Layered superlattice ferroelectric liquid crystal display

• US 5,943,111 A
• Filed: 06/09/1998
• Issued: 08/24/1999
• Est. Priority Date: 06/09/1998
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation), Symetrix Corporation
• Original Assignee: Matsushita Electronics Corp (Panasonic Holdings Corporation), Symetrix Corporation
• Inventors: McMillan, Larry D.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Hollingshead, Robert J.
• Application Number:
  US09/094,086
• Time in Patent Office: 441 Days
• Field of Search: 349/171
• US Class Current: 349/171
• CPC Class Codes: G02F 1/133603 with LEDs

Abstract

A thin film of ferroelectric layered superlattice material in a flat panel display device is energized to selectively influence the display image. In one embodiment, a voltage pulse causes the layered superlattice material to emit electrons that impinge upon a phosphor, causing the phosphor to emit light. In another embodiment, an electric potential creates a remanent polarization in the layered superlattice material, which exerts an electric field in liquid crystal layer, thereby influencing the transmissivity of light through the liquid crystal. The layered superlattice material is a metal oxide formed using a special liquid precursor containing an alkoxycarboxylate. The thin film of layered superlattice material is formed using a spin-on technique and low-temperature heat treating. The thin film thickness is preferably in the range 500-1400 Å so that polarizability and transparency of the thin film is enhanced.

Claims

1. In an optical display device having an optical element that is selectively operable for optical effects by influence of a ferroelectric material, and a ferroelectric material located proximate said optical element for selective operation thereof, the improvement comprising:

said ferroelectric material being a layered superlattice material.

2. A display device as in claim 1 wherein said optical element comprises a luminescent material, said optical effect is the emission of light, and said layered superlattice material emits electrons that impinge upon said luminescent material to produce said optical effect.

3. A display device as in claim 2 comprising a thin film of said layered superlattice material with a thickness not exceeding 4000 Å

(300 nanometers).

4. A display device as in claim 2 comprising a thin film of said layered superlattice material with a thickness not exceeding 1400 Å

(140 nanometers).

5. A display device as in claim 1 wherein said optical element comprises a liquid crystal material, said optical effect is a change in transmissivity of light through said liquid crystal material, and said layered superlattice material exerts an electric field upon said liquid crystal material.

6. A display device as in claim 5 comprising a thin film of said layered superlattice material with a thickness not exceeding 4000 Å

(300 nanometers).

7. A display device as in claim 5 comprising a thin film of said layered superlattice material with a thickness not exceeding 1400 Å

(140 nanometers).

8. A display device as in claim 1 wherein said layered superlattice material comprises an excess amount of at least one of the elements selected from the group consisting of superlattice generator elements and B-site elements.

9. A display device as in claim 1 wherein said layered superlattice material comprises strontium bismuth tantalate, and at least one of the metals bismuth and tantalum is present in an excess amount.

10. A display device as in claim 1 wherein said layered superlattice material comprises strontium bismuth tantalum niobate, and at least one of the metals bismuth, tantalum and niobium is present in an excess amount.

11. A method for fabricating a ferroelectric device in an optical display comprising the steps of:

providing a substrate;

providing a precursor containing metal moieties in effective amounts for spontaneously forming a ferroelectric layered superlattice material upon drying and heating of said precursor;

applying said precursor to said substrate;

drying said precursor to form a dried material on said substrate;

heating said dried material at a temperature of between 500°

C. and 1000°

C. to yield a thin film of layered superlattice material containing said metal moieties on said substrate; and

completing said ferroelectric device.

12. A method as in claim 11 wherein said optical display comprises a luminescent material.

13. A method as in claim 12 wherein said thin film of layered superlattice material has a thickness not exceeding 4000 Å

(300 nanometers).

14. A method as in claim 12 wherein said thin film of layered superlattice material has a thickness not exceeding 1400 Å

(140 nanometers).

15. A method as in claim 11 wherein said ferroelectric device comprises a liquid crystal material.

16. A method as in claim 15 wherein said thin film of layered superlattice material has a thickness not exceeding 4000 Å

(300 nanometers).

17. A method as in claim 15 wherein said thin film of layered superlattice material has a thickness not exceeding 1400 Å

(140 nanometers).

18. A method as in claim 11 wherein said precursor comprises an excess amount of at least one of the elements selected from the group consisting of superlattice generator elements and B-site elements.

19. A method as in claim 11 wherein said precursor comprises metal moieties in effective amounts for forming strontium bismuth tantalate.

20. A method as in claim 19 wherein said precursor comprises excess amounts of at least one of bismuth and tantalum.

21. A method as in claim 11 wherein said precursor comprises metal moieties in effective amounts for forming strontium bismuth tantalum niobate.

22. A precursor as in claim 21 wherein said precursor comprises excess amounts of at least one of bismuth, tantalum and niobium.