ITO heater

• US 20020089638A1
• Filed: 10/31/2001
• Published: 07/11/2002
• Est. Priority Date: 10/31/2000
• Status: Active Grant

• Current Assignee: Terence Leslie Johnson, Varintelligent (BVI) Limited
• Original Assignee: Varintelligent (BVI) Limited
• Inventors: Leung, C.C., Ho, K.P., Law, Y.L., Lee, Richard C.H.
• Granted Patent: US 7,023,519 B2
• Time in Patent Office: Days
• US Class Current: 349/161
• CPC Class Codes: G02F 1/133382 Heating or cooling of liquid crystal cells other than for activation, e.g. circuits or arrangements for temperature control, stabilisation or uniform distribution over the cell
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells

Abstract

The invention relates to an ITO heater for a liquid crystal display, typically a DSTN display which comprises an active liquid crystal cell for optical modulation, characterised by a dummy cell adapted for optical compensation comprising two substrates with liquid crystal therebetween, by a heater, the heater comprising a transparent conductive layer applied to one of the substrates, and by the dummy cell further comprising electrically conductive spacing means for simultaneously maintaining a desired cell gap and equalizing the electrical potential between the two substrates.

Claims

1. A heater for a liquid crystal display (LCD), comprising:

(i)

(i) a dummy cell,

(ii) said dummy cell being adapted for use in the LCD,

(iii) a heater, and

(iv) the heater being embedded in the dummy cell.

2. A heater as defined in claim 1, wherein the heater comprises an indium tin oxide (ITO) heater.

3. A liquid crystal display, comprising

(i) an active liquid crystal cell for optical modulation;

(ii) a dummy cell adapted for optical compensation;

(iii) said dummy cell comprising two substrates with liquid crystal therebetween;

(iv) a heater;

(v) Said heater comprising a transparent conductive layer applied to one of said substrates;

(vi) electrically conductive spacing means of said dummy cell for simultaneously maintaining a desired cell gap and equalizing the electrical potential between said two substrates.

4. An LCD as defined in claim 3, wherein there are two conductive electrodes for the heater, one at each respective opposite side of the layer and secured thereto by a conductive adhesive.

5. An LCD as defined in claim 4, wherein the conductive adhesive comprises an anisotropic electrically conductive film.

6. A heater as defined in claim 4, wherein the conductive adhesive comprises electrically conductive glue.

7. An LCD as defined in claim 4, wherein the electrodes each comprises an elongate metal electrode, and wherein the electrodes comprise substantially parallel electrodes.

8. An LCD as defined in claim 7, wherein the metal electrodes each comprise a metal strip or rod.

9. An LCD as defined in claim 4, wherein the electrodes each comprise a flexible printed circuit.

10. An LCD as defined in claim 4, wherein the electrodes each comprise a heat seal.

11. An LCD as defined in claim 4, wherein there is a protective coating for the electrodes.

12. An LCD as defined in claim 4, wherein there is mechanical means to enhance electrical contact between the ITO heater surface and the conductive electrodes.

13. A heater as defined in claim 4, wherein there is a protective and insulating coating for the electrodes.

14. A heater as defined in according to claim 11, wherein the coating comprises silicone.

15. A heater as defined in claim 12, wherein the mechanical means comprises means selected from the group consisting of mechanical clips and clipping devices.

16. A heater as defined in claim 4, wherein the adhesive has electronically conductive beads incorporated therein.

17. An LCD as defined in claim 3, wherein the substrate of the heater comprises a transparent substrate of the dummy cell.

18. An LCD as defined in claim 17, wherein the heater comprises an upper (as viewed) substrate of the dummy cell.

19. An LCD as defined in claim 17, wherein the heater comprises a lower (as viewed) substrate of the dummy cell.

20. An LCD as defined in claim 17, wherein the heater comprises upper and lower (as viewed) substrates of the dummy cell.

21. An LCD display as defined in claim 17, wherein transparent substrates of the dummy cell and heater are laminated by a conductive perimeter adhesive.

22. An LCD display as defined in claim 18, wherein transparent substrates of the dummy cell and heater are laminated by a conductive perimeter adhesive.

23. An LCD display as defined in claim 19, wherein transparent substrates of the dummy cell and heater are laminated by a conductive perimeter adhesive.

24. An LCD display as defined in claim 20, wherein transparent substrates of the dummy cell and heater are laminated by a conductive perimeter adhesive.

25. An LCD as defined in claim 19, wherein the adhesive comprises an epoxy resin.

26. An LCD as defined in claim 25, wherein the adhesive comprises an epoxy resin and conductive spacers.

27. An LCD as defined in claim 23, wherein the epoxy resin comprises a conductive epoxy of high resistivity.

28. An LCD as defined in claims 17, wherein the substrate of the heater comprises glass.

29. An LCD as defined in claim 17, wherein the heater is in contact with the liquid crystal.

30. An LCD as defined in claim 3, wherein the electrodes are connected with a source of electrical power.

31. An LCD as defined in claim 3, wherein the heater comprise an indium tin oxide (ITO) heater.

32. A liquid crystal display as defined in claim 3, wherein the display comprises an active liquid crystal cell for light modulation, and a dummy cell adapted for optical compensation comprising two substrates with liquid crystal therebetween, wherein the transparent conductive layer of the heater is formed on one of the substrates of the dummy cell, and wherein the dummy cell further comprises electrically conductive spacing means for simultaneously maintaining the desired cell gap and equalizing the electrical potential between the two substrates.

33. A device, wherein there is an LCD as defined in claim 3.

34. A device as defined in claim 30, wherein said device is mounted in a vehicle.