JPS63872A - Servo writing circuit for magnetic recorder - Google Patents

Abstract

PURPOSE:To improve the accuracy of the positioning of a head, by selecting a write pattern, and the frequency of a servo write circuit to write servo information, corresponding to the position of a cylinder. CONSTITUTION:A clock signal is inputted to a counter 23 through a frequency division circuit 22, and counting is started from a value set by a counter 27, and it is outputted to a selector 24. The selector 24 outputs the content of a bit selected by the output value of the counter 23, out of the values set by a counter 28. Also, the output data of the selector 24 is exclusively OR-ed with the output of the circuit 22, and is synchronized by an FF25, and supplied to a magnetic recorder 31 as a servo information pattern, through a modulator 26. Therefore, the pattern can be set by the counters 27 and 28, corresponding to whether the cylinder is positioned at the inner peripheral side, or an outer peripheral side. In such way, it is possible to perform the positioning of the head with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo write circuit for writing servo information in a magnetic recording device used as a large-capacity external storage device in a computer or the like.

[Conventional technology]

A hard disk device is one of the magnetic recording devices used as a large-capacity external storage device in computers and the like. In this device, a read/write head is arranged opposite the If2 surface of a hard disk plate which rotates at a high speed and constant speed for magnetic recording. A plurality of tracks of magnetic storage trunks of a predetermined width are arranged concentrically on the surface of the hard disk board. Then, the head is caused to seek to the commanded track position, and the data in that track is read or written.

In such a hard disk device,...

The positioning of the tracks on the tracks is based on servo information recorded on each track.

In other words, each track is divided into inner and outer parts with the track's center line as the boundary, and servo data patterns are written on the inner and outer sides respectively, and when positioning the head to a specified track, the servo data pattern for that track is written. Read out the data pattern, obtain this as the output voltage of the servo information, know the position of the head on the track from this, control the head so that it is centered on the track, and prevent off-track. suppress.

In other words, this type of device uses a servo write circuit that writes servo information for head positioning, and thereby writes servo information alternately at predetermined intervals on the inner and outer circumferential sides of the trunk in each cylinder. I am trying to write. The pattern and frequency to be written are constant, and by reading the servo information on the inner and outer sides at the same time, an output voltage corresponding to the frequency component of the servo information is obtained, and the head is adjusted so that this becomes a predetermined value. Adjust and control the position.

If the head position deviates even slightly from the center line of the track to be positioned, the output voltage of the head will change based on servo information reading, so center positioning can be achieved by adjusting and controlling the head position based on this.

Specifically, the servo write circuit consists of 1 as shown in Figure 6.
An oscillation circuit 1 using a crystal oscillator of approximately 0 MHz, a frequency divider circuit 2 that divides the frequency of the clock signal oscillated by this oscillation circuit 1, and a driver circuit 3 that amplifies the output of this frequency divider circuit 2.
and is configured to generate servo data based on a constant frequency clock signal. Then, this servo data is given to the magnetic recording device 4 (with lη configuration).

As shown in FIG. 7, on the magnetic recording device 4 side, after erasing all cylinders of the disk, the servo data received from the servo write circuit is written as servo information on the inner and outer sides of the trunk, and then the servo information is It is checked whether the data was written correctly, and if the writing is defective, the data is erased again and the above writing is performed again. If the servo information has been written correctly, it is checked whether writing has been completed for all cylinders, and if not, the above writing is performed for the next cylinder. Finish the work when medium writing has been completed for all cylinders. In this way, conventionally, servo data based on a clock signal of a constant frequency was written and used as servo information.

[Problem that the invention seeks to solve]

By the way, the above-mentioned trunk is arranged so that the cylinder position is concentric with the disk plate, and the disk plate is rotated at a constant speed, so the cylinder position is either on the inner track or on the outer track. The linear velocity (circumferential velocity) differs depending on whether it is a track or not.

Therefore, in the case of a constant servo pattern, the output voltage of servo information will be lower on tracks at inner cylinder positions where the linear velocity is lower than on tracks at outer cylinder positions, and as described above. When positioning the head based on the output voltage value of the servo information, there is a drawback that the positioning accuracy becomes low.

Therefore, the purpose of this invention is to provide a servo write circuit for writing servo information so that the writing pattern and frequency can be selected so that writing can be performed by selecting this according to the cylinder position. To provide a servo write circuit for a magnetic storage device, which can make the reading output voltage of servo information almost constant even in a positional trunk, and can perform head positioning with high precision.

