JPH047012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a servo track writer for a magnetic disk device. Currently, most of the positioning methods for magnetic heads in magnetic disk devices are servo surface servo methods. In the servo surface servo method, an error occurs in positioning accuracy due to the difference in temperature between the servo disk and the data disk. In particular, as the track density increases, the positioning error of the magnetic head increases, making it impossible to achieve a high areal density. Therefore, various data surface servo systems are being studied to improve positioning accuracy. Among the data surface servo methods, the buried servo method using a magnetic double layer disk is considered to have the highest accuracy. In order to realize a buried servo system using a magnetic double layer disk as a magnetic disk device, a servo track writer is required to record servo information for head positioning on a servo medium below the magnetic disk. In conventional servo track writers for servo surface servo systems, one disk in the head disk assembly is selected, in-disk information and reference clock information are recorded on that disk, and the recorded information is reproduced. The servo information of the odd and even tracks is recorded on the servo disk using the reference clock signal.

When applying this method to a head/disk assembly for data surface servo (buried servo) using a magnetic double layer disk, it is necessary to record servo information on all surfaces of the disk, so servo information must be recorded on each disk surface. The time is N times the number of disk surfaces compared to the servo recording time of a conventional servo track writer, which has the drawback of significantly increasing the cost of the magnetic double layer disk.

The purpose of the present invention is to improve these problems and
The purpose of the present invention is to provide a servo track lighter for buried servo.

A servo track writer for a magnetic disk device according to the present invention includes a magnetic head for a reference clock, a recording and reproducing circuit for the reference clock connected to the magnetic head, a magnetic head for an index, a recording and reproducing circuit for the index connected to the same, and a magnetic head for a reference clock and a recording and reproducing circuit for an index connected thereto. A servo track writer for a magnetic disk device having a servo track writer control section, a servo signal recording circuit, and a head positioning control section connected to the head disk assembly includes a single layer magnetic disk coupled to the same shaft as the head disk assembly, and a single layer magnetic disk disposed on the disk. The index reference clock mechanism consists of two reference clock heads, a selection circuit for the heads, and an index head, and the reference clock signal from the mechanism allows the entire magnetic field in the head disk assembly to be controlled. It is characterized by having a number of servo signal recording circuits corresponding to the number of surfaces of the magnetic double layer disk for simultaneously recording servo signals on the surface of the double layer disk.

Therefore, in order to record servo signals simultaneously on each disk surface, the time required to record servo information on a magnetic double layer disk is the same as the time required to record servo information on a conventional single layer disk for servo surface servo, and the magnetic The manufacturing cost of double layer discs is lower.

The features of the servo track writer for magnetic disk drives according to the present invention will be explained below using comparative examples and examples.

Comparative Example FIG. 1 is a block diagram of a conventional servo surface servo type servo track writer. In Figure 1,
The lower surface of disk 3 among the conventional single-layer magnetic disks 1 to 5 is the servo surface. In the servo surface servo method, head positioning on all other disk surfaces is performed using servo information on the lower surface of the magnetic disk 3. Therefore, a servo track writer is required to record servo information only on the lower surface of the magnetic disk 3, and a block diagram of the servo track writer is shown in FIG.

In FIG. 1, index information is first recorded by the head 9 on the lower surface of the disk 4 through the index recording circuit 16. The recorded index signal is reproduced by the head 9, amplified by the reproduction amplifier 17, and pulsed to be used as a reference signal. Using this index signal as a reference signal,
A reference clock signal is recorded on the upper surface of the disk 4 through the head 8 by a reference clock recording circuit 18. Then, the reference clock signal regenerated by the head 8 is amplified by the reference clock regenerative amplifier 19,
The signal is made into a pulse by the pulsing circuit 20 and used as a reference clock signal. Using this reference clock signal, servo signals for odd and even tracks are recorded on the servo surface (lower surface) of the disk 3 by the servo recording circuit 14 and the magnetic head 10. The positioning of the actuator 11 and the servo recording head 10 at this time is performed by a head positioning mechanism having a highly accurate distance measuring mechanism and a control section 15.

In the conventional servo track writer as described above, it is only necessary to record servo information on a single disk surface, so the reference clock and index clock signals are transmitted to other disks in the head disk assembly. Detection is possible using surfaces. However, in the case of a head disk assembly using a magnetic double layer disk, it is necessary to record servo information on all sides of the disk, but with a conventional servo track writer, the magnetic information used for the index and reference clocks must be recorded. Servo information will be recorded on each magnetic double layer disk surface other than the disk, and the servo information recording time will depend on the number of magnetic double layer disk surfaces N to be recorded.
This has the drawback of significantly increasing the cost of the magnetic double layer disk.

