Front-lit liquid crystal display having brightness enhancing film with microridges which directs light through the display to a reflector
First Claim
Patent Images
1. A front-lit display system, comprising:
- a display comprised of a plurality of pixels having front and back major surfaces;
a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display, and wherein the ridges have a pitch greater than one ridge per pixel;
a reflector provided adjacent the back surface of the display; and
a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display.
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Abstract
A front-lit display, having a ridged transparent film thereon. The ridges on the film bend glancing light rays down into the display. The light rays are reflected by a reflector below the display, pass back through the display, and exit the film in a direction substantially normal to the display. Thus, the ridged film enhances the brightness of the display for a given light source.
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Citations
20 Claims
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1. A front-lit display system, comprising:
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a display comprised of a plurality of pixels having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display, and wherein the ridges have a pitch greater than one ridge per pixel; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display. - View Dependent Claims (2, 3, 4)
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5. A front-lit liquid crystal display, comprising:
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a liquid crystal display having front and back major surfaces and a plurality of pixels therebetween; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, the ridges having a height within the range of from about 5 μ
m to 20 μ
m, the distance between neighboring ridge peaks being within the range of from about 10 to 20 times as great as the height of the ridges, the ridges having a pitch of at least one ridge per pixel, wherein the smooth surface is adjacent the front surface of the display;a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display.
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6. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display; wherein the ridges are each comprised of a first face for accepting the light rays and a second face for reflecting the light rays down toward the display by total internal reflection, neighboring ridges being separated by a third face parallel to the smooth face of the film, and wherein the first face of each ridge forms an angle α
within the range of from about 70°
to 90°
with respect to the smooth surface of the film and the second face of each ridge forms an angle β
within the range of from about 40°
to 50°
with respect to the smooth surface of the film.
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7. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display;
a reflector provided adjacent the back surface of the display; anda light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display; wherein the ridges are each comprised of a first face for accepting the light rays and a second face for reflecting the light rays down toward the display by total internal reflection, neighboring ridges being adjacent each other, and wherein the first face of each ridge forms an angle α
within the range of from about 5°
to 20°
with respect to the smooth surface of the film and the second face of each ridge forms an angle β
within the range of from about 60°
to 90°
with respect to the smooth surface of the film. - View Dependent Claims (8)
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9. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display; wherein the ridges are each comprised of a first face for accepting the light rays and a second face for reflecting the light rays by total internal reflection, and wherein neighboring ridges are separated by a third face which is inclined at an angle within the range of from about 1°
to 3°
with respect to the smooth surface of the film so that the third face is angled toward the light source. - View Dependent Claims (10)
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11. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display, wherein the film has a plurality of parallel grooves therein parallel to the ridges, wherein a groove is provided adjacent each ridge on the side of the ridge opposite the light source. - View Dependent Claims (12)
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13. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display, wherein the ridges are within the range of from about 5 μ
m to 20 μ
m high and the distance between neighboring ridge peaks is within the range of from about 10 to 20 times as great as the heights of the ridges;a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display.
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14. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, the light source comprising a point light source and a light pipe, parallel to the ridges, having a plurality of notches on the side of the pipe opposite the display, wherein light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display. - View Dependent Claims (15, 16)
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17. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film, the light source comprising a point light source and a light pipe, parallel to the ridges, the light pipe decreasing in thickness along its length from the end nearer the point light source, the thickness being decreased by a plurality of steps provided in the side of the pipe opposite the display, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display.
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18. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; and a light source for directing light rays onto the film at an angle γ
of less than 5°
with respect to the smooth surface of the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display. - View Dependent Claims (19)
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20. A front-lit display system, comprising:
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a display having front and back major surfaces; a transparent film having two major opposing surfaces, one smooth and the other having a plurality of parallel ridges, wherein the smooth surface is adjacent the front surface of the display; a reflector provided adjacent the back surface of the display; a first light source for directing light rays onto the film, wherein the light rays enter the film via the ridges, are reflected down through the film by total internal reflection, pass through the display, are reflected by the reflector, pass back through the display, and exit the film, whereby the film enhances the brightness of the display; and a second light source, similar to the first light source, provided on an end of the display opposite from the first light source, for directing light rays onto the film, wherein a first face of each ridge forms an angle α
with respect to the smooth surface of the film and second face of each ridge forms an angle β
with respect to the smooth surface of the film, wherein α
=β
.
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Specification