JPH087964B2 - Reference signal writing device - Google Patents

Description

The present invention relates to a reference signal writing device, and more particularly to a servo signal writing device for writing a head positioning servo signal of a magnetic disk device, when writing a servo signal. The present invention relates to a reference signal writing device for writing a reference clock that is a reference for the timing of writing to the.

[Common technology]

Generally, the head positioning servo signal written in the magnetic disk device must be a signal which is perfectly aligned along the radial direction from the disk center. A non-reference timing signal is written, and a servo signal is written based on this reference signal. The reference signal writing device for writing the reference timing signal writes the reference signal based on the first write / read head for writing one signal per turn and the read signal of the first write / read head. It is configured to include a second write / read head.

[Conventional technology]

A conventional reference signal writing device has a first write / read head for writing / reading one signal per turn and a seamless signal for one turn based on an output signal of the first write / read head. A seam judging circuit for judging whether or not a predetermined number of pulses have been written, an oscillator circuit for increasing or decreasing the oscillation frequency according to the judgment result of the seam judging circuit, and a signal obtained by dividing the output signal of the oscillator circuit into n stages. And a second write / read head for writing.

Next, a conventional reference signal writing device will be described in detail with reference to the drawings.

FIG. 3 is a block diagram showing an example of a conventional reference signal writing device.

The reference signal writing apparatus shown in FIG. 3 includes a first write control circuit 53 for generating a signal to be written by the first head 51 and a pulse writing circuit for shaping the signal read from the first head 51 into a pulse waveform. A counter that counts the number of output pulses of the voltage control oscillation circuit 55 based on the output signals of the shaping circuit 54 and the pulse shaping circuit 54.
56, a comparator 57 that compares the value of the counter 56 with the value of the pulse number setting value 58, an up / down counter 59 that increases or decreases the count value by the output signal of the comparator 57, and a value of the up / down counter 59. Outputs the logical product of the D / A converter 60 that converts the analog value and applies the control voltage to the voltage controlled oscillation circuit 55, and the equivalent output signal of the comparator 57 and the signal obtained by inverting the output pulse of the voltage controlled oscillation circuit 55. Gate 61, the output of the gate 61 enters the D input terminal and the output of the pulse shaping circuit 54 enters the clock input terminal, and the frequency divider 63 divides the output pulse of the voltage controlled oscillator circuit 55. And the second output signal of the frequency divider 63 is transmitted to the second head 65 only when the output signal of the D type flip-flop 62 is in the active state.
And a write control circuit 64 of.

Here, the counter 56, the comparator 57, the pulse number set value 58, the gate 61, and the D type flip-flop 62 constitute a joint determination circuit.

The operation will be described in order according to the timing chart of FIG.

When an index write command is given to the write control circuit 53, the head 51 writes one index signal on the disk plate once per revolution, and the index signal a is output to the output of the pulse shaping circuit 54. Then, when the reference signal write signal is applied to the D type flip-flop 62, the output reference signal write control signal f becomes active, and the output of the frequency divider 63 is transmitted to the head 65 through the write control circuit 64. . Here, the counter 56 counts the number of output pulses of the voltage controlled oscillation circuit 55 during one cycle T of the index signal a, and the comparator 57 compares the counted value and the pulse number set value 58 during the next rotation cycle. If the compared counter value is less than the pulse number setting value, the comparator
Up / down counter 59 D / A converter 6 by 57 output signal
Through 0, the oscillation frequency of the voltage controlled oscillator circuit 55 is increased, and in the opposite case, the oscillation frequency is decreased. The pulse number set value 58 is a value obtained by multiplying the number of write pulses required during one rotation of the disk by N. N is a denominator of the frequency division ratio 1 / N of the frequency divider 63. If the counter value is equal to the pulse number set value, the equivalent output signal d is output from the comparator 57, and the logical product f of the output inversion pulse c of the voltage controlled oscillation circuit 55 and the equivalent output signal d is in the active state. When the index signal a rises in the meantime, the output reference signal write control signal f of the D type flip-flop 62 becomes inactive, and the operation of writing the reference signal by the head 65 ends. At this time, if the duty of the output pulse of the voltage controlled oscillator is 50%, the seam accuracy of the reference signal immediately before the index is 1/2 of the oscillation cycle of the voltage controlled oscillator 55. By increasing the frequency, it is possible to tighten the permissible joint value and improve the joint accuracy.

[Problems to be solved by the invention]

The above-mentioned conventional reference signal writing device can be realized by increasing the oscillation frequency of the oscillation circuit in order to improve the accuracy of the seams of the reference signals. Since the probability that the leading edge of the index signal falls within the seam allowable value is reduced, there is a drawback that the reference signal writing time becomes long. Also,
Whether or not the leading edge of the index signal falls within the permissible value of the seam is a problem of probability, and there is a drawback that the writing time greatly varies.

