Abstract: A motor having a fluid dynamic bearing generating a fluid dynamic pressure by forming an oil gap between a rotor and a stator such that oil is accommodated in the oil gap, and a first and second air dynamic bearing generating an air dynamic pressure by forming an air gap between the rotor and the stator such that air is introduced into the air gap. The fluid dynamic bearing generates a fluid dynamic pressure by forming an oil gap between an axial hole of a sleeve and a shaft such that oil is accommodated in the oil gap, and the first and second air dynamic bearings generate an air dynamic pressure by forming an air gap between an inner circumferential surface of a hub and an outer circumferential surface of the sleeve and between the inner circumferential surface of the hub and an upper plane surface of the sleeve, respectively.

Abstract: Disclosed is an aerodynamic bearing assembly for a spindle motor for hard disk drives, in which a hub of the spindle motor is pivoted in both radial and thrust directions by the ball bearing, which directly contacts the center of the hub, to perform rotation according to the rotational principle of a whirligig, and is subject to the thrust load through the aerodynamic bearing assembly with air groove(s) without being in contact with it, so that the hub maintains a rotational center without mechanical contact resulting in noise and starting failure of the assembly during an initial starting (low-speed rotation). The assembly includes air grooves, the air groove generating aerodynamic pressure between the hub and the aerodynamic bearing while the hub rotates.

Abstract: In a hydrodynamic bearing motor which rotatably supports a rotor by forming a hydrodynamic bearing by forming an oil gap between the rotor and a stator, the stator includes a base and a hollow sleeve fixedly coupled to the central portion of the base and having a flange formed at an upper end portion of the sleeve. The rotor includes a shaft forming journal bearings by forming an oil gap in the hollow of the sleeve and rotatably coupled to the hollow of the sleeve 120, a hub having the central portion to which an upper end portion of the shaft is fixedly coupled, having a cylindrical wall extending downward toward the outside of the flange from a lower surface of the hub, and forming an oil gap with an upper surface of the flange, thus forming an upper thrust bearing, and a thrust plate fixedly coupled to an inner circumferential surface of the cylindrical wall and forming a lower thrust bearing with a lower surface of the flange.

Abstract: Provided is a motor, which can minimize friction caused during initial operation and smoothly discharge static electricity generated during operation by employing both an air dynamic bearing and a fluid dynamic bearing using oil of predetermined viscosity. Bearing means employed in the motor includes a fluid dynamic bearing generating a fluid dynamic pressure by forming an oil gap between a rotor and a stator such that oil is accommodated in the oil gap, and an air dynamic bearing generating an air dynamic pressure by forming an air gap between the rotor and the stator such that air is introduced into the air gap. Specifically, the fluid dynamic bearing generates a fluid dynamic pressure by forming an oil gap between an axial hole of a sleeve and a shaft such that oil is accommodated in the oil gap, and the air dynamic bearing generates an air dynamic pressure by forming an air gap between an inner circumferential surface of a hub and an outer circumferential surface of the sleeve.

Abstract: Provided is a fluid dynamic bearing motor in which a rotor is rotatably supported by forming an oil gap between the rotor and a stator to form a fluid dynamic pressure bearing and a plurality of oil grooves are formed in a surface of the rotor or stator forming the oil gap and facing each other. The oil grooves include a first oil groove inclined at a first angle with respect to a circumferential direction, and a second oil groove extending from an end portion of the first oil groove and inclined at a second angle with respect to the circumferential direction. The first angle is formed relatively greater than the second angle.

Abstract: Disclosed is a spindle motor for hard disk drives capable of generating mechanical and electrical preloads to form a predetermined sized air gap through use of mechanical and electrical offsets, so that the spindle motor is prevented from being damaged by friction and heat generated during an initial starting. The spindle motor with mechanical and electrical offsets is designed so that a midpoint of the vertical width of the poles wound around by a coil of a stator is placed within a magnetic field so as not to be flush with a midpoint of the vertical width of a permanent magnet fitted on the inner circumferential surface of the hub, and each of the poles has at least one of its upper and lower end extending in a vertical direction by a predetermined length to distribute magnetic flux density differently between the upper and lower ends of each pole.

Abstract: Disclosed is a multiphase brushless DC motor of a concentrated winding type having shunt connection, and a control circuit. The brushless DC motor includes a rotor made up of a permanent magnet with M number of poles, and a stator operating in K number of phases by means of windings wound on N number of teeth, wherein the plurality of windings having the same excitation phases wound on the teeth, are each maintained in shunt connection so as to improve driving torque and a rotational speed. A brushless DC motor includes a switching section having a plurality of upper switching devices and a plurality of lower switching devices connected with each other in series. Each of the windings is connected between a common joint between the upper and lower switching devices, and a common joint between a lower power supply voltage and a plurality of upper power supply voltages.