Dual function electro-optical display device exhibiting a bistable image or a fugitive image depending the applied voltage
First Claim
1. A dual function electro-optical display device, comprising:
- a liquid crystal medium having at least two possible light modulating modes, a first nematic mode being responsive to a first voltage to form a fugitive image, and a second cholesteric mode being responsive to a second voltage to form a persistent image.
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Accused Products
Abstract
A dual function electro-optical display device operates as a bistable display when driven at one voltage, and operates as a nematic display when driven at another voltage. In the first mode, the image in the display zone is formed by applying a first electrical signal to the device, and the image persists upon removal of the first electrical field. In the second mode, the image is formed by applying a second electrical signal to the device, and the image disappears upon removal of the second electrical signal. In a liquid crystal display, the liquid crystal fluid (9) is a blend of at least one liquid crystal nematic compound and at least one liquid crystal cholesteric compounds, and is maintained in a gap (4) between two substrates (1).
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Citations
24 Claims
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1. A dual function electro-optical display device, comprising:
a liquid crystal medium having at least two possible light modulating modes, a first nematic mode being responsive to a first voltage to form a fugitive image, and a second cholesteric mode being responsive to a second voltage to form a persistent image. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A dual function liquid crystal display, comprising:
a liquid crystal display that exhibits the characteristic of being operable as a bistable display when driven at a first voltage, and operable as a nematic display when driven at a second voltage. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A dual function liquid crystal display, comprising:
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a liquid crystal display having a liquid crystal medium comprising a mixture of between 90-99.7% of a nematic liquid crystal material and between 0.3-10% of a cholesteric liquid crystal material; and said liquid crystal display exhibiting the characteristic of being operable as a bistable display when driven at a voltage in excess of 20 volts, and operable as a nematic display when driven at a voltage less than 15 volts.
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16. A dual function electro-optical display device, comprising:
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an electro-optical display device that provides an image; a first portion of said image formed by applying a first electrical field to the device, said first portion of said image persisting upon removal of said first electrical field; and a second portion of said image formed by applying a second electrical field to the device, said second portion of said image disappearing upon removal of said second electrical field. - View Dependent Claims (17, 18, 19, 20, 21)
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- 22. In an electro-optical display device including a first substrate having an optically transmissive and electrically conducting coating on a face thereof, a second substrate having an electrically conductive coating on a face thereof, said substrates being positioned such that the coatings are adjacent and substantially equidistantly spaced, a light source means positioned to direct light toward the substrates, a liquid crystal composition occupying a space between said coatings, and means for impressing a voltage between selected portions of said coatings, the display characterized by said liquid crystal composition exhibiting a nematic response to a first voltage of less than 10 volts to form a fugitive image which vanishes when the first voltage is removed, and exhibiting a bistable response to a second voltage of greater than 15 volts to form a persistent image which remains when the second voltage is removed.
Specification