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| Buffered asynchronous communications element with receive/transmit control and status reporting |
| OF THE PREFERRED EMBODIMENT FIG. 1 shows a data communications device, Asynchronous Communications ... |
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| Compact disk read only memory recording system with speed control |
| OF THE PREFERRED EMBODIMENT The Circuit FIG. 1 schematically shows an apparatus for producing a ... |
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| Electronic timepiece |
| OF THE PREFERRED EMBODIMENTS Hereinafter is explained in detail this invention according to the ... |
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| Device for detecting traveling speed of pickup |
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| Optical pickup actuator for an optical disc player having a plurality of tracking coils |
| Therefore, it is an object of the present invention to provide an optical pickup actuator for an ... |
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High speed seek sector servo magnetic disk drive unit
| Details |
Inventors: Tsuyoshi, Toshiaki; Seo, Yosuke; Aoi, Hajime;
Assignee: Hitachi, Ltd. (Tokyo, JP)
Primary Examiner: Psitos; Aristotelis
Assistant Examiner: Robertson; David L.
Attorney, Agent or Firm: Antonelli, Terry, Stout & Kraus
A disk drive unit is disclosed, which comprises a recording medium having more than two disk-shaped recording faces disposed on each other with an interval; information tracks disposed along the periphery on the more than two recording faces and servo signal fields on the recording faces, in the peripheral direction for different recording faces; more than two heads reading out servo information from the servo signal fields on the more than two recording faces; head moving means for moving the heads in the radial direction of the recording faces, linked with each other; means for obtaining position signals on the recording faces at different points of time for different heads on the basis of the servo signals; means for obtaining information on the relative velocity of the heads to the recording faces from the position signals at different points of time for different recording faces, and control means for effecting the velocity control by means of the head moving means on the basis of the information on the relative velocity. |
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DETAILED DESCRIPTION The object of the present invention is to provide a disk drive unit capable of detecting the position and the velocity of the head with a high precision in a sector servo type magnetic disk drive unit and as a result realizing a high velocity access by the embedded servo method.
In order to achieve the above object, a first feature of the present invention is that the information is arranged on a plurality of faces on a same spindle, shifted from each other in the peripheral direction, so that the effective sampling frequency at the access is increased and the velocity detection is effected with a short time lag and a high precision and at the same time the position detection can be effected frequently by sampling sequentially the servo information on this plurality of faces.
Further, in above method, since corresponding points on different faces are slightly different in the position in the radial direction because of variations in the course of time, even if they belong to a same cylinder, when the velocity information is calculated, starting from the position information from the plurality of faces, velocity errors can be produced.
As a measure for solving this problem, the velocity detection is effected by using the position information coming from a same surface and different sets of the velocity information on the plurality of faces shifted from each other are connected with each other to raise an equivalent sampling frequency of the velocity signal.
Another form of realization, the offset amount between different faces is measured for every head at the track following mode and stored in a predetermined memory and a more precise position of the head can be obtained by compensating the position information of the head by means of the values stored in the memory.
On the other hand a second feature of the present invention is that the velocity is obtained by extrapolation by calculation or by using the driving current for the voice coil motor (hereinbelow abbreviated to VCM) in order to reduce influences of the time lag on the velocity information obtained by calculation, starting from intermittent position information obtained from the face of the disk
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