Membrane switch with universal spacer means

• US 4,317,013 A
• Filed: 04/09/1980
• Issued: 02/23/1982
• Est. Priority Date: 04/09/1980
• Status: Expired due to Term

• Current Assignee: Oak Industries, Inc. (Corning Incorporated)
• Original Assignee: Oak Industries, Inc. (Corning Incorporated)
• Inventors: Larson, Willis A.
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Ginsburg, Morris
• Application Number:
  US06/138,656
• Time in Patent Office: 685 Days
• Field of Search: 200/5 A, 200/159 B, 29/622
• US Class Current: 200/5.00A
• 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 2211/01 Ink
• CPC Class Codes: H01H 2211/014 universal
• CPC Class Codes: H01H 2213/01 with internal pressure of other switch sites
• CPC Class Codes: H01H 2227/024 Spacer elements
• CPC Class Codes: H01H 2229/028 Adhesive
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A method and apparatus for forming a membrane switch of the type having a flexible membrane, a substrate, first and second conductors formed on the membrane and substrate and spacing means disposed between the first and second conductors. The spacing means is applied to either the membrane or substrate in a uniform pattern of individual spacer areas. The spacer areas are applied in liquid form which is cured or allowed to dry. The pattern of spacer areas can be applied without regard to the location of the conductors. The size, spacing and thickness of the spacer areas allow contact between aligned first and second conductors when the exterior of the membrane is subjected to pressure. Thus the same pattern of spacer areas can be used with any arrangement of conductors.

Claims

1. In a membrane switch, a flexible membrane, a substrate, a plurality of first conductors formed on the membrane, a plurality of second conductors formed on the substrate and spacer means disposed between the first and second conductors, the improvement characterized in that said spacer means is a universal spacer means which can be used with any arrangement of first and second conductors, said universal spacer means comprising a pattern of individual, non-conductive spacer areas on either the membrane or substrate, said spacer areas having a size, spacing and thickness that allows contact between aligned first and second conductors in response to pressure upon the exterior of said membrane while otherwise maintaining said conductors in non-contacting spaced relation.

2. The structure of claim 1 wherein the spacer areas are further on both the membrane and substrate.

3. The structure of claim 1 wherein the first conductor is a shorting bar and the second conductor includes a pair of spaced electrodes having interdigitated fingers connected to separate lead lines.

4. In a membrane switch of the type having a flexible membrane with a plurality of first conductors formed thereon, a substrate with a plurality of second conductors formed thereon, and non-conductive spacer means disposed between the first and second conductors, a method of forming said non-conductive spacer means so as to form a universal spacer means which can be used with any arrangement of first and second conductors, said method including the step of applying to either the membrane or substrate without regard to where the conductors lie, a pattern of individual spacer areas applied in liquid form which is then dried, said spacer areas having a size, spacing and thickness that allows contact between aligned first and second conductors in response to pressure upon the exterior of said membrane while otherwise maintaining said conductors in non-contacting spaced relation.

5. The method of claim 4 further including the step of further applying spacer areas to both the substrate and membrane.

6. The method of claim 4 further characterized in that the first conductor is a shorting bar and the second conductor includes a pair of spaced electrodes having interdigitated fingers and individual lead lines.

7. A method of preparing a membrane switch keyboard of the type having a flexible membrane with a plurality of first conductors formed thereon, a substrate with a plurality of second conductors formed thereon and non-conductive spacing means disposed between the first and second conductors, the method comprising the steps of:

(1) applying the first and second conductors to the membrane and substrate;

(2) applying to either the membrane or substrate, a pattern of individual spacer areas without regard to where the conductors lie, said areas being applied in liquid form which is then dried;

(3) applying adhesive material to the spacer areas; and

(4) placing the membrane on the substrate to complete the keyboard, said spacer areas having a size, spacing and thickness that allows contact between aligned first and second conductors in response to pressure upon the exterior of said membrane while otherwise maintaining said conductors in non-contacting spaced relation.

8. The method of claim 7 further including the step of applying the spacer areas to both the substrate and membrane.

9. The method of claim 7 further including the step of applying adhesive to all the spacer areas.

10. The method of claim 7 further characterized in that the first conductor is a shorting bar and the second conductor includes a pair of spaced electrodes.

11. The method of claim 7 further characterized in that the first and second conductors are applied in liquid form.

12. The method of claim 7 further characterized in that spacer areas are silk-screened onto the membrane or substrate.

13. In a membrane switch, a flexible membrane, a substrate, a set of first conductors on the membrane including a plurality of switch sites, a set of second conductors on the substrate including a plurality of switch sites in facing relation with the switch sites of the first conductors, and a universal spacer means disposed between the first and second conductors and normally holding said conductors in spaced, non-contacting relation, the spacer means having a plurality of openings through which the first conductors may move into contact with the second conductors in response to pressure on the exterior of the membrane, none of the openings being necessarily associated with any particular switch site or conductor.

14. In a membrane switch, a flexible membrane, a substrate, a set of first conductors on the membrane including a plurality of switch sites, a set of second conductors on the substrate including a plurality of switch sites in facing relation with the switch sites of the first conductors, and a universal spacer means disposed between the first and second conductors and normally holding said conductors in spaced, non-contacting relation, said spacer means comprising a pattern of non-conductive spacer areas, none of which is necessarily associated with any particular switch site or conductor.

15. In a membrane switch, a flexible membrane, a substrate, a set of first conductors on the membrane including a plurality of switch sites, a set of second conductors on the substrate including a plurality of switch sites in facing relation with the switch sites of the first conductors, and a universal spacer means which normally maintains the first and second conductors in spaced, non-contacting relation while permitting pressure-responsive contact between aligned switch sites which can be anywhere on the membrane and substrate.