JPH0754619B2 - Servo signal writing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a head positioning servo pattern of a magnetic disk device, and in a servo signal writing device, it is particularly necessary to verify a written pattern of a head. Move
The present invention relates to a positioning device.

[Common technology]

Generally, a servo signal writing device for a magnetic disk includes a means for writing a prescribed servo pattern and a means for verifying whether the written servo pattern is normal.

[Conventional technology]

In a conventional servo signal writing device, as a head moving method for verifying a servo pattern, a servo pattern of one track is often written, the servo pattern of the same track is read and checked, and then the next track is often moved.

[Problems to be solved by the invention]

Since the conventional servo signal writing device described above verifies the servo pattern written on the same track after writing the servo pattern, the magnetic disk once removed from the servo signal writing device is re-served as the servo signal. If you try to verify only the written servo pattern by attaching it to the writing device, or if you try to verify the servo pattern of the magnetic disk written by another servo signal writing device, do the writing operation. Even if only the verification operation is performed without this, the reproducibility of the head position is not guaranteed, and there is a drawback that accurate verification cannot be performed. What is required is that the track width of the magnetic disk is on the order of tens of μm, and head positioning accuracy of several μm or less is required. This is because a head position shift that is unverifiable can easily occur due to thermal deformation of the disk itself.

[Means for solving problems]

The servo signal writing apparatus of the present invention includes a boundary detecting means for detecting a boundary between a servo area and a guard band area from a servo pattern, an approximate distance from the boundary to an outermost track to be inspected, and an entire track area to be inspected. A length measuring device for measuring a rough distance of track intervals, means for moving the servo signal read head from the boundary to the vicinity of the end track while reading the output value of the length measuring device, and the servo signal read head. A means for moving approximately one track while reading the output value of the length measuring device, a demodulation circuit for producing a head positioning position error signal from the servo pattern signal read by the servo signal reading head, and a head positioning position error signal are provided. And means for moving and positioning the servo signal read head so as to minimize it.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of the present invention.

A head 1 for writing and reading a servo pattern is fixed to a head drive unit 2, and when the head drive unit 2 moves, it is moved or positioned in the radial direction on the magnetic disk surface.

The movement and stop operation of the head drive unit 2 are controlled by the control signal a from the arithmetic unit 3. The moving amount of the head drive unit 2 is measured by the length measuring device 4 and the length measuring data b is sent to the arithmetic unit 3.

On the other hand, the read signal c read by the head 1 is the read circuit 5
The signal is amplified by and then applied to the boundary detection circuit 6 and the demodulation circuit 7.

The boundary detection circuit 6 discriminates the difference in the servo pattern configuration as shown in FIG. 2, for example, generates a servo area signal for distinguishing the servo area from the guard area, and sends it to the calculator 3 as a boundary signal d.

The demodulation circuit 7 produces a repetitive position error signal e from the servo pattern proportional to the distance of the head from the boundary of the servo pattern writing track, as shown in FIG.
Send to D converter 8. The position error signal e is converted into a digital signal by the A / D converter 8 and input to the calculator 3.

As a boundary detecting means, a method of directly detecting the output signal of the reading circuit 5 by the arithmetic unit 3 instead of the boundary detecting circuit 6 is of course possible. The demodulation circuit 7 is a circuit system that is widely used in magnetic disk devices that employ a head positioning system using servo surface servo, and therefore detailed description thereof is omitted.

Next, the operation will be described step by step.

First, the head drive unit 2 is driven by the control signal a from the arithmetic unit 3, and the arithmetic unit 3 monitors the output boundary signal d of the boundary detection circuit 6 while moving the head 1. When the change point of the boundary signal d, that is, the boundary point A between the servo area and the guard area is reached, the movement of the head 1 is stopped and the length measurement data B at that point is taken into the arithmetic unit 3.

The distance between the boundary point A and the end (innermost) track point B to be verified is designated in advance in the computing unit 3. The computing unit 3 adds the distance data between A and B to the length measurement data at the boundary point A, and while monitoring the length measurement device data, moves the head drive unit to the point of the result and stops it.

Next, the computing unit 3 monitors the position error signal e input through the A / D converter 8 and finely moves and positions the position error signal e so that the value of the position error signal e is minimized.

The servo pattern of the first track is verified at this positioning point.

To move to the next track, after the head drive unit 2 is moved by the calculator 3 to a point where the track pitch data specified in advance is subtracted from the length measurement data at the local point and stopped, the position error signal e The position is repositioned again with a slight movement so that the value becomes the minimum. Servo pattern verification of the second track is performed at this positioning point.

In the following, the servo pattern verification of all tracks is performed by the same positioning procedure.

〔The invention's effect〕

When verifying a servo pattern, the servo signal writing device of the present invention first determines the approximate position of the head by using the length measurement data, then looks at the position error signal and finely moves the head to the optimum position for verification. By doing so, there is an effect that the servo pattern can be accurately verified again even if the magnetic disk once removed from the servo signal writing device is re-attached or is thermally deformed.

Further, instead of moving the head relying only on the position error signal, the length measurement data and the position error signal are used together, so even if there is a defect in the servo pattern, verification operation at the wrong position is not performed. There is an effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing generation of a boundary signal d, and FIG. 3 is generation of a position error signal e. It is a waveform diagram showing. 1 ... Head, 2 ... Head drive unit, 3 ... Computing unit, 4
…… Length measuring device, 5 …… Readout circuit, 6 …… Boundary detection circuit,
7 ... Demodulation circuit, 8 ... A / D converter.

Claims (1)

[Claims] 1. A boundary detecting means for detecting a boundary between a servo area and a guard band area from a servo pattern, a rough distance from the boundary to an end track to be inspected, and a track interval over the entire track area to be inspected. Of the length measuring device, a means for moving the servo signal reading head from the boundary to the vicinity of the outermost track while reading the output value of the length measuring device, and the servo signal reading head of the length measuring device. A means for moving about one track while reading the output value, a demodulation circuit for producing a head positioning position error signal from the servo pattern signal read by the servo signal read head, and a head positioning position error signal for minimizing the position error signal. A servo signal writing device, comprising means for moving a servo head and positioning the read head.