the absence of a planarization layer, the refractive index of the material on the dielectric reflector is about 1 if the reflector is in air. In the presence of a planarizing layer, the refractive index of the material on the dielectric reflector is considered to be in the range of about 1.3 to 1.8.

  In another approach, referred to as “pile of plate”, the layered dielectric reflector may comprise multiple layers of dielectric material, the thickness of which is a specific quarter of the optical thickness. It need not be selected to be an odd integer multiple of one wavelength. In such cases, such interlayer reflections need not be coherent as in the case of quarter-wave stacks.

  One advantage of using a dielectric reflector layer is that, unlike metal reflectors, color quality is not directly linked to reflectance values. Instead, the reflectance value is related to the refractive index difference between the layers and the number of layers. Also, the dielectric reflector does not introduce absorption loss. Further, for example, diffusing particles may be introduced into the semi-transmissive body in one or more reflective layers or adjacent layers. Since the diffusing particles may be formed from a material having a small difference in refractive index from the host material, the size of the scattering angle may be reduced and the amount of depolarization is also reduced. Therefore, unlike the pearl luster reflector, the level of the reflectance of the dielectric translucent body is not linked to the amount of diffusion, so there is room for further design freedom.

  One approach to forming the semi-transparent body 206 is to first form one of the microstructure layers 212 and 214 using a suitable technique for forming the microstructure surface. For example, the lower microstructure layer 212 may be formed by using a patterning tool for forming the microstructure layer 212 on the substrate 218. In another approach, the lower microstructure layer 212 may be hot stamped on the substrate 218. The lower microstructure layer 212 may be made of the same material as the substrate 218 or may be made of a material different from the substrate 218. Once the microstructured surface is formed, a partial reflector 216 is deposited on the microstructured surface. The substrate 218 may be formed from a relatively soft material such as a polyester film, polycarbonate (PC) film, triacetate cellulose (TAC) film, or a relatively rigid substrate such as a thick PC layer, acrylic layer, glass layer, etc. May be formed. The substrate 218 may be separate from other components in the display, or may comprise separate display components. For example, the substrate 218 may be the lower surface of a display unit, such as a glass layer or an absorbing polarizer, for example. In another example, the substrate 218 may be a layer of a backlight optical element unit 138, such as a reflective polarizer, such as a multilayer reflective polarizer or a cholesteric polarizer. The reflective polarizer may form part of the backlight optical element unit 138.

  The remaining microstructured layer 214 may be formed using a planarization process such as knife coating or calendaring. For the planarization treatment, a material such as a radiation-cured acrylate or a solvent cast polymer may be used. The upper microstructure layer 214 may be formed of a material that can withstand the long service life of the partial reflector 216.

  Optional layer 220 is a further adhesive layer that may be used to secure the transflector 206 to another element, such as a lower absorbing polarizer of the display unit, for example. In another embodiment, the planarization layer 214 can also secure the transflector 206 to the lower surface of the display unit 102 because the layer 220 may be omitted and the layer 214 may be formed from an adhesive material. But there is.

  The pitch P is the length of the reflector 224 that forms the angle of the microstructured partial reflector 216 and may be selected to reduce the moire effect formed between the transflector and the display unit 102. . The pitch may be selected so that more than one angled reflector 224 is associated with each pixel of the display unit.

  The base angle of the angled reflector 224 is denoted θ. The partial reflector 216 may be configured to perform selective angle control in the direction from the incident light 226 to the reflected light 228. Thus, incident ambient light that passes through the display unit 102 may be directed along a preferred direction to avoid glare. Glare tends to result from specular reflection of ambient light incident from the other surface of the display. For example, the transmitted light 230 from the backlight passes through the semi-transmissive body 206 and can pass through the semi-transmissive body 206 without being refracted if the refractive indexes of the layers 212 and 214 are the same. The base angle θ is generally in the range of 2 ° to 20 °, and more preferably in the range of 6 ° to 10 °.

  Another embodiment of the transflector 240 is schematically illustrated in FIG. 2B and shows the substrate 248 secured to the lower layer 252 of the display unit 102 by an adhesive layer 250. A dielectric reflector 246 is deposited on the substrate 248 and the planarization layer 242 forms a substantially flat lower surface 243 in the case of light passing from the light source to the display unit.

  In another embodiment of the transflector 260, a holographic surface 262 is formed on the substrate 264. The holographic surface 262 is covered with a dielectric reflector 266. The dielectric reflector 266 has a surface structure of a holographic surface and functions as a holographic reflector. The dielectric reflector 266 may be structured to preferentially reflect light in directions other than the specular direction due to the shape of the underlying holographic surface. For example, the dielectric reflector 266 may be configured to reflect the ambient light 270 that is incident in the direction of −30 °, not in the direction of + 30 ° in the direction 272 perpendicular to the semi-transparent body 260. The semi-transmissive body 260 may include a planarizing layer 268, and the planarizing layer 268 may be an adhesive layer and may include diffusing particles.

  It is useful to define the direction in which light propagates with respect to the plane of the display. This is done with reference to FIG. The display 300 is in the xy plane. The line 302 perpendicular to the display 300 is called the center line and is parallel to the z-axis. The direction with the + y direction component is called down and the direction with the -y direction component is called up. A direction having a component in the + x direction is called left, and a direction having a component in the -x direction is called right.

