Variable color electrooptic display
First Claim
1. A method for creating selectable indicia of a first color and a second background color comprising the steps of:
- polarizing light emitted from a light source by means of a first polarizer;
phase retarding selected portions of the polarized light exiting the first polarizer by applying a transverse electric field to selected areas on a substantially transparent uniaxial ferroelectric ceramic plate disposed in optical series with the first polarizer, said selected areas defining said indicia;
polarizing the light which exits from the ferroelectric ceramic plate by means of a second polarizer; and
providing additional phase retardation to light which exits from the first polarizer before said light strikes the second polarizer to provide a color bias, the additional phase retardation controlling the background color of the display and the combination of said additional phase retardation and the selected phase retarded portions of light controlling the color of the indicia.
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Accused Products
Abstract
An electrooptic color display for displaying selectable indicia includes a ferroelectric ceramic element, such as a PLZT material, first and second polarizers on each side of the element, and a mechanism for selectively inducing a transverse electric field at selectable areas on the element, said areas corresponding to the indicia. The electric field can be produced by applying a voltage to transparent interleaved electrodes on one or both surfaces of the ceramic element. These areas produce spectrally selective phase retardation which causes the color of the indicia to be different from that of the background color. Preferably a separate retardation element which may be fixed, variable, or a combination of both, is disposed between the polarizers to provide a fixed color bias that determines the background color. This invention contemplates transmissive, reflective, and transflective color displays.
196 Citations
33 Claims
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1. A method for creating selectable indicia of a first color and a second background color comprising the steps of:
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polarizing light emitted from a light source by means of a first polarizer; phase retarding selected portions of the polarized light exiting the first polarizer by applying a transverse electric field to selected areas on a substantially transparent uniaxial ferroelectric ceramic plate disposed in optical series with the first polarizer, said selected areas defining said indicia; polarizing the light which exits from the ferroelectric ceramic plate by means of a second polarizer; and providing additional phase retardation to light which exits from the first polarizer before said light strikes the second polarizer to provide a color bias, the additional phase retardation controlling the background color of the display and the combination of said additional phase retardation and the selected phase retarded portions of light controlling the color of the indicia. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An electrooptic display having selectable indicia of a first color and a background of a second color different from the first color comprising:
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a first and second polarizer; a substantially transparent uniaxial ferroelectric ceramic element having a first and second surface, and disposed between said first and second polarizers; means in addition to said element disposed between said first and second polarizers for providing spectrally selective phase retardation; and means for selectively inducing an electrical field at selectable areas on at least one of the first and second surfaces of said element, said electric field being transverse to the optical axis of the display and having a magnitude sufficient to cause spectrally selective phase retardation, said areas defining the indicia to be displayed, the phase retardation provided by said means for providing spectrally selective phase retardation defines said second background color, the cumulative phase retardation due to said induced field and said means for providing spectrally selective phase retardation defining said first color of the indicia. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification