Nippondenso Co., Ltd.

Denso Corporation

Nippon Soken, Inc.

Yasutaka Nakamori

Shigenori Isomura

Tomomichi Mizoguchi

Yasufumi Yamada

Yoshimi Natsume

Yasuyuki Sakakibara

Jun Hasegawa

Toshihiro Suzumura

Kiyomitsu Kozawa

An in-vehicle drive assist system adjusts a viewing angle of a camera mounted in a vehicle using environmental information obtained from outside the vehicle. An early risk determination is thus allowed to be made in the vehicle, while maintaining reliability.

Drive assist system for vehicle

To shorten the time during which oxygen concentration cannot be detected, the temperature of an oxygen concentration sensor is detected by negatively biasing the sensor using a bias control circuit. A microcomputer estimates a saturated current thereof at one time before the current flowing through the sensor section ends rising based on a current detected by a current detecting circuit at that time. Further, the sensor is positively biased right after the elapse of a negative bias voltage application period by the bias control circuit. The microcomputer determines the air-fuel ratio based on the current flowing through the sensor at that time. The period in which the negative bias is applied is variably set appropriately by the microcomputer in response to changes of engine temperature and intake air amount. Furthermore, to activate the sensor quickly, the temperature of the sensor section is detected and a heater is controlled based thereon.

Oxygen concentration detecting apparatus

An oxygen concentration measuring device capable of significantly shortening the period of time during which oxygen concentration cannot be measured. When measuring the temperature of a sensor main body, a microcomputer determines the temperature of the sensor main body by estimating a saturation current starting from a current detected by a current detecting circuit in a period of time before current flowing through the sensor main body finishes rising, after the sensor main body has been negatively biased by a bias control circuit. The sensor main body is positively biased by the bias control circuit directly after the period of time has lapsed. The microcomputer determines an air fuel ratio by using current in a period of time before current flowing through the sensor main body due to the positive bias finishes decreasing.

Oxygen concentration measuring device

Disclosed is a piezoelectric actuator driving apparatus in which a piezoelectric element used to operate as an electro-mechanical transducer is suitably charged and discharged so that the piezoelectric element can make a predetermined amount of mechanical displacement. In the apparatus, the energy of electric charge causing expansion of the piezoelectric element is controlled by a plurality of pulse signals. Each of these pulse signals acts to store electric charge having a predetermined amount of energy in a capacitor, so that the amount of electric charge stored in the capacitor increases with the increase in the number of the pulse signals. After the total amount of the energy of the electric charge stored in the capacitor attains a predetermined value sufficient to cause expansion of the piezoelectric element, the electric charge stored in the capacitor is supplied to the piezoelectric element. Thus, even when a high speed response and high energy are demanded for controlling the amount of expansion of the piezoelectric element, this demand can be readily dealt with. On the other hand, when the electric charge stored in the piezoelectric element is discharged, voltages applied to the piezoelectric element and the primary and secondary windings of a transformer are controlled so as to prevent deterioration of the piezoelectric element.

Piezoelectric actuator driving apparatus

A driving device for a piezoelectric element for electrically driving a piezoelectric element to obtain a predetermined mechanical displacement, the piezoelectric element driving device being provided with a transformer having a primary winding and a secondary winding, the secondary winding being connected to the piezoelectric element; a switching element connected to the primary winding and controlling the amount of energy stored in an air-gap of the core of the transformer; and an energy control means for driving the switching element so that the amount of energy stored in the air-gap of the core of the transformer becomes a set value, the displacement of the piezoelectric element being controlled by the amount of energy stored in the air-gap of the core of the transformer.

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Anjo, Japan

Yasutaka Nakamori