High aperture AMLCD with nonparallel alignment of addressing lines to the pixel edges or with distributed analog processing at the pixel level

• US 5,563,727 A
• Filed: 06/30/1994
• Issued: 10/08/1996
• Est. Priority Date: 06/30/1994
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Larson, Brent D., Ellis, Roger K.
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): Malinowski, Walter J.
• Application Number:
  US08/268,590
• Time in Patent Office: 831 Days
• Field of Search: 359/59, 359/54, 359/53, 359/88, 359/87, 345/90
• US Class Current: 349/143
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/134309 characterised by their geometrical arrangement
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence

Abstract

An approach for constructing active matrix liquid crystal light valves having very high aperture ratio is described. This is achieved by a burying the pixel addressing elements beneath a planarized array of nearly contiguous pixel electrodes and minimizing the footprint of opaque structures in the light valve. Undesirable field-induced disclinations and deformations of the liquid crystal are minimized by shielding the addressing structures with the pixel electrodes. Embodiments are provided which utilize the approach to improve transmittance, image quality, yield, design flexibility and functionality of the display.

Claims

1. A transmissive light valve with high aperture architecture constructed through steps comprising:

providing an active matrix substrate, said substrate manufactured through steps, comprising;

providing a substrate;

forming an active matrix addressing means on one side of said substrate, said active matrix addressing means, wherein said active matrix addressing means comprises a plurality of addressing lines, and a plurality of active pixel circuits in electrical connection with the plurality of addressing lines;

depositing an insulating dielectric layer over said active matrix addressing means;

depositing a plurality of pixel electrodes which are substantially contiguous and substantially transparent to a range of optical wavelengths, on the opposite side of the insulating layer with respect to said plurality of addressing lines, where a subset of said addressing lines are situated under said pixel electrodes and are aligned in a nonparallel fashion with respect to the edges of said pixel electrodes; and

establishing an electrical contact between each of said pixel electrodes and a corresponding active pixel circuit;

positioning an electro-optic medium comprised of liquid crystal proximate to said active matrix substrate, wherein the electro-optic medium is substantially electrically shielded from the plurality of addressing lines by said plurality of pixel electrodes; and

providing a backplane substrate proximate to said electro-optic medium.

2. The transmissive light valve of claim 1 wherein said electro-optic medium is a liquid crystal.

3. The transmissive light valve of claim 2 wherein the liquid crystal is free of disclinations in the vicinity of a plurality of adjacent pixels having equal applied voltages.

4. The transmissive light valve of claim 1 wherein said plurality of addressing lines comprise both row and column addressing lines.

5. The transmissive light valve of claim 4 wherein said pixel electrodes are arranged in rows and the pixel electrodes in each row are laterally offset from the pixel electrodes in adjacent rows.

6. The transmissive light valve of claim 1 wherein the insulating dielectric layer is in the range of 0.5 microns to 5 microns thick.

7. The transmissive light valve of claim 1 wherein the insulating dielectric layer is a planarization layer deposited over said addressing lines.

8. The transmissive light valve of claim 1 wherein the electrical connection between the plurality of active pixel circuits and the plurality of addressing lines comprise one or more ohmic connections (vias) per pixel electrode.

9. The transmissive light valve of claim 1 wherein the electrical connection between the plurality of active pixel circuits and the plurality of addressing lines comprise one or more non-ohmic connections (vias) per pixel electrode.

10. The transmissive light valve of claim 1 wherein the electrical connection between the plurality of active pixel circuits and the plurality of addressing lines is provided by capacitive coupling means.

11. The transmissive light valve of claim 10, further comprising means for achieving half-tone response from said plurality of pixel electrodes.

12. The transmissive light valve of claim 1 wherein each of said plurality of pixel electrodes is nearly contiguous with a subset of surrounding pixel electrodes.

13. The transmissive light valve of claim 1 wherein a subset of said addressing lines are situated under spaces between said pixel electrodes.

14. The transmissive light valve of claim 1, further comprising light masking means for blocking light near the perimeter of the pixel electrodes.

15. The transmissive light valve of claim 1, wherein said electro-optic medium contains local disinclinations.

16. The transmissive light valve of claim 1 wherein said plurality of active pixel circuits are constructed using high mobility silicon or polysilicon.

17. The transmissive light valve of claim 1 wherein of said pixel electrodes are addressed by redundant addressing lines, and each the redundant addressing lines is laterally offset from one another.

18. The transmissive light valve of claim 1 further comprising a color filter array.

19. The transmissive light valve of claim 1 wherein:

said pixel electrodes are arranged in rows of distinct pixels; and

the number of distinct (non-redundant) row addressing lines is substantially different from the number of rows of pixel electrodes.

20. The transmissive light valve of claim 1 wherein each of said plurality of pixel electrodes is nonrectangular in shape.

21. The transmissive light valve of claim 1 further comprising multiple domain alignment of the liquid crystal within each of the pixel electrodes, wherein any disinclinations between domains are masked by said addressing lines.

22. The transmissive light valve of claim 1 wherein all interconnects to the active matrix substrate are located near one edge of said active matrix substrate.