  Under certain circumstances, it is useful to separate the reflected image light from the glare, in which case the base angle θ is not equal to zero. This results in image light directed to the peripheral glare peak side. If the angular spacing between glare and reflected image light is about 30 °, the base angle θ is about 10 ° (light is reflected at an angle approximately equal to 2nθ, where n is the light Is the refractive index of the material through which the light propagates before and after being reflected by the reflector.)

  The angular spacing between the reflected image light and the glare is further described with respect to the graph shown in FIG. The center of each graph at the axis intersection represents a centerline parallel to the z-axis. Moving along the axis of each graph represents an increase in angle from 0 ° to 90 °. Since the illumination is assumed to be incident at an angle of 30 ° and directed from the top of the graph, the glare peak 402 representing specular reflection is 30 ° downward from the center.

  Calculated reflections of light from the microstructured translucent body are shown as points 404a-404h. In (a), the base angle of the angled reflector is assumed to be 6 ° and increases by 2 ° for each continuous graph (b)-(h). Therefore, (h) represents a base angle of 20 ° and (c) represents a base angle of 10 °.

  The adhesive layer 220 or another layer may provide diffusion. For example, the adhesive layer 220 may include diffusion particles in the adhesive base material. However, this is generally rotationally symmetric diffusion and produces the same diffusion angle in the left-right direction as in the up-down direction. In certain situations, it may be preferable to spread the image light along the preferred viewing direction rather than providing rotationally symmetric diffusion. Thus, high reflection luminance may be achieved while maintaining high backlight transmittance.

Referring back to FIG. 3, in many portable handheld devices, such as handheld mobile phones, ambient light is typically incident from above and embodied as a beam 310 in the top and center planes. Ambient light is incident on the display 300 at an angle φ _g . The resulting glare may have some degree of angular diffusion due to the small diffusivity, but is generally centered about the beam 312 (at an angle φ _g ). However, it is generally preferred to provide image light to the user in the viewing range around or near the centerline. As a result, it may be advantageous to design the display transflector to provide maximum reflected image light that has a lower brightness for the desired viewing range and other viewing directions.

  One specific technique for performing selective angle reflection control, independent of diffusers that scatter light symmetrically in all directions, is the angle at different angles with respect to the plane of the translucent body. It is to use a semi-transmissive body having a reflector that forms the following. One embodiment of such a semi-transmissive body 506 is schematically illustrated in FIG. For simplicity, only one microstructure layer 508 of semi-transparent material is shown. It should be appreciated that the partial reflector may be arranged to conform to the shape of the microstructure layer 508 and that a planarization layer may be formed over the partial reflector. In the illustrated embodiment, the transflector 506 comprises a collection 509 of three angled reflectors 510, 512, and 514, each having a different base angle θ1, θ2, and θ3. Such a structure may be used to control the diffusion of reflected image light in a plane perpendicular to the axis of the prism forming the reflector by selection of an appropriate range of prism base angles. The pattern of the reflector may be formed to have a repetition of unit cells that is less than or equal to the display pixel (pixel) dimension d of the display unit 502. The collection of reflectors 509 may be some other number of reflectors, for example 2, 4 or more.

  The collection of reflectors 509 can include any desired order of reflectors. For example, the reflectors may be arranged in an order of increasing base angle (as shown), an order of decreasing base angle, or a random order. Further, the reflectors forming the set of reflectors 509 may all have the same pitch, eg, different pitches as shown in FIG. 5B.

  An example of optical results including a collection of reflectors with different base angles is provided in FIG. FIG. 6 shows a graph similar to the graph of FIG. 4 except that the unit cell is formed of reflectors having a plurality of angles, and the base angle ranges from 6 ° to 20 ° by 1 °. . The viewing angle response spreads mainly in the center and upper range. Some diffusion was assumed to match some lateral light spread. Instead, a reflector having an angle with a base angle in the range of less than 10 ° may be used if it is preferred to be filled in the center and the viewing direction below.

  Another approach for performing angle control of the angle range of reflected light is schematically illustrated in FIG. 7A. FIG. 7A shows the microstructure layer 702. A partial reflector layer 704 is deposited on the microstructure layer 702 to have the same shape as the microstructure layer 702. A planarizing layer (not shown) may be added on the partial reflector.

  In this embodiment, the reflector 706 has a non-linear facet 708. Facet 708 may have a radius of curvature, may be aspheric, or may be a series of individual straight segments as shown in FIG. 7B. A plurality of reflectors 706 may be associated with pixels of the display unit. The reflectors 706 associated with one pixel may have the same non-linear shape or different non-linear shapes.

  A graph showing the calculated performance of a semi-transparent body with curved facets ranging from 6 ° to 20 ° facet angles is shown in FIG. 7C. It is clear that it is filled along the center and the top direction, with diffusion added only to accommodate a slight lateral spread. Satisfying different ranges of viewing angles may be achieved using different non-linear profile facets.

  Some type of diffusion is often advantageous to provide some visibility in the left-right direction. The amount of lateral spread may be relatively small compared to the amount of spread at the center and above. Under certain configurations, the reflector facets may be adjusted to form some lateral extent. Such a lateral extension may be formed with rotationally symmetric diffusion, for example from a bulk diffuser, or may be formed without causing rotationally symmetric diffusion.

  An example of a reflector 802 is schematically illustrated in FIG. 8A. FIG. 8A shows a reflector facet 804 having a generally curved surface 806. Another example of a reflector 812 is schematically illustrated in FIG. 8B. FIG. 8B shows a reflector facet 814 having a random or pseudo-random curved surface 816. Such a surface adjustment provides a lateral spread of the reflected light in a direction perpendicular to the slope of the reflector facets.

