Control system for stepping motors

Claim 3

The method of operating a multi-phase motor as defined in claim 1 including the additional step of: energizing at least a predetermined one of said multi-phase windings concurrently with the energization of at least said first of the multi-phase windings to compensate for external unbalanced forces.

Claim 6

The method of operating a four-phase stepping motor as defined in claim 3 including the additional step of: selectively energizing one of the phases D and C concurrent with the energization of phases B and C to generate a compensating torque capable of overcoming the effects of external unbalanced torque.

Claim 7

A control system for use with a stepping motor having multi-phase windings for operating said motor between a pair of prescribed limit positions comprising, a physical stop operatively arranged at each of said limit positions to prevent the rotor of said motor from attaining the rest position beyond the limit position toward which it is being moved by an applied torque, first means coupled to at least a first of said multi-phase windings for causing a high level current to flow therethrough, said high level current applying an accelerating torque to said rotor to cause it to move from one of its limIt positions toward its opposite limit position, the stator housing of said motor being oriented such that the torque generated by said high level current diminishes as the rotor approaches the midpoint of the travel between said limit positions and is at a null substantially at said midpoint, said last-mentioned torque increasing in a reverse direction beyond said midpoint whereby the velocity of said rotor is diminished and approaches zero as the rotor approaches said opposite limit position, said first means terminating said high level current flow substantially at the time said rotor attains said zero velocity condition, second means coupled to at least a second of said multi-phase windings and being effective upon the termination of said high level current for causing a low level current to flow therethrough, said low level current applying an accelerating torque to said rotor in a direction to cause it to move toward the rest position beyond said opposite limit position and to reach said last mentioned position and to hold it there.

Claim 8

A control system for use with a stepping motor having multi-phase windings for operating said motor between a pair of prescribed limit positions comprising, a physical stop operatively arranged at each of said limit positions to prevent the rotor of said motor from attaining the rest position beyond the limit position toward which it is being moved by an applied torque, first means coupled to at least a first of said multi-phase windings for causing a high level current to flow therethrough, said high level current applying an accelerating torque to said rotor to cause it to move from one of its limIt positions toward its opposite limit position, the stator housing of said motor being oriented such that the torque generated by said high level current diminishes as the rotor approaches the midpoint of the travel between said limit positions and is at a null substantially at said midpoint, said last-mentioned torque increasing in a reverse direction beyond said midpoint whereby the velocity of said rotor is diminished and approaches zero as the rotor approaches said opposite limit position, said first means terminating said high level current flow substantially at the time said rotor attains said zero velocity condition, second means coupled to at least a second of said multi-phase windings and being effective upon the termination of said high level current for causing a low level current to flow therethrough, said low level current applying an accelerating torque to said rotor in a direction to cause it to move toward the rest position beyond said opposite limit position and to reach said last mentioned position and to hold it there.

Claim 9

A control system as defined in claim 5 wherein said rotor is coupled to a gate member, said gate member being operatively arranged to contact said physical stops at said limit positions whereby the motion of said member is confined between said stops.

Claim 10

A control system as defined in claim 6 wherein said stator housing is oriented such that the null point of the torque generated by said high level current is displaced a predetermined angular distance from the midpoint of the travel limits to overcome the effects of the external torque on said gate member.

Claim 11

A control system as defined in claim 6 wherein said second means is further adapted to cause a low level current to flow through at least a predetermined one of said multi-phase windings concurrent with the flow of said high level current through at least said first of said windings, in order to compensate for external forces which cause an unbalanced torque to be impressed upon said gate member.

Claim 12

A control system for use with a stepping motor having four phase windings designated respectively A, B, C and D for operating said motor between a pair of prescribed limits comprising, a physical stop operatively arranged at each of said limits to prevent the rotor of said motor from attaining the rest position beyond the limit toward which it is being moved by an applied torque, first driver means for causing above-rated current to flow through said B and C windings, said last-mentioned current applying an accelerating torque to said rotor to cause it to move from one of said limits toward its opposite limit, the stator housing of said rotor being oriented such that the torque generated by said current flow through windings B and C diminishes as the rotor approaches the midpoint of travel between said limits and reaches a null substantially at said midpoint, said last-mentioned torque increasing in a reverse direction beyond said null whereby the velocity of said rotor is diminished and approaches zero as the rotor approaches said opposite limit, said first driver means terminating said above-rated current flow through windings B and C substantially at the time of attainment of said zero velocity condition, second and third driver means capable of causing rated currents to flow through the respective pairs of winding, A, B, and C, D, said rated currents generating oppositely directed torques, means responsive to the desired direction of motor operation and effective upon the termination of said above-rated current through windings B and C for selectively activating one of said second and third driver means, the selected one of said last-mentioned means causing a torque to be generated in the proper direction to move said rotor toward the rest position beyond said opposite limit and to reach said opposite limit and to maintain it at said limit.

