Honda Motor Co., Ltd.

Nagano Keiki Co., Ltd.

Nagano Keiki Seisakusho, Ltd.

Shigemitsu Ogawa

Munenori Tsuchiya

Eiji Mutoh

Daiji Uehara

Kenji Nagasawa

Fujito Tanaka

Kazuya Yamagishi

Akihiro Niiya

A processor of a signal processing circuit for calibrating an electro-capacitance pressure sensor includes a coefficient arithmetic section for calculating calibration value and a calibration arithmetic section. The calibration arithmetic section calculates an electro-capacitance ratio between electro-capacitance C and C detected by an electro-capacitance pressure sensor and conducts a calibration calculation from the electro-capacitance ratio to output a converted pressure value. The processor includes a fundamental arithmetic section for conducting a calculation given by f&equals;(Z&minus;W)/(X&minus;Y) for predetermined arguments X, Y, Z and W input by the coefficient arithmetic section or the calibration arithmetic section and for outputting the calculation result f to the one of the coefficient arithmetic section and the calibration arithmetic section providing the input. The fundamental arithmetic section provides shared calculating for the coefficient calculation and calibration calculation.

Signal processing circuit of sensor

A self-calibrating sensor includes a sensor element for electrically detecting change in physical amount of a workpiece. A signal output device detects changes of the sensor element to output an electric signal. A processor conducts calibration calculation for the electric signal to adjust to the physical amount of the workpiece. A memory stores calculation results of the processor. The processor includes a calibration value calculating circuit for calculating a calibration value by conducting the calibration calculation based on a predetermined transforming formula and a calibration completion determining circuit for determining whether calculation of the calibration value by the calibration value calculating circuit is completed or not. The presence of the calibration value calculating circuit and the calibration completion determining circuit eliminates the need for connecting to an outside computer through an exclusive line for calculating the calibration value. Accordingly, an exclusive I/O line for calibration work is omitted as compared to conventional self-calibrating sensors.

Self-calibrating sensor

A pressure sensor based on electrostatic capacity method is disclosed, which comprises the main body of a pressure sensing element having one end surface as a pressured face and the other end surface as a back, for detecting the pressure of a measurement fluid acting on the pressured face, a seal member, a measure pattern on the back, and a one-chip IC. For size reduction, an input-output policy is provided near the main body of the pressure sensing element, and it effects input and output with respect to the pressure sensing element main body while preventing external disturbances and improving the accuracy of measurement.

Pressure sensor

A pressure sensor of electrostatic capacitance type is disclosed, which detects the pressure of a measurement fluid acting on a pressured surface of an elastic diaphragm from a change in the electrostatic capacitance between opposed electrodes provided on opposed surface of a ceramic base and the elastic diaphragm. The base side electrode comprises a plurality of division electrode one enclosing the next inner one. Of these division electrodes the outermost one is grounded or held at a predetermined voltage, or it is covered by overcoat glass, and thus it is imparted with a function of stabilizing the measurement value. In an electrode hole for leading an electrode to the outside, a path is formed for leading atmospheric air or like fluid providing for the reference pressure for pressure measurement into the space defined between the base and elastic diaphragm.

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Tokyo, Japan

Shigemitsu Ogawa