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Device including selectively actuatable sensors and a multiplexer-demultiplexer for contact-free positional measurement of electronic position indicators

  • US 4,652,821 A
  • Filed: 12/02/1983
  • Issued: 03/24/1987
  • Est. Priority Date: 12/04/1982
  • Status: Expired due to Fees
First Claim
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1. An electronic device for contact-free positional measurement, comprising:

  • a position indicator corresponding to a movable or resting part whose position is to be determined and identified,a plurality of selectively activatable sensors connected in parallel across a power source and carried in a sensor carrier, said position indicator and said sensors being movable with respect to one another such that said position indicator is spacially adjacent individual ones of said sensors sequentially during said movement to electromagnetically sense said position indicator, whereby said sensors sense the position of said position indicator,a multiplexer having a plurality of inputs connected to respective ones of said sensors for serial transfer of their output signals,an evaluation circuit connected to said multiplexer to compare multiplexed signals from said plurality of sensors, andmeans for selectively activating each sensor, said activating means including;

    a demultiplexer having a plurality of outputs,a plurality of active elements connected as switches in series with respective ones of said sensors, each of said active elements having a switch activating input connected to a respective one of said demultiplexer outputs and being turned on to activate its series connected sensor by means of said power source upon receipt of a signal from said respective demultiplexer output,whereby said evaluation circuit determines the position of said position indicator with respect to said plurality of sensors regardless of whether in an idle position or when the electronic device is turned on without pre-calibration, thus insuring unequivocal ascertainment of a position of the position indicator part.

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