Sumitomo Electric Industries, Limited

Other

Canon Kabushiki Kaisha

Director General Agency of Industrial Science and Technology

Hiroyasu Funakubo & Sumitomo Elec. Ind., Ltd.

Life Technology Research Found.

I. Sumitomo Electric Industries, Ltd.

Osamu Komura

Kaoru Murabe

Makoto Otsuki

Akira Yamakawa

Hisao Takeuchi

Masaya Miyake

Matsuo Higuchi

Tetsuya Katayama

Kenji Matsunuma

Eiji Kamijo

Norio Yasuoka

Tomoyuki Awazu

Michimasa Miyanaga

Mikio Nakasugi

Taku Fukita

Osamu Yamada

Chihiro Kawai

Mitsue Koizumi

Isshin Sato

Yoshinari Miyamoto

Masaaki Honda

Yasushi Ito

Takao Nishioka

Akira Kuibira

Akira Yamaguchi

Yasushi Tsuzuki

Yasushi Mochida

Takehisa Yamamoto

Jin-Joo Park

Jin-Joo Matsui

Hiroyasu Funakubo

Hitoyuki Sakanoue

Yukio Sekiguchi

Noboru Uchimura

Tatsuji Matsui

This invention provides a hydrodynamic bearing assembly which realizes a high rotation rate in a stable manner with robust rigidity. The hydrodynamic bearing assembly has a total radial gap of 3 microns or less for preventing contact with the thrust bearing. The thrust bearing is a pump-out type, and the radial bearing has offset grooves on the surface thereof to supply fluid flow to the thrust bearing. A depth ratio of the grooves relative to the diameter of the shaft is preferably 0.005 or less to avoid reduced translational rigidity.

Hydrodynamic bearing assembly

The invention provides porous silicon nitride ceramics that having uniform, fine closed pores and a manufacturing method thereof. Metal Si powder is mixed with a sintering additive, followed by thermal treatment, which is a pre-process for forming a specific grain boundary phase. Two-stage thermal treatment is thereafter performed by microwave heating at a temperature of 1000&#xb0; C. or more. The metal Si powder is thereafter subjected to a nitriding reaction from its surface, the metal Si is thereafter diffused to nitride formed on the outer shell thereof such that porous silicon nitride ceramics having uniform, fine closed pores can be produced. Having a high ratio of closed pores and being superior in electrical/mechanical characteristics, the porous silicon nitride ceramics can display excellent characteristics if used, for example, for an electronic circuit board that requires an anti-hygroscopicity, a low dielectric constant, a low dielectric loss, and mechanical strength.

Porous silicon nitride ceramics and method for producing the same

This invention is to provide a hydrodynamic bearing assembly, which realizes the high rotation rate in a stable manner and the robust rigidity. The hydrodynamic bearing assembly has a total radial gap of 3 microns or less for preventing the contact in the thrust bearing. The thrust bearing is a pomp-out type one, and the radial bearing has offset grooves on the surface thereof to supply the fluid flow sufficiently to the thrust bearing. The grooves also eliminate a half-whirl. A depth ratio relative to the diameter of bearing is preferably 0.005 or less to avoid the reduced translation rigidity. The radial gap is smoothly enlarged from the center to both ends along the axis, and the shaft is biased to incline the shaft relative to the sleeve, so that the shaft can be rotated with the robust rigidity. Also, a pair of the thrust bearings is provided on both ends of the radial bearing so as to realize the robust rigidity.

Hydrodynamic bearing assembly and spindle motor having the same

A bearing having a high thrust rigidity, an excellent vibration resistance, and a simple structure, as well as a spindle motor using such a bearing are provided. A groove or groovesare disposed to either one of a shaftand a sleevewhich form a radial bearing portion, to thereby exert thrust force in a direction which brings two mutually facing members at a thrust bearing portion closer to each other. The grooveis inclined with respect to an axis, and the inclination exerts, between the shaftand the sleeve, thrust force in a thrust direction. The groovemay be herringbone-shaped or other type of groove which can generates such thrust force. It is also possible to further enhance the thrust force utilizing a negative pressure, with an upstream side of the radial bearing portion for introducing fluid such as air shielded from outside air.

Dynamic-pressure bearing and spindle motor comprising the same

Powder of a metal serving as a precursor for ceramics ( ) and a sintering additive are mixed with each other and heat-treated by microwave heating thereby nitriding or oxidizing the metallic powder from the surface thereof and diffusing the metal with a nitride or an oxide formed on the shell of the metal for obtaining porous ceramics ( ) having homogeneous and fine closed pores ( ). The porous ceramics ( ) according to the present invention, having the closed pores ( ) homogeneously diffusing at a high ratio, exhibits excellent characteristics when applied to an electronic circuit board or the like requiring moisture absorption resistance, low permittivity and low dielectric loss as well as mechanical strength.

Porous ceramics and method of preparing the same as well as microstrip substrate

A spindle motor includes a fixed base member, an outer cylindrical member made from a hollow tube, and an inner cylindrical member inserted in said outer cylindrical member. The inner and outer cylindrical members are arranged so that one of the outer and inner cylindrical member is fixed to the base member and the other is rotatable about a longitudinal axis thereof. A bearing assembly is provided for bearing the rotatable cylindrical member on the fixed cylindrical member. Also, drive means is provided for rotating the rotatable cylindrical member about the fixed cylindrical member. In particular, the fixed cylindrical member is made of ceramic.

