Hitachi, Ltd.

Hitachi Instrument Engineering Co., Ltd.

Yutaka Sakurai

Tamio Ishihara

Masao Fukunaga

Takeo Nagata

Masatsugu Arai

Akiomi Kohno

Kazuaki Yokoi

Satoshi Shimada

Hiroyasu Uchida

Yuji Yoshitomi

Akira Sase

Yoshitaka Matsuoka

Akira Nagasu

Yuuji Yoshitomi

Mitsuo Ai

Kouji Saito

Yosimi Yamamoto

Yoshikatsu Satomi, Deceased

Shigeo Nishino

Souzo Fujimoto

A capacitance type electromagnetic flowmeter whose output is relatively free from fluctuations caused by external vibrations has a flow tube supported in a casing member by means of members having elasticity and viscosity (e.g., O-rings). Magnetic parts such as coils and a core are fixed to the casing member so as to define a space therewith, and protective rings are kept liquid-tight with respect to the flow tube by O-rings interposed therebetween. The equivalent mass of the flowmeter section vibrating integrally with the flow tube is reduced to increase the resonance frequency. Further, since the flow tube is insulated from vibrations of the protective rings, the flow is less subject to vibrations, thereby decreasing fluctuations in output due to external vibrations.

Capacitance type electromagnetic flowmeter

An electromagnetic flow meter for industries includes a transducer and a signal processor provided separately from the transducer. The transducer having an exciting circuit, an amplifying and calculating part and a transmitting part outputs an analog flow rate signal and digital signals which are superimposed to the an analog flow rate signal to the signal processor. The analog signal sent to the signal processor is passed through the signal processor without receiving any signal processing and the digital signals are sent into the transducer or taken into the signal processor through alternating current coupling means. The data transmission is diagnosed by checking the conformity between the data stored in the signal sending part and the received data. Data set in a data setting part provided in the signal processor are sent to the transducer through a transmitting cable in which the flow rate data are also transmitted.

Electromagnetic flow meter

An electromagnetic flow meter comprises a ceramic measuring pipe formed into a straight cylinder through which fluid to be measured flows, electromagnetic field generating device disposed adjacent to a central portion of an outer surface of the central portion of the ceramic measuring pipe for generating an electromagnetic field into a radial direction of the ceramic measuring pipe, electrodes for detecting an electric potential generated in the fluid, a case which accommodates the ceramic measuring pipe, the electromagnetic field generating device and the electrodes, and sealing members which are disposed between inner surfaces of the flanges of the case and ends of outer circumference of the ceramic measuring pipe. The case has a length longer than that of the ceramic measuring pipe and flanges at both ends thereof. Inner diameters of the flanges are slightly larger than an outer diameter of the ceramic measuring pipe. Portions of the sealing members outwardly project over the end surfaces of the flanges of the case.

An electromagnetic flowmeter comprises a ceramic measuring tube through which fluid to be measured flows, a pair of electromagnetic coils disposed on the outer surface of the measuring tube in the central region thereof at diametrically opposite positions and generating a magnetic field in a direction perpendicular to the direction of flow of the fluid, a pair of measuring electrodes fixed to the outer surface of the measuring tube in the central region thereof at diametrically opposite positions and having electrode axes perpendicular to both the direction of flow of the fluid and the direction of the magnetic field, and a pair of metallic shields fixed to the outer surface of the measuring tube in surrounding relation to the measuring electrodes. A pair of the measuring electrodes and a pair of the metallic shields are fixed to the ceramic measuring tube by a reaction product due to an interface reaction with the ceramic measuring tube under heating.

Electromagnetic flowmeter and manufacture method of same

An electromagnetic flowmeter for measuring the flow rate of a fluid. The flowmeter has a measuring tube made of ceramics and defining a fluid passage therein for the fluid, electrodes having ends exposed to an interior of the measuring tube through holes which are formed in a wall of the measuring tube, a magnetic field generating device disposed around the electrodes, and a case encasing the measuring tube, the electrodes and the magnetic field generating means. A ratio t/R between a wall thickness t and a mean radius R of the measuring tube is determined such that stress generated in the measuring tube by the fluid in the measuring tube does not exceed the rupture stress of the measuring tube. The measuring tube can have flanges on both axial ends thereof, a radial height of the flange from an outer surface of the measuring tube is not greater than the wall thickness of the tube when the tube is made of Al.sub.2 O.sub.3 and not greater than a value three times as large as the tube wall thickness when the tube is made of Si.sub.3 N.sub.4. The electrodes may be made from Ni or an Ni alloy and are secured to the measuring tube by press-fitting into holes formed in the tube wall or by jointing. The electromagnetic flowmeter thus obtained exhibits high strength and reliability and high degree of gas-tightness in the tube portions around the electrodes.

Electromagnetic flowmeter

In an apparatus for checking patterns on printed circuit boards by comparing two patterns formed on two printed circuit boards, registration patterns each including orthogonal straight line segments and respectively formed on the two printed circuit boards are imaged by two imagers, and registration images from the imagers are matched by means of a registration unit to accurately match an image of a pattern to be checked on one printed circuit board with an image of a reference pattern on the other printed circuit board.

Apparatus for checking patterns on printed circuit boards

A pressure transducer is arranged to mount a semiconductor pressure sensor in a housing such that the pressure of a high-pressure fluid is applied to one side of the semiconductor pressure sensor through a high pressure seal diaphragm and a sealed liquid in the high pressure side, while the pressure of a low-pressure fluid is applied to the other side of the sensor through a low-pressure seal diaphragm and a sealed liquid in the low pressure side, and a protecting member is provided closer to the low-pressure seal diaphragm.

Pressure transducer

A differential pressure transducer having a cantilever and a semiconductor strain gauge attached to each side of the cantilever at an intermediate portion of the latter. The cantilever has one end fixed by electron beam welding to a fixing member and the other end left for free displacement in response to a differential pressure. The displacement of the other end of the cantilever is detected as changes in the electric resistances of the semiconductor strain gauges.

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Katsuta, Japan

Yutaka Sakurai