A fluid dynamic bearing device which exhibits high bearing performance at low cost has a highly accurate bearing gap. At least a region in the outer circumferential surface of a shaft, which faces the radial bearing gap, is constituted of an electroformed part, and the region of the shaft excluding the electroformed part is constituted of a resin portion.

Fluid dynamic bearing device

A hydrodynamic bearing device is provided for use with a spindle motor. The hydrodynamic bearing device has a sleeve made of a sintered metal that is obtained by sintering a sintering material that is iron, an iron alloy, copper, a copper alloy or a mixture thereof. This sintered metal has independent pores, which do not communicate with each other, by selecting conditions for forming a desired sintered body within a predetermined range. The conditions includes a grain size of powdered metal of a material for the sintered metal, a molding pressure when the molded body is formed, sintering temperature and sintering period in the sintering step.

Hydrodynamic bearing device

Low-profile spindle motor whose entire shaft length is utilized to configure, along an encompassing sleeve, a radial dynamic-pressure bearing section. One end of the shaft is unitary with the rotor, and a cover member closes the other end. Between the sleeve upper-end face and the rotor undersurface a thrust bearing section is configured. Micro-gaps are formed continuing between the sleeve upper-end face and the rotor undersurface; the sleeve inner-circumferential surface and the shaft outer-circumferential surface; and the cover member inner face and the shaft end face, where an axial support section is established. Oil continuously fills the micro-gaps without interruption, configuring a fully filled hydrodynamic bearing structure. Hydrodynamic pressure-generating grooves in the radial bearing section are configured so that no axial flow is induced in the oil, and in the thrust bearing so that lift pressure, balanced by hydrostatic pressure in the axial support section, is imparted in the oil.

Spindle motor, and disk drive utilizing the spindle motor

The present invention may include acquiring a plurality of overlay metrology measurement signals from a plurality of metrology targets distributed across one or more fields of a wafer of a lot of wafers, determining a plurality of overlay estimates for each of the plurality of overlay metrology measurement signals using a plurality of overlay algorithms, generating a plurality of overlay estimate distributions, and generating a first plurality of quality metrics utilizing the generated plurality of overlay estimate distributions, wherein each quality metric corresponds with one overlay estimate distribution of the generated plurality of overlay estimate distributions, each quality metric a function of a width of a corresponding generated overlay estimate distribution, each quality metric further being a function of asymmetry present in an overlay metrology measurement signal from an associated metrology target.

Method and system for providing a quality metric for improved process control

The invention relates to a fluid dynamic bearing system that comprises at least one stationary part that has a shaft and two bearing plates disposed on the shaft at a mutual spacing, and at least one rotating part that is supported so as to rotate about a rotational axis with respect to the stationary part, and comprises a bearing bush and a sleeve enclosing the bearing bush. A bearing gap filled with bearing fluid is provided between the parts and at least one sealing gap for sealing the bearing gap that extends concentric to the rotational axis. The bearing comprises at least one fluid dynamic radial bearing and two fluid dynamic axial bearings and at least one recirculation channel that connects the two axial bearing regions to each other. According to the invention, the largest radial diameter of the recirculation channel is greater than or equal to the largest diameter of the sealing gap, and the smallest radial diameter of the recirculation channel is greater than or equal to the largest diameter of an adjacent bearing plate. Moreover, additional and effective deairing of the recirculation channel is effected by a venting device. To realize improved equilibrium of pressure in the bearing gap and improved retention of the bearing fluid, the sealing gaps can be inclined, at least in sections, at an angle α, β with respect to the rotational axis, wherein the angles may have different sizes.

