Stepping motor exciter apparatus and method

Claim 2

Electrical transducer apparatus comprising: an electrical stepping motor of the type having a rotor member which is magnetically positionable in a plurality of detent positions each located generally intermediate two adjacent pole aligned detent positions by simultaneous excitation of two electrical windings, each winding being associated with one pole of said adjacent pole-aligned detent positions; modulated electrical exciting means connected differentially with said two electrical windings for supplying to said windings differentially divided exciting currents having at least an undulating variation imposed thereon; and commutating means connected with each electrical winding of said stepping motor and with said electrical exciting means for diverting said differentially divided exciting current to subsequent pairs of electrical windings; whereby the electrical inductance of each winding of said two differentially connected windings is dependent upon the degree of alignment between rotor and stator poles instantaneously associated with said winding and current division between said differentially connected windings is responsive to said electrical inductance and to said degree of alignment for producing high current flow in a winding associated with a poorly aligned rotor-stator pole pair and low current flow in a winding associated with a well aligned rotor-stator pole pair.

Claim 3

Electrical transducer apparatus as in claim 1 wherein said stepping motor has a greater number of stator poles than rotor poles.

Claim 4

Electrical transducer apparatus as in claim 1 wherein said stepping motor has eight stator poles and six rotor poles.

Claim 5

Electrical transducer apparatus as in claim 1 wherein said electrical windings and said commutating means are connected to generate magnetic poles of alternating magnetic polarity around the periphery of said sTator member.

Claim 6

Electrical transducer apparatus as in claim 1 wherein said electrical windings are polarized to generate in one semicircular half of said stator member magnetic poles of one polarity and in the remaining semicircular half of said stator member magnetic poles of the opposite polarity.

Claim 7

Electrical transducer apparatus as in claim 1 wherein said stepping motor includes a rotor member having material composition and cross sectional shape capable of transmitting significant quantities of magnetic flux from rotor poles located on one side thereof to rotor poles located on the other side thereof and wherein said electrical windings are connected to direct a significant portion of the magnetic flux generated thereby across at least part of said rotor member during at least part of the operating cycle of said apparatus.

Claim 8

Transducer apparatus for converting electrical energy into precise increments of rotational mechanical energy, said apparatus comprising: an electrical stepping motor member having a multiple poled stator portion and a multiple poled rotor portion, the rotor portion being magnetically rotatable into a plurality of rotor-stator pole aligned first detent positions by excitation of electrical windings associated with a singular rotor step position and magnetically rotatable into a plurality of rotor-stator pole misaligned second detent positions located generally intermediate said first detent positions by concurrent excitation of electrical windings associated with at least two of said first detent step positions; electrical exciter means selectively connected with concurrently excitable electrical windings of said stepping motor non-alignable rotor-stator pole pairs and including a source of electrical energy and a chopper modulated current regulator responsive to the total current flow in both windings of said concurrently excitable non-alignable rotor-stator pole pairs, for supplying to said stepping motor bursts of chopped electrical energy capable of moving said rotor member into successive rotational positions; whereby a dynamic rotor position responsive division of said chopper modulated total current flow occurs between said concurrently excited windings wherein the larger inductance of a closely aligned rotor-stator pole pair produces a smaller winding current flow therein and the smaller inductance of a non-aligned rotor-stator pole pair produces a larger winding current flow therein; and whereby the tendency of said stepping motor rotor member to pass by one of said rotor-stator pole misaligned second detent positions in an overshoot motion is opposed by a decrease of current and magnetic flux in the stator pole ahead of said second detent position and an increase of current and magnetic flux in the stator pole behind said second detent position as said rotor member rotates through said second detent position.

Claim 9

Transducer apparatus for converting electrical energy into precise increments of rotational mechanical energy, said apparatus comprising: an electrical stepping motor member having a multiple poled stator portion and a multiple poled rotor portion, the rotor portion being magnetically rotatable into a plurality of rotor-stator pole aligned first detent positions by excitation of electrical windings associated with a singular rotor step position and magnetically rotatable into a plurality of rotor-stator pole misaligned second detent positions located generally intermediate said first detent positions by concurrent excitation of electrical windings associated with at least two of said first detent step positions; electrical exciter means selectively connected with concurrently excitable electrical windings of said stepping motor non-alignable rotor-stator pole pairs and including a source of electrical energy and a chopper modulated current regulator responsive to the total current flow in both windings of said concurrently excitable non-alignable rotor-stator pole pairs, for supplying to said stepping motor bursts of chopped electrical energy capable of moving said rotor member into successive rotational positions; whereby a dynamic rotor position responsive division of said chopper modulated total current flow occurs between said concurrently excited windings wherein the larger inductance of a closely aligned rotor-stator pole pair produces a smaller winding current flow therein and the smaller inductance of a non-aligned rotor-stator pole pair produces a larger winding current flow therein; and whereby the tendency of said stepping motor rotor member to pass by one of said rotor-stator pole misaligned second detent positions in an overshoot motion is opposed by a decrease of current and magnetic flux in the stator pole ahead of said second detent position and an increase of current and magnetic flux in the stator pole behind said second detent position as said rotor member rotates through said second detent position.

