JPH036438A - Evaluating method of durability of disk medium - Google Patents

Abstract

PURPOSE:To obtain the same result of evaluation as in the case when a damage occurs in an actual apparatus, by bringing the edge of a head into contact with the surface of a disk medium with an angle of inclination of the head changed and by damaging a recording layer of the disk medium by the edge of the head. CONSTITUTION:A disk medium 1 is rotated by a driving means 2 and the drive is stopped when a prescribed speed of rotation is reached. When the rotation of the medium 1 is stopped, the drive is started again. The means 2 repeates this operation and the number of times of the repeated operations is recorded. By moving a press contact means 6 in the direction of an arrow C-D, a head 3 can be brought into contact with the medium 1 with an angle of inclination of the head changed. By turning a spring 4 in the direction of an arrow A, in addition, the head 3 can be brought into pressure contact with the medium 1 with a set pressure. As the edge of the head 3 scrapes the surface of the medium 1 and gets deep into it, vibration becomes large and this vibration is transmitted to a converting means 5 through the spring 4. The means 5 converts an elastic wave consequent upon the vibration into an electric signal and delivers it to a comparing means 7. When a peak value of the signal exceeds a threshold value, the means 7 sends out the signal to a terminal E.

Description

[Detailed Description of the Invention] [Summary] This method relates to a durability evaluation method for disk media that evaluates the degree to which the edge of a head can withstand damage caused by contact with a rotating disk medium. The purpose of this method is to tilt the head at a specified angle and rotate the edge of the head in order to obtain the same evaluation results as those generated in disk devices and to make it easier to perform evaluation tests. a compression means for pressing the head against the surface of the disk medium with a preset pressure; a conversion means for converting elastic waves caused by vibrations generated when the head rubs against the rotating disk medium into an electrical signal;
a driving means for rotating the disk medium, and when the disk medium is rotated from a stopped state and reaches a predetermined rotational speed, the drive to the disk medium is stopped and the disk medium is brought to a stopped state; Repeat the driving operation of rotating again and stopping the drive when a predetermined rotational speed is reached, and calculate the number of times the driving operation is repeated until the peak value of the electrical signal converted by the converting means becomes equal to or higher than a predetermined threshold. The durability of the disk medium is evaluated by measuring each specified inclination angle of the head.

[Industrial application field]

The present invention relates to a disk medium used in a disk device, and in particular, a method for evaluating the durability of a disk medium to evaluate the extent to which it can withstand damage caused by the edge of a head coming into contact with a rotating disk medium. Regarding.

In recent years, with the demand for higher recording density in magnetic disk devices,
As the rotational speed of the disk medium increases, the flying height of the head decreases. Along with the demand for shortening access time, the moving speed of the head when performing a seek to position the head on a target track is increasing.

As a result, the acceleration and deceleration when the head moves becomes severe, the head vibrates, and the edge of the head often contacts the surface of the disk medium, causing the edge of the head to touch the surface of the disk medium. Damage may occur. When the edges of the heads come into contact in this way, the smaller the flying height of the head, the faster the rotating speed of the disk medium, and the faster the moving speed of the head, the greater the damage to the disk medium. There is a need to further improve gender than it currently is.

To this end, it is important to establish a method for evaluating the durability of disk media when the edges of the heads come into contact.

[Conventional technology]

Conventionally, as a method for evaluating the durability of a disk medium, an alumina slider or a thin film slider of a head used in a magnetic disk drive is pressed onto the surface of the disk medium, the disk medium is rotated at a predetermined speed, and the slider is rotated at a predetermined speed. There is a high-speed sliding method that measures and evaluates the time until the surface of the disk medium is damaged by rubbing the surface of the disk medium against the surface of the disk medium.

Also, by tilting the lead of a pencil at a predetermined angle and pressing it against the surface of the disk medium, and rotating the disk medium at a predetermined speed, the pencil lead and the disk medium are rubbed against each other, thereby causing damage to the disk medium. There is a pencil hardness stylus method that measures and evaluates the depth of scratches.

[Problem to be solved by the invention]

The high-speed sliding method involves sliding by contact between the surfaces of the slider and the disk medium, and the conditions are different from those in which the edges of the head, that is, the edges of the slider, contact.
There is a problem that accurate durability evaluation cannot be performed.

