JPH01159875A - Method for displaying tracking error for magnetic disk driver - Google Patents

Abstract

PURPOSE:To make it easy to understand the factor of an off-track by reading a reference adjusting signal recorded onto an alignment disk, measuring an off-track quantity corresponding to the exciting phase of a stepping motor and expressing a chucking error etc., by means of the lengths of the side and the form of a polygon. CONSTITUTION:A carriage 28 is reciprocated in a track diameter direction from an error circumference side to an output circumference side and from the outer circumference side to the inner circumference side by the driving part of a magnetic disk driver which is an object to be checked. The reference adjusting signal of a track corresponding to a stepping motor 25 exciting phase of the driving part is read by a magnetic head 29 over each 1 cycle of the alignment disk chucked by a chucking device 32, and the off-track quantity in each track is measured. A display calculates the eccentric error and hysteresis error of each track in the classified moving direction of the carriage 28 from such measuring data, and the display displays the errors for each track in making them into the lengths of the side and the form of the polygon. Thus, the each factor of the off-track can be made easy to visually understand.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a tracking error display method used when inspecting a track radial positioning error of a carriage drive section of a magnetic head of a magnetic disk drive device, and in particular, The present invention relates to a tracking error display method suitable for tracking error inspection of a high-density magnetic disk drive device.

[Conventional technology]

A conventional tracking error display method for a magnetic disk drive is as described in Japanese Patent Publication No. 59-7142, in which an adjustment signal of an alignment disk on which marking marks and a track radius position adjustment signal are recorded is transmitted to a magnetic head of a magnetic disk drive. This was done by reproducing the data and displaying it on an oscilloscope, and it was possible to display positioning errors in the track radial direction.

However, although it is possible to determine the size of a positioning error using an oscilloscope display, it must be determined accurately by calculation, and it is not possible to display all factors of the positioning error at once.

Another conventional example will be explained using FIG.

On the alignment disk 1, a track diameter adjustment signal 36 is sent to a track in the center, and a diameter that is a specified dimension from the center axis 39 of one rotation [= O, l nll + eccentricity and larger than the reference diameter by approximately δ/2 = 0.075IIn] is set on the center track. A large signal 37 and a small diameter signal 38 smaller by the same size are provided, and a method of detection using a signal called a so-called cat's eye is used. The same signal is also written on the back side of the alignment disk 1, so that the positioning error in the track radial direction can be measured for the upper and lower two heads.

As shown in FIG. 9, the actual measurement method is to insert the alignment disk 1 into the magnetic disk drive device 2, move the carriage to a specific track, reproduce the track diameter adjustment signal 36, and send this signal to the oscilloscope 40. This is done by displaying the

With this method, it is possible to display the positioning error of the magnetic disk drive, but the resolution is low when verifying the tracking error using the cat's eye signal. It has been difficult to guarantee data compatibility with magnetic disk drives.

Furthermore, it was not possible to measure and display the rechatting error based on the form of the signal.

Here, data compatibility of high-density magnetic disk drives will be explained. Since multiple magnetic disk drives record and reproduce data via removable magnetic disks, the difference between the specified track radial position and the position In where the actual magnetic disk drive and magnetic head are positioned. (hereinafter referred to as off-track) as the main cause.

(1) After assembling the magnetic disk drive, the positional adjustment of the carriage occurs when adjusting the magnetic head so that it is below the specified off-track amount! j1.1 difference, (2) Carriage positioning error due to manufacturing accuracy of the transmission system.

(3) Chucking error that occurs when chucking a magnetic disk to a magnetic disk drive device.

(4) Differences in expansion and contraction between the magnetic disk and the magnetic disk drive due to temperature and humidity.

is raised.

Here, 96TPI magnetic disk 9. The above-mentioned off-track tolerance values for the dynamic head are R/W gear width W of the magnetic head = 165 μm, and erase core width E.

