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Position detector for synchronizing operation of a recording device with that of a carriage in a recording apparatus

  • US 5,541,508 A
  • Filed: 04/19/1994
  • Issued: 07/30/1996
  • Est. Priority Date: 04/28/1993
  • Status: Expired due to Fees
First Claim
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1. A position detector for a recording apparatus, said position detector comprising:

  • a carriage which is reciprocally moved for a recording operation;

    recording means, carried on said carriage, for performing a recording operation in synchronization with the movement of said carriage;

    a magnetic recording medium on which a magnetic pattern, recorded at a prescribed pitch, is formed in a longitudinal direction;

    a magnetoresistive element arranged so as to move along the magnetic pattern and having a resistance value which varies depending upon reading of the magnetic pattern;

    a constant-current circuit for passing a constant current through said magnetoresistive element;

    an amplifier for amplifying the constant current and delivering an amplified output signal externally of said apparatus, said amplifier having an output terminal for varying an offset voltage of the amplified output signal;

    sampling means for sampling the amplified output signal of said amplifier;

    an A/D converter for A/D-converting a signal sampled by said sampling means and for producing an output value;

    a controller, to which an output value from said A/D converter is applied as an input, for calculating at least the offset voltage of the amplified output signal of said amplifier from the output value of said A/D converter, and setting an offset voltage corresponding to a desired offset voltage;

    a D/A converter for D/A-converting the offset voltage value set by said controller and outputting the converted offset voltage value to an input terminal of said amplifier; and

    pulse generating means for generating a pulse output signal based on the amplified output signal, which is used to synchronize the recording operation of said recording means with respect to the movement of said carriage.

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