JP2579232B2 - Servo signal writing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo signal writing device, and more particularly, to a head disk assembly (hereinafter, HD) using a servo writer.
A), the present invention relates to a servo signal writing apparatus for writing servo information by setting a track at an appropriate position by controlling a position of a magnetic head with respect to a track in writing a servo signal to a magnetic disk. .

[Prior Art] Hard magnetic disk drives used in information processing apparatuses are integrated into HDAs due to downsizing of components. FIG. 3 (a) is a perspective external view of the HDA, and FIG. 3 (b) is a plan view. In the HDA 1 shown in FIG. 1A, a plurality of hard magnetic disks (hereinafter simply referred to as magnetic disks or disks) 12 are mounted on a spindle 13 inside a housing 11 and rotated by a rotating mechanism 2. A magnetic head 14a and a support arm 14b are provided on the front and back and both sides of each disk 12,
b is attached to a common support rod 15 and rotated by the VCM drive mechanism 16, and each magnetic head 14a seeks a track on the corresponding disk surface. A positioning arm 17 is attached to the support rod 15 to limit the seek range to within the effective range of the disc 12.
However, the driving mechanism 16 is provided with an outer stopper 18a and an inner stopper 18b made of rubber. In FIG. 3B, the center of each disk 12 is O, and the radius of the outer peripheral edge Eg is Le.
The outer stopper 14a is provided at a position of the radius Lso excluding the unused ΔL from the edge Eg, and this position is set as the outermost track, and a number of tracks minute inside, for example, at a pitch p of 10 μm, for example, are provided. TR is set. Therefore, the position of the track TR is usually expressed as a distance from the center O of the magnetic disk, that is, as a radius, and the tracks are arranged at an equal pitch p in the radial direction. In data access, the computer of the magnetic disk drive reads the position data of each track stored in the memory and the magnitude and supply time of the supply voltage of the drive mechanism 16 corresponding thereto, and rotates the drive mechanism 16 accordingly. The magnetic head 14b seeks the designated track.

Now, in order to access data, it is necessary to position the magnetic head 14a at a correct position with respect to the track. For this reason, a servo system is used. There are various types of servo systems.In this case, what is called a data surface servo system, a servo signal is written in advance to a position corresponding to each track of each disk by a servo writer, and this is read out during data access. The position control mechanism causes the magnetic head to correctly correspond to the track.

FIG. 3 (c) shows a schematic structure of the writing mechanism 3 of the servo writer for the HDA1. A VCM drive mechanism 32 is fixed to the base board 31, and a drive arm 34 is attached to a rotating shaft 33 that rotates. A drive pin 35 is attached to a tip of the drive arm 33, and a mirror 36b is attached to a side surface thereof. Further, a laser distance meter 36a is fixed to the base board 31, and the movement distance of the drive arm 34 is measured by interference of the reflected light of the laser by the mirror 36b. In writing the servo signal, the HDA 1 is positioned and attached to the writing mechanism 3. The housing 11 of the HDA 1 is provided at a position corresponding to the support arm 14b as shown in FIG.
An arc-shaped cutout hole 19 is provided, through which the drive pin 35 comes into contact with the side surface of the support arm 14b. The microprocessor controls the VCM drive mechanism 32 to rotate the rotating shaft 33.
, And the magnetic head 14a seeks the specified track. The position of the magnetic head during seek is measured by a laser range finder, and when it is confirmed that the position of the magnetic head has reached a predetermined track position, the drive mechanism 32 is stopped, and a servo signal is applied to the sought track by a servo writer. Is written.

[Problem to be Solved] In the above writing, the position L of the outer stopper 18a
The standard position of each track is set in advance with e as a starting point, stored in a memory, and read out to control the position of the magnetic head 14a, but there is a problem with the position of the outer stopper 18a provided on the HDA1. There is. That is, the stopper 18
The attachment of a and 18b is performed in the assembling work of the HDA 1, and when the work is completed, the lid is attached to the housing 11, and thereafter, it is basically unnecessary to rework the inside. However, the mounting positions of the stoppers 18 are not particularly accurate and vary considerably, and are elastic due to rubber. Stopper 18 if more severe
a or 18b is missing. With these, the magnetic head
It is inevitable that the stop position of 14a will be uncertain. As described above, the starting position of the operation of the magnetic head is
The position where the magnetic head comes into contact with the outer stopper 18a is determined. When the magnetic head stops moving outside this position, the access operation becomes defective. On the other hand, the standard position preset in the servo writer does not match this contact position. The reason is that, even if the target position is set as the radius Lso, at least the maximum variation value should be set to the position of the target position Lso because the mounting position of the stopper 18a that determines the outermost track varies. Otherwise, the unused area ΔL cannot be secured. Therefore, the average position of the stopper 18a is inside the radius Lso which is the target position shown in FIG. 3 (b). Therefore, the actual outermost track after the stopper 18a is attached is located inside the target position. As a result, when the position of the radius Lso, which is the target position, is set as the outermost track, and the servo signal is written at each track position with reference to the outermost track, the write position of the servo signal becomes defective. Therefore, there is a need for a method of accurately detecting the contact position, calibrating the standard position stored in the memory, and writing a servo signal to the calibrated position. In the above, the mounting position of the inner stopper 18b does not matter because there is a certain margin.

