HIGH-BRIGHTNESSS COLOR LIQUID CRYSTAL DISPLAY PANEL EMPLOYING LIGHT RECYCLING THEREIN
First Claim
1. A reflective cholesteric liquid crystal color filter comprising:
- a first layer of reflective cholesteric liquid crystal color filters of one handedness having at least a first light reflecting portion reflecting a first bandwidth around a first center wavelength and a second light reflecting portion reflecting a second bandwidth around a second center wavelength and, a second layer of reflective cholesteric liquid crystal color filters of the same handedness as the first layer having at least a third light reflecting portion reflecting a third bandwidth around a third center wavelength, and a fourth light reflecting portion reflecting a forth bandwidth around a forth center wavelength, the second layer of reflective cholesteric liquid crystal color filters adjacent the first layer of reflective cholesteric liquid crystal color filters such that adjacent first and second layer reflecting portions reflect different wavelengths of incident light of the same handedness and transmit the remaining wavelengths.
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Accused Products
Abstract
Reflective color filters using layers of cholesteric liquid crystals with two different center wavelengths and bandwidths per layer are stacked in two layers to provide colored light for displays. With a two layer stack circularly polarized light of one handedness can be provided. With a four layer stack unpolarized colored light can be provided. With a broadband polarizing filter overlapping other filters in the stack a black matrix can be provided by reflecting all colors and transmitting no light in the overlapping areas. When broadband reflective cholesteric liquid crystals are used two primary colors can be reflected in the same pixel of a display making reflective layers with two reflective portions per layer possible. Color displays having three linear sub-pixels with three primary colors or with four sub-pixels of white, blue, green, and red in a pixel with two colors in a top row and two colors on a bottom row can are made with two colors per layer in two layer stacks. The pixels in the display are arranged such that multiple adjacent sub-pixels in a layer, or row in a layer, with the same color makes the color filters easier to manufacture. Displays using these reflective color filters may have a reflective polarizer for viewing the display at wide angles without color distortion.
A method of producing cholesteric liquid crystal color filters by polymerizing different portions of cholesteric liquid crystal mixtures at different temperatures and radiations to obtain different central wavelengths and bandwidths of reflection. By masking parts of a layer several portions with different colors are polymerized in a single layer. Further, with radiation which is attenuated in the cholesteric liquid crystal material stacks of different portions reflecting different colors in the same layer are made. Further the cholesteric liquid crystals are polymerized to have other optical properties in the stack such as quarter wave plates and broad band polarizers such that entire optical devices can be made in one layer of cholesteric liquid crystal material making the devices smaller, lighter, more robust, reliable, and easier to make by eliminating gluing and alignment problems. With overlapping reflective cholesteric liquid crystal which together reflect all light stacks with automatic black matrixes built into the layer are made saving light from being blocked by conventional black matrix light absorbing layers in display devices.
51 Citations
146 Claims
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1. A reflective cholesteric liquid crystal color filter comprising:
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a first layer of reflective cholesteric liquid crystal color filters of one handedness having at least a first light reflecting portion reflecting a first bandwidth around a first center wavelength and a second light reflecting portion reflecting a second bandwidth around a second center wavelength and, a second layer of reflective cholesteric liquid crystal color filters of the same handedness as the first layer having at least a third light reflecting portion reflecting a third bandwidth around a third center wavelength, and a fourth light reflecting portion reflecting a forth bandwidth around a forth center wavelength, the second layer of reflective cholesteric liquid crystal color filters adjacent the first layer of reflective cholesteric liquid crystal color filters such that adjacent first and second layer reflecting portions reflect different wavelengths of incident light of the same handedness and transmit the remaining wavelengths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76)
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38. A reflective cholesteric liquid crystal color filter manufacturing process comprising:
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mixing a cholesteric liquid crystal material subject to polymerization by exposure to a specific frequency ultraviolet light at a specific temperature for a specific time to yield a specific color band of reflection from a pitch gradient in the cholesteric liquid crystal when polymerized, degassing the mixture at approximately 90°
C. in a vacuum,sandwiching the mixture of cholesteric liquid crystal material between a top substrate and a bottom substrate, partially masking one of the substrates to block UV light passing therethrough to prevent polymerization of the mixture of cholesteric liquid crystal material in the masked portion, setting the temperature of the mixture of cholesteric liquid crystal material to a first specific temperature, exposing the unmasked mixture of cholesteric liquid crystal material to a first UV radiation for a first length of time which will polymerize the mixture of cholesteric liquid crystal material to reflect a first color of light in a first band width, unmasking the mixture of cholesteric liquid crystal material, setting the temperature of the mixture of cholesteric liquid crystal material to a second specific temperature, exposing the unmasked mixture of cholesteric liquid crystal material to a second UV radiation for a second length of time which will polymerize the mixture of cholesteric liquid crystal material to reflect a second color of light in a second band width to form a reflective cholesteric liquid color filter layer.