[Means for solving problems]

In order to solve the above problems, the present invention is configured as follows. That is, information is written in a track at each cylinder position on the magnetic disk plate, and servo information is recorded for positioning the reading head on the track, and this is read by the head and the head position is controlled based on the output voltage. As a means for writing the servo information of the magnetic recording device, a reference signal generating means for generating a reference clock signal, a holding means for holding a thinning condition, and a thinning means for holding the generated reference clock signal. A data generating means that thins out a data string of a desired data pattern or frequency according to conditions, and generates data that is denser at a position where the linear velocity is low and data that is denser at a position where the linear velocity is high depending on the cylinder position of the magnetic disk plate. The magnetic recording apparatus is constructed by providing a control means for giving a set value to the holding means for holding the data so as to obtain coarse data, and for giving the data generated by the data generating means to the magnetic recording device as servo data for recording.

[For production]

This device having such a configuration thins out the reference clock signal to meet the thinning conditions held by the holding means to create an arbitrary data pattern or a data string of an arbitrary frequency. This is then used for writing as servo data. The control means gives a set value to the holding means so as to generate dense data at positions where the linear velocity is low and coarse data at positions where the linear velocity is high, and causes the holding means to hold the data according to the cylinder position of the magnetic disk plate. As a result,
The data generating means generates dense data at positions where the linear velocity is low, and coarse data at positions where the linear velocity is high, depending on the cylinder position of the magnetic disk plate. This data is given to the magnetic recording device as servo data and recorded as servo information.

Therefore, the output voltage of the head when reading servo information is the same everywhere regardless of the cylinder position on the magnetic disk plate. That is, in the present invention, since it is possible to select, output and write a predetermined output voltage according to the linear velocity of the track, it is possible to read and write servo information regardless of the cylinder position of the track. It can be made almost constant, and the head can be positioned with high precision. Therefore, the drawback that the output voltage of servo information decreases at the inner circumferential cylinder position, which is the case with the conventional art, is eliminated.

In the present invention, the servo information readout output voltage is
The same output voltage can be obtained at both the inner cylinder position and the outer cylinder position, so no matter where the head is located, the amount of off-track is proportional to the output voltage of the servo information, so position correction is possible. This makes it possible to easily perform head positioning with high precision.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a system block diagram showing the configuration of this device, and FIG. 2 is a flow chart for explaining the operation of this device.

In FIG. 1, 20 is a servo write circuit, and this servo write circuit 20 includes a clock generator 21 that generates a clock signal of a predetermined frequency, and a frequency dividing circuit using a flip-flop to divide this clock signal into 1/2. 22, for example, a 4-bit counter 23 that counts this frequency-divided clock signal, receives the output of this counter 23 at its corresponding input terminals (A, ~D), and also receives the outputs of these input terminals (A, ~D) A selector 24 outputs a human input signal from a predetermined input terminal (A, to D) determined by an external selection input to an output terminal Y, and outputs the output of this output terminal Y in synchronization with the output of the clock generator 21. A flip-flop 25, a modulator 2B that modulates and outputs the output of the flip-flop 25, and a counter 27 used as a setting device that is set to a predetermined value when receiving a clear signal from the outside and outputs this set value. and a counter 28, a driver 29 that amplifies the modulated output and supplies it to the magnetic recording device, and an XOR circuit 30 that takes an exclusive OR. 31 is a magnetic recording device that receives data from the servo write circuit 20 and writes the data on the disk as servo information.

Note that counters 23, 27, and 28 are model number L516.
3 integrated circuit, and selector 24 has model number L S
A 1η fabrication example is shown using 151 integrated circuits.

1 0 MH obtained from the clock generator 21
The frequency of the clock signal z is divided into 5 MHz by the frequency dividing circuit 22. Then, this frequency-divided clock signal is given to the counter 23, and the clock signal given by the counter 23 is counted. The counter 23 counts the value set by the counter 27 as an initial value, and its output is given to the selector 24 as a selection signal.

Here, assuming that the value of the counter 23 initially set by the counter 27 is "1", the output of the counter 23 that counts the frequency-divided clock signal is QA, 08 in (C) of FIG. %QC%Qo, and if QASQB and QC are used as select data, the select data will be counted up sequentially from "1" to "7". Selector 2
4 to the corresponding input terminals ASB and C. That is, the output of QA of the counter 23 is applied to the terminal A of the selector 24, the output of QB of the counter 23 is applied to the terminal B of the selector 24, the output of Qc of the counter 23 is applied to the terminal C of the selector 24, and the output of the QB of the counter 23 is applied to the terminal C of the selector 24. The output of the QD is inverted and used as its own load signal.

The selector 24 outputs to the terminal Y the contents of the bits selected by the output value of the counter 23 out of the data set by the counter 28. That is, the selector 24
output terminal. , ~D7, the QA of the counter 23 obtained by counting the output clock signal of the clock generator 21 with the output value of the counter 27 as the initial value, ~
Data at the bit position (input terminal) determined by the output of Qc is output to output terminal Y.

