JPH06215506A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To enable a normal operation even in the case a defect exists in a DC erase part which is taken as a reference of the servo information part for the positioning control. CONSTITUTION:The device is provided with a DC erase detection circuit 13 to detect the erroneous detection of the DC erase part which is taken as the reference signal of a positional information in a servo data storing area, and a decision circuit 23 for erroneous detection of the DC erase. By this arrangement, a decision signal 24 for erroneous detection of the DC erase is outputted to a servo processing circuit 19 when the erroneous detection is detected, thereby the erroneous operation due to the erroneous positional information is prevented, and the positioning control is performed based on the servo information of one before the information being stored in a positional information storage circuit 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device used for information processing.

[0002]

2. Description of the Related Art In recent years, the capacity of magnetic disk devices has been increased, and a so-called sector servo system, in which each data track is divided and a position reference signal is recorded, has begun to be used as a head positioning system (for example, Japanese Patent Laid-Open Publication No. Sho. 51-81603
Issue).

In this sector servo system, servo information is not recorded only on the servo surface as in the prior art, but a data storage area for storing the recording information and a servo data storage area for recording the positioning information, so-called servo information are alternately arranged. The magnetic head is positioned according to the servo information.

FIG. 3 shows a format diagram of the magnetic disk 1 using the sector servo system. The storage area of the magnetic disk, that is, the area between the concentric circles 2 and 3 shown in the figure is composed of a data storage area 4 and a servo data storage area 5. The recording information is stored in the data storage area 4, and the positioning information (servo information) is stored in the servo data storage area 5. Recorded in. The positioning information (servo information) in the servo data storage area 5 is used as a servo information section for positioning the magnetic head on the corresponding recording track. Reference numerals 5a and 5c indicate normal servo data storage areas, and 5b indicates a servo data storage area having a defect described later.

FIG. 4 is an enlarged view of a broken line portion of the recording area of the magnetic disk 1 shown in FIG. 3, showing a magnetic head (not shown) fixed by positioning control by rotation of the magnetic disk 1. On the other hand, the recording tracks 6 and 7 move in the direction of the arrow shown. Recording information is recorded in the data storage area 4, and a DC erase section 8 and a position information 9 which are timing reference signals are recorded in the servo data storage area 5.

[0006]

FIG. 5 shows a reproduction signal from the magnetic disk and a detection timing chart. The reproduction signal when the magnetic head moves on the recording track 6 shown in FIG. 4 is recorded in FIG. 5 (a). The reproduced signals when the magnetic head moves on the track 7 are shown in FIG. When the magnetic head moves on the recording track 6, it is in a normal state, the DC erase section 8 is detected, and a DC erase detection signal 14 which is a reference timing signal for detecting servo information is generated.
The reference timing signal 16 for detecting servo information for positioning control is generated. However, when the magnetic head moves on the recording track 7, the DC erase section of the servo data storage area 5b in the recording track 7 is generated. Defect 8
Since there is a ', the DC erase detection signal 14 cannot be detected. Therefore, the reference timing signal 16 for detecting the servo information cannot be generated, and the record information of the position information 9 cannot be taken in normally, so that a malfunction occurs in the servo system and an attempt is made to control with the incorrect position information. Off-track occurs, and it becomes difficult to write and read normal data.

Therefore, when a defect is found in the servo information portion, it is necessary to rewrite the sector servo signal or replace the magnetic disk itself, which lowers the productivity of the magnetic disk device.

