JPH02230568A - Head positioning controller - Google Patents

Abstract

PURPOSE:To prevent phenomenon where the oscillation of a head remains after outputting a positioning completion signal by the resonance of a head mechanism part according to the fast travel of the head occurring by adjusting the output timing of the positioning completion signal corresponding to an oscillation level in the resonance frequency band area of the head mechanism part. CONSTITUTION:When the head 1 is accessed and arrives in the neighborhood of a prescribed position by controlling the driving of the head 1 directing to a targeted track 2 by a control means 3, a control mode switching means 5 switches the means 3 to a control means 4, and the positioning control of the head 1 to the targeted track 2 is performed. After switching at the switching means 5 is completed, the positioning completion signal is outputted from a completion signal output means 6, however, when the oscillation level in the resonance frequency band area of the head mechanism part is detected by an oscillation detecting means 7 at the time of performing the driving control of the head by the control means 3, a timing control means 8 adjusts the output timing of the positioning completion signal from the completion signal output means 6 corresponding to a detected signal level. Thereby, the oscillation of the head can be prevented from remaining after the positioning completion signal is outputted even when the oscillation occurs at the time of performing the position control of the head 1.

Description

[Detailed Description of the Invention] [Summary] When the head is driven toward a target track and the head reaches the vicinity of the target track, the control mode is changed to move the head onto the target track based on the detected position. Regarding a head positioning control device that switches to a position control mode and outputs a positioning completion signal after a predetermined period of time has elapsed since the switching, head vibration occurs after the positioning completion signal is output due to resonance of the head mechanism due to high-speed movement of the head. The purpose of the present invention is to provide a reliable head positioning control device that prevents the phenomenon that remains, and adjusts the output timing of the positioning completion signal according to the vibration level in the resonant frequency band of the head mechanism including the head. It is configured as follows.

[Industrial application field]

The present invention relates to a head positioning control device applied to a disk device, and more specifically, when the head is driven toward a target track and the head reaches the vicinity of the target track, the control mode is The present invention relates to a head positioning control device which switches the position control of the head onto a target track based on a detected position and outputs a positioning completion signal after a predetermined period of time has elapsed since the switch.

[Conventional technology]

Conventionally, this type of head positioning control device has a configuration as shown in FIG. 4, for example.

This positioning control device performs so-called coarse control in which the head is driven steadily to the target 1-rack by controlling its speed, and the position is controlled on the head target track (on-track) based on the detected position. , two types of so-called fine control are realized.

In FIG. 4, 10 is a head, and this head 10
is integrally fixed to the carriage together with another data read/write head 1, and is exclusively used for seek control facing the disk on which servo information has been written. A position signal generating circuit 11 demodulates a search signal from the head 10 into a position signal, and generates a positive or negative voltage depending on the amount of positional deviation from the rack center. Reference numeral 12 denotes a speed signal generation circuit that generates a speed signal (■) of the head 10 based on changes in the position signal from the position signal generation circuit 11, and 13 a target speed corresponding to a predetermined target speed according to the distance to the target track. A target speed generating circuit 14 outputs a signal vO, and a speed error generating circuit 14 outputs a difference signal between the speed signal V from the speed signal generating circuit 12 and the target speed signal ``o'' from the target speed generating circuit 13. ” The target speed signal vO created by the target speed creation circuit 13 is
The value becomes smaller as you get closer to the rack, and becomes "O" at the target track position. 15 is a switching circuit, 16 is a power amplifier, and the difference signal from the speed error creation circuit 14 via the switching circuit 15 is A voice coil motor (VCM) 17 drives the carriage of the head 10, and a drive current corresponding to the differential signal from the power amplifier 16 is supplied to the voice coil motor 17. The above-mentioned position signal generation circuit 11, speed signal generation circuit 12, and speed error generation circuit 14
Drive control of the head 10 based on the differential signal that has passed through the above realizes coarse control.

Further, in the same figure, reference numeral 18 is a filter circuit used for PID control, and the position signal from the position signal generation circuit 11 becomes a position error signal through the filter circuit 18, and the position error signal is sent to the power amplifier l6 via the switching circuit 15. is provided. The position control of the head 10 based on the position error signal passed through the position signal generation circuit 11 and the filter circuit 18 realizes fine control.

Reference numeral 19 denotes a switching command circuit that issues a command to switch the control mode between coarse control and fine control, and this switching command circuit 19 transmits to the switching circuit 15 the state of the speed error creation circuit 14 during coarse control. When it is determined that the head 10 has sufficiently decelerated and reached the vicinity of the target track, a switching command is issued to the filter circuit 18 side.