23. The transmissive light valve of claim 1 wherein a plurality of the active matrix substrates are electrically linked to form a tiled transmissive light valve with high aperture architecture.

24. A transmissive active matrix liquid crystal light valve with high aperture architecture, comprising:

an active matrix substrate, comprising;

an insulating layer;

a plurality of addressing lines having shared contacts situated on one side of said insulating layer;

a plurality of pixel electrodes which are nearly contiguous and substantially transparent to a range of optical wavelengths, and situated on the opposite side of the insulating layer with respect to said plurality of addressing lines, where a subset of said addressing lines are situated under said pixel electrodes and are aligned in a nonparallel fashion with respect to the edges of said pixel electrodes;

a plurality of active pixel circuits in electrical connection with the plurality of addressing lines, where each of said active pixel circuits corresponds to one of the plurality of pixel electrodes; and

electrical coupling means between said pixel electrodes and corresponding active pixel circuits;

an electro-optic medium comprised of liquid crystal proximate to said active matrix substrate, wherein the electro-optic medium is substantially electrically shielded from the plurality of addressing lines by said plurality of pixel electrodes; and

a backplane substrate proximate to said electro-optic medium.

25. The transmissive active matrix liquid crystal light valve of claim 24 wherein all of said shared contacts are external to an area containing said pixel electrodes.

26. The transmissive active matrix liquid crystal light valve of claim 24 wherein said active pixel circuits are comprised of thin film transistors, and said thin film transistors are substantially buried beneath the addressing lines.

27. A transmissive active matrix liquid crystal light valve with high aperture architecture, comprising:

an active matrix substrate, comprising;

an insulating layer;

a plurality of addressing lines situated on one side of said insulating layer;

a plurality of pixel electrodes which are nearly contiguous and substantially transparent to a range of optical wavelengths, and situated on the opposite side of the insulating layer with respect to said plurality of addressing lines;

a plurality of active pixel circuits each comprised of an analog latch circuit and a voltage limiting circuit where an oscillating voltage is applied to said backplane such that an alternating voltage is applied across the electro-optic medium, the amplitude of said alternating voltage being controlled by said analog latching circuit, said plurality of active pixel circuits are in electrical connection with the plurality of addressing lines, where each of said active pixel circuits corresponds to one of the plurality of pixel electrodes and each active pixel circuit contains a plurality of active circuit elements; and

electrical coupling means between said pixel electrodes and corresponding active pixel circuits;

an electro-optic medium comprised of liquid crystal proximate to said active matrix substrate, wherein the electro-optic medium is substantially electrically shielded from the plurality of addressing lines by said plurality of pixel electrodes; and

a backplane substrate proximate to said electro-optic medium.

28. The transmissive active matrix liquid crystal light valve of claim 27 wherein said plurality of active circuit elements contained within each of said active pixel circuits, acts in a redundant fashion.

29. The transmissive active matrix liquid crystal light valve of claim 27 wherein distributed processing is performed by each of the active pixel circuits.

30. The transmissive active matrix liquid crystal light valve of claim 29 wherein said distributed processing comprises data conversion at the pixel.

31. The transmissive active matrix liquid crystal light valve of claim 30 wherein the electro-optic medium is a nematic liquid crystal.

32. The transmissive active matrix liquid crystal light valve of claim 29 wherein sets of said active pixel circuits may be updated asynchronously.

33. The transmissive active matrix liquid crystal light valve of claim 27 wherein said alternating voltage is at a frequency sufficiently high so as to eliminate the perception of flicker.

34. The transmissive active matrix liquid crystal light valve of claim 32 wherein said frequency is greater than or equal to 120 Hz.

35. A transmissive subtractive color active matrix liquid crystal light valve stack with high aperture architecture, comprising:

a plurality of stacked active matrix liquid crystal light valves, where each of said active matrix liquid crystal light valves selectively modulates a range of optical wavelengths and the ranges of the optical wavelengths are substantially non-overlapping, each of said light valves is comprised of;

an active matrix substrate, comprising;

an insulating layer;

a plurality of addressing lines situated on one side of said insulating layer;

a plurality of pixel electrodes substantially transparent to a range of optical wavelengths, and situated on the opposite side of the insulating layer with respect to said plurality of addressing lines, where a subset of said addressing lines are situated under said pixel electrodes and are aligned in a nonparallel fashion with respect to the edges of said pixel electrodes;

a plurality of active pixel circuits in electrical connection with the plurality of addressing lines, where each of said active pixel circuits corresponds to one of the plurality of pixel electrodes; and

electrical coupling means between said pixel electrodes and corresponding active pixel circuits;

an electro-optic medium comprised of liquid crystal proximate to said active matrix substrate, wherein the electro-optic medium is substantially electrically shielded from the plurality of addressing lines by said plurality of pixel electrodes; and

a backplane substrate proximate to said electro-optic medium.

36. The transmissive subtractive color active matrix liquid crystal light valve stack of claim 35, further comprising light masking layers in one or more of the active matrix liquid crystal light valves, where each of said light masking layers selectively blocks the range of optical wavelengths modulated by the active matrix liquid crystal light valves containing the light masking layer while transmitting the ranges of optical wavelengths modulated by the other active matrix liquid crystal light valves.