Electrical contacts for polymer dispersed liquid crystal films

• US 5,142,644 A
• Filed: 03/08/1991
• Issued: 08/25/1992
• Est. Priority Date: 03/08/1991
• Status: Expired due to Term

• Current Assignee: Brown University
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: VanSteenkiste, Thomas H., Vaz, Nuno A.
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/666,310
• Time in Patent Office: 536 Days
• Field of Search: 350/336, 350/331 R, 359/88
• US Class Current: 349/86
• CPC Class Codes: G02F 1/133365 Cells in which the active layer comprises a liquid crystalline polymer
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13452 Conductors connecting driver circuitry and terminals of panels

Abstract

An electrical contact for use with an optically responsive, polymer dispersed liquid crystal film is provided. The preferred electrical contact means consists of a pair of U-shaped, electrically conductive spring connectors. Each of these spring connectors is rigidly biased against corresponding transparent electrodes provided on each of the surrounding transparent substrates, so as to provide a compressive clamping force against the electrode. This ensures an intimate and complete electrical connection between each spring connector and each transparent electrode. The spring connector may be formed from any electrically conductive material which is sufficiently strong yet yielding and which is sufficiently anodic with respect to the electrode material, a preferred material being a suitable beryllium copper alloy when the electrodes are formed from a material such as indium-tin oxide. The preferred spring connector also provides redundant electrical contact between each electrode and itself, therefore, enabling its use in large area devices, such as window panels, wherein it is imperative that failure at a single point of electrical contact does not result in failure of the electrical connection.

Claims

1. An optically responsive polymer dispersed liquid crystal film comprising:

a pair of substrates, each having an electrode disposed thereon with a polymer matrix therebetween so that each of said electrodes contacts said polymer matrix, at least one of said substrates and its corresponding electrode being transparent, said polymer matrix having liquid crystal microdroplets dispersed therein; and

means for electrically contacting at least one of said electrically conductive transparent electrodes, said means being at least one electrically conductive, essentially U-shaped spring connector having a contact end and a U-shaped region with an arcuate region disposed contiguous with and between said contact end and said U-shaped region, said contact end of said spring connector being biased against a corresponding contact region of said electrode, so as to compressively clamp and electrically contact said electrode at said contact region.

2. An optically responsive polymer dispersed liquid crystal film as recited in claim 1 further comprising a first electrically conductive overlayer applied to said transparent electrode at said contact region, so as to contact said electrically conductive spring connector.

3. An optically responsive polymer dispersed liquid crystal film as recited in claim 2 wherein said electrically conductive overlayer is a silver paint.

4. An optically responsive polymer dispersed liquid crystal film as recited in claim 2 further comprising:

a second electrically conductive layer covering said spring connector at said contact region and a layer of adhesive covering said second electrically conductive layer.

5. An optically responsive polymer dispersed liquid crystal film as claimed in claim 4, wherein said second electrically conductive layer is a silver paint.

6. An optically responsive polymer dispersed liquid crystal film as recited in claim 1, wherein said spring connector has a plurality of said contact ends so as to provide redundant electrical contact at said contact region of said electrode.

7. An optically responsive polymer dispersed liquid crystal film as recited in claim 1, wherein said spring connector is formed from a beryllium copper alloy and said electrodes are formed from indium-tin oxide.

8. An optically responsive polymer dispersed liquid crystal film comprising:

a pair of transparent substrates with a polymer matrix therebetween, said polymer matrix having liquid crystal microdroplets dispersed therein, each of said transparent substrates having an electrically conductive transparent electrode disposed thereon so that each of said electrodes contacts said polymer matrix;

a first electrically conductive overlayer applied to a contact region on each of said transparent electrodes; and

electrically conductive means for electrically contacting said transparent electrodes, said electrically conductive means being a pair of U-shaped, electrically conductive spring connectors each having a contact end and U-shaped region with an arcuate region disposed contiguous with and between said contact end and said U-shaped region, said contact end of each of said spring connectors being biased against said corresponding contact region of each of said electrodes so as to compressively clamp and electrically contact said electrically conductive overlayer at said contact region.

9. An optically responsive polymer dispersed liquid crystal film as recited in claim 8, wherein said first electrically conductive overlayer is a silver paint.

10. An optically responsive polymer dispersed liquid crystal film as recited in claim 8, wherein each of said spring connectors has a plurality of contact ends so as to provide redundant electrical contact at said contact region of each of said electrodes.

11. An optically responsive polymer dispersed liquid crystal film as recited in claim 8, wherein said spring connectors are formed from a beryllium copper alloy and said electrodes are formed from indium-tin oxide.

12. An optically responsive polymer dispersed liquid crystal film as recited in claim 8, further comprising:

a second electrically conductive layer covering said spring connector at said contact region, and a layer of adhesive covering said second electrically conductive layer.

13. An optically responsive polymer dispersed liquid crystal film as claimed in claim 12, wherein said second electrically conductive layer is a silver paint.

14. An optically responsive polymer dispersed liquid crystal film comprising:

a pair of transparent substrates with a polymer matrix therebetween, said polymer matrix having liquid crystal microdroplets dispersed therein, each of said transparent substrates having electrically conductive, transparent, indium-tin oxide electrodes disposed thereon so that each of said electrodes contacts said polymer matrix;

an electrically conductive, silver overlayer applied to a contact region on each of said transparent electrodes; and

a pair of U-shaped, electrically conductive spring connectors for electrically contacting said corresponding transparent electrodes, said U-shaped electrically conductive spring connectors being formed from a beryllium copper alloy and each of said U-shaped spring connectors having a plurality of projections extending from a corresponding U-shaped region, each of said projections having a contact end and an arcuate region which is contiguous with and between said contact end and said corresponding U-shaped region, each of said contact ends of each spring connector being biased against said corresponding contact region of said corresponding electrode so as to compressively clamp and redundantly electrically contact said electrically conductive overlayer at said contact region.

15. An optically responsive film as recited in claim 14 further comprising:

a second electrically conductive, silver layer covering each of said spring connectors at said contact regions, and a layer of adhesive covering said second electrically conductive layer.

16. An optically responsive film having a polymer matrix with liquid crystal microdroplets dispersed therein and a pair of transparent substrates surrounding the polymer matrix, each substrate having an electrically conductive, transparent indium-tin oxide electrode disposed thereon so that each of the electrodes contacts the polymer matrix;

wherein the improvement comprises;

a pair of U-shaped, electrically conductive spring connectors formed of a beryllium copper alloy, each of said spring connectors having a plurality of projections, each of said projections having a contact end and an arcuate region which is contiguous with and between said U-shaped region and said contact end, wherein each of said contact ends of each of said spring connectors is biased against a corresponding contact region on each of said electrodes so as to compressively clamp and redundantly electrically contact each of said electrodes at said contact ends.