Embodiment FIG. 2 shows a configuration diagram of a servo track writer for a magnetic disk device according to the present invention. In FIG. 2, on top of an index/reference clock component 57 consisting of a single-layer magnetic disk 27, reference clock heads 29, 30, and an index head 40, there are arranged 22 to 26 discs.
A head disk assembly consisting of a magnetic double layer disk and magnetic heads 41 to 50 is set and connected to the same rotating shaft 28,
The reference clock heads 29 and 30 of the index reference clock mechanism regenerate low frequency reference clock signals for the even and odd tracks, respectively, and use the reference clock signals to regenerate the low frequency reference clock signals for the even and odd tracks. - Servo information is simultaneously recorded on each magnetic double layer disk surface of the disk assembly by a servo signal recording circuit and a servo signal recording magnetic head corresponding to each disk surface.

In this way, the servo information recording time by a servo track writer for a magnetic disk device using a magnetic double layer disk can be significantly shortened, and the manufacturing cost of the magnetic double layer disk can be reduced. When applying a conventional servo track writer for single-layer magnetic disk drives to a buried servo servo track writer for magnetic disk drives, servo signals are recorded on the magnetic double-layer disk other than the magnetic disk surface for index and reference clocks using magnetic Since the recording is repeated as many times as the number N of disk surfaces, the recording time becomes very long and the manufacturing cost of the magnetic double layer disk increases. By connecting the number of magnetic disks corresponding to the magnetic double layer disk surface and simultaneously recording servo information, the servo information recording time is shortened, and it takes the same time as recording servo information on one surface of the disk.

This embodiment will be specifically explained as follows.

In FIG. 2, an index signal and a reference clock signal (two low frequency signals) previously recorded on a single-layer magnetic disk 27 in an index/reference clock mechanism 57 connected to a rotary motor 7 are transmitted. Magnetic head 40,2
Play by 9,30. The reference clock signal is regenerated by the head 29 (or 30) selected by the head selection circuit 55, amplified by the reference clock regenerative amplifier 19, and the reference clock pulse is detected by the pulse generator 20. Servo track lighter control section 58
Servo signal recording circuits 59, 60, 61, 62, 63,
64, 65, 66, 67, 68, 69 at the same time, and the output current of each recording circuit is input to the corresponding magnetic heads 41, 42, 43, 44, 4, respectively.
5, 46, 47, 48, 49, and 50 simultaneously to record servo information on each disk surface of magnetic double layer disks 22 to 26. At this time, the positioning of the servo recording head is performed by a high precision head positioning mechanism and a control section 54.

As in this embodiment, by arranging servo signal recording circuits and servo recording magnetic heads in the number corresponding to each magnetic double layer disk surface and simultaneously recording servo information, it is possible to reduce the manufacturing cost of the double layer magnetic disk. This makes it possible to realize a servo track writer for a buried servo magnetic disk device.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are device configuration diagrams of a comparative example and an example, respectively. 1, 2, 3, 4, 5...single layer magnetic disk, 6
... Shaft, 7 ... Rotating motor, 8 ... Magnetic head for reference clock, 9 ... Magnetic head for index, 10 ... Servo information recording head, 11 ... Actuator, 13 ... Servo signal reproducing circuit, 14... Servo signal recording circuit, 15
...Head positioning mechanism and control circuit, 16...
Index recording circuit, 17... index reproducing circuit, 18... reference clock recording circuit, 19... reference clock reproducing circuit, 20... pulsing circuit, 21... servo track writer control section , 22, 23, 24, 25, 2
6... Magnetic double layer disk, 41, 42, 43,
44, 45, 46, 47, 48, 49, 50...
Servo signal recording head, 27... single-layer magnetic disk for index/reference clock,
28... Rotating shaft, 29... Head for reference clock (odd number), 30... Head for reference clock (even number), 40... Head for index, 51... Actuator, 54...
Head positioning control section, 55... Head selection circuit for reference clock, 58... Servo track writer control section, 57... Mechanism section for index reference clock, 56... Gate circuit, 59, 60, 61 ,62,63,64,6
5, 66, 67, 68, 69... Servo signal recording circuit.

Claims (1)

[Claims] 1. A reference clock magnetic head and a reference clock recording and reproducing circuit connected to it, an index magnetic head and an index recording and reproducing circuit connected to it, a servo track writer control unit and a servo to which these are connected. A servo track writer for a magnetic disk device having a signal recording circuit and a head positioning control section includes a single-layer magnetic disk coupled to the same shaft as a head disk assembly, and two reference clock heads disposed on the disk. The index reference clock mechanism consists of the head selection circuit and the index head, and the reference clock signal from the mechanism generates servo signals simultaneously on all magnetic double layer disk surfaces in the head disk assembly. A servo track writer for a magnetic disk device, comprising a number of servo signal recording circuits corresponding to the number of surfaces of the magnetic double layer disk to be recorded.