Hitachi, Ltd.

Hitachi Car Engineering Co., Ltd.

Other

Hitachi, Ltd. and Hitachi Car Engineering Co., Ltd.

Akihiko Saito

Satoshi Shimada

Masahiro Matsumoto

Keiji Hanzawa

Atsushi Miyazaki

Norio Ichikawa

Junichi Horie

Seikou Suzuki

Seiji Kuryu

Yasuo Onose

Akio Yasukawa

Atsuo Watanabe

Tatsuo Horiba

Masahisa Inagaki

Yasuhisa Aono

Hiroshi Moriya

Hideyo Kodama

Terumi Nakazawa

Toshinori Dozono

A sensor adjusting circuit for adjusting a digital sensor, whose circuit scale is small and which can maintain high accuracy in a wide adjustment range is provided. A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor and outputting it as another analog output signal in accordance with a physical quantity to be sensed, comprises: a first analog-to-digital converter having an analog integrator () for integrating the analog input signal, a comparator () for comparing an output of the analog integrator with a predetermined value, and a D/A converter () for outputting an output of the comparator as the input signal; and a second digital-to-analog converter () for converting the output of the comparator and outputting it as the analog output signal.

Sensor adjusting circuit

A sensor with built-in circuits can be improved in the stability of the operation or characteristics. A circuit region and a sensor region are covered by a passivation film. The sensor region is partially covered by the passivation film. The sensor region and circuit region are protected by the passivation film, and an effect of the passivation film on the mechanical displacement of a diaphragm portion can be alleviated so that the sensor with built-in circuits may be improved in the stability of the operation or characteristics.

Sensor with built-in circuits and pressure detector using the same

By sealing a diaphragm with less processes and lower cost and reducing deformation due to remaining stress, a stable and highly reliable pressure sensor construction is proposed. The pressure sensor is low in measurement error and small in floating capacitance and leakage current and good in characteristic. As a means to attain the above object, a polycrystalline silicon diaphragm is sealed with a silicon oxide film deposited through a LPCVD method and then completely covered. The diaphragm is placed on a surface of a semiconductor substrate with a nearly constant gap of 0.15 to 1.3 &#x3bc;m, and has difference-in-grade constructions of a deformation reducing means due to remaining stress.

Capacitive type pressure sensor

Dynamic quantitative displacement is converted stably and straight into voltage (D.C. output) by using a high speed detection driving frequency without restricting a response of an operational amplifier. When a dynamic quantity detection electrostatic capacitance changes according to a dynamic quantity, electric charges stored in this element and in a reference electrostatic capacitance become unbalanced to produce a difference value, and an output of an operational amplifier changes according to the difference in electric charge quantity. However, the output becomes finally stable when the electric charges in the dynamic quantity detection electrostatic capacitance and in the reference electrostatic capacitance become equal. The output is proportional to a reciprocal of the dynamic quantity detection electrostatic capacitance and it is a D.C. voltage. Further, output without depending on integration feedback capacitance (feedback condenser) CF can be obtained.

Electrostatic capacitance type dynamical quantity sensor

A sensor adjusting circuit for adjusting a digital sensor, whose circuit scale is small and which can maintain high accuracy in a wide adjustment range is provided. A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor and outputting it as another analog output signal in accordance with a physical quantity to be sensed, comprises: a first analog-to-digital converter having an analog integrator (,) for integrating the analog input signal, a comparator (,) for comparing an output of the analog integrator with a predetermined value, and a D/A converter (,) for outputting an output of the comparator as the input signal; and a second digital-to-analog converter (,) for converting the output of the comparator and outputting it as the analog output signal.

In a capacitance type pressure sensor, a diaphragm is formed of a fragile material using an impurity-diffused monocrystal silicon and constitutes a stable pressure-responsive structure which does not undergo a plastic deformation. Between the diaphragm and a movable electrode is formed an oxide film to diminish stray capacitance between the movable electrode and a substrate and also between the movable electrode and a impurity-diffused layer. The oxide film and the movable electrode are each divided into plural regions so that the divided regions of the movable electrode are formed on the divided regions of the oxide film, thereby diminishing stress strain induced by a difference in therm expansion coefficient among the diaphragm, oxide film and movable electrode. The upper surface of a fixed electrode is covered with a structure for the fixed electrode which structure is formed by an insulating polycrystal silicon film not doped with impurity whereby the rigidity of the electrode is enhanced and it is possible to diminish a leak current.

Capacitance type pressure sensor with capacitive elements actuated by a diaphragm

A semiconductor pressure sensor utilizing electrostatic capacitance has a plurality of pressure sensing electrostatic capacitances and a reference electrostatic capacitance formed on one side of a silicon chip. As a movable electrode, the pressure sensing electrostatic capacitances each have a diaphragm, which may have a displacement portion composed of a central area thereof, and a peripheral portion which is more deformable than the central portion.

Semiconductor pressure sensor including reference capacitor on the same

A non-aqueous secondary battery having a long life-time and a high capacity density is provided by increasing the discharging capacity of the negative electrode and extending the life-time of the negative electrode. The nonaqueous secondary battery has a positive electrode and a negative electrode reversibly absorbing and discharging an alkaline metal and a nonaqueous electrolyte, wherein the negative electrode is made of an inter-metallic compound containing at least one element selected from the group consisting of 4A group elements, P and Sb, the inter-metallic compound has any one of CaF.sub.2 type, ZnS type and AlLiSi type crystal structures, and the CaF.sub.2 type structure is any one an inverse-fluorite structure and a fluorite structure having a lattice constant larger than 6.36 .ANG..

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Hadano, Japan

Akihiko Saito