Liquid crystal display with means for varying intensity of applied electric field

• US 6,111,626 A
• Filed: 10/09/1998
• Issued: 08/29/2000
• Est. Priority Date: 10/09/1997
• Status: Expired due to Term

• Current Assignee: NLT Technologies, Ltd.
• Original Assignee: NEC Corporation
• Inventors: Watanabe, Makoto, Watanabe, Takahiko
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US09/168,693
• Time in Patent Office: 690 Days
• Field of Search: 349/141, 349/78, 349/85, 349/138, 349/139, 349/191
• US Class Current: 349/141
• CPC Class Codes: G02F 1/133707 Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/136218 Shield electrodes

Abstract

A parallel field active matrix liquid crystal display comprising a means for varying the intensity of an applied electric field. The intensity of the applied electric field is varied by insulating film slits or electric field shield pixel electrodes. Insulating film slits are defined by removing an insulating film between electrode pairs, in any one or more of a plurality of pairs of electrodes including pixel electrodes and common electrodes within a unit pixel of a display pixel. Alternatively, electric field shield pixel electrodes for shielding part of an electric field are patterned in the same layer as pixel electrodes above several common electrodes of a plurality of pairs of electrodes including pixel electrodes and common electrodes within a unit pixel of a display pixel.

Claims

1. An active-matrix liquid crystal display device comprising:

a plurality of display pixels, scanning lines, and signal lines disposed on a first transparent substrate;

a liquid crystal orientation film disposed on said first transparent substrate either directly or through an insulating layer;

a liquid crystal orientation film disposed on a second transparent substrate disposed in opposed relation to said first transparent substrate;

a liquid crystal layer sandwiched between said first transparent substrate and said second transparent substrate;

means for varying a polarized state of incident light applied to said first transparent substrate based on an oriented state of said liquid crystal layer;

said display pixel comprising pixel electrodes, common electrodes, and an active element for applying an electric field to said liquid crystal layer substantially parallel to said first transparent substrate and said second transparent substrate; and

said display pixel being connected to external control means for controlling the applied electric field freely according to a display pattern;

wherein a distance between pairs of said pixel electrodes and said common electrodes, a width of said pixel electrodes, and a width of said common electrodes are constant; and

said active-matrix liquid crystal display device further comprising means for varying an intensity of the applied electric field during application of the applied electric field to said display pixels, application of said electric field to said display pixels being controlled by said external control means according to said display pattern.

2. An active-matrix liquid crystal display device according to claim 1, wherein said means for varying the intensity of the applied electric field comprises a field shield pixel electrode disposed above at least one of said common electrodes in said display pixel with an insulating layer interposed therebetween, for shielding part of an electric field generated by said common electrode, said field shield pixel electrode having a shape overlapping part of said common electrode.

3. A method of displaying an image on an active-matrix liquid crystal display device according to claim 2, comprising the step of varying the intensity of the applied electric field with the means for varying the intensity of the applied electric field.

4. A method of displaying an image on an active-matrix liquid crystal display device according to claim 1, comprising the step of varying the intensity of the applied electric field with the means for varying the intensity of the applied electric field.

5. An active-matrix liquid crystal display device according to claim 1, wherein said means for varying the intensity of the applied electric field comprises a first medium, disposed between a first common electrode and a first pixel electrode, and a second medium, disposed between a second common electrode and a second pixel electrode, in the display pixel, and

wherein said first medium is not identical to said second medium.

6. A method of displaying an image on an active-matrix liquid crystal display device according to claim 5, comprising the step of varying the intensity of the applied electric field with the means for varying the intensity of the applied electric field.

7. An active-matrix liquid crystal display device according to claim 1, wherein said means for varying the intensity of the applied field comprises a first medium, disposed between a first common electrode and a first pixel electrode, and a second medium, disposed between a second common electrode and said first pixel electrode, in the display pixel, and

wherein said first medium is not identical to said second medium.

8. A method of displaying an image on an active-matrix liquid crystal display device according to claim 7, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.

9. An active-matrix liquid crystal display device according to claim 1, wherein said means for varying the intensity of the applied field comprises a first medium, disposed between a first common electrode and a first pixel electrode, and a second medium, disposed between said first common electrode and a second pixel electrode, in the display pixel;

wherein said first medium is not identical to said second medium.

10. A method of displaying an image on an active-matrix liquid crystal display device according to claim 9, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.

11. An active-matrix liquid crystal display device comprising:

a plurality of display pixels, scanning lines, and signal lines disposed on a first transparent substrate;

a liquid crystal orientation film disposed on said first transparent substrate either directly or through an insulating layer;

a liquid crystal orientation film disposed on a second transparent substrate disposed in opposed relation to said first transparent substrate;

a liquid crystal layer sandwiched between said first transparent substrate and said second transparent substrate;

wherein a polarized state of incident light applied to said first transparent substrate is varied based on an oriented state of said liquid crystal layer,

said display pixel comprising pixel electrodes, common electrodes, and an active element for applying an electric field to said liquid crystal layer substantially parallel to said first transparent substrate and said second transparent substrate,

said display pixel is connected to an external controller which controls the applied electric field freely according to a display pattern, and

a distance between pairs of said pixel electrodes and said common electrodes, a width of said pixel electrodes, and a width of said common electrodes are constant;

said active-matrix liquid crystal display device further comprising an electric field intensity regulator which varies an intensity of the applied electric field during application of the applied electric field to said display pixels, application of said electric field to said display pixels being controlled by said external controller according to said display pattern.

12. An active-matrix liquid crystal display device according to claim 11, wherein said electric field intensity regulator comprises a field shield pixel electrode disposed above at least one of said common electrodes in said display pixel with an insulating layer interposed therebetween, for shielding part of an electric field generated by said common electrode, said field shield pixel electrode having a shape overlapping part of said common electrode.

13. A method of displaying an image on an active-matrix liquid crystal display device according to claim 12, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.

14. A method of displaying an image on an active-matrix liquid crystal display device according to claim 11, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.

15. An active-matrix liquid crystal display device according to claim 11, wherein said electric field intensity regulator comprises a first medium, disposed between a first common electrode and a first pixel electrode, and a second medium, disposed between a second common electrode and a second pixel electrode, in the display pixel, and

wherein said first medium is not identical to said second medium.

16. A method of displaying an image on an active-matrix liquid crystal display device according to claim 15, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.

17. An active-matrix liquid crystal display device according to claim 11, wherein said electric field intensity regulator comprises a first medium, disposed between a first common electrode and a first pixel electrode, and a second medium, disposed between a second common electrode and said first pixel electrode, in the display pixel, and

wherein said first medium is not identical to said second medium.

18. A method of displaying an image on an active-matrix liquid crystal display device according to claim 17, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.

19. An active-matrix liquid crystal display device according to claim 11, wherein said electric field intensity regulator comprises a first medium, disposed between a first common electrode and a first pixel electrode, and a second medium, disposed between said first common electrode and a second pixel electrode, in the display pixel, and

wherein said first medium is not identical to said second medium.

20. A method of displaying an image on an active-matrix liquid crystal display device according to claim 19, comprising the step of varying the intensity of the applied electric field by manipulating the electric field intensity regulator.