JPH03272066A - Method and device for writing servo-track - Google Patents

Abstract

PURPOSE:To write the servo-track of a high quality by detecting the displacement amount of a head by an output of an acceleration sensor installed in the vicinity of the head, while the servo-track is written, and driving a head carriage in accordance with its displacement amount. CONSTITUTION: While a servo-track 19 is written, the displacement amount of a head 21 is detected by an output of an acceleration sensor 40 installed in the vicinity of the head 21, and in accordance with its displacement amount, a head carriage 20 is driven. In this case, since a comparatively small acceleration sensor 40 is used, the acceleration sensor 40 can be installed in the vicinity of the head 21, and minute vibration of the head 21 can be detected. In such a way, the servo-track of a high quality can be written.

Description

[Detailed Description of the Invention] [Summary] Regarding a method and device for writing servo tracks on a disk, the object is to provide a method and device capable of writing high-quality servo tracks. In this method, a servo track is written on a desired concentric circle of a disk using a movably supported head. While writing a servo track, the displacement of the hexagon is determined by the output of an acceleration sensor installed near the head. The head carriage is configured to detect the amount of displacement and drive the head carriage according to the amount of displacement.

[Industrial application field]

The present invention relates to a method and apparatus for writing servo tracks on a disk, and relates to a method and apparatus for writing servo tracks in, for example, a magnetic disk device.

The servo track is used for on-track control that causes the servo head to follow a target servo track, and for seek control that moves the servo head to the target servo track. In recent years, with the increase in recording capacity, the distance between servo tracks has become narrower, so it is desired to write servo tracks with high precision.

[Conventional technology]

Servo tracks of a magnetic disk drive are generally written using a dedicated servo writer device or using the magnetic disk drive's own head. The case where a servo track is written using the magnetic disk device's own head will be described below.

First, the configuration of the magnetic disk device will be explained using FIG. 5. The spindle 10 is formed by laminating a plurality of discs 11, and has a plurality of data surfaces 111 and at least one servo surface 112. The head carriage 20 supports a plurality of heads 21 via a spring arm 23 at the tip of a head arm 22, and a carriage motor 24.
It is configured to rotate in the radial direction of the disk 11. Further, the plurality of heads 21 is a data head 211
and a servo head 212, which are arranged on the data surface 111 and the servo surface 112.

Next, servo track writing will be explained using FIG. 6. Although the spindle 10 and head carriage 20 are simplified in the figure, they are the same as those shown in FIG. 5.

In the figure, 30 is a laser length measuring machine, and the head carriage 2
The angular position of the head; 1-year ridge 20 is measured by measuring the distance from the corner cuf 31 mounted on the head; The carriage angle error detection circuit 31 is
Head carriage 2 measured by laser length measuring machine 30
0 and a target carriage angle instructed by a microprocessor (hereinafter abbreviated as MPtJ) 90,
The difference is sent to the carriage motor drive circuit 62 as a carriage angle error signal. The carriage motor drive circuit 62 drives the carriage motor 61 so that the carriage angle error signal becomes zero.

The MPU 90 performs various controls, including controlling the positioning of the head carriage 20, controlling the rotation of the spindle IO, and controlling writing of the servo truck.

The servo track writing step will be explained below with reference to FIG. For example, suppose that 1000 servo tracks are written from the outermost to the innermost of the disk 11. First, M P (J 90) advances the target and orientation angle signals so that the head 21 is located at the outermost position.

After the head 21 is positioned at the target outermost position, the head 21 is controlled so as not to deviate from that position.

Next, the MPU 90 operates the servo i/rank edge circuit 91
When servo track writing is commanded, the servo track writing circuit 91 records the servo track using the hemlock 121. When the writing of the outermost servo track is completed, the MPU 90 sends out a target carriage angle value shifted by one track, and positions the head 21 at a position shifted by one track from the outermost servo track.

Similarly, servo tracks are recorded while moving the head 21 one track at a time until the innermost servo track is recorded.

[Problem to be solved by the invention]

However, if a very small vibration is applied to the head carriage 20 from the outside and the head 21 vibrates, the servo track 19 may be recorded without the displacement of the head 21 being detected by the laser length measuring device 30. The servo track 19 does not follow a normal circular trajectory, but a slightly wavy circular trajectory.

If on-track control is performed on such a servo track, the servo head will follow the servo track that is not normal, and the data head may pick up the signal from the adjacent data trunk, which may prevent data playback from occurring properly. be. Furthermore, as recording capacity increases in the future, it is expected that the track spacing will become narrower, and the above-mentioned problem will become even more serious.

Therefore, in order to solve the above-mentioned problems, it is an object of the present invention to provide a servo track writing method and apparatus capable of writing high-quality servo tracks.

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, 11 is a disk on which a servo track 19 is recorded, and 20 is a head carriage that supports a head 21 for recording the servo track and positions the head 21 on a desired concentric circle of the disk 11.

30 is a carriage position detection means for detecting the position of the head carriage 20, and 31 is a carriage position error detection circuit for outputting the difference between the carriage position detected by the means 30 and the target carriage position.

40 is an acceleration tensor provided near the head 21, and 41 is a head displacement detection circuit that detects the displacement of the head 21 from the output of the sensor 40.

Reference numeral 50 selects the output of the carriage position error detection circuit 31 when the head 21 is positioned on a desired concentric circle of the disk 11, and selects the output of the head displacement detection circuit 41 when the head 21 records the servo track 19. It is a means.

60 selects Hen 1 according to the signal selected from the selection means 50.
' This is a carriage driving means for driving the carriage 20.