; It is related to 100 μm and is known to be 50 μrn. Therefore, (1) of L for this 50 μrn
Although it is necessary to allocate one error item from (4) to ensure data compatibility, the difference in expansion and contraction due to temperature and humidity (4) is largely influenced by the physical properties of the material and is difficult to reduce.

Therefore, an analysis of (1) to (3) results in the following.

(1) The carriage position adjustment error is closely related to the adjustment time, and to suppress the error, the adjustment time will be significantly extended.

(2) The carriage positioning error is thought to be caused by the static angle error of the stepping motor itself, which is the drive source, and the transmission system error, but in high-density magnetic disk drive devices, the stepping motor and transmission system have manufacturing precision. It has reached its limit, and any attempt to further improve accuracy will result in increased costs and unstable quality due to poor yield.

(3) The main cause of chucking error is the accuracy of the chucking parts of the magnetic disk and magnetic disk drive.
Similar to (2), the required accuracy improvement in high-density magnetic disk drives has also reached its limit.

[Problem that the invention seeks to solve]

With the above conventional technology, the accuracy required for each component has reached its limit as the density of magnetic disk drives increases, and the cost increases to ensure data compatibility between multiple magnetic disk drives. Improved accuracy required for each component, leading to
Alternatively, it is necessary to take measures to improve the accuracy of carriage position adjustment, which increases assembly adjustment time, which poses a problem in terms of productivity improvement and reliability improvement.

The purpose of the present invention is to inspect the accuracy of each component that occurs in a probability distribution during assembly of each magnetic disk drive using an alignment disk, and to visually detect each factor of off-track. It is an object of the present invention to provide a tracking error display method that facilitates the verification of positioning errors in magnetic disk drives by making it easy to understand, and has excellent productivity and reliability.

[Means for solving problems]

The above object is to provide a chucking device for grasping a magnetic recording medium, a magnetic head for recording or reproducing data on the magnetic recording medium, a carriage for mounting the magnetic head, and a chucking device for moving the carriage onto a track on the magnetic recording medium. In a tracking error display method when inspecting a magnetic disk drive device having a drive section that moves in a radial direction, a number of concentric reference adjustment signals corresponding to the excitation phase of a stepping motor of the drive device is recorded. Calculating the reference adjustment signal input to the alignment disk and the magnetic head;
The off-track amount, which is the amount of deviation of the magnetic head with respect to a predetermined position in the track radial direction, is measured by reading out the reference adjustment signal with the magnetic head over one revolution each, using a display device to display the off-track amount. A chucking error of the chucking device for each direction of movement of the carriage and a hysteresis error depending on the direction of movement of the carriage are calculated from the track amount, and each error is calculated based on the length of the side of the polygon for each track of the reference adjustment signal. This is achieved by displaying the image in terms of shape and shape.

[Effect]

The carriage is reciprocated from the inner circumferential side to the outer circumferential side and from the outer circumferential side to the inner circumferential side in the track radial direction by the drive unit of the magnetic disk drive device to be inspected, and the yjA of the alignment disk chucked by the chucking device is By reading out the reference adjustment signals of the tracks corresponding to the excitation phases of the stepping motor of the moving part over one rotation using a magnetic head, the amount of off-track in each track corresponding to each phase of the stepping motor of the driving device is measured and displayed on one display. calculates the chucking error of each track for each direction of carriage movement, that is, the eccentricity error, and the hysteresis error due to the carriage movement direction from this measurement data,
These errors are displayed for each track as the side length and shape of a polygon.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9.

First, the structure and operation of a magnetic disk drive device for verifying off-track will be explained with reference to FIG. The magnetic disk 24 is chucked by a collet 32 to a rotating bearing portion of a direct drive motor (hereinafter abbreviated as DD motor) 33, and is rotated by the DD motor 33 at a constant speed. The carriage 28 carrying the magnetic head 29 can be moved in the track radial direction by the stepping motor 25.

The magnetic disk 24 is positioned to the target track and data is recorded and reproduced on the magnetic disk 24.

