JPH05314401A - Apparatus and method for testing magnetic recording medium - Google Patents

Abstract

PURPOSE:To simultaneously, efficiently evaluate absorption characteristics, a frictional force, a protective film, a floating state, etc., of a magnetic recording medium in a short time by composing a testing apparatus of a magnetic head, a high frequency sensor, a driving mechanism and an output conversion display unit. CONSTITUTION:A magnetic head is fixed to a predetermined position on a magnetic disk of a state in which a stop and a high speed rotation are repeated, the head is vibrated by a sliding contact generated between the disk and the head, and an amplitude of the vibration is displayed as an electric output by a strain gauge on an oscilloscope. Characteristic values of a magnetic recording medium is evaluated by a predetermined method based on a positional relation, a shape and an amplitude of an output signal waveform of the gauge of a cycle having four stages of a rotation starting stage 1, a rotation decelerating state 2, a stopping stage 3 and a normal rotation of the disk with respect to a reference line. Thus, many evaluations of the absorption force, the frictional force, etc., can be conducted in a short time, an efficiency of manufacture can be enhanced, and a quality of a product is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk used in a magnetic recording / reproducing apparatus, the magnitude of the attractive force and the frictional force generated between the magnetic disk and the magnetic head, the state of the magnetic disk surface, and the magnetic disk surface protective film. The present invention relates to a test apparatus and a test method for evaluating the characteristics and state or the flying state of a magnetic head on the surface of a magnetic disk very efficiently.

[0002]

2. Description of the Related Art The current general magnetic disk evaluation test method begins with the evaluation of the magnetic head used at this time.
The magnetic head is evaluated visually and the head used for the magnetic recording medium test is determined by examining the flying height and the flying posture with a head flying height measuring device. This requires 2 days and 3 measurers. Next, the quality characteristics of the magnetic disk are measured and evaluated. This is a Cont that repeatedly plays the stopped state and the high rotation state.
act StartStop Tester (hereinafter CS
The magnetic disk is fixed to the spindle of the S tester), the magnetic head is fixed at a predetermined position on the surface of the magnetic disk, and the magnetic disk is repeatedly rotated and stopped at a predetermined rotation speed by the spindle. ， The force acting on the magnetic head is continuously output and displayed as the electric signal of the load cell that detects the resistance change of the strain gauge, and it is generated between the magnetic head and the magnetic head of the magnetic disk based on the output characteristics when the rotation speed reaches a predetermined low speed. Determine the adsorption force, frictional force, and friction coefficient.

The above method is repeated for several days to several weeks to evaluate the durability of the magnetic disk. Furthermore, in order to evaluate the characteristics and condition of the protective film on the surface of the magnetic disk, and the floating state of the magnetic head in contact with the surface of the magnetic disk, a separate measuring device is used for the measurement, that is, hardness measurement by a hardness meter. 1 for hardness measurement by scratch tester
One day for roughness measurement with a roughness meter, two days for lubricant film thickness measurement and adsorption test, and two days for magnetic disk surface inspection with a scanning tunneling microscope. Considering this, it is necessary to have a total of 7 days, and one person is required for each evaluation test, for a total of 7 persons. Therefore, all evaluation tests require at least 9 days and 10 inspectors.

[0004]

In the prior art described above, a great deal of time and labor are required in the product evaluation of the magnetic disk, and the situation of the product being manufactured at the manufacturing site cannot be immediately notified. Depending on the product, there is a problem that it leads to frequent occurrence of defective products. In view of the above-mentioned problems in the prior art, an object of the present invention is to simultaneously, in a short time, with a small number of unskilled persons, efficiently and efficiently, the adsorption characteristics of the magnetic recording medium, the frictional force, the characteristics and state of the protective film, and the magnetic disk surface. It is an object of the present invention to provide a test apparatus and a test method capable of evaluating the flying state of a magnetic head in contact with a magnetic head.

[0005]

Means for Solving the Problems The inventors of the present invention have earnestly studied to solve the above problems, and have completed the present invention.
That is, the gist of the present invention is: (1) A magnetic recording medium testing device which is substantially composed of a magnetic head, a magnetic head mounting portion, a high frequency sensor, a drive mechanism, and an output conversion display device that can be measured quickly and easily. (2) Displaying an output characteristic curve of a cycle consisting of four stages of rotation deceleration, stop, rotation start and normal rotation of the magnetic recording medium using the magnetic recording medium test apparatus according to claim 1 or when the cycle is repeated Then, the magnetic recording medium test method is characterized in that the output characteristic curve is used to judge whether or not the characteristic values of the magnetic recording medium are met, or to select the magnetic head to be used and to evaluate the magnetic head mounting method.

