JPH11176093A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk device tolerant in variation of the number of rotations of a disk caused by variation of a power source or the like. SOLUTION: This is a magnetic disk device in which track dividing information and reading/writing information are recorded in one track, the reference clock is counted based on the track dividing information, writing is started with a prescribed count value at the time of writing data, and reading is started with another prescribed value at the reading. And, this device has a comparison circuit 10 comparing a period of track driving information recorded in a track with the prescribed value, a delay circuit 8 varying delay quantity corresponding to the compared result, and a writing/reading control circuit 5 counting the reference clock based on track dividing information delayed by the delay circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic disk drive.

[0002]

2. Description of the Related Art The conventional configuration of a conventional magnetic disk drive for performing write / read control is as follows.

FIG. 3 is a diagram showing a conventional configuration, and FIG. 4 is a diagram showing waveforms at various parts in FIG.

[0004] The conventional configuration comprises a magnetic disk 1 for storing and reproducing data, a magnetic head 2 and a read / write circuit 3 for amplifying a read signal from the magnetic head and sending a write current. A data recovery circuit 4 for demodulating the read signal and converting the read signal into read information; a write / read control circuit 5 for receiving a write / read command from the outside to control the write / read operation of the magnetic disk device; It comprises a servo mark detection circuit 6 for detecting a servo mark, and a crystal oscillator 7 for generating a reference clock serving as a control timing clock.

FIG. 4 shows waveforms and timings at main points in FIG. A conventional technique will be described with reference to FIG.

The servo sector is recorded in advance when the magnetic disk drive is manufactured, and cannot perform a recording operation when actually used. Here, a case where four data sectors are included in a servo frame from servo sector to servo sector will be described. In the writing operation, when a servo mark is detected, the control circuit counts a reference clock, and when a predetermined integration number is reached, the control circuit turns on a writing gate signal and starts writing. The time until the first data sector is turned on is Twg1, the time until the second data sector is turned on is Twg2, and similarly Tw.
g3 and Twg4. In a read operation, when a servo mark is detected, the control circuit counts a reference clock,
When the specified integration number is reached, the read gate signal is turned on,
Turns off when predetermined data is read. The time required to turn on the first data sector is Trgl, the time required to turn on the second data sector is Trg2, and similarly Trg3.
Trg4.

[0007]

The above-mentioned prior art has the following problems.

The first problem is that if the rotational speed of the magnetic disk is different between writing and reading, the read gate signal at the position recorded on the recording disk does not turn on properly at the time of reading, and the data can be read correctly. The disadvantage is that there is not.

The reason will be described below. For example, a case where the number of rotations decreases during writing and increases during reading will be described with reference to FIG.

Since the write gate signal is turned on and off by the integration of the reference clock, when recording is performed at a low rotation speed, the data sector is shifted relatively to the servo frame before the rotation speed is normal. . If the data recorded in this way is read out at a high rotation speed,
The read gate signal which is turned on / off by the reference clock is shifted backward relative to the servo frame. As a result, in the subsequent data sector, the read gate signal cannot be turned on at an appropriate recording position, and a read malfunction occurs.

Conversely, the case where the number of rotations is high during writing and low during reading will be described with reference to FIG.

Since the write gate signal is turned on and off by the integration of the reference clock, when recording is performed when the rotation speed is high, the data sector is shifted rearward relative to the servo frame than when the rotation speed is normal. . In this case, interference with the next servo sector occurs, causing a problem that the servo sector is disturbed. In addition, the data recorded in this way
If read at low rotation speed, it will turn on with the reference clock.
The read gate signal to be turned off is shifted relatively forward with respect to the servo frame. As a result, in the subsequent data sector, the read gate signal cannot be turned on at an appropriate recording position, and a read malfunction occurs. There were the above problems.

The second problem is that, in order to solve the first problem, in the prior art, the space between data sectors is made large and the preamble portion of the data sector is made large so that recording is performed even if the position of the read gate changes. We did not deviate from position. In this case, there is a disadvantage that the data efficiency in one round of the track is deteriorated and the capacity of the entire apparatus is reduced.

An object of the present invention is to provide a magnetic disk drive that is resistant to fluctuations in the number of revolutions of the disk due to fluctuations in the power supply. As a result, an object is to reduce the redundant portion between the inter-sector gaps constituting the data sector and increase the capacity.