A timer circuit 20 outputs a read/write permission signal as a positioning completion signal after a predetermined time TO from when the switching command circuit 19 outputs the switching command. The time To set in the timer circuit 20 is the time required for the head 10 to be positioned on the target track by fine control, and is determined experimentally (for example, about 0.5 to 3 msec). .

In such a head positioning control device, the head 1
When accessing 0, the number of tracks crossed is counted based on the position signal from the position signal generation circuit 11, and speed control is performed so that the target speed corresponds to the count value (number of tracks) at each point in time. 10 is moved in the forward or reverse direction by the number of tracks (count number) (coarse control). And head 1
0 is sufficiently close to the target track and the speed of the head 10 has become sufficiently slow, the switching circuit 15 is switched to the filter circuit 18 side by a command from the switching command circuit 19, and the head 10 is switched to the filter circuit 18 side based on the position error signal. control to the target track (fine control). At this time, when the set time To in the timer circuit 20 has elapsed since the switching of the switching circuit 15, a read/write permission signal is output from the timer circuit 20, and after that, the read/write permission signal is outputted from the timer circuit 20.
Data is written/written via the write head.

[Problem to be solved by the invention]

In the conventional head positioning control device as described above, when attempting to speed up head access, read/write errors tend to occur.

This is based on the following reasons.

In order to speed up access to the head, it is necessary to increase the frequency band of the coarse control loop in order to improve the response characteristics of each circuit. That is, the speed signal generation circuit 12
, the frequency band of the speed error creation circuit 14 etc. is set high,
This increases the frequency band of the drive current for the voice coil motor for driving the head.

However, when the frequency band of each circuit is increased in this way, each circuit responds to vibrations of the mechanical section including the head, and the mechanical section controlled by the circuit becomes likely to vibrate at its resonant frequency. Then, a positioning completion signal is output a predetermined time after switching from coarse control to fine control, but by that time, the vibration of the head has not been sufficiently attenuated due to the resonance phenomenon, and the head is in an offset state with respect to the target track. This results in a read/write error.

Furthermore, continuous movement of the head (seek operation) increases the vibration of the head, further increasing the possibility of read/write errors.

SUMMARY OF THE INVENTION An object of the present invention is to prevent the phenomenon in which vibrations of the head remain after a positioning completion signal is outputted due to resonance caused by high-speed movement of the head.

[Means to solve the problem]

As shown in FIG. 1, the present invention includes a first control stage 3 that drives and controls the head 1 from the current position toward the target track 2, and a first control stage 3 that controls the drive of the head 1 from the current position to the target track 2, and moves the head 1 to the target track based on the detected position of the head 1. A second control means 4 controls the position on the magnetic head 2, and a first control unit controls the magnetic head 1 when the head 1 reaches a predetermined vicinity of the target track 2 by drive control in the first control stage 3. a control mode switching step 5 for switching from drive control by the means 3 to position control by the second control means 4;
The present invention is based on a head positioning control device equipped with a completion signal output stage 6 that outputs a positioning completion signal after a predetermined period of time has elapsed since the switching by the control mode switching means 5. , the technical means for solving the above problem includes a vibration detection stage 7 that detects the vibration level in the resonant frequency band of the head mechanism including the head, and a vibration detection stage 7 that detects the vibration level according to the detected vibration level in the vibration detection stage 7. 1,000 timing adjustment stages 8 for adjusting the output timing of the positioning completion signal from the completion signal output stage 6.

The control mode in the first control stage 3 is not particularly limited,
For example, it may be speed control or position control depending on the distance to the target track, or it may be a simple open-loop control mode.

Further, the timing adjustment means 8 delays its output timing as the detected vibration level increases, and the manner in which the output timing is adjusted is arbitrary. For example, the output timing may be adjusted linearly according to the vibration level, or when the vibration level exceeds a certain level, the normal output timing may be further delayed by a certain amount.

[Effect]

When the head 1 is accessed, the first control stage 3 drives and controls the head 1 toward the target track 2. and,
When the head 1 reaches a predetermined vicinity of the target track 2. The control mode switching means 5 switches to the second control stage 4, and this second control stage 4 controls the position of the head 1 with respect to the target track 2. When the control mode switching step 5 is switched, a positioning completion signal is outputted from the completion signal output step 6. However, when the first control means 3 performs drive control, the vibration detection means 7 The vibration level in the resonant frequency band of the mechanical part is detected, and the timing control means 8
The above completion signal is output in accordance with this detection signal level.
Adjust the output timing of the positioning completion signal from.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a block diagram showing an example of the basic configuration of a head positioning control device according to the present invention. This example, like the one shown in Figure 4, basically realizes two control systems: coarse control, which controls the speed of the magnetic head according to the distance to the target track, and fine control, which controls the position on the target track. ing.

