Force sensing polymer piezoelectric transducer array

• US 4,491,760 A
• Filed: 03/29/1983
• Issued: 01/01/1985
• Est. Priority Date: 10/16/1981
• Status: Expired due to Fees

• Current Assignee: The Board Of Trustees Of The Leland Stanford Junior University Stanford Hospital And Clinics (Stanford University)
• Original Assignee: Stanford University
• Inventors: Linvill, John G.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US06/480,025
• Time in Patent Office: 644 Days
• Field of Search: 310/328, 310/339, 310/330-332, 310/800, 310/338, 434/114
• US Class Current: 310/334
• CPC Class Codes: G09B 21/003 using tactile presentation of the information, e.g. Braille displays
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

An electromechanical transducer for the generation of an electric signal in response to a force or motion applied to the tactile surface thereof. The electromechanical transducer comprises a stack of planar sheets of a piezoelectric polymer material, each sheet having two opposed broad flat faces and at least one tactile surface at one longitudinal end, separate electrodes covering portions of each flat face of the sheets in predetermined patterns, terminals electrically connected to said electrodes for passage of said electric signal and means for detecting and amplifying the electric signal generated in response to a force or motion applied to the tactile surface of the transducer.

Claims

1. An electromechanical transducer for the generation of an electric signal in response to a force or motion applied to the tactile surface thereof comprising:

a stack of planar sheets of a piezoelectric polymer material, each sheet having two opposed broad flat faces and at least one tactile surface at one longitudinal end;

separate electrodes covering portions of each flat face of the sheets in predetermined patterns;

terminals electrically connected to said electrodes for passage of said electric signal;

means for detecting and amplifying the electric signal generated in response to a force or motion applied to the tactile surface of the transducer; and

means for connecting the corresponding electrodes of a plurality of the sheets in common, such that the sheet portions between the electrodes will respond as a group to an applied force or motion and wherein said electrodes which are connected in common are separated from adjacent electrodes on the same sheet of the piezoelectric polymer material by providing a pattern of cuts through the piezoelectric polymer material which outline the electrodes such that a force or motion applied to one area of the tactile surface of the electromechanical transducer will result in a generation of an electrical signal substantially only across those electrodes commonly connected to that portion of the piezoelectric polymer material subjected to the force or motion.

2. The electromechanical transducer of claim 1 further comprising means to electrically insulate the plurality of sheet material and electrodes connected in common from adjacent sheet material and electrodes not so connected.

3. The electromechanical transducer of claim 2 wherein said insulation means comprises sheets of polytetrafluoroethylene.

4. The electromechanical transducer of claim 1 wherein the piezoelectric sheet material is polyvinylidenefluoride.

5. The electromechanical transducer of claim 1 wherein said means of detecting and amplifying the electric signal is a MOSFET.

6. The electromechanical transducer of claim 1 wherein said electrodes which are connected in common are so connected in series.

7. The electromechanical transducer of claim 1 wherein said electrodes which are connected in common are so connected in parallel.