JPS6247882A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To attain the positioning of a magnetic head with higher accuracy by making use of the information on the eccentricity detected from the servo track closest to the target data track among plural servo tracks on a disk. CONSTITUTION:A disk medium 2 contains plural servo tracks and a magnetic head 4 is positioned at a servo track closest to the target data track. The head 4 reads the servo track and detects the position error signal through a position error detecting circuit 5. These detected position error signals are stored temporarily in an internal memory of a drive circuit in an amount equivalent to a round synchronously with the revolution of the medium 2. Then the head 4 is shifted to the target data track by a step motor 7 and positioned there. Here the magnetic head 4 can be accurately positioned at all data tracks although the degrees of eccentricity are different between the most outer circumferential areas and the center areas since plural servo tracks are provided.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic disk device.

[Prior art and its problems]

In a floppy disk device, a carriage containing a magnetic head is driven and positioned by a step motor in a direction perpendicular to a data track in units of the positioning pitch of the step motor, and data is recorded on the medium surface.
Read data that has already been recorded. At this time, the track pitch of the data track is defined as one pitch of the step motor or an integral multiple thereof.

On the other hand, in recent years, the recording density of floppy disk devices has improved markedly, and in particular, in perpendicular magnetic recording, the recording linear density has been realized to be one order of magnitude higher than that in conventional longitudinal recording.

Therefore, it is desired to improve the track density as well as the linear density of recording, and the storage capacity of the entire device is increasing.

In addition, unlike fixed magnetic disks, in floppy disk drives, the disk medium is replaceable, and the substrate material of the disk medium itself is soft, so temperature
Easily deformed due to changes in humidity. Therefore, when replacing the disk or due to environmental changes, the data track, which is supposed to be concentric with the center of the spindle that rotates the disk, may shift its center and become distorted and eccentric from the concentric circle. will occur. This eccentricity rarely causes a problem as long as the track density is small, but
In order to increase storage capacity, and in particular to improve track density, the track pitch becomes smaller, and when the eccentricity of the data track becomes a value that cannot be ignored relative to the track pitch, the magnetic head will be able to accurately record the data. When recording data, crosstalk from adjacent tracks increases and data becomes unreliable during recording and playback. Furthermore, there is a disadvantage that data readability becomes impossible.

[Purpose of the invention]

As described above, an object of the present invention is to provide a magnetic disk device that can stably position a magnetic head on all eccentric data tracks even when the track pitch is reduced.

[Structure of the invention]

The present invention provides a disc-shaped recording medium provided with concentric data tracks and a plurality of servo tracks and rotated by a drive device, and a transducer for recording and reproducing data that is arranged at a radius of the recording medium. a step motor that moves the transducer stepwise by a predetermined pitch in a direction; and a step motor that moves the transducer stepwise by a predetermined pitch in a direction; a position error detection circuit that outputs an error signal; and a position error detection circuit that outputs an error signal to the target data track in synchronization with the rotation of the recording medium before the transducer records and reproduces data on the target data track. a memory for recording the position error signal for one rotation regarding the closest servo track; and a memory for recording the position error signal for one rotation with respect to the closest servo track, and a memory for recording the position error signal stored in the memory when the transducer records and reproduces data with respect to the target data track. and a control circuit that controls the step motor so that the transducer is continuously moved within the predetermined pitch.

[Effect]

Next, the present invention will be explained in detail. A disk-shaped recording medium provided with concentric data tracks and a plurality of concentric servo tracks is rotated by a drive device. The transducer is moved in the radial direction of the recording medium with respect to the rotating recording medium while being positioned step by step at a predetermined pitch by a step motor, and records and reproduces data while being positioned. The position error detection circuit detects a relative positional deviation between the servo track and the transducer based on data of the servo track reproduced by the transducer when the transducer is located at a position corresponding to the servo track. outputs a position error signal. When the recording medium is eccentric, the servo track moves toward and away from the center of the transducer during one rotation of the recording medium, and this is detected as a relative positional deviation. In addition, since the servo track and data track are provided concentrically,
The relative positional misalignment between the transducer and the servo track closest to the target data track for recording and reproduction can be considered to be the same as the relative positional misalignment between the target data track and the transducer. Therefore, before the transducer records or reproduces data on the target data track, it stores in memory the position error signal for one revolution regarding the servo track closest to the target data track in synchronization with the rotation of the recording medium. Then, when the transducer records and reproduces data on the target data track, the step motor is controlled according to the stored position error signal, and the transducer is continuously, that is, linearly, within the above-mentioned predetermined pitch. Moving the transducer allows accurate positioning of the transducer relative to the data track.