[Means for solving problems]

The reference signal writing device of the present invention includes a first write / read head for writing one signal per turn, and a predetermined number of pulses for one turn based on the read signal of the first write / read head. A write pulse number determination circuit for determining whether or not a number has been written, an oscillation circuit for increasing or decreasing the oscillation frequency based on the determination result of the write pulse number determination circuit, and a second output circuit for writing the output signal of the oscillation circuit. The time interval t between the signal immediately before and after the read signal of the first write / read head in the read signal train of the write / read head and the second write / read head is measured. It is configured to include a seam interval measurement circuit and a time distribution circuit that distributes the measurement time t for every minute time Δt based on the measurement result of the seam space measurement circuit.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

 FIG. 1 is a block diagram showing an embodiment of the present invention.

The reference signal writing device shown in FIG. 1 includes an index pattern generation circuit 14 for sending an index write signal to a write / read head 11 through a selection circuit 13 and a write / read circuit 12.
A pulse shaping circuit 15 that shapes the signal read from the write / read head 11 into a pulse waveform, and a counter 17 that counts the number of output pulses of the voltage controlled oscillation circuit 16 based on the output signal of the pulse shaping circuit 15. Counter 17 value and pulse number setting value
A comparator 18 for comparing the value of 19 and an up / down counter 20 whose count value is increased or decreased by the output signal of the comparator 18,
A D / A converter 21 for converting the value of the up / down counter 20 into an analog value and applying a control voltage to the voltage controlled oscillator circuit 16,
The equivalent output signal of the comparator 18 enters the D input terminal and the output of the pulse shaping circuit 15 enters the clock input terminal. The D type flip-flop 22 and the voltage controlled oscillator circuit only when the output signal of the D type flip-flop 22 is in the active state. A write control circuit 23 for transmitting the 16 output signals to the write / read head 24,
A pulse shaping circuit 26 that shapes the signal read from the writing / reading head through the writing / reading circuit 25 into a pulse waveform, and a pulse shaping circuit 15 of the pulse train output from the pulse shaping circuit 26.
The output pulse train of the pulse interval shaping circuit 26 that counts the time interval between the immediately preceding pulse and the immediately following pulse of the output index signal of, and the output pulse train of the pulse shaping circuit 26 is counted. A block count circuit 28 that divides into blocks and a block count circuit that receives the pulse train of the pulse shaping circuit 26 as an input
A delay circuit 29 that delays the pulse train for each block according to the output signal of 28 and outputs the delayed pulse train to the selection circuit 13 is configured.
The counter 17, the comparator 18, the pulse number set value 19, and the D type flip-flop 22 constitute a write pulse number determination circuit,
The block count circuit 28 and the delay circuit 29 form a time distribution circuit.

The operation will be described in order according to the timing chart of FIG.

When the index write command is given to the index pattern generation circuit 14 after the selection signal of the selection circuit 13 is set to the index writing state, the head 11 writes one index number per one turn on the disk plate and outputs it to the output of the pulse shaping circuit 15. Outputs the index signal a. Subsequently, when a pseudo reference signal write command is given to the D type flip-flop, the output pseudo reference signal write control signal d becomes active, and the output pulse of the voltage controlled oscillator circuit 16 outputs the write control circuit 23.
Through the write / read head 24. Here one cycle T
While the counter 17 counts the number of output pulses of the voltage controlled oscillator circuit 16, the comparator 18 compares the calculated value with the pulse number setting value 19 during the next rotation cycle, and the count value is smaller than the pulse number setting value. In the case of 1, the output signal of the comparator 18 increases the voltage controlled oscillation circuit 16 and the oscillation frequency through the up / down counter 20 and the D / A converter 21, and in the opposite case, the oscillation frequency is decreased. The pulse number set value 19 is a value obtained by adding 1 to the write pulse number n required during one rotation of the disc.

If the counter value and the set pulse number value are equal and the equivalent output signal c from the comparator 18 is active and the index signal a rises, the output pseudo reference signal write control signal d of the D type flip-flop 22 becomes inactive. The writing operation of the pseudo reference signal by the read / write head 24 is completed.

Next, in the pulse train e of the pseudo reference signal read by the write / read head 24, the pulse immediately before the rising edge of the index signal a, that is, the rising edge of the (n + 1) th pulse counted from the index, rises from the rising edge of the index signal a. The seam interval measuring circuit 27 measures the time interval immediately after the pulse, that is, the time interval until the rise of the first pulse. Here, the pulse train for one round is divided into m blocks, the joint time interval t is divided into a minute time Δt, and between the blocks,
An operation of setting the joint time interval t to zero for the entire circumference by distributing and inserting the minute time Δt and delaying each block will be described.

