JPH0581690A - Disk device - Google Patents

Abstract

PURPOSE:To provide a device which has a smaller tracking error and avoids a reduction in RF signal output levels. CONSTITUTION:An RF level detector 9 detects the RF level obtained from clock pits so that the level becomes a maximum when an offset is added by an offset adder 8. While the above operation is being conducted, the angles of radial direction of the head of an optical system 3 and a magneto-optical disk 1 are adjusted by a skew controlling circuit 10 so as to make the tracking error signals zero which are detected by a tracking error detector 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device for removing a radial skew by adjusting an inclination angle of a head with respect to a radial direction of a disk.

[0002]

2. Description of the Related Art In a magneto-optical disk device, the entire surface of the disk is accessed by gradually moving a head in the radial direction. In this case, unless the head and the disk surface are parallel to each other, the beam spot for irradiating the head surface does not become a perfect circle, which causes various problems.

[0003]

For example, if the parallelism of the head with respect to the radial direction of the disk is poor, radial skew occurs and the point where the tracking error becomes zero does not match the actual on-track state. However, since it is necessary to minimize the tracking error in order to perform tracking, conventionally, it is necessary to allow the output level of the RF signal to decrease and adjust the tracking servo to a point where the tracking error becomes zero. Had a problem.

The present invention has been made in view of such a situation, and an object thereof is to provide a device which makes a tracking error zero and does not cause a decrease in the output level of an RF signal.

[0005]

In order to solve such a problem, the present invention provides an RF level detecting section 9 as a level detecting means for detecting a reproduction RF signal level from a magneto-optical disk 1 as a disk, for example. , An offset adder 8 as an offset adding means for adding an offset to the tracking servo system to adjust the level detected by the RF level detection unit 9 to the maximum, and a tracking error when the offset is added is minimized. A skew control circuit 10 is provided as a skew control means for controlling the radial skew.

[0006]

The center of the track is traced by maximizing the output level obtained from the disc when the offset is added. Since the offset at this time is caused by the radial skew, if the skew control circuit 10 controls so as to minimize the tracking error, the radial skew is removed,
You will be tracking the center of the track.

[0007]

1 is a block diagram showing the configuration of an embodiment of a disk device to which the present invention is applied. As shown in FIG.
Is rotated by a motor 2, and the information recorded therein can be read by an optical system 3 including an optical head and a magnetic head. The magneto-optical disk 1 has a data section in which magneto-optically modulated data is recorded, following a servo section in which servo pre-pits are recorded. An RF signal based on the pre-pits is reproduced from the servo section. The MO signal is reproduced. In the apparatus of FIG. 1, the RF signal from the servo section is detected by the RF signal detector 4.

Of the detected RF signal, a clock signal is generated by the PLL 5 in synchronization with the component of the clock pit CL shown in FIG. 2, and the clock signal is supplied to the tracking error detector 6. The tracking error detector 6 detects a tracking error from the clock signal and the RF signal. That is, as shown in FIG. 2, wobbled pits WB1 and WB2 are provided in the servo section in the track direction across the clock pit CL, and the wobbled pits WB1 and WB2 are symmetrically 1/4 from the track center.
The track pitch is offset. Therefore, the tracking error detector 6 detects the tracking error based on the difference in the deviation amount of the wobbled pits (RF level difference).

Since the output of the tracking error detector 6 is supplied to the optical system 3 via the adder 7, the optical system 3 is tracking-controlled so that the tracking error becomes zero. This state only indicates that there is no apparent tracking error because the output signal levels from both wobbled pits match, and if there is a radial skew, the output level of one wobbled pit Is larger than the other.

Therefore, when there is a radial skew, the head does not trace the center of the track even if the tracking error is actually zero. On the other hand, since the clock pit CL is arranged at the track center, the reproduction RF signal of the clock pit CL becomes a value smaller than the maximum value when the head does not trace the track center.

Therefore, in the present invention, the offset adder 8 adds a predetermined amount of offset to the tracking error signal via the adder 7. As a result, the head is displaced in the radial direction of the disk by an amount corresponding to the offset, so that the head can be moved to the center of the track by adjusting the offset amount to an appropriate value.
That is, an offset is added so that the level of the reproduction RF signal of the clock pit detected by the RF level detection unit 9 becomes the maximum value. In other words, this offset amount corresponds to the radial skew. Therefore, the tracking error signal at this time is supplied to the skew control circuit 10 to drive the head angle correction device 11 to adjust the angle of the head with respect to the radial direction of the disk 1.

If the level of the tracking error signal becomes zero in this state, it means that the head traces the center of the track and there is no tracking error. In this way, radial skew is eliminated.

The case where the present invention is applied to a magneto-optical disk device has been described above as an example, but the present invention can also be applied to other disk devices.

[0014]

As described above, the disk device of the present invention is
The head is positioned at the track center by adding an offset to maximize the level of the reproduction signal from the disc, and the skew angle is controlled so that the tracking error at this time becomes zero. The zero point coincides with the track center, which has the effects of reducing tracking errors and reducing the level of the RF signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a disk device configured by applying the present invention.

FIG. 2 is a diagram showing a pit array in a servo section.

[Explanation of symbols]

 1 Magneto-optical disk 2 Motor 3 Optical system 4 RF signal detector 5 PLL 6 Tracking error detector 7 Adder 8 Offset adder 9 RF level detector 10 Skew control circuit 11 Head angle correction device

Claims (1)

[Claims] 1. A level detection means for detecting a reproduction signal level from a disc, an offset addition means for adding an offset to a tracking servo system to adjust the level detected by the level detection means to the maximum, and the offset A disk drive, comprising: skew control means for controlling a radial skew so that a tracking error when added is minimized.