Claim 13

A control system for use with a stepping motor having four phase windings designated respectively A, B, C and D for operating said motor between a pair of prescribed limits comprising, a physical stop operatively arranged at each of said limits to prevent the rotor of said motor from attaining the rest position beyond the limit toward which it is being moved by an applied torque, first driver means for causing above-rated current to flow through said B and C windings, said last-mentioned current applying an accelerating torque to said rotor to cause it to move from one of said limits toward its opposite limit, the stator housing of said rotor being oriented such that the torque generated by said current flow through windings B and C diminishes as the rotor approaches the midpoint of travel between said limits and reaches a null substantially at said midpoint, said last-mentioned torque increasing in a reverse direction beyond said null whereby the velocity of said rotor is diminished and approaches zero as the rotor approaches said opposite limit, said first driver means terminating said above-rated current flow through windings B and C substantially at the time of attainment of said zero velocity condition, second and third driver means capable of causing rated currents to flow through the respective pairs of winding, A, B, and C, D, said rated currents generating oppositely directed torques, means responsive to the desired direction of motor operation and effective upon the termination of said above-rated current through windings B and C for selectively activating one of said second and third driver means, the selected one of said last-mentioned means causing a torque to be generated in the proper direction to move said rotor toward the rest position beyond said opposite limit and to reach said opposite limit and to maintain it at said limit.

Claim 14

A control system as defined in claim 9 wherein said second and third driver mEans are adapted to cause current flow respectively in windings D and C concurrent with the flow of said above-rated current through windings B and C, said selected one of said second and third driver means thereby causing a torque to be generated which will compensate for external unbalanced forces operating upon said rotor.

Claim 15

A control system as defined in claim 10 wherein said second driver means is coupled directly to said winding A and by way of a first diode to winding B, and said third driver means is coupled directly to said winding D and by way of a second diode to winding C, the energization of windings B and C by said third driver means reverse-biasing said first and second diodes thereby precluding said second and third driver means from supplying current respectively to windings B and C while said third driver means is active.

Claim 16

A control system as defined in claim 11 wherein said means for selectively activating said second and third driver means comprises amplifier means adapted to receive signals from an external source and being responsive to said signals for activating and controlling appropriate ones of said first, second, and third driver means.

Claim 17

A control system as defined in claim 12 wherein said amplifier means comprise a plurality of current amplifying devices, a first and second of said devices being normally in opposite states of conduction, said signals from said external source being applied to said first device and determining at any given time the respective conductive states of said devices, said first and second devices being coupled respectively to said second and third driver means, the selective actuation of one of the latter driver means being a function of the conductive states of said last-mentioned devices, a third and fourth of said devices, resistive/capacitive means coupling said third and fourth devices respectively to said first and second devices, the conductive states of said former devices being dependent upon the conductive states of the latter devices, a fifth of said devices coupled in common to said third and fourth devices and being normally biased to nonconduction as a result of the conduction of either one of said last-mentioned devices, a resistive/capacitive network coupling a sixth of said devices to said fifth device, said sixth device being normally biased to a conductive state, a seventh of said devices coupled to said sixth device and having a conducting state opposite to and controlled by the state of said sixth device, said seventh device being coupled to said first driver means, the switching of conductive states in said first and second devices in response to said external signal causing a transient condition associated with and limited in time by said resistive/capacitive means wherein both said third and fourth devices are driven to a nonconducting state, said fifth device assuming a conducting state during the period of said transient condition, the cessation of said condition effected by the conduction of one of said third or fourth devices terminating the conduction of said fifth device, said sixth device being driven to a nonconducting state in response to said last-mentioned termination of conduction and remaining in this state for a period determined by the time-constant of said resistive/capacitive network associated therewith, said seventh device being biased to a conducting state during said period, said first driver means being activated in response to said conducting state in said seventh device and remaining activated until the resumption of conduction by said sixth device.

