(12) United States Patent ao) Patent No.: us 6,466,036 Bi
Philipp (45) Date of Patent: Oct. 15,2002
(54) CHARGE TRANSFER CAPACITANCE MEASUREMENT CIRCUIT
(76) Inventor: Harald Philipp, 7 Cirrus Gardens, Hamble Hampshire S031 4RH (GB)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/390,869
(22) Filed: Sep. 7, 1999
Related U.S. Application Data
(60) Provisional application No. 60/109,889, filed on Nov. 25, 1998.
(51) Int. CI.7 G01R 27/26
(52) U.S. CI 324/678; 324/658
(58) Field of Search 324/678, 658,
324/661, 663, 665, 676, 679
(56) References Cited
U.S. PATENT DOCUMENTS
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4,054,833 A * 10/1977 Brieler 324/679
4,806,846 A 2/1989 Kerber 324/678
4,977,480 A * 12/1990 Nishihara 73/724 X
5,329,239 A * 7/1994 Kindermann et al 324/678
5,343,157 A * 8/1994 Deschamps 324/678
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5,705,807 A * 1/1998 Throngnumchai et al. .. 250/214
P
5,726,581 A * 3/1998 Vranish 324/688
5,730,165 A 3/1998 Philipp 137/1
6,188,228 Bl * 2/2001 Philipp 324/658
6,242,927 Bl * 6/2001 Adams et al 324/664
6,278,283 Bl * 8/2001 Tsugai 324/678
OTHER PUBLICATIONS
"Capacitive Sensors and Sensing Theory," Product Catalog, Gordon Products, Inc., Brookfield, CT, USA, Oct. 1997.*
* cited by examiner
Primary Examiner—N. Le
Assistant Examiner—T. R. Sundaram
(74) Attorney, Agent, or Firm—David Kiewit
(57) ABSTRACT
Pulse circuits for measuring the capacitance to ground ol a plate may be used in control equipment to provide an indication ol the proximity ol a person or object to be sensed. Pulse circuits are disclosed that are made Irom sets ol three or more electrical switching elements arranged so that each ol the switching elements has one side electrically connected to either a supply voltage or to an electrical ground. These arrangements are compatible with existing integrated circuit labrication technology. In addition, the circuitry can be configured as a proximity sensing switch that requires only a two wire connection to a host apparatus.
39 Claims, 14 Drawing Sheets
