Particulate spacers for touch sensitive overlay panel applications

• US 4,965,421 A
• Filed: 11/08/1988
• Issued: 10/23/1990
• Est. Priority Date: 09/26/1985
• Status: Expired due to Term

• Current Assignee: Dynapro Technologies, Inc.
• Original Assignee: John Fluke Mfg. Co., Inc.
• Inventors: Epperson, David L.
• Primary Examiner(s): Sholl, Linda J.
• Application Number:
  US07/269,749
• Time in Patent Office: 714 Days
• Field of Search: 200/159 B, 200/5 A, 200/512, 200/514, 428/325, 427/427, 427/108-110
• US Class Current: 200/514
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 13/703 characterised by spacers between contact carrying layers
• CPC Class Codes: H01H 2209/038 transparent
• CPC Class Codes: H01H 2209/06 transparent
• CPC Class Codes: H01H 2209/082 transparent
• CPC Class Codes: H01H 2211/01 Ink
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]

Abstract

Fine particles, of predetermined composition and sized to be within a predetermined size range, are deposited on, and thereafter adhere in random distribution to, one of two adjacent surfaces, serving to keep the surfaces uniformly spaced apart except when an external force causes them to make local contact. The particles are conveniently applied in the form of a spray of a suspension of particles and a fluid carrier material, preferably water with alumina particles, or an aqueous solution of a chloride salt of an alkaline earth metal such as calcium, potassium or sodium when small glass beads are used as the particles. Brown alumina particles (approximately 96% Al₂ O₃) in the size range 3-50 microns, so utilized, are found well suited as parallel surface spacers in optically transparent touch sensitive overlay (TSO) panels. Particle distribution densities in the range 300-1,000 particles per inch are satisfactory for TSO panels, with the higher particle density requiring a higher actuation pressure to be applied.

Claims

1. An apparatus in which two closely spaced apart normally parallel layers of material are positioned to be moved closer relative to one another in order to establish local contact therebetween only when and where one of the normally parallel layers is subjected to the action of an external force, comprising:

a first layer of a first transparent material comprising a first surface and a parallel second surface;

a second layer of a second transparent material comprising a third surface and a parallel fourth surface, said third surface being positioned adjacent and parallel to said second surface of said first layer;

optically-transparent, randomly non-uniformed sized, substantially similarly shaped particles comprising a third material which are randomly distributed in a predetermined density between said first and second layers and adhered to at least one of said second and third surfaces, wherein a largest-sized portion of said particles are in simultaneous contact with said second and third surfaces and said first and second layers are maintained separate at a corresponding distance apart in the absence of an external force applied onto one of said layers such that said adjacent surfaces are placed in contact with one another when and where said external force is applied.

2. The apparatus of claim 1, wherein:

said particles are spherical.

3. The apparatus of claim 2, wherein:

said optically-transparent particles are of a size about 3 to 100 microns and are randomly distributed at a density of about 300 to 1,000 particles per square inch.

4. The apparatus of claim 2 wherein:

said first surface is the touch surface of a touch-sensitive overlay panel.

5. The apparatus of claim 4, wherein:

said third material is selected from the group consisting of glass beads and a vinyl polymer.

6. The apparatus of claim 4, wherein:

said particles comprise a material selected from the group consisting of an inelastic material and an elastic material.

7. The apparatus of claim 4 obtained by a method comprising the steps of:

randomly depositing and adhering said particles onto at least one said second and third surfaces in said predetermined density; and

juxtaposing said second and third surfaces so that said largest-sized portion of said particles make simultaneous contact therewith.

8. The apparatus of claim 7, wherein:

said particles are deposited by spraying thereof onto at least one of said second and third surfaces.