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77. An image display panel employing the recycling of light from a plurality of light reflective elements therewithin so as to produce color images with enhanced brightness for viewing by a viewer, said image display panel comprising:
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a backlighting structure including a light source for producing light consisting of spectral components having wavelengths over a substantial portion of the visible band of said electromagnetic spectrum, and a broad-band reflector for reflecting, within said backlighting structure, polarized light consisting of spectral components having wavelengths over a substantial portion of said visible band and, upon one or more reflections within said backlighting structure, converting the polarization state of said spectral components from a first polarization state (P1) to a second polarization state (P2) orthogonal to said first polarization state (P1), and from said second polarization state (P2) to said first polarization state (P1);
a plurality of pixel regions spatially encompassed within a predefined image display area definable relative to said backlighting structure, wherein each said pixel region spatially encompasses a plurality of subpixel regions and each said subpixel region within each said spatially-encompassing pixel region has a predefined spectral band over the visible band of the electromagnetic spectrum, each said subpixel region within each said pixel region having a light transmission portion and a light blocking portion, and each said light transmission portion and said light blocking portion having a frontside disposed in the direction of said viewer and a backside in the direction of said backlighting structure;
a broad-band reflective polarizer for reflecting light consisting substantially of spectral components having wavelengths over a substantial portion of said visible band and said first polarization state (PI), and transmitting a distribution of polarized light along a prespecified direction, substantially confined within said predefined image display area, and consisting substantially of spectral components having wavelengths over a substantial portion of said visible band and said second polarization state (P2);
a spatial intensity modulation structure including an array of polarization modifying elements, each said polarization modifying element being spatially registered with one said subpixel region and selectively modifying the polarization state of polarized light transmitted therethrough in response to a subpixel drive signal provided to said polarization modifying element, and a broad-band polarizer, cooperating with said array of polarization modifying elements, so as to modulate the spatial intensity of said produced distribution of polarized light and thereby produce a dark-type or bright-type intensity level at each said subpixel region along said broad-band polarizer; and
a spectral filtering structure having a pixelated array of pass-band reflective-type spectral filtering elements for spectrally filtering said polarized light, each said pass-band reflective-type spectral filtering element being spatially registered with one said subpixel region and tuned to one said predefined spectral band for transmitting only the spectral components of said polarized light having wavelengths within said predefined spectral band of said subpixel region, and reflecting the spectral components of said produced polarized light having wavelengths outside said predefined spectral band of said subpixel region so as to produce a predefined color value at said subpixel region spatially-registered with said pass-band reflective-type spectral filtering element;
a pattern of broad-band reflector material, in spatial registration with the backside of said light blocking portions of said subpixel regions, for reflecting produced light at the light blocking portions of said subpixel regions;
a pattern of broad-band absorption material, in spatial registration with the frontside of said light blocking portions of said subpixel regions, for absorbing ambient light incident upon said light blocking portions of said subpixel regions;
wherein, the spectral components of polarized light that are transmitted through said broad-band reflective polarizer along said prespecified direction contribute to said distribution of polarized light;
wherein, the spectral components of polarized light that are not transmitted through said broad-band reflective polarizer along said prespecified direction are reflected off said broad-band reflective polarizer and transmitted back towards said broad-band reflector for reflection and/or polarization conversion within said backlighting structure and retransmission through said broad-band reflective polarizer so as to contribute to said distribution of polarized light;
wherein, the spectral components of said polarized light that are transmitted through the pass-band reflective-type spectral filtering element at each said subpixel region within each said spatially-encompassing pixel region produce said predefined color value at said subpixel region; and