Fluid dynamic bearing system

A disk rotating device includes a stationary shaft having one end fixed to a casing, a minor shaft having one end fixed to the casing, a flange member located on one end face of the stationary shaft and being in contact with a contact portion of the minor shaft, a rotary member rotatably mounted around the stationary shaft and supporting a disk, a thrust plate fixed in the vicinity of an end face of the rotary member and being in contact with the flange member, and a motor having a motor stator provided in the casing and a motor rotor provided in the rotary member so as to rotate the disk together with the rotary member around the stationary shaft. A radial bearing groove is provided on at least one of an outer circumferential surface of the stationary shaft and an inner circumferential surface of the sleeve. An outer thrust bearing groove is provided on a surface of at least one of the flange member and the thrust plate, at which the flange member and the thrust plate are in contact with each other. These grooves have lubricant retained therein.

Disk rotating device having dynamic-pressure fluid bearings

In this paper we discuss the technical issues of hydrodynamic bearings (HDB) for hard disk drives (HDD). We also report results of numerical analysis and of experiments aimed at solving the characteristic problems of high-speed HDDs.

Design of hydrodynamic bearings for high-speed HDD

A magnetic recording apparatus includes an arm, an airvane, a regulating member, and an urging member. The arm has a head slider including a magnetic head at a free end thereof, and is moved by an actuator device between a scan position and a stop position. The arm scans a surface of a disk for reading and/or writing information thereon at the scan position. The head slider is elastically supported on the arm by a flexure. The airvane is disposed adjacent to the disk, and is urged to a first position in opposition to a direction of air flow generated by rotation of the disk. The airvane moves in response to air flow generated by rotation of the disk to a second position in the direction of the air flow. The regulating member is provided at a position corresponding to the stop position of the arm and connected with the airvane. The regulating member moves between a regulating position for regulating vertical movement of the flexure by contacting the flexure and a non-regulating position for moving away from the flexure. The urging member urges the airvane to the first position so that the flexure is regulated by the regulating member when the disk is not rotating.

Magnetic recording apparatus with air vane actuated regulating member for head slider

In a hydrodynamic bearing device in which a radial bearing face having a dynamic pressure generating groove on a shaft or an inner periphery of a sleeve is provided and a clearance between the shaft and the sleeve is filled with lubricant, an annular depression is provided on one end face of the sleeve adjacent to a rotor hub and a cover plate for covering the depression is attached to the sleeve so as to define a reservoir for the lubricant or air for the purpose of preventing such a risk that absence of an oil film occurs in clearances of a bearing of the hydrodynamic bearing device due to outflow of oil upon forcing of the oil by air received into the bearing. A step portion is provided on the other end face of the sleeve such that the step portion and the reservoir are communicated with each other by a communication hole. During operation of the hydrodynamic bearing device, air in the hydrodynamic bearing device reaches the reservoir via the communication hole so as to be discharged from the reservoir.

Hydrodynamic bearing device and disk rotating apparatus

A hydrodynamic bearing device with high reliability, with which reductions in size, weight, and thickness can be achieved, as well as a motor and a disk driving apparatus that make use of this hydrodynamic bearing device. The hydrodynamic bearing device comprises a shaft, a thrust flange, a sleeve, a seal plate, and a retaining plate. A radial dynamic pressure bearing is formed in the radial direction gap between the shaft and the sleeve, and a thrust dynamic pressure bearing is formed in the thrust dynamic bearing gap between the sleeve and the thrust flange. A communicating hole is formed for communicating between the gap between the sleeve and the seal plate and the thrust direction gap between the sleeve and the thrust flange. The radial dynamic pressure bearing and/or the thrust dynamic pressure bearing are formed such that a lubricating oil circulates in the gap between the sleeve and the seal plate from the inner peripheral side of the sleeve toward the outer peripheral side.

Hiroaki Saito

Papers

Disk rotating device having dynamic-pressure fluid bearings

Design of hydrodynamic bearings for high-speed HDD

Magnetic recording apparatus with air vane actuated regulating member for head slider

Hydrodynamic bearing device and disk rotating apparatus

Hydrodynamic bearing device, motor, and disk driving apparatus