Ferroelectric liquid crystal optical modulation device with regions within pixels to initiate nucleation and inversion

• US 4,796,980 A
• Filed: 03/27/1987
• Issued: 01/10/1989
• Est. Priority Date: 04/02/1986
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kaneko, Shuzo, Kanbe, Junichiro, Toyono, Tsutomu
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Gallivan, Richard F.
• Application Number:
  US07/030,569
• Time in Patent Office: 655 Days
• Field of Search: 350/333, 350/334, 350/341, 350/350 S
• US Class Current: 349/85
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133753 with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
• CPC Class Codes: G02F 1/141 using ferroelectric liquid crystals
• CPC Class Codes: G02F 2203/30 Gray scale
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/207 by domain size control G09G3/3637 takes precedence
• CPC Class Codes: G09G 3/3637 with intermediate tones displayed by domain size control domain size control in flat matrix panels other than liquid crystal displays having memory effects G09G3/207

Abstract

An optical modulation device comprises a pair of substrates respectively having electrodes thereon arranged so as to form a pixel at an intersection thereof, and an optical modulation material disposed at the pixel. The pixel has regions of the optical modulation material having mutually different threshold characteristics.

Claims

1. An optical modulation device, comprising:

a plurality of pixels arranged two-dimensionally, each pixel comprising a first electrode and a second electrode disposed opposite to each other and an optical modulation material disposed between the first and second electrodes;

each pixel having regions with mutually different uniaxial alignment control powers for aligning the optical modulation material.

2. A device according to claim 1, wherein said optical modulation material is a ferroelectric liquid crystal.

3. A device according to claim 2, wherein said ferroelectric liquid crystal is a chiral smectic liquid crystal.

4. A device according to claim 3, wherein said chiral smectic liquid crystal is formed in a layer thin enough to release its own helical structure under no electric field.

5. A device according to claim 1, wherein said regions of the pixel with different control powers correspond to different regions of an alignment control layer.

6. A device according to claim 5, wherein said alignment control layer comprises an organic polymer layer.

7. A device according to claim 1, wherein said plurality of pixels are arranged in a plurality of rows and a plurality of columns, each row of pixels are commonly connected to a scanning electrode, and each column of pixels are commonly connected to an information electrode;

the device further comprising means for applying to the information electrode a pulse signal depending on given gradation data.

8. A device according to claim 7, wherein said pulse signal has a pulse duration depending on given gradation data.

9. A device according to claim 7, wherein said pulse signal has a number of pulses depending on given gradation data.

10. A device according to claim 7, wherein said pulse signal has a peak value depending on given gradation data.

11. A device according to claim 7, wherein said pulse signal is applied after the optical modulation material in the pixel concerned has been oriented to one stable state.

12. A device according to claim 1, wherein said regions with mutually different alignment control powers comprise first alignment control power regions and a second alignment control power region, said first alignment control power regions being dispersely distributed in said second alignment control power region.

13. An optical modulation device comprising:

a plurality of pixels arranged two-dimensionally, each pixel comprising a first electrode and a second electrode disposed opposite to each other with an optical modulation material disposed between the first and second electrodes;

each pixel having portions capable of having a locally different electric field intensity distributed dispersely in the pixel when an electric field is applied between the first and second electrodes wherein said portions having a locally different electric field intensity correspond to portions of the optical modulation material generating nuclei for initiating modulation.

14. A device according to claim 13, wherein the portions of a locally different electric field intensity correspond to minute projections produced in the pixel.

15. A device according to claim 14, wherein the portions of a locally different electric field intensity correspond to low-resistivity portions formed on at least one of the first and second electrodes.

16. A device according to claim 13, wherein said electric field applied between the first and second electrodes is given by a pulse signal having a duration depending on given gradation data.

17. A device according to claim 13, wherein said electric field applied between the first and second electrodes is given by a pulse signal having a number of pulses depending on given gradation data.

18. A device according to claim 13;

wherein said electric field applied between the first and second electrodes is given by a pulse signal having a peak value depending on given gradation data.

19. A device according to claim 13, wherein said optical modulation material is a ferroelectric liquid crystal.

20. A device according to claim 19, wherein said ferroelectric liquid crystal is a chiral smectic liquid crystal.

21. A device according to claim 20, wherein said chiral smectic liquid crystal is formed in a layer thin enough to release its own helical structure under no electric field.