Abstract: For a magnetic disk apparatus for reading and writing information to a magnetic disk in the present invention, the recessed portion of the cover of the magnetic disk apparatus has a two-level structure; the space between the inner surface of the recessed portion, corresponding to the region of the magnetic disk surface which the actuator arm does not traverse, and the surface of the magnetic disk is made as narrow as possible. The air flow generated in that space by the rotation of the magnetic disk is thereby suppressed and as a result, magnetic disk resonance is suppressed. Also, the noise level is further suppressed by having two layers of damping plates attached to the outer surface of the cover.

Abstract: The arrangement for mounting a sparkplug of an internal combustion engine includes mounting the sparkplug so that all of the outside electrodes are arranged at an intake port side area and/or an exhaust port side area. Alternatively, in the case where at least one of the outside electrodes is located outside of the above-mentioned areas, no other remaining outside electrodes are arranged at a position that faces that outside electrode across the central electrode.

Abstract: A recording disk apparatus includes a recording disk supported by a rotation axis. A clamp is fixed at the tip end of the rotation axis by screws so as to urge the recording disk against a flange at the base end of the rotation axis. The screws are disposed along an imaginary circle concentric to the rotation axis so as to fix a plane body of the clamp at the tip end of the rotation axis. A rigidity reduction mechanism reduces rigidity of the plane body at an intermediate area relative to the screw bore areas, which intermediate area is defined between the screw bore areas along the imaginary circle. The rigidity reduction mechanism serves to suppress the undulation of the magnetic disk.

Abstract: A recording disk drive includes a shroud wall spaced from a peripheral end of the recording disk by a gap equal to or smaller than 0.5 mm. A rectification groove is formed in the shroud wall at a position adjacent an area opposed to the peripheral end of the recording disk. Reduction in gap between the peripheral end of the recording disk and the shroud wall serves to reduce the amplitude of the flutter to be induced in the rotating recording disk. Moreover, as the gap gets smaller, the flutter reduces at a higher rate in response to increase of the depth of the rectification groove. Specifically, if the gap between the peripheral end of the recording disk and the shroud wall is set equal to or smaller than 0.5 mm, the groove can be made shallower so as to still efficiently suppress the flutter of the rotating recording disk.

Abstract: A recording disk drive comprises a shroud wall spaced from an peripheral end of the recording disk by a gap equal to or smaller than 0.5 mm. A rectification groove is formed in the shroud wall at a position adjacent an area opposed to the peripheral end of the recording disk. Reduction in gap between the peripheral end of the recording disk and the shroud wall serves to reduce the amplitude of the flutter to be induced in the rotating recording disk. Moreover, as the gap gets smaller, the flutter reduces at a higher rate in response to increase of the depth of the rectification groove. Specifically, if the gap between the peripheral end of the recording disk and the shroud wall is set equal to or smaller than 0.5 mm, the groove can be made shallower so as to still efficiently suppress the flutter of the rotating recording disk.

Abstract: Disclosed herein is a magnetic disk drive including a spindle shaft fixed to a base, a coil mounted on the spindle shaft, a spindle hub rotatably mounted on the spindle shaft, a magnetic disk fixed to the spindle hub and having a plurality of tracks, a permanent magnet fixed to the spindle hub, a magnetic head for reading/writing information from/to the magnetic disk, and an actuator for moving the magnetic head across the tracks of the magnetic disk. The magnetic disk drive further includes a cover fixed to the base and having a hole at a position corresponding to the spindle shaft, a first metal washer placed on the cover at a portion around the hole, a second metal washer for sandwiching the cover at the portion around the hole in cooperation with the first metal washer, and a screw for securing the first and second metal washers to the spindle shaft.

Abstract: A rotational position detecting apparatus for an internal-combustion engine for use with a Hall IC comprising at least two Hall elements for detecting the protrusion of a rotator. One of the two Hall elements is arranged with a magnet for forming a magnetic field, and the magnet is disposed on one side of the Hall IC to form a magnetic circuit for converging the magnetic flux on only one element within the Hall IC.

Abstract: A recording disk apparatus comprises a recording disk supported by a rotation axis. A clamp is fixed at the tip end of the rotation axis by screws so as to urge the recording disk against a flange at the base end of the rotation axis. The screws are disposed along an imaginary circle concentric to the rotation axis so as to fix a plane body of the clamp at the tip end of the rotation axis. A rigidity reduction mechanism reduces rigidity of the plane body at an intermediate area relative to screw bore areas, which intermediate area defined between the screw bore areas along the imaginary circle. The rigidity reduction mechanism serves to suppress the undulation of the magnetic disk.

Abstract: The arrangement for mounting a sparkplug of an internal combustion engine in accordance with the present claimed invention is that the sparkplug is mounted so that all of the outside electrodes are arranged in areas of a side of an intake port opening and/or a side of an exhaust port opening limited by the sparkplug and the intake port opening and by the sparkplug and the exhaust port opening or in case at least one of the outside electrodes locates outside of the above-mentioned limited area, other remaining outside electrodes are arranged at positions to avoid facing the outside electrode locating outside of the limited area across the central electrode.

Abstract: A disk drive includes a casing for enclosing at least a disk and a head. Rectification walls are disposed at corners of the casing. The walls serve to rectify an air stream generated by rotation of the disk at the periphery of the rotating disk. A bypass is defined between the side wall of the casing and at least one rectification wall. A filter is disposed in the bypass for catching dust in the air stream. A parameter d/L, where d is the width of an entrance of the bypass and L is the length of the comer along the periphery of the disk, is determined so that vibration of the rotating disk is equal to or less than an admissible value estimated from a tracking error margin. The tracking error margin is estimated from a track pitch on the disk. Reliable positioning of the head with respect to the disk can be achieved with the present invention.