The present invention solves such a conventional problem, and when the DC erase portion in the servo data storage area has a defect and the DC erase detection signal is determined to be erroneous detection, the servo data storage area is detected. The purpose is to invalidate the servo information of and to prevent the operation by the defective servo sector.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a DC erase detection circuit for detecting a DC erase portion that serves as a reference for the position of a magnetic disk, and servo information based on a DC erase detection signal detected by the DC erase detection circuit are provided. D indicating the time when the detection of the window gate signal and the DC erase detection signal, which are the reference timing signal for detection, is predicted.
A reference timing generating circuit for generating a C erase gate signal, and determining that an erroneous detection has occurred when the DC erase detection signal is not detected after a preset time D
When the DC erase erroneous detection determination circuit that generates the C erase erroneous detection determination signal and the DC erase erroneous detection determination signal are input, the position control is not performed based on the defective servo information, and the data is stored in the position information storage circuit. And a servo processing circuit for performing positioning control based on the previous servo information.

Further, when the DC erase detection signal is detected by the DC erase detection circuit, a sector count circuit for counting up the DC erase detection signal and a DC erase error detection determination signal from the DC erase error detection determination circuit. Is output, an erroneously detected sector storage circuit that stores the sector number of the sector count circuit and a servo processing circuit that performs positioning control based on the sector number stored in the erroneously detected sector storage circuit are provided. And

[0011]

According to the present invention, it is determined whether or not the DC erase portion serving as the reference signal of the position information in the servo data storage area can be normally detected, and the DC erase portion cannot be normally detected due to a defect or the like. In this case, the position on the magnetic disk is fixed, and the positioning control of the magnetic head due to incorrect position information is prevented.

Further, even if the DC erase portion of the servo information has a defect, the servo information read from the servo information is invalidated to prevent malfunction, so that rewriting of the sector servo signal or replacement of the magnetic disk itself is prevented. Disk devices become possible.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a magnetic disk device according to an embodiment of the present invention. In FIG. 1, 10 is a magnetic head that records or reproduces data on a magnetic disk (not shown), 11 is a head amplifier that amplifies a reproduction signal from the magnetic head 10, and 12 is a binarization that digitizes the reproduction signal. Circuits, which are the same as the conventional configuration of the magnetic disk device.

Reference numeral 13 is a DC erase detection circuit for detecting the DC erase section 8 (see FIG. 4) which serves as a reference signal of position information when a binarized signal is not input for a certain period, and 14 is a DC erase detection circuit 13 for DC. A DC erase detection signal indicating that the erase section 8 has been detected, 15 is a reference timing generation circuit for generating a reference timing signal for detecting servo information, and one is a reference timing signal for detecting servo information. Windgate signal 16 'and other one
One outputs a DC erase gate signal 22 indicating the time when the detection of the DC erase detection signal is predicted. 17 is a servo information detection circuit that detects servo information based on the wind gate signal 16 ', 18 is a servo analog processing circuit that processes servo information (analog information) from the head amplifier 11 based on the wind gate signal 16', and 19 is Servo processing circuit that performs calculations necessary for positioning the magnetic head 10, 20 is a positioning control circuit that performs phase compensation, etc., 21 is a voice coil motor for positioning the magnetic head 10, and 23 is a preset time. This is a DC erase error detection determination circuit that determines that error detection has occurred when the DC erase detection signal 14 is not detected.

Reference numeral 24 is a DC erase error detection determination signal indicating that the DC erase error detection circuit 23 has determined that the DC erase error is detected, and 25 is counted up each time the DC erase detection signal 14 is detected. A sector count circuit, 26 is an index signal detected once per revolution of the magnetic disk, 27 is an erroneously detected sector storage circuit for storing the sector number of the sector count circuit 25 in which erroneous detection has occurred, and 28 is an erroneously detected sector. A number output signal, 29 is a position information storage circuit.

The operation will be described below. The reproduced signal read from the magnetic head 10 is amplified by the head amplifier 11,
It is converted into digital data by the binarization circuit 12 and sent to a data processing circuit (not shown), a DC erase detection circuit 13 and a servo information detection circuit 17.