In addition, although the pencil hardness stylus method has similar conditions to the case where the edge of the head makes contact, it requires skill in processing pencil lead, etc., and does not necessarily involve contact between the edge of the head and the disk medium, which occurs in actual magnetic disk devices. There is a problem in that the same evaluation will not necessarily be obtained in the case of contact and damage.

In view of these problems, it is an object of the present invention to provide a durability evaluation method that can obtain the same evaluation results as those generated in an actual magnetic disk device and that can easily perform evaluation tests. The purpose is

[Means to solve the problem]

FIG. 1 is a diagram illustrating the present invention in detail.

The disk medium 1 starts rotating by being driven by the driving means 2, and when a predetermined rotational speed is reached, the driving means 2 stops driving the disk medium 1, so that the rotational speed gradually decreases and eventually stops. When the rotation of the disk medium 1 stops, the driving means 2 drives the disk medium 1 so that the disk medium 1 starts rotating again and reaches a predetermined rotation speed.

Here, since the driving means 2 again stops driving the disk medium 1, the rotation speed of the disk medium 1 sequentially decreases and stops. The driving means 2 repeatedly executes the operations described in ``2''.

In order to press the head 3 attached to the end of the spring 4 onto the surface of the disk medium 1 with a preset pressure, the pressure bonding means 6 rotates the spring 4 with a rotational force set in the direction of arrow A, and also presses the head 3 attached to the tip of the spring 4 with a preset rotational force. Move in the direction of arrow C or D to tilt at the specified tilt angle.

Since the head 3 is pressed against the surface of the disk medium 1, the vibration becomes more intense as the rotational speed of the disk medium 1 increases. This vibration is transmitted through the spring 4 to the converting means 5.
The converting means 5 converts the elastic wave accompanying the vibration of the spring 4 into an electrical signal, and sends it to the comparing means 7.

The comparison means 7 compares the peak value of the electrical signal sent by the conversion means 5 with a threshold value, and sends a signal across the terminal when the threshold value is exceeded. The peak value of this electrical signal increases as the damage to the recording layer of the disk medium 1 increases, so by comparing it with a certain threshold value, it is possible to always accurately detect the damage state.

Therefore, by checking how many times the drive means 2 has driven the disk medium 1 before sending out this signal, and measuring this number of times at each designated tilt angle of the head 3, the durability of the disk medium 1 can be accurately determined. It can be evaluated.

[Effect]

With the above configuration, the pressure bonding means 6 moves in the direction of the arrow C-D, and the spring 4 can be brought into contact with the disk medium 1 at a different angle of inclination in the direction of the arrow A. It is possible to reproduce the same contact state as the head 3 in a magnetic disk device.

Then, the edge of the head 3 scrapes the surface of the disk medium 1,
The deeper the penetration, the larger the vibration becomes, and when the peak value of the electrical signal corresponding to the magnitude of the vibration exceeds a predetermined threshold, a certain damaged state of the disk medium 1 can be detected.

Therefore, the same evaluation results as those generated in an actual magnetic disk device can be obtained, and evaluation tests can be easily carried out.

〔Example〕

FIG. 2 is a block diagram illustrating an embodiment of the present invention, and FIG. 3 is a diagram illustrating the operation of FIG. 2.

A surface plate 8 with extremely small runout (surface vibration) when rotated is attached to a motor 9, and a disk medium 1 is fixed to this surface plate 8. Therefore, when the disk medium 1 rotates, the surface does not swing downward, and the head 3 is pressed against the surface of the disk medium 1 with stable pressure.

The drive circuit 14 supplies current to the motor 9 to rotate it, monitors the rotational speed of the motor 9 detected by, for example, a Hall element, and cuts off the current supplied to the motor 9 when the motor 9 reaches a predetermined rotational speed. do.

Then, when the motor 9 stops, current is supplied to the motor 9 again to rotate it, and when a predetermined rotational speed is reached, the current supplied to the motor 9 is cut off. The drive circuit 14 repeats this operation, and the counter 16 records the number of times this repeated operation is performed.

The slider of the head 3 is fixedly attached to the disk 11 by a spring 4, and when the disk 11 rotates in the direction of arrow A, it is pressed against the surface of the disk medium 1 by the pressure horn transmitted through the spring 4. .

The disk 11 is given a rotational force by the motor 13, and the rotation of the disk 11 stops when the driving force sent out by the motor 13 and the repulsive force of the spring 4 are balanced. The drive circuit 14 then supplies the motor 13 with a current that generates the driving force desired by the operator.