The present invention has been made in view of the above, and by detecting a contact position between a magnetic head and a stopper, it is possible to calibrate data of a preset standard position for each track. It is an object of the present invention to provide a servo signal writing device capable of writing a servo signal at a correct position.

[Means for Solving the Problems] The features of the servo signal writing apparatus of the present invention for achieving the above object include a magnetic disk, a magnetic head, and a seek range of the magnetic head limited to an effective range. A laser rangefinder that engages with the support arm of the magnetic head and moves the support arm to measure the movement distance of the support arm with respect to the head disk assembly having the stopper accommodated in the housing. In a servo signal writing device that moves the magnetic head to a predetermined position in the radial direction by moving the support arm and writes servo information on a predetermined track, a VCM that moves the support arm
A drive mechanism, a voltage detector for detecting a VCM drive voltage of the VCM drive mechanism, control means for moving the support arm in the track direction of the outermost track of the magnetic disk, and a voltage for moving the support arm by the control means. The track position in the radial direction of the magnetic disk is calculated based on the moving distance obtained by the laser distance meter at the time when the detection voltage of the detector suddenly rises, and the stopper position of the stopper measured in advance from the calculated track position is calculated. Outermost track position calculating means for calculating the position in the radial direction obtained by subtracting the return amount of the magnetic head in the radial direction due to elasticity as the outermost track position, and calculating the outermost track position by the outermost track position calculating means. Writes servo information to each track based on this position as the outermost track position A.

More specifically, the magnetic head is moved by controlling the VCM driving mechanism with a target of a standard position stored in the memory in advance with respect to the track set on the outermost circumference of the magnetic disk. It monitors the supply voltage to the VCM drive mechanism during movement, and measures the moving distance of the magnetic head using a laser range finder. The contact position between the stopper and the magnetic head is obtained by subtracting the previously measured return amount of the magnetic head due to the elasticity of the stopper from the measurement distance of the laser distance meter when the supply voltage suddenly increases and reaches the peak value. Is calculated. The standard position of all the tracks including the outermost track stored in the memory is calibrated using this as a write position of the servo signal for the outermost set track. A servo signal is written to each calibrated position by a servo writer.

[Operation] In the servo signal writing device described above, the magnetic head is moved by the VCM drive mechanism with the target of the standard position with respect to the track set at the outermost circumference, which is stored in the memory in advance. The supply voltage to the VCM drive mechanism, which is monitored during this movement, detects a point in time at which the supply voltage suddenly rises and reaches a peak value.From the measured distance of the laser distance meter at this point, the elasticity of the stopper measured in advance is used. The contact position between the stopper and the magnetic head is calculated by subtracting the return amount of the magnetic head. This is the write position of the servo signal for the track set on the outermost circumference of the magnetic disk, and when the standard position of all the tracks stored in the memory is stored, the track set as the outermost circumference is They can be calibrated based on position. Therefore, in writing the servo signal in this case, each track is correctly positioned by the calibration position, and the servo signal is written to each track by the servo writer.

[Embodiments] FIGS. 1A, 1B and 1C are block diagrams of a main part of a servo writer and a method of detecting a contact position in an embodiment of a servo signal writing apparatus according to the present invention. , And a table of standard positions and calibration positions stored in memory.

