Mitsuba Corporation

Tomoyuki Ogawa

Yuichi Yanagita

Katsuhiro Tanino

Iwao Tsurubuchi

Takayuki Kawakura

Naohiko Shiga

Mikihito Shimoyama

Various component parts of a driver circuit for drive sources such as electric motors and clutches, such as relays and FETs as well as the drive sources can be tested by selectively energizing the relays and evaluating the voltage levels of the selected points by using the first and second test voltage detection circuits. This testing process is typically executed before the power up of the drive circuit. The test current is so small that the drive sources would not be inadvertently activated and various components would not be damaged even when there is any faulty component in the driver circuit. When any faulty component is detected in the testing process, the driver circuit may be prevented from being powered up so that any undesired operation of the drive sources or permanent damage to various components owing to such a faulty component may be avoided.

Fault detection circuit for a driver circuit

In a control circuit for a vehicle windshield wiper system, a relay energization retaining circuit forms a self-sustaining circuit jointly with a relay drive transistor for driving a wiper relay, and maintains supply of electric current to the wiper motor when the ON signal for the relay drive transistor is terminated as long as the auto stop switch is at the brake position until the auto stop switch subsequently moves on to the drive position. Therefore, when the signal which normally turns on the relay drive transistor is terminated during the time the auto stop switch is at the brake position, because the relay energization retaining circuit keeps the wiper motor running until the auto stop switch changes over from the brake position to the drive position, and the auto stop switch then takes over the task of keeping the wiper motor running until the auto stop switch changes over from the drive position to the brake position, the termination of electric current to the wiper motor always occurs at the time when the auto stop switch changes over from the drive position to the brake position so that the distance or the angular range of the overrunning of the wiper motor is fixed without regard to the timing of terminating the ON signal. Thus, according to the present invention, the rest position of the wiper blade is fixed under all operating conditions.

Control circuit for a windshield wiper system

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Kiryu, Japan

Tomoyuki Ogawa