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Instrument for measuring lengths or angles

  • US 5,534,859 A
  • Filed: 09/23/1994
  • Issued: 07/09/1996
  • Est. Priority Date: 10/19/1993
  • Status: Expired due to Fees
First Claim
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1. A linear or angular measuring instrument comprising a capacitance sensor having a linear or curvilinear array of sensor electrodes, a scale facing said sensor and having an array of scale features, switching means for a) connecting first selected ones of the sensor electrodes to first means providing them with electrical signals so that they become part of a first spatially periodic pattern of momentarily transmitting electrodes and b) connecting second selected ones of the sensor electrodes to second means so that they become part of a second spatially periodic pattern of momentarily receiving electrodes, said second means determining a relative position of the sensor along the scale, wherein attribution of a sensor electrode to one of said first or second spatially periodic patterns is controlled by control means adapted to shift said first and said second spatially periodic patterns alternately by increments along said array of sensor electrodes so that the shifts of one spatially periodic pattern take place during the intervals between the shifts of the other spatially periodic pattern, the shifts of the first spatially periodic pattern being thus picked up by said second spatially periodic pattern of momentarily receiving electrodes, such that an electrode can be caused to become both transmitting and receiving during the course of a measurement said first and said second spatially periodic patterns being interleaved along said linear or curvilinear array of juxtaposed momentarily transmitting and receiving electrodes.

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