Title: Capacitive touch-pad devices with dynamic bias

Abstract: A dynamic biasing capacitance is formed between a transmitting electrode and a receiving electrode of a capacitive touch-pad device to couple a portion of the scan voltage signal into the sense node of a voltage comparator circuit, coupled to the receiving electrode, to offset the comparator circuit threshold voltage. The dynamic biasing capacitance may be formed by overlapping portions of the electrodes, with a dielectric layer positioned therebetween, or by the parasitic capacitance between aligned end surfaces of the two electrodes, with the magnitude of the dynamic biasing capacitance being adjusted by variation of interelectrode geometries.

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Inventors: Waldron, Wesley K. (Scotia, NY, US)

Application Number: 799345
Filing Date: 1977-05-23
Publication_date: 1979-01-23
Assignee: General Electric Company (Schenectady, NY)
Primary Class(es): 327/77 327/74, 327/509, 361/280, 361/330
Other Classes:
US Patent Ref:

3826979	Jul, 1974	Steinmann	324/61.
3986110	Oct, 1976	Overall et al.	324/61.
4016490	Apr, 1977	Weckenmann et al.	324/61.

Other Refs:
Primary Examiner: Miller, Jr., Stanley D.
Assistant Examiner: Davis, B. P.
Attorney: Krauss; Geoffrey H., Cohen; Joseph T., Snyder; Marvin