White touch pads for capacitive touch control panels

• US 4,855,550 A
• Filed: 01/04/1988
• Issued: 08/08/1989
• Est. Priority Date: 01/04/1988
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Schultz, John Jr.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US07/140,392
• Time in Patent Office: 582 Days
• Field of Search: 200/5 A, 200/159 B, 200/52 R, 200/DIG. 04, 200/308, 200/310, 200/600, 361/280, 361/300, 361/330, 361/278, 340/365 C, 400/479.1, 341/33
• US Class Current: 200/600
• CPC Class Codes: F24C 7/082 on ranges, e.g. control panels, illumination
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2017/9615 using three electrodes per touch switch
• CPC Class Codes: H03K 2217/96077 comprising an electrode which is floating
• CPC Class Codes: H03K 2217/960775 Emitter-receiver or "fringe" type detection, i.e. one or more field emitting electrodes and corresponding one or more receiving electrodes

Abstract

A capacitive touch pad assembly which provides a touch control panel for an appliance with white touch pad appearance. A thin dielectric substrate has an outer touch electrode of a relatively dark-colored conductive material deposited on its outer surface and a pair of spatially separated inner electrodes formed on the inner surface of the dielectric layer for connecting to the control circuitry. To achieve a light-colored appearance for the touch pads, a layer of relatively light-colored non-conductive decorative material is applied to the outer surface overlaying the electrode to hide its dark color except for a small exposed area of the electrode which defines a symbol relating to the function of the pad. The exposed area may be covered by a second layer of dark conductive material or left exposed. The symbol enables direct human body member contact with the outer electrode.

Claims

1. A capacitive touch pad assembly comprising:

a layer of dielectric material having an outer surface and an inner surface;

an outer electrode comprising a first thin layer of relatively dark-colored conductive material fabricated on said outer surface to be responsive to contact with a human body member;

a pair of spatially separated inner electrodes fabricated on said inner surface substantially within the boundaries of said outer electrode;

said inner electrodes being adapted for electrical contact with external electronic control circuitry;

a layer of relatively light-colored non-conductive decorative material applied to said outer surface substantially overlaying said outer electrode, surrounding a small exposed area of said outer electrode, said exposed area defining a symbol to be touched;

whereby said pad provides a pleasing light-colored appearance with a contrasting dark symbol, said symbol providing the means for direct human body member contact with said outer electrode.

2. The touch pad assembly of claim 1 wherein said relatively dark conductive material is a screenable paste comprising a mixture of finely ground black glass, a conductive metallic component and an organic medium.

3. The touch pad assembly of claim 2 wherein said relatively light-colored non-conductive decorative material comprises a white ceramic enamel.

4. The touch pad assembly of claim 1 wherein said symbol identifies the function of said touch pad.

5. A capacitive touch pad assembly comprising:

a layer of dielectric material having an outer surface and an inner surface;

a first outer electrode comprising a thin layer of relatively dark-colored conductive material fabricated on said outer surface to be responsive to contact with a human body member;

a pair of spatially separated inner electrodes fabricated on said inner surface underlying said first electrode and adapted for electrical connection with external electronic circuitry;

a thin layer of relatively light-colored non-conductive decorative material deposited on said outer surface overlying said outer electrode defining an uncovered area of said outer electrode; and

a second outer electrode comprising a second thin layer of relatively dark-colored conductive material deposited on said uncovered area and that portion of said thin decorative layer adjacent said uncovered area, said second layer defining a symbol to be touched;

whereby said pad provides a pleasing light-colored appearance with a contrasting dark symbol, said symbol being exposed for direct contact with a human body member and in good electrical contact with said outer electrode.

6. The touch pad assembly of claim 5 wherein said relatively dark conductive material is a screenable paste comprising a mixture of finely ground black glass, a conductive metallic component and an organic medium.

7. The touch pad assembly of claim 6 wherein said relatively light-colored non-conductive decorative material comprises a white ceramic enamel.