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 step motor drive device includes a step motor including a rotor, stators, and a coil, a drive circuit that outputs a drive signal including a plurality of partial signals that are output intermittently, a detecting circuit that detects an electromagnetic induced current that is generated in the coil after the partial signals are output, and a control unit that controls the drive circuit. The drive circuit outputs one of the partial signals included in the drive signal to the coil, and, in response to a change in an electromagnetic induced current generated in the coil after the partial signal is output, outputs a next partial signal to the coil. The control unit determines a control method of the step motor based on an interval of the plurality of partial signals, and controls the drive circuit based on the determined control method.

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 watch includes a chargeable power supply, a crystal oscillation circuit including a crystal oscillator and an oscillation circuit and configured to stop oscillating when a power supply voltage falls below an oscillation stop voltage and to start oscillating when the power supply voltage exceeds an oscillation start voltage, which is higher than the oscillation stop voltage, and a divider circuit that outputs a reference signal by dividing an oscillation signal output from the oscillation circuit. The watch also includes a temperature compensation circuit that performs a temperature compensation function operation that compensates for variation of the reference signal due to a temperature, a first voltage detection circuit that detects that the power supply voltage exceeded a first voltage that is set higher than the oscillation start voltage, and a control circuit that starts the temperature compensation function operation of the temperature compensation circuit when the first voltage detection circuit detects that the power supply voltage exceeded the first voltage, and subsequently continues the temperature compensation function operation even when the power supply voltage falls below the first voltage.

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.

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 moter and an OFF state in which the drive current is not supplied to the coil, a target current value setter configured to set a target current value in accordance with a drive voltage for driving the motor, and a driver controller configured to compare a detected current value of a current flowing to the coil with the target current value, control the driver to be in the ON state or the OFF state in accordance with a result of the comparison, and switch polarity of the drive current when detecting that an ON time, which is a duration of the ON state of the driver, meets a predetermined condition or an OFF time, which is a duration of the OFF state of the driver, meets a predetermined condition.

A timepiece includes a motor control unit driving a motor for driving an indicating hand, based on an instruction signal, and a control unit receiving an instruction confirmation signal corresponding to a drive state of the motor in response to the instruction signal from the motor control unit, and determining whether or not the motor is driven in accordance with the instruction signal, based on the instruction confirmation signal.

An oscillating circuit includes an input terminal and an output terminal, to both of which an oscillator is coupled, a DC cut capacitor having one terminal of two terminals that is coupled to the input terminal, an inverter having an input side coupled to the other terminal of the DC cut capacitor and an output side coupled to the output terminal, a first feedback resistor coupled in parallel to the inverter, a second feedback resistor coupled in parallel to the DC cut capacitor and the inverter, and a switch coupled in parallel to the DC cut capacitor.

A motor driving apparatus is a pulse generation circuit applying a drive pulse for rotating a rotor to a two stepping motor including the rotor magnetized in two poles and a stator in which a two-phase coil is wound around a yoke. The drive pulse is constituted of a drive pulse P1 and a drive pulse P2. The pulse generation circuit applies the drive pulse P1 having a stable stationary position at which a rotor rotation angle from a reference position is 90 degrees or less and applies the drive pulse P2 having a stable stationary position at which the rotor rotation angle from the reference position is 90 degrees or more continuously to the application of the drive pulse P1.