AC plasma address liquid crystal display

• US 5,519,520 A
• Filed: 02/08/1994
• Issued: 05/21/1996
• Est. Priority Date: 02/24/1992
• Status: Expired due to Term

• Current Assignee: Feldman Technologies Corporation
• Original Assignee: Photonic Systems Inc. (Photonics Systems Holding GmbH)
• Inventors: Stoller, Ray A.
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): MAI, HUY KIM
• Application Number:
  US08/194,278
• Time in Patent Office: 833 Days
• Field of Search: 359/54, 359/55, 359/84, 345/37, 345/55, 345/60, 345/63, 345/66, 345/102, 345/213, 345/89
• US Class Current: 349/32
• CPC Class Codes: G02F 1/13334 Plasma addressed liquid crystal cells [PALC]
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3662 using plasma-addressed liquid crystal displays

Abstract

A drive system for a matrix cross point addressing system comprises a first substrate having a transparent first linear electrode array thereon. A second substrate having a second linear electrode array thereon, oriented transverse of the first linear electrode array defines therewith a matrix of cross-points. An array of insulating ribs on the second linear electrode array defines an array of channels and an ionizable gas medium fills the array of channels, each channel of the array being aligned with a transparent electrode of the first linear electrode array, respectively. A layer of electric field responsive material, such as a liquid crystal, is sandwiched between the transparent first linear electrode array and a dielectric layer. First circuit means applies a first pulse operating voltage to the first linear electrode array and second circuit means for applying second pulse operating voltage to said second linear electrode array so that the conjoint voltages at selected matrix cross-points (1) causes a discharge in the gas therebetween and forms a charge on the dielectric layer and change the state properties of said electric field responsive material, and (2) remove said charge to cause said material to revert to its initial state, the conjoint voltage applied to the electrodes at a selected site is varied to vary the size charge at selected discharge sites and vary the area of said electric field responsive material at said site which is effected by the charge stored on said dielectric layer.

Claims

1. A display comprising a layer of liquid crystal material, said liquid crystal material having a relatively high turn on threshold, a good saturation characteristic, high break-down voltage, high dielectric constant and fast switching and relaxation times,

a pair of transparent members sandwiching said layer of liquid crystal material, one of said transparent members having a charge storage surface,

transparent electrode means on a first one of said pair of transparent members,

means forming a charge on said charge storage surface and modulating the size of said charge on said charge storage surface, and means for applying a voltage to said transparent electrode for controlling light transmissive characteristics of said liquid crystal material.

2. The display defined in claim 1 wherein said means forming a charge includes an AC plasma discharge.

3. The display defined in claim 2 wherein said transparent electrode means is an array of transparent electrodes on said first one of transparent members, said liquid crystal material being contiguous to said transparent electrodes, said means forming a charge on one of said transparent members including a plurality of ionizable gas filled channels substantially aligned with said transparent electrodes, respectively, and said charge storage surface being contiguous to said ionizable gas filled channels, a further electrode array transverse to said ionizable gas filled channels, and means selectively supplying voltages to said electrode arrays such that conjoint voltages between intersections of said selected electrodes in said arrays discharges said gas to form said charges.

4. The display defined in claim 3 including means for selectively removing said charges.

5. The display defined in claim 4 wherein said means for removing said charges includes means for selectively applying reverse conjoint voltages to selected ones of said electrodes.

6. The display defined in claims 3 wherein said further electrode array has a protective coating thereon.

7. The display defined in claim 3 wherein the number of electrodes in said further electrode array is N and the number of transparent electrodes in said array of transparent electrodes is a multiple of N.

8. The display defined in claim 3 wherein said length of said charge is varied along said ionizable gas filled channel.

9. The display defined in claim 3 wherein said charge on said charge storage surface is caused to spread in proportion to the amplitude of conjoint voltages on selected electrodes of said arrays, said charge spread establishing the spatial size of spot where liquid crystal material changes state, thereby providing spatial gray level of light transmissive point at selected matrix cross points.

10. The display defined in claim 9 including means for selectively applying voltages to said arrays such that the conjoint voltage at a selected matrix cross point where a charge is present causes a discharge and tile removal of said charge.