  The adjustment of the reflector facet may be performed by adjusting the depth of the cutting tool when producing the seed or embossing tool. Adjustments may be aligned for each facet, may be misaligned, or may be random or pseudo-random for each facet. It should be appreciated that other techniques such as using bulk diffuser layers may be used to introduce lateral diffusion.

  In determining the selection of facet angles for use in a semi-transmissive body, a viewing range of certain subset angles may be preferred over other angles. For example, along the center and down direction, the user may want the display brightness to be highest near the center and further lower as the position below the end is sampled. The resulting structure may differ from the structure shown above. The frequency of the base angle or facet curvature that forms the peripheral reflectivity near the central viewing direction has a higher frequency than the base angle / curvature frequency that provides the peripheral reflectivity that contributes to the viewing direction below the end. Selected. This is explained with reference to FIG. FIG. 9 shows the predicted performance of multiple constraints based on changing the frequency of the base angle of a collection of flat reflector facets.

  In the graph, multiple sets of frequencies with different base angles are shown. Curve 902 shows a microstructured surface having only a 10 ° reflector facet. In this case, the groove frequency is 1.0, ie 100% for a 10 ° facet. The normalized axial flux resulting from 1.0 is shown by data point 910. Other patterns are compared against this baseline performance. Curve 904 shows a microstructured surface having 60% 10 ° facets, 30% 9 ° facets and 10% 8 ° facets. Curve 906 shows different frequencies of facets having a base angle in the range of 10 ° to 7 °. Forming facets at an angle of less than 10 ° results in light spreading along the lower viewing direction. However, if the facet frequency with a base angle of less than 10 ° decreases with respect to the frequency of the higher base angle facet, the axial brightness may increase.

  From curves 904 and 906, respective axial luminance values are provided from data points 920 and 930. By maintaining a larger proportion of 10 ° facets, most of the axial luminance performance is maintained while at the same time widening the viewing angle along the center and down directions. For comparison, curve 908 shows a uniform case when the base angle facets in the range of 6 ° to 20 ° have equal frequencies. Corresponding axial performance is indicated by point 940. In this arrangement, the resulting axial brightness is about 30%, significantly lower than the other cases described.

  In another embodiment (not shown), the frequency of facets ranging from 7 ° to 10 ° is the same, 25% per angle. Here, the resulting normalized axial brightness is calculated to be 0.728. Although an equal degree of reflector facet angle is sampled by this configuration as seen in the configuration assumed for curve 906, the resulting axial brightness is higher than for the configuration associated with curve 906.

  By mixing the base angle facets of different frequencies, the reflected angular output of the microstructured semi-transmitter meets the specific requirements of the specific viewing device used, regardless of the symmetric diffusion applied. As such, it may be adjusted or optimized along the preferred viewing direction.

  It should be appreciated that the microstructured semi-transparent material described so far operates in a “groove on top” orientation. In other words, the ambient light first strikes the facet side of the microstructured configuration and is on the opposite side of the plane. Any or all of the described embodiments may be directed to a “groove-down” orientation, where ambient light first passes through the plane of the translucent body before entering the microstructured surface. May be. In order to maintain as much part of the incident ambient light as possible, it is preferred that any layer between the lower polarizer and the transflector of the display unit maintain polarization. The substrate that is a candidate for the “groove below” arrangement may be an isotropic film such as polycarbonate, or an absorbing or reflective polarizer. The incorporation of a reflective polarizer can provide the added benefit of polarization recycling for improved backlight operation.

  A transflector, such as the transflector 206 shown in FIG. 2, uses a single indium tin oxide (ITO) reflective layer 216 on the first microstructure layer 212 formed on the polyester substrate 218. Made. Microstructure layer 212 is composed of 74% by weight aliphatic urethane, 25% by weight hexanediol diacrylate and 1% by weight Darocur 1173, ie 2-hydroxy-2-methyl-1-phenyl-propane-1- It has a composition consisting of ON. The refractive index of the microstructure layer 212 was 1.49. The reflective layer 216 had a quarter wavelength thickness of about 550 nm and a refractive index of 1.9. The planarization layer 214 was formed from a layer of butyl acrylate adhesive having a refractive index of 1.47. A styrene bead was deposited inside the planarization layer 214 to form some kind of diffusion. The base angle θ of the structural layer 212 was 6 °.

  An example called Sample A was compared with the other two displays. Sample B is a commercially available transmissive color LC display, and sample C is a commercially available reflective color LC display, A3013T used in Toshiba cell phones, with a partial metal reflector positioned within the LC unit itself. It has. The different samples are summarized in Table I.

Spotlight measurement Spotlight measurement was performed. In this measurement, the display is illuminated by a collimated light beam incident on the surface at an angle of 30 ° to the vertical, and the detector on the goniometer mount reflects the light reflected from the display as a function of the reflection angle. To measure, it rocked over a certain angle.

  The goniometer spotlight measurement results for the three samples outlined in Table I are provided in FIG. All samples showed a large reflection peak center around + 30 ° cut off from the right of the graph, corresponding to the specular reflection of the irradiated light. The width of this reflection peak was affected by factors such as the divergence of irradiated light and the amount of light diffused during reflection. The results are normalized to reflection from a standard white diffuse reflector, model number SRS-99-020 manufactured by Labsphere (North Sutton, New Hampshire), North Sutton, NH.

