Provided is a motor drive circuit capable of driving a stepper motor even if the load on the stepper motor varies. A motor drive circuit has a first drive circuit that outputs a first drive signal to the driver; a second drive circuit that outputs a second drive signal to the driver; a controller that controls the first drive circuit and second drive circuit. The first drive circuit is configured to output a first drive signal based on the current value of current flow of a coil of a stepper motor. The second drive circuit is configured to output multiple types of second drive signals that differ by the supply time of drive current supplied to the coil. Based on a result of driving by the first drive circuit, the controller selects the type of second drive signal the second drive circuit outputs.

Provided is a motor drive circuit capable of driving a stepper motor even if the load on the stepper motor varies. A motor drive circuit has a first drive circuit that outputs a first drive signal to the driver; a second drive circuit that outputs a second drive signal to the driver; a controller that controls the first drive circuit and second drive circuit. The first drive circuit is configured to output a first drive signal based on the current value of current flow of a coil of a stepper motor. The second drive circuit is configured to output multiple types of second drive signals that differ by the supply time of drive current supplied to the coil. Based on a result of driving by the first drive circuit, the controller selects the type of second drive signal the second drive circuit outputs.

A stepping motor control device is configured to drive a stepping motor by applying a normal drive pulse or a fixed pulse having an energy larger than that of the normal drive pulse. The stepping motor control device includes a determination unit configured to, based on whether or not a pulse applied to the stepping motor before the normal drive pulse is the fixed pulse, determine whether or not to add a degaussing pulse is applied to the normal drive pulse, the degaussing pulse being a pulse for canceling a residual magnetic flux generated in a stator of the stepping motor when the fixed pulse; and a drive control unit configured to, based on a determination result of the determination unit, drive the stepping motor with the normal drive pulse to which the degaussing pulse is added.

A motor and a method of operating the motor uses an encoder disk attached to the rotor of the motor and an encoder reader positioned to optically obtain rotational information of the rotor. The encoder disk and the encoder reader are located within an interior region of the stator of the motor in which the rotor is positioned to rotate.

A motor and a method of operating the motor uses an encoder disk attached to the rotor of the motor and an encoder reader positioned to optically obtain rotational information of the rotor. The encoder disk and the encoder reader are located within an interior region of the stator of the motor in which the rotor is positioned to rotate.

An electronic watch includes a driver controlled to be in an ON state in which a drive current is supplied to a coil of a watch motor, and an OFF state in which the drive current is not supplied, a current detector that detects a current value flowing through the coil, a driver controller that controls the driver, a polarity switching controller that alternately switches a polarity of the drive current to a first polarity and a second polarity, a sampling controller that, at a sampling cycle, intermittently causes the current detector and the driver controller to operate, and a sampling cycle setting controller that detects a sampling cycle setting condition and changes the sampling cycle in at least two stages of a first cycle and a second cycle longer than the first cycle.

An electronic watch includes a driver controlled to be in an ON state in which a drive current is supplied to a coil of a watch motor, and an OFF state in which the drive current is not supplied, a current detector that detects a current value flowing through the coil, a driver controller that controls the driver, a polarity switching controller that alternately switches a polarity of the drive current to a first polarity and a second polarity, a sampling controller that, at a sampling cycle, intermittently causes the current detector and the driver controller to operate, and a sampling cycle setting controller that detects a sampling cycle setting condition and changes the sampling cycle in at least two stages of a first cycle and a second cycle longer than the first cycle.

A method for controlling a polyphase actuator includes supplying each phase with a periodically varying voltage having a periodic sequence of steps P.sub.i that have a constant duration and an amplitude A.sub.n,i, where n corresponds to the rank of the phase and i to the rank of the step. The method further includes determining a target position PC.sub.i of a rotor of the actuator, in order to define a sinusoidal voltage envelope. The actuator further includes a movable member, a stator equipped with electrical coils and a sensor detecting the mechanical position of the movable member with respect to the stator, as well as a microcontroller. The microcontroller determines, at times T.sub.capteur, a mechanical position of a mechanical member, the microcontroller calculates, at each of the times T.sub.capteur, a difference between the mechanical position and a target position PC.sub.i corresponding to the step P.sub.i and the microcontroller calculates a coefficient k as a function of the difference. The microcontroller also weights the amplitude of a power supply applied to the phases by a coefficient k in order to supply the phases with weighted amplitude voltages A.sub.n,i*k.

A method for controlling a polyphase actuator includes supplying each phase with a periodically varying voltage having a periodic sequence of steps P.sub.i that have a constant duration and an amplitude A.sub.n,i, where n corresponds to the rank of the phase and i to the rank of the step. The method further includes determining a target position PC.sub.i of a rotor of the actuator, in order to define a sinusoidal voltage envelope. The actuator further includes a movable member, a stator equipped with electrical coils and a sensor detecting the mechanical position of the movable member with respect to the stator, as well as a microcontroller. The microcontroller determines, at times T.sub.capteur, a mechanical position of a mechanical member, the microcontroller calculates, at each of the times T.sub.capteur, a difference between the mechanical position and a target position PC.sub.i corresponding to the step P.sub.i and the microcontroller calculates a coefficient k as a function of the difference. The microcontroller also weights the amplitude of a power supply applied to the phases by a coefficient k in order to supply the phases with weighted amplitude voltages A.sub.n,i*k.

An electronic watch includes a motor including a coil, a driver controlled to an ON state for supplying a driving current to the coil and an OFF state for not supplying the driving current, a driver controller configured to control the driver to the ON state or the OFF state depending on a value of a current flowing through the coil, and a polarity switcher configured to switch a polarity of the driving current when a prescribed condition is satisfied after detecting that an ON time, which is a duration of the ON state of the driver controller, reaches a maximum.