11. The display defined in claim 10 wherein the spacing between electrodes in said further electrode array is sufficient to allow a predetermined amount of spreading without interfering with the spreading of charge from an adjacent matrix cross point located by the same ionizable gas filled channel.

12. The display defined in claim 3 including means for selectively removing said charges.

13. The display defined in claim 1 including filter means on said transparent electrode means.

14. The display defined in claim 1 wherein in said transparent electrode means is a array of transparent electrodes, sid display having a viewing and non-viewing sides and including red filter means on every third of said transparent electrodes, respectively, blue filter means on a further every third of said transparent electrodes, respectively, and green filter means on the remaining every third of said transparent electrodes, and a planar source of light projected through said display from said non-viewing.

15. The display defined in claim 1 wherein said protective coating includes a thin-film resistive material having high photoemissivity.

16. The display defined in claim 1, including a source of light of a predetermined color projecting through said layer of liquid crystal material and onto a remote display surface for viewing.

37. The display defined in one of claims 1, 17, 24 or 35, including a source of gray scale drive signals connected to said display and a source of light projecting through said layer of liquid crystal material and onto a remote display surface for viewing, and means synchronizing light from said source with gray scale signals from said source of gray scale drive signals for each pixel in the display.

38. The display defined in one of claims 1, 17, 24 or 35, including a source of gray scale signals connected to said display and a red, blue and green light source of light flashes positioned to project light through said display scale signals and means synchronizing said colored light flashes with the gray scale signals for each color flash, respectively.

17. A display system comprising a layer of liquid crystal (LC) medium and a gas discharge matrix means defined by rows and columns of discharge sites for coupling operating potentials to a corresponding matrix of pixel display sites in said LC layer, said LC layer having viewing and non-viewing sides and a source of light illuminating said matrix of pixel display sites from said non-viewing side, said gas discharge matrix means including a first transparent substrate having a first electrode array thereon, a protective coating on said first electrode array and an array of rib means formed on said protective coating defining first lines of discharge sites in said gas discharge medium, a gas medium filling the space between said array of ribs, a thin glass layer on and spanning the space between said ribs, said layer of LC medium being on the surface of said thin glass layer opposite the side on said array of rib means, said LC medium being operated in a saturated, on-off (bi-level) mode where the total area of saturation is directly determined by the spatial area of the gas discharge adjacent thereto, a second transparent substrate having an outer viewing surface and an electrode bearing opposite surface, a transparent second electrode array on said electrode bearing surface and oriented transverse to the orientation of said first electrode array to define said rows and columns of discharge sites, said array of ribs being parallel to one of said transparent electrode arrays, means selectively supplying discharge potentials to said electrode arrays and initiate selective discharges at selected pixel display sites, and means for modulating the spatial area of each gas discharge to directly determine the amount of pixel level gray scale for each pixel display site in said matrix of pixel display sites.

18. The system defined in claim 17 including filter means on each electrode in said transparent second electrode array.

19. The display system defined in claim 18 wherein said filter means includes one or more color filters and said means for modulating includes a source of color information to be displayed.

20. The display system defined in claim 17 wherein said protective coating on said first electrode array is comprised of a resistive layer.

21. The display system defined in claim 17 wherein said protective coating on said first electrode array is a thin film mixture of magnesium oxide and gold.

22. The display system defined in claim 17 wherein said ribs are formed by chemically etching a glass layer on said first electrode array.

23. The display system defined in claim 17 wherein said first and second electrode arrays each have linear electrodes which are orthogonal to each other.

24. A matrix drive system for a liquid crystal display material comprising,

a first substrate having a transparent first linear electrode array thereon,

a dielectric layer,

a second substrate having a second linear electrode array thereon, oriented transverse of said first linear electrode array, to define a matrix of pixel cross-points,

an array of insulating ribs on said second linear electrode array and defining an array of channels and a gas medium filling said array of channels, each channel of said array being aligned with a transparent electrode of said first linear electrode array, respectively,

a layer of liquid crystal material between said transparent first linear electrode array and said dielectric layer,

first circuit means for applying first pulse operating voltage to said first linear electrode array and second circuit means for applying second pulse operating voltage to said second linear electrode array so that the conjoint voltages at selected matrix cross-points (1) causes a discharge in the gas therebetween and forms a charge on said dielectric layer and change the optical properties of said liquid crystal material at said selected matrix cross-points from an initial light transmissive state to a different light transmissive state and (2) remove said charge to cause said liquid crystal material to revert to its initial light transmissive state.