Claim 18

A control system as defined in claim 13 wherein said current amplifying devices are transistors.

Claim 19

A control system for use with a stepping motoro having multi-phase windings comprising, a plurality of current driver means coupled respectively to predetermined ones of said windings, amplifier means adapted to receive signals from an exTernal source and being responsive to said signals for acivating and controlling appropriate ones of said driver means, said maplifier means comprising a plurality of current amplifying devices, a first and second of said devices being normally in opposite states of conduction, said signals from said external source being applied to said first device and determining at any given time the respective conductive states of said devices, said first and second devices being coupled respectively to a first and a second of said driver means, the selective actuation of one of the latter driver means being a function of the conductive states of said last-mentioned devices, a third and a fourth of said devices, resistive/acapcitive means coupling said third and fourth devices respectively to said first and second devices, the conductive states of said former devices being dependent upon the conductive states of the latter devices, a fifth of said devices coupled in common to said third and fourth devices and being normally biased to nonconduction as a result of the conduction of either one of said last-mentioned devices, a resistive/capacitive network coupling a sixth of said devices to said fifth device, said sixth device being normally biased to a conductive state, a seventh of said devices coupled to said sixth device and having a conductive state opposite to and controlled by the state of said sixth device, said seventh device being coupled to a third of said driver means, the switching of conductive states in said fist and second devices in response to said external signal causing a transient condition associated with and limited in time by said resistive/capacitive means wherein both said third and fourth devices are driven to a nonconducting state, said fifth device assuming a conducting state during the period of said transient condition, the cessation of said condition effected by the conduction of one of said third or fourth devices terminating the conduction of said fifth device, said sixth device being driven to a nonconducting state in response to said last-mentioned termination of conduction and remaining in this state for a period determined by the time-constant of said resistive/capacitive network associated therewith, said seventh device being biased to a conducting state during said period, said third driver means being activated in response to said conducting state in said seventh device and remaining activated until the resumption of conduction by said sixth device.

Claim 20

A control system for use with a stepping motoro having multi-phase windings comprising, a plurality of current driver means coupled respectively to predetermined ones of said windings, amplifier means adapted to receive signals from an exTernal source and being responsive to said signals for acivating and controlling appropriate ones of said driver means, said maplifier means comprising a plurality of current amplifying devices, a first and second of said devices being normally in opposite states of conduction, said signals from said external source being applied to said first device and determining at any given time the respective conductive states of said devices, said first and second devices being coupled respectively to a first and a second of said driver means, the selective actuation of one of the latter driver means being a function of the conductive states of said last-mentioned devices, a third and a fourth of said devices, resistive/acapcitive means coupling said third and fourth devices respectively to said first and second devices, the conductive states of said former devices being dependent upon the conductive states of the latter devices, a fifth of said devices coupled in common to said third and fourth devices and being normally biased to nonconduction as a result of the conduction of either one of said last-mentioned devices, a resistive/capacitive network coupling a sixth of said devices to said fifth device, said sixth device being normally biased to a conductive state, a seventh of said devices coupled to said sixth device and having a conductive state opposite to and controlled by the state of said sixth device, said seventh device being coupled to a third of said driver means, the switching of conductive states in said fist and second devices in response to said external signal causing a transient condition associated with and limited in time by said resistive/capacitive means wherein both said third and fourth devices are driven to a nonconducting state, said fifth device assuming a conducting state during the period of said transient condition, the cessation of said condition effected by the conduction of one of said third or fourth devices terminating the conduction of said fifth device, said sixth device being driven to a nonconducting state in response to said last-mentioned termination of conduction and remaining in this state for a period determined by the time-constant of said resistive/capacitive network associated therewith, said seventh device being biased to a conducting state during said period, said third driver means being activated in response to said conducting state in said seventh device and remaining activated until the resumption of conduction by said sixth device.

Claim 21

A control system as defined in claim 15 wherein each of said first and second driver means is coupled directly to at least one of said windings and by way of a diode to at least another of said windings, said diode being poled to prevent current flow through said last-mentioned winding provided by said first and second driver means when said winding is energized by said third driver means.