[Function] Measuring head displacement using a conventional laser length measuring device requires an optical reflection means, so it was not possible to mount a relatively large reflection means near the hem 1'. However, the structure of the present invention According to the method, since a relatively small acceleration sensor 40 is used, the acceleration sensor 40 can be installed near the head 21, and minute vibrations of the head '21 can be detected.

(Embodiment) Fig. 2 is a diagram for explaining servo track writing according to the present invention.In the figure, the same parts as shown in Fig. 6 are given the same numbers.

The difference from the conventional technology in FIG. 2 is that the acceleration sensor 4
1. A head displacement detection circuit 42 and a selection circuit 50 are added. The processing steps of the MPLJ90 that controls servo track writing are also different.

First, the acceleration sensor 40 is a well-known device that includes a piezoelectric element and a weight inside the sensor, and detects the inertial force of the weight by changing the potential of the piezoelectric element. Acceleration sensor 40
There is a small size, for example, 1 mm thick and 2 mm square, which can be attached to the spring arm 23 as shown in FIG.

The head displacement detection circuit 41 integrates the acceleration of the head 21 output from the acceleration sensor 40 twice, thereby
The amount of displacement of the head 21 is calculated.

The selection circuit 50 selects either the carriage angle error detection circuit 31 or the head displacement detection circuit 4 based on the selection signal from the MPU 90.
1 is selected and output to the carriage motor drive circuit 62.

Next, the mounting position of the acceleration sensor 40 will be explained in detail using FIG. 4. In the figure, a head carriage 20 supports the head via a spring arm 23 at the tip of a head arm 22. As shown in FIG. The head is composed of a plurality of data heads 211 and one servo head 212. Acceleration sensor 40 is attached to spring arm 23 that supports servo head 212.

Next, the servo track writing operation will be explained using FIGS. 2 and 4. First, the selection circuit 50 selects the output of the carriage angle error detection circuit 31 and sends it to the carriage motor drive circuit 62.
A target carriage angle signal is sent to the carriage angle error detection circuit 31 so as to position the carriage angle on track O.

When the target carriage angle signal is switched, a difference occurs between the actual carriage angle measured by the laser length measuring machine 30 and the target carriage angle instructed by the MPU 90, as shown in the carriage angle error signal. The carriage motor drive circuit 62 drives the carriage motor 61 so as to make the carriage angle error signal zero.

After a predetermined time has elapsed since the target carriage angle was switched, the MPU 90 switches the selection signal so that the selection circuit 50 outputs the human power from the head displacement detection circuit 41 to the carriage motor drive circuit 62. As a result, the head carriage 20 is controlled to zero the displacement of the head 21 detected by the acceleration sensor 40, and starts recording the servo track signal.

When the recording of the servo track signal is completed, the MPU 90 switches the selection signal to the selection circuit 50 so that the human power from the carriage angle error detection circuit 31 is output to the carriage drive circuit 62. In response to this, M1''U3O sends a target carriage angle signal for positioning the head 21 to track 1 to the carriage error detection circuit 31 in order to record the servo 1 to rack signals on the adjacent track 1.

Thereafter, servo tracks are sequentially written onto the disk 11 in the same manner.

As explained above, in this embodiment, since the acceleration sensor is installed near the head, the displacement of the head can be detected more accurately, and the position of the head is controlled according to the head displacement, thereby improving quality. It becomes possible to write high servo tracks.

Furthermore, in the embodiment, servo control of the head position is performed by selecting either the head position detected by the laser length measuring machine or the head position detected by the acceleration sensor, but it is not possible to use both at the same time. The servo control of the spatula 1 position may be performed by.

〔Effect of the invention〕

According to the present invention, since the spatula I/position is servo-controlled by the acceleration sensor provided near the head as explained in the above embodiment, the displacement of the head can be detected more accurately, and high-quality servo control is performed. Tracks can now be written.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a diagram explaining servo track writing according to the present invention, FIG. 3 is a diagram explaining the mounting position of the acceleration sensor, and FIG. 4 is a diagram explaining the mounting position of the acceleration sensor. is a time chart explaining the operation of FIG. 2, FIG. 5 is a configuration diagram of a magnetic disk device, and FIG. 6 is a diagram explaining conventional servo truck writing. In the figure, 1 0 1 0 1 0 1 0 0 disk'\tsu1'carriage'\rad) - Jarringe position detection means Carriage position error detection circuit Acceleration sensor Head displacement detection circuit selection Lower stage carry/nozzle drive means

Claims (1)

[Claims] [1] The disk (11) is moved by the head carriage (20).
) A method for writing a servo track (19) on a desired concentric circle of the disk (11) using a head (21) supported so as to be movable in the radial direction of the disk (11), the method comprising: , the amount of displacement of the head (21) is detected by the output of an acceleration sensor (40) installed near the head (21), and the head carriage (20) is driven according to the amount of displacement. Servo track writing method. [2] A disk (11) on which a servo track (19) is written, a head (21) that writes the servo track (19) on the disk (11), and a head (21) that moves the head (21) in the radial direction of the disk (11). a head carriage (20) that movably supports the head carriage (20), a carriage position detection means (30) that detects the position of the head carriage (20), and a carriage position error detection circuit that detects the difference between the carriage position and a target carriage position. (31), and a carriage driving means (31) for driving the head carriage (20) according to the output of the carriage position error detection circuit (31).
60), an acceleration sensor (40) installed near the head (21); and an output of the acceleration sensor (40) to cause the head (2
a head displacement detection circuit (42) that detects the displacement of 1);
When the head (21) is positioned at a desired position on the disk (11), the output of the carriage position error detection circuit (31) is selected, and when the head writes a servo track, the output of the head displacement detection circuit (41) is selected. 1. A servo track writing device comprising: a selection means (50) for selecting an output of and outputting the selected output to the carriage driving means (60).