[0015]

A magnetic disk drive according to the present invention is a magnetic disk drive in which track division information and write / read information are recorded on one track.
The reference clock is counted based on the track division information, and when data is written, writing starts at a predetermined count value, and when reading data, reading is started with another predetermined count value. A comparison circuit that compares the cycle of the divided track division information with a predetermined value, a delay circuit that changes a delay amount according to the comparison result,
A write / read control circuit for counting a reference clock based on the track division information delayed by the delay circuit.

Further, as the track division information, a servo mark which is positioning information recorded on one track may be used.

When the rotation speed of the magnetic disk fluctuates and recording is performed at a low rotation speed and reproduction is performed at a high rotation speed, the delay amount of the delay circuit when recording at a low rotation speed is as follows.
The difference between the cycle of the servo pulse of the servo mark at the low rotation speed and the cycle of the servo pulse of the servo mark at the normal rotation speed may be increased by １ ／.

When the rotation speed of the magnetic disk fluctuates and recording is performed at a low rotation speed and reproduction is performed at a high rotation speed, the delay amount of the delay circuit when reproducing at a high rotation speed is as follows.
The difference between the cycle of the servo pulse of the servo mark at the high rotation speed and the cycle of the servo pulse of the servo mark at the normal rotation speed may be reduced by ２.

When the rotation speed of the magnetic disk fluctuates and recording is performed at a high rotation speed and reproduction is performed at a low rotation speed, the delay amount of the delay circuit when recording at a high rotation speed is as follows.
The difference between the cycle of the servo pulse of the servo mark at the high rotation speed and the cycle of the servo pulse of the servo mark at the normal rotation speed may be reduced by ２.

When the rotation speed of the magnetic disk fluctuates and recording is performed at a high rotation speed and reproduction is performed at a low rotation speed, the delay amount of the delay circuit when reproducing at a low rotation speed is as follows.
The difference between the cycle of the servo pulse of the servo mark at the low rotation speed and the cycle of the servo pulse of the servo mark at the normal rotation speed may be increased by １ ／.

Therefore, a means for detecting a change in the number of rotations is provided, and the control time of the write gate and the read gate is operated in accordance with the increase or decrease, so that the write gate signal and the read gate signal do not deviate from the medium recording position. By doing so, even if a large rotation speed fluctuation occurs, it is possible to prevent the servo sector from being disturbed due to interference with the servo sector or from erroneously reading data. Can be provided.

If the fluctuation in the number of revolutions is not so large, the distance between the data sectors and the distance between the data sector and the servo sector can be reduced, so that more data can be recorded and the magnetic capacity of the recording capacity is increased. A disk device can be provided.

[0023]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a configuration of a magnetic disk device that performs write / read control according to an embodiment of the present invention, and FIG. 2 is a time chart showing waveforms at main points in FIG.

Referring to FIG. 1, the configuration of a magnetic disk drive for performing write / read control according to an embodiment of the present invention includes a magnetic disk 1, a magnetic head 2, and a write / read for performing write / read operations on the magnetic head. A circuit 3, a data demodulation circuit 4 for demodulating the read data and converting it to recorded data, and a higher-level device (not shown)
In response to the write / read control signal j from the host device, the user data for recording received from the host device is modulated into data suitable for recording, sent to the write / read circuit 3 as write data a, and demodulated by the data demodulation circuit 4. The readout data b is sent to the host device, and in response to a write / read control signal received from the host device, a reference is output from the crystal oscillator 7 based on the delayed servo pulse m output from the delay circuit 8 at the time of writing. The clock f is counted, and when a predetermined integrated value is reached, a write gate signal k is sent to the write / read circuit 3. At the time of read, the reference output from the crystal oscillator 7 is based on the delayed servo pulse m output from the delay circuit 8. The clock f is counted, and the read gate signal d is sent to the data double tone circuit 4 when a predetermined integrated value is reached. A look read control circuit 5, detects the servo mark from the read signal l, a servo mark detection circuit 6 for output as a servo pulse e, the reference clock f
, A counter 9 for inputting a servo pulse e and a reference clock f and counting the number of reference clocks between the servo pulses, a count value of the counter 9 and a reference count value n
A comparison circuit 10 that compares the magnitude of the delay control signal r and outputs a delay control signal r corresponding to the difference, and a delay servo pulse m that delays the servo pulse e by a delay amount corresponding to the delay control signal r.
And a delay circuit 8 for outputting the same.

Next, the operation of this embodiment will be described with reference to FIG.

Referring to FIG. 2A, the write and read control timings when the disk rotational speed is normal are four normal rotational speeds. The servo sector in the medium recording information is read from the magnetic head 2,
The signal is amplified by the write / read circuit 3 and then input to the servo mark detection circuit 6, where the servo mark is detected by the servo sector and the servo pulse e is output. The servo pulse e is input to the counter 9. The reference clock f, which is the output of the crystal oscillator, is also input to the counter 9.
The counter 9 counts the reference clock e from the servo pulse e until the next servo pulse, and outputs the counted value to the comparison circuit 10. The comparison circuit 10 compares the count value of the counter 9 with the reference count value n, and outputs the difference value to the delay circuit 8 as a delay control signal r. The reference count value n is
Set the counter output value under normal conditions. Therefore, in a normal situation, the counter output and the reference count n are substantially equal to each other, and the delay control signal r at this time is set to a value corresponding to the difference 0. The amount of delay of the delay circuit 8 at this set value is appropriately about 1/2 of the amount of change in the servo pulse period due to the expected rotation fluctuation. This value is d0. The delayed servo pulse m is a signal delayed by d0 from the servo pulse e.

At the time of writing, the write / read control circuit 5 sets the reference clock f based on the delayed servo pulse m.
And a write gate signal k is generated at a predetermined timing. The first data sector is the time Twg1 'from the delay servo sector, and the second data sector is Twg1'
2 ', the third data sector is generated after Twg3', and the fourth data sector is generated after Twg4 '. These are respectively Twg1 = Twg1 ′ at the time from the servo pulse e.
+ D0, Twg2 = Twg2 '+ d0, Twg3 = Tw
g3 ′ + d0, Twg4 = Twg4 ′ + d0. Each write gate is turned off after a predetermined number of data is written. The blue imprint data is additionally recorded in consideration of a change in the recording position due to a change in the number of revolutions. The state of writing on the magnetic disk is indicated by medium recording information in FIG.

At the time of reading, the write / read control circuit 5 sets the reference clock f based on the delayed servo pulse m.
And a read gate signal d is generated at a predetermined timing. The first data sector is the time Trg1 'from the delay servo sector, and the second data sector is the same as Trg1'.
2 ', the third data sector is generated after Trg3', and the fourth data sector is generated after Trg4 '. These are respectively Trg1 = Trg1 ′ at the time from the servo pulse e.
+ D0, Trg2 = Trg2 ′ + d0, Trg3 = Tr
g3 ′ + d0, Trg4 = Trg4 ′ + d0. The start position of the read gate signal d is turned on at a position delayed from the write gate signal k in consideration of a change in the recording position due to a change in the disk rotation speed. Read gate signal d
Is turned off when the read data has transmitted a predetermined number of data to the write / read control circuit 5.

In a normal rotation speed, as shown in FIG. 2, the read gate signal d is turned on / off substantially at the center of the recording position of the medium, and normal reading is possible.

FIG. 2B shows a case where the rotation speed fluctuates and recording is performed at a low rotation speed and reproduced at a high rotation speed. At a low rotation speed, the cycle of the servo pulse is TsecL1. At this time, the delay amount of the delay circuit 8 is the period T at the time of the normal rotation speed.
It is set to increase by １ ／ of the difference from secN. That is, assuming that d1 = (TseL1−TsecN) / 2, the start positions of the first to fourth write gate signals k are Twg1 + d1, Twg2 + d1, and Twg3, respectively.
+ D1 and Twg4 + d1, and are recorded with a time delay of d1.

Servo pulse e at high rotation speed during reproduction
Is TsecS2. At this time, the delay amount of the delay circuit 8 is set to a value smaller by 1/2 of the difference from the period TsecN at the time of the normal rotation speed. That is, d2 = (Tse
cN-TseS2) / 2, the start positions of the first to fourth read gate signals d are Trg1-d, respectively.
2, Trg2-d2, Trg3-d2, Trg4-d2
Are reproduced earlier by d2. By performing control as described above, the position of the read gate signal d can be prevented from deviating from the medium recording position.

Next, FIG. 2C shows a case where the rotation speed fluctuates and recording is performed at a high rotation speed and reproduction is performed at a low rotation speed. At high rotation speed, the cycle of the servo pulse is TsecS3). At this time, the delay amount of the delay circuit 8 is set to be smaller by half the difference from the period TsecN at the time of the normal rotation speed. That is, d3 = (TsecN-TseS
Assuming that 3) / 2, the start positions of the first to fourth write gate signals k are Twg1-d3 and Twg2-d3, respectively.
d3, Twg3-d3 and Twg4-d3, respectively, and are recorded earlier by d3. Thus, it is possible to prevent the fourth data sector from interfering with the servo sector.

Servo pulse e at low rotation speed during reproduction
Is TsecL4. At this time, the delay amount of the delay circuit 8 is set to a value which is larger by a half of the difference from the cycle TsecN at the time of the normal rotation speed. That is, d4 = (TseL
4-TsecN) / 2, the start positions between the first to fourth read gate signals d are Trg1 + d4, respectively.
Trg2 + d4, Trg3 + d4, Trg4 + d, and are reproduced with a time delay of d4. By performing control as described above, the position of the read gate signal d can be prevented from deviating from the medium recording position.

[0034]

As described above, according to the present invention, a means for detecting a change in the number of revolutions is provided, and the control time of the write gate and the read gate is manipulated in response to the increase or decrease, so that the write gate signal and the read The gate signal is
By avoiding deviation from the recording position of the medium, even if a large fluctuation in the number of rotations occurs, it is possible to prevent the servo sector from being disturbed by interference with the servo sector or from erroneously reading data, thereby improving reliability. There is an effect of providing a magnetic disk device with high performance.

When the rotation speed fluctuation is not so large, the distance between data sectors and the distance between the data sector and the servo sector can be reduced, so that more data can be recorded, and the magnetic capacity of the recording capacity is increased. There is an effect of providing a disk device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a configuration of a magnetic disk device that performs write / read control according to an embodiment of the present invention.

FIG. 2 is a waveform chart showing waveforms at main points in the embodiment of the present invention.

FIG. 3 is a waveform diagram showing waveforms at main points in the related art.

FIG. 4 is a block diagram of a configuration of a magnetic disk device that performs write / read control according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk 2 Magnetic head 3 Write / read circuit 4 Data demodulation circuit 5 Write / read control circuit 6 Servo mark detection circuit 7 Crystal oscillator 8 Delay circuit 9 Counter 10 Comparison circuit

Claims (6)

[Claims] 1. A magnetic disk drive in which track division information and write / read information are recorded on one track, wherein a reference clock is counted based on the track division information, and a predetermined count value is used when data is written. A comparison circuit for comparing a period of track division information recorded in a track with a predetermined value, in a magnetic disk drive that starts writing and starts reading with another predetermined count value during reading, A magnetic disk drive, comprising: a delay circuit that changes a delay amount according to a result of the operation; and a write / read control circuit that counts a reference clock based on track division information delayed by the delay circuit. . 2. The magnetic disk drive according to claim 1, wherein a servo mark as positioning information recorded on one track is used as the track division information. 3. When the rotation speed of the magnetic disk fluctuates and recording is performed at a low rotation speed and reproduction is performed at a high rotation speed, the delay amount of the delay circuit when recording at a low rotation speed is:
2. The magnetic disk drive according to claim 1, wherein a difference between the cycle of the servo pulse of the servo mark at the low rotation speed and the cycle of the servo pulse of the servo mark at the normal rotation speed is increased by half. 4. When the rotational speed of the magnetic disk fluctuates and recording is performed at a low rotational speed and reproduction is performed at a high rotational speed, the delay amount of the delay circuit when reproducing at a high rotational speed is:
2. The magnetic disk drive according to claim 1, wherein the difference between the period of the servo pulse of the servo mark at the high rotation speed and the period of the servo pulse of the servo mark at the normal rotation speed is reduced by half. 5. When the rotation speed of the magnetic disk fluctuates and recording is performed at a high rotation speed and reproduction is performed at a low rotation speed, the delay amount of the delay circuit when recording at a high rotation speed is:
2. The magnetic disk drive according to claim 1, wherein the difference between the period of the servo pulse of the servo mark at the high rotation speed and the period of the servo pulse of the servo mark at the normal rotation speed is reduced by half. 6. When the rotational speed of the magnetic disk fluctuates and recording is performed at a high rotational speed and reproduction is performed at a low rotational speed, the delay amount of the delay circuit when reproducing at a low rotational speed is:
2. The magnetic disk drive according to claim 1, wherein a difference between the cycle of the servo pulse of the servo mark at the low rotation speed and the cycle of the servo pulse of the servo mark at the normal rotation speed is increased by half.