Abstract: A luggage door unlocking device for a vehicle, by which a luggage door of the vehicle can be unlocked without using an unlocking key, is disclosed. The device comprises a portable transmitter for generating an unlocking signal of ultrasonic wave, an ultrasonic wave receiver which is mounted on the vehicle and which receives an ultrasonic wave from the portable transmitter, a discriminating means for subjecting the signal received by the ultrasonic wave receiver to waveform shaping to obtain a high-frequency pulse train and detecting a high-frequency pulse train of a predetermined pattern to obtain the unlocking signal, and an unlocking mechanism for unlocking the luggage door of the vehicle upon receipt of the unlocking signal after discrimination by the discriminating means. The transmitter has a power supply switch which is enclosed in a case having a clip for attachment to the clothes of the person who carries the transmitter and which is closed upon attachment of the clip to the clothes.

Abstract: An ultrasonic transducer having an ultrasonic vibrator for transmitting and receiving ultrasonic waves, and a reflecting plate for imparting directivity to the ultrasonic waves transmitted by the ultrasonic vibrator and for converging the received ultrasonic waves. In the reflecting plate, at least one through hole is formed for passing snow and mud blown upon the reflecting plate by the wind. Each through hole is configured so as not to deteriorate substantially the reflective capacity of the plate.

Abstract: An ultrasonic detection circuit for detecting obstacles behind a backing motor vehicle, and an ultrasonic communication circuit are automatically switched such that the ultrasonic detection circuit is operable only when the communication circuit is not in use. Furthermore, the ultrasonic detection circuit may be operated only when the motor vehicle is in one or more particular operating conditions. The system comprises a rear ultrasonic transducer used for both the detection circuit and for the communication circuit so that detection of obstacles behind the vehicle and communication with another motor vehicle behind the vehicle are possible, and a front ultrasonic transducer used for only the communication circuit so that communication with another motor vehicle ahead of the vehicle is also possible.

Abstract: A novel visitor conversation system comprising a single transmitter-receiver. The distance to an incoming person is measured by receiving an ultrasonic wave signal propagated from the transmitter-receiver and reflected on the person. When the distance is shorter than a predetermined detection distance, it is decided that the person is a visitor. The transmitter-receiver further propagates an ultrasonic wave amplitude-modulated on an audio signal, and the signal received is demodulated for the purpose of a speech. The visitor detection and the conversation with a vehicle carrying a speaking device are performed by a single medium.

Abstract: A fuel injection timing detecting apparatus for Diesel engines detects the displacement of a preliminarily-magnetized pressure pin which is contained in the body of a fuel injection nozzle of a Diesel engine to be moved by the pressure of pressurized fuel supply against the spring force of a pressure spring engaged with the pressure pin. The apparatus includes a magnetic sensing device externally attached to the body of the fuel injection nozzle for sensing a magnetic variation caused by the movement of the pressure pin thereby to detect the displacement of the pressure pin, and a signal processing circuit for amplifying and processing the output signal of the magnetic sensing device, whereby the apparatus is applicable to conventional fuel injection nozzles of Diesel engines without any need to modify the nozzles and makes it possible to detect easily and accurately fuel injection timings of the fuel injection nozzles.

Abstract: An internal combustion engine rpm detection system, which detects the rpm of an automotive internal combustion engine, comprises a magnetic sensor section for forcibly magnetizing a valve rocker arm in the neighborhood of an oil inlet formed in a cylinder head cover of the internal combustion engine and for detecting the magnetic field changes in the valve rocker arm accompanying the motion thereof. A processing section supplies a drive signal to said magnetic sensor section and converts the output of said magnetic sensor section representing magnetic field changes accompanying the rocking motion of the valve rocker arm into a pulse signal. The magnetic sensor section and processing section are removably mounted as an integral unit in the oil inlet of the engine.

Abstract: An apparatus for detecting displacements of existing movable bodies made of ferromagnetic materials and magnetized by external magnetic fields, comprising a magnetic sensor disposed in the vicinity of the movable body for detecting change in the magnetic field caused by the motion of the body, and a processor for converting the outputs of the magnetic sensor into pulse signals.

Abstract: A distance measuring apparatus installed in an automobile to measure with a high degree of accuracy a distance between a road surface and the axle of vehicle body of the automobile in motion. With this distance measuring apparatus, the distance between the point of its installation on the automobile and the road surface is measured by transmitting wave signals from the point of installation toward the road surface, selecting only the reflected wave signals of a predetermined intensity from the received reflected wave signals from the road surface and then integrating and averaging the data of the distance to the road surface derived from the selected reflected wave signals.