Transducer array

• US 5,578,765 A
• Filed: 06/01/1995
• Issued: 11/26/1996
• Est. Priority Date: 09/18/1992
• Status: Expired due to Fees

• Current Assignee: Incontrol Solutions, Inc.
• Original Assignee: Incontrol Solutions, Inc.
• Inventors: Franz, Patrick J.
• Primary Examiner(s): Chilcot, Richard
• Assistant Examiner(s): BIEGEL, RONALD L
• Application Number:
  US08/457,627
• Time in Patent Office: 544 Days
• Field of Search: 345/173, 345/174, 73/766, 73/862.046, 73/862.041, 73/862.68, 73/767, 382/4, 382/5, 338/49
• US Class Current: 73/862.043
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• 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: G01L 5/228 using tactile array force sensors
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: H01H 2221/012 Joy stick type
• CPC Class Codes: H01H 2239/078 Variable resistance by variable contact area or point

Abstract

A pressure sensitive transducer array in which a plurality of transducers are connected in series and in parallel with one another. In one embodiment, a resistive layer is formed from carbon or silver ink on a polyester film. A plurality of conductive shunt elements having greater conductivity than the resistive layer is formed on a second polyester film. The films are placed adjacent to one another with the shunt elements contacting the resistive layer. Voltage is applied across the resistive layer and pressure is applied thereto. As the pressure increases, the number of current paths set up through contact points on the shunt elements increase thereby decreasing the resistance across the resistive layer and increasing current flow. In another embodiment a plurality of plate elements are contained in a plane on one side of a dielectric layer. A plurality of plate elements are contained in a plane on the other side of the dielectric layer. As the layer is pushed together responsive to force applied, total capacitance as measured across the planes of plate elements varies.

Claims

1. A method for measuring an applied force using a plurality of transducers comprising:

selecting a plurality of transducers;

arranging the plurality of transducers in a two dimensional array;

spacing apart each transducer within the array from every other transducer;

applying a known electric current across first and second terminals defined at spaced apart locations along a resistive layer;

determining a baseline resistance value across the terminals in the absence of the transducer array;

urging the transducer array against the resistive layer with an applied force;

creating at least two contact points between the resistive layer and a first transducer of the array, at least a portion of said current passing from the resistive layer through the first transducer between the first transducer contact points;

creating at least two contact points between the resistive layer and a second transducer of the array, at least a portion of said current passing from the resistive layer through the second transducer between the second transducer contact points; and

measuring a resistance value across the first and second terminals, said resistance value being determinative of the applied force.

2. The method of claim 1 wherein the transducers have a higher conductivity than the resistive layer.

3. The method of claim 1 wherein the step of arranging the plurality of transducers in a two dimensional array include staggering each transducer relative to adjacent transducers within the array.

4. The method of claim 3 wherein the transducers have a substantially rectangular shape.