Environmentally-sealed, convectively-cooled active matrix liquid crystal display (LCD)

• US 5,748,269 A
• Filed: 11/21/1996
• Issued: 05/05/1998
• Est. Priority Date: 11/21/1996
• Status: Expired due to Fees

• Current Assignee: Westinghouse Air Brake Technologies Corporation
• Original Assignee: Westinghouse Air Brake Technologies Corporation
• Inventors: Harris, David Bennitt, Kull, Robert Charles, Mathieu, Barry Morris, Dobratz, Jeffrey Alan, Uehling, Mark Allen
• Primary Examiner(s): GROSS, ANITA P
• Application Number:
  US08/754,324
• Time in Patent Office: 530 Days
• Field of Search: 349/58, 349/72, 349/161, 349/12
• US Class Current: 349/58
• CPC Class Codes: G02F 1/133308 Support structures for LCD panels, e.g. frames or bezels
• CPC Class Codes: G02F 1/133311 Environmental protection, e.g. against dust or humidity
• CPC Class Codes: G02F 1/133385 with cooling means, e.g. fans
• CPC Class Codes: G02F 2201/36 Airflow channels, e.g. constructional arrangements facilitating the flow of air

Abstract

A display unit for use with a computer and a power supply, includes an environmentally-sealed enclosure having a removable cover, and housing a liquid crystal display screen, the removable cover serving as an integral heat sink for the power supply, the power supply being mounted on the internal surface of the cover. Further, a backlighting device backlights the display screen, and a cooling plenum conductively and convectively cools the backlighting device, the backlighting device being mounted directly on a surface of the plenum.

Claims

1. A display unit for use with a computer and a power supply, comprising:

an environmentally-sealed enclosure having a removable cover, and housing a liquid crystal display screen, said removable cover serving as an integral heat sink for said power supply, the power supply being mounted on the internal surface of the cover;

backlighting means for backlighting said display screen; and

a cooling plenum for conductively and convectively cooling the backlighting means, said backlighting means being mounted directly on a surface of said plenum.

2. A display unit according to claim 1, wherein said display screen comprises:

a touch screen; and

an overlay bonded to a surface of said touch screen.

3. A display unit according to claim 2, wherein said overlay comprises an acrylic overlay which is electrically conductively coated with an indium-tin-oxide (ITO) coating.

4. A display unit according to claim 3, wherein said display screen further comprises a touch screen frame for housing said touch screen, and wherein a side of said overlay opposite said display screen is sealed to an inner surface of said enclosure by copper foil tape.

5. A display unit according to claim 3, wherein said liquid crystal display screen is mounted directly behind said touch screen.

6. A display unit according to claim 3, wherein said plenum is formed of aluminum.

7. A display unit according to claim 1, wherein a thermally conductive adhesive is positioned between said plenum and said backlighting means for mounting said backlighting means on said plenum, said adhesive being removable and providing a conductive cooling path from said backlighting means to an inner wall of said plenum.

8. A display unit according to claim 1, wherein said plenum creates a sealed air flow path, said display further comprising means for providing forced convection cooling for dissipating heat removed from said sealed flow path created by said plenum.

9. A display unit according to claim 1, wherein said removable cover serves as an integral heat sink for the power supply, said power supply being directly conductively-coupled to the removable cover via one of a film and a paste.

10. A display unit according to claim 1, further comprising a front bezel for sealing said display screen within said enclosure,

wherein each of said front bezel, said enclosure, and said plenum is constructed of aluminum.

11. A display unit according to claim 1, further comprising means for adjusting a temperature of said display unit, means for determining a temperature of said display unit and a multi-stage thermal controller coupled to said temperature adjusting means to selectively adjust a power of said backlighting means when a temperature of said display unit reaches a predetermined level.

12. A display unit according to claim 11, wherein said temperature adjusting means comprises a heater.

13. A display unit according to claim 11, wherein said temperature adjusting means comprises a fan.

14. A display unit according to claim 1, wherein a rectangular orifice is formed at a predetermined position of a bottom of the enclosure to form a channel, and wherein air enters said plenum through the orifice and exits at an air exhaust portion of the removable cover.

15. A display unit according to claim 1, further comprising first and second seals for sealing said enclosure from electromagnetic induction and contaminants, said seals comprising electrically conductive elastomers,

wherein said plenum compresses said first seal at the enclosure bottom when said plenum is coupled to said enclosure, and

wherein said second seal is compressed at a plenum exhaust portion when the removable cover is coupled to said enclosure.

16. A display unit according to claim 1, further comprising a printed board stacked pair assembly comprising a display bulb interconnection printed circuit board and a logic/inverter printed circuit board, said logic/inverter printed circuit having a plurality of inverters and being mounted on a wall of said plenum,

wherein said bulb interconnection printed circuit board includes openings for fitting the inverters therein, to thereby provide a direct thermal path from said plurality of inverters of said logic/inverter printed circuit board to the wall of said plenum,

wherein heat dissipated from the inverters is conductively coupled to an inner wall of said plenum to convectively dissipate heat to an airstream of said plenum.

17. A display unit according to claim 1, further comprising a diffuser having a brightness enhancement film (BEF) mounted between said backlighting means and said liquid crystal display screen,

wherein said BEF is bonded at a perimeter of said diffuser by an adhesive, such that an air pressure equalizes between the BEF and said diffuser, to thereby eliminate formation of trapped air between the BEF and said diffuser,

said diffuser including means for distributing light from said backlighting means and said BEF to thereby form a directed light output.

18. A display unit according to claim 1, further comprising:

means for cooling said backlighting means; and

a heater mounted to said plenum for heating said display screen;

means, coupled to said heater, for sensing a temperature of said display, and for actuating said heater when said temperature falls below a predetermined temperature; and

means for turning off said cooling means when said temperature falls below said predetermined temperature.

19. A display unit according to claim 1, wherein said plenum includes first and second walls, and a stiffener mounted between said first and second walls for damping vibrations of said plenum and preventing deflections of said backlighting means when said display unit is subjected to random vibration and mechanical shock environments.

20. An integrated computer system including:

a power supply;

a display unit powered by said power supply, said display unit comprising;

an environmentally-sealed enclosure having a removable cover, and housing a liquid crystal display screen, said removable cover serving as an integral heat sink for said power supply, the power supply being mounted on the internal surface of the cover;

backlighting means for backlighting said display screen; and

a cooling plenum for conductively and convectively cooling the backlighting means, said backlighting means being mounted directly on a surface of said plenum.