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Optical position sensor

  • US 5,973,320 A
  • Filed: 12/10/1997
  • Issued: 10/26/1999
  • Est. Priority Date: 12/25/1996
  • Status: Expired due to Term
First Claim
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1. An optical position sensor which comprises:

  • a light emitting means, a light receiving means, and a rotational disk arranged between the light emitting and light receiving means and formed with a spiral slit encompassing a prescribed angular range, wherein a light emitted from the light emitting means and passed through the spiral slit is received by a light receiving surface of the light receiving means, a position where the light is received on the light receiving surface moves in a radial direction of the rotational disk in accordance with a rotational angle of the rotational disk, thereby producing a sensing output corresponding to the rotational angle of the rotational disk;

    a linearity correction circuit for compensating an output from the light receiving means so as to establish a linearity relationship between the sensing output and the rotational angle of the rotational disk;

    the linearity correction circuit has a memory means for storing a corresponding table in which compensation values are assigned to respective rotational angular positions of the rotational disk and for generating one of the compensation values in response to the output from the light receiving means; and

    the compensation values are obtained by measuring an actual relationship between the rotational angle of the rotational disk and the output of the light receiving means, calculating deviation of the output of the light receiving means from a predetermined linearity relationship between the rotational angle of the rotational disk and the output of the light receiving means, and determining compensation values for eliminating the deviation of the output of the light receiving means at respective rotational angular positions of the rotational disk, whereinthe linearity correction circuit retrieves a compensation value from the memory means based on the output of the light receiving means, and compensates the output of the light receiving means so as to produce the sensing output which has a linearity relationship to the rotational angle of the rotational disk.

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