JP3104182B2 - Magnetic disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk used in a track servo type magnetic disk drive.

[0002]

2. Description of the Related Art As means for realizing high performance such as large capacity of magnetic disk, high track density and high speed seek,
Attention has been paid to track servo type magnetic disk devices. In a magnetic disk used in the track servo type magnetic disk device, data sectors and servo sectors are provided alternately on the surface of the magnetic disk, and the data sector and the servo sector are provided with a plurality of data tracks and servo tracks, respectively. FIG. 1 shows a conventional servo pattern, wherein 1 and 3 are data sectors and 2 is a servo sector. The servo data section is composed of a synchronization signal section 4 and a servo burst section 5, and the servo burst section 5 is shifted from the data track by a half track pitch and has servo track data A and servo burst data B having a track pitch width.
It is composed of

[0003]

To reproduce the data portion and the servo data portion, a reproduction circuit with an AGC (automatic gain control) as shown in FIG. 2 is often used. Since the detection signals of the data A and B serve as off-track information, it is necessary to fix the gain of the reproducing circuit to an appropriate value. Therefore, in the servo data portion of the conventional magnetic disk, the gain of the AGC-equipped reproducing circuit is fixed at a gain automatically determined by the detection signal of the data portion immediately before the servo data portion, and the servo burst data A and B are detected. The way to be done. But,
When the head H is off-track by 1/2 track pitch as shown in FIG. 1, that is, when the head H straddles two tracks, the direction of magnetization (shown by an arrow) of the adjacent track of the data part may be reversed. In this case, since the detection signal from the head coil becomes a value close to 0, the gain of the reproducing circuit with AGC works so as to become very large, and in this state, the gain of the reproducing circuit is fixed, and the servo data At the time of detection, there is a problem that the amplifier of the reproducing circuit is saturated and correct off-track information cannot be obtained.

It is a first object of the present invention to solve this problem. In order to detect the servo burst data A and B, a synchronizing signal for taking in these signals is required. However, conventionally, as shown in FIG. The non-signal part 41 is formed before the synchronizing bit 42, and the synchronizing signal is generated by the synchronizing bit 42 following the non-signal part 41. in this case,
In the case where the head H performs a 1/2 track pitch off-track as shown in the drawing, that is, the head H plays over two tracks, depending on the phase of the signal of both tracks,
For example, when the directions of the adjacent track magnetizations of the data portion are reversed as shown in the figure, the reproduced signal becomes very small. Therefore, this portion is erroneously detected as a non-signal portion, and the portion other than the synchronization bit subsequent thereto is detected. In some cases, a synchronization signal was generated in bits. It is a second object of the present invention to solve this problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above two problems, and the first invention is to solve the above first problem. In a magnetic disk in which sectors and servo sectors are provided alternately and a plurality of data tracks and servo tracks are provided in the data sector and the servo sector respectively, an AGC fixed portion is provided at each head of the servo track, and 2T
Is a minimum magnetization reversal interval, wherein the pattern of the AGC fixed portion is different for each track between the 4T continuous pattern and the 8T continuous pattern. According to a second aspect of the present invention, there is provided a magnetic recording apparatus comprising: a magnetic disk in which data sectors and servo sectors are alternately provided on a surface of a magnetic disk, and the data sectors and the servo sectors are provided with a plurality of data tracks and servo tracks, respectively. When the 2T is the minimum magnetization reversal interval, the synchronous signal generating section in each servo track is constituted by a non-signal section and a 3T continuous pattern.

A third aspect of the present invention is a magnetic disk for solving the first and second problems, wherein data sectors and servo sectors are provided alternately on the surface of the magnetic disk, and each of the data sector and the servo sector has a plurality of sectors. In a magnetic disk provided with a data track and a servo track, an AGC fixed section is provided at each head of the servo track, and then a synchronization signal generating section is provided.
The pattern of the AGC fixed part is 4T continuous pattern and 8T
A magnetic disk characterized in that it is configured to be different for each track in a continuous pattern, and wherein the synchronization signal generating section is configured by a non-signal section and a 3T continuous pattern.

[0007]

According to the first aspect of the present invention, since the AGC fixed portion in which the 4T continuous pattern and the 8T continuous pattern are alternately recorded for each track in the servo data portion is provided, even if the head is off-track by 1/2 track pitch, the magnetization is reduced. , The reproduction signal does not become very small as in the prior art, so that the gain of the reproduction circuit with AGC can be fixed to an appropriate value. In the second invention, the synchronizing signal generating section is set to the non-signal section and 3T.
Since a continuous pattern is used, the detection of a plurality of 3T continuous patterns within a certain time after detecting a non-signal portion can be used as a condition for generating a synchronization signal. The probability of detection is reduced.

[0008]

FIG. 3 shows a first embodiment of the present invention. Data sectors and servo sectors are alternately provided on the surface of a magnetic disk in the order of data sector 1, servo sector 21, data sector 3, and so on. And a servo sector provided with a plurality of data tracks and servo tracks, respectively, wherein an AGC fixing part 22 is provided at each head of the servo track, and when 2T is a minimum magnetization reversal interval, the AGC fixing part The AGC fixed section 22 is followed by a synchronizing signal generating section 33 composed of a non-signal section 331 and a 3T continuous pattern 332, in which the pattern 22 is different from the 4T continuous pattern 221 and the 8T continuous pattern 222 for each track. Next, servo burst data A and B are arranged as in the conventional case.

In the first embodiment shown in FIG. 3, as described above, the AGC fixing unit 22 in which the 4T continuous pattern 221 and the 8T continuous pattern 222 are alternately recorded for each track is provided, and the AGC reproduction is performed by the detection signal. Since the gain of the circuit is fixed and the subsequent servo burst data A and B are detected, a change in magnetization occurs even if the head H tracks a 1/2 track bit-off track as shown in the figure.
The reproduced signal does not become very small. Therefore, the gain of the reproducing circuit can be fixed to an appropriate value. In addition, the synchronization signal generation unit 33 is set to the non-signal unit 331 and the 3T continuous pattern
Since detection of a plurality of 3T continuous patterns 332 within a certain period of time after detection of the non-signal portion 331 can be used as a condition for generating a synchronization signal, it is only necessary to detect the presence or absence of a conventional bit. The probability of erroneous detection is smaller than that.
In addition, by forming the signal of the servo data 31 other than the synchronization signal generation unit in a pattern other than the 3T continuous pattern 332, the probability of the occurrence of the synchronization signal erroneous occurrence 31 can be further reduced. FIG. 4 shows a second embodiment. In the first embodiment shown in FIG. 3, the phase difference between the 4T continuous pattern 221 and the 8T continuous pattern 222 of the AGC fixing unit 22 is 0, but the phase is shifted. It is obvious that the same effect as in the first embodiment can be obtained in this case. FIG. 5 shows a third embodiment (specific embodiment). The difference from the first embodiment is that a servo ID section 35 is added. .

[0010]

According to the first aspect of the present invention, the gain of the AGC-equipped reproducing circuit is reliably fixed appropriately, and correct off-track information can be obtained. According to the second aspect, the probability of erroneous detection of the synchronization signal is reduced. Furthermore, since the third invention is related to the combination of the first invention and the second invention, there is an effect that the off-track information can be more correctly obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a servo pattern of a magnetic disk used in a conventional track servo type magnetic disk device.

FIG. 2 is an explanatory diagram of a reproduction circuit with AGC.

FIG. 3 is a diagram illustrating a servo pattern according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a servo pattern according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a servo pattern according to a third embodiment of the present invention.

[Explanation of symbols]

 1, 3 Data sector 2 Servo sector 4 Synchronous signal generation section 5 Servo burst section A, B Servo burst data 22 AGC fixed section 221 4T continuous pattern 222 8T continuous pattern 33 Synchronous signal generation section 331 No signal section 332 3T continuous pattern 35 Servo ID Department

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hideya Matahara 4084 Oji Miyadera, Iruma-shi, Saitama Pref. JP-A-2-116066 (JP, A) JP-A-2-44586 (JP, A) JP-A-1-92970 (JP, A) JP-A-63-100675 (JP, A) JP-A-61-204867 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 21/10 G11B 20/12

Claims (3)

(57) [Claims] 1. A magnetic disk in which data sectors and servo sectors are alternately provided on the surface of a magnetic disk, and a plurality of data tracks and servo tracks are provided in each of the data sector and the servo sector. Provide a fixed part,
A magnetic disk wherein the pattern of the AGC fixed portion is different for each track between a 4T continuous pattern and an 8T continuous pattern when 2T is a minimum magnetization reversal interval. 2. A magnetic disk in which data sectors and servo sectors are provided alternately on the surface of a magnetic disk, and a plurality of data tracks and servo tracks are provided in each of the data sectors and servo sectors. A magnetic disk, wherein a synchronizing signal generating section in each servo track is constituted by a non-signal section and a 3T continuous pattern. 3. A magnetic disk in which data sectors and servo sectors are provided alternately on the surface of a magnetic disk, and the data sector and the servo sector are provided with a plurality of data tracks and servo tracks, respectively. The fixed portion is provided with a synchronization signal generating portion next, and when the 2T is the minimum magnetization interval, the pattern of the AGC fixed portion is configured to be different for each track between the 4T continuous pattern and the 8T continuous pattern,
A magnetic disk, wherein the synchronizing signal generator comprises a non-signal part and a 3T continuous pattern.