Fuji Electric Co., Ltd.

Teizo Takahama

Mitsuru Tamai

Kimihiro Nakamura

Mikihiko Matsuda

Toyoki Kazama

Toshiyuki Takano

Masahiko Masuda

Keisuke Sugimoto

Yuji Sugiyama

Tadanori Yuhara

Takeo Tanaka

Hideo Shiraishi

Yoshiteru Yoshida

Ryuji Hanafusa

Tatumi Hieda

Kazuaki Kitamura

Shinichi Souma

A small, light and portable sensor for detecting and quantifying a harmful high molecular weight substance present in a sample gas in trace amounts is herein disclosed. In the sensor, light and heavy ions are formed by ionizing molecules of the sample gas components in an ionization region. The heavy ions are formed through an ion-molecule reaction. The passage of ions through an ion-passage control region is controlled by directly or indirectly controlling the electric field established between a central electrode and a counter electrode The ions which pass through the control region are collected on a collector electrode. The high molecular weight substance is detected and quantified on the basis of the output from the collector electrode.

Sensor for detecting a high molecular weight substance using ionization

The present invention is directed to a capacitive differential pressure detector comprising a diaphragm disposed between two electrodes. In a first embodiment, each of the electrodes comprises two conductive plates with an insulator disposed therebetween. Step-like portions are formed in the conductive plate nearest the diaphragm. In a second embodiment, the plate nearest the diaphragm is insulative with a conductive film formed thereon. In a third embodiment, at least one groove is formed in the plate nearest the diaphragm. The groove is formed in a surface of the plate which faces the diaphragm. The groove also intersects a pressure guide hole. In a fourth embodiment, a substrate is disposed on a surface of the plate farthest from said diaphragm. In a fifth embodiment, an insulating layer has the same coefficient of thermal expansion as the conductive plates. In a sixth embodiment, the diaphragm is etched in order to form a circular flexible part, a centrally disposed displacing part, and a bonding part.

Capacitive differential pressure detector

A pressure detector for measuring the pressure of a pressurized fluid by means of electrostatic capacitance comprising a diaphragm displaceable in response to the pressure, and a pair of fixed electrodes, one of each of the fixed electrodes being located on each side of the diaphragm and being electrostatically capacitively coupled to the diaphragm, each of the fixed electrodes being shaped to essentially eliminate electrostatic capacitances that are not differentially linear with respect to the pressure.

Electrostatic capacitance type pressure detector

An electrostatic capacity type pressure detector having a central diaphragm, which is deformed by pressure, and a fixed electrode on each side of the diaphragm. Each of the fixed electrodes includes a first electrically conductive plate confronting the diaphragm, an insulating plate joined to the first conductive plate, and a second electrically conductive plate joined to the first plate. An annular support joined to the diaphragm and to the insulating plate surrounds but is insulated from the first electrically conductive plate. A hole in the electrode introdues pressure into a space defined by the electrode and the diaphragm.

Electrostatic capacity type pressure detector

A limited current type oxygen sensor comprises an oxygen ion conductive solid electrolyte, a detection element including a positive electrode and a negative electrode, and a heater element including a heater. The negative electrode is installed on one of the walls constituting a space communicating with a small hole for restricting the amount of oxygen to diffuse therethrough. The porous positive electrode and the heater are embedded in the oxygen ion conductive solid electrolyte layers.

Oxygen sensor

A limited current type oxygen sensor comprises a solid electrolyte element formed from material having high oxygen-ion conductivity such as yittria-stabilized zirconia. Electrodes are provided on the top surface and the bottom surface of the element and are formed by calcining a mixture of small ceramic particles that are relatively sinter-retardant as compared with oxygen-ion conducting ceramics, of 200 .ANG. in average particle size fine precious metal particles, and a binder. A cover is provided over the second electrode and the cover includes at least one diffusion orifice that permits ambient gas to diffuse toward the second electrode. The dry-gas-based and humid-gas-based oxygen content of the gas is determined by applying a first voltage less than the theoretical water decomposition voltage and a second voltage greater than the theoretical water decomposition voltage to the electrodes to generate corresponding currents associated with the oxygen-ions which flow through the electrolyte element between the first electrode and the second electrode. A heater may be buried in the electrolyte element to increase the flow rate of oxygen ions between the electrodes.

A carbon monoxide detecting apparatus is provided which is substantially unaffected by other coexisting gases in the gas atmosphere being sampled. The present invention includes a first carbon monoxide detecting element, a second carbon monoxide detecting element, and a comparing means. The first carbon monoxide detecting element is responsive to carbon monoxide gas and produces a stepwise change in a first film current over a first preselected range of carbon monoxide gas concentration. The second carbon monoxide detecting element is responsive to carbon monoxide gas and produces a stepwise change in a second film current over a second preselected range of carbon monoxide gas. The comparing means is responsive to the first and second film currents and provides an output difference signal .DELTA.E. The amplitude of the output difference signal .DELTA.E is in accordance with the absolute value difference between the first film current and the second film current. The two preselected ranges of carbon monoxide gas concentration can be achieved by appropriately altering the structure of the respective carbon monoxide detecting element and/or by making the substrate temperatures of the two carbon monoxide detecting elements different.

Carbon monoxide detecting apparatus

A carbon monoxide detecting device which exhibits a stepwise change in film current over a preselected range in carbon monoxide concentration is disclosed. According to the present invention, in one embodiment, a first film predominantly of stannic oxide (SnO.sub.2) is formed on an insulating layer, and a second film predominantly of platinum (Pt) is formed on said first film. The second film is of an average film thickness of about 0.3 to 30 platinum atom layers. In another embodiment, gold (Au) is incorporated into said second film, and the second film is of an average film thickness of about 0.3 to 30 platinum atoms and the amount of gold ranges up to 50 atomic percent of the amount of platinum. In a third embodiment, a donor selected from the group consisting of antimony (Sb) and bismuth (Bi) is incorporated into the first film, and an intermediate film predominantly of stannic oxide (SnO.sub.2) having an acceptor selected from the group consisting of platinum (Pt), aluminum (Al), and boron (B) is formed intermediate said first and second films. The first, intermediate, and second films are formed, for example, by a high frequency reactive sputtering method.

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Kanagawa, Japan

Teizo Takahama