JPH07225964A - Disk servo device - Google Patents

Abstract

PURPOSE:To suppress a tracking positional deviation to be small even though a correct tracking error signal is not obtained in the address reproducing period of a disk. CONSTITUTION:This device is provided with an address detector 11 detecting addresses being in reproducing data, an address window generator 12 generating a window signal indicating a next address period and an extrapolation interpolator 13 generating the replacement signal of the tracking error signal. Then, in a period when the replacement signal of the tracking error signal is generated from the tracking error signal preceeding the address part on the disk and the address window signal is outputted, a tracing actuator is driven by changing over the tracking error signal to the replacement signal. In a period when the address window signal is outputted without using the extrapolation interpolator, a zero value is allowed to be inputted to a servo filter 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk servo device used for positioning a head of an optical disk device or a magnetic disk device for storing data, audio, video, etc.

[0002]

2. Description of the Related Art FIG. 4 shows the structure of a conventional disk servo apparatus of this type. In FIG. 4, 1 is a disk as a recording medium, 2 is a head for recording / reproducing data on / from the disk 1, 3 is a servo filter of a tracking servo for positioning the head 2 on a track for recording / reproducing on the disk 1, and 4 is a servo filter. It is an actuator drive circuit for driving the tracking coil of the head 2.

The operation of the conventional disk servo device constructed as described above will be described below. On the disk 1, a guide signal indicating a track for recording / reproducing data is written in advance. The head 2 detects a tracking error signal indicating the amount of deviation from the tracking center from this guide signal. The tracking error signal passes through the servo filter 3 and is current-amplified by the actuator drive circuit 4 to drive the tracking actuator coil of the head 2. Servo filter 3 here
Is for ensuring head tracking position accuracy and stability of the servo control system. This control system works so that the tracking error signal is zero, that is, the head 2 follows the tracking center of the disk 1.

In this way, the head can be made to follow the track of the disk also by the above-mentioned conventional disk servo device.

[0005]

However, in the above-mentioned conventional disk servo apparatus, in the case of a disk in which there is no tracking guide signal around the address section on the disk, the period during which the address section is passing is There is a problem that the tracking error signal cannot be detected and an incorrect value is input to the servo filter. As a result, the head gradually shifts from the center of tracking,
There has been a problem that the tracking position shift amount at the head of the data recording area immediately after passing through the address portion becomes large.

The present invention solves such a conventional problem, and an object thereof is to provide an excellent disk servo device capable of reducing a tracking error immediately after passing through an address portion.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a means for generating a window signal indicating an address period in reproduced data and a tracking error substitute signal from the latest tracking error signal. And means for selecting either the tracking error signal detected from the disk or an alternative signal as an input to the tracking servo filter.

The present invention also comprises means for generating a window signal indicating the address period in the reproduced data, and means for selecting either the tracking error signal detected from the disk or a zero value as an input to the tracking servo filter. It is a thing.

[0009]

Therefore, according to the present invention, the error occurs when the tracking guide signal has a discontinuity while passing through the address portion,
Since the tracking servo can be applied without using an erroneous tracking error signal, there is an effect that the tracking error can be reduced immediately after passing through the address portion.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the first embodiment of the present invention. In FIG. 1, reference numeral 11 denotes an address detector, which inputs a reproduction signal from the disk 18 by the head 17. An address window generator 12 is connected to the address detector 11 to generate a window signal indicating the address period in the reproduction signal. An extrapolation interpolator 13 receives the tracking error signal detected by the head 17 and is connected to the terminal B of the switcher 14. A tracking error signal that does not pass through the extrapolation interpolator 13 is connected to the terminal A of the switch 14 as an input. Reference numeral 15 is a servo filter, which receives the output of the switching device 14 and is connected to the actuator drive circuit 16. The output of the actuator drive circuit 16 is the head 17
It is connected to the tracking coil of.

Next, the operation of the first embodiment will be described. In the first embodiment, the head 17 reads the guide groove indicating the track on the disk 18 and detects the tracking error signal. Further head 17
Reads a signal from the disk 18, and the address detector 11 detects an address indicating the beginning of a unit (sector or the like) of a series of data. The address window generator 12 generates an address window signal indicating the period in which the next address should be detected from the cycle of addresses written on the disk 18. FIG. 2 shows the periphery of the address portion on the disk 18. In FIG. 2, reference numeral 19 is a tracking guide groove indicating a track boundary, and 20 is an address portion. The address window signal is output only during the period of the address section 20 in FIG.

