JPH0323570A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To accurately control the speed of a magnetic head and to quickly position the magnetic head by increasing a speed signal and a target speed signal K-number of times at the time when the distance from the position of the magnetic head to a target position reaches a preliminarily set residual extent of movement in the seek operation. CONSTITUTION:Servo information SI on a disk 1 is read by a magnetic head 3, and the speed signal indicating the movement speed of the magnetic head 3 is generated by a speed signal generating circuit 15, and the speed signal is amplified by gain control means 25 and 26 and is outputted. A central processing unit 13 outputs a speed command value at the time of moving the magnetic head 3 to the target position; and when the distance from the present position of the magnetic head 3 to the target position reaches a preliminarily set residual extent N of movement, the unit 13 increases the speed command value K-number of times (K>1) and outputs a control signal to gain control means 25 and 26. When the control signal is supplied to a gain control means 27, the gain is switched to K-fold gain. Thus, the speed of the magnetic head 3 is accurately controlled to quickly position the magnetic head 3.

Description

[Detailed Description of the Invention] "Fields of Application in Industry 7" Does this invention apply to computer storage devices, etc.? The present invention relates to a magnetic disk device suitable for use in this field.

"Prior Art" Conventionally, in a magnetic disk drive, PID (Proportion
tional Integral Derivative
e) Control. By doing this, the servo head was made to reach the target position.

FIG. 3 is a block diagram showing the configuration of the conventional magnetic disk device described above. In this figure, servo information S1 written in advance on the servo surface of a disk 1 is read by a servo head 3 attached to the tip of a head arm 2. This servo information Sl is shown in FIG. 4(a).
As shown in FIG. R. It consists of Q and Q magnetic patterns, a timing clock for extracting this position information, and servo sync bits necessary to configure the unique pattern. For example, the servo head 3 is at position D shown in FIG. 4(a). If it is in A, B, C, servo head 3
Each waveform read out is as shown in FIG. 4(b). The servo information S[ read by the servo head 3 is represented by the head amplifier 4 and filter 5 shown in FIG.
It is supplied to AC; C6 (auto gain controller) through. The servo information S[ output from the AGC 6 passes through the SYNC separator 7 and the phase detector 8 to the wind pulse generator 9 and the VCO.
(voltage control oscillator) 10. The wind pulse generator 9 is used to select position information and unique patterns from the servo information Sl. Further, the servo information SI is also supplied to the position demodulator 1l, which obtains the position signal of the servo head 3 from the servo information SI.

The unique patterns divided by the wind pulse generator 9 are supplied to a position demodulator 11 and a unique pattern detection circuit 12. The unique pattern detection circuit l2 detects an index or a guard band from the unique pattern and supplies the detected data to the CPU (central processing circuit) I3.

On the other hand, in the Bonochon demodulator 1l, the unique pattern output from the wind pulse generator 9 and the AGC 6
A position signal consisting of N and Q phases having a 90° phase difference is generated based on the servo information S outputted by the servo information S (see FIGS. 5(d) and (e)).

This position signal is supplied to the speed signal generation circuit 15 and the Bonyon signal generation circuit 16. Speed signal generation circuit I5
Then, the speed signal Sv1 is generated based on the position signal. Further, the position signal generation circuit 16 generates a position signal multiplied by four (see FIG. 5(f)). The pulse width of this position signal corresponds to one track of transparency,
The center value corresponds to the center position of each track. This position signal is then converted into digital signals φC and φD.
(Fig. 5 (h), (i)
reference).

Next, a description will be given of the operation of moving the servo head 3 to the target position (target track).

First, when a nook command is input to the CPU 3 as shown in FIG. 5(a), the C P LJ 1 3 outputs the control signal A shown in FIG. 5(b) and enters the position control mode of the track following operation. At the same time as switching the servo control system to the speed control mode that enables the start-up operation (see Fig. 5),
c)) and the speed command value ■''). This speed command value VD is supplied to a DAC (digital-to-analog converter 18) via a latch circuit 17.
At I8, the speed command value VD is converted into a target speed signal SV, which is an analog signal, and this target speed signal S V t is supplied to the summation point 19. Further, the control signal A is supplied to the switching circuit 20, which switches from the bonotion signal generation circuit l6 to the speed signal generation circuit l5. Then, at the addition point 19, a speed signal generation circuit l5
Speed signal Svl and target speed signal Sv output from
A deviation signal based on t is obtained. This deviation signal passes through the phase compensation circuit 21 to the VCM (Voice Coil Motor)
The signal is supplied to the driver 22. Then, the VCM 23 is driven by this VCM driver 22, and the head arm 2
swings, and the servo head 3 moves above the disk 1. When the servo head 3 reaches the target position, the switching circuit 20 is switched to the position signal generation circuit 16 side (see FIGS. 5(b) and 5(c)), and the mode shifts to the position control mode.

``Problem to be Solved by the Invention 1 By the way, in the above-mentioned conventional magnetic disk device, the speed of the servo head decreases as it approaches the target position.
When the target position is finally reached, the speed is reduced to zero.

In this case, the servo head approaches the target position and its moving speed decreases, as shown in FIG. 5(b).
As the speed decreases, it is affected by offset and speed control deteriorates. Furthermore, the DAC that generates the target speed signal is typically 8 bits due to cost considerations. Therefore, the resolution of the target speed signal is only 1/256 of the maximum value, and the smaller the speed command value is, the larger the amount of change per bit of the target speed signal relative to the speed signal becomes. . Therefore, even if the speed signal of the servo head is fed back correctly, accurate speed control will not be possible in the low speed portion where the moving speed approaches zero. As a result, the above-described transfer from the speed control mode to the position control mode is not successful, resulting in a problem that the settling time of the servo head worsens and the access time performance deteriorates.

This invention has been made in view of the above-mentioned problems, and aims to provide a magnetic disk device that enables accurate speed control of a servo head at low speeds and enables high-speed positioning of the servo head. .

"Means for Solving the Problems" In order to solve these problems, the present invention provides a magnetic head that reads servo information on a disk, and a speed signal generator that generates a speed signal indicating the moving speed of the magnetic head. a circuit, a gain control means for amplifying and outputting the speed signal, and a gain control means for outputting a speed command value when moving the magnetic head to the target position, and a gain control means for outputting a speed command value when moving the magnetic head to the target position, and a gain control means for outputting a speed command value when moving the magnetic head to the target position, Preset remaining travel distance MN
a central processing unit that multiplies the speed command value by K (K>1) and outputs a control signal to the gain control means when the speed command value reaches K (K>1); It is characterized in that the gain can be cut from 1 to K times.

"Function" When moving the magnetic head to the target position, the distance between the magnetic head position and the target position is the preset remaining travel distance N.
When the central processing speed reaches K, the central processing speed multiplies the speed command value and outputs a control signal to the gain control means. When this control signal is supplied, the gain control means switches the gain from 1 times to K times, increases the speed signal by K times, and outputs the same.

"Embodiments" Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, parts corresponding to the parts of the conventional example shown in FIG. 3 are given the same reference numerals, and explanations thereof will be omitted.

In this figure, 25 is an amplifier, which has a gain of l times a. Further, 26 is an amplifier, which has a gain of K (K>1) times. The human power terminals of the ANBU 25 and the ANBU 26 are connected in common, and the speed signal generation circuit 1 is connected to these human power terminals.
A speed signal Sv outputted from 5 is supplied. Further, 27 is a switching circuit, which supplies one of the output signals outputted from the amplifiers 25 and 26 to one end of the switching circuit 20 based on the control signal B from the CPU 3.

