Method of controlling a stepping motor
AssigneeBrother Kogyo Kabushiki Kaisha
InventorKenji Sakakibara
Life of this patent
Estimating the term…
Abstract
A stepping motor having a plurality of phase windings and a rotor which is driven toward a desired position with selective variations of the lead interval between the energized phase windings and the current rotational position of the rotor. Two of the phase windings are alternately selected in a predetermined sequence for strongly accelerating or decelerating the rotor, and only one of the phase windings is energized while the rotor is rotated at a constant speed or is held at any rest position. Thus, the rotor is driven to the desired position in a short time and a substantial amount of power which is supplied to the phase windings for driving the rotor is saved.
Claims12
In a system including a stepping motor having a plurality of phase windings and a rotor which is held in one of a plurality of stable stopping positions provided at intervals of one step, each of said stable stopping positions being defined by one of said phase windings, and means for driving said rotor responsive to the current rotational position of said rotor and the rotational speed of said rotor, a method comprising the steps of
- sequentially energizing two selected phase windings which produce a magnetic field within a first rotational range relating to the current rotational position of said rotor, whereby said rotor is accelerated until it passes through the substantially middle point in the entire distance between a start position and a desired position,
- sequentially energizing two selected phase windings which produce a magnetic field within a second rotational range relating to the current rotational position of said rotor, whereby said rotor is decelerated from a predetermined first position beyond said middle point to a second position where the rotational speed of said rotor drops to a predetermined value,
- sequentially energizing a selected phase winding which produces a magnetic field within a third rotational range relating to the current rotational position of said rotor, whereby the rotational speed of said rotor is kept at substantially said predetermined value until said rotor arrives at a predetermined third position, in several steps, before said desired position,
- selectively energizing two selected phase windings for a period determined by the rotational speed of said rotor in order to brake said rotor approaching said desired position, and
- supplying a final drive signal to only one phase winding corresponding to said desired position in order to stop and hold said rotor at said desired position.
A system comprising
- a stepping motor having a plurality of phase windings and a rotor which is held in one of a plurality of stable stopping positions provided at intervals of one step, each of said stable stopping positions being defined by one of said phase windings,
- first means for detecting the current rotational position of said rotor in order to produce position signals indicating a plurality of predetermined rotational positions of said rotor, and
- second means for coupling said motor and said first means in order to drive said rotor toward a desired position responsive to said position signals,
- said second means sequentially energizing two selected phase windings which produce a magnetic field within a first rotational range relating to the current rotational position of said rotor, whereby said rotor is accelerated until it passes through substantially the middle point in the entire distance between a start position and a desired position,
- said second means sequentially energizing two selected phase windings which produce a magnetic field within a second rotational range relating to the current rotational position of said rotor, whereby said rotor is decelerated from a predetermined first position beyond said middle point to a second position where the rotational speed of said rotor drops a predetermined value,
- said second means sequentially energizing a selected phase winding which produces a magnetic field within a third rotational range relating to the current rotational position of said rotor, whereby the rotational speed of said rotor is kept at substantially said dropped value until said rotor arrives at a predetermined third position in several steps before said desired position,
- said second means selectively energizing two selected phase winding for a period determined by the rotational speed of said rotor in order to brake said rotor approaching said desired position,
- said second means supplying a final drive signal to only one phase winding corresponding to said desired position in order to stop and hold said rotor at said desired position.
Dependencies are inferred from the claim text.