The block counter circuit 28 divides the pulse train for one round into m blocks while counting the pulse train of the pseudo reference signal, and outputs a delay time switching signal f for switching the delay time for each block to the delay circuit 29. . The delay circuit 29 receives the pseudo reference signal pulse train e as an input, and sequentially applies the delay time Δt to the pulse train e for each block in accordance with the delay time switching signal f from the block count circuit 28.

As a result, as shown in the delay circuit output signal g, the delay time of the first block from the index is 0, the delay time of the second block is Δt, and the delay time of the i-th block is (i-1 ) · Δt, and finally m-th
The delay time of the second block is (m−1) · Δt. Here, if Δt is set to be (m−1) · Δt = t, the delay time in this final (m-th) block becomes equal to the seam time interval t. That is, the last pulse of the final (mth) block is the nth pulse counted from the index. In FIG. 2, the delay time (i−1) · Δt in the i-th block is intentionally drawn larger than the joint time interval t in order to make the drawing easy to see. Actually, since i ≦ m, (i−1) · Δt ≦ (m−
1) · Δt, that is, (i−1) · Δt ≦ t. Therefore, after the selection signal of the selection circuit 13 is set to the delay circuit output write state, the output signal g of the delay circuit 29 is output, so that the write / read head has a seam time of 0 and the number of pulses required for one round is n. The reference signal of is written. An interval difference of Δt between the blocks and the pulse intervals of the other pulse trains occurs, but there is no practical problem by reducing Δt.

〔The invention's effect〕

The reference signal writing apparatus according to the present invention requires a pulse width of the oscillation circuit output of a high frequency that generates a pulse number much larger than the pulse number required for one round of the disk, instead of setting the pulse width of the output as the seam allowable value. Has an oscillation circuit that generates almost the same number of pulses (the required number of pulses + 1)
After writing the individual pulses, the seam time is measured, and the reference signal is written by shifting the time so that the time is 0, whereby the reference signal writing time can be significantly shortened. If the fluctuation of the disk rotation speed is the same, the probability of writing the preset number of pulses of the low-frequency pulse oscillation output is much higher than the certainty that the rise of the index will be included in the high-frequency pulse width, and the seam correction This is because the pulse can be distributed in a short time in order to perform. The rate of dependence on the probability is smaller than that of the writing device due to the rise of the index within the narrow pulse width, and the writing time is constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an operation timing chart of the reference signal writing device shown in FIG. 1, FIG. 3 is a block diagram showing an example of the prior art, and FIG. FIG. 4 is an operation timing chart of FIG. 11 ... Writing / reading head, 12 ... Writing / reading circuit, 13 ...
… Selection circuit, 14 …… Index pattern generation, 15 ……
Pulse shaping circuit, 16 …… Voltage controlled oscillator circuit, 17 …… Counter, 18 …… Comparator, 19 …… Pulse number setting value, 20 …… Up-down counter, 21 …… D / A converter, 22 …… D type flip-flop, 23 ... Write control circuit, 24 ... Write / read head, 25 ... Write / read circuit, 26 ... Pulse shaping circuit, 27 ... Seam interval measuring circuit, 28 ... Block counter circuit , 29 ... Delay circuit, 51 ... Write / read head, 52 ...
… Write / read circuit, 53 …… Write control circuit, 54 …… Pulse shaping circuit, 55 …… Voltage controlled oscillator circuit, 56 …… Counter, 57
…… Comparator, 58 …… Pulse number set value, 59 …… Up / down counter, 60 …… D / A converter, 61 …… Gate, 62 ……
D-type flip-flop, 63 ... Divider, 64 ... Write control circuit, 65 ... Write / read head.

Claims (1)

[Claims] 1. A first write for writing one signal per revolution.
A read head, a write pulse number determination circuit for determining whether or not a predetermined number of pulses have been written in one round based on a read signal from the first write / read head, and the write pulse number determination An oscillation circuit that increases / decreases the oscillation frequency according to the determination result of the circuit, a second write / read head that writes an output signal of the oscillation circuit, and a read signal string of the second write / read head 1. A seam interval measuring circuit for measuring a time interval t between a signal immediately before and a signal immediately after the read signal of the write / read head of No. 1, and the measuring time t over one round based on the measurement result of the seam interval measuring circuit. A reference signal writing device, comprising: a time distribution circuit for distributing every minute time Δt.