Claim 10

Transducer apparatus as in claim 7 wherein said chopper modulated current regulator in said electrical exciter means includes a current sensing element, an amplifier element and a current switching element connected into a feed-back loop configuration wherein signals from said current sensing element pass through said amplifier element and control the current conducting time in said current switching element and wherein said current switching element is connected between said source of electrical energy and said concurrently excitable electrical windings for controlling current flow therebetween.

Claim 11

Transducer apparatus as in claim 7 wherein said chopper modulated current regulator includes clock means for periodically initiating pulses of current in said stepping motor windings at a rate independent of the electrical time constant of said windings.

Claim 12

Transducer apparatus as in claim 9 wherein said clock means includes electrical timing means for initiating pulses of current at a frequency above the audio frequency range; whereby sound energy emitted by said stepping motor is composed primarily of frequencies above the human audible range.

Claim 13

Apparatus for differentially exciting two electrical windings of a multiple-poled stepping motor, said apparatus comprising: a source of direct current electrical energy; a current sensing element capable of developing a current signal representative of the instantaneous current flow therein; an electrical switching element; said source of direct current electrical energy, said electrical switching element, said current sensing element and a parallel combination of said two electrical windings being connected together in an exciting current series electrical circuit; and pulsed electrical driver means having an input node connected with said current sensing element and an output port connected with said electrical switching element in closed feedback loop fashion for driving said electrical switching element in a pulsed current modulating mode wherein the ratio of conducting and non-conducting time is responsive to said current signal and thereby to the average current flowing in said exciting current series electrical circuit; whereby current regulating action of said closed feedback loop maintains a constant total current flow in said two electrical windings and said constant total current flow can be instantaneously divided between said two electrical windings according to the degree of engagement between stepping motor rotor and stator poles associated with said winding circuits.

Claim 14

Apparatus for differentially exciting two electrical windings of a multiple-poled stepping motor, said apparatus comprising: a source of direct current electrical energy; a current sensing element capable of developing a current signal representative of the instantaneous current flow therein; an electrical switching element; said source of direct current electrical energy, said electrical switching element, said current sensing element and a parallel combination of said two electrical windings being connected together in an exciting current series electrical circuit; and pulsed electrical driver means having an input node connected with said current sensing element and an output port connected with said electrical switching element in closed feedback loop fashion for driving said electrical switching element in a pulsed current modulating mode wherein the ratio of conducting and non-conducting time is responsive to said current signal and thereby to the average current flowing in said exciting current series electrical circuit; whereby current regulating action of said closed feedback loop maintains a constant total current flow in said two electrical windings and said constant total current flow can be instantaneously divided between said two electrical windings according to the degree of engagement between stepping motor rotor and stator poles associated with said winding circuits.

Claim 15

Apparatus for differentially exciting as in claim 11 wherein said pulsed electrical driver means includes an input node and a source of bias signals connected thereto for altering the ratio of conducting and non-conducting times in said electrical switching element; whereby bias signals for altering the magnitude of current flowing in said exciting current series electrical circuit may be applied to said apparatus.

Claim 16

Apparatus for differentially exciting as in claim 11 wherein said pulsed electrical driver means includes clock timing means for periodically initiating conductivity in said electrical switching element; whereby the pulsing rate of said pulsed electrical driver means may be positively established at a predetermined frequency.

Claim 17

Apparatus for differentially exciting as in claim 11 wherein said pulsed electrical driver means includes operational amplifier circuit means connected as a saturating amplifier pulse width modulator for determining time duration of the current modulating pulses in said electrical switching element.

Claim 20

A method for exciting as in claim 15 including the step of: augmenting the magnitude of said following pole exciting current after said rotor has rotated through a position of maximum alignment with said following pole in an over-shoot motion; whereby said rotor is urged backward toward said following pole.

Claim 21

A method for exciting as in claim 15 including the steP of: diminishing the magnitude of said following pole exciting current as said rotor member re-approaches a position of maximum alignment with said following pole during relaxation from an overshoot motion.

Claim 22

A method for exciting as in claim 15 wherein said exciting current is a direct current having superimposed thereon a pulse modulated regulation component and wherein said preceding pole and following pole currents are derived from said pulse modulated direct current; whereby said preceding pole exciting current and said following pole exciting current are instantaneously responsive to the electrical inductance and the magnetic reluctance properties of both said preceding pole and said following pole as the alignment of said preceding and following poles with poles of said rotor member changes during rotor movement.

Claim 23

A method for exciting as in claim 18 wherein said preceding pole and said following pole exciting currents are currents derived differentially from said pulse modulated direct current; whereby the magnitude of said following pole exciting current is responsive to electrical inductance and magnetic reluctance property changes in both said preceding pole and said following pole; and whereby the magnitude of said preceding pole exciting current is responsive to electrical inductance and magnetic reluctance property changes in both said preceding pole and said following pole.