Hitachi, Ltd.

Masanori Tanabe

Kanji Kawakami

Satoshi Shimada

Hiroshi Fukui

Moriaki Fuyama

Shinji Narishige

Motohisa Nishihara

Yoshitaka Matsuoka

Michitaka Shimazoe

Hideyuki Nemoto

Yutaka Sugita

Masaaki Hayashi

Kazuji Yamada

Akio Yasukawa

Kazuo Nakagoshi

Yokuo Saitoh

Katsuya Mitsuoka

Makoto Aihara

Masatoshi Tsuchiya

Mitsuo Ai

Yutaka Kobayashi

Makoto Saito

Yukio Takahashi

Hiroshi Ikeda

Yoshihiro Shiroishi

Kazuo Shiiki

Yasumasa Matsuda

Kazuhiro Nakamoto

Hajime Aoi

Takashi Kawabe

Makoto Morijiri

Hisao Okada

Yoshimi Yamamoto

Tadayuki Iwakura

Yasushi Shimizu

Masaaki Sano

Hirotsugu Fukuoka

Norifumi Miyamoto

Ko Soeno

Hideo Uzuhashi

Shigeyuki Kobori

Shunichiro Kuwatsuka

Takeo Nagata

Ichiya Sato

Takao Yoneyama

Yoshikazu Tsuji

Kouichi Shimizu

Soji Sasaki

Mitsuo Suda

Eiji Nakanishi

Eizi Ashida

Katsuya Katohgi

Shuji Sudo

Keiji Miyauchi

Ryozo Akahane

Mareo Suto

Shigeru Inose

A thin film magnetic head which can suppress magnetic saturation at opposite ends of width of a narrow track width to reduce the amount of recording side-fringing onto a recording medium and which can assure a necessary recording magnetic field satisfactorily. Also a magnetic disk apparatus using the head. A second magnetic yoke has a magnetic gap depth over which the spacing of a magnetic gap keeps substantially equal toward a rear portion of the second magnetic yoke, starting at the tip of a second magnetic pole and the spacing between a first magnetic yoke and the second magnetic yoke is increased toward the rear portion, starting at a position corresponding to the magnetic gap depth. The second magnetic pole of the second magnetic yoke has in the track width direction a width for recording a signal on a track width of the recording medium. The width keeps constant over a predetermined length toward the rear portion, starting at the second magnetic pole tip and spreads monotonically toward the rear, starting at a position corresponding to the predetermined length. The predetermined length terminating in the spread start position of the width of the second magnetic yoke is set to be shorter than the magnetic gap depth.

Thin film magnetic head and magnetic disk apparatus using the same

A magnetic disc apparatus has a large recording density of 120 megabits per square inch or more, and defines a relationship among a pole thickness (Pt) of thin-film magnetic heads disposed in the magnetic disc apparatus, and a saturation flux density (Bs) of cores of the heads and a recording wavelength (.lambda.) for the thin film magnetic discs have a coercivity of 1800 Oe or more, wherein a levitation space between the head and the disc is 0.15 .mu.m or less.

Large capacity magnetic disc apparatus with a particular relationship

A magnetic disc unit has a thin film magnetic head in which a lower magnetic core and an upper magnetic core form a magnetic circuit. The upper magnetic core is constructed by magnetic films having at least two layers. A saturation magnetic flux density of the inside magnetic film, of the magnetic films having at least two layers, facing a magnetic gap of the magnetic circuit is larger than that of the outside magnetic films of the upper magnetic core and the lower magnetic core.

Magnetic disc unit having a plurality of magnetic heads which include

In a magnetic disk device having a composite head with an induction type of recording head adjacent a magneto-resistance effect type of reproducing head, a read error relief is provided to relieve read errors caused by Barkhausen Noise or Base Line Shift phenomenon inherent to the magneto-resistance effect type of reproducing head. Upon occurrence of a read error, a re-try function is first executed, and a track offset function is executed for relief of the read error. However, if the read error is not relieved after the offset operation and the re-try operation have been performed a predetermined number of times, then a pseudo write-in and/or read current control operation is performed together with the offset operation and/or re-try operation for a predetermined number of times. The control operation varies the magnetic domain structure in the head magnetic film (MR film). The variation of magnetic field and/or read current in the head magnetic film causes the magnetic domain structure of the head magnetic film to be varied, so that the Barkhausen Noise or the Base Line Shift phenomenon are extinguished.

Magneto-resistance effect type of recording/reproducing head

A magnetic head for reading from and/or writing to a magnetic information storage medium has a substrate on which a plurality of thin films are formed in sequence. The films provide a magnetic circuit having a magnetic gap, a bottom pole piece and a top pole piece overlying said bottom pole piece. The top pole piece is formed as a tip portion adjoining the magnetic gap and a rear portion which makes magnetic contact with the tip portion. The rear portion is formed in the sequence after the tip portion. To ensure accurate thickness and width of the tip portion, a non-magnetic protective film is formed on the tip portion after the tip portion is formed and before the rear portion is formed.

