Liquid crystal display and backlight heater

• US 6,163,359 A
• Filed: 12/02/1998
• Issued: 12/19/2000
• Est. Priority Date: 12/02/1998
• Status: Expired due to Term

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Smith, Bradley Scott, Davis, Kent Wilson, Macomber, Ben G.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/203,964
• Time in Patent Office: 748 Days
• Field of Search: 349/161, 349/72, 349/150, 349/61, 349/64, 313/13, 313/547, 313/595, 315/15, 219/485
• 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 1/133602 Direct backlight

Abstract

A heater for a liquid crystal display and accompanying backlight is provided that is easy to install or remove from a liquid crystal display assembly and that extends the low temperature operation of the backlight and the liquid crystal display. The heater comprises a heating element with a foil-type heating element extending from it. The heating element may be attached to an insulating heater pad with a foil backing. The heater is disposed between the backlight diffuser and the printed circuit board and the foil-type heating element wraps around the backlight. Application of an electrical current to the heating element heats the LCD assembly and the backlight and extends their low temperature operation. The heating element may further comprise a resistive element and the light source may further comprise a fluorescent lamp. The foil-type heating element may further comprise an adhesive layer permitting attachment to the backlight.

Claims

1. A liquid crystal display assembly, comprising:

a liquid crystal display;

a printed circuit board assembly spaced from said liquid crystal display, said printed circuit board assembly electrically connected to said liquid crystal display;

a backlight diffuser disposed between said liquid crystal display and said printed circuit board assembly, said backlight diffuser having a light source located on at least one side of said backlight diffuser, said light source illuminating said liquid crystal display; and

a removable heating element disposed between said backlight diffuser and said printed circuit board assembly, said heating element heating said liquid crystal display through said backlight diffuser, said heating element having a foil-type heating element extending therefrom, said foil-type heating element conducting heat to said light source.

2. The liquid crystal display assembly of claim 1, wherein said light source comprises a fluorescent lamp.

3. The liquid crystal display assembly of claim 1, wherein said heating element further comprises a heater pad attached to said heating element.

4. The liquid crystal display assembly of claim 3, wherein said heating pad further comprises a foil backing.

5. The liquid crystal display assembly of claim 4, wherein said foil backing is comprised of copper.

6. The liquid crystal display assembly of claim 3, wherein said heater pad is comprised of a polyester insulating material.

7. The liquid crystal display assembly of claim 3, wherein said heater pad is comprised of a Kapton material.

8. The liquid crystal display assembly of claim 1, wherein said foil-type heating element is comprised of copper.

9. The liquid crystal display assembly of claim 1, wherein said heating element further comprises a resistive element.

10. The liquid crystal display assembly of claim 1, further comprising a voltage source coupled to said heating element.

11. The liquid crystal display assembly of claim 1, wherein said heating element precludes condensation from forming on an inner surface of said liquid crystal display.

12. A liquid crystal display assembly, comprising:

a liquid crystal display;

a printed circuit board assembly spaced from said liquid crystal display, said printed circuit board assembly electrically connected to said liquid crystal display;

a backlight diffuser disposed between said liquid crystal display and said printed circuit board assembly, said backlight diffuser having a light source located on at least one side of said backlight diffuser, said light source illuminating said liquid crystal display; and

a heating element disposed between said backlight diffuser and said printed circuit board assembly, said heating element heating said liquid crystal display through said backlight diffuser, said heating element having a foil-type heating element extending therefrom, said foil-type heating element conducting heat to said light source;

wherein said foil-type heating element further comprises an adhesive layer, said adhesive layer bonding said foil-type heating element to said light source.

13. A liquid crystal display assembly, comprising:

a liquid crystal display;

a printed circuit board assembly spaced from said liquid crystal display;

a backlight diffuser disposed between said liquid crystal display and said printed circuit board assembly, said backlight diffuser having a light source for providing light to said liquid crystal display; and

means for heating said liquid crystal display and said light source, said heater means including a removable heating element disposed between said backlight diffuser and said printed circuit board assembly.

14. The liquid crystal display assembly of claim 13, wherein said heater means further comprises a heater pad attached to said heating element.

15. The liquid crystal display assembly of claim 14, wherein said heater pad is comprised of insulating material.

16. The liquid crystal display assembly of claim 13, wherein said heating element is comprised of a resistive element.

17. The liquid crystal display assembly of claim 13, wherein said light source is comprised of a fluorescent lamp.

18. The liquid crystal display assembly of claim 13, further comprising a voltage source coupled to said heating element.

