Front cover assembly for touch sensitive device

• US 5,923,319 A
• Filed: 11/07/1997
• Issued: 07/13/1999
• Est. Priority Date: 05/08/1995
• Status: Expired due to Fees

• Current Assignee: Toshiba Global Commerce Solutions Holdings Corporation (Toshiba Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Crompton, Dennis, Connor, Alfred William, Bishop, Edward H., McDonald, Mark Gehres, Cox, Aaron Roger
• Primary Examiner(s): Saras, Steven J.
• Assistant Examiner(s): SURACI, JOHN F
• Application Number:
  US08/966,029
• Time in Patent Office: 613 Days
• Field of Search: 345/173, 345/175, 345/177, 345/204, 345/174, 345/123, 341/31, 445/22, 250/221, 348/818, 178/18.04, 178/18.01
• US Class Current: 345/175
• CPC Class Codes: G06F 1/1607 Arrangements to support accessories mechanically attached to the display housing G06F1/1603, G06F1/1605 take precedence
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

A front cover assembly is provided for use with a touch sensitive display device. The touch sensitive display device includes a display such as a Cathode Ray Tube (CRT) or Liquid Crystal Display (LCD). The front cover assembly has a top cover, an infrared bezel and a piece of glass. The top cover is inserted into a mold along with the piece of glass. The top cover and glass are then held in place by a vacuum while polyurethane is injected to fill the void between the glass and the top cover and the mold. The polyurethane is injected using injection molding techniques. The polyurethane used must have the properties of flexibility, durability and must also be transparent to infrared light. The polyurethane provides a mechanical lock around the glass and top cover and thus the polyurethane compensates for the different rates of expansion and contraction of the glass and the top cover due to temperature variations in the ambient environment. The polyurethane provides a mechanical lock that prevents liquids from seeping or entering from the top portion of the front cover assembly protecting the touch sensitive display device.

Claims

1. A front cover assembly for an infrared touch sensitive device comprising:

a top cover;

a piece of glass;

a bezel for securing said glass to said top cover wherein said bezel is formed by injection molding polyurethane between said glass and said top cover while said glass and said top cover are held in a fixed relationship to each other, wherein said bezel forms a mechanical lock between the top cover and the glass provides a liquid tight seal; and

a plurality of spaced tab members formed in and spaced about the periphery of the bezel providing a small gap between the touch sensitive device and the glass for diffusing a touch force to reduce bleeding or puddling of the touch sensitive device when the touch force is applied to the glass.

2. The front cover assembly of claim 1 wherein the bezel is a unitary member.

3. The front cover assembly of claim 1 further comprising a frame surrounding the touch sensitive device and receiving touch forces transferred thereto by the tab members.

4. A method of making a front cover assembly using an injection molding technique for a touch sensitive device comprising the steps of:

inserting a piece of glass along with a top cover in a mold wherein said glass and said top cover are held in place relative to each other by a vacuum;

injecting polyurethane into said mold between said glass and said top cover to create an integral bezel including a plurality of spaced tabs about the periphery of the bezel and forming a mechanical lock and a liquid proof seal between said glass and said top cover;

compensating for different rates of expansion and contraction of the top cover and glass in maintaining the mechanical lock and liquid seal; and

transferring touch forces from the bezel to a frame surrounding the bezel.

5. The method of claim 4 further comprising the step of forming tab members in the bezel to provide a small gap between the touch sensitive device and the glass and wherein the tab members reduce puddling or bleeding of the touch sensitive device when a touch force is applied to the glass.

6. A display tablet comprising:

a front cover assembly having a top cover, a piece of tempered glass, and a bezel for securing said glass to said top cover wherein said bezel is formed by injection molding technique wherein polyurethane is injected between said tempered glass and said top cover while said tempered glass and said top cover are held in place relative to each other, wherein said bezel forms a mechanical lock between the top cover and the glass that provides a liquid tight seal;

a plurality of spaced tab members formed in and spaced about the periphery of the bezel providing a small gap between the top cover assembly and the glass for diffusing a touch force to reduce bleeding or puddling when the touch force is applied to the glass;

a touch ring disposed around said bezel of said front assembly, said touch ring forming an infrared grid over said glass of said front cover assembly;

a touch controller coupled to said touch ring for controlling said touch ring and providing touch input coordinates;

a liquid crystal display disposed next to said glass of said front cover assembly; and

a rear front cover assembly mated to said front cover assembly wherein said touch ring, said liquid crystal display, and said touch controller are disposed therein.

7. The display tablet of claim 6 further comprising:

a frame surrounding the liquid crystal display and receiving touch forces transferred thereto by the tab members.

8. The display tablet of claim 6 wherein said bezel compensates for different rates of expansion and contraction of the top cover and glass in maintaining the mechanical lock and liquid seal.

9. The display tablet of claim 6 wherein the bezel is a unitary member.

10. A computer system comprising:

a system unit;

a touch sensitive device having an infrared touch input device and a LCD in a frame;

a front cover assembly having a top cover with inner edges describing an opening in said top cover, said top cover made of a polycarbonate material;

a piece of glass that fits within said opening in said top cover; and

a bezel for securing said glass to said top cover wherein said infrared bezel is formed by an injection molding technique wherein polyurethane is injected between said glass and said top cover while said glass and said top cover are held in place, wherein said bezel forms a mechanical lock between the top cover and the glass that provides a liquid tight seal; and

a plurality of spaced tab members formed in and spaced about the periphery of the bezel providing a small gap between the touch sensitive device and the glass for transferring a touch force to the frame to reduce bleeding or puddling of the touch sensitive device when a touch force is applied to the glass.

11. The front cover assembly of claim 10 further comprising:

a frame surrounding the infrared touch sensitive device and receiving touch forces transferred thereto by the tab members.

12. The front cover assembly of claim 10 wherein the bezel is a unitary member.

13. The front cover assembly of claim 10 wherein said bezel compensates for different rates of expansion and contraction of the top cover and glass in maintaining the mechanical lock and liquid seal.

14. A front cover assembly for an infrared touch sensitive device comprising:

a top cover having inner edges describing an opening in said top cover, said top cover made of a polycarbonate material;

a piece of glass that fits within said opening in said top cover;

an infrared bezel for securing said glass to said top cover wherein said infrared bezel is formed by an injection molding technique wherein polyurethane is injected between said glass and said top cover while said glass and said top cover are held in place relative to each other, wherein a liquid tight seal is created between said glass, said top cover and said infrared bezel;

said bezel compensating for different rates of expansion and contraction of the top cover and glass by maintaining a mechanical lock and liquid seal therebetween; and

a plurality of spaced tab members formed in and spaced about the periphery of the bezel providing a small gap between the touch sensitive device and the glass for diffusing a touch force to reduce bleeding or puddling of the touch sensitive device when a touch force is applied to the glass.

15. The front cover assembly of claim 14 further comprising:

a frame surrounding the liquid crystal display and receiving touch forces transferred thereto by the tab members.

16. The front cover assembly of claim 14 wherein the bezel is a unitary member.