Long life reflective liquid crystal display for dc operation

• US 4,128,312 A
• Filed: 10/04/1977
• Issued: 12/05/1978
• Est. Priority Date: 10/04/1977
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Little, Michael J., Lim, Hong S.
• Primary Examiner(s): Padgett, Benjamin R.
• Assistant Examiner(s): Gron, T. S.
• Application Number:
  US05/839,224
• Time in Patent Office: 427 Days
• Field of Search: 350/336, 350/338, 350/350, 252/299, 252/408
• US Class Current: 349/182
• CPC Class Codes: C09K 19/582 Electrically active dopants, e.g. charge transfer agents
• CPC Class Codes: G02F 1/1375 using dynamic scattering

Abstract

Reflective mode dynamic scattering displays are disclosed which operate under dc excitation for extremely long hours with excellent contrast. These displays are the results of a combination of a high reflectivity cathode, obtained by the use of silver mirror electrodes, with a redox doped ester liquid crystal in an otherwise conventional liquid crystal cell arrangement.

Claims

1. A reflective mode dynamic scattering display device capable of sustained operation when subjected to a dc current excitation comprising an electrode consisting of a transparent substrate coated with a thin layer of transparent conductor film selected from the group consisting of indium oxide, tin oxide and indium-tin oxide which functions as an anode, and a rigid substrate containing a silver mirror surface which surface functions as a cathode, maintained in a predetermined spaced relationship to said anode by spacers, the intermediate space containing a phenylbenzoate ester liquid crystal mixture doped with a redox dopant formed from mixtures of metallocenes and conjugated cyano-organic compounds which functions as an active electro-optic element in response to a dc current excitation.

2. The display device of claim 1 wherein said redox dopant is comprised of dibutylferrocene and 2,4,7,-trinitro-9-fluorenylidene)-malononitrile.

3. The display device of claim 2 wherein said phenylbenzoate ester liquid mixture is selected from the group consisting of 2N10, 2N12, 2N14 and 2N40 liquid crystal mixtures.

4. The display device of claim 2 wherein said liquid crystal mixture is comprised of 39.5% p-butylphenyl p-toluate, 13.2% p-butoxybenzoate, 23.7% p-butoxyphenyl p-hexyloxybenzoate and 23.7 p-butoxyphenyl p-octyloxybenzoate.

5. The claims of the display device of claim 2 wherein said phenylbenzoate mixture is comprised of 28.4% p-hexyloxyphenyl p-methoxybenzoate, 25.0% p-hexyloxyphenyl p-butoxybenzoate and 46.4% p-octyloxyphenyl p-hexyloxybenzoate.

6. A liquid crystal display device capable of sustained reflective mode dynamic scattering operations when subjected to a dc current excitation comprising a silver mirror cathode separated from a transparent anode comprising a thin layer of conductive film deposited on a transparent substrate by a phenylbenzoate liquid crystal mixture doped with a redox dopant formed from a mixture of metallocenes and conjugated cyano-organic compounds.

7. The display device of claim 6 wherein said liquid crystal mixture is a 2N10 mixture and said dopant comprises dibutylferrocene and (2,4,7,-trinitro-9-fluorenylidene)-malononitrile.

8. The display device of claim 6 wherein said conductive film is selected from the group consisting of indium oxide, indium-tin oxide and tin oxide.

9. A reflective mode dynamic scattering display device comprising a silver mirror cathode maintained in a predetermined spaced relationship to an anode comprised of a transparent substrate coated with a thin layer of transparent conductor film selected from the group consisting of indium oxide, tin oxide and indium-tin oxide by a phenylbenzoate ester liquid crystal mixture, doped with a redox dopant, formed from a mixture of metallocenes and conjugated cyano-organic compounds, which doped liquid crystal mixture functions as an active electro-optic element in response to dc current excitation, and spacers, for said electrodes, said display device being capable of sustained operation when subjected to said dc current excitation.