wherein, the spectral components of said polarized light that are not transmitted through the pass-band reflective-type spectral filtering element at each said subpixel region within each said spatially-encompassing pixel region are reflected off said pass-band reflective-type spectral filtering element and transmitted back towards said backlighting structure for reflection and/or polarization conversion and retransmission towards the other said subpixel regions within said spatially-encompassing pixel region in said spectral filtering structure;
wherein, the spectral components of said produced polarized that fall incident on the light blocking portions of said subpixel regions are reflected off said pattern of broad-band reflector material disposed thereon, and transmitted back towards said backlighting structure for reflection and/or polarization conversion and retransmission towards the other said subpixel regions within said spatially-encompassing pixel region in said spectral filtering structure;
wherein, the spectral components of ambient light falling incident upon the light blocking portions of said subpixel regions are absorbed by said pattern of broad-band absorption material disposed thereon, thereby reducing glare from said image display panel due to ambient light incident thereon;
whereby said color images are produced from said predefined image display area having enhanced brightness. - View Dependent Claims (78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 115)
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96. A liquid crystal display (LCD) panel construction for producing color images for viewing by a viewer, said LCD panel construction comprising:
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a plurality of pixel regions within a predefined image display area, wherein each said pixel region has a plurality of subpixel regions and each said subpixel region within each said pixel region has a light transmission portion and a light blocking portion, and each said light transmission portion and said light blocking portion having a frontside disposed in the direction of said viewer and a backside in the direction of said illumination means;
illumination means for illuminating said plurality of pixel regions from the backside thereof so that a color image is formed from said plurality of pixel regions for viewing;
a pattern of broad-band reflector material, in spatial registration with the backside of said light blocking portions of said subpixel regions, for reflecting produced light at structures associated with said light blocking portions of the subpixels and thereby recycling produced light for use in illuminating said plurality of pixel regions; and
a pattern of broad-band absorption material, in spatial registration with the frontside of said light blocking portions of said subpixel regions, for absorbing ambient light incident upon structures associated with said light blocking portions of said subpixels and thereby reducing glare at the surface of the LCD panel due to ambient light incident thereon.
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97. An image display panel employing the recycling of light from a plurality of light reflective elements therewithin so as to produce color images with enhanced brightness for viewing by a viewer, said image display panel comprising:
a backlighting structure including a light source for producing light consisting of spectral components having wavelengths over a substantial portion of the visible band of said electromagnetic spectrum, and a broad-band reflector for reflecting, within said backlighting structure, polarized light consisting of spectral components having wavelengths over a substantial portion of said visible band and, upon one or more reflections within said backlighting structure, converting the polarization state of said spectral components from a first polarization state (P1) to a second polarization state (P2) orthogonal to said first polarization state (PI), and from said second polarization state (P2) to said first polarization state (P1);
a plurality of pixel regions spatially encompassed within a predefined image display area definable relative to said backlighting structure, wherein each said pixel region spatially encompasses a plurality of subpixel regions and each said subpixel region within each said spatially-encompassing pixel region has a predefined spectral band over the visible band of the electromagnetic spectrum, each said subpixel region within each said pixel region having a light transmission portion and a light blocking portion, and each said light transmission portion and said light blocking portion having a frontside disposed in the direction of said viewer and a backside in the direction of said backlighting structure;
a broad-band reflective polarizer for reflecting light consisting substantially of spectral components having wavelengths over a substantial portion of said visible band and said first polarization state (P1), and transmitting a distribution of polarized light along a prespecified direction, substantially confined within said predefined image display area, and consisting substantially of spectral components having wavelengths over a substantial portion of said visible band and said second polarization state (P2);
