LCD with reduced canopy reflection having a retarder of 220-320 nm retardation outside a polarizer
First Claim
1. A liquid crystal display for providing an image to a viewer, the display comprising:
- a liquid crystal layer adjacent at least one electrode, said electrode for selectively applying a voltage across said liquid crystal layer;
front and rear linear polarizers sandwiching said liquid crystal layer therebetween, said front polarizer adapted to be positioned closest to the viewer; and
a retarder disposed adjacent said front polarizer so that said front polarizer is located between said liquid crystal layer and said retarder, and wherein said retarder has a retardation value of from about 220 to 320 nm so as to reduce image reflections off of an external medium.
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Accused Products
Abstract
A liquid crystal display and corresponding method are provided for reducing display image reflections off of a reflection point on an external medium (e.g. cockpit canopy or automotive windshield). A retarder is provided on the front side of the display so that the polarization direction of the display image is substantially parallel to the plane of incidence when the image reaches the reflection point. Additionally, the angle of incidence Θi is substantially matched to the Brewster angle ΘP in order to maximize the reduction of reflection at the reflection point. The retarder has a retardation value of from about 220-320 nm according to certain embodiments, and is a 1/2λ retarder according to preferred embodiments.
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Citations
18 Claims
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1. A liquid crystal display for providing an image to a viewer, the display comprising:
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a liquid crystal layer adjacent at least one electrode, said electrode for selectively applying a voltage across said liquid crystal layer; front and rear linear polarizers sandwiching said liquid crystal layer therebetween, said front polarizer adapted to be positioned closest to the viewer; and a retarder disposed adjacent said front polarizer so that said front polarizer is located between said liquid crystal layer and said retarder, and wherein said retarder has a retardation value of from about 220 to 320 nm so as to reduce image reflections off of an external medium. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A liquid crystal display for reducing image reflection at a reflection point on an exterior medium, the display comprising:
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a front polarizer having a transmission axis; a liquid crystal layer; and a retarder disposed adjacent said front polarizer so that said front polarizer is located between said retarder and said liquid crystal layer, said retarder having a retardation axis angularly arranged so that it substantially bisects the angle defined between the transmission axis of the front polarizer and a direction defined in a plane of incidence so as to reduce image reflection off of the exterior medium at the reflection point, wherein the plane of incidence is defined by the incident direction and a direction normal to the medium surface at the reflection point. - View Dependent Claims (9, 10, 11)
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12. A method of reducing liquid crystal display image reflections off of a reflection point on an external medium, the method comprising the steps of:
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providing a liquid crystal display having a retarder disposed adjacent the front polarizer so that said front polarizer is located between said retarder and a liquid crystal layer; causing an image to be emitted from the display in an incident direction toward the reflection point; and retarding the image using the retarder so that the image has a polarization direction substantially parallel to an incident plane when the image reaches the reflection point on the medium, the incident plane being defined by the incident direction and a direction normal to the medium surface at the reflection point, wherein the incident plane is defined by the incident direction and a direction normal to the medium surface at the reflection point. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of reducing liquid crystal display image reflections off of the canopy of an air vehicle, the method comprising the steps of:
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providing a liquid crystal display in a cockpit of the air vehicle; causing the display to emit an image toward a reflection point on the canopy, the canopy having an index of refraction of about 1.5; arranging the display so that the angle of incidence of the image on the canopy at the reflection point is about 56°
; andretarding the image after it leaves the display but before it reaches the reflection point on the canopy so that the polarization direction of the image when it reaches the reflection point on the canopy is approximately parallel to the plane of incidence thereby substantially reducing image reflection off of the canopy at the reflection point and permitting a substantial portion of the image to be transmitted through the canopy.
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Specification