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US 4,294,552 AGranted
Bidirectional ribbon drive control for printers
AssigneeInternational Business Machines Corporation
InventorJohn Mako
Life of this patent
Estimating the term…
Abstract
A printer having an ink ribbon with a bidirectional ribbon drive in which a pair of stepper motors have their windings cross-coupled so that a drag current flows through one stepper motor to apply drag torque to the ribbon when the other stepper motor is operated for driving.
Claims7
A printer for printing characters on a print medium via an ink ribbon having a reversible ribbon drive for feeding said ribbon during printing comprising:
- a pair of ribbon spools,
- first and second stepper motors connected separately to said spools,
- said first and second stepper motors each including windings for the operation thereof,
- control circuitry for operating said stepper motors such that when one stepper motor is driven, the other stepper motor is dragged,
- said control circuitry comprising a first set of motor drivers connected to said windings of said first stepper motor,
- a second set of drivers connected to said windings of said second stepper motor,
- means for applying phase sequencing signals to either said first or second set of drivers for driving only one of said stepper motors,
- and cross-coupling connections between said windings of said first and said second stepper motors forming a current path for drag current between said windings of one stepper motor when the other stepper motor is driving.
5 more elements
Dependencies are inferred from the claim text.