Spindle motor and hard disc drive incorporating the same

A hydrodynamic bearing assembly with improved activation features is provided. The opposing surfaces in the radial and thrust bearings have grooves and with depths shallower gradually towards the downstream flow of the fluid passing therethrough, for generating the uniform dynamic pressure distribution. This allows the dynamic pressure distribution to be leveled so as to increase the bearing supporting force and prevent the dew grom being generated. Any one or both of the opposing surfaces in the thrust bearing has the inclined surface from the inner portion towards the outer portion so that the gap between the opposing surfaces is extended to about 2 microns. This causes the contacting points thereof when halted to be closer to the axis so that the friction can be reduced and the driving torque can be reduced when restating the bearing assembly. This also prevent the contact in the thrust bearing due to the external oscillating motion. Further, a second thrust plate is secured on the other end surface of the sleeve opposite to the thrust plate so that the total weight of the rotational member is supported between the second thrust plate and the end surface of the shaft when halted, thereby reducing the friction at the time of activating.

Dynamic pressure bearing with improved starting characteristics

A hydrodynamic gas bearing structure and a hard disk drive (HDD) including a hydrodynamic gas bearing structure are provided in which electrostatic charge built up in the rotatable components is safely discharged to the fixed components. A conductive structure is installed between the rotatable and fixed components at or in the vicinity of the axis of rotation of the rotatable components. The conductive structure provides a safe discharge path for electrostatic charge dissipation. The conductive structure located at or in the vicinity of the axis of the rotation is barely influenced by the relative rotation between the rotatable and fixed components as well as air flow for generating hydrodynamic pressure. The conductive structure can be a magnetic fluid or a conductive, flexible strip. In a HDD a dummy disk and a dummy head are provided to dissipate electrostatic charge.

Bearing structures, spindle motor, and hard disk drive

There is provided a means for preventing wear caused by the contacting/sliding of a thrust hydrodynamic gas bearing surface when a spindle motor is started. A cylinder of a radial hydrodynamic gas bearing that has radial hydrodynamic grooves in an outer circumferential surface thereof and a disk of a thrust hydrodynamic gas bearing that has thrust hydrodynamic grooves in an upper face thereof are disposed on an upper end of an axial center of a stator core having a stator around which a motor coil is wound, a hollow cylinder whose inner surface facing the cylinder of the radial hydrodynamic gas bearing is smooth and a rotor magnet facing the motor coil are disposed on a hub acting as a rotational member, a load in a radial direction is supported by the radial hydrodynamic gas bearing, and a load in a thrust direction is supported by using the thrust hydrodynamic gas bearing together with a magnetic bearing consisting of the stator and the rotor magnet

Spindle motor

Provided is a durable spindle motor with a precise rotation but free from a shaft vibration, a decrease of rotation accuracy or a contact due to a swing during rotation. A shaft ( ) is inclined relative to a sleeve ( ) by an external biasing force, generating and then utilizing a hydrodynamic pressure generated during the rotation. The sleeve ( ) has a central cylindrical section (C) extending parallel to the axis and two tapered sections (A), (B) each connect(d with the cylindrical section (C) at its opposite ends and enlarged outwardly, so that a dynamic force is generated between the tapered sections (A), (B) and the shaft ( ). Preferably, an inclination of the tapered sections (A), (B) is identical to that of the shaft ( ), and lengths of the tapered sections (A), (B) is one fourth of that of the sleeve ( ). Similar advantages can be attained in an arrangement in which the sleeve ( ) is defined in the form of cylinder while the shaft ( ) is defined at its peripheral center with cylindrical section (c) and at its opposite ends with tapered sections (a), (b).

Hydrodynamic bearing and spindle motor

A hydrodynamic gas bearing structure includes a columnar shaft body ( ) and a hollow cylindrical bearing body ( ) arranged opposing the shaft body ( ) with a space ( ) maintained in the radial direction therebetween. In a cross section perpendicular to the central axis of the shaft body ( ) and the bearing body ( ), either the shaft body ( ) or the bearing body ( ) has a convex polygonal shape with at least ten vertexes. Accordingly, a hydrodynamic gas bearing structure can be obtained in which whirl can be suppressed even at a high speed rotation of 20,000 rpm or higher and run out associated with the rotation can be suppressed.

Hydrodynamic gas bearing structure

A complex bearing assembly has a sleeve and a shaft inserted in the sleeve. The shaft is rotatably supported in the sleeve through radial and axial bearings, i.e., hydrodynamic bearing and magnetic bearing. In particular, the axial bearing includes first and second magnetic members or magnet rings. The first magnetic member is secured on the shaft in a coaxial fashion, but the second magnetic ring is secured on the sleeve in an eccentric fashion. This causes an eccentric bias that forces the rotating shaft to a certain radial direction, allowing the rotating shaft becomes to lose frictional contacts with the sleeve at lower rotational number. This in turn decreases wears of the sleeve and the shaft, increasing the durability of the bearing assembly.

Spindle motor and complex bearing assembly for use with the spindle motor

Hydrodynamic gas bearing structure and optical deflection scanner

Growing community of inventors

Itami, Japan

Osamu Komura