Browse Prior Art Database

Simulation of Finger Touch Test on a Capacitive Overlay

IP.com Disclosure Number: IPCOM000110855D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Cromar, C: AUTHOR [+2]

Abstract

Disclosed is a technique for touch-testing capacitive overlays used on touch input devices controlling electronic equipment, such as computer monitor screens. It avoids the need for human intervention for touch-testing capacitive overlays and the requirement to find a material with the same capacitance and abrasive nature of a human finger for mechanical finger solutions.

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Simulation of Finger Touch Test on a Capacitive Overlay

      Disclosed is a technique for touch-testing capacitive overlays
used on touch input devices controlling electronic equipment, such as
computer monitor screens.  It avoids the need for human intervention
for touch-testing capacitive overlays and the requirement to find a
material with the same capacitance and abrasive nature of a human
finger for mechanical finger solutions.

      Various technologies are employed for touch input devices of
computer displays, one of which is the use of a capacitive effect.
When the operator's finger comes in contact with the overlay, the
change in capacitance can be detected and the position of the finger
determined.  Functional testing of such overlays is achieved by
assessing their performance against various touch criteria such as
Accuracy, Repeatability and Speed.  Testing is carried out by simply
touching the overlay in predetermined areas with a finger.  Speed
testing is a problem with human operators because the finger must be
moved across the overlay at a precise speed.  Further difficulties
are encountered during PQRL testing where extreme environmental
conditions make it unsuitable for human testing.  As the overlay may
have a life expectancy of five or more years, extensive testing is
required to simulate such usage.  It is impractical to have human
operators perform such tasks and so a finger simulator is needed.

      An obvious method is to use a dummy finger, which simulates the
capacitance of a human finger, attached to a controllable motor
capable of moving the finger to any active point on the overlay,
lifting the finger up and down to simulate touch or no-touch and scan
at various speeds with the finger in contact with the overlay.  Such
a motor mechanism is complex.  But a more...