Abstract: A method for manufacturing a langasite single crystal substrate comprises the steps of polishing at least one of the main surfaces of a raw material substrate; and wet-etching said polished main surface of the substrate with a solution including H3PO4, HNO3 and CH3COOH.

Abstract: In order to allow lubricant to move from the outside into the inside of a thrust bearing easily, an escape is provided in a base and a circumferential recess in a plate. As a result, a hub with magnetic disks mounted thereon can rapidly float up in a correct position at start-up of rotation thereby to perform correct recording and reproduction of information.

Abstract: A spindle motor unit having a hydrodynamic bearing that retains a necessary amount of lubricant in the thrust bearing even when rotating and stopping operations are frequently repeated, and ensures reliability of the bearing, and allows correct recording and reproducing operations is obtained by reducing the clearance formed between the inner diameter surfaces 11d and 11e of base 11 and the outer diameter surface of flange 13.

Abstract: In order to not only obtain excellent sound quality in a long-time recording mode not less than five times a standard recording mode by preventing, without narrowing a track pitch of a high-fidelity head, the high-fidelity head from tracing the third sound track from a target sound track as well as excellent picture quality free from crosstalk from an adjoining video track of a target video track but enable special playback without using a field memory in a video tape recorder, one head pair in conventional double azimuth type four heads for the standard recording mode and a threefold recording mode is used for video recording in the long-time recording mode and a head pair having a head width smaller than a width of a recording track is used exclusively for video playback in the long-time recording mode.

Abstract: A method for manufacturing a langasite single crystal substrate comprises the steps of polishing at least one of the main surfaces of a raw material substrate; and wet-etching said polished main surface of the substrate with a solution including H3PO4, HNO3 and CH3COOH.

Abstract: A hydrodynamic bearing spindle motor comprising: a fixed member which has a radial bearing portion; a rotational member; a rotary shaft which is rotatably supported by the radial bearing portion of the fixed member and is secured to a substantially central location of the rotational member so as to extend in a vertical direction of the hydrodynamic bearing spindle motor such that the rotational member is disposed above the fixed member; lubricant which is provided between the radial bearing portion of the fixed member and the rotary shaft; a projection which is provided on a lower face of the rotational member so as to be disposed radially outwardly of the rotary shaft and has an oblique inner periphery expanding gradually radially outwardly towards a distal end of the projection; a lubricant receiving member which is secured to an upper face of the fixed member so as to be disposed radially outwardly of the projection; and oil repellent for repelling the lubricant, which is applied to the projection and its