Step motor driving circuit
First Claim
1. A step motor driving circuit for a step motor comprising:
- (a) A-phase and B-phase exciting windings, said A-phase and B-phase windings being independent of each other;
(b) first current selection means for selectively applying currents having a first current value, a second current value or zero value to said A-phase windings, said first and second exciting currents being of a predetermined ratio, said first being larger than said second, said first current selection means varying said currents between said values with a gradually changing waveform;
(c) second current selection means for selectively applying currents having said first current value, said second current value or zero value to said B-phase windings, said second current selection means varying said currents between said values with a gradually changing waveform; and
(d) control means for applying control signals to said first and second current selection means in a four state sequence of four successive control signal groups to cause the latter to excite said A-phase and B-phase windings in the following sequence of states;
excitation of one of said phase windings with a current of said first current value and the other of said phase windings with a current of zero value;
excitation of said one winding with a current of said first current value and the other winding with a current of said second current value;
excitation of both phase windings with currents of said first current value;
excitation of said one winding with a current of said second current value and excitation of said other winding with a current of said first current value, whereby each successive four state excitation constitutes one step of said step motor.
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Accused Products
Abstract
A step motor driving circuit having A-phase and B-phase exciting windings which are independently supplied with exciting current in a sequence of four states per step of the step motor. The driving circuit is capable of applying a large or a small current to each phase winding and the currents are applied in a sequence to result in a trapezoidal shaped exciting current. During a first state only one phase is excited and it is excited with the large current. During the second state the one phase is excited with the large current and the other phase with the small current. During the third state both phases are excited with large currents. During the fourth state the one phase is excited with the small current and the other phase with the large current.
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Citations
10 Claims
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1. A step motor driving circuit for a step motor comprising:
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(a) A-phase and B-phase exciting windings, said A-phase and B-phase windings being independent of each other; (b) first current selection means for selectively applying currents having a first current value, a second current value or zero value to said A-phase windings, said first and second exciting currents being of a predetermined ratio, said first being larger than said second, said first current selection means varying said currents between said values with a gradually changing waveform; (c) second current selection means for selectively applying currents having said first current value, said second current value or zero value to said B-phase windings, said second current selection means varying said currents between said values with a gradually changing waveform; and (d) control means for applying control signals to said first and second current selection means in a four state sequence of four successive control signal groups to cause the latter to excite said A-phase and B-phase windings in the following sequence of states;
excitation of one of said phase windings with a current of said first current value and the other of said phase windings with a current of zero value;
excitation of said one winding with a current of said first current value and the other winding with a current of said second current value;
excitation of both phase windings with currents of said first current value;
excitation of said one winding with a current of said second current value and excitation of said other winding with a current of said first current value, whereby each successive four state excitation constitutes one step of said step motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification