Abstract: A motor controller for controlling a drive of a motor having plural phase windings includes upper and lower arm circuits and a control unit. The control unit switchingly controls ON/OFF of switches of the upper and lower arm circuits, for sequentially switching an energized phase of the motor. Then, from among the plural switches, a switch forming an energization path to the energized phase is designated as an energized phase switch with the others of the plural switches being designated as non-energized phase switches. Further, from among the non-energized phase switches, a switch forming a path of a reflux current that accompanies the switching of the energized phase is designated as a reflux switch. Then, the control unit performs an ON control of the energized phase switch in addition to performing an ON control of the reflux switch.

Abstract: A first arithmetic circuit computes a propagation velocity of an ultrasonic wave based on a first time difference between an output timing, at which an ultrasonic element outputs an ultrasonic wave, and a reference timing, at which a comparator circuit outputs a detection signal on reflection off a distal end of a reference pipe, and a length of the reference pipe. A period circuit sets a propagation path detection period to detect a liquid level timing, at which the comparator circuit outputs the detection signal on reflection off the liquid level, based on a longest and shortest propagation path lengths and the propagation velocity. A second arithmetic circuit computes the length of the propagation path based on a second time difference, which is between the liquid level timing and the output timing during the propagation path detection period, and the propagation velocity.

Abstract: An ultrasonic element generates an ultrasonic wave and converts an input ultrasonic wave into an electric signal. A transmission circuit outputs a drive signal to the ultrasonic element. A comparator circuit outputs a first detection signal when the electric signal becomes larger than a threshold value and outputs a second detection signal when the electric signal becomes smaller than the threshold value. An arithmetic circuit computes a distance of a propagation path of the ultrasonic wave based on a time difference between an output timing, at which the ultrasonic element outputs of the ultrasonic wave, and a liquid level timing, at which the comparator circuit outputs the first detection signal, and based on a propagation speed of the ultrasonic wave. A storage unit stores a time difference between the first detection signal and the second detection signal. The transmission circuit increases the drive signal, as the time difference decreases.

Abstract: An ultrasonic distance measuring device retrieves an ultrasonic wave propagation speed from a correlation between an output of a medium sensor and a corresponding ultrasonic wave propagation speed. The ultrasonic distance measuring device sets a propagation path detection period for detecting a detection signal, which corresponds to the ultrasonic wave reflected by a liquid surface, based on a longest propagation path length and a shortest propagation path length between the liquid surface and the retrieved propagation speed of the ultrasonic wave. The ultrasonic distance measuring device calculates a distance of the propagation path based on a time difference between a detection timing of the detection signal and an output timing of the ultrasonic wave in a propagation path detection period, and the propagation speed of the ultrasonic wave.

Abstract: A liquid level detector has an ultrasonic sensor connected thereto by two signal lines. When a drive signal is output from a drive circuit, the drive signal is output via an impedance matching circuit, thereby transmission and reception signals on the signal lines flow as complementary level signals. A receiver circuit obtains an amplified signal by amplifying the transmission and reception signals with a differential amplifier circuit, and by cutting a same phase noise signal.

Abstract: A motor controller for controlling a drive of a motor having plural phase windings includes upper and lower arm circuits and a control unit. The control unit switchingly controls ON/OFF of switches of the upper and lower arm circuits, for sequentially switching an energized phase of the motor. Then, from among the plural switches, a switch forming an energization path to the energized phase is designated as an energized phase switch with the others of the plural switches being designated as non-energized phase switches. Further, from among the non-energized phase switches, a switch forming a path of a reflux current that accompanies the switching of the energized phase is designated as a reflux switch. Then, the control unit performs an ON control of the energized phase switch in addition to performing an ON control of the reflux switch.