  In the case of curve 10-C, which is an internal mirror standard, there was a slight flat area around 10 ° to 14 ° from the vertical, and a very wide viewing angle was seen. A 6 ° structured external semi-transmitter forms a similar reflected luminance peak but with a narrower viewing angle. In the absence of structured semi-transmitter beam guidance control, the OEM-controlled flat semi-transmitter curve 10-B showed an undesirable flat response over the viewing angle range (nominal 0 ° to 15 °).

Backlight illumination The backlight performance of Samples A, B, and C was tested using the same backlight assembly. The backlight assembly used a light guide that illuminates the edge using three LEDs, a diffuser sheet, and two brightness enhancement films. A luminance meter positioned along the normal of the display recorded the axial luminance of the light transmitted through the display. Calculation of the luminance ratio of the display under the test for bare backlight gave the effective transmittance of the display system. The results are shown in Table II.

  Sample A for the 6 ° structured translucent maintained 86% of the original backlight output compared to the transmissive display of Sample B. This was a highly favorable comparison with the transflective display with the internal transflector, ie Sample C. Sample A showed about 2.4 times the backlight brightness of Sample C.

  Different components in each sample that contribute to transmission loss should be considered to account for the difference measured in backlight transmission. The main components of loss include absorption polarizer, aperture ratio (transmission area around patterned mirror or black matrix), color filter and LC polarization response. Assume that the pre-absorption and post-absorption polarizers in Samples A, B, and C show similar transmission, and that Sample C also uses an anti-reflection pre-polarizer. However, this AR process only produces a transmission difference of a few percent.

Color shift (reflected light)
The color of the light reflected during the spotlight test was measured as a function of angle. Color is determined for each measured angle, and the color of the light reflected at each angle is plotted as (x, y) coordinates in the chromaticity diagram of FIG. Curves 11-A, 11-B, 11-C are shown for each sample, with a set of (almost overlapping) points for reflection from the white diffuse reflectance standard shown as 11-D. As the angle of detection changes, there is very little shift in the color of the light reflected from the reflection standard.

  For each of the curves 11-A, 11-B and 11-C, the points corresponding to the measurements taken at 24 ° and approaching the glare peak at 30 ° are noted. Measurements were made to create FIG. 10 and were made at 1 ° intervals over a range of −6 ° to 24 °, corresponding to multiple measurements. In the case of sample A, the spread of the points is relatively small, away from the two points closest to 24 °, indicating that there is almost no color shift in the surrounding image over the range. In the case of curves 11-B and 11-C, there is a substantially large spread, indicating that the peripheral images for these displays show a larger color shift as a function of angle than for sample A. The spread of points in curve 11-A can be further reduced by optimizing the thickness of a single ITO layer and / or adding additional layers in the dielectric partial reflector.

Color shift (transmitted light)
The color of light transmitted by different sample displays was measured.In these measurements, the color of the backlight operating in the absence of the display module was measured first, so the color standard to which the samples of the different displays were compared was determined. Established. The chromaticity meter was positioned along the normal of the display and the color of light transmitted by the different sample displays was recorded. The axial color difference was calculated using the 1931 CIE chromaticity space. The result is shown in FIG.

  As apparent from the bare backlight reference (points 12-A and 12-B, respectively) by small changes in both the x and y color coordinates, in appearance, samples A and B have very little Showing change. Sample C was an internal mirror display and showed the largest color shift (point 12-C).

  In the embodiments described so far, the reflected light is spaced asymmetrically from the glare at an angle. In other words, the image light reflected by the semi-transmitter is preferentially directed to one side of the glare peak. This approach is particularly useful in situations where the position of the viewer and the ambient light source relative to the display is substantially constant, but is not limited to this.

  In another approach, the reflected image light may be directed to substantially surround the glare peak. In other words, the image light reflected by the semi-transmitter propagates in different directions around the glare peak. Under this approach, the viewer can see the image reflected from a wider range of azimuths around the normal to the display. This approach is useful when the position of the viewer and the ambient light source relative to the display is unknown, i.e., variable, but is not limited thereto.

  One particular embodiment of a display 1300 that uses this approach is schematically illustrated in FIG. 13A. The display 1300 includes a display unit 1302 such as a liquid crystal display disposed on the transflector 1306. The semi-transmissive body 1306 includes a substrate 1310 having a structural surface 1312. The dielectric partial reflector layer 1316 is disposed on the surface 1312 and substantially adopts the shape of the structural surface 1312. Dielectric partial reflector layer 1316 may be formed using any of the dielectric techniques described above. An upper layer 1318 may be disposed on the partial reflector layer 1316. The upper layer 1318 may be a planarization layer.

  Rays 1320 and 1322 represent light from ambient light sources. Ray 1324 is reflected by display unit 1302 at an angle θ 1 with respect to the display normal 1330. Ray 1324 represents unwanted glare that interferes with the visibility of the image produced by display 1300. On the other hand, light rays 1326 and 1328 represent light reflected by the structured partial reflector layer 1316 and passed through the display unit 1302. Thus, rays 1326 and 1328 contain image information. Light ray 1326 is reflected from the “ascending slope” portion of partial reflector 1316 and is therefore directed toward the display in a direction closer to normal 1330 at angle θ2. Light ray 1328 reflects from the “down slope” position of partial reflector 1316 and is therefore directed further away from normal 1330 at angle θ 3.

