Browse Prior Art Database

Combination Keypad/ Scale Using Strain Gauge Transducers

IP.com Disclosure Number: IPCOM000107285D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Flowers, DK: AUTHOR [+4]

Abstract

This article describes a device which functions as both a keypad and a weighing scale. It is a single device which can serve both requirements, not simply a repackaging of the two devices. It would be used primarily in supermarkets, where the advantages of smaller footprint and lower cost than separate keypad/scale systems would be attractive.

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Combination Keypad/ Scale Using Strain Gauge Transducers

       This article describes a device which functions as both a
keypad and a weighing scale.  It is a single device which can serve
both requirements, not simply a repackaging of the two devices.  It
would be used primarily in supermarkets, where the advantages of
smaller footprint and lower cost than separate keypad/scale systems
would be attractive.

      The touch surface is supported mechanically by three or more
strain gauge transducers oriented such that the device is sensitive
to applied vertical forces.  Using three or more transducers allows
calculation of touch location and magnitude.

      Touch position is calculated from the transducer signals by
solving a static torque balance equation.  The total weight is
computed by summing the signals from the individual transducers,
possibly after correction for variations in transducer sensitivity.

      The touch surface is recessed slightly in the top cover of the
scale to allow the transducers to lie in the same plane as the touch
surface.  This eliminates moments due to lateral forces as a source
of error in computing the touch position.  It may be desirable to
form the touch surface and sides of the device as one piece to
prevent food or liquids from entering the device around the edges of
the touch surface.  The touch surface could be transparent to allow a
display to be viewed through it.

      All the keys commonly found on...