In FIG. 1A, reference numeral 3 denotes a writing mechanism of the servo writer shown in FIG. 3C, and a signal processing unit 4 is provided for the writing mechanism. In the signal processing section 4, data of the standard position for each track is stored in a memory (MEM). Prior to writing the servo signal, the microprocessor (MPU) 41 reads data at a standard position with respect to the outermost track, and the VCM control circuit 43
Is sent out. This allows the supply voltage to be
The rotation shaft 33 rotates by being supplied to the VCM drive mechanism 32, and the magnetic head 14a moves as described in FIG. 3 (c). During this movement, the supply voltage is monitored by the VCM voltage detection decision 44, and the monitoring data is digitized by the A / D converter 45 and transferred to the MPU 41. At the same time, support arm 36b
The moving distance of the mirror 36b attached to the
The measured data is digitized by the A / D converter 46, transferred to the MPU 41, and converted into a moving distance of the magnetic head 14a by an appropriate arithmetic expression. Now, the positioning arm 1 provided on the HDA 1 by moving the magnetic head 14a.
7 comes into contact with the outer stopper 18a (refer to FIG. 3 (a) or (b)).
Due to the inertia of 5 and the elasticity of the rubber of the stopper 18, the surface of the stopper 18a and the positioning arm 17 are pressed into the rubber to some extent and then returned to the contact position and stopped. The position where the positioning arm is press-fitted is measured by the laser distance meter 36a. The point of the present invention is to measure the press-fit position. In other words, the above operation of the positioning arm limits the sudden increase in the supply voltage to the VCM drive mechanism. In (b), the horizontal axis represents the moving distance L of the head, and the vertical axis represents the VCM voltage ( Supply voltage) e. Generally, when the magnetic head is moved and stopped at a predetermined position, a method is used in which the speed is gradually increased in the initial stage, and when the speed becomes constant, the speed is maintained until the stop position, and the speed is gradually reduced to stop. . To this end, the supply voltage e has a constant value e ₀ (b) following the rising curve (a) as shown in FIG.
Control is performed as shown in FIG. Now, assuming that the contact position between the positioning arm 17 and the stopper 18a is La, the pressure required to press the arm against the elasticity of rubber requires more pressure than before, and the supply voltage e rises rapidly. Thus, a curve (d) having a peak value em is obtained. Thereafter, the supply voltage is continued (e) unless the supply voltage is stopped, or the voltage is reduced to drop as shown in (f). Incidentally, when the stopper 18a is missing, because the fixed value e ₀ followed can thus detect missing. As described above, it is assumed that the positioning arm 17 is press-fitted into the stopper 18a and the inside when the supply voltage reaches the peak value em. This press-fit position is measured by a laser distance meter,
It is converted to the moving distance Lb of the magnetic head. Thereafter, the magnetic head is restored to the contact position (distance La) by the elasticity of the stopper. This return amount is Lc shown. As mentioned above,
It is necessary to write the servo signal for the outermost track at the contact position La. However, since La has not been determined yet, the return amount Lc is obtained in advance by actual measurement, and this is subtracted from Lb to obtain the contact position La. Since the elasticity of rubber varies, and the pressing force of the positioning arm 17 is not strictly constant, actual measurement is performed for an appropriate number of HDAs.
It is necessary to find the average value of c.

The detection of the contact position described above is applied to FIG. VC
The output voltage of the M voltage detector 44 is monitored by the MPU 41. When the output voltage reaches the peak value em, the data of the distance Lb measured by the laser distance meter 36a is input to the MPU 41 and temporarily stored in the memory 42. The return amount LC measured in advance and stored in the memory 42 is subtracted from Lb by the MPU 41 to obtain the contact position La.

FIG. 1C shows a table of the standard position distance (standard distance) Ls stored in the memory 42 in advance and the calibration position distance (calibration distance) Ls' obtained by calibrating the standard position distance. The standard distance Ls is a radius as viewed from the center of the disk 12, similarly to the radius Lso as the target outermost track position shown in FIG. 3 (b). This radius is mirror 3 by laser rangefinder 36a.
It is calculated by the MPU 41 based on the distance Ld (see FIG. 1A) from the laser range finder 36a to the arm 14b measured via 6b. Here, it is assumed that the outermost track number is 0, and the standard distance to this is Lso. Actually H
The standard distance Lso of the track number “0” set in the DA is slightly inside the distance Lso set as the target shown in FIG. 3 (b). The reason for this is that, as described in the prior art, the maximum variation value is determined because the mounting position of the stopper 18a that determines the outermost track varies with the radius Lso of the target position (see FIG. 3B). This is because the average position of the stopper 18a is set inside the radius Lso, which is the target position, in order to make this position. Therefore, the standard distance of the actual track number “0”
Lso is determined by the position of the stopper 18a set each time, and becomes the position of La inside the radius Lso of the target position, as shown in FIG. 1 (b).

The horizontal axis in FIG. 1 (b) is the track position.
The radial distance (radius) from the center O of the disk 12 is shown, but is omitted in the middle. Accordingly, actually, La, which is the position of the standard distance Lso of the track number “0” actually set to the radius Lso of the target position shown in FIG. 3B, is an extremely close position.

Now, since each standard distance Ls represents a distance from the center O of the disk 12, that is, a radius, each track is
Assuming that the tracks are arranged at a predetermined pitch with respect to the center O of the disk 12 and the pitch between the tracks (the distance from the center of the track to the center of the next track) is p, Ls ₁ for the track of No. 1 L is subtracted from p (added depending on the position of laser distance detection), and similarly, LsN for the final number N is Lso-Np. On the other hand, the calibration distance Ls' is La for the number 0, and is obtained by subtracting p by multiplying it by the track number, and the table is rewritten.

FIG. 2 is a schematic flowchart showing the procedure of detecting the contact position and calibrating the standard position. When the servo writer starts, the MPU 41 uses the VCM control circuit 43
Is activated and the magnetic head moves with respect to the standard distance Lso, and in parallel with this, the moving distance of the head is measured by the laser distance meter. When the monitored VCM voltage e reaches the peak value em (yes), the head distance Lb at this point is measured and stored in the memory. Then MPU4
The contact distance La = Lb−Lc with respect to the contact position is calculated by 1 and the standard distance Ls in the memory table is calibrated and rewritten to the calibration distance Ls ′. The calibration distance Ls 'is read by the MPU 41, and based on the calibration distance Ls', the support arm 14b of the magnetic head 14a is driven by the VCM drive mechanism 32 via the drive arm 34, as described above in the related art. To seek. During this seek and the magnetic head 14a
Is measured by the laser distance meter 36a from the measurement distance Ld. Then, the magnetic head 14a is positioned at a position where the distance on the radius of the magnetic disk 12 calculated from the measured distance L becomes the calibration distance Ls ', and the respective calibration distances Ls' (L
a, La−p, La−2p,...) are written to each track.

[Effects of the Invention] As is apparent from the above description, in the servo signal writing device according to the present invention, when the positioning arm comes into contact with the stopper, the voltage supplied to the VCM drive mechanism sharply rises and peaks. Focusing on indicating the value, the return amount of the magnetic head due to the elasticity of the rubber of the stopper measured in advance is subtracted from the position of the magnetic head at the time when the supply voltage reaches the peak value, and the difference between the stopper and the magnetic head is determined. The contact position is calculated, and the outermost track is set as a correct position for the outermost track. Thereby, for example, it is possible to calibrate the standard positions of all the tracks stored in the memory, and by performing such calibration, the servo signal can be correctly written by the servo writer. There is a great effect that a correct servo signal can be written to each track regardless of the position of the stopper.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) show a block diagram of a main part of a servo writer, a curve diagram of a VCM supply voltage, and a memory in an embodiment of a servo signal writing apparatus according to the present invention. FIG. 2 is an explanatory view of a table of stored standard distances and calibration distances, FIG. 2 is a flowchart for each figure in FIG. 1, and FIGS. 3 (a), (b) and (c) are perspective external views and plan views of HDA. FIG. 2 is a diagram and a structural diagram of a writing mechanism of a servo writer corresponding thereto. 1 Head disk assembly (HDA), 11 Case, 12 Magnetic disk, 13 Spindle, 14a Magnetic head, 14b Support arm, 15 Support rod, 16 VCM Drive mechanism, 17 Positioning arm, 18 Stopper, 19 Notch hole, 2 Rotation mechanism, 3 Writing mechanism, 31 Base board, 32 VCM drive mechanism, 33 Rotation Axis, 34: Drive arm, 35: Drive pin, 36a: Laser rangefinder, 36b: Mirror, 4: Signal processor, 41: Microprocessor (MPU), 42: Memory (MEM), 43 VCM control circuit, 44 VCM voltage detector, 45, 46 A / D converter, ... Step numbers in flowchart.

Claims (1)

(57) [Claims] 1. A magnetic disk, a magnetic head, and a head disk assembly including a stopper for limiting a seek range of the magnetic head within an effective range in a housing. A laser rangefinder that engages and moves the support arm to measure the movement distance of the support arm, and moves the magnetic head to a predetermined position in the radial direction by moving the support arm. A servo signal writing device for writing servo information to a track,
An M (voice coil motor) drive mechanism, a voltage detector for detecting a VCM drive voltage of the VCM drive mechanism, and control means for controlling the movement of the support arm toward the outermost track of the magnetic disk; Calculating a track position in the radial direction of the magnetic disk based on the movement distance obtained by the laser distance meter at the time when the detection voltage of the voltage detector sharply rises when the support arm is moved by the control means; An outermost track position calculating means for calculating a position in the radial direction obtained by subtracting a return amount of the magnetic head in the radial direction due to the elasticity of the stopper measured in advance from the calculated track position as an outermost track position; The position calculated by the outermost track position calculating means is stored in the outermost track position. Servo signal writing device that writes servo information to each track based on this as a reference position.