  The substrate 1310 and the structural surface 1312 are shown in more detail in FIG. 13B. The angular range in which the light rays 1326 and 1328 can be reflected by the partial reflector 1316 depends on the shape of the structural surface 1312. In the illustrated embodiment, the structural surface 1312 comprises a plurality of scallops 1332 whose surface makes a maximum angle α with respect to the plane 1334. If the angle α is even larger, the light reflected by the transflector 1306 will spread over a larger angular range. When the scallop 1332 is defined by a well-known curve, for example, when the scallop 1332 is arched, the angle α may be determined from the pitch P and the depth d of the scallop. It should be appreciated that the structural surface 1312 may comprise other types of contours. For example, the structural surface may be a convex surface instead of a concave surface, and a curve different from scallop, for example, a continuous curve such as a sine curve may be used. Furthermore, the structural surface may be formed as a regular pattern or an irregular pattern. The irregular pattern can include, for example, the case where the pitch, the height of the feature, or both are irregular.

  If each reflective unit comprises a surface that varies over an angular range, the structural surface 1312 may be considered to include a plurality of reflective units. For example, each scallop 1332 may have a portion of a surface that spans a range of angles from -α to + α and may be considered a reflective unit. The size of the reflective unit may be less than the size of the pixels of the display unit 1302, in which case each pixel of the display unit 1302 is associated with two or more respective reflective units of the transflector 1306. It may be.

  An example of a structural surface that may be used with a semi-transparent body is schematically presented in FIG. 14A. Surface 1400 is characterized as having an x-axis and a y-axis as shown. A cross section along the x-direction is shown schematically in FIG. 14B. The structural surface 1412 is scalloped with the configuration of adjacent bumps. The spacing or pitch of the bumps may be selected to avoid moiré effects resulting from interaction with other periodic structures in the display, such as the pixelated structure of the liquid crystal display unit. For example, the bump pitch may be selected to form an irrational number when divided by the period of other structures. In another embodiment, the pitch of the bump itself may vary across the surface. The height of adjacent bumps on the surface 1412 may be different. Surface 1412 was also scalloped along the y direction.

  However, it should be appreciated that the cross-sectional shapes in the x and y directions need not be identical and need not be scalloped. For example, the cross section in one or more directions may be a sinusoid as schematically shown in FIG. 14C or may include another shape. Further, the pitch of the surfaces 1412 in each direction may also be selected to avoid other effects that result from moiré effects or interactions with other periodic structures of the display.

  The structural surface 1412 may also be positioned with respect to other periodic structures with small rotations about the normal to the semi-transparent body so that the x- and y-axes of the semi-transparent body are periodic structures. Do not align with the axis.

  With respect to using a planar diffuse partial reflector, the advantage of using a structured transflector as shown in FIG. 14A is that it provides a spread of image light that is reflected over a cone angle of a particular viewing angle, while at the same time from the backlight. It is possible to avoid changing the angular distribution of the image light significantly. Planar diffuse partial reflectors broaden both the reflected ambient light and the backlight. If high axial gain is desired, it is important to keep the backlight parallel.

  The calculated viewing angle cone response for a semi-transmitter as shown in FIG. 14A is presented in FIG. This model was assumed to have a pitch in the x direction of 29.2 μm and a radius of 245 μm, yielding a maximum tilt angle of 3.41 °, a depth or sag of 0.43 μm. In the y direction, surface 1412 was scalloped with a pitch of 87.6 μm and a radius of 502.5 μm, yielding a maximum tilt angle of 5 ° and a sag of 1.91 μm.

  The model is described with reference to FIG. The substantially collimated light beam 1610 is directed to the structural surface of the translucent sample 1600 at a polar angle Φ of −30 ° along the azimuthal direction of 180 ° (from the + y side in the yz plane). The glare peak resulting from the specular reflection of the incident light was found at + 30 ° polar angle Φ along the 0 ° azimuthal direction and became ray 1612. The main reflected light distribution from the structured semi-transparent is shown in FIG. 15 as a gray square surrounding the glare peak (the darker point at the center of the gray area at + 30 ° polar angle and 0 ° azimuth). Has been. The reflected light distribution has a substantially symmetric angular range along both the vertical and horizontal directions.

  By adjusting the maximum inclination of the structure surface, a change in the angular range of the reflected light distribution shown in FIG. 15 occurs. Creating a larger slope increases the angular range of the reflected viewing cone, while a smaller slope reduces the cone size. In the example semi-transparent body 1400, separate slanted contours are formed in two orthogonal directions, namely the x-direction and the y-direction. With such a design, the angular range of the output reflected light distribution is also controlled along these two directions. Accordingly, an orthogonal inclined profile can be selected to form a symmetric or asymmetrical reflected light distribution. However, it should be appreciated that the slope need not be defined only along two orthogonal directions. For example, the structural surface may have a plurality of randomly located round bumps, each round bump reflecting light symmetrically in azimuth and no preferred direction for reflection.

  In order to fine-tune the viewing cone or improve the surface appearance of the display, a slightly diffusing layer may be provided between the structural surface and the liquid crystal display. The transflector may be bonded to the liquid crystal display device using a pressure sensitive adhesive or other suitable adhesive, or a relatively free component or other component element of a backlight illumination system May be associated with a liquid crystal display.

Example A mold for forming a structural surface was made by diamond cutting a copper drum. The drum was rotated and threaded around the drum surface. The design variables for the mold were 39.8 μm thread pitch and 0.53 μm nominal depth to give a maximum predicted tilt of 3 °. The thread was cut with a diamond tool having a cutting edge with a radius of 375 μm. The threading depth was varied by making full use of the depth of the cutting tool with a predetermined sinusoidal variation of 1.16 μm to form a pitch of 87.6 μm. The maximum predicted slope of sinusoidal cutting was 3 °.

