An object of the present invention is to prevent unnecessary driving stop of a stepping motor. A robot arm section includes a robot arm, a stepping motor 31a, a motor driver 31b, an encoder 31c and a step-out detection section 31e. The robot arm has a joint J1. The stepping motor generates power for operating the joint. The motor driver drives the stepping motor according to a target angle. The encoder outputs an encoder pulse every time a drive shaft of the stepping motor rotates by a predetermined angle. The step-out detection section detects a step-out of the stepping motor based on the target angle and a current angle of the stepping motor that is identified based on the encoder pulse. When the stepping motor does not recover from the step-out before a predetermined grace time elapses from a time at which the step-out is detected, the motor driver stops driving the stepping motor at the time point at which the grace time elapses.

A motor driving circuit includes a stepping motor driving circuit that controls driving of a stepping motor, a DC motor driving circuit that controls driving of a DC motor, and a control circuit that controls the stepping motor driving circuit and the DC motor driving circuit. The control circuit, upon accepting a driving instruction for driving the stepping motor in the middle of the DC motor driving circuit performing driving of the DC motor, stops driving of the DC motor by the DC motor driving circuit, and starts driving of the stepping motor by the stepping motor driving circuit.

A motor driving circuit includes a stepping motor driving circuit that controls driving of a stepping motor, a DC motor driving circuit that controls driving of a DC motor, and a control circuit that controls the stepping motor driving circuit and the DC motor driving circuit. The control circuit, upon accepting a driving instruction for driving the stepping motor in the middle of the DC motor driving circuit performing driving of the DC motor, stops driving of the DC motor by the DC motor driving circuit, and starts driving of the stepping motor by the stepping motor driving circuit.

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 pulse generation unit is configured to output pulse signals for driving the stepping motor. A control unit is configured to perform acceleration control or deceleration control of the stepping motor via the pulse generation unit. The control unit is configured to calculate a number of the pulse signals to be output from the pulse generation unit to the stepping motor when accelerating or decelerating the stepping motor at constant acceleration in the acceleration control or the deceleration control based on an initial speed of the stepping motor when the acceleration control or the deceleration control starts, a target rotation speed, and time from start control of the stepping motor to time when the stepping motor reaches the target rotation speed, and change a rotation speed of the stepping motor in the acceleration control or the deceleration control along a sinusoidal waveform.

A pulse generation unit is configured to output pulse signals for driving the stepping motor. A control unit is configured to perform acceleration control or deceleration control of the stepping motor via the pulse generation unit. The control unit is configured to calculate a number of the pulse signals to be output from the pulse generation unit to the stepping motor when accelerating or decelerating the stepping motor at constant acceleration in the acceleration control or the deceleration control based on an initial speed of the stepping motor when the acceleration control or the deceleration control starts, a target rotation speed, and time from start control of the stepping motor to time when the stepping motor reaches the target rotation speed, and change a rotation speed of the stepping motor in the acceleration control or the deceleration control along a sinusoidal waveform.

A first differential amplifier output drives a first winding of a stepper motor and a second differential amplifier output drives a second winding of the stepper motor. Inputs of the first and second differential amplifiers receive input drive signals generated by either a digital to analog converter or a pulse width modulator, where the input drive signals are phase offset sinusoids. Current flowing through a stepper motor winding is sensed to generate a current sense signal. A stall sensing circuit processes the current sense signal to determine whether the stepper motor has stalled by: taking a first derivative of the current sense signal to generate a first derivative signal; taking a second derivative of the current sense signal to generate a second derivative signal; and processing one or more of the current sense signal, the first derivative signal and the second derivative signal to detect a stepper motor stall condition.

A motor operated valve apparatus includes: a motor driven valve; a drive unit configured to drive the motor; a control unit configured to control the drive unit; and a communication unit configured to communicate with an external controller. The control unit starts control of the motor operated valve according to a command from the external controller; drives the motor in a valve closing direction at start of the control, detects a load on the motor based on a drive pulse output by the drive unit for driving the motor, and sets a driven state when the detected load reaches a predetermined reference value to be a valve switching point of a valve section; and drives the motor relative to the valve switching point of the valve section to perform control so that an opening degree of the valve section becomes a value corresponding to a control command value.

A motor operated valve apparatus includes: a motor driven valve; a drive unit configured to drive the motor; a control unit configured to control the drive unit; and a communication unit configured to communicate with an external controller. The control unit starts control of the motor operated valve according to a command from the external controller; drives the motor in a valve closing direction at start of the control, detects a load on the motor based on a drive pulse output by the drive unit for driving the motor, and sets a driven state when the detected load reaches a predetermined reference value to be a valve switching point of a valve section; and drives the motor relative to the valve switching point of the valve section to perform control so that an opening degree of the valve section becomes a value corresponding to a control command value.