Hitachi, Ltd.

Hitachi Automotive Engineering Co., Ltd.

Shigeki Tsuchitani

Seiko Suzuki

Masahiro Matsumoto

Masayuki Miki

Satoshi Shimada

Yoshihiro Yokota

Hiroshi Kuroiwa

Masayoshi Kaneyasu

Seiichi Ugai

Hiromichi Ebine

Kazuji Yamada

Noriyuki Kinjo

Akira Koide

Seikou Suzuki

Norio Ichikawa

Shuichi Ohara

Kazuo Sato

Kazuo Kato

Sadayasu Ueno

Shotaro Naito

Shigeru Oho

Masayoshi Suzuki

Kanemasa Sato

Susumu Murakami

Tomoyuki Tanaka

Masanori Kubota

Shigeyuki Kobori

Toru Sugawara

Yasuhiro Asano

Masahiro Kurita

Yukiko Sugisawa

Tooru Sugawara

Benjamin Kloeck

Yukiko Kawai

A detector for detecting a physical quantity as a quantity of electricity has a detection portion, a portion for stimulating the detection portion and a signal processing portion, wherein a calibration signal is supplied from the signal processing portion to the detection portion via the stimulating portion so as to measure a specific response of the detection portion, whereby self-calibration and correction of the characteristic of the detector are performed in accordance with an amount of a change in the response.

Detector having self-calibration function

A capacitance type accelerometer, having a fist silicon plate formed a movable electrode which is moved according to acceleration, two second silicon plates which are disposed on both sides of the first silicon plate with a certain separation distance, and thermal oxide films which are respectively disposed between the first silicon plate except the movable electrode and the two second silicon plates and stick the first silicon plate except the movable electrode and the two second silicon plates together. And further, a capacitance type accelerometer, having, a silicon plate formed a movable electrode which is moved according to acceleration, glass plates respectively mounting a conductive layer thereon which are opposite to the silicon plate with a certain separation distance and are sticked to the both side of the silicon plate except the movable electrode and leeding wires which are respectively connected to the conductive layers through a groove formed between the silicon plate and the glass plates respectively deriving. These capacitance type accelerometers are made by processing and cutting a wafer by dicing saw without coming into the accelerometer of cutting chips or cutting water.

Capacitance type accelerometer

A semiconductor acceleration sensor is formed by a cantilever having a conductive movable electrode of predetermined mass at one end, at least one pair of fixed conductive electrodes which are stationary with respect to the movable electrode located on opposing sides of the movable electrode, and gaps provided between the movable electrode and the fixed electrodes. To prevent the movable electrode becoming fused to the contacted fixed electrode, in a first aspect of this invention, an insulating layer is provided between the movable electrode and fixed electrodes, the layer being either on the movable electrode or on the fixed electrodes and in a second aspect the movable electrode or, preferably, the fixed electrodes, are formed of a high melting point material. In such a second aspect, to improve adhesion between the high melting point material and a substrate to which the fixed electrodes are mounted, a lower melting point material is firstly coated on the substrates. A sensor detector unit processing circuit has the output characteristic of the circuit digitally adjusted by suitable switching of a plurality of resistors, and the sensor chip and the detector unit integrated circuit may be located on a common base and mounted in a hermetically sealed chamber to prevent adverse environmental effects affecting operation of the sensor and detector unit assembly. A gas having a dew point of -40.degree. C. or lower is, advantageously, charged into the hermetically sealed chamber.

Semiconductor acceleration sensor and vehicle control system using the

A capacitance type accelerometer, having a fist silicon plate formed a movable electrode which is moved according to acceleration, two second silicon plates which are disposed on both sides of the first silicon plate with a certain separation distance, and thermal oxide films which are respectively disposed between the first silicon plate except the movable electrode and the two second silicon plates and stick the first silicon plate except the movable electrode and the two second silicon plates together. And further, a capacitance type accelerometer, having, a silicon plate formed a movable electrode which is moved according to acceleration, glass plates respectively mounting a conductive layer thereon which are opposite to the silicon plate with a certain separation distance and are sticked to the both side of the silicon plate except the movable electrode and leading wires which are respectively connected to the conductive layers through a groove formed between the silicon plate and the glass plates respectively deriving. These capacitance type accelerometers are made by processing and cutting a wafer by dicing saw without coming into the accelerometer of cutting chips or cutting water.

An electrostatic type micro accelerometer comprising means for preventing permanent sticking between a movable electrode and a stationary electrode due to residual dielectric polarization, resisual electric charges and water adsorption and condensation around possible contacting portions therebetween when the movable electrode excessively displaces. The sticking preventing means is realized by disposing one of electric field reducing means, water adsorption and condensation reducing means and contacting area limiting means around the possible contacting portions.