  A tool was used to form a structural surface on a substrate using the following method. The resin was distributed between the polyester layer and a portion of the forming tool. The resin was 74% by weight aliphatic urethane, 25% by weight hexanediol diacrylate and 1% by weight Darocur 1173, ie 2-hydroxy-2-methyl-1-phenyl-propan-1-one. It was. The resin was UV cured by directing UV light through the polyester layer. The polyester layer / cured resin sheet was removed from the mold. The cured resin sheet has a structural surface having a sinusoidal cross-section in the downward thread direction as shown in FIG. 14C and a convex lens cross-section in the crossing screw direction as shown in FIG. 14B. It was equipped with. Since the back side of the substrate is black, only reflections from the structured front will be detected.

The distribution of light reflected from the structural surface was tested in the following manner. Consider FIG. 16 showing a test surface 1600. The substantially collimated light 1610 is directed to the surface 1600 and the reflected light is detected by moving the detector in the yz plane. The specular reflected light 1612 is detected at a polar angle Φ _g equal to the polar angle of the incident light 1610. Initially, the reflection was measured from a flat sheet of black polymethyl methacrylate (PMMA). PMMA only produces specular reflection. The distribution of the detection light is shown as a curve 1702 in FIG. Therefore, the cone angle of incident light was about 5.5 ° in full width at half maximum (FWHM).

  The uncoated structural surface was replaced as test surface 1600. A reference point mark shown as arrow 1614 points in a direction parallel to the y-axis (referred to as the 12 o'clock position). The reflected light distribution is shown as curve 1704, which is about 13 ° (FWHM) and has a significantly wider peak than the incident light.

  Next, since the sample was rotated by an angle of 90 ° about the normal line 1602, the reference point mark 1614 points in a direction parallel to the x-axis (referred to as the 3 o'clock position). The distribution of reflected light when the sample is at the 3 o'clock position is shown as curve 1706. The width of the reflected light distribution at the 3 o'clock position was about 11 ° (FWHM).

  Since the sample was further rotated 90 °, the reference point mark 1614 pointed to the -y direction (referred to as the 6 o'clock position). The distribution of reflected light when the sample is at the 6 o'clock position is shown as curve 1708. The width of the reflected light distribution at the 6 o'clock position was about 13 ° (FWHM).

  Finally, since the sample was rotated 90 ° further, the reference point mark 1614 pointed to the −x direction (referred to as the 9 o'clock position). The distribution of reflected light when the sample is at the 9 o'clock position is shown as curve 1710. The width of the reflected light distribution at the 9 o'clock position was about 9.5 ° (FWHM).

  Curves 1704 and 1708 corresponding to the structural surface at the 12 o'clock and 6 o'clock positions overlap almost exactly, indicating that the structure in this direction was positively symmetric about the surface normal. These two curves correspond to the grooves formed on the surface structure in the direction along the threading of the tool.

  Curves 1706 and 1710 correspond to surface structures that are in a direction transverse to the threading of the tool. Curves 1706 and 1710 corresponding to the structural surface at the 3 o'clock position and the 9 o'clock position are close, but do not overlap like curves 1704 and 1708. This suggests that for this particular example, the shape of the structural surface across the threading is less symmetric than when along the threading.

  As described above, the present invention is applicable to a transflective liquid crystal display, and is considered to be particularly useful for reducing specular reflection of ambient light that overlays an image. The present invention should not be considered limited to the particular embodiments described above, but should be construed as covering all aspects of the invention as fully set forth in the appended claims. It is. Various modifications, equivalent processes, and various structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention pertains upon review of this specification. . The claims are intended to cover such modifications and devices.

1 schematically illustrates an embodiment of a transflective display according to the principles of the present invention. Fig. 4 schematically shows a cross section according to different embodiments of a semi-transparent body according to the principles of the present invention; Fig. 4 schematically shows a cross section according to different embodiments of a semi-transparent body according to the principles of the present invention; Fig. 4 schematically shows a cross section according to different embodiments of a semi-transparent body according to the principles of the present invention; Fig. 2 schematically shows a display and coordinates used in explaining the optical path to the display. 2C shows a graph showing the calculated optical response of different transflectors as shown in FIG. 2A for various values of the base angle from 6 ° to 20 °. Fig. 4 schematically shows part of another embodiment of a semi-transparent body according to the principles of the present invention. Fig. 4 schematically shows part of another embodiment of a semi-transparent body according to the principles of the present invention. Fig. 6 shows a graph showing the calculated optical response of a semi-transparent body with reflectors arranged in the range of 6-20 ° angles according to the principles of the present invention. Fig. 4 schematically illustrates an embodiment of a transflector having non-linear reflective facets according to the principles of the present invention. Fig. 4 schematically illustrates an embodiment of a transflector having non-linear reflective facets according to the principles of the present invention. FIG. 4 shows a graph illustrating the calculated optical response of a semi-transparent body having a curved reflector that curves over an angle range of 6 ° to 20 ° according to the principles of the present invention. Fig. 4 schematically illustrates an embodiment of a reflector providing lateral light diffusion according to the principles of the present invention. Fig. 4 schematically illustrates an embodiment of a reflector providing lateral light diffusion according to the principles of the present invention. Fig. 4 shows a graph illustrating the optical effect of a transflector having different combinations of reflectors at different angles according to the principles of the present invention. Fig. 4 shows a graph showing the experimental results of a spotlight test for a reflective display with three different types of transflectors. Fig. 6 shows a graph illustrating the color characteristics of ambient light reflected at different angles for a reflective display with four different types of transflectors. Fig. 4 shows a graph showing color shift in backlight operation for a reflective display with three different types of transflectors. Fig. 4 schematically illustrates another embodiment of a structured semi-transparent body according to the principles of the present invention. 13B schematically illustrates the structured semi-transparent substrate shown in FIG. 13A. Fig. 4 schematically illustrates another embodiment of a structured semi-transparent body according to the principles of the present invention. 14B schematically shows a cross section of the substrate of the structured translucent body shown in FIG. 14A. 14B schematically shows a cross section of the substrate of the structured translucent body shown in FIG. 14A. Fig. 4 shows a graph of this scope showing the calculated distribution of light reflected from a structured transflector made according to the principles of the present invention. Fig. 3 schematically shows a display and coordinates used in describing an experiment to determine the reflection characteristics of a structured translucent body. 3 shows experimental results showing the distribution of light reflected from a structured transflector.

