Abstract: A driving circuit that drives a Hall element for use in a brushless DC motor includes a reference-voltage generator that generates a reference voltage, an operational amplifier to which the reference voltage is input, and a resistance. One of input terminals and GND terminals of all of one or more Hall elements included in the driving circuit are connected to an output end of the operational amplifier. Predetermined potential is applied to the other of the input terminals and the GND terminals of all of the one or more Hall elements. The one or more Hall elements and the resistance are connected in series between a first power supply voltage and ground potential.

Abstract: A motor drive control device that drives and controls a motor by using a PWM inverter includes a dead time compensation portion that obtains a compensation amount to compensate for an error of an output voltage of the PWM inverter generated when a dead time to avoid simultaneous turning-on of respective switching elements mutually connected in series in the PWM inverter is prepared and outputs a voltage command obtained by taking the compensation amount into account to the PWM inverter. The dead time compensation portion obtains the compensation amount based on a magnitude of a current command vector indicating a vector of a current to be followed by a current flowing through the motor. The current command vector is a vector defined by a coordinate system in synchronism with a rotor of the motor or its equivalent coordinate system.

Abstract: A driving circuit that drives a Hall element for use in a brushless DC motor includes a reference-voltage generator that generates a reference voltage, an operational amplifier to which the reference voltage is input, and a resistance. One of input terminals and GND terminals of all of one or more Hall elements included in the driving circuit are connected to an output end of the operational amplifier. Predetermined potential is applied to the other of the input terminals and the GND terminals of all of the one or more Hall elements. The one or more Hall elements and the resistance are connected in series between a first power supply voltage and ground potential.

Abstract: A motor drive control device that drives and controls a motor by using a PWM inverter includes a dead time compensation portion that obtains a compensation amount to compensate for an error of an output voltage of the PWM inverter generated when a dead time to avoid simultaneous turning-on of respective switching elements mutually connected in series in the PWM inverter is prepared and outputs a voltage command obtained by taking the compensation amount into account to the PWM inverter. The dead time compensation portion obtains the compensation amount based on a magnitude of a current command vector indicating a vector of a current to be followed by a current flowing through the motor. The current command vector is a vector defined by a coordinate system in synchronism with a rotor of the motor or its equivalent coordinate system.

Abstract: A mirror rotating apparatus includes a stationary portion and a rotating portion. The stationary portion includes a detection sensor configured to detect rotation of the rotating portion. The rotating portion includes a mirror portion whose outside surface includes a plurality of mirror surfaces that face radially outward. The mirror portion includes a rotation detection surface opposite to the detection sensor, and a balance correction portion defined by a groove or a projection extending in a circumferential direction in the rotation detection surface. The balance correction portion locates a center of gravity of the mirror portion closer to the rotation axis. The rotation of the rotating portion causes the balance correction portion to pass through a region to which light is emitted from the detection sensor.

Abstract: A mirror rotating apparatus includes a stationary portion and a rotating portion. The stationary portion includes a detection sensor configured to detect rotation of the rotating portion. The rotating portion includes a mirror portion whose outside surface includes a plurality of mirror surfaces that face radially outward. The mirror portion includes a rotation detection surface opposite to the detection sensor, and a balance correction portion defined by a groove or a projection extending in a circumferential direction in the rotation detection surface. The balance correction portion locates a center of gravity of the mirror portion closer to the rotation axis. The rotation of the rotating portion causes the balance correction portion to pass through a region to which light is emitted from the detection sensor.