Electrostatic type micro transducer and control system using the same

A signal processor (5) is coupled to a detector (6) for detecting a physical quantity. The signal processor has a zero adjustment memory (14) and a sensitivity adjustment memory (16). The zero adjustment memory and the sensitivity adjustment memory have a number of switches (20, 20A, 20', 20'), respectively. These switches are changed over digitally using a zener zapping method or a polysilicon fuse method at each switch to adjust the characteristics of the detector.

Sensor

In a capacitance type accelerometer used for an air bag system etc., a plurality of grooves crossing each other are provided on the surface of a movable electrode which is arranged to face a fixed electrode at a portion having a gap thereinbetween, and end portions of each groove open to an outside space at the portion between the movable electrode and the fixed electrode. The grooves can be provided on surface of the fixed electrodes. Ventilation between inside and outside of the facing portion is improved by opening of the grooves to outside space, and air damping which is caused at operation of the movable electrode at the gap between the electrodes is reduced, and, consequently, response speed of the movable electrode is increased.

Capacitance type accelerometer for air bag system

A capacitive type semiconductor accelerometer has an intermediate silicon plate of n type conductivity including a movable electrode constituting a pendulum mass formed within the intermediate silicon plate and supported thereby via a beam so as to permit movement in a direction perpendicular to its plane. A first conductive island is formed within the intermediate plate and is immovably supported thereby via a first insulating leg so as to be isolated therefrom, and an upper glass plate is anodic bonded to the intermediate silicon plate. A first stationary electrode is formed on the upper glass plate at the position facing one face of the movable electrode with a predetermined gap. A lower glass plate is anodic bonded to the intermediate silicon plate and a second stationary electrode is formed on the lower glass plate at the position facing the other face of the movable electrode with a predetermined gap. First, second and third pads are disposed in common on the lower glass plate at the outside of the intermediate silicon plate, the first pad being electrically connected to the first stationary electrode via a first thin film lead formed on the lower glass plate and the first conductive island, the second pad being electrically connected to the movable electrode via a second thin film lead formed on the lower glass plate and the intermediate silicon plate and the third pad being electrically connected to the second stationary electrode via a third thin film lead formed on the lower glass plate.

Capacitive type semiconductor accelerometer

Disclosed is an acceleration detector which has an electrically conductive mass portion formed at a free end of a cantilever, and fixed electrodes arranged opposite to the mass portion through a gap so that the value of acceleration is detected on the basis of the change of capacitance between the mass portion and the fixed electrodes, and in which at least one space is formed in the inside of the mass portion to lighten the weight of the mass portion to thereby widen the range of measurement.

Capacitive acceleration detector having reduced mass portion

A detector for detecting a physical quantity as a quantity of electricity has a detection portion, a portion for stimulating the detection portion and a signal processing portion, wherein a calibrating signal is supplied from the signal processing portion to the detection portion via the stimulating portion so as to measure a specific response of the detection portion whereby a self-calibration and a correction of the characteristics are performed in accordance with the amount of the change in the response.

An accelerometer having a movable electrode which is moved according to acceleration with respect to a fixed electrode disposed in opposition to the movable electrode. An output device generates an output voltage which is proportional to the acceleration by measuring a gap between the movable electrode and the fixed electrode. A pulse width modulator generates pulses, wherein a pulse width of the pulses is modulated according to the output voltage, and a feedback device feeds back an electrostatic force which is proportional to the pulse width of the pulses from the pulse modulator between the movable electrode and the fixed electrode. As the acceleration in the acceleration sensor is linearly detected, the acceleration sensor is easily adjusted.

Accelerometer with pulse width modulation

A capacitance type accelerometer, having a fist silicon plate formed a movable electrode which is moved according to acceleration, two second silicon plates which are disposed on both sides of the first silicon plate with a certain separation distance, and thermal oxide films which are respectively disposed between the first silicon plate except the movable electrode and the two second silicon plates and stick the first silicon plate except the movable electrode and the two second silicon plates together. And further, a capacitance type accelerometer, having, a silicon plate forming a movable electrode which is moved according to acceleration, glass plates respectively mounting a conductive layer thereon which are opposite to the silicon plate with a certain separation distance and are connected to both sides of the silicon plate except the movable electrode and lead wires which are respectively connected to the conductive layers through a groove formed between the silicon plate and the glass plates.

Light equipment is provided for irradiating the measuring object and forming light spot on it through the collimate lens. Reflected light from the measuring object is incident to the spatial filter through the objective lens for detecting the incidence position of the reflected light. A distance measuring circuit calculates contiuously the distance (d) between the objective lens and the measuring object by optical triangulation based on the output signal from the spatial filter. The frequency detecting circuit is connected to the spatial filter. When the sought running speed is V, the pitch between each equivalent light receiving element p, and the magnification of the optical image of the measuring object M, the frequency detecting circuit measures the frequency f which is given by the formula of F=MV/p. The calculator calculates the velocity V based on the output signal from the distance measuring circuit and on the output signal from the frequency detecting circuit.

Growing community of inventors

Mito, Japan

Shigeki Tsuchitani