JPS61199280A - Access control system for disk device - Google Patents

Abstract

PURPOSE:To prevent the uncontrollable run of an actuator and to suppress impact applied to a head by detecting abnormality of access by a residual signal of an objective track and a present track of a head and an access abnormality area detecting signal, and decelerating the actuator. CONSTITUTION:A present track of a head is detected by a track position detector 25, a track pass pulse generator 26 and a track address counter 27 based on servo signals from a servo head. Residual number of the present track and an objective track stored in an objective track register from a host controlling device 24 is calculated by a subtracter circuit 28, and supplied together with an area signal by a missing pattern based on the servo signal from an area detector 30, and an access abnormality signal is outputted from an access abnormality detector 29. Then, the actuator is decelerated through a target speed outputting device 31. As abnormality is detected while the head is in the data area, uncontrollable run of the actuator is prevented, and impact applied to the head is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an access control method for a disk device, and more particularly to a method for moving a magnetic head on a rotating medium such as a magnetic disk.

[Background of the invention]

Conventionally, the positional information obtained with disk drives that control actuator movement using a feedback loop system is discontinuous periodic positional information with the zero level at the center of each track. The head position is relatively recognized by counting the number of . In this case, if there is an error in counting the tracks or a misrecognition of the track position before the head is accessed, it is impossible to visually grasp the position information of the head that is being accessed. For this reason, an access abnormality of the actuator cannot be detected, and the access abnormality is detected after the actuator moves out of the data recording/reproducing area.

However, from that point on, it is no longer possible to decelerate effectively, and the actuator collides with the stopper, causing a problem in that an impact is applied to the head section. Also,
Optical disk devices that have a supply address are disclosed in Japanese Patent Application Laid-open No. 58.
Although described in Japanese Patent No. 97145, this example is required specifically for an optical disk having a spiral track, and is completely different from a magnetic disk device having a circular track.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an access control method for a disk device that solves these conventional problems, prevents the actuator from running out of control during an access operation, and suppresses the impact applied to the head section.

[Summary of the invention]

In order to achieve the above object, in the present invention, a disk consisting of a data surface dedicated to data recording and reproduction and a servo surface on which head positioning information is recorded is mounted on a drive spindle,
In a disk device in which the head is moved by an actuator, there is a detection means for detecting an area signal recorded on the inside and outside of the head positioning information on the servo surface to prevent the head from falling off, and a detection means for detecting the target track and the current state of the head. A residual track detection means is provided to detect the number of residual tracks with respect to the track position, and when an abnormality occurs in the control system of the actuator, the position of the moving head is detected by the area signal and the number of residual tracks, and the access operation is performed. The feature is that the abnormal state is detected and the actuator is decelerated from the time of detection.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a side sectional view of a magnetic disk device to which the present invention is applied.

A disk 2 is attached to a spindle 1 and rotates. On the disk 2, there are a data surface 3 dedicated to data recording and reproduction and a servo surface 4 on which head positioning information is recorded, and a data head 5 and a servo head 6 corresponding to each surface are provided.
I read and write.

These heads are fixed to the actuator tough.

The actuator 7 can move in the normal direction of the disc 2, but its movement range is limited by a stopper 8 to prevent contact between the actuator 7 and the disc 2 and to prevent the head from falling off the disc 2. There is.

A position information signal for positioning the data head 5 on the track is recorded on the servo surface 4. This position signal is approximately 17 track widths to the left and right of the track center.
This is a position signal with a linearity of about 4, and it is possible to obtain a periodic position signal for each track as the head moves. This periodic track position signal is used to count the number of tracks passed during access control and is recorded over the entire range of movement of the actuator.

FIG. 3 is a diagram showing a servo pattern recorded on the servo surface 4 and a readout signal.

The recording pattern 9 has synchronization bits 13 and 14 for obtaining a rotation synchronization signal in addition to position bits 12 arranged alternately left and right with respect to the center 10 of the track. Furthermore, a missing clock bit 14 can be provided in the synchronization bits, which lacks part of the pattern in the synchronization bits. Here, 1 normal synchronization bit is ``0'', missing clock bit 14 is tr I N, II O'' and II I
With the combination pattern II, band information can be recorded on the servo disk separately from the track position signal.

FIG. 4 is a diagram showing the recording state of band information on the servo surface 4. FIG.

Directing inward from the disk edge 16, there are an external protection band (hereinafter referred to as OGB) 17 and an external data band (hereinafter referred to as OD).
B) 18, data band (hereinafter referred to as DB) 1
9. It is divided into an internal data band (hereinafter referred to as IDB) 20 and an internal protection band (hereinafter referred to as IGB) 21.

The operating range of the head is range 22, and the data recording/reproducing range is range 23.

During access control, the disk device records the head position in a counter in the access control circuit, and increases or decreases the number by ±1 every time the head crosses a track. However, in the case shown in the first example, the access control circuit enters an access abnormal state. Namely.

