Liquid crystal display with particular relationship of the capacitances

• US 4,838,653 A
• Filed: 03/18/1988
• Issued: 06/13/1989
• Est. Priority Date: 07/22/1986
• Status: Expired due to Term

• Current Assignee: Raychem Limited (TE Connectivity Limited)
• Original Assignee: Raychem Limited (TE Connectivity Limited)
• Inventors: Mohebban, Manoochehr
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Pellman, Anita E.
• Application Number:
  US07/197,771
• Time in Patent Office: 452 Days
• Field of Search: 350/335, 350/350 S, 350/332
• US Class Current: 349/199
• CPC Class Codes: G01R 1/06777 High voltage probes
• CPC Class Codes: G01R 15/245 using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement

Abstract

A display comprises an array of a plurality of liquid crystal elements electrically connected in series. The element with the lowest capacitance when energized comprises a liquid crystal material having a positive dielectric anisotropy so that it has a higher capacitance when energized than when non-energized. A second of the elements has a capacitance when non-energized lower than the capacitance of the first element when it is energized. The display can be used for detecting a voltage or an electric field.

Claims

1. A liquid crystal display comprising an array of a plurality of liquid crystal elements, said array comprising:

(a) a first liquid crystal element having a capacitance in the non-energized state lower than the capacitance of any other of said liquid crystal elements and comprising a liquid crystal material having a positive dielectric anisotropy so that said liquid crystal element has a capacitance in the energized state higher than its capacitance in the nonenergized state; and

(b) a second liquid crystal element connected electrically in series with said first liquid crystal element, said second liquid crystal element having a capacitance in the non-energized state lower than the capacitance of the first liquid crystal element in its energized state.

2. A liquid crystal display in accordance with claim 1, comprising an array of at least five liquid crystal elements, the elements being electrically connected in series.

3. A display in accordance with claim 2, wherein the liquid crystal elements comprise a liquid crystal material having a positive dielectric anisotropy.

4. A display in accordance with claim 3, wherein the liquid crystal material is smectic or nematic.

5. A display in accordance with claim 4, wherein the liquid crystal material is an encapsulated liquid crystal material.

6. A display in accordance with claim 2, wherein the liquid crystal elements are of substantially the same size.

7. A liquid crystal device comprising a plurality of liquid crystal arrays in accordance with claim 1, at least one of said arrays being connected in parallel to at least one other of said arrays.

8. A method of making a display comprising an array of a plurality of liquid crystal elements connected in series, said method comprising:

(a) providing first and second support members;

(b) providing said first support member with electrodes in a first predetermined pattern;

(c) providing said second support member with electrodes in a second predetermined pattern, said first and second patterns being such that when the support members are superimposed and aligned, the electrodes of said first support member partially overlap the electrodes of said second support member providing areas of overlap;

(d) positioning a layer of liquid crystal material having a positive dielectric anisotropy between said first and second support members;

(e) superimposing and aligning said support members such that their respective electrodes are facing said liquid crystal layer and the overlap areas of the electrodes with liquid crystal material therebetween form a plurality of liquid crystal elements connected in series by overlapping electrodes, said array having a first liquid crystal element having a capacitance in the non-energized state lower than the capacitance of any other liquid crystal element and a second liquid crystal element having a capacitance in the non-energized state lower than the capacitance of the first liquid crystal element in its energized state; and

(f) laminating the resulting structure.

9. A method of detecting the presence of an electric field in a given area, comprising positioning a liquid crystal display in said area and observing the optical state of said liquid crystal display;

said liquid crystal display comprising an array of a plurality of liquid crystal elements, said array comprising;

(a) a first liquid crystal element having a capacitance in the non-energized state lower than the capacitance of any other of said liquid crystal elements and comprising a liquid crystal material having a positive dielectric anisotropy so that said liquid crystal element has a capacitance in the energized state higher than its capacitance in the non-energized state; and

(b) a second liquid crystal element connected electrically in series with said first liquid crystal element, said second liquid crystal element having a capacitance in the non-energized state lower than the capacitance of the first liquid crystal element in its energized state.

10. A method of detecting a voltage which comprises ohmically connecting at least one lead of a voltage source to a display comprising an array of a plurality of liquid crystal elements, said array comprising:

(a) a first liquid crystal element having a capacitance in the non-energized state lower than the capacitance of any other of said liquid crystal elements and comprising a liquid crystal material having a positive dielectric anisotropy so that said liquid crystal element has a capacitance in the energized state higher than its capacitance in the non-energized state; and

(b) a second liquid crystal element connected electrically in series with said first liquid crystal element, said second liquid crystal element having a capacitance in the non-energized state lower than the capacitance of the first liquid crystal element in its energized state.