9. An apparatus in which two closely spaced-apart light-transmitting normally parallel layers are positioned to be moved closer to one another to establish local contact therebetween under the action of an external force, comprising:

a first layer of a first optically-transparent material comprising a first surface and a parallel second surface, wherein said first surface receives incident light and transmits a first portion of said light through said first layer and out through said second surface;

a second layer of a second optically-transparent material comprising a third surface and a parallel fourth surface, said third surface being positioned adjacent to said second surface; and

optically-transparent, randomly non-uniformly sized, substantially similarly shaped particles comprising a third material which are randomly distributed in a predetermined density between said first and second layers and adhered to at least one of said second and third surfaces, wherein a largest-sized portion if said particles are in simultaneous contact with said second and third surfaces and said first and second layers are maintained separate at a corresponding distance apart in the absence of an external force applied onto one of said layers such that said adjacent surfaces are placed in contact with one another when and where said external force is applied, the minimum separation between said adjacent surfaces at any location being determined in the absence of an external force by the smallest of said particles at that location.

10. The apparatus of claim 9, wherein said first transparent material is MYLAR (TM).

11. The apparatus of claim 9, wherein:

said first surface is the touch surface of a touch-sensitive overlay panel.

12. The apparatus of claim 9, wherein:

said particles are of a size about 3 to 100 microns and are randomly distributed at a density of about 300 to 1,000 particles per square inch.

13. The apparatus of claim 9, wherein:

said particles comprise a material selected from the group consisting of glass beads and a transparent vinyl polymer.

14. The apparatus of claim 13, wherein:

said particles are spherical.

15. The apparatus of claim 9, wherein:

said particles comprise a material selected from the group consisting of an inelastic material and an elastic material.

16. The apparatus of claim 9, obtained by a method comprising the steps of:

randomly depositing and adhering said particles onto at least one of said second and third surfaces in said predetermined density; and

juxtaposing said second and third surfaces so that said largest-sized portion of said particles make simultaneous contact therewith.

17. The apparatus of claim 16, wherein:

said particles are deposited by spraying thereof onto at least one of said second and third surfaces.

18. An apparatus in which two closely space-apart, light-transmitting, electrically-conducting, normally-parallel layers of transparent material are positioned to be moved closer relative to one another to establish local contact therebetween under the action of an external force, comprising:

a first layer of a first electrically non-conductive optically-transparent material comprising a first surface and a parallel second surface;

a first electrically-conductive material of optically-transparent thickness which is attached to said second surface in a first set of zones of predetermined shape, size and orientation;

a second layer of a second electrically non-conductive optically-transparent material comprising a third surface and a parallel fourth surface;

a second electrically-conductive material of optically-transparent thickness which is attached to said third surface in a second set of zones of predetermined shape, size and orientation, said first and second sets of electrically-conductive zones being positioned adjacent and normally parallel to one another; and

electrically non-conductive, randomly non-uniformly sized, substantially similarly shaped particles comprising a third material which are randomly distributed at a predetermined density on said second set of zones, wherein a largest-sized portion of said particles are in simultaneous contact with at least one zone from each of said first and second sets and said sets of zones are thereby maintained separate at a corresponding distance apart in the absence of an external force applied onto one of said layers such that at least one zone each from each of said sets of zones are placed in electrical contact with one another where said external force is applied, the minimum separation between said adjacent surfaces at any location being determined in the absence of an external force by the smallest of said particles at that location.

19. The apparatus of claim 18, wherein:

said first transparent material is MYLAR (TM).

20. The apparatus of claim 18, wherein:

said first surface is the touch surface of a touch-sensitive overlay panel.

21. The apparatus of claim 18, wherein:

said first and second electrically-conductive materials are gold.

22. The apparatus of claim 18, wherein:

said first electrically-conductive material comprises a material selected from a group comprising metals and metal oxides.

23. The apparatus of claim 18, further comprising:

electrical pathways linking at least one zone of said first and second sets of zones to an electrical circuit.

24. The apparatus of claim 18, wherein:

said particles are of a size in the range 3 to 100 microns and are randomly distributed at a density in the range 300 to 1,000 particles per square inch.

25. The apparatus of claim 18, wherein:

said particles comprise a material selected from a group consisting of vinyl polymer and glass, in the form of beads.

26. The apparatus of claim 18 obtained by a method comprising the steps of:

randomly depositing and adhering said particles onto at least one of said first and second sets of electrically-conductive zones in said predetermined density; and

juxtaposing said first and second sets of zones so that said largest-sized portion of said particles makes simultaneous contact therewith.

27. The apparatus of claim 26, wherein

said particles are deposited by spraying thereof onto at least one of said first and second sets of zones.