〔Example〕

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

FIG. 1 shows a block diagram of an embodiment of the invention. The carriage 3 including the magnetic head 4 is driven stepwise by a step motor 7 in the radial direction of the disk medium 2 at a predetermined pitch. At this time, the disk medium 2 is rotated by the spindle motor 1. A plurality of servo tracks are provided on this disk medium, as will be explained later. The magnetic head 4 includes a position error detection circuit 5.
The position error detection circuit 5 is connected to the step motor 7 via the drive circuit 6.

When recording or reproducing data on a target data track, the magnetic head 4 is first positioned on the servo track closest to the target data track. As will be explained later, the magnetic head 4 reads the servo track, and the position error detection circuit 5 detects a position error signal indicating the relative position of the servo track with respect to the magnetic head 4. The detected position error signal is stored in a memory inside the drive circuit 6 in synchronization with the rotation of the disk medium 2 for one revolution. In this way, after the positional error for one rotation of the servo track with respect to the magnetic head 4 of the disk medium 2 is accumulated, the magnetic head 4 is moved by a predetermined pitch to the target data track and positioned.

At this time, as mentioned above, if the disk medium 2 has eccentricity and the track density is high, positioning using only the step motor 7 will result in a large misalignment between the magnetic head 4 and the data track. The reliability of recording and playback decreases. Here, since the eccentricity of the servo track closest to the target data track and the eccentricity of the data track can be considered to be the same in frequency and quantity,
The magnetic head A can be accurately positioned on the data track 7 by linearly operating the step motor 7 within the positioning pitch by the drive circuit 6 in response to the positional error stored in the memory. At this time, since a plurality of servo tracks are provided, the magnetic head can be positioned more accurately with respect to all data tracks even if the amount of eccentricity is different between the vicinity of the outermost periphery and the vicinity of the center of the disk.

FIG. 2 shows a block diagram of a position error detection circuit 5 for detecting a relative position error between the magnetic head 4 and the servo track 11. The position error detection circuit 5 has a magnetic head 4 at its input end.
The preamplifier 12 is connected to the preamplifier 12. The output terminal of the preamplifier 12 is connected to one input terminal of a differential amplifier 17 via a band pass filter 13 and an envelope detector 15, and is connected to one input terminal of a differential amplifier 17 via a band pass filter 14 and an envelope detector 16. 17. The output terminal of the differential amplifier 17 is connected to the memory 18 of the drive circuit 6. Note that the rotation synchronization clock signal 19 is manually input to the memory 18.

The disk medium 2 has two different frequencies <f+,
Two servo tracks 11 are provided near the outermost periphery and near the middle portion. As described above, before the magnetic head 4 is positioned to the target data track, it is first positioned at the center of the servo track closest to the target data track by the step motor. Therefore, the magnetic head 4
reads out signals of two different frequencies, and preamplifier 1
The signal is amplified by 2 TE and output to band pass filters 13 and 14. The passing frequencies of the bandpass filters 13 and 14 correspond to two different frequencies (f, , f2) of the servo track 11, respectively. Separates and outputs the detected frequencies. That is, if the servo track is biased to one side with respect to the magnetic head 4, the output signal of one corresponding frequency becomes large and the output signal of the other frequency becomes small. Envelope detectors 15 and 16 receive the outputs of bandpass filters 13 and 14, respectively, and detect the amplitudes of the readout signals for different frequencies of the servo tracks separated by the bandpass filters. Differential amplifier 17 connects envelope detectors 15 and 1
Calculate the difference between the outputs of 6. By doing this,
The output of the differential amplifier 17 represents a signal proportional to the positional error of the magnetic head 4 with respect to the servo track 11. By storing the position error signal thus detected for one rotation in the memory 18 using the rotation synchronization clock signal 19 synchronized with the rotation of the disk medium 2,
By using this eccentricity information when recording and reproducing data on the data track, accurate tracking becomes possible.

A block diagram of the drive circuit 6 is shown in FIG. 3(a).