Claims (64)

A color transmissive display unit having a viewing side and a back side and defining pixels, and arranged on the back side of the color display unit, and reflects ambient light that has passed through the color display unit at a reflection angle different from an incident angle A transflective display device comprising a structured dielectric reflector, wherein the transflective display device comprises a structured transflector in which the reflection angle and incident angle are measured relative to a display normal.   The apparatus of claim 1, wherein the dielectric reflector has a transmittance in the range of 70% to 90%.   The apparatus of claim 1, wherein the transmissive display unit is a liquid crystal display unit.   And further comprising a backlight unit for generating a backlight, wherein the structured transflector is disposed between the color display unit and the backlight unit, and the backlight passes through the structured transflector. The apparatus according to claim 1, wherein the apparatus reaches the color display unit.   The apparatus of claim 4, wherein the backlight unit comprises a light source and at least one light manipulation film disposed between the light source and the structured transflector.   The apparatus of claim 4, wherein light from the backlight passes through the structured semi-transmitter in an input direction and exits the structured semi-transmitter in a direction substantially parallel to the input direction.   The structured reflector defines a plurality of sets of reflective facets, the reflective facets are non-perpendicular to the optical axis of the display device, different sets of reflective facets are associated with each different pixel, and the reflective facets The apparatus of claim 1, wherein the set comprises at least two reflective facets.   The reflective facet of the plurality of sets of reflective facets is substantially linear, and a first reflective facet of the set of reflective facets is disposed at a first angle with respect to the optical axis, and reflective The second reflective facet of the set of facets is disposed at a second angle with respect to the optical axis, and the magnitude of the first angle is different from the magnitude of the second angle. apparatus.   The apparatus of claim 8, wherein different reflective facets in at least one of the collections of reflective facets have different lengths.   9. The apparatus of claim 8, wherein the base angles of different reflective facets in at least one of the sets are selected to form a desired average reflection angle for the set of reflective facets.   The apparatus of claim 8, wherein the different reflective facets in the at least one set of reflective facets have a base angle in the range of 2 ° to 20 °.   The apparatus of claim 11, wherein the base angle is in the range of 6 ° to 10 °.   The apparatus of claim 7, wherein at least one of the reflective facets is a non-linear facet.   The apparatus of claim 13, wherein at least one of the reflective facets is curved.   The apparatus of claim 13, wherein at least one of the reflective facets has at least two straight segments.   The apparatus of claim 1, wherein the structured reflector defines a reflective portion that is perpendicular to a normal to the display unit and a reflective portion that is not normal to a normal to the display unit.   17. The apparatus of claim 16, wherein the structured reflector comprises a reflective surface having a collection of reflective portions at a range of angles about a position perpendicular to a normal to the display unit.   The structured transflector primarily reflects image light on one side of the glare light when the device is illuminated by ambient light and the display unit reflects glare light resulting from the ambient light. Item 2. The apparatus according to Item 1.   The structured transflector reflects image light substantially surrounding the glare light when the device is illuminated by ambient light and the display unit reflects glare light resulting from the ambient light. The apparatus according to 1.   The apparatus of claim 1, wherein the structured dielectric reflector is disposed on a holographic surface.   The apparatus of claim 1, wherein the structured transflector further comprises a planarizing layer disposed on the dielectric reflector and facing the transmissive display unit.   The apparatus of claim 21, wherein the planarization layer comprises diffusing particles.   The apparatus of claim 21, wherein the planarization layer is an adhesive layer that bonds the structured transflector to the transmissive display unit.   24. The apparatus of claim 23, further comprising light diffusing particles provided in the adhesive layer.   The apparatus of claim 1, further comprising a diffuser disposed between the structured transflector and the transmissive display unit.   Since the structured transflector is generally in the xy plane and the structured reflector has an inclined surface that is inclined with respect to the xy plane, the xy plane in a direction parallel to the z-axis. The apparatus of claim 1, wherein light normally incident on is reflected by the inclined surface in a direction having a component in the yz plane.   27. The apparatus of claim 26, wherein at least one of the inclined surfaces is formed to reflect a portion of the incident light laterally so as to have a directional component in the x direction.   28. The apparatus of claim 27, wherein at least one of the inclined surfaces is curved to laterally reflect a portion of the incident light so as to have a directional component in the x direction.   28. The apparatus of claim 27, wherein at least one of the inclined surfaces has a surface that randomly varies to reflect a portion of the incident light laterally so as to have a directional component in the x-direction.   The apparatus according to claim 1, wherein the structured reflector includes a set of inclined surfaces, and the set of inclined surfaces corresponds to each pixel of the transmissive display unit.   32. The apparatus of claim 30, wherein different inclined surfaces in the set of inclined surfaces have different pitches.   The apparatus of claim 1, wherein the structured dielectric reflector comprises a substrate comprising a material having a relatively low refractive index and a partial reflector layer disposed on a structural surface of the substrate.   35. The apparatus of claim 32, wherein the partial reflector layer comprises a single layer of material having a refractive index higher than that of the substrate.   