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As the car-mount electronic control devices are increasing in number and variety, power train control devices for controlling actuators such as motors and solenoids are intensively developed at great speed. The electronic circuits used in these devices contain microcomputers, LSIs and ICs that have arithmetic processing functions, and power transistors that drive the actuators, and therefore they are always accompanied by the problem of temperature rise of electronic circuit elements due to heat generation of power transistors caused by operation of the devices, which made it difficult to reduce the size of the device while guaranteeing the reliability.

The purpose of this paper is to outline some of the approaches to provide an exhaust gas high temperature sensor with wide temperature detection range and fast responsiveness. Conventional exhaust gas temperature sensors were designed only to detect an overheating catalyst, so they were unable of detecting temperatures below 600°C. Their slow responsiveness prevented them from detecting rapid catalyst temperature changes. The development of a new thermistor material enabled the sensor to measure a wide temperature range of 300°C to 1000°C. This new sensor provides fast response time (x = 8.7seconds.) as well as durability capability to 1000°C Applications for this sensor include in catalyst preheating and OBD-II systems.

Recently there is demand for rotation sensors capable of high-accuracy detection and very low-speed detection of rotation at high temperature for automobile use. To meet this requirement, a rotation sensor using an InSb thin-film magneto-resistors with good thermal stability has been developed. This sensor transduces magnetic flux change due to gear rotation to resistance change. It is composed of InSb thin-film magneto-resistors fabricated by a newly developed process and signal shaping circuits where resistor signals are converted to digital signals using no amplifier. Accordingly, the signals are independent of the measured frequencies, making possible very low speed (0 to 20 Hz) detection. The sensor stably operates in the temperature range from -40 to 150 degree C for thousands hours. There is no need for a shielded harness due to the digital output signal.

A new compact angular rate sensor using quartz crystal was developed for automotive braking systems or vehicle navigation systems. The sensor's operation is based upon Coriolis force imposed on a vibrating bimorph quartz tuning fork. The reasons we used quartz crystal for the tuning fork are summarized below: Quartz crystal's piezoelectric characteristics are beneficial for both inducing vibration in the driving tine elements and detecting Coriolis forces on the sense tine element. Quartz has stable resonant characteristics due to its high Q value (low energy loss). The control circuit has a one-chip C-MOS ASIC which consists of both a digital memory and an analog circuit. Adjustments of gain, zero and temperature offset are achieved using digital calibration.