Electronic pressure sensitive force transducer

• US 4,489,302 A
• Filed: 06/13/1983
• Issued: 12/18/1984
• Est. Priority Date: 09/24/1979
• Status: Expired due to Term

• Current Assignee: Interlink Electronics Incorporated
• Original Assignee: Franklin N. Eventoff
• Inventors: Eventoff, Franklin N.
• Primary Examiner(s): Albritton, C. L.
• Assistant Examiner(s): Sears, C. N.
• Application Number:
  US06/492,536
• Time in Patent Office: 554 Days
• Field of Search: 338/69, 338/99, 338/100, 338/114, 200/5 A, 200/264, 340/365 A, 84/DIG. 7
• US Class Current: 338/99
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
• CPC Class Codes: H01C 10/10 adjustable by mechanical pressure or force
• CPC Class Codes: H01H 1/029 comprising conducting material dispersed in an elastic support or binding material
• 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 13/80 characterised by the manner of cooperation of the contacts, e.g. with both contacts movable or with bounceless contacts
• CPC Class Codes: H01H 2201/002 bounceless
• CPC Class Codes: H01H 2203/012 Microprotrusions
• CPC Class Codes: H01H 2203/02 Interspersed fingers
• CPC Class Codes: H01H 2213/002 with external pressure
• CPC Class Codes: H01H 2213/016 in adhesive layer
• CPC Class Codes: H01H 2227/012 Conductive rubber
• CPC Class Codes: H01H 2227/014 Conductive particles
• CPC Class Codes: H01H 2231/018 Musical instrument
• CPC Class Codes: H01H 2239/078 Variable resistance by variable contact area or point
• CPC Class Codes: Y10S 84/07 Electric key switch structure

Abstract

A bounceless switch apparatus having a junction resistance which varies inversely with the pressure applied normally thereto which includes a first conductor member, a pressure-sensitive layer including a semiconducting material covering the first conductor member in intimate electrically conducting contact therewith and a second conductor member positioned in nonelectrically conducting relationship to the pressure-sensitive layer. The pressure-sensitive layer has a first surface with a multiplicity of microprotrusions of the semiconducting material which provide a multiplicity of surface contact locations. As the normally open switch is closed in response to a pressing force applied to urge the second conductor member and the first surface together, the physical contact between the microprotrusions and the second conductor increases thereby variably increasing conduction between the first conductor member and the second conductor member.

Claims

1. A bounceless switch apparatus having a junction resistance which varies inversely with a pressure applied normally thereto, comprising:

a first conductor member;

a pressure sensitive layer comprising a semiconducting material disposed for covering the first conductor member in intimate electrically conducting contact therewith, the pressure sensitive layer having a first surface with a multiplicity of microprotrusions of the semiconducting material extending from the first surface for providing a multiplicity of surface contact locations; and

a second conductor member positioned in substantially nonelectrically conducting relationship to the pressure sensitive layer whereby the bounceless switch apparatus is normally open, the switch being closed in response to a pressing force applied to urge the second conductor member and the first surface together for increasing the physical contact between the microprotrusions and the second conductor, to enable electrical conduction through the contacting microprotrusions, the amount of electrical conduction increasing as the amount of pressing force is increased and decreasing as the amount of pressing force is decreased.

3. The bounceless switch of claims 1 or 2 wherein the semiconducting material is particulated molybdenum disulfide.

2. A bounceless switch apparatus having a surface contact resistance which varies inversely with a pressure applied normally thereto comprising:

a first conductor member;

a first pressure sensitive layer including a semiconducting material disposed for covering the first conductor member in intimate electrically conducting contact therewith and further having a first surface having a multiplicity of microprotrusions extending therefrom;

a second conductor member; and

a second pressure sensitive layer including the semiconducting material disposed for covering the second conductor in intimate, electrically conducting contact therewith and further having a second surface having a multiplicity of microprotrusions extending therefrom, the first and second surfaces being positioned in normally electrically nonconducting relationship with each other, at least one of the first and second conductor members being resiliently movable in response to a pressing force applied thereagainst so that the multiplicity of microprotrusions extending from the first and second pressure sensitive composition layers are urged against one another to enable electrical conduction between the first and second conductor members, the amount of electrical conduction increasing as the pressing force is increased and decreasing as the amount of pressing force is decreased.