Patents Assigned to Graphtek, Inc.
  • Patent number: 4277732
    Abstract: A stepping motor driver system includes a switching system which sequentially selects windings of a stepper motor in a predetermined pattern to effect stepping of the rotor of the stepping motor from one "hold" position to the next. The stepping motor drive system sequentially connects a high supply voltage to each of the windings to achieve rapid current buildup in the selected windings and to maintain a predetermined average current in the selected windings. An input circuit responsive to a power control signal electrically disconnects the stepping motor windings from the power supply and electrically connects a low current holding current source to the windings so that a low holding current flows through the selected windings, maintaining a "holding" torque on the rotor at a predetermined stepping position thereof. Low power consumption, rapid frictional damping of mechanical oscillation of the rotor, and elimination of audio hum are thereby attained when the rotor is in a hold position.
    Type: Grant
    Filed: August 3, 1979
    Date of Patent: July 7, 1981
    Assignee: Graphtek, Inc.
    Inventors: Lorenz A. Hittel, Raymond H. Yurcik, Jr.