Therefore, the operator measures the pressing force of the head 3 against the disk medium 1 using the strain gauge 17, and applies the desired driving force to the motor 13 by, for example, operating a variable resistor provided in the drive circuit 14. The generated current is sent out.

For example, the strain gauge 17 measures the resistance value between the head 3 and the disk medium 1 and displays this as a pressure force.

Further, the disk 11 and the motor 13 are attached to the support column 12, and this attachment can be moved in the direction of arrow C-D by adjusting the mechanism. A tilt angle is determined.

FIG. 3(a) shows the inclination angle of the head 3. As the disk 11 moves in the direction of arrow C, the inclination angle θ of the head 3 increases, as shown in ■ in FIG. 3(a). , the more you move in the direction of the arrow, the more θ3. As shown by θ4 in (2), the inclination angle gradually decreases.

Spring 4 has AE (Acoustic Emissi)
on) element 10 is attached, for example, JP-A-61
When the head 3 rubs against the disk medium 1 and vibrates using a known circuit as shown in Japanese Patent No. 227220,
This vibration is transmitted to the AE element 10 via the spring 4, and an output having a waveform as shown in FIG. 3(b) is sent to the comparator circuit 15 in accordance with the rotational speed of the disk medium 1.

That is, when the disk medium 1 starts rotating and the rotational speed increases, an output waveform whose level increases in proportion to the rotational speed is sent from the AE element 10 to the comparison circuit 15, as shown in (■) in FIG. 3(b). The current peaks when the disk medium 1 reaches a predetermined rotational speed, and when the current supplied to the motor 9 is cut off, the level gradually decreases as the rotational speed of the disk medium 1 decreases. do.

The rotation of the disk medium 1 is stopped, and the motor 9 is turned on again.
When a current is supplied to the disk medium 1 and the disk medium 1 starts rotating again, an output waveform as shown in (2) in FIG. 3(b) is obtained in the same manner as described above.

As damage occurs to the surface of the disk medium 1 and the vibration of the head 3 becomes more intense, A
When the level of the waveform sent from the E element 10 increases and its peak value exceeds a threshold value as shown in (2), the comparator circuit 15 sends a signal to the terminal E.

Therefore, the value on the counter 16 when the comparison circuit 15 sends a signal to the terminal E indicates the durability of the disk medium 1.

In this embodiment, the output waveform of the AE element 10 was monitored by the comparator circuit 15, but it goes without saying that an oscilloscope or the like may also be used.

〔Effect of the invention〕

As explained above, the present invention uses a head used in a magnetic disk drive, and brings the edge of the head into contact with the surface of the disk medium by changing the angle of inclination, thereby preventing damage to the recording layer of the disk medium by the edge of the head. This makes it possible to perform a wide range of evaluations, obtain the same evaluation results as those generated in an actual magnetic disk drive, and also provide an AE system that sends out an output waveform with a peak value corresponding to the damage state of the recording layer.
Since a certain damage state is always detected by the element, there is an effect that accurate evaluation can be performed and evaluation tests can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the present invention in detail, FIG. 2 is a block diagram explaining one embodiment of the present invention, and FIG.
The figure is a diagram explaining the operation of FIG. 2. In the figure, 1 is a disk medium, 2 is a drive means, 3 is a head, 4 is a spring, 5 is a conversion means, 6 is a compression means, 7 is a comparison means,
8 is a surface plate, 9.13 is a motor, 10 is an AE element, 11 is a disc, 12 is a column, 14 is a drive circuit,
15 is a comparison circuit, 16 is a counter, and 17 is a strain gauge. 3 4 Diagram showing the six dramas in Figure 2

Claims (1)

[Claims] Pressing means (6) for tilting the head (3) at a specified angle and pressing the edge of the head (3) against the surface of the rotating disk medium (1) with a preset pressure. ), a conversion means (5) for converting into an electrical signal an elastic wave accompanying vibration generated when the head (3) rubs against the rotating disk medium (1), a drive means (2) for rotating the disk medium (1) from a stopped state and when a predetermined rotational speed is reached, stopping driving the disk medium (1) and rotating the disk medium (1); ) is in a stopped state, repeats the driving operation of rotating again and stopping the drive when a predetermined rotational speed is reached, and the peak value of the electric signal converted by the converting means (5) becomes equal to or higher than a predetermined threshold. The number of repetitions of the drive operation up to the head (3)
A method for evaluating the durability of a disk medium, characterized in that the durability of the disk medium (1) is evaluated by measuring at each specified inclination angle.