A motor control circuit includes a driver having ON and OFF states, and outputs a drive signal to a coil of a motor, a lower limit detector detecting whether current flowing through the coil is less than a lower limit, an upper limit detector detecting whether current flowing through the coil is more than an upper limit, a drive controller placing the driver into the ON state based on a detection result in the lower limit detector after the driver is brought into the OFF state, and placing the driver into the OFF state when the upper limit detector detects that the current is more than the upper limit after a predetermined time elapses from the driver being placed in the ON state, and a polarity switcher switching a polarity of the drive signal when an OFF time of the driver satisfies a polarity switching condition.

A stepping motor control device includes a motor drive portion, a rotor position detection portion, and a control portion. The motor drive portion is configured to sequentially switch an excitation pattern of excitation phases of a stepping motor each time a drive pulse signal is supplied thereto. The rotor position detection portion is configured to be capable of detecting a rotor position in a state where a rotor of the stepping motor has stopped. The control portion is configured to supply the drive pulse signal having a number of pulses determined in accordance with the rotor position detected by the rotor position detection portion, to the motor drive portion in a state where a current supplied to the excitation phases has been controlled to a predetermined current value at which the rotor does not rotate.

A stepping motor control device includes a motor drive portion, a rotor position detection portion, and a control portion. The motor drive portion is configured to sequentially switch an excitation pattern of excitation phases of a stepping motor each time a drive pulse signal is supplied thereto. The rotor position detection portion is configured to be capable of detecting a rotor position in a state where a rotor of the stepping motor has stopped. The control portion is configured to supply the drive pulse signal having a number of pulses determined in accordance with the rotor position detected by the rotor position detection portion, to the motor drive portion in a state where a current supplied to the excitation phases has been controlled to a predetermined current value at which the rotor does not rotate.

A motor driving device includes a control unit which outputs a pre-driving signal to control a motor based on command information of an input target number of rotations and detection information of a number of rotations of the motor, and a motor driving unit which drives the motor based on the pre-driving signal. The control unit includes a speed control circuit which outputs speed command information based on the command information of the target number of rotations and the detection information, a stop control circuit which when an input of the command information of the target number of rotations is stopped, outputs stop command information after a predetermined time elapses from detection of stop of the motor, and a driving signal generation circuit which generates a control signal based on the stop command information and the speed command information.

A motor control unit controls a driving current that flows through a coil of a motor to be driven, by controlling a PWM signal supplied to an H bridge circuit constituted by FETs. A current value generation unit detects a driving current based on a voltage that occurs across a current detection resistor, and corrects a detection value by using a first or second correction value. The current value generation unit, if the driving current is detected in the H period of the PWM signal, corrects the detection value by using the first correction value, and if the driving current is detected in the L period of the PWM signal, corrects the detection value by using the second correction value that has a polarity different from a polarity of the first correction value.

The present invention relates to a driving circuit and a driving method for a stepping motor, and an electronic machine using the same. A current value setting circuit generates a current setting value. A constant current chopper circuit generates a pulse modulation signal, which pulse-width modulates by having a detection value of a coil current flowing through a coil approach close to the current setting value. A logic circuit controls a bridge circuit connected to the coil of the stepping motor according to the pulse modulation signal. The current value setting circuit sets the current setting value to a predetermined full-torque setting value in a first period after rotation starts, reduces the current setting value to a predetermined second setting value less than the first setting value in the following second period, and switches to a high-efficiency mode and adjusts the current setting value by means of feedback control.

A motor controller that includes a processing device and a drive circuit. The drive circuit may include a plurality of switches, a motor winding, and a current sensor coupled together in an H-bridge configuration. The processing device is configured to cause a drive current to drive through the motor winding for a minimum amount of time. The processing device is also configured to compare the current through the current sensor to a threshold value at the minimum amount of time. The processing device is also configured to, based on the current being at or above the threshold value at the minimum amount of time, stop the drive current for an off period of time and cause a first decay of the current for a first percentage of the off period of time and a first slow decay for a second percentage of the off period of time.

Systems and techniques detecting a reverse current are disclosed. An apparatus comprises a switching circuit coupled to a load and a reference node. The switching circuit may be capable of conducting a reverse current from the reference node to the load when a voltage at the load is lower than a voltage at the reference node. A voltage source has a first terminal coupled to the load, a second terminal configured to follow a voltage at the load, and produces a voltage proportional to a voltage drop across the switching circuit. A comparator circuit is coupled to compare a voltage at the second terminal of the voltage source to the voltage at the reference node and configured to indicate when the reverse current has a magnitude greater than a predetermined threshold.

Systems and techniques detecting a reverse current are disclosed. An apparatus comprises a switching circuit coupled to a load and a reference node. The switching circuit may be capable of conducting a reverse current from the reference node to the load when a voltage at the load is lower than a voltage at the reference node. A voltage source has a first terminal coupled to the load, a second terminal configured to follow a voltage at the load, and produces a voltage proportional to a voltage drop across the switching circuit. A comparator circuit is coupled to compare a voltage at the second terminal of the voltage source to the voltage at the reference node and configured to indicate when the reverse current has a magnitude greater than a predetermined threshold.

An electronic timepiece enables driving by appropriate drive conditions even when the load on a motor changes. The electronic timepiece includes a motor having a coil; a driver that is controlled to an on state supplying drive current to the coil, and an off state not supplying the drive current; a driver controller configured to control the driver to the on state or the off state based on a control parameter and current value through the coil; and a control parameter setter configured to maintain or change the control parameter based on the on state or the off state control state of the driver controller.