Abstract: A method and apparatus for simply detecting the magnetic head position over a wide range. A magnetic disk has recorded thereon a plurality of data tracks 54 formed along the radial direction (arrow B), and burst pattern rows A, B, C, and D. Signal recording areas 50a and 50b of pattern rows A and B are arranged in a staggered manner, their end sides along the radial direction corresponding to respective widthwise central portions of tracks 54. Signal recording areas 50c and 50d of pattern rows C and D are also arranged in a staggered manner, their end sides along the radial direction corresponding to respective boundaries of tracks 54. Based on signals A, B, C, and D obtained by moving the magnetic head and reading each pattern row, data SA representing signal A/(A+B) and data SC representing signal C/(C+D) are generated.

Abstract: The optical fibers are arranged in a V groove formed at the surface of a silicon substrate and a cover is provided thereon. An electrode for solder bump is respectively formed at the position opposed with each other to the substrate and cover. These substrate and cover are deposited with solder in order to fix the optical fibers. The substrate or cover is previously provided, at the end point part of the optical fibers, with the mark for the positioning in the longitudinal direction of the optical fibers. The optical fibers are positioned with this mark. Here, the side surface of the optical fibers is provided with the metallized area at the position located in the predetermined distance from the end point thereof. Before fixing with the cover, the optical fibers can be deposited automatically to the predetermined position without alignment due to the self-alignment effect between the mark and metallized area.

Abstract: A disk drive apparatus and read error recovery method in a disk drive apparatus removes thermal asperities on disk surfaces. A projection, such as a thermal asperity, on the recording surfaces of disks is detected when a signal transducer contacts the projection. The flying height of the signal transducer is lowered, e.g., by reducing the disk rotation speed from the normal rotation speed in read/write operations, while the signal transducer is positioned over the detected projection on the track. The signal transducer strikes the projection to break the projection. This avoids a subsequent error from being caused by the thermal asperity.

Abstract: In an idle state, servo information from all sectors is not used, but the servo information from every other sector or from every three or more sectors is used so that head positioning can be performed with only a minimum amount of servo information. The power to the electric circuitry of a write or read system and a servo system, which is not needed in the idle state, is interrupted, from the arrival of the selected servo information to the arrival of the next selected servo information, by a power control signal generated in accordance with the timing of the sectors. The power consumption can be reduced by the amount corresponding to turning off the circuitry not needed, plus the amount needed for computing for position control.