JPH04238171A - Detection of servo write start position - Google Patents

Abstract

PURPOSE:To stably detect the write start position of servo patterns to a mag netic disk with high accuracy. CONSTITUTION:A position detecting pin is moved to the track to be checked and a check signal is written from the magnetic disk. The position detecting pin is then moved by one track and after an erase signal is emitted, the pin is returned again by one track and thereafter, the write start position is detected by whether the above-mentioned check signal can be detected or not. The contact of the magnetic head and the position detecting pin is stably detected with the high accuracy. The write start position of the servo patterns is thus stably detected and set with the high accuracy.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo write start position detection method for detecting a servo pattern write start position on a magnetic disk.

0002

2. Description of the Related Art Magnetic recording media formed in the form of disks include flexible floppy disks and hard disks formed of hard metal materials. Hard disks are used for recording/playback of high storage capacity. There is. This hard disk employs closed-loop control to perform fine tracking, and servo patterns are written in the hard disk to perform this closed-loop control. That is, the hard disk is provided with one to several write protect areas per revolution of each track in which the user cannot write information, and staggered servo patterns are written in these write protect areas at the time of shipment from the factory. Then, this servo pattern is read out from the magnetic disk during storage/reproduction or during servo correction performed at a preset timing, and servo correction is performed to realize fine tracking.

The writing start position of the servo pattern on the magnetic disk is determined with high accuracy (20 to 50 μm) on the magnetic disk.
It is necessary to detect and start writing at step m), and generally a closed loop method is used in which a reflecting mirror is attached to the arm of the head and a laser interferometer is used to detect the writing start position. However, this closed-loop method requires a complicated device configuration, is not easy to detect, and has problems in terms of equipment cost.

[0004] Therefore, using a stepper and a rotary encoder, the position detection pin is moved by the stepper,
A semi-closed loop method has been proposed in which the writing start position is detected by pressing this position detection pin against the arm of the magnetic head. In this case, it is necessary to start writing the servo pattern from the end position where the arm contacts the stopper, but it is required to detect that the position detection pin has contacted the arm of the magnetic head.

[0005] Therefore, in the semi-closed loop method, the following detection method has been proposed. (1) The arm is made of a conductive material and electrical continuity is detected when the position detection pin contacts the arm. (2) A signal is written from the magnetic head to the magnetic disk at the contact position of the arm and the stopper. Next, a position detection pin is sent while reading out the written signal, and the arm is moved by the sent position detection pin to be in an off-track state, and the position where the signal is no longer read is detected. (3) Principle of (2) above. Based on this, the signal written by the magnetic head is read out, displayed on an oscilloscope, and while the waveform is monitored, a position detection pin is manually sent in to detect the changing position of the waveform.

[0006]

[Problem to be solved by the invention] The method (1) above is:
The arm must be electrically conductive, and cannot be applied to currently used arms that do not conduct electricity even if the position detection pin contacts them. In addition, if the arm of a disk drive device is made of conductive material as described above, all the mounting jigs must be made of insulating material, which requires major modification of the device and results of experiments with the actually modified device show poor contact. It has been confirmed by the present inventors that accidents are likely to occur.

Furthermore, according to method (2) above, since the stopper part is made of rubber to prevent impact, the magnetic head shifts due to the elastic deformation force of the rubber several seconds after contact, and the written signal is read out. position detection may become unstable. The method (3) has the same problems as the method (2) described above, and also has the disadvantage that it takes a long time to detect the position and automatic operation is not possible.

The present invention has been made in view of the current state of the servo write method as described above, and its object is to be able to stably and accurately detect the writing start position of a servo pattern on a magnetic disk. An object of the present invention is to provide a method for detecting a servo write start position.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention detects the writing start position on the magnetic disk of a servo pattern written on a magnetic disk and read out during servo correction of the magnetic disk. In the servo write start position detection method, a swing arm having a magnetic head is biased against a stopper that restricts the rotation range, and a position detection pin is advanced by one track in a direction that rotates the arm in the opposite direction to the bias direction. Then, a confirmation signal is written from the magnetic head to the magnetic disk, and then the position detection pin is moved forward by one track, an erase signal is output from the magnetic head, and the position detection pin is moved back by one track, and then the confirmation signal is written. When a signal is detected, the position detection pin comes into contact with the swing arm and moves to detect the writing start position.

