Abstract: An ultrasonic sensor is located in the bottom of a lift cylinder of a forklift and emits ultrasonic waves toward a piston in the cylinder. A controller controls the ultrasonic sensor to consecutively emit ultrasonic waves that have different amplitudes at predetermined intervals. The ultrasonic waves are emitted in order of smallness of amplitude. The controller computes the distance between the ultrasonic sensor and the piston based on a period from when the ultrasonic sensor emits one of the ultrasonic waves to when the ultrasonic sensor receives the ultrasonic wave that is reflected by the piston. As a result, the range of the detectable distances is extended.

Abstract: In a position detecting device which detects a piston rod based on the time elapsed from a point at which an ultrasonic wave is emitted from an ultrasonic wave sensor toward a lower end surface of the piston rod reciprocatingly moved linearly by supply and discharge of a working oil with respect to a hydraulic cylinder to a point at which the ultrasonic wave reflected by the lower end surface of the piston rod is received by the ultrasonic wave sensor, if the working oil's temperature is detected by a temperature sensor, then a microcomputer sets the strength of the ultrasonic wave emitted from the ultrasonic wave sensor in accordance with the temperature of the working oil so as to accurately detect the position of the piston.

Abstract: A fixing member is inserted under pressure into a central hole of an ultrasonic vibrator, a case and a center axle are fixed by a screw, a bearing is fixed on an end portion of the center axle, a rotor is mounted to rotate by the bearing, a connection member is fixed to the rotor, projections are formed on the edge of a disk of the connection member, spaces are formed between the projections respectively, a contact member is composed by inserting ends of divided parts into spaces of the connection member, and a ring-like elastic member is mounted on the contact member which is pressed on the ultrasonic vibrator.

Abstract: An ultrasonic sensor is located in the bottom of a lift cylinder of a forklift and emits ultrasonic waves toward a piston in the cylinder. A controller controls the ultrasonic sensor to consecutively emit ultrasonic waves that have different amplitudes at predetermined intervals. The ultrasonic waves are emitted in order of smallness of amplitude. The controller computes the distance between the ultrasonic sensor and the piston based on a period from when the ultrasonic sensor emits one of the ultrasonic waves to when the ultrasonic sensor receives the ultrasonic wave that is reflected by the piston. As a result, the range of the detectable distances is extended.

Abstract: A scanning circuit consisting of a plurality of time delay circuits and a plurality of holding circuits at least equal in number to the delay circuits is provided for a fish detecting sonar. In response to the input pulse applied to the input terminal of the first stage delay circuit in synchronism with the sound pulse propagated, the delay circuits are triggered to reproduce the input pulses which are sequentially delayed by a time interval equal to the pulse width of the input pulse, and the output pulses from the delay circuits are held only by the holding circuits to which are applied the recording or echo signals. The output pulses held by the holding circuits are picked up by a brush, which slides over the contacts connected to the output terminals, respectively, of the holding circuits, and applied to a recording pen or stylus for recording. The above arrangement permits the recording or display even when the speed of the brush is relatively slow.