Layered pressure transducer land method for making same

• US 5,847,639 A
• Filed: 09/29/1997
• Issued: 12/08/1998
• Est. Priority Date: 02/17/1994
• Status: Expired due to Term

• Current Assignee: Interlink Electronics Incorporated
• Original Assignee: Interlink Electronics Incorporated
• Inventors: Yaniger, Stuart I.
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): EASTHOM, KARL D
• Application Number:
  US08/939,335
• Time in Patent Office: 435 Days
• Field of Search: 338/99, 338/114, 338/92, 338/47
• US Class Current: 338/99
• 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 13/703 characterised by spacers between contact carrying layers
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 2201/028 Indium tin oxide [ITO]
• CPC Class Codes: H01H 2209/082 transparent
• CPC Class Codes: H01H 2211/014 universal
• CPC Class Codes: H01H 2239/078 Variable resistance by variable contact area or point

Abstract

A variable resistance transducer responsive to an applied pressure including a smooth resistive layer on a flexible substrate and deposited thereon by printing or imaging technology, small points of nonconductive or semiconductive material, and resistive interdigitating fingers where in one finger is a wiper so that position on the resistive layer can be sensed.

Claims

1. A pressure sensitive potentiometer comprising:

a first flexible layer having a smooth semiconducting surface and deposited thereon small raised points of nonconductive material; and

a second layer adjacent the first layer and separated from the first layer by the raised points of nonconductive material, the second layer having a first and a second set of interdigitating resistive fingers, the first set of fingers being connected to a resistive bar portion running across the second layer perpendicular to the first and second set of fingers, the bar portion being coupled between a preselected voltage applied to first and second electrodes connected to respective ends of the bar portion, the second set of fingers being connected to a wiper arm running across the second layer parallel to the bar portion, wherein one of the second set of fingers, in response to an applied pressure to the first layer which causes the first layer to deform around the raised points of material thereby making contact with the second layer, is shunted by the first layer to one of the first set of fingers so that a voltage at an electrode connected to the wiper arm is proportional to a distance along which the pressure is applied.

2. A pressure sensitive transducer for measuring two orthogonal positions comprising:

a first layer having a first and a second set of interdigitating resistive fingers spanning top to bottom, the first set of fingers being connected to a resistive bar portion running across the first layer perpendicular to the first and second set of fingers, the bar portion being coupled between a preselected voltage applied to first and second electrodes connected to respective ends of the bar portion, the second set of fingers being connected to a wiper arm running across the first layer parallel to the bar portion;

a second layer having a first and a second set of interdigitating resistive fingers spanning left to right, the first set of fingers being connected to a resistive bar portion running across the second layer perpendicular to the first and second set of fingers, the bar portion being coupled between a preselected voltage applied to first and second electrodes connected to respective ends of the bar portion, the second set of fingers being connected to a wiper arm running across the second layer parallel to the bar portion; and

a third layer having a first and second side separated by a nonconducting material and having smooth semiconducting surfaces on each of its sides and deposited thereon small raised points of nonconductive material, and having regions of non-deposited material between the small raised points, the third layer being sandwiched between the first and second layers, and separated therebetween by the small points

wherein one of the second set of fingers of the first layer in response to an applied pressure to the third layer is shunted by the third layer to one of the first set of fingers of the first layer so that a voltage at an electrode connected to the wiper arm of the first layer is proportional to a distance along which the pressure is applied top to bottom of the first layer;

wherein one of the second set of fingers of the second layer in response to an applied pressure to the third layer is shunted by the third layer to one of the first set of fingers of the second layer so that a voltage at an electrode connected to the wiper arm of the second layer is proportional to a distance along which the pressure is applied left to right of the second layer;

wherein the third layer is flexible and responsive to the applied pressure to deform around the raised points of material thereby making contact with the first and second layers in the regions between the deposited raised points.

3. A pressure sensitive transducer as recited in claim 2 wherein the first, second, and third layers are transparent.