JPS61208682A - Memory device - Google Patents

Abstract

PURPOSE:To improve the medium production yield by providing a defect detector and skipping means while removing part or all of the data tracks corresponding to defective portions on a servo disk out of use. CONSTITUTION:In a skip address part 31, there are three areas BA1-BA3 storing a byte address BA indicating the data skip leading position on the track, so that up to three defects on the track can be skipped. Hence it becomes possible to skip so as not to write data over an extent of a constant length from a byte position corresponding to the data track in association with the positions where defects 14 of the medium exist on the servo disk 1. When a comparator circuit 9 detects the medium defects, the track in its entirety may be put out of use as track in trouble or a certain length from the leading byte stored in the skip address part 31 may be skipped. In such a manner, use is made possible even if there is defect in the medium so that the production yield is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to storage devices such as magnetic disk devices and optical disk devices used to store information data.

Summary of the Invention The present invention reads servo information written on a servo disk with a servo head, demodulates the read servo information to generate a position error signal, and moves the data head to a predetermined position in accordance with the position error signal. In a storage device that performs reading and writing of data by positioning on a track, a defect detector detects a medium defect in the servo disk based on level fluctuations of the position error signal; The storage device is provided with a skip means that makes a part of the servo disk an unusable area so that all or part of the data track corresponding to the defective part on the servo disk is not used.

It can be used even when there is a media defect on a part of the servo disk, and the yield of media can be improved.

BACKGROUND ART Conventionally, as shown in FIG. 3, in a magnetic disk device or the like, one of the recording media is a servo disk 1, and a plurality of data disks 2 and servo disks 1 are connected to a spindle 3.
The servo disk 1 is connected coaxially with the servo disk 1, and one side of the servo disk 1 is used as a servo surface, and servo information including a position error signal etc. is recorded on the servo surface, and the servo information is read out by the servo head 4 and demodulated into a position error signal. The main method is a servo surface servo method in which the servo head 4 is positioned by a closed $ servo loop based on the position error signal, and the data head 5 interlocked with the servo head 4 is positioned on a predetermined track on the data disk 2. It is used.

FIG. 4 is a plan view showing the servo disk 1 and the servo head 4. FIG. However, the servo information stored concentrically on the servo disk 1 is displayed linearly. Odd number patterns 11 and even number patterns 12 are alternately recorded concentrically on the servo disk 1, and the servo head 4 just records the odd number pattern 1! When the position evenly straddles the even number pattern 12, the position error signal becomes 0 volts,
Corresponding to that position, the track center of the data disk 2 facing the data head 5 is determined. That is, the data head 5 is positioned on a predetermined data track on the data disk 2 by positioning the servo head 4 by closed loop control so that the read and demodulated position error signal of the servo head 4 becomes O. ° can be done.

But the medium defect on the servo surface! 4, the position error signal read by the servo head will be disturbed, making it impossible to correctly guide the data head onto a predetermined track. FIG. 5 shows that the servo head 4 is connected to the servo disk l.
The position error signal 15 read from the servo disk l when the position is between the odd number pattern 11 and the even number pattern 12 of
FIG. 3 is a diagram illustrating an example of a track N with a medium defect 14;
, it is shown that the position error signal 15 is disturbed. Therefore, media with such defects are discarded without being used because accurate positioning cannot be performed.

Problems to be Solved by the Invention In recent years, as the recording density of magnetic disk devices has increased, the number of defective position error signals due to media defects has tended to increase, resulting in the problem of poor media production yield. are doing.

The present invention is intended to solve the above-mentioned conventional problems and to improve the production yield of media by allowing the media to be used even if there are some defects.

Means for Solving the Problems The storage device of the present invention reads servo information written on a servo disk with a servo head and demodulates the read servo information to generate a position error signal.

In a storage device that positions a data head on a predetermined track according to the position error signal to read and write data.

a defect detector for detecting medium defects in the servo disk based on level fluctuations of the position error signal; and skipping means for skipping all or a part of the corresponding data track as an area in which data cannot be stored based on the output of the defect detector. Set up.

The present invention is characterized in that all or part of the data track corresponding to the defective portion on the servo disk is not used.

Embodiments of the Invention Next, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

That is, the signal read by the servo head 4 is demodulated by the demodulator 6, and the position error signal 15 is input to the positioning control circuit 7 and the differentiation circuit 8.