The present invention will be described in detail below. The magnetic recording medium test apparatus used in the present invention has a magnetic head, an arm to which the magnetic head is attached at its tip, a plate with a sensor unit attached to the base of the arm, and a function of rotating or stopping by mounting a magnetic disk. It consists of a support (spindle), a device that converts and amplifies the electrical signal of the sensor, and an electrical signal display device (oscilloscope). A magnetic head dedicated to high-density magnetic recording is used. The spindle supports or rotates the magnetic disk in a stopped state, and the spindle motor is a main component. Spindle speed is 50
It is in the range of 0 to 6000 rpm, and one that can be set in units of 1 rpm is preferable. Further, it is necessary that the spindle can be set in the range of 4 to 30 seconds in units of 1 second in order to set the cycle number of a cycle consisting of four stages of rotation deceleration, stop, rotation start and normal rotation of the magnetic recording medium.

The magnetic head portion and the plate with the sensor portion can be linearly moved by a micro gauge in the radial direction, and the magnetic head can be moved to a predetermined position on the magnetic disk surface. The sensor has a resonance frequency of 2kHz or more and a response frequency of 0.
A high frequency sensor of ~ 1kHz is enough. Vibration (elastic wave) of the magnetic head caused by sliding contact between the magnetic disk and the magnetic head by rotating the spindle is converted into an electric signal by the strain gauge. The magnetic head is designed so that a preset pressure can be input by a computer and the test can be performed while applying the pressure.
Normally, the oscilloscope is set so that the strain gauge output is 4 V for a force of 10 gf applied to the head. The oscilloscope may be a commercially available storage type.

Next, the test method of the present invention will be described with reference to FIGS.
Will be described. Using a magnetic recording medium testing device, the magnetic head was fixed at a predetermined position on the surface of the magnetic disk that was repeatedly stopped and rotated at high speed, and the magnetic head was vibrated by the sliding contact between the magnetic disk and the magnetic head. The magnitude of vibration of the magnetic head by a high frequency sensor having a resonance frequency of 2 kHz or more and a response frequency of 0 to 1 kHz was taken out as an electrical output signal, and this electrical signal was displayed on an oscilloscope. FIG. 1 shows the basic output signal waveform. f ₁ represents the static friction force, ₁ in the CSS test of the magnetic disk represents the rotation start stage, 2 represents the rotation deceleration stage,
This waveform is important for knowing the flight posture of the head, the surface condition of the magnetic disk, the amount of lubricant, and the condition of the protective film.

Reference numeral 3 shows the state of the magnetic head when the magnetic disk is stopped. If the strain gauge output of this waveform is positive, adsorption does not occur between the magnetic disk and the magnetic head, and the lubricant and the magnetic head are not present. Is in a good balance state, and if this is a negative value, the value of f ₁ becomes large, indicating that the magnetic head is adsorbed on the magnetic disk, and the balance between the lubricant and the magnetic head is poor. .. This phenomenon occurs because a slight reverse rotation is applied when the spindle rotation stops, and if the magnetic head is attracted to the magnetic disk, the magnetic head is pulled in the opposite direction, and the strain gauge output also becomes a negative display. Reference numeral 4 represents impulse, which represents the amount of load applied to the magnetic disk by the magnetic head.

As described above, by analyzing the signal waveform of FIG. 1, it is possible to know the state between the magnetic disk and the magnetic head, the magnitude of the attraction force / friction force, and the like. FIG. 3 shows a repeated test of a cycle in which a magnetic head is fixed at a predetermined position on the surface of a magnetic disk, for example, a CSS zone, a rotation start step 15 seconds, a rotation deceleration step 15 seconds, a stop 1 second, and a high speed rotation (6000 rpm) 1 second. A CSS test) is performed and used as a criterion for judging whether the conditions such as the protective film on the magnetic disk surface and the lubricant are good. When the magnetic disk and the magnetic head are positioned by the magnetic recording medium testing device, the output signal changes due to the difference in the vibration as shown in Fig. 3 depending on the amount of lubricant with a certain roughness of the magnetic disk surface. To do. Also in this case, when positioning the magnetic head on the magnetic disk surface, a position having a statistically large difference in attraction force is determined in advance, and the magnetic head is positioned at that position by a micro gauge. In the magnetic disk which it has, it is set to the CSS zone position.

FIG. 3 shows the relationship between the output signals of the lubricant and strain gauge and the attraction force / friction force according to the above-mentioned method. The output of the strain gauge of the sensor unit gradually increases as the amount of lubricant increases. This is because output force at stop is increased as shown in Fig. 3 (c) due to an increase in attracting force of both the magnetic head and the magnetic disk and an increase in viscous resistance force due to the surface tension of the attracting force and the friction force as the lubricant material increases. The waveform becomes lower than the reference line (0 coordinate line), and the shape of the output characteristic waveform during rotation deceleration and rotation start becomes rough and the amplitude becomes large. Further, as shown in FIG. 3A, when the amount of lubricant is small, the magnetic head directly scratches the surface of the magnetic disk to cause a head crash phenomenon, and the shape of the output characteristic waveform in the rotation deceleration stage and the rotation start stage becomes rough and the amplitude becomes large. Become.