25. The matrix drive defined in claim 24 including means to vary the size charge at selected discharge sites and vary the physical size of the area of said liquid crystal material at said site which has its light transmissive state changed.

26. The matrix drive system defined in claim 25 wherein said means to vary includes means to vary the conjoint voltage applied to said electrodes at a selected pixel site.

27. The matrix drive system defined in claim 25 and including color filter means on said transparent electrodes.

28. The matrix drive system defined in claim 24 including optical filter means at each matrix cross point.

29. A drive system for a matrix cross point addressing system comprising,

a first substrate having a transparent first linear electrode array thereon,

a dielectric layer,

a second substrate having a second linear electrode array thereon, oriented transverse of said first linear electrode array, to define therewith a matrix of cross-points,

an array of insulating ribs on said second linear electrode array and defining an array of channels and a gas medium filling said array of channels, each channel of said array being aligned with a transparent electrode of said first linear electrode array, respectively,

a layer of electric field responsive material between said transparent first linear electrode array and said dielectric layer,

first circuit means for applying first pulse operating voltage said first linear electrode array and second circuit means for applying second pulse operating voltage to said second linear electrode array so that the conjoint voltages at selected matrix cross-points (1) causes a discharge in the gas therebetween and forms a charge on said dielectric layer and change the optical properties of said electric field responsive material at said selected matrix cross-points from an initial light transmissive state to a different light transmissive state and (2) remove said charge to cause said electric field responsive material to revert to its initial light transmissive state, and means to vary includes means to vary the conjoint voltage applied to said electrodes at a selected pixel site to vary the size charge at selected discharge sites and vary the physical size of the area of said electric field responsive material at said site which is effected by the charge stored on said dielectric layer.

30. The drive system defined in claim 29 including filter means at each matrix cross point.

31. The drive system defined in claim 30, said electric field responsive material being a liquid crystal and including color filter means on said transparent electrodes.

32. An electronic control device comprising a layer of material responsive to an electric field,

a pair of transparent members sandwiching said layer of electric field responsive material, one of said transparent members having a charge storage surface,

transparent electrode means on a first one of said pair of transparent members,

means forming a charge on said charge storage surface and applying a voltage to said transparent electrode for controlling the electric field on said layer of material responsive to an electric field, and means for modulating the physical size of the area of said charge on said charge storage surface to thereby modulate the physical size of the area of said layer to which an electric field is applied.

33. The defined in claim 32 wherein said electrode is elongated along a selected axis and said means forming includes means for varying the length of said charge in a direction parallel to said selected axis.

34. The device defined in claim 33 wherein said means forming includes a AC plasma discharge.

35. In a liquid crystal display panel having a viewing side, a liquid crystal medium sandwiched between a pair of thin dielectric members, one of said thin dielectric members being transparent and constituting said viewing side and one of said thin dielectric members constituting a non-viewing side member, a transparent linear electrode array on said viewing side, thin dielectric members and having X number of display electrodes, a gas channel member having a plurality of discharge gas filled channels therein arrayed transversely relative to said linear electrode array, and with said gas filled channels abutting said non-viewing side member, the improvement comprising:

a further linear array of further electrodes aligned with said gas filled channels and isolated from direct electrical contact with the discharge gas in said channels, and

circuit means for applying a voltage to selected ones of said transparent electrodes and said further linear array of further electrodes such that the combined voltages at each display pixel discharges the gas at said pixel and form a charged area on said non-viewing thin dielectric member and vary the light characteristic of the liquid crystal medium according to the physical size of said charged area.

36. An electronic control device comprising a layer of material responsive to an electric field,

a pair of thin insulating members sandwiching said layer of electric field responsive material, one of said thin insulating members having a charge storage surface and one of said thin insulating members being transparent,

transparent electrode means on the transparent insulating member,

means forming a charge on said charge storage surface and applying a voltage to said transparent electrode for controlling the electric field on said layer of material responsive to an electric field, and means for modulating the physical size of the area of said charge on said charge storage surface to thereby modulate the physical size of the area of said layer to which an electric field is applied.