In the DC erase detection circuit 13, since there is no signal for a certain period, the DC erase detection signal 14
(See FIG. 2) is generated, and the reference timing generation circuit 15 outputs D
Based on the DC erase detection signal 14 from the C erase detection circuit 13, the servo information detection circuit 17 generates a reference timing signal 16 (see FIG. 5A) for detecting the servo information 30. The signal amplified by the head amplifier 11 is processed by the servo analog processing circuit 18, and analog processed data is sent to the servo processing circuit 19.

Then, after the servo processing circuit 19 performs the calculation necessary for the positioning control of the magnetic head from the servo information 30 from the servo information detection circuit 17 and the analog processing data from the servo analog processing circuit 18, the positioning control circuit 20 Positioning control is performed by performing processing such as position compensation by driving the voice coil motor 21, and position information of the magnetic head is stored in the position information storage circuit 29.

Here, the magnetic head 10 has the DC erase portion 8
When passing through the servo data storage area 5b having the defect 8a '(see FIG. 4), the extra pulse 8a is generated in the servo data storage area 5b having the defect in the reproduction signal shown in FIG. 5 (b). Since the DC erase detection circuit 13 detects the DC erase section 8 due to a non-signal period for a certain fixed period, the DC erase section 8 cannot be detected if the extra pulse 8a exists. Therefore, DC
A window gate signal that cannot be generated as the erase detection signal 14 and serves as a reference timing signal for detecting the servo information 30.
16 'cannot be generated.

In order to solve this problem, this embodiment is
A process is performed by determining the case where the DC erase portion is erroneously detected. Since the servo data storage area 5 shown in FIG. 3 is arranged at an equal angle on the magnetic disk 1, when the magnetic disk 1 is rotating at a constant rotation speed, the magnetic head 10 servos the magnetic head 10 at regular intervals. It passes through the data storage area 5. Therefore, it should pass through the next DC erase unit 8 after a certain time from the DC erase detection signal 14, and detection can be performed by generating the DC erase gate signal 22 by the reference timing generation circuit 15. The case of normal operation is shown in the timing chart for detecting defects in FIG. During the High period of this DC erase gate signal 22, the next DC erase detection signal 1
Since 4 occurs, DC erase error detection circuit 23
The C erase erroneous detection determination signal 24 is set to Low.

On the other hand, when the DC erase section 8 has the extra pulse 8a, the DC erase section 8 detects the DC erase section 8 when there is no signal for a certain period of time. As described above, the DC erase detection signal 14 is not output. When the DC erase gate signal 22 does not have the DC erase detection signal 14 during the High period, D when the DC erase gate signal 22 becomes Low.
The C erase erroneous detection determination circuit 23 can set the DC erase erroneous detection determination signal 24 to High to detect the occurrence of DC erase erroneous detection.

If DC erase error detection is determined, D
The DC erase error detection determination signal 24 output from the C erase error detection determination circuit 23 is transmitted to the servo processing circuit 19. The servo processing circuit 19 outputs a DC erase error detection determination signal 24
Is input, the defective servo data storage area 5
Correct positioning control is performed by performing processing such as driving the voice coil motor 21 based on the previous servo information stored in the position information storage circuit 29 without performing position control based on the information of b. It can be performed.

By recording the sector in which the erroneous detection is detected, more advanced processing can be performed. The sector count circuit 25 is set to D by the DC erase detection circuit 13.
Every time the C erase detection signal 14 is output, it counts up. Among a plurality of servo data storage areas 5 on the same circumference on the magnetic disk 1, an index signal 26 (not shown in FIG. 4) indicating a reference for one rotation is recorded in a certain servo data storage area. , When the index signal 26 is detected by the servo information detection circuit 17, the index signal
26 resets the counter output to the sector count circuit 25. With this configuration, the sector in which the index signal is detected is 0 sector, hereinafter, the DC erase detection signal 14
The sector number can be recognized by the sector count circuit 25 counting up each time is output.