19. A liquid crystal display assembly, comprising:

a liquid crystal display;

a printed circuit board assembly spaced from said liquid crystal display;

a light source interposed between said liquid crystal display and said printed circuit board assembly, and

a heating element disposed between said printed circuit board assembly and said liquid crystal display, said heating element heating said liquid crystal display assembly and said light source, whereby said heating element having an adhesive layer in direct contact with said light source to thereby provide easy installation and removal from said liquid crystal display assembly.

20. The liquid crystal display assembly of claim 19, wherein said heating element further comprises a heater pad attached to said heating element.

21. The liquid crystal display assembly of claim 20, wherein said heater pad further comprises a foil backing.

22. The liquid crystal display assembly of claim 21, wherein said foil backing is comprised of copper.

23. The liquid crystal display assembly of claim 20, wherein said heater pad is comprised of a Kapton type material.

24. The liquid crystal display assembly of claim 19, wherein said heating element is comprised of a resistive element.

25. The liquid crystal display assembly of claim 19, further comprising a voltage source coupled to said heating element.

26. The liquid crystal display assembly of claim 25, further comprising:

a microcontroller;

a temperature sensor electrically connected to said microcontroller; and

said microcontroller connected to means for switching voltage source on and off.

27. The liquid crystal display assembly of claim 19, further comprising a backlight diffuser, said backlight diffuser disposed between said liquid crystal display and said heating element, said light source being attached to said backlight diffuser.

28. The liquid crystal display assembly of claim 27, wherein said heating element extends adjacent to said light source, said heating element heating said light source.

29. The liquid crystal display assembly of claim 27, wherein said light source comprises a fluorescent lamp.

30. A liquid crystal display assembly, comprising:

a liquid crystal display;

a printed circuit board assembly spaced from said liquid crystal display;

a heating element disposed between said printed circuit board assembly and said liquid crystal display, said heating element heating said liquid crystal display assembly, whereby said heating element provides easy installation and removal from said liquid crystal display assembly; and

a backlight diffuser disposed between said liquid crystal display and said heating element, said backlight diffuser having a light source attached to said backlight diffuser, wherein said heating element extends adjacent to said light source, said heating element heating said light source, said heating element further comprising means for attaching to said light source, wherein said attaching means comprises an adhesive backing.

31. A liquid crystal display assembly, comprising:

a liquid crystal display;

a printed circuit board assembly spaced from said liquid crystal display;

a backlight diffuser disposed between said liquid crystal display and said printed circuit board assembly, said backlight diffuser having a light source for providing light to said liquid crystal display; and

means for heating said liquid crystal display, said heater means including a heating element disposed between said backlight diffuser and said printed circuit board assembly, said heating element further heating said light source, wherein said heater means further comprises a heater pad attached to said heating element, and wherein said heater pad further comprises a foil backing, said foil backing extending from said heater pad and wrapping partially around said light source.

32. The liquid crystal display assembly of claim 31, wherein said foil backing further comprises an adhesive to fasten said foil backing to said light source.

33. The liquid crystal display assembly of claim 31, wherein said foil backing is comprised of copper.

34. A heating system for use in a liquid crystal display assembly comprising a liquid crystal display, a light source, and a backlight diffuser coupled to said light source and adapted to diffuse light from said light source to illuminate evenly said liquid crystal display, said heater system comprising:

a heater pad having a resistive heating element disposed in a foil backing layer, said backing layer further comprising an adhesive layer, said adhesive layer being adapted for bonding said foil backing layer to said backlight diffuser and to said light source, said resistive heating element thereby providing heat to said liquid crystal display through said backlight diffuser and to said light source;

whereby, upon installation of said heater pad in a liquid crystal display assembly, operation of said heater pad precludes condensation of the liquid crystal display and maintains proper operating temperature of said light source.

35. The heating system of claim 34, wherein said foil backing is comprised of copper.

36. The heating system of claim 34, wherein said resistive heating element is comprised of copper.

37. The heating system of claim 34, wherein said heater pad further comprises polyester insulating material.

38. The heating system of claim 34, wherein said heater pad further comprises Kapton material.

39. The heating system of claim 34, wherein said heater pad further comprises means for controlling temperature of said resistive heating element.