Here, to explain the head image determining mechanism, first, the rotation angle of the stepping motor 25 fixed to a chassis (not shown) changes in a stepwise manner in response to a control signal. Then, the carriage 28 is linearly moved along the rail 35 via the steel belt 26 wound α around the pulley 27. Therefore, the magnetic head 29 mounted on the carriage 28
In response to the rotation of the stepping motor 25, the magnetic disk 24 also performs linear motion at regular intervals on the magnetic disk 24. By setting this interval to the interval between tracks, the magnetic head 29 is positioned at the position of the track. Also.

The index timing light emitting unit 3 detects the index timing, which is the reference position in the rotational direction of the magnetic disk 24.
0 and the index timing light receiving section 31.

Positioning error factors caused by such a magnetic head positioning mechanism include (1) a static angle error of the stepping motor 25 and a hysteresis error that changes depending on the load in the rotational direction, and (2) an eccentric component that occurs when chucking the magnetic disk 24. (3) vertical assembly error due to the assembly accuracy of the magnetic head 29, etc.

A data input device for measuring and displaying off-track in order to ensure data compatibility of the above-mentioned magnetic disk drive device will be explained with reference to FIG.

First, the alignment disk 1 on which the track radial adjustment signal is recorded is placed on a predetermined track by the magnetic disk drive device 2.
Insert into. A sequence of moving the carriage 28 from the inner circumference to the outer circumference and from the outer circumference to the inner circumference, and the reference outermost circumference 1 to After moving the magnetic head 29 to the alignment disk 1, the magnetic head 29 is moved to a specified track on which the track diameter adjustment signal is recorded. In this track, the track diameter adjustment signal is regenerated and converted into a DC voltage including ripples in a rectifier circuit 3, and the high frequency ripples are removed by a filter 4. The output of this filter 4 is digitized by an A/D converter 5, and
The data is taken into the memory of the personal computer 7 via 106. After that, the amount of off-track is calculated using the data in the memory.

Next, the magnetic head 29 is moved further to the inner circumference of the alignment disk 1 and the same process is performed. Similarly, the remaining 1-
After data is captured by the rack, the direction of movement is changed again, the magnetic head is moved from the inner circumference to the outer circumference, and the same processing is performed. When data acquisition and processing on a predetermined track are completed, the vertical deviation of the magnetic head, the static angle error of the stepping motor 25, the hysteresis error due to the rotational direction of the stepping motor 25, etc. are displayed on the screen of the personal computer 7.

An example of the alignment disk 1 to be removed is shown in FIG. A track diameter adjustment signal 16 is applied to the alignment disk 1 by adjusting track centers 11 corresponding to each phase with the same number of phases as the stepping motor (four phases in this embodiment).
It is located on 12, 13, and 14. Furthermore, the same signal as above is written on the back surface of the alignment disk 1.

On each adjustment track center 11 to 14, a track diameter adjustment signal 16 is provided as a pair of inner circumference signal 17 and outer circumference signal 18 which extend geometrically alternately from the adjustment track center 11 to 14 to the inner circumference side and the outer circumference side. A total of eight pairs are provided symmetrically with respect to the rotation center axis 9.

Here, the static angle error of the stepping motor 25 is the fourth
As shown in the figure, an error curve appears with one period having the same number of steps as the number of phases (four phases in this embodiment) of the stepping motor 25, and it is generally known that the error between the same phases is small. In FIG. 4, each phase is indicated by o, x, or 62 symbols. Therefore, in order to determine the rest angle of the stepping motor 25, the alignment disk 1 shown in FIG.
Adjustment track centers 11 to 14 of stepping motor 2
They may be arranged in correspondence with each of the five phases. In this example, 1
- Rack Nα was set at 16, 19, 22.25.

Next, align the magnetic disk drive with alignment disk 1.
5 shows, for example, the track diameter adjustment signal 16 reproduced by the magnetic head 29 on the track Nα 25 corresponding to the adjustment track 14 and the output of the filter 4 shown in FIG. 2.