Magnetic information storage apparatus including magnetic head and

A method of making a silicon diaphragm pressure sensor includes forming an oxide film on one surface of a monocrystalline silicon substrate. A polycrystalline silicon layer is formed on the oxide film. The oxide film may be partly removed before the formation of the polycrystalline silicon layer. The polycrystalline silicon layer is heated and melt to recrystallize the same, thereby converting the polycrystalline silicon layer into a monocrystalline silicon layer. On the monocrystalline silicon layer may be epitaxially grown an additional monocrystalline silicon layer. By using the oxide film as an etching stopper, a predetermined portion of the substrate is etched over a range from the other surface of the substrate to the oxide film, thereby providing a diaphragm of the pressure sensor.

Method of making silicon diaphragm pressure sensor

A tablet type coordinate input apparatus comprises a flat medium for propagating a longitudinal elastic wave, longitudinal elastic wave detecting elements disposed on part of the end-adjacent side surfaces or of the front surface of the flat medium, a longitudinal elastic wave input member having an end portion terminating in a sharp-pointed end and brought into pressure engagement at that end with any desired position on the surface of the flat medium to radiate the longitudinal elastic wave from that end, an amplifier circuit amplifying electrical signals indicative of the elastic wave detected by the detecting elements, a comparator circuit comparing the signals amplified by the amplifier circuit with a predetermined threshold voltage thereby generating delay pulse signals corresponding to the propagation times of the longitudinal elastic wave, a counter circuit counting the lengths of time elapsed from the time of radiation of the longitudinal elastic wave toward the flat medium as a result of pressure engagement of the input member therewith to the time of generation of the delay pulse signals, and a computing circuit computing the coordinates on the basis of the time signals applied from the counter circuit.

Tablet type coordinate input apparatus using elastic wave

The drain voltage of an IGFET having a channel responsive to the change in physical quantity to be measured is negatively fed back to the gate terminal of the IGFET. The negative feedback loop includes series connection of a first amplifier having an amplification factor larger than unity and a second amplifier having an amplification factor smaller than unity. The interconnection point between the first and the second amplifiers is connected to the output terminal. There is provided a stable, highly sensitive and highly reliable semiconductor sensor.

Feedback circuit for a semiconductor active element sensor

A differential pressure measuring transducer assembly including a measuring diaphragm formed of semiconductor material having gauge resistance elements on one surface thereof and a central boss area of large thickness and a peripheral support flange on the other surface thereof defining therebetween an annular portion of small thickness. The measuring diaphragm is attached at the peripheral support flange to a glass support member and a metallic support member formed with pressure conducting bores respectively communicating with each other. The metallic support member is formed of material having a Young's modulus substantially equal to that of the measuring diaphragm.

Differential pressure measuring transducer assembly

A strain gauge is formed on one main surface of a semiconductor single crystal substrate while an insulating oxide film is formed on the other main surface of the substrate. A metal junction layer including several layers inclusive of eutectic alloy layers is formed on the surface of the insulating oxide film and the thus prepared structure is mounted on a metal strain generator. By heating this assembly to temperatures approximating to the eutectic point of the eutectic alloy layer, the semiconductor substrate and the metal strain generator are joined together.

Method of producing semiconductor displacement transducer

A pressure transducer comprising a silicon diaphragm on which a semiconductor strain gauge is formed and which has a diaphragm portion deformable in response to a pressure, an insulating support which is made of borosilicate glass having the silicon diaphragm rigidly mounted thereon and which is provided with a pressure introducing hole in its central part, a metallic support which is cylindrical, which is made of an iron-nickel alloy similar in the thermal expansion coefficient to the borosilicate glass and on which the glass insulating support is rigidly mounted, and a metallic housing within which the integrated structure consisting of the silicon diaphragm, the glass insulating support and the metallic support is arranged; the silicon diaphragm, the insulating support and the metallic support being joined by the anodic bonding, the metallic support being rigidly welded to the metallic housing at its lower end part.

Pressure sensitive apparatus

A semiconductor substrate has a major surface, another major surface on the opposite side of the first major surface, a strain gauge stripe formed in the central portion of the second major surface by diffusing an impurity therein, and electrodes connected to the strain gauge stripes. These strain gauge stripes are spaced from the peripheral edge of the second major surface by a distance greater than 1/3 of the length of the same major surface. The first major surface of the semiconductor substrate is bonded to an elastic metal load plate.

Semiconductor strain gauge with elastic load plate

A semiconductor pressure transducer comprising a disc-shaped pressure-responsive diaphragm; a pair of radial strain gauge units having a piezoresistance effect, formed by injecting an impurity in the radial direction in the surface of the diaphragm; and a pair of tangential strain gauge units having a piezoresistance effect, formed by injecting an impurity in the tangential direction in the surface of the diaphragm, wherein the distance from the pair of the radial strain gauge units to the center of the circular diaphragm is greater than the distance from the pair of the tangential strain gauge units to the center of the circular diaphragm.

Semiconductor pressure transducer

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Hitachi, Japan

Masanori Tanabe