Control system for inductively controlled multi-phase motor

A printer mechanism comprising:

• (a) a multi-phase stepper motor for controlling the location of a printhead,
• (b) a sensor for providing pulses indicative of rotation of said stepper motor between adjacent phases,
• (c) means responsive to the application of power to said mechanism to energize a predetermined phase of said stepper motor,
• (d) second means to suquentially enable adjacent phases of said stepper motor to cause said printhead to move toward a margin of said printer mechanism, and
• (e) third means responsive to the absence of a pulse from said sensor after a new phase has been enabled to locate said margin.

A printer mechansim comprising:

• (a) a stepper motor coupled to translate a printhead relative to a printing medium, and
• (b) control means for operating said printer mechanism in a print/step sequence, said control means further comprising:
• (i) means for enabling a first phase of said motor while disabling a second phase,
• (ii) means responsive to a logic signal to suppress the decaying current in said second phase, said responsive means including a network connected to maintain a constant voltage across said second phase,
• (iii) a sensor for providing a second signal when said stepper motor has rotated through a predetermined portion of the angle between said second and first phases, and
• (iv) second means responsive to said second signal to enable said second phase while disabling and suppressing the decaying current in said first phase, said second responsive means including a network connected to maintain a constant voltage across said first phase.

A printer mechanism comprising:

• (a) a stepper motor coupled to translate a printhead relative to a printing medium, and
• (b) control means for operating said printer mechanism in a print/step sequence, said control means further comprising:
• (i) means for enabling a first phase of said motor while disabling a second phase,
• (ii) means responsive to a logic signal to supress the decaying current in said second phase, said responsive means including a network connected to maintain a constant voltage across said second phase, and
• (iii) means for enabling said first phase a predetermined time after the occurrence of said logic signal.

A thermal printer mechanism comprising:

• (a) a multiphase stepper motor coupled to control the position of a thermal printhead relative to a printing medium, and
• (b) control means for causing said motor to operate said printhead in a carriage return mode, said control means further comprising:
• (i) means to accelerate said motor to a desired velocity,
• (ii) means to substantially maintain said desired velocity during a portion of said carriage return,
• (iii) means to decelerate said motor,
• (iv) a sensor adapted to provide at least one logic pulse when said stepper motor moves from one detent position to an adjacent detent position, and

A thermal printer mechanism comprising:

• (a) a multiphase stepper motor coupled to control the position of a thermal printhead relative to a printing medium,
• (b) control means for causing said motor to operate said printhead in a carriage return mode, said control means further comprising:
• (i) means to accelerate said motor to a desired velocity,
• (ii) means to substantially maintain said desired velocity during a portion of said carriage return, and
• (iii) means to decelerate said motor, and
• (c) a sensor adapted to provide at least one logic pulse when said stepper motor moves fom one detent position to an adjacent detent position,
• wherein said carriage return is effected by sequentially enabling adjacent phases of said stepper motor, and wherein a timer is initiated at the time of each phase change, the phase changes taking place upon said at least one logic pulse or upon the expiriation of said timer, whichever occurs last.