Stepping motor driver

Claim 2

Control circuitry for exciting the field windings of a multiphase stepping motor, comprising a driver circuit for supplying energizing currents to said field windings in a predetermined sequential switching format, so that each field winding is energized during certain preselected time increments of said switching format and de-energized during certain other preselected time increments of said switching format; a power supply for said driver circuit; said driver circuit including a plurality of switching circuits corresponding in number to the number of stepping phases of said motor, said switching circuits coupled in pairs to respective pairs of said field windings constituting respective phases of said motor and each of said switching circuits including in series one of said windings, two series connected diodes and a phasing switch, all in the order recited, and means associated with each respective pair of switching circuits for storing energy from said power supply during energization of one of the associated field windings and for supplying the stored energy in the form of additional energizing current to said one associated field winding at the conclusion of its normal energization interval, and for storing energy from the collapsing magnetic field of said one associated field winding upon de-energization thereof and for supplying the last-named stored energy in the form of additional energizing current to the other associated field windings at the conclusion of its normal energization interval, said storing and supplying means comprising a capacitor interconnecting each pair of said switching circuits, and wherein each of said switching circuits includes one of said phasing switches responsive to said switching format to open and close circuits containing respective field windings through said capacitor to produce said storing and supplying operations during said intervals.

Claim 3

Control circuitry for exciting the field windings of a multiphase stepping motor, comprising a driver circuit for supplying energizing currents to said field windings in a predetermined sequential switching format, so that each field winding is energized during certain preselected time increments of said switching format and de-energized during certain other preselected time increments of said switching format; a power supply for said driver circuit; said driver circuit including a plurality of switching circuits corresponding in number to the number of stepping phases of said motor, said switching circuits coupled in pairs to respective pairs of said field windings constituting respective phases of said motor, and means associated with each respective pair of switching circuits for storing energy from said power supply during energization of one of the associated field windings and for supplying the stored energy in the form of additional energizing current to said one associated field winding at the conclusion of its normal energization interval, and for storing energy from the collapsing magnetic field of said one associated field winding upon de-enerization thereof and for supplying the last-named stored energy in the form of additional energizing current to the other associated field windings at the conclusion of its normal energization interval, said means for storing and supplying comprising a capacitor interconnecting each pair of said switching circuits, and wherein each of said switching circuits includes switch means responsive to said switching format to open and close circuits containing the respective field windings through said capacitor to produce said storing and supplying operations during said intervals, and switch means comprising a transistor for each switching circuit, and wherein is further provided in each switching circuit first diode means for protecting said transistor from reverse voltage surges in said windings and second diode means to prevent oscillation of a completed circuit containing said capacitor and associated field windings.

Claim 4

Control circuitry for exciting the field windings of a multiphase stepping motor, comprising a driver circuit for supplying energizing currents to said field windings in a predetermined sequential switching format, so that each field winding is energized during certain preselected time increments of said switching format and de-energized during certain other preselected time increments of said switching format; a power supply for said driver circuit; said driver circuit including a plurality of switching circuits corresponding in number to the number of stepping phases of said motor, said switching circuits coupled in pairs to respective pairs of said field windings constituting respective phases of said motor, and means associated with each respective pair of switching circuits for storing energy from said power supply during energization of one of the associated field windings and for supplying the stored energy in the form of additional energizing current to said one associated field winding at the conclusion of its normal energization interval, and for storing energy from the collapsing magnetic field of said one associated field winding upon de-enerization thereof and for supplying the last-named stored energy in the form of additional energizing current to the other associated field windings at the conclusion of its normal energization interval, said means for storing and supplying comprising a capacitor interconnecting each pair of said switching circuits, and wherein each of said switching circuits includes switch means responsive to said switching format to open and close circuits containing the respective field windings through said capacitor to produce said storing and supplying operations during said intervals, and switch means comprising a transistor for each switching circuit, and wherein is further provided in each switching circuit first diode means for protecting said transistor from reverse voltage surges in said windings and second diode means to prevent oscillation of a completed circuit containing said capacitor and associated field windings.

Claim 5

The invention according to claim 2 wherein the controllable current path of said transistor is connected in series circuit with said first diode means, said second diode means, the respective field winding, and said power supply in each switching circuit; and wherein said capacitor is connected from the junction of said first and said second diode means in one switching circuit to the junction of said first and said second diode means in the other switching circuit for a respective pair of said switching circuits; and wherein the end of the controllable current path of the transistor opposite that to which said first diode means is connected is coupled to the corresponding end of the transistor in the other switching circuit of that pair and to a point of reference potential.

