Abstract: A drum motor for a VCR includes radial and thrust hydrodynamic bearings that are composed of a rotor-side bearing member formed by bringing a pair of first and second thrust plates into direct contact with both end surfaces of a radial bearing element and integrating them into one unit, and a stator-side bearing member in the form of a radial sleeve the inner peripheral surface and both end surfaces of which respectively cooperate with the outer peripheral surface of the radial bearing element and the mutually facing surfaces of the first and second thrust plates. A rotor magnet is secured to a rotating shaft. A motor casing is secured to the outer peripheral surface of the radial sleeve. A stator unit is secured to the motor casing. A dynamic pressure generating groove is provided on either each end surface of the radial sleeve or each of the mutually facing surfaces of the first and second thrust plates.

Abstract: A hydrodynamic bearing includes first and second thrust plates held against respective axially opposite ends of a cylindrical radial bearing member, and a cylindrical radial sleeve provided concentrically with the cylindrical radial bearing. The outer circumferential surface of the cylindrical radial bearing member and the inner circumferential surface of the cylindrical radial sleeve serve as sliding surfaces jointly making up a radial hydrodynamic bearing assembly, and the confronting surfaces of the first and second thrust plates and the end surfaces of the cylindrical radial sleeve serve as sliding surfaces jointly making up a thrust hydrodynamic bearing assembly. At least one of the sliding surfaces of the thrust hydrodynamic bearing assembly has grooves formed therein for generating a hydrodynamic pressure. At least one of the sliding surfaces of the radial hydrodynamic bearing assembly is coated with a uniform hydrogenated amorphous carbon film.

Abstract: A dynamic pressure bearing is provided with a moving side bearing member and a fixed side bearing member so as to support a rotor for rotation by generating a fluid dynamic pressure between the moving side bearing member and the fixed side bearing member. The dynamic pressure bearing includes a high-frequency exciting device for applying a high-frequency vibration to the fixed side bearing member at the time of at least one of start-up and shutdown of the rotor. In this way, both bearing members are kept almost free from contact with each other and a frictional resistance at start-up and/or shutdown is minimized.

Abstract: A hydrodynamic bearing for a spindle motor used in an environment of high degree of cleanness. A sliding surface of the hydrodynamic bearing is formed of a ceramic material with a surface roughness Ra not larger than 0.3 microns, and this sliding surface is coated thinly with at least one lubricant selected from among perfluoropolyethers having a functional group reactive with the ceramic material, thereby providing on the sliding surface a uniform thin film with a thickness in the range of from 20 to 100 angstrom and having protecting and lubricating functions. The lubricant is selected from among hydroxyl group-containing perfluoropolyethers, carboxyl group-containing perfluoropolyethers, and ester group-containing. The lubricant contains an antistatic agent.

Abstract: A ceramic hydrodynamic bearing used as a radial or a thrust bearing in a spindle motor for a hard disk driver. The bearing includes a ceramic bearing base having hydrodynamic pressure generating grooves. A sliding surface of the bearing base is irradiated with an energy beam with a high energy density to remove said material, thereby forming hydrodynamic pressure generating groove, and at the same time the grooves are coated with a modification layer that is formed by melting the ceramic material that constitutes said ceramic bearing base with the energy beam and by solidifying said ceramic bearing base.

Abstract: A single-phase brushless motor which can be manufactured at low cost and which can be started at any rotary position. The motor includes a rotary magnet having a plurality of magnetic poles and a stator armature having a plurality of poles, each of which is wound with a coil carrying a driving current. Each of the poles is divided circumferentially into at least two sectors, the cross sections of which at points where the magnetic flux density is a maximum being different from one another. A single position detector detects the rotary position of the rotary magnet relative to the stator armature, and the driving currents in each of the coils are controlled in accordance with the output of the position detector. In preferred embodiments, the poles have links which join them to a generally cylindrical central core. Holes are formed in at least some of the sectors of each of the poles, having different diameters.