0010

[Operation] When the arm is moved by moving the position detection pin by the above means, the written confirmation signal will not be erased even if an erase signal is issued. On the other hand, if the position detection pin moves one track but does not come into contact with the arm, the arm's magnetic head will not move to the next track, so the magnetic head will remain on the track where the confirmation signal is written. In this state, an erase signal is issued and the written confirmation signal is erased. Thereby, it is determined whether or not it is the starting position for writing the servo pattern onto the magnetic disk.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to FIG. 1, which shows the method. Although not shown in the drawings, the disk drive device includes, as a detection device, an encoder, for example, disposed coaxially with the swing arm, and the encoder detects the rotational position of a rotary plate provided with a position detection pin. The rotation of this rotating plate is controlled by a stepper. Furthermore, a pair of stoppers are provided to restrict the range of rotation of the arm. This position detection pin is configured to be able to come into contact with the arm and move the arm in the radial direction of the magnetic disk.

FIG. 1 is a flowchart showing the write start position detection operation. In step S1 of FIG. 1, the arm is moved to hit the stopper in order to start writing the servo pattern from the end position of the write protect area. Then, the process proceeds to step S2, where a confirmation signal is written on the magnetic disk by the magnetic head. Initially, the position detection pin is moved to a position where it is not in contact with the swing arm. Next, in step S3, it is checked whether the confirmation signal has been reliably written on the magnetic disk by reading it with a magnetic head, and if it has been written (YES in S3), the process advances to step S4. In step S4, the position detection pin is advanced one track by the stepper, and in step S5, an erase signal is sent to the magnetic head to perform erasing. Next, in step S6, the position detection pin is moved backward by one track using the stepper, the signal is read out in step S7, and it is determined in step S8 whether or not the confirmation signal has been turned off. In this case, if the swing arm has been sent to the next track by the position detection pin in step S4, the position detection pin will move the swing arm to the next track.
Since the magnetic head is not located on the track where the confirmation signal is written during erasing in step 5, the confirmation signal is not erased. Therefore, if the determination in step S8 is YES, it can be detected that the writing start position of the servo pattern is reached.

On the other hand, if the determination in step S8 is NO, it means that the magnetic head (swing arm) has not moved due to the advancement of the position detection pin in step S4, and the magnetic head and the position detection pin are not in contact with each other. Since it is not, the position detection pin is advanced two tracks in step S9 and step S2
Returning to step S8, the operations from step S2 to step S9 are repeated until the determination at step S8 becomes YES. Since the operations from step S2 to step S9 are completed in less than 0.5 seconds, detection can be performed without being affected by the elastic deformation of the stopper as in conventional methods, and the detection accuracy is also 1.
Since the track is 19 microns, detection can be performed with sufficient accuracy.

As described above, according to the above embodiment, there are no troubles caused by poor electrical contact or malfunctions caused by elastic deformation of the stopper as in the conventional method, and the magnetic field of the servo pattern is easily placed at the end position of the write protect area. The writing start position on the disk can be detected and set stably and with high precision.

[0015]

[Effects of the Invention] As explained above, according to the present invention,
The writing start position of the servo pattern on the magnetic disk can be detected stably and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a flowchart illustrating an embodiment of the present invention.

Claims (1)

[Claims] 1. A servo write start position detection method for detecting a write start position on a magnetic disk of a servo pattern written on a magnetic disk and read out during servo correction of the magnetic disk, comprising rotating a swing arm having a magnetic head. energizes the stopper that restricts the range of movement,
Move the position detection pin forward one track in the direction opposite to the biasing direction to write a confirmation signal from the magnetic head to the magnetic disk, and then move the position detection pin forward one track to read the magnetic disk. After outputting an erase signal from the head and moving the position detection pin backward by one track, when the confirmation signal is detected, the position detection pin moves in contact with the swing arm and confirms that it is at the write start position. A servo light start position detection method characterized by: detecting a servo light start position.