33. The apparatus of claim 32, wherein the partial reflector layer comprises a plurality of dielectric layers of relatively low refractive index and relatively high refractive index that are interleaved.   33. The apparatus of claim 32, further comprising a planarization layer on the partial reflector layer.   The substrate has a refractive index in the range of about 1.3 to about 1.8, and the dielectric reflector comprises at least one layer having a refractive index in the range of about 1.8 to 2.3. Item 33. The apparatus according to Item 32.   38. The apparatus of claim 36, wherein the surface of the dielectric reflector facing away from the substrate interacts with a medium having a refractive index in the range of 1 to about 1.8.   33. The apparatus of claim 32, wherein the planarization layer has a refractive index that is substantially the same as the refractive index of the substrate.   The apparatus of claim 1 wherein the structured dielectric reflector comprises a plurality of dielectric layers of alternating low and high refractive indices.   The apparatus of claim 1, wherein the structured dielectric reflector comprises a plurality of dielectric layers whose optical thickness is not an odd integer multiple of a quarter of a selected wavelength.   The at least one light manipulation film is directed to a first prism-like ridged brightness enhancement film having ridges oriented in a first direction, and a second direction perpendicular to the first direction. And a second prismatic ridged brightness enhancement film having a ridge formed thereon.   The apparatus of claim 1, further comprising a control unit coupled to the display unit to control an image displayed on the display unit. A structure comprising a color transmissive display unit having a viewing side and a back side, and a structured substrate disposed on the back side of the color display unit and having a structural surface and a dielectric partial reflector disposed on the structural surface A semi-transparent material,
A transflective display device in which ambient light incident on the display unit generates glare light in a glare direction, and the structured transflector reflects image light over a range that substantially surrounds the glare direction.   44. The apparatus of claim 43, wherein the dielectric partial reflector has a transmittance in the range of 70% to 90%.   44. The apparatus of claim 43, wherein the transmissive display unit is a liquid crystal display unit.   And further comprising a backlight unit for generating a backlight, wherein the structured transflector is disposed between the color display unit and the backlight unit, and the backlight passes through the structured transflector. 44. The apparatus of claim 43, wherein the apparatus reaches the color display unit.   47. The apparatus of claim 46, wherein the backlight unit comprises a light source and at least one light manipulation film disposed between the light source and the structured transflector.   The at least one light manipulation film is directed to a first prism-like ridged brightness enhancement film having ridges oriented in a first direction, and a second direction perpendicular to the first direction. 48. The apparatus of claim 47, comprising: a second prismatic ridged brightness enhancement film having a ridge.   47. The apparatus of claim 46, wherein light from the backlight passes through the structured translucent body in an input direction and exits the structured translucent body in a direction substantially parallel to the input direction.   44. The apparatus of claim 43, wherein the dielectric partial reflector defines a reflective portion that is perpendicular to a normal to the display unit and a reflective portion that is not perpendicular to the normal to the display unit.   51. The apparatus of claim 50, wherein the dielectric reflector comprises a reflective surface having a collection of reflective portions at a range of angles about a position that is perpendicular to a normal to the display unit.   44. The apparatus of claim 43, wherein the structured transflector further comprises a planarization layer disposed on the dielectric reflector and facing the transmissive display unit.   53. The apparatus of claim 52, wherein the planarization layer comprises diffusing particles.   53. The apparatus of claim 52, wherein the planarizing layer is an adhesive layer that bonds the structured transflector to the transmissive display unit.   The apparatus of claim 1, further comprising a diffuser disposed between the structured transflector and the transmissive display unit.   The structured reflector comprises a plurality of reflecting units, each reflecting unit comprises a set of reflecting portions at positive and negative angles with respect to an axis passing through the structured reflector, and the display unit comprises pixels. 44. The apparatus of claim 43, wherein each pixel of the display unit is disposed on a collection of two or more reflective units.   44. The substrate of claim 43, wherein the substrate has a relatively low refractive index, and the dielectric partial reflector comprises a single layer of a relatively high refractive index material disposed on the structural surface of the substrate. apparatus.   44. The apparatus of claim 43, wherein the partial reflector layer comprises a plurality of dielectric layers of relatively low refractive index and relatively high refractive index that are interleaved.   59. The apparatus of claim 58, wherein the dielectric layer has an optical thickness that is not an odd integer multiple of one quarter of a selected wavelength.   44. The apparatus of claim 43, further comprising a planarization layer on the dielectric partial reflector layer.   61. The device of claim 60, wherein the planarization layer has a refractive index that is substantially the same as the refractive index of the substrate.   The substrate has a refractive index in the range of about 1.3 to about 1.8, and the dielectric partial reflector comprises at least one layer having a refractive index in the range of about 1.8 to 2.3; 44. The apparatus of claim 43.   68. The surface of the dielectric partial reflector facing in a direction different from the structural surface of the substrate interacts with a medium having a refractive index in the range of 1 to about 1.8. apparatus.   44. The apparatus of claim 43, further comprising a control unit coupled to the display unit to control images displayed on the display unit.

Images