Abstract: A spindle motor includes a rotary unit, a bearing mechanism, a stator, a base member, and a connector connected to a leader line extending from the stator through a communication hole of the base member. The connector includes a pedestal and a metal pin. The leader line is connected to a first pin terminal of the metal pin on a hole-positioning lower surface of a hole-defining portion of the pedestal. An upper surface of the metal pin is separated from the pedestal at a specified separation position between the first pin terminal and a second pin terminal. A connection position of the first pin terminal and the leader line on the hole-positioning lower surface is covered with an adhesive agent. The periphery of a gap between the metal pin and the pedestal over an extent from the first pin terminal to the separation position is sealed by the adhesive agent.

Abstract: In a spindle motor, a capillary seal portion having a radial dimension that decreases in an axially downward direction, and a labyrinth seal portion arranged above the capillary seal portion are defined between an outer circumferential surface of a rotating member and an inner circumferential surface of a tubular portion. The capillary seal portion includes a liquid surface of a lubricating oil positioned therewithin. The radial dimension of the labyrinth seal portion is smaller than the radial dimension of an upper end portion of the capillary seal portion, so that the labyrinth seal portion contributes to reducing evaporation of the lubricating oil.

Abstract: A fluid dynamic bearing apparatus includes a first minute gap, a second minute gap, a third minute gap, a fourth minute gap, and a fifth minute gap. A flow of a lubricating oil from the fifth minute gap to the fourth minute gap is caused by a plurality of dynamic pressure generating grooves arranged within the fluid dynamic bearing apparatus. This flow causes air bubbles mixed in the lubricating oil within the fifth minute gap to flow toward the third minute gap and be discharged to an outside through the third minute gap. In addition, a flow of the lubricating oil into the third minute gap caused by a centrifugal force accompanying rotation is inhibited.

Abstract: A rotor unit includes a substantially circular plate shaped cover portion, a rotor hub including a lower cylinder portion, and a magnetic field generating member attached on the lower cylinder portion. An annular salient portion is provided on the lower surface of the cover portion 31. The annular salient portion lies radial inwards of the lower opening of the through-hole of the cover portion and protrudes downwards in the shape of a ring whose center coincides with the central axis. The magnetic field generating member includes a rotor magnet and a back iron covering the outer surface and upper surface of the rotor magnet. When the magnetic field generating member is mounted to the rotor hub, the upper portion of the back iron comes in contact with the annular salient portion, which determines the axial position of the magnetic field generating member.

Abstract: A bearing mechanism includes a shaft, a sleeve portion, a thrust portion, and a cover portion. Lubricating oil is arranged in a communicating channel in the sleeve portion, a thrust gap between the sleeve portion and the thrust portion, and a tapered gap between an outside surface of the thrust portion and the cover portion. A lower end opening of the communicating channel is defined in an outer circumferential portion of a lower surface of the sleeve portion radially outward of the thrust gap. A radially outermost portion of the thrust portion is arranged either tangent to a wall surface of the communicating channel or closer to a central axis than the wall surface. The tapered gap is arranged closer to the central axis than a radially outermost point of the wall surface. The outer circumferential portion and the cover portion define a guide gap therebetween.

Abstract: A sleeve and a hub are fixed to each other, and then the sleeve and the hub are gripped and rotated around a central axis, during which cutting is performed over the inner peripheral surface of the sleeve and a flange surface of the hub. Thus, the flange surface can be finished accurately such that the flange surface is normal to the central axis and the inner peripheral surface of the sleeve.

Abstract: A spindle motor includes a rotor magnet including a plurality of pairs of magnetic poles polarized in a radial direction and arranged along a circumferential direction of the rotor magnet and a rotor hub supporting the rotor magnet and being rotatable around an axis of the circular shape of the rotor magnet. A circular surface in the form of a convex portion is provided on a magnetic shield portion of the rotor hub and is arranged to oppose one axial end surface of the rotor magnet and abut against the rotor magnet such that a gap is provided between the axial end surface of the rotor magnet and the circular surface of rotor hub.

Abstract: A method of measuring the counter-electromotive force of the motor accurately is disclosed. The counter-electromotive force of the motor changes with the rotational position and the rotational speed. The value of the counter-electromotive force measured during the inertial rotation is a value associated the simultaneous change of the rotational position and the rotational speed and required to be corrected. The change rate of the rotational speed is set as a deceleration function, and the data are statistically processed using the measurement value of the counter-electromotive force at minuscule time intervals. In this way, the error elements are eliminated for each motor measured thereby to determine the corrected counter-electromotive force at a predetermined rotational speed. Even a miniature motor rapidly decreased in speed can be accurately measured within a short time.

Abstract: A rotor hub includes a shaft connecting portion arranged to be connected to a shaft serving as a central axis, a disk loading portion centered about the central axis and arranged to support a disk shaped storage medium mounted thereon, a yoke arranged below the disk loading portion and supporting a field magnet at one of an inner side surface thereof and an outer side surface thereof, and a flexible portion connecting the disk loading portion to the yoke and being flexible with respect to a force applied thereto from the yoke.

Abstract: A method of measuring the counter-electromotive force of the motor accurately is disclosed. The counter-electromotive force of the motor changes with the rotational position and the rotational speed. The value of the counter-electromotive force measured during the inertial rotation is a value associated the simultaneous change of the rotational position and the rotational speed and required to be corrected. The change rate of the rotational speed is set as a deceleration function, and the data are statistically processed using the measurement value of the counter-electromotive force at minuscule time intervals. In this way, the error elements are eliminated for each motor measured thereby to determine the corrected counter-electromotive force at a predetermined rotational speed. Even a miniature motor rapidly decreased in speed can be accurately measured within a short time.

Abstract: A radial gap is formed between an outer circumferential surface of a shaft and an inner circumferential surface of a sleeve. The outer circumferential surface of the shaft and the inner circumferential surface of the sleeve radially face each other. Within the radial gap, a radial dynamic bearing portion including a groove row of dynamic pressure generating grooves each of which are circumferentially arranged so as to form a herringbone shape is formed. At axially upper and bottom portions of the groove row, upper and bottom planar circumferential portions are formed respectively. Axial width of the upper planar circumferential portion is wider than axial width of the bottom planar circumferential portion.

Abstract: A spindle motor includes a rotor magnet including a plurality of pairs of magnetic poles polarized in a radial direction and arranged along a circumferential direction of the rotor magnet and a rotor hub supporting the rotor magnet and being rotatable around an axis of the circular shape of the rotor magnet. A circular surface in the form of a convex portion is provided on a magnetic shield portion of the rotor hub and is arranged to oppose one axial end surface of the rotor magnet and abut against the rotor magnet such that a gap is provided between the axial end surface of the rotor magnet and the circular surface of rotor hub.