The positioning control circuit 7 controls the position of the servo head 4 so that the position error signal 15 becomes 0. On the other hand, the differentiation circuit 8 differentiates the position error signal 15 and inputs it to the comparison circuit 9. When the differential output of the error signal 15 becomes higher than a certain value, it is detected as a medium defect, and the output signal is inputted to the medium defect position data recording section IO. i.e. 1
If the level fluctuation of the position error signal 15 exceeds the allowable value, it is detected as a medium defect.6 In this embodiment,
The differentiating circuit 8 and the comparing circuit 9 constitute a ``defect detector for detecting medium defects in the servo disk''.

The medium defective position data recording section 10 receives an address signal AD indicating the current cylinder address, byte address, etc., and stores the cylinder address, byte address, etc. when the comparator circuit 9 detects the medium defect.

On the other hand, at the beginning of each data track 13 on the data disk 2, as shown in FIG. Home address (HA)
23 is written, with a gap (G2) of 24 (record 0 count)! ! (RO)25. CB) in the same figure, which follows the gap 26, etc., is a diagram showing details of the home address section 23, and includes a skip address section 31. A physical address section 32 indicating the physical address of the track. A flag byte section 33 indicating the quality of the track. Cylinder address section 34 indicating the cylinder address. It consists of a head address section 35 indicating a head address and an error correction code section 38. The skip address section 31 has three areas BAI NBA3 for storing byte addresses HA indicating the data skip start position on the track. Therefore, up to three defects on the track can be skipped.

These are areas that are conventionally used to skip a certain length of data from the leading position when a data error occurs, etc.; The byte address to be output is also recorded. Therefore, it is possible to skip so that data is not written within a certain length range from the corresponding byte position on the data track, corresponding to the position of the medium defect 14 on the servo disk l.

Further, when the comparator circuit 9 detects a medium defect, it indicates that the track is defective by writing 1'' into a predetermined bit of the flag byte section 33 of the corresponding data track. If "l" is written in a predetermined bit of the byte section 33, either all the tracks in question are not used as defective tracks, or
Or skip address part 3! A range of a certain length is to be skipped from the first byte stored in .

In this embodiment, even if the servo disk 1 has a medium defect 14, the storage device can be operated without using all or part of the corresponding track on the data disk 2. Therefore.

This has the effect of improving the yield of the medium.

Note that the data track skipping means corresponding to the defective portion of the servo disk 1 is such that an access control circuit (not shown) to the data disk 2 refers to data addresses, byte addresses, etc., and prevents the corresponding portion from being used. Various methods such as controlling can be used.

Effects of the Invention As described above, in the present invention, when there is a medium defect in the servo disk, all or part of the corresponding track on the data disk is skipped, so that it can be used even if there is a defect in the medium. Because it becomes possible to
This has the effect of improving production yield and making it possible to manufacture memory devices at lower cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. #12 is a diagram showing an example of a storage format of a data track, and FIG. 3 is a schematic diagram showing an example of a conventional storage device.
FIG. 4 is a diagram showing the servo information written on the servo disk and the servo head, and FIG. 5 is a diagram showing an example of a position error signal when the servo disk has a medium defect. 1. I-Zeginov h 9. Gigi disk, 3 Nissin spindle, 4: servo head, 5: data head, 6: demodulator, 7: positioning control circuit, 8: differentiation circuit, 9: comparison circuit , lO: medium defective position data recording section, !
1: odd number pattern, 12: even number pattern, 13: data track, 14: medium defect, 15: position error signal, 21
: index mark, 22, 24.28: gap, 23: home address, 25 double record O count part, 31: skip address child part, 32: physical address part, 33: flag byte part, 34 double cylinder address part , 35: head address section, 3B: error correction code section.

Claims (1)

[Claims] A servo head reads servo information written on a servo disk, demodulates the read servo information to generate a position error signal, and moves the data head to a predetermined track in accordance with the position error signal. A storage device that reads and writes data by positioning the servo disk, the storage device comprising: a defect detector that detects medium defects in the servo disk based on level fluctuations of the position error signal; and a corresponding data track detected by the output of the defect detector. and a skip means for skipping all or part of the data track as an area in which data storage is prohibited, so that all or part of the data track corresponding to the defective part on the servo disk is not used. Storage device.