Next, a seek operation in the above configuration will be explained. First, like the magnetic disk device shown in FIG.
When a seek command is manually inputted to I3, the CPU 13 sends predetermined control signals A and B to each of the switching circuits 20 and 27.
Output. The switching circuit 20 switches from the position signal generation circuit 16 side to the switching circuit 27 side based on the control signal A, and the switching circuit 27 switches from the position signal generation circuit 16 side to the switching circuit 27 side based on the control signal B.
Switches from the 6 side to the Amb 25 side. In this case, the switching circuit 27 is set to the amplifier 2 5 in advance by initial setting or the like.
It may be switched to 01+1. Also, CPUl
3 outputs a speed command value VD (see FIG. 2), and this speed command value VD is converted by a DAC l8 into a target speed signal SV, which is an analogue signal, and then supplied to a summing point l9. On the other hand, the speed signal Sv1 output from the speed signal generation circuit 15 passes through the amplifier 25 and is supplied to the summing point 19 via the switching circuit 27 with the gain unchanged. As a result, this addition point 19 has a speed signal Sv
1 and the target speed signal S V t is obtained.

Then, the servo head 3 moves above the disk 1 at a speed based on the speed deviation, as shown by the solid line in FIG. When the distance between the current position and the target position of the servo head 3 reaches a preset remaining travel distance N (see FIG. 2), the CPU 3 outputs a control signal B to the switching circuit 27. The switching circuit 27 receiving the control signal I3 switches the amplifier 26 having a gain of K times based on the control signal H.
Switch to the side. Further, at the same time as the control signal B shown in L is output, the speed command value VI) is multiplied by K times like the gain of the amplifier 26. By multiplying the speed command value VD from CPU 3 by K in this way, the target speed signal SV. As the dynamic range of
Resolution is improved (see Figure 2) and accurate speed control is achieved. Then, when the servo head 3 reaches the target position, the switching circuit 20 switches to the side of the signal generation circuit 16 based on the control signal A, and the switching circuit 27 switches to the 1x gain based on the control signal B. The switch is made to the side of the amplifier 25 that has the That is, the servo control system shown in FIG. I is switched from the speed control mode to the position control mode.

Note that the speed signal generation circuit 15, the position signal generation circuit 16, the latch circuit I7, and the DAC 18 described above are 1
Even if it is built into two L and SL chips. in this case,}
- A switched capacitor differentiator is suitable for the differentiator (not shown) used in the recording speed signal generation circuit 15. The gain of the switched capacitor differentiator changes when the number of clock cycles l1 for operation of the switched capacitor differentiator is changed. Therefore, if a switched cavantor differentiator is used as the second differentiator, the circuit configuration will be simplified,
Furthermore, a point f is obtained in which the error can be reduced.

"Effects of the Invention" As explained above, according to the present invention, when the distance from the position of the magnetic head to the target position reaches the preset remaining travel distance MN in the nuking operation, the speed signal and the target speed signal are By multiplying by K times, it is possible to accurately control the speed of the magnetic head, and there is an advantage that the magnetic head can be positioned at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of this embodiment, and FIG. 3 shows the configuration of the servo system of a conventional magnetic disk device. FIG. 4 is a waveform diagram of a servo signal for explaining the operation of the magnetic disk device, and FIG. 5 is a timing chart for explaining the conventional operation. Fig. 5 l...disk, 3...servo head (magnetic head), l3...CPLJ (central processing unit d), 15...speed signal generation circuit, 25.26・
...Anobu (gay 7 control path), 27...
Switching circuit (gain control circuit).

Claims (1)

[Claims] A magnetic head that reads servo information on a disk, a speed signal generation circuit that generates a speed signal indicating the moving speed of the magnetic head, a gain control means that amplifies and outputs the speed signal, and a magnetic head that moves the magnetic head to a target position. A speed command value is output when the magnetic head is moved to the target position, and when the distance from the current position of the magnetic head to the target position reaches a preset remaining travel distance N, the speed command value is multiplied by K (K>1). and a central processing unit that outputs a control signal to the gain control means, and the gain control means cuts the gain from 1 to K times when the control signal is supplied. A magnetic disk device characterized by: