JPH07192208A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk device which can surely prevent the positioning accuracy of a head from being lowered by servo interference without disturbing the miniaturization of the magnetic disk device. CONSTITUTION:At the time of diagnosis when turning on a power source or the like, write is executed to a WRITE check track for diagnosis and at this time, the amount of the deviation of a position signal 11 from the center of the track caused by the servo interference is measured by an A/D converter 24 and a microprocessor 25. When the deviation amount is large, the microprocessor 25 changes the pulse duration of a SYNC-SS signal 17 by controlling a SYNC-SS preparing circuit 16, and the change of the signal level of the position signal 11 (the off-track of a servo head 5 and a data head 6) caused by the servo interference is controlled so as to be minimized by intensively shifting the timing of write data 21 and a carry waveform at a peak hold circuit 10.

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, and more particularly to a technique effectively applied to positioning control of a data head.

[0002]

2. Description of the Related Art Magnetic disk devices are widely used as external storage devices in computer systems. By the way, in such a magnetic disk device, it is important to improve the accuracy of positioning and tracking control of the head with respect to tracks concentrically arranged on the magnetic disk as a storage medium in order to maintain the reliability of the operation.

Conventionally, as to such a head positioning technique, for example, as disclosed in Japanese Patent Laid-Open No. 1-73579, an acceleration detecting means is arranged in a part of the device so that vibration applied to the device is generated. A technique has been known in which the head position deviation caused by vibration is minimized by detecting and feeding back the detection result to a positioning system.

[0004]

However, in the case of the above-mentioned prior art, although there is a certain effect as a countermeasure against the positional deviation of the head due to mechanical factors such as vibration, the magnetic flux generated from the data head during data writing. However, no consideration was given to the deterioration of the positioning accuracy (hereinafter, referred to as servo interference at the time of writing) due to the fact that it acts as noise on the servo head that reads the servo information.

As a measure for preventing such servo interference, a shield member is arranged so that the magnetic flux of the data head does not overlap with the magnetic flux of the servo head, and the arrangement position is devised so that both are magnetically coupled. However, due to miniaturization of the magnetic disk device, there is a limit to the addition of members and the arrangement of the servo head and the data head.

An object of the present invention is to provide a magnetic disk device capable of reliably preventing a decrease in head positioning accuracy due to servo interference without hindering downsizing of the magnetic disk device.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0008]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

According to the present invention, a magnetic disk including a servo surface on which servo information is written and a data surface on which normal data is written, a servo head for reading servo information from the servo surface, and data for the data surface are recorded. A data head for writing and reading, and an actuator for supporting the servo head and the data head to move them in a radial direction with respect to the magnetic disk,
In a magnetic disk device comprising a positioning control means for performing a positioning operation on a data surface of a data head by controlling an actuator based on the servo information, the data on the data surface by the data head at the detection timing of the servo information by the servo head Is provided with timing control means for variably controlling the write timing.

[0010]

According to the magnetic disk device of the present invention described above,
The timing control means sets and controls the timing of data writing by the data head so as to deviate from the peak time of the detected waveform level of the servo information by the servo head.

As a result, it is possible to minimize the error in the positioning control of the data head and the servo head caused by the magnetic flux emitted from the data head being superimposed on the servo information and detected by the servo head, and the accuracy of the positioning control. Is improved.

Further, there is no restriction in mechanical design such as addition of an extra mechanism such as a shield member, and distance of the data head from the servo head, and there is no obstacle to miniaturization.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of the configuration of a magnetic disk device according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing an example of its action, and FIG. 4 is its action. It is a flowchart which shows an example.

The plurality of magnetic disks 1 includes a spindle 1a.
It is fixed coaxially to and rotates. A VCM actuator 7 that is movable in the radial direction of the magnetic disk 1 is provided on the side of the magnetic disk 1. The VCM actuator 7 faces each of the servo surface 4 and the plurality of data surfaces 23 of the magnetic disk 1. The servo head 5 and the plurality of data heads 6 are supported in a posture.

The servo information written on the servo surface 4 of the magnetic disk 1 is read by the servo head 5, amplified by the amplifier 8 and the amplifier 9, and the position signal 11 is generated by the peak hold circuit 10. The position signal 11 is used by the error amplifier 12, the power amplifier 13, and the VCM actuator 7 to control the positioning of the servo head 5 and the data head 6 at the track centers of the servo surface 4 and the data surface 23.

Further, the rotation synchronization information included in the servo information is input to the SYNC_PLS creating circuit 14 and S
The YNC_PLS signal 15 is created. SYNC_PL
The S signal 15 is input to the SYNC_SS creation circuit 16 and is a SYNC_SS signal 17 which is an input signal for rotation synchronization.
Is created. The SYNC_SS signal 17 is the PLO circuit 2
A PLO_CLK signal 20 that is a clock synchronized with the rotation of the magnetic disk 1 is input to the signal generator 6.

At the time of writing data, the write data creating circuit 18 creates write data 21 obtained by synchronizing the NRZ_WRITE_DATA 19 with the PLO_CLK signal 20. The write data 21 is written on the data surface 23 by the data head 6 via the write amplifier 22.

In this case, a microprocessor 25 is connected to the SYNC_SS creation circuit 16, and the S 25
SYNC generated in the YNC_SS creation circuit 16
The operation of controlling the _SS signal 17 is performed. That is, the position signal 11 from the peak hold circuit 10 is input to the microprocessor 25 via the A / D converter 24, and the SYNC_SS signal 17 is controlled based on the position signal 11.

