Abstract: An electric wiring system has a plurality of terminal units, a plurality of sensors connected to the terminal units by signal input lines, and a central control unit connected to the terminal units by a pair of common power supply lines, which receive signals from the sensors. The central control unit has a reference signal generator circuit which repetitively generates a reference signal composed of a train of pulses, a predetermined number of which are assigned to each of the sensors, a modulator circuit for applying the reference signal to the power supply lines, a demodulator circuit for picking up a composite signal generated by the terminal unit from the power supply line, and a control circuit for detecting abnormal and normal signals of the sensors and breakage of the power supply lines and signal input lines based on the presence and absence of high-frequency pulses in the composite signal, thus indicating sensor and line conditions.

Abstract: An ultrasonic wave conversion apparatus comprises electrodes, a support member for supporting the electrodes, a vibrator secured to the support member by a securing member, and a moving diaphragm fixed to the vibrator by a fixing member. The surface of portions of the electrodes, the vibrator, the moving diaphragm and the fixing member are coated with an insulating film of a predetermined thickness. The coating with this insulating film provides the apparatus with an excellent insulating and anticorrosive property and further an excellent damping characteristic for the vibration of the vibrating members of the apparatus.

Abstract: An ultrasonic wave transmitter and receiver adapted to be mounted on the rear portion of a vehicle to detect the distance between the rear end of the vehicle and any obstruction located at the rear side of the vehicle. The ultrasonic wave transmitter and receiver includes an ultrasonic transducer attached to a lower part of the vehicle at a portion spaced from the rear end of the vehicle in the forward direction of the vehicle by a predetermined distance, a horn opening rearwardly from the vehicle and a wave guide tube through which the horn and the ultrasonic transducer are coupled to each other. The distance between the ultrasonic transducer and the rear end of the vehicle is selected to correspond to a time length which is long enough to sufficiently attenuate the residual oscillation of the ultrasonic transducer.

Abstract: A rotation detection apparatus has a first input side disk plate having first and second circumferentially arranged electrodes. An output side second disk plate has electrodes arranged in a circumferential direction to oppose the first plate. One of the disk plates is stationary and one is rotatable. A circuit is provided for supplying a periodic signal of a predetermined period to the first and second electrodes of the first plate. A rotation signal generating circuit is provided for detecting a phase condition between the signal at the electrodes of the second plate and the signal from the periodic signal supplying circuit and generating a rotation signal. A signal transmission device is also provided for transmitting a signal between the rotating plate and the stationary plate.

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: A rotation detecting apparatus includes a transformer consisting of a primary coil disposed to be energized by an energizing source and two secondary coils connected in opposite polarity to each other on the longitudinal sides of the primary coil. The magnetic coupling of the transformer is changed in response to the rotation of a rotating body and this changes the phase of the composite voltage signal of the secondary coils. By virtue of this construction, not only the rotation of the rotating body can be detected at low rotational speeds, but also the rotation can be detected accurately without being affected by the ambient temperature.

Abstract: A rear obstacle detecting system for automotive vehicles includes an ultrasonic transmitter/receiver unit, distance detecting unit and an indicator for measuring distance to an obstacle while a vehicle is in backward movement. The ultrasonic transmitter/receiver unit having a ultrasonic vibrator is always energized as long as the vehicle is in an operating condition irrespective of whether the vehicle is in a backward movement or not, in order to maintain the ultrasonic vibrator being vibrated to achieve a self-cleaning function. The indicator is energized only when the vehicle is in backward movement.

Abstract: A capacitor type displacement or load sensor includes a first electrode constituted by an electrically conductive coiled spring capable of expansion and contraction and a second electrode positioned to face the first electrode without making contact therewith. The second electrode is constituted by an electrically conductive coiled spring or a cylindrical electric conductor. The sensor is constructed such that capacitance between the first and second electrodes varies with a change of a gap between the first and second electrodes or an opposing area of the first and second electrodes caused by the relative displacement occurring therebetween.

Abstract: In an oscillator circuit responsive to a predetermined temperature and including an astable multivibrator, a switching transistor inverts an output voltage from a first transistor of the multivibrator with a predetermined time delay, and a feedback capacitor is responsive to the inverted output voltage from the switching transistor to bias a reference capacitor connected between the output terminal of the first transistor and the input terminal of a second transistor of the multivibrator at opposite voltage polarity relative to that of a terminal voltage across the reference capacitor, a capacitance of the feedback capacitor being determined to turn off the second transistor due to the bias of the feedback capacitor when ambient temperature becomes the predetermined one under exposure of the second transistor to the ambient temperature.