a spatial intensity modulation structure including an array of polarization modifying elements, each said polarization modifying element being spatially registered with one said subpixel region and selectively modifying the polarization state of polarized light transmitted therethrough in response to a subpixel drive signal provided to said polarization modifying element, and a broad-band polarizer, cooperating with said array of polarization modifying elements, so as to modulate the spatial intensity of said produced distribution of polarized light and thereby produce a dark-type or bright-type intensity level at each said subpixel region along said broad-band polarizer; and
a spectral filtering structure having a pixelated array of pass-band reflective-type spectral filtering elements for spectrally filtering said polarized light, each said pass-band reflective-type spectral filtering element being spatially registered with one said subpixel region and tuned to one said predefined spectral band for transmitting only the spectral components of said polarized light having wavelengths within said predefined spectral band of said subpixel region, and reflecting the spectral components of said produced polarized light having wavelengths outside said predefined spectral band of said subpixel region so as to produce a predefined color value at said subpixel region spatially-registered with said pass-band reflective-type spectral filtering element;
a pattern of broad-band reflector material, in spatial registration with the backside of said light blocking portions of said subpixel regions, for reflecting produced light at the light blocking portions of said subpixel regions;
a pattern of broad-band absorption material, in spatial registration with the frontside of said light blocking portions of said subpixel regions, for absorbing ambient light incident upon said light blocking portions of said subpixel regions;
wherein, the spectral components of polarized light that are transmitted through said broad-band reflective polarizer along said prespecified direction contribute to said distribution of polarized light;
wherein, the spectral components of polarized light that are not transmitted through said broad-band reflective polarizer along said prespecified direction are reflected off said broad-band reflective polarizer and transmitted back towards said broad-band reflector for reflection and/or polarization conversion within said backlighting structure and retransmission through said broad-band reflective polarizer so as to contribute to said distribution of polarized light;
wherein, the spectral components of said polarized light that are transmitted through the pass-band reflective-type spectral filtering element at each said subpixel region within each said spatially-encompassing pixel region produce said predefined color value at said subpixel region; and
wherein, the spectral components of said polarized light that are not transmitted through the pass-band reflective-type spectral filtering element at each said subpixel region within each said spatially-encompassing pixel region are reflected off said pass-band reflective-type spectral filtering element and transmitted back towards said backlighting structure for reflection and/or polarization conversion and retransmission towards the other said subpixel regions within said spatially-encompassing pixel region in said spectral filtering structure;
wherein, the spectral components of said produced polarized that fall incident on the light blocking portions of said subpixel regions are reflected off said pattern of broad-band reflector material disposed thereon, and transmitted back towards said backlighting structure for reflection and/or polarization conversion and retransmission towards the other said subpixel regions within said spatially-encompassing pixel region in said spectral filtering structure;
wherein, the spectral components of ambient light falling incident upon the light blocking portions of said subpixel regions are absorbed by said pattern of broad-band absorption material disposed thereon, thereby reducing glare from said image display panel due to ambient light incident thereon;
whereby said color images are produced from said predefined image display area having enhanced brightness. - View Dependent Claims (98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 117, 118, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146)
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116. A wide incident angle reflective broadband polarizer comprising:
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a first varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broad band of wavelengths, a first constant pitch helix cholesteric liquid crystal film for rotating the elliptical axis of light from the first varying pitch helix cholesteric liquid crystal film, adjacent the first varying pitch helix cholesteric liquid crystal film, a first homeotropic film for compensating the phase of the light from the first constant pitch helix cholesteric liquid crystal film, adjacent the first constant pitch helix cholesteric liquid crystal film such that unpolarized light entering the first varying pitch helix cholesteric liquid crystal film exits the first homeotropic film as circularly polarized light of one handedness for small and large angles of incidence.
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Specification