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Stepping motor control unit and method, printer employing the same, and information recording medium

  • US 6,259,225 B1
  • Filed: 08/05/1999
  • Issued: 07/10/2001
  • Est. Priority Date: 12/10/1997
  • Status: Expired due to Term
First Claim
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1. A stepping motor control unit, comprising:

  • (a) an electromagnet having a plurality of excitable phases;

    (b) a rotor assembly having a plurality of slits formed therein, and a plurality of stable positions, each of which corresponds to a respective one of the plurality of phases of the electromagnet;

    (c) a sensing element that detects the position of the rotor assembly, wherein the plurality of slits are positioned on the rotor assembly such that at least one edge of a given slit is offset by a predetermined angle relative to the sensing element when the rotor assembly is in a corresponding stable position, and wherein the sensing element detects the position of the rotor assembly as it rotates between a first stable position and a second stable position at the predetermined angle before the rotor assembly reaches the second stable position relative to the direction of rotation and outputs a detection signal; and

    (d) a control circuit that selectively controls the excitation of each of the plurality of phases of the electromagnet in response to the detection signal and a corresponding one of a plurality of predetermined step times based on the rotational speed of the rotor assembly, wherein the control circuit excites the phase of the electromagnet corresponding to a third stable position of the rotor assembly at a predetermined time after receiving the detection signal.

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