A movement includes a driver having ON and OFF states, and outputting a drive signal to a coil of a motor, a lower limit detector detecting that a current flowing through the coil is less than a lower limit, a drive controller bringing the driver into the ON state based on a result of the lower limit detector, and bringing the driver into the OFF state based on an elapsed time from the ON state, a polarity switcher switching a polarity of the drive signal when an elapsed time from the OFF state of the driver satisfies a switching condition, and a drive stopper stopping driving of the driver when the OFF time satisfies a stopping condition.

In one implementation, a motor module according to the present invention includes: a motor driving circuit 10 to drive a motor M; and a position estimation device 30 to output an estimated position signal of a rotor R of the motor M. It also includes: a motor control circuit 20 to supply a command voltage value to the motor driving circuit 10 in response to a pulse signal; and a variable step-size memory 40 storing variable step-size information, which defines an amount of displacement of the rotor R per pulse of the pulse signal. The estimated position signal is an analog or digital signal. Upon receiving a pulse signal, the motor control circuit 20 determines the command voltage value based on an estimated position value of the rotor R acquired from the position estimation device 30 and the variable step-size information read from the variable step-size memory 40. The motor driving circuit 10 changes the position of the rotor R based on the command voltage value.

In one implementation, a motor module according to the present invention includes: a motor driving circuit 10 to drive a motor M; and a position estimation device 30 to output an estimated position signal of a rotor R of the motor M. It also includes: a motor control circuit 20 to supply a command voltage value to the motor driving circuit 10 in response to a pulse signal; and a variable step-size memory 40 storing variable step-size information, which defines an amount of displacement of the rotor R per pulse of the pulse signal. The estimated position signal is an analog or digital signal. Upon receiving a pulse signal, the motor control circuit 20 determines the command voltage value based on an estimated position value of the rotor R acquired from the position estimation device 30 and the variable step-size information read from the variable step-size memory 40. The motor driving circuit 10 changes the position of the rotor R based on the command voltage value.

A watch (50) including an electromechanical movement provided with a stepper motor (2) and a control circuit (20) of the motor, and means for contactless communication with an external communication device (100), including an antenna formed by the coil (18) of the motor and arranged to receive an amplitude-modulated magnetic signal according to the encoded data. The communication means are arranged to generate electrical detection pulses supplied to the coil of the motor with a pulse frequency corresponding to an encoding frequency of the magnetic signal.

A watch (50) including an electromechanical movement provided with a stepper motor (2) and a control circuit (20) of the motor, and means for contactless communication with an external communication device (100), including an antenna formed by the coil (18) of the motor and arranged to receive an amplitude-modulated magnetic signal according to the encoded data. The communication means are arranged to generate electrical detection pulses supplied to the coil of the motor with a pulse frequency corresponding to an encoding frequency of the magnetic signal.

A control circuit of a timepiece motor (2), including a bipolar permanent magnet (6), a stator (4) defining two isthmi (12a & 12b) and two rest positions for the rotor, and a coil (18) mounted on the stator. The control circuit can determine the position of the rotor at rest. An electric pulse generator (22) for detecting an external magnetic field formed by a circuits for: measuring the electrical current in the coil after an electrical pulse has been triggered, comparing the measured electrical current with a reference current, measuring the time allowing measuring a rise time between triggering of the electrical pulse and the next time the electrical current flowing in the coil reaches the reference current, and processing the rise time to be able to determine whether the measured rise time indicates the presence of a given external magnetic field passing through the two isthmi.

A control circuit of a timepiece motor (2), including a bipolar permanent magnet (6), a stator (4) defining two isthmi (12a & 12b) and two rest positions for the rotor, and a coil (18) mounted on the stator. The control circuit can determine the position of the rotor at rest. An electric pulse generator (22) for detecting an external magnetic field formed by a circuits for: measuring the electrical current in the coil after an electrical pulse has been triggered, comparing the measured electrical current with a reference current, measuring the time allowing measuring a rise time between triggering of the electrical pulse and the next time the electrical current flowing in the coil reaches the reference current, and processing the rise time to be able to determine whether the measured rise time indicates the presence of a given external magnetic field passing through the two isthmi.

A control unit controls an electric motor based on position data on a window glass, and controls an opening-closing operation of the window glass. The control unit includes a reverse rotation detector which detects a reverse rotation operation of the window glass, a reverse rotation prevention controller which performs reverse rotation prevention processing of the electric motor when a reverse rotation is detected, and a position data correction unit which corrects position data on the window glass in an initial operation after occurrence of a reverse rotation operation. If a pulse signal associated with rotation of the electric motor is not input in an initial operation after the detection of the reverse rotation operation, the position data correction unit determines that the window glass has reached a top dead center position, stops the motor, and corrects the position data with the position data at that time as an origin position.

A control unit controls an electric motor based on position data on a window glass, and controls an opening-closing operation of the window glass. The control unit includes a reverse rotation detector which detects a reverse rotation operation of the window glass, a reverse rotation prevention controller which performs reverse rotation prevention processing of the electric motor when a reverse rotation is detected, and a position data correction unit which corrects position data on the window glass in an initial operation after occurrence of a reverse rotation operation. If a pulse signal associated with rotation of the electric motor is not input in an initial operation after the detection of the reverse rotation operation, the position data correction unit determines that the window glass has reached a top dead center position, stops the motor, and corrects the position data with the position data at that time as an origin position.

Methods of compensating for play and for initializing a position encoder in an actuation system (2) including an actuated system (8) comprising an elastic element, and an actuator (4) with a stepper motor (12) having at least one electrical phase.