Abstract: An index pulse generating system utilizes two periodic motor speed signals, one generated by a speed sensor coil actuated upon by a permanent magnet rotor mounted to a turntable, and the other generated by one of magnetoelectric converters acted upon by another permanent magnet rotor mounted to the turntable as a part of a disk drive motor. The two motor speed signals are translated respectively into two series of discrete motor speed pulses. One of the two series of motor speed pulses are produced at rates of two different predetermined numbers per complete revolution of the turntable. The two predetermined numbers have no common measure so that an AND gate or the like inputting the two series of motor speed pulses puts out at least one pulse during each turntable revolution, with the output pulse being representative of a specific angular position of the turntable.

Abstract: An index pulse generating system utilizes two periodic motor speed signals, one generated by a speed sensor coil actuated upon by a permanent magnet rotor mounted to a turntable, and the other generated by one of magnetoelectric converters acted upon by another permanent magnet rotor mounted to the turntable as a part of a disk drive motor. The two motor speed signals are translated respectively into two series of discrete motor speed pulses. One of the two series of motor speed pulses are produced at rates of two different predetermined numbers per complete revolution of the turntable. The two predetermined numbers have no common measure so that an AND gate or the like inputting the two series of motor speed pulses puts out at least one pulse during each turntable revolution, with the output pulse being representative of a specific angular position of the turntable.

Abstract: A head carriage apparatus includes a head carriage including a head being placed onto a disk for recording and reproducing information on the disk and having an extension and a connecting portion formed on the extension integrally with the head carriage, a lead-screw shaft having a lead screw in which a thread ridge and a thread groove are formed, the connecting portion being fitted in the thread groove of the lead screw, a drive part for driving and rotating the lead-screw shaft so that the head carriage is moved in a radial direction of the disk parallel to an axial direction of the lead-screw shaft, a guide shaft for guiding movement of the head carriage in a direction parallel to the radial direction of the disk, the head carriage being supported by the guide shaft at two supporting positions being located apart from each other in axial direction of the guide shaft, and a resilient part for pressing the lead-screw shaft in a direction facing the head carriage, the resilient part being fixed at one end ont

Abstract: A thrust ball-bearing in which a good lubrication is maintained for a long period of time and having a long service life. The bearing comprises a plurality of balls having a uniform diameter, a retainer which retains the balls, and two plates situated at either side of the retainer and rotatable relative to each other via the balls. The retainer has a thickness less than the diameter of the ball. A plurality of holes that retain each ball is provided on the retainer and a groove having a rectangular cross section is formed in a portion between two adjacent holes. An amount of grease applied to the ball is collected inside the groove and provided to the ball located on the downstream side of flowing grease without moving outwardly of the groove even if a centrifugal force generated by a rotation of the bearing is exerted.

Abstract: A motor positioning method includes steps of: providing a frame of a disk drive apparatus having locating holes spaced apart from each other, the locating holes being located in accordance with a predetermined positional relationship between the locating holes and a target position; placing a positioning jig on a base surface, the positioning jig having a first connecting portion with a diameter corresponding to a reference opening at the target position and second connecting portions with diameters corresponding to respective ones of the locating holes, the second connecting portions and the first connecting portion being located in accordance with the positional relationship; placing the frame onto the positioning jig so that the second connecting portions are fitted into the locating holes; and placing a board having a drive motor, a shaft and the reference opening at the target position, onto the frame attached to the jig so that the first connecting portion is fitted into the reference opening, thus posi