(1) If the number of tracks is incorrectly counted, (11) If the track look position before the start of access is incorrectly memorized, (iii) The number of tracks in the access command is sent from the control device as the total number of pulses. Disfusing device of the type that can be used
In other words, in a disk device that starts the access operation before receiving all pulses, and initializes the head position by positioning it on the O track by receiving pulses exceeding the total number of tracks, the actual head position and control device There may be cases where the internally stored track position information is different. This means that in the conventional system, the head is connected to the protective band IGB.
This is because an abnormal access state of the access control circuit can be detected even when the access control circuit is in GB 21 or GB17. Therefore, a collision between the actuator 7 and the stopper 8 was unavoidable. However, within the data area, the bands ODB 18 and IDB 2 at both ends of the data area
If O can be detected, an abnormality in access control can be known based on that information. That is, OGB l
If there is a head in ODB 7 and its access direction is toward the outer circumference, the number of remaining tracks from the head to the access target track will not be greater than the number of tracks included in ODB l a. If it is large, it is assumed that the access is abnormal and the speed is reduced immediately. IGB2
A similar process is performed when the head is located inside the head and the head is accessed toward the inner circumference.

FIG. 1 is a block diagram of an access system including an access abnormality detection circuit showing one embodiment of the present invention.

In FIG. 1, 7 is an actuator that moves the head, 24 is a host controller that controls the speed of the actuator, 25 is a track position detector that detects the track position from a servo signal, and 26 is a track position detector. 25
27 is a track address counter that stores the current track position of the head. 28 is a track address counter that stores the position of the track where the head is currently located. The number of residual tracks shown is 29, an access abnormality detector that detects an abnormality in head access, 30 an area detector that detects an access abnormality area, and 31 a system that changes the target speed between normal access and access abnormality. A target speed output device 32 is a power amplifier that amplifies the difference between the target speed and the actual speed signal.

33 is a target track register in which the target track is stored.

First, when an access command is output from the host control device 24, the target track is stored in the target track register 33 and access is started. The servo signal read from the servo head 6 is input to the track position detector 25,
A track position signal is obtained. This signal is pulsed by a track passing pulse generator 26 and input to a track address counter 27. A track address counter 27 stores the position of the track where the head is currently located. The difference between this and the target track is calculated to obtain the number of residual tracks 28, which is output to the access abnormality detector 29. On the other hand, the area detector 30 outputs an area signal to the access abnormality detector 29 based on the missing pattern of synchronization bits included in the servo signal. The access abnormality detector 29 detects an access abnormality from the residual track number 28 and the area signal, and sends a signal to the target speed output device 31 to immediately reduce the speed.

The target speed output device 31 normally outputs a target speed corresponding to the number of residual tracks 28 to the power amplifier 32, but when an access abnormality occurs, it outputs a target speed that immediately decelerates. The power amplifier 32 amplifies the difference between the target speed and actual speed signals, operates the actuator 7, and moves the head.

In this way, according to this embodiment, abnormal operation during an access operation can be detected while the head is in the data area.

〔Effect of the invention〕

As described above, according to the present invention, an abnormal operation during an access operation can be detected while the head is in the data area, so that it is possible to decelerate the actuator until it collides with the stopper.

This has the effect of preventing excessive impact from being applied to the head.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an access system including an access abnormality detection circuit showing an embodiment of the present invention, FIG. 2 is a sectional side view of a disk device to which the present invention is applied, and FIG. FIG. 4 is a diagram showing the area (band information) recorded on the servo surface. 1 spindle, 2: disk, 3: data surface, 4: servo surface, 5: data head, 6: servo head, 7: actuator, 8: stopper, 9: servo recording pattern,
10 Nidrak center, 11, 12: position bit, 13:
Synchronization bit, 14: Missing clock bit, 15:
Servo read signal, 16: Disk end, 17: External protection band (OGB), 18: External data band (ODB)
, 19: Data band (DB), 20: Internal data band (IDB), 21: Internal protection band (IGB), 22
: Head operating range, 23; Data recording/reproducing range, 24:
Upper control device, 25 rack position detector, 26: track passing pulse generator, 27: h rack address counter, 28: number of residual tracks, 29: access abnormality detector, 30: area detector, 31: target speed output 32: power amplifier, 33: target track register. Figure 3

Claims (1)

[Claims] (1) In a disk device in which a disk consisting of a data surface dedicated to data recording and reproduction and a servo surface on which head positioning information is recorded is mounted on a drive spindle and the head is moved by an actuator, the head positioning information on the servo surface A detection means for detecting area signals recorded on the inside and outside of the head, and a residual track detection means for detecting a residual track between the target track number and the current track position of the head are provided. If an abnormal state of access operation occurs, the position of the moving head is detected by an area signal and the number of residual tracks, and the actuator is decelerated from the time of detection.