Claim 6

Apparatus for controlling the excitation of windings of a multiphase stepping motor for equal intervals of time according to a predetermined sequential excitation format, said format characterized by the excitation of certain windings during intervals in which certain other windings are unexcited and vice versa, so that the windings form complementary pairs; said apparatus comprising a plurality of non-inducive phase activation circuits, each associated with a respective one of said windings; a d-c power supply coupled to all of said activation circuits; said activation circuits coupled together in pairs and each containing in series one of said windings, two series connected diodes and a phasing switch all in the order recited, said phasing switches including active transistor elements arranged to undergo flip-flop operaTion in response to said excitation format, so that first the activation circuit associated with one winding and then the activation circuit associated with the other winding of a complementary pair supply energizing current to the respective winding from said d-c power supply; and one electrical energy storage means connected between each pair of activation circuits for storing electrical energy from said power supply and from the collapsing magnetic field of the de-energized winding during portions of the excitation format and for supplying stored energy to the windings in the proper sequence during other portions of the excitation format to increase the average current to said windings over a substantial number of steps of the stepping motor relative to the value of average current to said windings in the absence of energy storage.

Claim 7

Apparatus for controlling the excitation of windings of a multiphase stepping motor for equal intervals of time according to a predetermined sequential excitation format, said format characterized by the excitation of certain windings during intervals in which certain other windings are unexcited and vice versa, so that the windings form complementary pairs; said apparatus comprising a plurality of non-inducive phase activation circuits, each associated with a respective one of said windings; a d-c power supply coupled to all of said activation circuits; said activation circuits coupled together in pairs and each containing in series one of said windings, two series connected diodes and a phasing switch all in the order recited, said phasing switches including active transistor elements arranged to undergo flip-flop operaTion in response to said excitation format, so that first the activation circuit associated with one winding and then the activation circuit associated with the other winding of a complementary pair supply energizing current to the respective winding from said d-c power supply; and one electrical energy storage means connected between each pair of activation circuits for storing electrical energy from said power supply and from the collapsing magnetic field of the de-energized winding during portions of the excitation format and for supplying stored energy to the windings in the proper sequence during other portions of the excitation format to increase the average current to said windings over a substantial number of steps of the stepping motor relative to the value of average current to said windings in the absence of energy storage.

Claim 8

A driver circuit for the windings of a step motor having a plurality of complementary stepping phases, comprising a separate transistor switching circuit for each phase, connected to the respective winding associated with that phase, and each said transistor switching circuit including a transistor phasing switch and two diodes connected in series between said respective winding and said phasing switch, each said switching circuit effective, when energized, to excite said respective winding for a predetermined interval of time, one separate capacitive electrical energy storing means connected between each pair of switching circuits connected to a pair of complementary windings, and means connecting the switching circuits associated with a pair of complementary windings together via the respective electrical energy storing means associated with those switching circuits such that upon energization in alternation of each said pair of switching circuits, the electrical energy storing means connected thereto stores energy from the collapsing magnetic field of the winding whose excitation has been removed and supplies the stored energy to the complementary winding in or contiguous with its next interval of excitation.

Claim 9

A driver circuit for the windings of a step motor having a plurality of complementary stepping phases, comprising a separate transistor switching circuit for each phase, connected to the respective winding associated with that phase, and each said transistor switching circuit including a transistor phasing switch and two diodes connected in series between said respective winding and said phasing switch, each said switching circuit effective, when energized, to excite said respective winding for a predetermined interval of time, one separate capacitive electrical energy storing means connected between each pair of switching circuits connected to a pair of complementary windings, and means connecting the switching circuits associated with a pair of complementary windings together via the respective electrical energy storing means associated with those switching circuits such that upon energization in alternation of each said pair of switching circuits, the electrical energy storing means connected thereto stores energy from the collapsing magnetic field of the winding whose excitation has been removed and supplies the stored energy to the complementary winding in or contiguous with its next interval of excitation.

Claim 10

In a multi-phase step motor having windings of phases 1 to n, where n is an even number, means for energizing said phases always simultaneously in adjacent pairs and sequentially selecting the pairs timewise to accomplish a complete sequential scan of all the phases while only maintaining adjacent pairs energized, a terminal connected between a voltage source and a reference point, parallel circuits extending between said terminal and said reference point, each of said parallel circuits including in series one of said windings, two series connected diodes poled to be conductive of current between said terminal and said reference point, and a phasing switch, all in the order recited, and a separate storage capacitor connected between the junctions of the series connected diodes of all pairs of said windings numbered by numbers separated by unity.

Claim 11

In a multi-phase step motor having windings of phases 1 to n, where n is an even number, means for energizing said phases always simultaneously in adjacent pairs and sequentially selecting the pairs timewise to accomplish a complete sequential scan of all the phases while only maintaining adjacent pairs energized, a terminal connected between a voltage source and a reference point, parallel circuits extending between said terminal and said reference point, each of said parallel circuits including in series one of said windings, two series connected diodes poled to be conductive of current between said terminal and said reference point, and a phasing switch, all in the order recited, and a separate storage capacitor connected between the junctions of the series connected diodes of all pairs of said windings numbered by numbers separated by unity.