Sumitomo Electric Industries, Limited

Makoto Otsuki

Kaoru Murabe

Osamu Komura

Hisao Takeuchi

Tetsuya Inoue

Tetsuichi Yokota

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

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

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

To provide a hydrodynamic bearing, small in size and light in weight, and yet simple in structure and inexpensive in cost, which can exhibits a sufficient rigidity. The bearing is structured so as to comprise a radial bearing portion including a groove capable of introducing fluid such as air, and a thrust bearing portion whose one end is connected with the radial bearing portion and whose other end is open to the outside, whereas the structure guides a fluid introduced at the radial bearing portion to the thrust bearing portion and utilizes a pressure at the thrust bearing portion, thereby obtaining a stable thrust force without separately disposing a thrust hydrodynamic pressure generating mechanism. The fluid introduced to the thrust bearing portion is thereafter discharged through an opening linked with outside. The surface area size of the groove is preferably 40% or less to the surface area size of the radial bearing portion as a whole, and the number of such grooves is preferably six or smaller. Where the shape of the groove is an asymmetric shape that the depth is deep in an upstream portion of an airflow but shallow in a downstream portion (aft side), the radial bearing portion and the thrust bearing portion are improved in rigidity.

Dynamic pressure bearing and spindle motor with the bearing

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

A hydrodynamic gas bearing structure includes a fixed shaft, a hollow cylindrical sleeve opposing to the fixed shaft with a radial space kept therebetween, and a thrust plate having an opposing surface opposing to an end surface in the axial direction of the sleeve. The opposing surface of the thrust plate has a groove for generating dynamic pressure between the sleeve and the thrust plate, a protruded portion formed at an inner peripheral portion, and a recessed portion formed shallower than the groove, extending from the protruded portion toward an outer peripheral portion. Top surface of the protruded portion is at a position of a first height from the bottom of the recessed portion, and the outer peripheral portion of the opposing surface includes a portion at a position of a second height lower than the first height from the bottom of the recessed portion.

Hydrodynamic gas bearing structure

The disclosed method of making a compound semiconductor single-crystalline substrate for liquid phase epitaxial growth has a relatively low cost and excellent practicality. The compound semiconductor single-crystalline substrate is prepared to have a surface roughness of at least 1 .mu.m and not more than 10 .mu.m as measured over a line of 1 mm length. This substrate is employed as a substrate for an epitaxial wafer for an infrared- or visible light-emitting diode. Due to its particular roughness, the substrate can be prevented from slipping or falling while it is transported during processing. Furthermore, no lapping and polishing are required for manufacturing the substrate. Thus, the substrate for liquid phase epitaxial growth can be provided at a relatively low cost.

Method of making compound semiconductor single-crystalline substrate for

The disclosed compound semiconductor single-crystalline substrate for liquid phase epitaxial growth has a relatively low cost and excellent practicality. This compound semiconductor single-crystalline substrate has a surface roughness of at least 1 .mu.m and not more than 10 .mu.m as measured over a line of 1 mm length. This substrate is employed as a substrate for an epitaxial wafer for an infrared- or visible light-emitting diode. Due to its particular roughness, the substrate can be prevented from slipping or falling while it is transported during processing. Furthermore, no lapping and polishing are required for manufacturing the substrate. Thus, the substrate for liquid phase epitaxial growth can be provided at a relatively low cost.

Growing community of inventors

Itami, Japan

Makoto Otsuki