The erroneously detected sector storage circuit 27 stores the sector number indicated by the sector count circuit 25 when the DC erase error detection determination circuit 23 determines that the DC erase error is detected and the DC erase error detection determination signal 24 is output. . Further, from the error detection sector number output signal 28 already stored in the error detection sector storage circuit 27 and the current sector number indicated by the sector count circuit 25, the error detection of the next DC erase part is predicted, It is possible to perform the processing for correct positioning in the same manner as described above.

In this case, the erroneous detection sector storage circuit 27 may store a plurality of erroneously detected sectors in a track, or may store the sectors of DC erase erroneous detection in all tracks.

In this embodiment, a microcomputer is used as the servo processing circuit, but it goes without saying that the hardware can be used.

Although the DC erase detection circuit malfunctions due to the extra pulse generated by the defect in the DC erase portion, it goes without saying that the DC erase error detection due to noise or the like can be dealt with.

Further, in this embodiment, the complement is made based on the previous position information stored in the position information storage circuit, but the complement is made based on the position information of the sectors before and after the defective portion. It goes without saying that the correct track position information of the sector of the defective portion is stored, and when the defective portion of the corresponding sector comes, the effect is obtained even if the stored position information is used. Absent.

[0030]

As described above, in the magnetic disk device of the present invention, when the DC erase portion in the servo data storage area is defective and the DC erase is determined to be erroneous detection,
Since the servo information from the servo data storage area is invalidated and the operation due to the defective servo sector is prevented, it is possible to prevent incorrect position control by operating according to the defective servo information as in the conventional case. .

Further, it is possible to provide a magnetic disk and a magnetic disk device capable of improving the productivity of the magnetic disk and reducing the manufacturing cost because it is not necessary to rewrite the servo sector or replace the magnetic disk as in the conventional case. .

[Brief description of drawings]

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

FIG. 2 is a timing diagram for detecting the defect of FIG.

FIG. 3 is a format diagram of a magnetic disk using a sector servo system.

FIG. 4 is a detailed view of a magnetic disk format in which a broken line portion of FIG. 3 is enlarged.

FIG. 5 is a reproduction signal from the magnetic disk and a detection timing chart.

[Explanation of symbols]

10 ... Magnetic head, 11 ... Head amplifier, 12 ... Binarization circuit, 13 ... DC erase detection circuit, 14 ... DC erase detection signal, 15 ... Reference timing generation circuit, 16 ... Reference timing signal 16 '... Wind gate signal, 17 ... Servo information detection circuit, 18 ... Servo analog processing circuit,
19 ... Servo processing circuit, 20 ... Positioning control circuit, 21 ...
Voice coil motor, 22 ... DC erase gate signal,
23 ... DC erase error detection determination circuit, 24 ... DC erase error detection determination signal, 25 ... Sector count circuit, 26 ...
Index signal, 27 ... False detection sector memory circuit, 28
… False detection sector number output signal, 29… Position information storage circuit, 30… Servo information.

Claims (2)

[Claims] 1. A DC erase detection circuit for detecting a DC erase portion serving as a reference for the position of a magnetic disk, and the DC.
A reference for generating a window erase signal, which is a reference timing signal for detecting servo information based on the DC erase detection signal detected by the erase detection circuit, and a DC erase gate signal indicating a time at which the detection of the DC erase detection signal is predicted. A timing generation circuit, a DC erase error detection determination circuit that determines an error detection when the DC erase detection signal is not detected after a preset time, and generates a DC erase error detection determination signal;
When an erase erroneous detection determination signal is input, position control based on defective servo information is not performed, and positioning control is performed based on the previous servo information stored in the position information storage circuit. A magnetic disk device characterized by the above. 2. A sector count circuit that counts up the DC erase detection signal when the DC erase detection signal is detected by the DC erase detection circuit;
When a DC erase error detection determination signal is output from the erase error detection determination circuit, an error detection sector storage circuit that stores the sector number of the sector count circuit and a sector number stored in the error detection sector storage circuit The magnetic disk drive according to claim 1, further comprising a servo processing circuit for performing positioning control.