Abstract: A liquid level monitoring device includes a casing arranged to be immersed in liquid stored within a container, the casing having first and second ports and being integrally provided with a support member to be attached to the inner wall of the container. A flexible diaphragm is assembled to form first and second chambers in the casing, the first chamber being communicated with the atmospheric air through the first port from which an elongated tube extends into the exterior of the container, and the second chamber permitting the immerse of liquid through the second port thereinto such that an amount of the atmospheric air is compressed within the second chamber in dependence upon an amount of the stored liquid to flex the diaphragm by a pressure difference between the chambers. A pressure transducer is provided to detect the rate of flexure of the diaphragm so as to generate an electric signal indicative of the liquid surface level from a control circuit.

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: A capacitance sensing device for detecting the amount of material flowing through a passage includes layers of disk-shaped insulating substrates having electrode films formed on surfaces thereof facing each other, and the insulating substrates are supported by an insulating support member as a unit and spaced from each other. The electrode films are alternately connected by a pair of conductors to form a capacitor. Electric circuit elements, forming a detection circuit which is connected to the pair of conductors and which detects a change in capacitance of the capacitor depending on the amount of material flowing through the spaces between the electrode films, are formed on the outer surface of an outermost one of the substrates in a form of a monolithic circuit or a hybrid circuit.

Abstract: A capacitive rotational position detecting apparatus includes a stationary disk plate and a rotatable disk plate in opposite relation. The stationary plate has a first and a second electrode on one surface, each of which is electrically connected through apertures by a metal film formed on the other surface of the stationary plate to reduce a distribution capacitance formed between metal films of the stationary and rotatable plates.

Abstract: An apparatus responsive to the amount of refrigerant flow in a refrigerant circulating system includes a sensing capacitor mounted in a refrigerant passage, the capacitance of the sensing capacitor being varied depending on a change in the dielectric constant of the refrigerant which in turn being dependent on the amount of the refrigerant. The sensing capacitor forms an element of a resistance-capacitance oscillatory circuit and it also forms a ring oscillator together with another capacitor and a plurality of inverters and resistors. The oscillation frequency of the ring oscillator is detected to determine the amount of the refrigerant flowing through the refrigerant passage.

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: Pressure changes in the engine case of an automobile are sensed to compute and display the engine rpm irrespective of the types of engines. A pressure sensing element is mounted on the oil filler port in the engine cylinder head cover by means of a mounting member made of an elastic material.

Abstract: In an oscillator circuit including a variable capacitor for inverting a pair of inverters oppositely to each other with a time period defined by a resistance value of a resistor and a capacitance of the variable capacitor, an additional capacitor is provided to be biased by an inverter function of an additional inverter in voltage polarity opposite to that of the variable capacitor.

Abstract: A temperature measuring apparatus includes a transmitter for continuously transmitting an ultrasonic wave into a propagation medium the temperature of which is to be measured. Two receivers are located along an ultrasonic wave propagation path spaced from each other by a predetermined distance. A phase difference between the ultrasonic waves received by the two receivers is detected as a pulse width which varies depending on a propagation velocity of the wave and hence a temperature of the propagation medium. An obstacle detecting and alarming circuit is provided to detect the presence of an obstacle between the transmitter and the receivers by detecting the absence of the phase difference signal.

Abstract: An ultrasonic wave signal transmitted from an ultrasonic wave transmitter and propagating through an ultrasonic wave propagation medium is received by two ultrasonic wave receivers disposed in a sensor part in a relation spaced apart by a predetermined distance from each other in the direction of transmission of the signal. The sensor part generates a detected phase difference signal having a pulse width corresponding to the phase difference between the ultrasonic wave signal received by one of the two receivers and that received by the other receiver. This detected phase difference signal is applied to a measuring/display part which generates a pulse signal having the number of pulses corresponding to the detected phase difference, and an up/down counter counts the number of pulses of this pulse signal. On the basis of the result of counting by the counter, the temperature of the medium between the transmitter and the receivers is measured and displayed on a display.

Abstract: An ultrasonic temperature measuring apparatus includes a display section and a sensor section connected therebetween with a signal line and a ground line. The display section produces and transmits an excitation signal producing signal having a frequency 1/N times that of an excitation signal for a ultrasonic vibrator over the signal line to the sensor section. In the sensor section, in response to the excitation signal producing signal, the excitation signal is produced to excite the ultrasonic wave vibrator and to transmit the ultrasonic wave continuously into a propagation medium. The ultrasonic wave received at a receiver spaced from the ultrasonic vibrator by a predetermined distance is phase compared with the excitation signal and a pulse difference signal having a pulse width indicative of the phase difference and hence a temperature of the propagation medium is produced.