Polymer-dispersed liquid crystal composition and liquid crystal display elements using the composition

• US 6,211,931 B1
• Filed: 01/27/1999
• Issued: 04/03/2001
• Est. Priority Date: 01/27/1998
• Status: Expired due to Fees

• Current Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Original Assignee: Hitachi Maxell Limited (Maxell, Ltd.)
• Inventors: Yamashita, Yuji, Ooae, Kouji, Fukao, Ryuzo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/238,069
• Time in Patent Office: 797 Days
• Field of Search: 349/86, 349/89, 349/74
• US Class Current: 349/86
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 2202/04 dye

Abstract

The object of the present invention is to provide a polymer-dispersed liquid crystal display element which won'"'"'t cause cross-talk effects and is capable of simple matrix drive. In the polymer-dispersed liquid crystal display element of the present invention, a polymer having a dielectric constant greater than that of the liquid crystal is used, and the volumetric content of the liquid crystal is not greater than that of the polymer.

Claims

1. A polymer-dispersed liquid crystal composition comprising a blend of at least a polymer and liquid crystal, wherein the volumetric content of the liquid crystal is not greater than that of the polymer and the polymer comprises a cyanoethylated compound having a greater dielectric constant than that of the liquid crystal.

2. The polymer-dispersed liquid crystal composition according to claim 1, wherein the content of the polymer is in the range of 50 to 99 vol % and the content of the liquid crystal is in the range of 50 to 1 vol %.

3. The polymer-dispersed liquid crystal composition according to claim 2, wherein the content of the polymer is in the range of 70 to 95 vol % and the content of the liquid crystal is in the range of 30 to 5 vol %.

4. The polymer-dispersed liquid crystal composition according to claim 3, wherein the content of the polymer is 85 vol % and the content of the liquid crystal is 15 vol %.

5. The polymer-dispersed liquid crystal composition according to claim 1, further comprising a dichroic dye.

6. The polymer-dispersed liquid crystal composition according to claim 1, wherein the compound is at least one selected from the group consisting of cyanoethylated cellulose, cyanoethylated pullulan, cyanoethylated saccharose and cyanoethylated polyvinyl alcohol.

7. A liquid crystal display element capable of simple matrix drive, said display element comprising a transparent substrate having its inner side coated with a transparent electrode-constituting electroconductive film, a transparent or opaque substrate having its inner side coated with a transparent or opaque electrode-constituting electroconductive film, and a polymer-dispersed liquid crystal layer interposed between the electrode-constituting electroconductive film of the respective substrates, said liquid crystal being mostly aligned in the direction vertical to the electrode-constituting electroconductive film surface when a voltage is applied thereto, and being mostly aligned in the direction non-vertical to the electrode-constituting electroconductive film surface when no voltage is aplied thereto, said polymer comprises a cyanoethylated compound having a greater dielectric constant than that of the liquid crystal, wherein the volumetric content of the liquid crystal in the polymer dispersed liquid crystal layer is not greater than the volumetric content of the polymer.

8. The liquid crystal display element according to claim 7, wherein the content of the polymer in the polymer-dispersed liquid crystal layer is in the range of 50 to 99 vol % and the content of the liquid crystal is in the range of 50 to 1 vol %.

9. The liquid crystal display element according to claim 8, wherein the content of the polymer in the polymer-dispersed liquid crystal layer is in the range of 70 to 95 vol % and the content of the liquid crystal is in the range of 30 to 5 vol %.

10. The liquid crystal display element according to claim 9, wherein the content of the polymer is 85 vol % and the content of the liquid crystal is 15 vol %.

11. The liquid crystal display element according to claim 7, wherein the polymer-dispersed liquid crystal layer further contains a dichroic dye.

12. The liquid crystal display element according to claim 7, which is a matrix type element.

13. The liquid crystal display element according to claim 7, wherein the compound is at least one selected from the group consisting of cyanoethylated cellulose, cyanoethylated pullulan, cyanoethylated saccharose and cyanoethylated polyvinyl alcohol.

14. A liquid crystal display element comprising a first transparent or opaque substrate having on one side thereof a first transparent or opaque electroconductive film, a second transparent substrate having on one side thereof a second transparent electroconductive film and on the other side a third transparent electroconductive film, a third transparent substrate having on one side thereof a fourth transparent electroconductive film, a first polymer-dispersed liquid crystal layer interposed between said first transparent or opaque electroconductive film and said second transparent electroconductive film, and a second polymer-dispersed liquid crystal layer interposed between said third transparent electroconductive film and said fourth transparent electroconductive film, wherein said first transparent or opaque electroconductive film and said fourth transparent electroconductive film constitute a first electrode, and said second transparent electroconductive film and said third transparent electroconductive film constitute a second electrode, and further characterized in that the volumetric content of the liquid crystal in the polymer-dispersed liquid crystal layer is not greater than the volumetric content of the polymer,

wherein the content of the polymer is 85 vol % and the content of the liquid crystal is 15 vol %.

15. A process for producing a liquid crystal display element comprising a first substrate having on one side thereof a first electroconductive film, a second substrate having on one side thereof a second electroconductive film, and a liquid crystal layer disposed between said first and second electroconductive films, the process comprising the steps of:

coating a polymer-dispersed liquid crystal composition on the first electroconductive film of the first substrate to form a polymer-dispersed liquid crystal layer;

coating a polymer solution on the second electroconductive film of the second substrate to form a polymer monolayer; and

disposing the polymer-dispersed liquid crystal layer of the first substrate vis-à

-vis the polymer monolayer of the second substrate, and bonding the first and second substrates to each other,

wherein the content of the polymer in the polymer-dispersed liquid crystal composition is 85 vol % and the content of the liquid crystal is 15 vol %.