U.S. patents available from 1976 to present.
U.S. patent applications available from 2005 to present.

Force sensing semiconductive touchpad

Patent 5943044 Issued on August 24, 1999. Estimated Expiration Date: Icon_subject May 15, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Patent References

3921166

Graphical data entry pad
Patent #: 4079194
Issued on: 03/14/1978
Inventor: Kley

Electronic pressure sensitive transducer apparatus
Patent #: 4314227
Issued on: 02/02/1982
Inventor: Eventoff

Bounceless switch apparatus
Patent #: 4315238
Issued on: 02/09/1982
Inventor: Eventoff

Electronic pressure sensitive force transducer
Patent #: 4489302
Issued on: 12/18/1984
Inventor: Eventoff

Touch sensitive control device
Patent #: 4550221
Issued on: 10/29/1985
Inventor: Mabusth

Digitizer pad
Patent #: 4739299
Issued on: 04/19/1988
Inventor: Eventoff ,   et al.

Digitizer pad
Patent #: 4810992
Issued on: 03/07/1989
Inventor: Eventoff

Position detecting device
Patent #: 4988837
Issued on: 01/29/1991
Inventor: Murakami, et al.

Touch pad machine control
Patent #: 4988982
Issued on: 01/29/1991
Inventor: Rayner, et al.

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Inventors

Assignee

Application

No. 857134 filed on 05/15/1997

US Classes:

345/174, Including impedance detection178/18.01, Position coordinate determination for writing (e.g., writing digitizer pad, stylus, or circuitry)178/18.03, Writing digitizer pad178/18.06Capacitive

Examiners

Primary: Shankar, Vijay

Attorney, Agent or Firm

International Classes

G08C 021/00
G09G 005/00

Abstract

A touchpad assembly and method for providing a signal to a computer indicative of the location and applied pressure of an object touching the touchpad assembly is provided. The touchpad assembly includes X and Y position and pressure sensitive semiconductor resistance sensor layers. The X and Y sensors have a pair of spaced apart X and Y conductive traces running across opposite ends such that a resistance RX connects the pair of X traces and a resistance RY connects the pair of Y traces. The X and Y sensors come into contact at a contact point when an object asserts a pressure on the touchpad. The contact point is connected to each trace by a variable pressure resistance RZ associated with the X and Y sensors and variable position resistances of the X and Y resistances. First and second pair of timing capacitors are connected to respective ones of the pairs of X and Y traces. A microprocessor controls and monitors charging time of the capacitors to determine the position and asserted pressure of the object touching the touchpad.

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