Browse Prior Art Database

Touch-Screen Device Using Bending/Torsion Member

IP.com Disclosure Number: IPCOM000102042D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 66K

Publishing Venue

IBM

Related People

Gallarelli, P: AUTHOR

Abstract

A touch-screen device is described which uses members in bending and torsion as sensing elements for determining touch position. The device, in conjunction with suitable operational software, would give any computer display touch-screen capability.

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Touch-Screen Device Using Bending/Torsion Member

       A touch-screen device is described which uses members in
bending and torsion as sensing elements for determining touch
position.  The device, in conjunction with suitable operational
software, would give any computer display touch-screen capability.

      At the heart of the touch-screen device are two sensing
elements that measure touch force, bending moment and torsion using
strain gages.  Referring to Figs. 1 and 2, the display 10 is placed
on a carriage 12 that rides on linear bearings.  As a touch-force is
applied, its magnitude is measured by the touch-force sensor 16.  At
the same time, torque and bending moment are measured by the torsion
and bending sensors.  Torque and bending results are used to
calculate "X" and "Y" touch positions, respectively.  The touch-force
value is required during these calculations to normalize for varying
touch-force magnitudes.  Position calculations also include
multiplication by scaling constants having a magnitude dependent upon
factors such as strain-gage sensitivity, sensor material, amplifier
gain, monitor size, etc.  These constants would be determined by an
initialization routine that sets their value to match user-selected
screen boundaries.  The linear relationship between touch force and
strain makes all touch positions within the boundaries proportional.

      Fig. 3 shows the Wheatstone bridge electrical circuit used for
amplifying strain-gage...