Browse Prior Art Database

Failure Detection of Capacitive Sensor

IP.com Disclosure Number: IPCOM000045693D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Barsotti, RH: AUTHOR

Abstract

Failure-detection circuitry is added to a capacitive sense circuit to detect failure of a sensor.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Failure Detection of Capacitive Sensor

Failure-detection circuitry is added to a capacitive sense circuit to detect failure of a sensor.

A capacitive sense circuit comprises an oscillator 10 and a driver 11 which amplifies the oscillator output and supplies it to a capacitive sensor 12. The sensor provides outputs to filter rectifiers 13 and 14, the sensor measurement comprising the relative values of the outputs. The filtered and rectified relative outputs are supplied to a differential amplifier 14 to provide a sense output voltage.

The failure detection circuitry comprises differential amplifier 15 and window comparator 16. The relative outputs from the capacitive sensor are summed and supplied as one input to differential amplifier 15. The other input is a reference voltage. Difference voltage between the two inputs is supplied to window comparator 16. lf the difference voltage becomes too large, the window comparator generates a capacitive sensor fail output signal.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text objects]