Abstract: An ultrasonic distance measuring device retrieves an ultrasonic wave propagation speed from a correlation between an output of a medium sensor and a corresponding ultrasonic wave propagation speed. The ultrasonic distance measuring device sets a propagation path detection period for detecting a detection signal, which corresponds to the ultrasonic wave reflected by a liquid surface, based on a longest propagation path length and a shortest propagation path length between the liquid surface and the retrieved propagation speed of the ultrasonic wave. The ultrasonic distance measuring device calculates a distance of the propagation path based on a time difference between a detection timing of the detection signal and an output timing of the ultrasonic wave in a propagation path detection period, and the propagation speed of the ultrasonic wave.

Abstract: An ultrasonic element generates an ultrasonic wave and converts an input ultrasonic wave into an electric signal. A transmission circuit outputs a drive signal to the ultrasonic element. A comparator circuit outputs a first detection signal when the electric signal becomes larger than a threshold value and outputs a second detection signal when the electric signal becomes smaller than the threshold value. An arithmetic circuit computes a distance of a propagation path of the ultrasonic wave based on a time difference between an output timing, at which the ultrasonic element outputs of the ultrasonic wave, and a liquid level timing, at which the comparator circuit outputs the first detection signal, and based on a propagation speed of the ultrasonic wave. A storage unit stores a time difference between the first detection signal and the second detection signal. The transmission circuit increases the drive signal, as the time difference decreases.

Abstract: A first arithmetic circuit computes a propagation velocity of an ultrasonic wave based on a first time difference between an output timing, at which an ultrasonic element outputs an ultrasonic wave, and a reference timing, at which a comparator circuit outputs a detection signal on reflection off a distal end of a reference pipe, and a length of the reference pipe. A period circuit sets a propagation path detection period to detect a liquid level timing, at which the comparator circuit outputs the detection signal on reflection off the liquid level, based on a longest and shortest propagation path lengths and the propagation velocity. A second arithmetic circuit computes the length of the propagation path based on a second time difference, which is between the liquid level timing and the output timing during the propagation path detection period, and the propagation velocity.

Abstract: A liquid level detector has an ultrasonic sensor connected thereto by two signal lines. When a drive signal is output from a drive circuit, the drive signal is output via an impedance matching circuit, thereby transmission and reception signals on the signal lines flow as complementary level signals. A receiver circuit obtains an amplified signal by amplifying the transmission and reception signals with a differential amplifier circuit, and by cutting a same phase noise signal.

Abstract: In a motor driving device, a driving switching element is connected in series with a motor between a power source and a ground, and operated by a PWM signal outputted from a control circuit. A return current path forming unit is connected in parallel with the motor to allow a return current when the driving switching element is turned off. A series circuit of a current flow restriction element and a switch is connected in parallel with the return current path forming unit. A disconnection determination unit prohibits output of the PWM signal and closes the switch of the series circuit when a voltage applied to the motor does not fluctuate according to the PWM signal, and determines the disconnection of the motor on condition that the voltage detected in that state indicates a change across a second threshold.

Abstract: In a motor driving device, a driving switching element is connected in series with a motor between a power source and a ground, and operated by a PWM signal outputted from a control circuit. A return current path forming unit is connected in parallel with the motor to allow a return current when the driving switching element is turned off. A series circuit of a current flow restriction element and a switch is connected in parallel with the return current path forming unit. A disconnection determination unit prohibits output of the PWM signal and closes the switch of the series circuit when a voltage applied to the motor does not fluctuate according to the PWM signal, and determines the disconnection of the motor on condition that the voltage detected in that state indicates a change across a second threshold.

Abstract: An electronic unit includes a housing and a plurality of heat-generating electronic devices. The devices are stored in the housing. The heat generated by the devices is transferred to the housing and further transferred to ambient air from the housing to cool the electronic unit. A sheet of paper, which is made of art paper having a thermal emissivity higher than the housing, is adhered to an outer surface of the housing to improve the heat radiation from the housing to the ambient air.

Abstract: An electronic unit includes a housing and a plurality of heat-generating electronic devices. The devices are stored in the housing. The heat generated by the devices is transferred to the housing and further transferred to ambient air from the housing to cool the electronic unit. A sheet of paper, which is made of art paper having a thermal emissivity higher than the housing, is adhered to an outer surface of the housing to improve the heat radiation from the housing to the ambient air.