JPH0221045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a system for servoing a magnetic disk so that the head is precisely positioned on the track to read data records.

As shown in FIGS. 1 and 2, the conventional servo system for magnetic disks uses one of the recording surfaces 2 and 3 on both sides of the disk 1 as a servo surface, on which a servo signal 4 is previously recorded. There is a method in which the data signal 7 is read by the servo head 5 and the data signal 7 is written or read on the recording surface 3 while controlling the position of the read/write head 6, and a method in which the servo track is arranged side by side with the recording track even though it is on the same surface as the recording surface. Ta.

In these known methods, the entire surface of the disk cannot be effectively used for data recording, and since both recordings are performed at separate locations, the head position control mechanism requires precision or is complicated; There were fundamental drawbacks such as inaccurate and unstable positioning.

Furthermore, in order to make the head follow the track faithfully, it is known that the servo recording for calibrating the positioning of the track is performed on the same recording layer as the data recording layer, and the positions thereof overlap. In order to prevent recording and data recording from interfering with each other during reproduction and generating noise, the frequency of magnetization reversal in servo recording must be made much lower than that in data recording. A difficult problem was that the accuracy of calibration decreased, making it impossible to use with high-density recording disks.

The present invention overcomes the drawbacks of the prior art as described above. FIG. 3 shows the principle of the present invention, in which a servo signal 8 modulated only by FM or only by MFM on the magnetic disk 1 and a data signal 7 overlap in the vertical direction, and the servo signal 8 and the data signal 7 are overlapped in the vertical direction.
It's below. Specifically, as shown in FIG. 4, a servo signal 8 is first recorded on a disk 1 having a magnetic coating 10 formed on a polyester film 9 by a servo writing head 5 deep into the magnetic coating 8, as shown in FIG. It is shipped to the user in the same condition. The user writes or reads the data signal 7 from above the servo signal 8 using the read/write servo head 11 as shown in FIG. Therefore, as shown in the cross-sectional view of the disk 1 in FIG. 6, a portion 12 in which data recording is written and a portion 13 in which servo recording is written thereunder are formed within the magnetic coating 10.

FIG. 7 shows the read/write servo head 11 of the present invention, in which a servo head 5 made of thin film head technology is formed at the end of the slider 14, and a read/write head 6 is formed over this. 5 may be a read/write head, and 6 may be a servo head.
This thin film head formation technique is well known and will not be described in detail here. 15 is a suspension made of an elastic metal plate. Note that the present invention also includes a case where the servo head and the read/write head are separate.

Figure 8 is a view of the disk 1 seen from the cross-sectional direction, and when the disk 1 rotates in the 17 direction, the head moves relatively in the 18 direction, and the disk rotation speed increases.
At high speed rotation of 3600 RPM, the slider 14 flies over the disk 1. Substrate 1 of disk 1 made of polyester film, aluminum, etc.
A servo signal 8 is recorded in the lower part of the magnetic layer 10 formed on the magnetic layer 9, and a data signal 7 is recorded thereon.The servo head 5 on the slider 14 picks up the servo signal 8, The read/write head 6 on the servo track performs writing or reading. Since it is a known technique to pick up the servo signal and control the head so as to place it on the servo track, it will not be described in detail here.

To further explain the embodiment of the present invention, FIG. 9 shows that in the embodiment of the present invention, a signal 8 obtained by modulating the servo signal with FM or MFM with a low magnetization reversal density is recorded,
From above, for example, 20 kilohertz as shown in Figure 10.
When the data signal 7 to which an AC bias is applied is recorded, the servo signal 8 appears below the data signal 7 as shown in FIG. 11 when viewed from above the track.

FIG. 12 is also an embodiment of the present invention, in which the data signal 7 to which AC bias is applied is first recorded, and then the 13th data signal is recorded.
As shown in the figure, the FM or MFM modulated servo signal 8 is recorded from above, and when viewed from above the track, the first
As shown in FIG. 4, the servo signal 8 is recorded below the data signal 7.

In addition to the above, it is also possible to perform FM or MFM modulation on the servo signal and data signal at different frequencies and overlap them.

FIG. 15 shows a cross section of a medium in another embodiment of the present invention, in which a servo signal 8 is recorded by a magnetic field perpendicular to the surface of the medium by a head 5, and then as shown in the cross section of the medium in FIG. The head 6 horizontally moves the data signal 7 from above the vertical magnetic field servo signal 8 in FIG.
Write.

FIG. 17 is a top view of this, with servo recording below the data recording.

For example, in the earlier application, JP-A No. 56-83806,
A servo signal is provided below the data signal of the magnetic recording medium, and this servo signal has phase modulation as an identifier in some places. In contrast, in the present invention, the servo signal below the data signal is only FM,
or MFM only, in which the servo signal is recorded entirely at a lower frequency than the data signal frequency, so this servo signal can be clearly separated from the data signal, and all servo signals are packed in a high density. Therefore, there is a great effect that the data signal can be recorded at a higher density and reproduced with higher fidelity than that of the prior application.

The present invention includes both soft floppy disks and hard rigid disks.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a conventionally known magnetic disk servo system. FIG. 2 is a side view of FIG. 1. FIG. 3 is a side view showing the principle of the present invention. FIG. 4 is a side sectional view of the magnetic disk. FIG. 5 is a side sectional view of a magnetic disk on which servo signals are recorded. FIG. 6 is a side sectional view showing an embodiment of the present invention in which a data signal is read or written from the disk of FIG. 5 by a magnetic head. FIG. 7 is a bottom view of the read/write servo head, and FIG. 8 is a side sectional view showing an embodiment of the present invention. 9th
The figure shows servo recording, FIG. 10 shows data recording, and FIG. 11 is a plan view of the embodiment of the present invention, in which these are superimposed. FIG. 12 is a plan view of the embodiment of the present invention, and FIG. 13 is a plan view of the embodiment of the present invention, which shows data recording and FIG. 14 which shows servo recording. FIG. 15 is a side cross-sectional view for performing servo recording, and FIG. 16 is a side cross-sectional view for performing data recording. 7...Data signal, 8...Servo signal, 10...
...magnetic coating.

Claims (1)

[Claims] 1. A servo characterized in that servo recording is provided below data recording on the same track, the servo recording is only FM or only MFM, and all servo signals are recorded at a frequency lower than the data signal frequency. disk system.