Abstract: A loosening detection structure used to detect loosening of a bolt includes a material that is disposed between a fixing subject steel plate and a head portion of a metal bolt for fixing the steel plate and either attached to a seating surface of the head portion of the bolt or attached to a washer disposed between the steel plate and the head portion of the bolt, and that has electrical characteristics that vary in response to variation in a force for fastening the bolt to the steel plate.

Abstract: A transducer includes a conductive sheet installed on a sheath of a cable, an insulative sheet installed on the conductive sheet, holes being formed in predetermined positions of the insulative sheet, and a conductive sheet installed on the insulative sheet, holes being formed in predetermined positions of the conductive sheet. The transducer has structure in which, when the cable is tightened by the screw from the top of the conductive sheet and fixed, the distal end of the screw comes into contact with the conductive sheet passing through the holes formed in the insulative sheet and the conductive sheet, and the conductive sheet and the conductive sheet are electrically connected.

Abstract: Obstacles in the path of a vehicle are detected by an ultrasonic radar system which measures the time between the instance of transmission of an ultrasonic wave pulse and another instance of reception of an echo signal. The transmitting period is controlled to be retarded from a reference or standard transmitting period by a time length including the measured time at every other transmitting period. The measured time is compared with a reference time to check whether a detected obstacle is within a dangerous range. This comparison is effected at every other transmitting period so that a false detection signal caused from a far obstacles is prevented from being produced. As a result of the comparison an alarming device is energized to alert the vehicle driver when necessary.

Abstract: An ultrasonic detector for roadway vehicles comprises an array of electroacoustic transducers mounted on the rear of the vehicle. The transducers are sequentially driven by a transmitter circuit to transmit a pulsed, laterally shifting ultrasonic energy toward an object located behind the vehicle in one of plural regions defined by partially overlapped directivity patterns of adjacent transducers. A receiver circuit is coupled to the transducer array to receive echos returning from the object during the interval between successive beam transmissions. A logic circuit detects the lateral position of and the distance to the object for giving relevant indications on a display unit, the audible tone being variable depending on object distance. An audible warning device is optional.

Abstract: A device for detecting failure of an ultrasonic apparatus having an ultrasonic pulse generator, an ultrasonic transmitter and an ultrasonic receiver utilizes a damped oscillation signal which is produced at the junction point between the ultrasonic pulse generator and the ultrasonic transmitter when the ultrasonic transmitter or the ultrasonic receiver is excited by applying thereto an ultrasonic pulse generated by the ultrasonic pulse generator. A level discriminator compares the damped oscillation signal with a reference level and determines whether the damped oscillation signal has a sufficient magnitude and duration indicating that the ultrasonic transmitter or the ultrasonic receiver is in a normal operating condition.