System for driving a direct-current motor in synchronism with an external signal

Claim 5

The system as recited in claim 1, wherein said first control circuit comprises: a switching circuit switched between a first and a second state, said switching circuit being switched to said first state in response to each pulse of said synchronizing signal and to said second state in response to each pulse of said rotor position signal; a driving circuit for causing the flow of current from said DC power supply through said motor in the forward direction when said switching circuit is switched to said first state; and a retarding circuit for causing the flow of current from said DC power supply through said motor in the reverse direction when said switching circuit is switched to said second state.

Claim 6

The system as recited in claim 2, wherein said driving circuit and said retarding circuit of said first control circuit share a flip-flop circuit, said flip-flop circuit being switched to a first stable state when said switching circuit has assumed said first state and to a second stable state when said switching circuit has assumed said second state, whereby the flow of current from said DC power supply is caused through said motor in the forward direction when said flip-flop circuit has assumed said first stable state, and in the reverse direction when said flip-flop circuit has assumed said second stable state.

Claim 7

The system as recited in claim 3, wherein said second control circuit comprises: a second flip-flop circuit shared by said first and said second sensing circuits, said second flip-flop circuit being alternately switched between a third and a fourth stable state in response to each pulse of said synchronizing signal and said rotor position siGnal; a first switching element included in said first sensing circuit, said first switching element being rendered conductive when triggered by said synchronizing signal while said second flip-flop circuit is in said second stable state; a second switching element included in said second sensing circuit, said second switching element being rendered conductive when triggered by said rotor position signal while the first mentioned flip-flop circuit is in said second stable state; and a third flip-flop circuit switched between a fifth and a sixth stable state, said third flip-flop circuit being switched to said fifth stable state in response to the conduction of said first switching element and to said sixth stable state in response to the conduction of said second switching element; whereby when said third flip-flop circuit is switched to said fifth stable state, said switching circuit of said first control circuit being electrically disconnected from the first mentioned flip-flop circuit to maintain the latter in said first stable state, the normal electrical relationship between said switching circuit and the first mentioned flip-flop circuit being regained when said third flip-flop circuit is switched to said sixth stable state.

Claim 8

The system as recited in claim 4, wherein each of said first and said second switching elements is a silicon-controlled rectifier.

Claim 9

The system as recited in claim 5, wherein said synchronizing signal is delivered via a first delay circuit to said second flip-flop circuit and directly to the gate terminal of said silicon-controlled rectifier employed in place of said first switching element, and wherein said rotor position signal is delivered via a second delay circuit to said second flip-flop circuit and directly to the gate terminal of said silicon-controlled rectifier employed in place of said second switching element.

Claim 10

The system as recited in claim 1, further comprising means for permitting said motor to rotate in one direction only.

Claim 11

The system as recited in claim 7, wherein said means for permitting said motor to rotate in one direction only comprises: a substantially annular enclosure loosely mounted on the shaft of said motor, said enclosure being immovably supported by a stationary part of said motor so that said shaft is free to rotate relative to said enclosure, and said enclosure having a plurality of cam grooves formed therein which are open to the circumference of said shaft; at least one ball accommodated in each of said cam grooves of said enclosure; a ring loosely mounted on said shaft of said motor so as to be rotatable relative to each other; a pair of stops extending from said ring into each of said cam grooves to limit the motion of said ball along the circumference of said shaft, in such a manner that said shaft is permitted to rotate in one direction only and is prevented from rotation in the other direction as then said ball in each of said cam grooves is thereby urged against the circumference of said shaft with the start of rotation thereof in said other direction; and means for turning said ring between a first and a second predetermined angular position to vary the position of said ball relative to each of said cam grooves, whereby said shaft is permitted to rotate in said other direction and is prevented from rotation in said one direction as said ring is turned from said first to said second predetermined angular position.

Claim 12

The system as recited in claim 8, wherein said means for turning said ring comprises a spring member urging said ring to said first predetermined angular position, and solenoid means effective to turn said ring to said second predetermined angular position against the force of said spring member when energized.