Here, (a) shows the playback signal of the upper head, (b) shows the filter output signal of the upper head, (Q) shows the playback signal of the lower head, and (d) shows the filter output signal of the lower head. The signals (VRUA, VRLA, etc.) correspond to values taken into the personal computer 7 by the A/D converter 5 in FIG.

From these values, each off-track factor can be determined as follows.

(1) Static angle error ΔL, Δ of stepping motor 25
U has 8 pairs (7) (VRLA) i / (VRL
B) The value of i and (VRUA)j/(VRUB)j,
The R/W gap width W of the magnetic head 29 can be expressed as follows.

(2) Since the hysteresis error is the difference in the static angle error of the stepping motor 25 depending on the carriage feeding direction, it can be easily determined from (1).

(3) The vertical assembly error of the magnetic head 29 is calculated from ΔL−ΔU.

(4) 8 pairs per circumference of the magnetic head 29 (7) (VRLA)
i / (Vui, n) i or (VRUA) j
/ (VRUB) j (7) From the difference between the maximum value and the minimum value of the ratio, the chucking error α, which is the error of the eccentric component that occurs when chucking the magnetic disk 24, can also be determined as follows.

Next, the off-track calculated using the above method.

An embodiment of the present invention that is collectively displayed on the screen of the personal computer 7 shown in FIG. 2 will be described with reference to FIG. 6.

In FIG. 6, al''-'aδ is track NQI 6
The off-track at 19.22.25 is shown, a1 to a4 are the errors of the lower head, and a5 to a6 are the errors of the upper head. Further, the left side Q1 of each square represents the error when moving in the inner circumferential direction, and the right side Q2 represents the error when moving in the outer circumferential direction.

Here, (1) The chucking error 2α is expressed by the length of Ql or Q2, and the longer the length, the larger the chucking error.

(2) Hysteresis error is expressed by the length of flasinθ. To be precise, it is the difference in the static angle error of the stepping motor 25 depending on the carriage feeding direction as described above, but basically the chucking error does not change depending on the carriage feeding direction, so the line segment QhkQz indicating the chucking error It is equivalent to the sine component of Q, 3, which connects .

(3) The vertical assembly error of the magnetic head 29 can be ascertained from the difference between nl and a6 of the same I/rack, for example, track Nα16.

(4) The variation in the static angle error due to the excitation phase of the stepping motor can be understood from the positional relationship of a 1 '' a 4.

As described above, among the errors represented by the eight rectangles, the maximum point b1 and the minimum point b2 represent the off-track of the magnetic disk drive unit. Therefore, the maximum point b1 and the minimum point b2 are the allowable value Q4. If it is within Q3, data compatibility can be guaranteed in the magnetic disk drive.

Next, a case where the off 1-rack is not within the allowable value will be explained using FIG. 7.

In this case, the cause of off-track occurrence is investigated. (1) As shown in (a), if Ql and Q2 of each rectangle a1 to a6 are long, the chucking error is large, so magnetic Collet 32 and direct drive motor 33 shown in FIG. 1 for chucking the disk
The machining accuracy of item 4 is poor.

(2) As shown in (b), when the angle ρ3 of each of the quadrangles a1 to as is steep, the hysteresis error is large and the torque of the stepping motor is insufficient.

(3) (c) As shown in d, rectangles al to a4
If the positions of a5 and a6 are far apart, the upper and lower assemblies of the magnetic head are defective.

As shown above, it can be determined at a glance.

According to this embodiment, (1) accuracy of position adjustment, (2) static angle error of stepping motor, hysteresis error, (3) chucking error of 1 ijlk disk, assembly error of upper and lower magnetic heads.

can be displayed all at once graphically on the screen, making it easier to visually understand the causes of off-track.In addition, as with magnetic disk drives, the accuracy of each component has reached its limit, and the required accuracy is mutually adjusted based on probability distribution. By verifying products that are designed with this in mind at the assembly level, the positioning errors of the head carriage drive unit can be identified for each magnetic disk drive.

