Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Capacitive Switch

IP.com Disclosure Number: IPCOM000077370D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Jensen, DF: AUTHOR [+3]

Abstract

A pneumatic to electrical transducer in the form of a capacitive switch is provided, which consists of a variable capacitance device responsive to input pressure changes to achieve one of two digital capacitance values.

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

Capacitive Switch

A pneumatic to electrical transducer in the form of a capacitive switch is provided, which consists of a variable capacitance device responsive to input pressure changes to achieve one of two digital capacitance values.

The drawing shows a top view, a side view and a schematic representation of capacitive switch 10. A pair of plates 11 and 12 are deposited on substrate 21. The plates are connected by deposited patterns to connection points 13 and 14, respectively.

In cross-section, substrate 21 supports deposited plates 11 and 12 as well as connection points 13 and 14. Connection points 13 and 14 are connected to plates 11 and 12 by dip soldering, forming solder points 23. An insulating layer 24 in the order of 1 mil thickness or less, enables movable plate 26 to be placed in close proximity to fixed plates 11 and 12. This optimizes the maximum capacitance value.

Movable plate 26 is separated from fixed plates 11 and 12 by cavity 27, which is at atmospheric pressure supplied through tube 30. Diaphragm membrane 25 supports movable plate 26. Diaphragm 25 is a highly compliant element which deflects when subjected to small pressure differentials in the order of 1 psig. This pressure is supplied through tube 31 to cavity 28, to cause diaphragm 25 to displace movable plate 26 into close proximity with fixed plates 11 and 12, thus increasing the capacitance between terminals 13 and 14.

1

Page 2 of 2

2

[This page contains 2 pictures or other non-text o...