FIG. 2A shows an example of general servo information on the servo surface 4 in the magnetic disk device. FIG. 2B shows a carry waveform that is a read waveform from the servo head 5 when the servo head 5 is positioned at the track number N. Servo head 5 on track N
Is displaced by the positioning control circuit (peak hold circuit 10, error amplifier 12, power amplifier 13) in the radial direction so that the read voltages V ₀ and V _E from the position information 2 and the position information 3 become equal. Controlled.

On the other hand, when noise Ns due to servo interference at the time of writing data by the data head 6 is superimposed on the carry waveform, the servo head is adjusted so that V ₀ + Ns and V _E become equal in magnitude as shown in FIG. 3A. 5 is controlled,
The servo head 5 produces an off-track which is displaced from the track center.

The timing of the noise Ns superimposed on the carry waveform is synchronized with the rising and falling edges of the waveform of the write data 21.

Now, as shown in FIG. 3A, when the noise Ns is superimposed near the peak of the read waveform of the position information,
Although the servo head 5 is displaced in the radial direction by the noise Ns, as shown in FIG. 3B, when the timing is deviated from the peak of the read waveform of the position information by Δt, the detection level V ₀ of the original carry waveform is exceeded. Does not increase, the servo head 5 does not go off-track. That is,
If there is servo interference during data writing, the servo interference can be avoided by shifting the timing of the write data 21.

SYNC_ generated from the SYNC_PLS signal 15 created from the rotation synchronization information of the carry waveform.
Falling edge of SS signal 17 and write data 21
Are synchronized, the microprocessor 25 in this embodiment controls the SYNC_SS generation circuit 16 to make the pulse width W of the SYNC_SS signal 17 variable.

An example of the operation of this embodiment will be described below with reference to the flow chart of FIG.

First, at the time of diagnosing the initial sequence when the power is turned on, or after confirming that it is in the idle state (step 101), seek (move) to the diagnostic WRITE check track provided on the data surface 23 (step). 102), the servo interference amount at the time of writing data is checked.

That is, the offset amount V ₁ of the position signal 11 from the track center when data is not being written is measured by the microprocessor 25 via the A / D converter 24 (step 103).

Next, the data head 6 writes the worst data of a predetermined pattern in which servo interference is likely to occur at the time of writing data, and the offset amount V ₂ of the position signal 11 from the track center at that time is written.
Via the A / D converter 24 to the microprocessor 25
Is measured (step 104).

Next, (V ₂ −V ₁ ) is calculated as the servo interference amount at the time of writing data (step 105) and compared with the allowable value V _S of the servo interference amount (step 10).
6).

When (V ₂ −V ₁ )> V _S , the microprocessor 25 controls the SYNC_SS generation circuit 16 in order to shift the peak hold and the magnetization inversion timing of the write data by Δt when the position signal is generated. The pulse width W of the SYNC_SS signal 17 is increased by Δt (step 108), step 104 and step 105 are repeated (step 109), and in this repetition (V ₂ −V ₁ )> V _S , SYNC
The pulse width W of the _SS signal 17 is reduced by Δt (step 110), and once again step 104 and step 1
05 is repeated (step 107), but (V ₂ −
If V ₁ )> V _S , the pulse width W of the SYNC_SS signal 17 is set so that (V ₂ −V ₁ ) is minimized (step 111).

By the above operation, servo interference at the time of writing data can be minimized.

Further, in order to magnetically isolate the servo head 5 and the data head 6, a bulky structure such as a shield member is provided, or the distance between the servo head 5 and the data head 6 is increased. It is not necessary to take measures to prevent downsizing, and it is possible to achieve both prevention of servo interference and downsizing of the magnetic disk device.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

[0034]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, according to the magnetic disk device of the present invention, it is possible to reliably prevent a decrease in head positioning accuracy due to servo interference without hindering downsizing of the magnetic disk device. To be

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of a magnetic disk device that is an embodiment of the present invention.

FIG. 2A to FIG. 2C are diagrams showing an example of the action.

3A and 3B are diagrams showing an example of the operation.

FIG. 4 is a flowchart showing an example of the operation.

[Explanation of symbols]

 1 magnetic disk 1a spindle 2 position information 3 position information 4 servo surface 5 servo head 6 data head 7 VCM actuator 8 amplifier 9 amplifier 10 peak hold circuit 11 position signal 12 error amplifier 13 power amplifier 14 SYNC_PLS creation circuit 15 SYNC_PLS signal 16 SYNC creation Circuit 17 SYNC_SS signal 18 Write data creation circuit 19 NRZ_WRITE_DATA 20 PLO_CLK signal 21 Write data 22 Write amplifier 23 Data surface 24 A / D converter 25 Microprocessor 26 PLO circuit

Claims (1)

[Claims] 1. A magnetic disk including a servo surface on which servo information is written and a data surface on which normal data is written, a servo head for reading the servo information from the servo surface, and the above-mentioned data surface. A data head for writing and reading data, an actuator for supporting the servo head and the data head to move in a radial direction with respect to the magnetic disk, and controlling the actuator based on the servo information. A magnetic disk device comprising a positioning control means for performing a positioning operation of the data head with respect to the data surface, wherein the data on the data surface by the data head with respect to the detection timing of the servo information by the servo head. Writing of timing A magnetic disk device comprising a timing control means for variably controlling the magnetic field.