In FIG. 2, the coarse control system includes a position signal generation circuit 11 that demodulates a servo signal from the head 10 into a position signal as in the conventional case, a speed signal generation circuit 12, a target speed generation circuit 13, and a speed error generation circuit 14. A drive current based on the differential signal from the speed error generation circuit 14 is coupled to a voice coil motor 17 (for driving the head 10) via a power amplifier 16.
The fine control system is also the same as the conventional one, and the position signal from the position signal generation circuit 11 is supplied to the power amplifier 16 as a position error signal through the filter circuit 18.

Further, the switching circuit 15 and switching command circuit 19 for switching between the coarse control system and the fine control system have similar configurations.

On the other hand, the speed signal from the speed signal generation circuit 12 is input to the band pass filter 21. This bandpass filter 21 has a bandwidth characteristic corresponding to the resonance frequency band of the head mechanism including the head 10, and the characteristic is determined based on the structure of the disk device. van 1
An example of the characteristics of the pass filter 21 is shown in FIG. By using a filter with the characteristics shown in the figure, only the vibration component due to mechanical resonance can be extracted. A vibration level detection circuit 22 is provided after the bandpass filter 21, and the level of the vibration component via the bandpass filter 21 is detected. Further, a timer circuit 20 is provided downstream of the switching command circuit 19, as in the conventional case, but this timer circuit 20 operates when the detection level of the vibration level detection circuit 22 is below a predetermined level. If the same time TO as before is set and the detection level exceeds the predetermined level,
A further delayed time T1 is set. The vibration detection slice of the vibration level detection circuit 22 is determined so that the vibration component appearing in the speed signal is applied to the slice and can be detected during the seek when the vibration exceeds a certain level (Examples 2 to 3 Bm) after the end of the seek. The above setting time in the timer circuit 20 (
Basically, it is the time required for positioning on the target track by fine control as in the past, and the normal time To is assumed to be the vibration damping characteristic of the head 10 when the head mechanism is not in a resonant state. The delayed time T1 is determined assuming the vibration damping characteristics of the head 10 in the resonance state.

In the above-mentioned control device, when performing coarse control, for example, as shown in FIG. 1.Further damping characteristics ■. The speed to the target track Tro is controlled at a target speed of 2. At this time, if the head mechanism vibrates in the resonant frequency band, the bandpass filter 2
1 is detected by the vibration level detection circuit 22. Then, when the vibration level exceeds a predetermined level, the predetermined time of the timer circuit 20 becomes time T1, which is delayed. As a result, when the above-mentioned coarse control ends and the position control to the target track is switched to fine control, the timer circuit 20 issues a read/write permission as a positioning completion signal after the delayed time Tl from the time of the switch. A signal is output.

As mentioned above, if the head mechanism vibrates in the resonant frequency band, the output timing of the read/write permission signal will be delayed, and the read/write will be performed while the vibration of the head 10 is sufficiently damped. will be done.

Therefore, read/write errors are prevented from occurring.

Incidentally, when the vibration level detected by the vibration level detection circuit 22 is below a predetermined level, the timer circuit 20 enters the setting state of the time To, as in the conventional case, and the time T is set from the start of the fine control.
After o, a read/write permission signal is output.

〔Effect of the invention〕

As described above, according to the present invention, since the output timing of the positioning completion signal is adjusted according to the vibration level in the resonance frequency band of the head mechanism, vibration occurs when controlling the position of the head. Even if the head is accessed at high speed, read/write errors are less likely to occur.

As a result, high-speed head movement control (seek control) accompanied by vibration generation becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing an example of the basic configuration of the head positioning control device according to the present invention, FIG. 3 is a characteristic diagram showing the head speed control state, and FIG. Figure 4 is a block diagram showing an example of the basic configuration of a conventional device.
FIG. 5 is a diagram showing an example of characteristics of a bandpass filter. 1, 10...Head 2...Target track 3...First control means 4...Second control means 5...1000-step control mode switching 6...Completion signal output means 7. ... Vibration detection means 8 ... Timing adjustment means

Claims (1)

[Claims] First control means (3) for driving and controlling the head (1) from the current position toward the target track (2);
A second control means (4) controls the position of the head (1) on the target track (2) based on the detected position of the head (1), and the first control means (3) drives the head (
1) reaches a predetermined vicinity of the target track (2), control of the head (1) is switched from drive control by the first control means (3) to position control by the second control means (4). Control mode switching means (5) and control mode switching means (5)
In a head positioning control device comprising a completion signal output means (6) for outputting a positioning completion signal after a predetermined period of time has elapsed since the switching is performed, the vibration level in the resonant frequency band of the head mechanism including the head. vibration detection means (7) for detecting vibration detection means (7);
7) A head positioning control device comprising: timing adjustment means (8) for adjusting the output timing of the positioning completion signal from the completion signal output means (6) according to the vibration level detected in step 7).