Further, the output data of the selector 24 is subjected to an exclusive OR (XOR) with the frequency divided output of the frequency dividing circuit 22 in an XOR circuit 30, and the output is synchronized with a flip-flop 25 and then sent to a modulator 2B modulate, driver 2
9.

Next, the operation of this device having the above configuration will be explained.

10M which is a reference signal from the clock generator 21
A Hz clock signal is output ((A) in FIG. 2), and this signal is applied to a frequency divider circuit 22 including a flip-flop, where the frequency is divided by 1/2 ((B) in FIG. 2). Then, this frequency-divided clock signal is given to the counter 23, which counts the given clock signal, advances the count from the value set by the counter 27, and sends its output to the selector 24. give.

Here, assuming that the initial value of the counter 23 is "1" by the counter 27, the output of the counter 23 that counts the frequency-divided clock signal is QA% Q10 in (C) of FIG. ．． Qc.

It becomes like a QD and is counted up sequentially from "1" to "7".

This output is connected to the corresponding input terminals A1B and C of the selector 24.
is input. That is, the output of QA of the counter 23 is given to the terminal A of the selector 24, the output of Qa of the counter 23 is given to the terminal B of the selector 24, the output of Qc of the counter 23 is given to the terminal C of the selector 24, and the output of the counter 23 is given to the terminal B of the selector 24.
The output of the QD is inverted and input as its own load signal to its load signal input terminal LD. Therefore, when the counter 23 reaches 16, the counter 27
The output value of is zero-coded and the count is advanced to the initial value.

The selector 24 outputs to the terminal Y the contents of the bits selected by the output value of the counter 23 out of the data set by the counter 28. That is, the selector 24
output terminal. , ~D7, Qh of the counter 23 obtained by counting the output clock signal of the clock generator 21 with the output value of the counter 27 as the initial value, ~
Data at the bit position (input terminal) determined by the output of Qc is output to output terminal Y. For example, if the selector 2 is set to hexadecimal number "4E" by the output of the counter 28 (that is, the input terminal Do of the selector 24,
(assuming that parallel data of hexadecimal number "4E" is input to D7), each input terminal Do of the selector 24.

The output of D7 is selected in accordance with the output signal from the counter 23, and becomes an output as shown in FIG. 2(D).

Further, the output data of the selector 24 ((D) in FIG. 2) is subjected to an exclusive OR (XOR) with the frequency-divided output of the frequency dividing circuit 22 ((B) in FIG. 2) in the XOR circuit 30. ((E) in FIG. 2), its output is synchronized by the flip-flop 25 and becomes as shown in (F) in FIG. The thus synchronized output is modulated by the modulator 26 as shown in FIG. 2(G), and then outputted via the driver 29.

Then, it is given to the magnetic recording device 31 as a pattern of servo information.

In this way, according to the present device, the counter 27 and the counter 2
With the setting value 8, a pulse signal having a desired pulse pattern based on the pulse interval of the output clock signal of the frequency dividing circuit 22 can be generated. In the above example, 200 ns,
Pulse intervals of 300 n S% and 400 n s are obtained, and a data pattern can be obtained by combining these.

Therefore, in this device, the magnetic recording device 31 has 20 On.
5% It is assumed that data constituted by a combination of data patterns having time widths of 300 ns and 400 ns is provided.

Of this data pattern, 400 ns single field
If it is 1-, the output voltage of the servo information is affected the most. Therefore, nss
It can be obtained by combining patterns of aoo nS and 400 ns.

Therefore, the counters 27 and 28 are set so that in tracks where the cylinder position is on the outer circumferential side, there is a pattern where there are many 400 ns, and on tracks where the cylinder position is on the inner circumferential side, there is a pattern where there are many 200 ns. The counters 27 and 28 may be set and used so as to be used.

Note that the counter 27 is used to set whether to repeat up to the same upper bit of the counter 28. Therefore, this counter 27 can create a repeating pattern of "1" to "8" bits.

FIG. 3 is a flowchart showing the procedure for writing servo information using the output of the servo write circuit. This control is performed by a control means (not shown).

To write the servo information, as shown in the figure, first erase all cylinders, then write the data to the counter 27.2.
8, then check the cylinder position (number) to determine whether it is larger or smaller than a predetermined value. In other words, check whether it is an inner cylinder or an outer cylinder, and create a pattern corresponding to each cylinder. Counter 27 that can be obtained.
28 setting values are set.

As already mentioned, the inner circumferential side has a pattern with many 200 ns, and the outer circumferential side has a pattern with many 400 ns. Next, generate a data pattern based on this pattern, write it as servo information, and if it has been written correctly, repeat the above operation to write to the next cylinder, and if it has been written to all cylinders, Let's call it an end. If the data is not written correctly, erase that cylinder and write again.

