Abstract: The position of an optical pickup with respect to a disk is maintained accurately by preventing the free end portion of a cantilever movable member from being displaced lower than its proper position during the rotation of the disk even if the movable member is heavy to have improved vibration characteristics. There are provided a movable member 4, a chassis 1, a clamp mechanism 3, and a cam mechanism 5. The cam mechanism 5 includes a shift lever 51 connected to the free end portion of the movable member 4 via elastic bodies 42 and a cam main body 55. Positioning means 8 is composed of a protrusion 53 on the shift lever 51, a stepped engaging surface 15 for supporting the protrusion 53 thereon, and a guide mechanism 71. There is also provided anti-positioning means 9 for disengaging the protrusion 53 from the engaging surface 15.

Abstract: An optical head apparatus comprises a head unit for irradiating an optical disk with a light beam for recording or reproducing data, a holder for fixing the head unit thereto, a support unit for movably supporting the holder in a radial direction of the optical disk, a support member fixed to the holder, a rack unit movably engageable with the support member within a predetermined range and having a rack along a moving direction of the holder, a gear meshing with the rack of the rack unit, so as to transmit rotating force of a drive source to the rack, and an urging unit for urging the rack unit against the support member in such a manner that the rack meshes with the gear by a predetermined resilient force.

Abstract: In a disc cartridge, the shutter opening/closing operation is to be performed reliably. To this end, the distal ends of a first engagement member 75 and a second engagement member 79 provided to a base 66 are pivotally movable in a direction along a lateral surface of a housing 51, in addition to being movable in a direction perpendicular to the lateral surface of the housing 51. The state of engagement of the first engagement member 75 and the second engagement member 79, provided to the base, with a first mating engagement section 110 and with a second mating engagement section 108, provided to an inner rotor 101, facing outwards from one lateral surface of the housing 51, when the base 66 performs relative movement along the lateral surface of the housing 51, may be maintained for prolonged time, while the load applied to the distal ends during engagement and disengagement may be reduced.

Abstract: A disk drive unit is provided that is capable of reasonably, smoothly opening/closing a shutter by rotation of an inner rotor. The disk drive unit is configured such that an inner rotor (4) is reasonably, smoothly rotated by sequentially engaging a shutter opening/closing starting projection (72), a rack portion (74), and a shutter opening/closing ending projection (76) of a rack member (71) with a shutter opening/closing starting recess (26), a partial gear (27), and a shutter opening/closing ending recess (28) in the outer periphery of the inner rotor (4).