If the tolerance is not met, which component is defective?

Alternatively, it can be determined whether the assembly is defective, which has the effect of improving productivity and reliability during reassembly.

〔Effect of the invention〕

According to the present invention, in a magnetic head positioning inspection of a magnetic disk drive device, the reference adjustment signal recorded on the alignment disk is 1. By reading with a magnetic head, the amount of off-track for each track corresponding to the excitation phase of the stepping motor of the drive device is measured, and the display device calculates the chucking error and hysteresis error due to the direction of carriage movement for each track in a polygon. Since it is expressed as the side length and shape, it is easier to visually understand the off-track factors, and the positioning error of the head carriage drive can be seen at a glance, greatly reducing LSM time, improving productivity and reliability. This has an excellent effect.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a magnetic disk drive device that verifies the amount of off-track, Figure 2 is a diagram of a data input device that measures and displays off-track, and Figure 3 is an example of an alignment disk used in the adjustment device shown in Figure 2. Figure 4 is a diagram showing the static angle error of the stepping motor, Figure 5 is a reproduction output diagram of the adjustment signal of the alignment disk in Figure 2, and Figure 6 is a diagram showing the calculated off-track amount on the screen of the display device. FIG. 7 is a diagram showing a display example when the off-track is not within the tolerance value, FIG. 8 is a diagram showing a conventional example of an alignment disk, and FIG. 9 is a diagram showing a conventional example of an alignment disk. FIG. 3 is a diagram illustrating an example of a tracking adjustment device. DESCRIPTION OF SYMBOLS 1... Alignment disk, 2... Magnetic disk drive device, 7... Display device, 11-14... W4 alignment track center, 16-18... Track diameter adjustment signal,
25...Stepping motor, 28...Carriage, 29...Magnetic head.

Claims (1)

[Claims] 1. A chucking device for grasping a magnetic recording medium, a magnetic head for recording or reproducing data on the magnetic recording medium, a carriage for mounting the magnetic head, and a chucking device for holding the magnetic recording medium. In a tracking error display method when inspecting a magnetic disk drive device having a drive section that moves in a radial direction of a track on a medium, a number of concentric reference adjustment signals corresponding to excitation phases of a stepping motor of the drive section is provided. The track diameter can be determined by reading out each reference adjustment signal over one revolution with the magnetic head using an alignment disk having recorded the reference adjustment signal and a display device that calculates and displays the reference adjustment signal input to the magnetic head. An off-track amount, which is the amount of deviation of the magnetic head with respect to a predetermined position in the direction, is measured, and from the off-track amount, a chucking error of the chucking device for each moving direction of the carriage and a hysteresis error depending on the moving direction of the carriage are calculated. A tracking error display method for a magnetic disk drive device, characterized in that each error is calculated and displayed by the side length and shape of a polygon for each track of the reference adjustment signal. 2. The polygons corresponding to the excitation phases of the stepping motor are represented as rectangles, and the rectangles are collectively displayed at positions corresponding to the off-track amount on the display device, and the positional relationship of the rectangles is used to determine the distance between the excitation phases. 2. A tracking error display method for a magnetic disk drive device according to claim 1, wherein variation in positioning error is displayed. 3. Measure the off-track amount of the upper head and lower head of the magnetic head, simultaneously display the polygons representing the error amounts of the upper head and the lower head on the display device, and display the polygons. 3. A tracking error display method for a magnetic disk drive device according to claim 1, wherein the error between the upper and lower heads is displayed based on a positional relationship. 4. The chucking error for each direction of carriage movement is represented by the length of two lines parallel to the position corresponding to the off-track amount, and the hysteresis error is expressed by connecting the ends of the two lines. A tracking error display method for a magnetic disk drive device according to any one of claims 1 to 3, characterized in that the tracking error is represented by an ellipsoid.