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Browse Prior Art Database

Position Transducer Device Using Thick Film Resistor Strain Sensors

IP.com Disclosure Number: IPCOM000117645D
Original Publication Date: 1996-Apr-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 127K

Publishing Venue

IBM

Related People

McLean, JR: AUTHOR [+2]

Abstract

Disclosed is an improved transducer design for touchscreens that currently use cantilever beams with bonded metal-foil strain gages. Reduced transducer costs and associated electronic components are possible. Other potential improvements include higher sensitivity and resolution, better durability and reliability, and more flexible design parameters. These improvements are made possible by the use of thick film resistors as strain gauges versus bonded-foild strain gages.

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Position Transducer Device Using Thick Film Resistor Strain Sensors

      Disclosed is an improved transducer design for touchscreens
that currently use cantilever beams with bonded metal-foil strain
gages.  Reduced transducer costs and associated electronic components
are possible.  Other potential improvements include higher
sensitivity and resolution, better durability and reliability, and
more flexible design parameters.  These improvements are made
possible by the use of thick film resistors as strain gauges versus
bonded-foild strain gages.

      Varieties of Thick Film Resistor (TFR) materials display
piezoresistive characteristics and may consequently be utilized in
sensor applications.  TFR materials are currently used in many sensor
applications, such as automotive air and oil pressure, manifold
vacuum sensors, etc., and other industrial applications.  Thick film
resistor materials composed of ruthenium-based conductive phases are
most popular for these applications because of their high gage
factors, long-term stability, etc..

      Low cost, high operating temperatures, small size, good
mechanical properties, long-term stability, severe environment
compatibility and excellent Temperature Coefficient of Resistance
(TCR) are major advantages of TFRs over bonded metal-foil and
semiconductor sensors.  Also, gage factors (the ratio of change in
resistance to strain) for TFRs are in the 10-20 range as compared to
2-5 for bonded foiled gages, producing much higher sensitivity.

      TFRs are fabricated utilizing the variety of thick-film
processing techniques available.  Consequently, transducers may be
produced at low cost on a large scale.

      These materials may be applied by numerous methods, including
pad-printing, screening, roll-coating, spraying, etc., and
subsequently thermally processed to produce the finished resistor and
electrodes.  Further additional processing to define and/or trim
resistors may be done mechanically (scribing, machining, etc.) laser
trimming, and air-jet abrading.

      Materials...