JPS6247883A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To attain the accurate positioning of a magnetic head to a data track with low cost by making use of the information on the eccentricity detected out of the servo track recorded at the most circumference of a disk to shift the magnetic head. CONSTITUTION:When a disk medium 2 is set into a disk device, a magnetic head 4 is positioned at the most outer circumference. Then the head 4 reads the servo track recorded at the most outer circumference of the medium 2 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 6 by an amount equivalent to one round in synchronizing with the revolution of the medium 2. Then the head 4 is continuously to the desired data tracks by a step motor 7 within a prescribed pitch and positioned there. In such a way, the high track density is attained with low cost and without using any external position sensor, etc.

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 out 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 an eccentric data track 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 servo track on the outermost circumference and rotated by a drive device, and a transducer for recording and reproducing data on the recording medium. a step motor that moves the transducer stepwise by a predetermined pitch in a radial direction; and detecting a relative positional deviation between the servo track and the transducer when the transducer is located at a position corresponding to the servo track. a position error detection circuit that outputs a position error signal; and a position error detection circuit that stores the position error signal for one rotation in synchronization with the rotation of the recording medium before the transducer records and reproduces data on the data track. a memory, and the transducer is configured to move continuously within the predetermined pitch according to a position error signal stored in the memory when the transducer records and reproduces data on the data track. and a control circuit for controlling the step motor.

[Effect]

Next, the present invention will be explained in detail. A disk-shaped recording medium provided with concentric data tracks and a servo track on its outermost periphery 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. Furthermore, since the servo track and the data track are provided concentrically, the relative positional misalignment between the servo track and the transducer can be considered to be the same as the relative positional misalignment between the data track and the transducer. .

Therefore, before the transducer records or reproduces data on the data track, the position error signal for one rotation is stored in the memory in synchronization with the rotation of the recording medium, and the transducer reads the data on the data track. When recording and reproducing, if the step motor is controlled according to the stored position error signal and the transducer is moved continuously, that is, linearly, within the above-mentioned predetermined pitch, the transducer can be moved to the data track. Can be positioned accurately.

〔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. magnetic head 4
A position error detection circuit 5 is connected to the position error detection circuit 5, and the position error detection circuit 5 is connected to a step motor 7 via a drive circuit 6.

When the disk medium 2 is installed in the floppy disk device, the magnetic head 4 is positioned to the outermost circumference by the step motor 7, and the magnetic head 4 tracks the servo track recorded on the outermost circumference of the disk medium 2, as will be explained later. 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 for one revolution in synchronization with the rotation of the disk medium 2 rotated by the spindle motor 1. 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 and positioned by the step motor to the target data track. 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 and the eccentricity of the data track can be considered to be the same in frequency and quantity, the step motor 7 is linearly operated within the positioning pitch by the drive circuit 6 in response to the position error stored in the memory. This allows the magnetic head 4 to be accurately positioned on the data track 7.

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. The position error detection circuit 5 includes a preamplifier 12 to which the magnetic head 4 is connected at the input end. Preamplifier 12
The output terminal of is connected to one input terminal of the differential amplifier 17 via the band pass filter 13 and the envelope detector 15, and is connected to the other input terminal of the differential amplifier 17 via the band pass filter 14 and the envelope detector 16. is connected to the input end of the The output terminal of the differential amplifier 17 is connected to the memory 18 of the drive circuit 6. In addition, memo 1
On month 8, a rotation synchronization clock signal 19 is input.

The outermost circumference of the disk medium 2 has two different frequencies (
A servo track 11 is provided in which servo tracks 11 (f+, f2) are recorded adjacently and concentrically. As described above, when the disk medium 2 is loaded, the magnetic head 4 is positioned at the outermost periphery and then at the center of the servo track 11. Therefore, the magnetic head 4 reads out signals of two different frequencies, amplifies them with the preamplifier 12, and outputs them to the bandpass filters 13 and 14. The passing frequencies of the band-pass filters 13 and 14 correspond to two different frequencies (f, f2) of the servo track 11, respectively, and the band-pass filters 13 and 14 each correspond to two different frequencies (f, f2) of the servo track 11.
Different frequencies within the servo track 11 are separated and output. That is, if the magnetic head 4 is offset to either side with respect to the center of the servo track 11, the output signal of one corresponding frequency will become large and the output signal of the other frequency will become 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 calculates the difference between the outputs of envelope detectors 15 and 16. By doing so, the output of the differential amplifier 17 will show a signal proportional to the positional error of the magnetic head 4 with respect to the servo track 11.

The eccentricity of the disk medium 2 can be detected by storing the position error signal detected in this manner for one rotation in the memo January 8 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 to, accurate tracking becomes possible.

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

The drive circuit 6 includes the memory 18 described above. The memory 18 is connected to a switch 24 via a read only memory (ROM) 21 and a pulse width modulation circuit (PWM circuit) 22.
is connected to the input end of the Further, a step signal 25 and a direction signal 26 are input from an external controller (not shown).
The step drive circuit 23 supplied with the switch 240
Connected to the input end. The output end of the switch 24 is connected to the step motor 7. Note that 27 is a control signal for switching the switch 24. The above RO
M21, 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 according to the eccentricity information stored in the memory 18. At this time, the eccentricity information stored in the memo January 8 is 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 the reference number 33 is the stopping point when the step motor 7 is operated in steps, and the point indicated by the reference number 33
The interval is equivalent to the pitch of the step motor 7. If the step motor 7 is now stopped at a stop point indicated by reference numeral 33, the drive current of each phase is changed around that stop point while maintaining the relationship between the position and current shown in the figure. By doing 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, since a conventionally used step motor can be used, an external position sensor or the like is not required, and a high track density can be realized at low cost. Furthermore, the servo tracks can be easily recorded when initializing the disk, and a conventional type disk can be used as is without the need for a special machine for recording servo tracks.

〔Effect of the invention〕

As explained above, according to the present invention, by linearly moving the magnetic head using eccentricity information detected by the servo track recorded on the outermost circumference of the disk,
Even if eccentricity exists, the magnetic head can be accurately positioned with respect to the data track.

[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 that linearly control a step motor. 1 ・・・・・・・・・ Spindle motor 2 ・・・
・・・・・・ Disc medium 3 ・・・・・・・・・
Carriage 4 ...... Magnetic head 5 ...... Position error detection circuit 6 ...
... Drive circuit 7 ... River Step morph 11 ... Servo track 18
・・・・・・・・・ Memory agent Patent attorney Yoshiyuki Iwasa Figure 1 Figure 2

Claims (1)

[Claims] (1) A disk-shaped recording medium provided with concentric data tracks and a servo track on the outermost circumference and rotated by a drive device, and a transducer for recording and reproducing data in the radial direction of the recording medium. a step motor that moves stepwise by a predetermined pitch; and a position 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. an error detection circuit; a memory that stores the position error signal for one rotation in synchronization with the rotation of the recording medium before the transducer records and reproduces data on the data track; and a control circuit that controls the step motor so that the transducer is continuously moved within the predetermined pitch according to the position error signal stored in the memory when recording and reproducing data. Magnetic disk device.