The following is an example, and a pattern may be generated and used in accordance with each cylinder position so that the output voltage obtained when reading servo information is the same at any cylinder position.

FIG. 4 shows another embodiment of the servo write circuit.

This circuit is 80M by clock generator 41)
Iz (7) By generating a clock signal and counting it by the serially connected counter 42.43, 1/2.1/4.1/8 from each output terminal Q A , ~QD of the counter 42.43 .1/1G, 1/32.1/
64. Obtain the output divided into 1/12g.

This output is input manually to the input terminal of the counter 44 in parallel. The counter 44 is similar to the counter 24, and is adapted to receive select data set by a counter 46 whose count can be advanced by an externally applied clock signal. Then, this counter 44 outputs the contents of the bit position (input terminal position) selected by the counter 46 to the terminal Y, and after this output is modulated by the modulator 45,
It outputs to the magnetic recording device 31 via the driver 47.

This circuit has the characteristic that the frequency changes, whereas the circuit shown in FIG. 1 changes the data pattern.

For example, when using an 80kiF1z clock signal, this circuit uses the above frequency division to generate 40MHz, 2
0MHz, lOMHz, 5MHz, 2.5
MH2% 1.25MHz.

You can select frequencies between 0 and 625 MHz.

The flowchart in FIG. 5 shows the control procedure of the control means when writing servo information using the output of the servo write circuit.

This is almost the same as the one in Fig. 3, but the counter 46 is set so that the frequency is low when writing a track where the cylinder position is on the outer circumference side, and from there it moves to the inner cylinder position. Set so that higher frequencies are selected as the frequency increases. In this embodiment, since eight steps can be selected, the frequency can be set for every 76 cylinders.

In this way, the present invention makes it possible to thin out the reference clock signal to create any data pattern or data string of any frequency, and the linear velocity decreases depending on the cylinder position of the magnetic disk plate. Dense data at the position and ↑■ data at the position where the linear velocity is high are generated as servo data and fed to the magnetic recording device to be recorded as servo information.

Therefore, the output voltage of the head when reading servo information is the same regardless of the cylinder position on the magnetic disk plate. Therefore, the drawback that the output voltage of servo information decreases at the inner circumferential cylinder position, which is the case with the conventional art, is eliminated.

In the present invention, the servo information readout output voltage is
Since the same output voltage can be obtained at both the inner cylinder position and the outer cylinder position, the off-track position is proportional to the output voltage of the servo information no matter where the head is located, so position correction is possible. This makes it possible to easily perform head positioning with high precision. Also, depending on customer requirements, servo
It becomes possible to freely select the frequency of the pattern or servo information.

α Effects of the Invention] As detailed above, according to the present invention, it becomes possible to select and set various output data of the servo write circuit for writing servo information, so that the writing pattern or frequency can be selected. Since it is now possible to select and write a predetermined output voltage according to the cylinder position, that is, according to the linear velocity, it is possible to read the servo information and write the output voltage regardless of the cylinder position. It is possible to provide a servo write circuit for a magnetic recording device that can perform almost constant head positioning with high precision.

[Brief explanation of the drawing]

Figure 1 is a system block diagram showing the configuration of this device, Figure 2 is a system block diagram showing the configuration of this device.
The figure is a time chart for explaining the functions of this device, FIG. 3 is a flowchart for explaining the writing procedure of this device, FIG. 4 is a block diagram showing another embodiment of the present invention, and FIG. Figure 4 is a flowchart for explaining the writing procedure when using the circuit, Figure 6 is a diagram showing the main part configuration of a conventional example, and Figure 7 is a flowchart for explaining the procedure for writing servo information. be. 20... Servo write circuit, 21.41... Clock generator, 22... Frequency dividing circuit, 23.27.2
g, 42.43°46...Counter, 24.44.
...Selector, 25...Flip-flop, 26.4
5...Modulator, 29.47...Driver, 3
0...XOR circuit, 31... Magnetic recording device.

Claims (1)

[Claims] Information is written in a track at each cylinder position on the magnetic disk plate, and servo information is recorded for positioning the read head on the track, and this is read by the head to control the head position based on the output voltage. The means for writing the servo information in the magnetic recording device is a reference signal generating means for generating a reference clock signal, a holding means for holding thinning conditions, and the generated reference clock signal corresponds to the thinning conditions held. a data generating means that thins out a data string of a desired data pattern or frequency; and a data generating means that thins out dense data at positions where the linear velocity is low and data which becomes coarse at positions where the linear velocity is high, depending on the cylinder position of the magnetic disk plate. control means for giving a setting value to the holding means so as to obtain the data, and also giving the data generated by the data generating means as servo data to the magnetic recording device for recording. A servo write circuit for a magnetic recording device, characterized in that a servo pattern is changed so that an output voltage is constant.