The drive circuit 6 is equipped with the above-mentioned memo 'J18. The memory 18 is connected to the switch 2 via a read-only memory (ROM>21) and a pulse width modulation circuit (PWM circuit) 22.
It is connected to the input terminal of 4. In addition, a step signal 25 and a direction signal 2 are input from an external controller (not shown).
6 is supplied with the step drive circuit 23 which is connected to the switch 24.
is connected to the input end of the The output end of the switch 24 is
It is connected to the step motor 7. Note that 27 is a control signal for switching the switch 24. R above
OM21, PWM circuit 22, and switch 24 constitute a control circuit of the present invention.

The step motor 7 moves the carriage 3 to a target position by a step drive circuit 23 that receives a direction signal 26 and a step signal 25 from an external controller.

Thereafter, the switch 24 is switched by the control signal 27, and the step motor 7 is driven so that the magnetic head 4 on the carriage accurately follows the target data track based on the eccentricity information stored in the memory 18. At this time, the eccentricity information stored in the memory 18 is based on the rotation synchronization clock signal 19 synchronized with the rotation of the disk medium 2.
The signal is read out by the ROM 21 and converted into the drive current level of each phase for the position within one step of the two-phase step motor 7. This situation will be explained with reference to FIG. 3(b).

FIG. 3(b) is a diagram showing the current value of each phase with respect to the position of the step motor 7. Reference numbers 31 and 3 in the diagram
2 indicates the A-phase and B-phase currents, respectively. Also,
The point indicated by reference number 33 is the stopping point when the step motor 7 is operated in steps.
The interval corresponds to the pitch of the step motor 7. Now, if the step motor 7 is stopped at any stop point indicated by reference numeral 33, change the drive current of each phase around that stop point while maintaining the relationship between the position and current shown in the figure. If so, linear operation can be performed within one pitch.

The explanation will be given again by returning to FIG. 3(a). After the eccentricity information is converted into a signal level corresponding to the current value of each phase by the ROM 21, the step motor 7 is driven by pulse width modulation by the PWM circuit 22 via the switch 24. In this way, the magnetic head 4 mounted on the carriage 3 can accurately position and follow the target data track even if the eccentricity is within one pitch.

As explained above, according to this embodiment, by having two servo tracks, the magnetic head can be positioned more accurately on all data tracks than in the case of one servo track. can.

Furthermore, since the device can use a step motor that has been used conventionally, there is no need for an external position sensor, etc., and high track density can be realized at low cost. Furthermore, the servo tracks can be easily recorded when initializing a disk, and a special machine for recording servo tracks is not required, and conventional types of disks can be used as they are.

〔Effect of the invention〕

As explained above, according to the present invention, the magnetic head is linearly moved using the eccentricity information detected by the servo track closest to the target data track among the plurality of servo tracks recorded on the disk. As a result, even if eccentricity exists, the magnetic head can be accurately positioned for all data tracks.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing details of the position error detection circuit, Fig. 3(a) is a block diagram showing details of the drive circuit, Fig. 3(b) ) is a diagram showing phase currents for linearly controlling a step motor. l ・・・・・・・・・ Spindle motor 2 ・・・
・・・・・・ Disc medium 3 ・・・・・・・・・
Carriage 4 ...... Magnetic head 5 ...... Position error detection circuit 6 ...
...... Drive circuit 7 ...... Step motor 11 ...
・・・・・・ Servo track 18 ・・・・・・
...Memory agent Patent attorney Yoshiyuki Iwasa 5 Error detection [Figure 1, Figure 2 (a), Figure 3]

Claims (1)

[Claims] (1) A disk-shaped recording medium provided with concentric data tracks and a plurality of servo tracks and rotated by a drive device, and a transducer for recording and reproducing data are placed in a predetermined radial direction of the recording medium. a step motor that moves step by step by pitch; and a position error that detects a relative positional deviation between the servo track and the transducer and outputs a position error signal when the transducer is located at a position corresponding to the servo track. a detection circuit, and a servo track closest to the target data track in synchronization with the rotation of the recording medium before the transducer records and reproduces data on the target data track for recording and reproduction.
a memory for recording the positional error signal corresponding to the rotation; and a memory for recording the positional error signal corresponding to the rotation, and the transducer is configured to move within the predetermined pitch according to the positional error signal stored in the memory when the transducer records and reproduces data with respect to the target data track. and a control circuit that controls the step motor so that the step motor is continuously moved.