JPH0632177B2 - Servo head offset method in servo tractor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a write position error of a servo pattern due to a variation in size of a servo head in a servo track writer.

[Prior Art] In an HDA (head disk assembly) servo track writer, the servo head (servo pattern writing head) is replaced about once a month. At the time of this replacement, it is necessary to prevent the occurrence of an error at the writing position of the servo pattern by the replaced servo head due to the variation in the size of the servo head. An example of the method that has been conventionally used for that purpose is as follows.

(1) After replacing the servo head, read predetermined reference track data from the laser measurement value / track table, and based on the data, extend the servo head onto the magnetic disk in the HDA, and position the reference track. Write to.

(2) Next, remove the HDA from the servo track writer,
The physical track position on the written magnetic disk is examined by destructive inspection using a separate inspection device.

(3) Deviation between the physical track position thus examined and the position of the reference track read from the table (this is the difference between the size of the servo head after replacement and the standard size of the servo head). The laser measurement value of each track in the table is offset according to the amount of the deviation (if the deviation exceeds a certain amount, the origin position of the head is specified. By adjusting the position of the stopper, the mechanical offset of the origin position itself is performed together with the offset of the laser measurement value).

(4) The above steps (1) and (2) are repeated for another HDA based on the offset table, and it is confirmed whether or not the deviation is compensated.

[Problems to be solved by the invention]

However, in such a method, there is a problem that destructive inspection must be performed for the offset processing and the confirmation processing after the offset, which requires time and labor and is inefficient.

The present invention has been made to solve the above problems.

[Means for solving problems]

After replacing the servo head, set a reference disk type recording medium in which data is pre-written on a predetermined reference track,
The first step of feeding out the servo head to the reference disk-type recording medium and searching for the reference track, and detecting the reference track using a position measuring device for detecting the position of the servo head At this time, the actual feed amount from the origin position of the servo head is detected,
A second step of obtaining a deviation between the detected actual feed amount and a predetermined standard feed amount from the origin position of the servo head with respect to the reference track, and a stopper position for defining the origin position of the servo head are set. By making it adjustable, the origin position can be variably adjusted,
When the deviation obtained in the second step exceeds a predetermined amount, the position of the stopper is adjusted to mechanically shift the origin position of the servo head so that the deviation is adjusted to fall within the predetermined amount. It is characterized by comprising a third step and a fourth step of offsetting the feeding position of the servo head according to the amount of the deviation when the servo head is subsequently positioned.

[Action]

The shift between the actual feed amount and the standard feed amount corresponds to the shift between the size of the servo head after replacement and the standard size of the servo head. Therefore, by offsetting the feeding position of the servo head in accordance with the amount of this deviation, the deviation is compensated and the occurrence of a writing position error is prevented.

According to this offset method, the offset is performed based on the search for the reference track of the disk type recording medium, so that the offset process can be performed quickly and easily. Further, the confirmation process after the offset can be similarly quickly and easily performed by re-feeding the servo head onto the reference track. Therefore, it is possible to prevent the writing position error from occurring quickly and easily.

〔Example〕

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

FIG. 1 shows an HD to which the offset method according to the present invention is applied.
3 is a partial view of the A servo track writer. Reference numeral 1 is a servo head, 2 is an arm to which the head 1 is attached at the tip, and which is rotatably supported by a fixed shaft 3, and 4 is a stopper for the arm 2, which is made of a screw. The position of the head 1 when the arm 2 is in contact with the stopper 4 is the origin position of the head 1 (therefore, the origin position of the head 1 can be changed by rotating the screw to adjust the position of the stopper 4). ). The arm 2 is rotated by a driving unit (not shown) to move the head 1 from the origin position with respect to the magnetic disk in the HDA positioned on the servo track writer.

5 is a laser length measuring device for measuring the amount of extension of the head 1 from the origin position (the length measuring device 5 recognizes the position of the head 1 when the head 1 has been stationary for a certain time or longer) as the origin position.
Is a laser measurement value / track table, and 7 is a control unit for controlling each unit of the servo track writer.

In this servo track writer, when the head 1 is replaced, the occurrence of a write position error of the servo pattern due to the variation in the size of the servo head is prevented by the following method.

(1) 0 track as shown in Fig. 2 (outermost track)
The master HDA 9 having the magnetic disk 8 in which the data has been written in advance is positioned on the servo track writer.

(2) Under the control of the control unit 7, the arm 2 is driven by the driving means.
The head 1 after replacement is delivered by rotating the
Find the 0 track.

(3) The control unit 7 obtains the deviation between the actual length measurement value of the length measuring device 5 when the 0th track is searched and the laser length measurement value corresponding to the 0th track in the table 6.

(4) If the calculated deviation is less than a certain amount, the control unit 7 offsets the laser measurement value of each track in the table 6 according to the deviation amount. On the other hand, if the deviation exceeds the predetermined amount, the position of the stopper 4 is manually adjusted, so that the origin position of the head 1 itself is mechanically offset together with the offset of the laser measurement value.

(5) Under the control of the control unit 7, by feeding the head 1 onto the 0 track based on the table 6 after the offset,
Check whether the deviation has been compensated.

In this embodiment, 0 track of the magnetic disk 8 is used as a reference track, but any track may be 0 track.

〔The invention's effect〕

As described above, according to the offset method of the present invention,
It is possible to quickly and easily prevent the writing position error of the servo pattern due to the size variation of the servo head. Therefore, the efficiency of the servo pattern writing process in the servo track writer can be improved as a whole.

[Brief description of drawings]

FIG. 1 is a top view partially showing a servo track writer to which the offset method according to the present invention is applied, and FIG.
Master H positioned on the servo track writer in the figure
It is a figure which shows the state which extended the servo head on 0 track of the magnetic disc in DA. 1 ... Servo head, 2 ... Arm, 3 ... Fixed axis, 4
...... Stopper, 5 ... Laser length measuring device, 6 ... Laser length measurement / track table, 7 ... Control unit, 8 ... Magnetic disk, 9 ... Master HDA.

Claims (1)

[Claims] 1. After replacement of a servo head, a reference disk-type recording medium in which data is previously written in a predetermined reference track is set, and the servo head is extended to the reference disk-type recording medium. First to find the reference track
And the actual feed amount from the origin position of the servo head when the reference track is detected using a position measuring device for detecting the position of the servo head, and the detected actual A second step of obtaining a deviation between the feed amount and a predetermined standard feed amount from the origin position of the servo head with respect to the reference track; and adjusting the position of a stopper for defining the origin position of the servo head. By this, the origin position can be variably adjusted, and when the deviation obtained in the second step exceeds a predetermined amount, the position of the stopper is adjusted to mechanically shift the origin position of the servo head. Third adjustment to adjust the deviation within a predetermined amount
And a fourth step of offsetting the feeding position of the servo head according to the amount of the deviation at the time of positioning the servo head thereafter, the servo head offset method in the servo track writer.