Returning to FIG. 1, the extrapolation interpolator 13 predicts and outputs the tracking error signal after the current time by extrapolation from the most recent tracking error signal using a means such as linear interpolation or curve fitting. While the address window signal is not output, the correct tracking error signal is obtained from the head 17, the switching device 14 is tilted to the terminal A side, and the tracking error signal detected by the head 17 is directly input to the servo filter 15. The actuator drive circuit 16 drives the tracking coil of the head 17 to apply servo. The head 17 reaches the address section 20, and the address window generator 12
Switch outputs an address window signal
4 is moved to the terminal B side, the output of the extrapolation interpolator 13 is input to the servo filter 15 as an alternative signal of the tracking error, and the actuator drive circuit 16 drives the tracking coil of the head 17. The head 17 has an address section 20.
After passing through, the switch 14 is returned to the terminal A side again, and the servo is operated by the tracking error signal.

As described above, according to the first embodiment,
Address part 20 where the tracking guide groove 19 is interrupted
Even if the head 17 passes through, the head 17 is driven by the alternative signal predicted from the correct tracking error signal in the past, and it is not necessary to use an erroneous tracking error. Therefore, the tracking error after passing through the address section 20 should be reduced. It has the advantage that

(Embodiment 2) Next, a second embodiment of the present invention will be described. FIG. 3 shows the configuration of the second embodiment of the present invention. The configuration of the second embodiment is
The difference from the first embodiment is that an extrapolation interpolator is not used. Figure 3
In the figure, reference numeral 21 is an address detector, and the reproduction signal from the disk 27 is inputted by the head 26. An address window generator 22 is connected to the address detector 21. Reference numeral 23 denotes a switch, which inputs the tracking error signal detected by the head 26 when it is tilted to the terminal A side, and its output is connected to the servo filter 24. Further, to the terminal B of the switch 23, a signal corresponding to the "zero value" of the servo signal is connected as an input. The output of the servo filter 24 is connected to the actuator drive circuit 25. The output of the actuator drive circuit 25 is connected to the tracking coil of the head 26.

Next, the operation of the second embodiment will be described. In the second embodiment, the head 26 has a tracking guide groove 1 that indicates a track on the disk 27.
9 is read and the tracking error signal is detected. Further, the head 26 reads a signal from the disk 27,
The address detector 21 detects the address portion 20 indicating the head of a series of data units. The address window generator 22 generates an address window signal indicating the period in which the next address portion 20 should be detected, as in the first embodiment, from the cycle of the address portion 20 written on the disk 27. .

While the address window signal is not output, the correct tracking error signal is obtained from the head 26, the switch 23 is tilted to the terminal A side, and the tracking error signal detected by the head 26 is directly applied to the servo filter 24. Then, the actuator driving circuit 25 drives the tracking coil of the head 26 to apply servo. When the head 26 reaches the address unit 20 and the address window generator 22 outputs the address window signal, the switch 23 is tilted to the terminal B side, a zero value is input to the servo filter 24, and the actuator drive circuit 25 drives the head 26. Drive the tracking coil. That is, while the address window signal is being output, it is considered that there is no deviation from the tracking position of the head 26, and control is stopped. When the head 26 has finished passing through the address section 20, the switch 23 is returned to the terminal A side again, and the servo is operated by the tracking error signal. As described above, also in the second embodiment, the same effect as that of the first embodiment can be obtained.

[0017]

According to the present invention, as is apparent from the above-described embodiment, the head is driven by the alternative signal of the tracking error during the address reproduction period of the disk, so that the tracking guide signal on the disk is discontinuous. Even if a correct tracking error signal is not obtained in the vicinity of the address portion, the amount of tracking position deviation after passing through the address portion can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a disk servo device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of the periphery of a disc address portion of a disc

FIG. 3 is a block diagram showing a configuration of a disk servo device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional disk servo device.

[Explanation of symbols]

 11 Address Detector 12 Address Window Generator 13 Extrapolation Interpolator 14 Switcher 15 Servo Filter 16 Actuator Drive Circuit 17 Head 18 Disk 19 Tracking Guide Groove 20 Address Part 21 Address Detector 22 Address Window Generator 23 Switcher 24 Servo Filter 25 actuator drive circuit 26 head 27 disk

Claims (2)

[Claims] 1. A means for generating a window signal indicating an address period in reproduced data, a means for extrapolating a tracking error substitute signal from the most recent tracking error signal, and detection from a disk as an input to a tracking servo filter. Disk servo device having means for selecting either the tracking error signal or the alternative signal. 2. A disk servo comprising means for generating a window signal indicating an address period in reproduced data and means for selecting either a tracking error signal detected from a disk or a zero value as an input to a tracking servo filter. apparatus.