Electronic pressure sensitive transducer apparatus

• US 4,314,227 A
• Filed: 09/24/1979
• Issued: 02/02/1982
• 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.
• Application Number:
  US06/078,323
• Time in Patent Office: 862 Days
• Field of Search: 338/69, 338/99, 338/114, 338/100, 200/5 A, 200/264, 252/518, 84/DIG. 7, 340/365 A
• 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 10/106 on resistive material dispersed in an elastic material H01C10/103 and H01C10/12 take precedence; for electric switches H01H1/029
• 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 pressure responsive, variable resistance, analog switch has first and second conductors interleaved in spaced-apart relationship and disposed on a base member. An insulative spacer ring is positioned around and rises above the first and second conductors. A resilient cover sheet is attached to the top of the insulative spacer ring in spaced relationship over the conductors to define an enclosure between the resilient cover sheet and the base member. A pressure sensitive resistive conductor composition is disposed on the resilient cover sheet or on the conductors in the enclosure to interconnect a resistance between the first and second conductors when the resilient cover sheet is depressed against the conductors. The amount of resistance so interconnected varies inversely to the amount of pressure exerted.

Claims

1. A pressure responsive analog transducer comprising:

a first contact;

a second contact;

at least one semiconducting layer comprising at least a pressure sensitive semiconductor particulate material, the semiconducting layer disposed in normally spaced relationship with at least one of the first and secon contacts, the semiconducting layer having a surface positioned in normally non-electrically-conducting relationship with at least one of the first and second contacts, the surface having a multiplicity of microprotrusions extending therefrom, each providing a minute contact location, at least one of the first contact, second contact and semiconducting layer being resiliently responsive to an external pressing force for causing the multiplicity of microprotrusions extending from the surface of the semiconducting layer and at least one of the first and second contacts to variably press against one another to define a variably electrically resistive junction so that electricity conducts between the first and second contacts through the minute contact location of the microprotrusions on the surface so that the resistance across the variably electrically resistive junction decreases in response to an increase in the external pressing force and increases in response to a decrease in the external pressing force.

2. The analog transducer of claim 1 further comprising a cover wherein the semiconducting layer is disposed on the surface of the cover for providing a shunt between the first contact and the second contact when the pressing force is applied.

3. The analog transducer of claim 1 further comprising:

a cover; and

a third contact on the surface of the cover in facing relationship to the first and second contacts for selectively forming a shunt between the first and second contacts, the semiconducting layer being disposed to overlay at least one of the first, second and third contacts.

4. The analog transducer of claims 1, 2 or 3 wherein the semiconducting layer further comprises a binder composition mixed with the semiconductor particulate material and the semiconductor particulate material comprises particulated molybdenum disulfide.

5. The analog transducer of claim 4 wherein the molybdenum disulfide particles have a maximum diameter which is less than about 10 microns.

6. The analog transducer of claim 4 wherein the binder composition comprises an acrylic resin.

7. The analog transducer of claim 4 wherein the particulated molybdenum disulfide and binder mixture is applied so that the semiconducting layer has a substantially constant thickness and the exposed surface has a multiplicity of protruding particles each comprising a minute contact location.

8. The analog transducer of claim 4 wherein the weight ratio of binder to particulated molybdenum disulfide is about one-to-one.

9. The analog transducer of claim 5 wherein the weight ratio of binder to particulated molybdenum disulfide is about one-to-one.