The minimum amount Lmin of the lubricant capable of preventing the head crash phenomenon and the amount of the lubricant capable of preventing the attraction phenomenon due to the increase of the attraction force and the friction force between the magnetic head and the magnetic disk. Lmax is appropriately selected, and the strain gauge output ranges Pmin to Pmax corresponding to these lubricants are used as reference levels. When the magnetic disk and the magnetic head are positioned by the magnetic recording medium testing device, the output signal is changed by the vibration as shown in FIG. 4 depending on the roughness amount with a certain amount of lubricant. ing. In this case, when positioning the magnetic head on the magnetic disk surface, a position having a large difference in attraction force is statistically obtained in advance and the magnetic head is positioned by the micro gauge at that position.
For example, it is positioned at the CSS zone position.

FIG. 4 shows the relationship between the magnitude of the roughness of the magnetic disk surface, the output signal of the strain gauge, and the attraction force with the amount of lubricant kept constant. In the figure, as the surface roughness of the output of the strain gauge of the sensor unit becomes smaller than the target value, the shape of the characteristic waveform at the time of rotation deceleration and rotation start becomes rough and the amplitude also becomes large. This is because when the roughness of the magnetic disk surface increases, the contact area between the magnetic disk surface and the magnetic head decreases, and the attraction of both the magnetic head and the magnetic disk due to the surface tension of the lubricant reduces the rotation of the spindle. The flying / grounding of the magnetic head on the magnetic disk due to repeated stoppage becomes close to the reference waveform shown in FIG.

A predetermined position on the surface of the magnetic disk, for example, CS, where the surface roughness and the amount of lubricant are made constant by a magnetic recording medium testing device.
With the magnetic head fixed in the S zone, a cycle of 15 seconds for rotation start, 15 seconds for rotation deceleration, 1 second for stop, and 1 second for high-speed rotation (6000 rpm) was repeatedly tested, and the magnetic head on the magnetic disk surface tilted during normal rotation. When the protective film is floating or has an abnormal shape or is thin in thickness, a characteristic waveform having a waviness as shown in FIG. 6 is obtained. The magnetic head is fixed to a predetermined position on the surface of the magnetic disk, for example, the CSS zone, where the surface roughness and the amount of lubricant are kept constant by the magnetic recording medium testing device,
Rotation start 15 seconds, rotation deceleration 15 seconds, stop 1 second, high speed rotation (6000 rpm) 1 second cycle repeated test,
FIG. 6 shows that the flying posture of the magnetic head on the surface of the magnetic disk causes catering, and it is evaluated that the magnetic disk is good but the magnetic head is defective. Further, FIG. 7 shows that the magnetic head is not flying above the surface of the magnetic disk during normal rotation when the same method as described above is performed, and shows that the magnetic head is defective. In this way, the flying state of the magnetic head on the magnetic disk surface can be easily known, and a good magnetic head for inspecting the magnetic recording medium can be selected by this method.

[0015]

EXAMPLES The contents of the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Using the same 5.25-inch magnetic disk and the same magnetic head, the magnetic disk characteristic values were evaluated according to the method of the present invention and the conventional method. In the method of the present invention, a 5.25-inch magnetic disk prepared for magnetic head inspection was attached to a spindle of a magnetic recording medium testing device, and then a magnetic head (Al203.Ti) was attached to a magnetic head arm.
After mounting the C slider head), rotation deceleration, stop,
The cycle of rotation start and normal rotation is repeated, the flight state and attitude are inspected, and the test magnetic head is selected. Next, attach the magnetic head to the magnetic recording medium testing device,
Attach a 5.25-inch magnetic disk to the spindle,
The magnetic head is vibrated by the sliding contact that occurs between the magnetic disk and the magnetic head, and the magnitude of the vibration of the magnetic head by the high frequency sensor with a resonance frequency of 2 kHz or more and a response frequency of 0 to 1 kHz is extracted as an electrical output signal. Was displayed on an oscilloscope and the pass / fail of the magnetic disk characteristic values was evaluated. The time required for the test in the method of the present invention was 40 minutes, and the number of required personnel was one.

In the conventional method, the magnetic head for inspection (Al
203 ・ TiC slider head). First, the magnetic head is visually selected to check for scratches and the like by using a stereoscopic microscope, the flight attitude and flight state are inspected with a groove-butt flying space analyzer, and the passed one is used for the CSS test. For magnetic disk surface roughness measurement, the inner, middle, and outer surface roughness is measured with the Dektak IIA, and it is inspected whether it is within ± 5% of the target value. The surface hardness of the magnetic disk is measured with a NEC MHA-400 type thin film hardness meter and a Shimadzu SST-101 scratch hardness meter. The surface condition of the magnetic disk is Seiko Electronics STA-350.
Scan with a scanning tunneling microscope and X-ray inspection system. The thickness and amount of the lubricant are inspected by Fuji Electric FTIR to determine whether they are the target values or the appropriate values. For the CSS test, a KT202 type CSS tester manufactured by Onoda Cement was used, and the CSS test was performed using the magnetic head selected by the above method.
000 cycles to test the durability of the magnetic disk.
The time required for the test in the conventional method was 9 days, and the number of required personnel was 10.

[0017]

As described above, according to the present invention, the attraction / frictional force between the magnetic disk and the magnetic head, the degree of lubricity, and the surface of the magnetic disk are utilized by using the rotation / stop repeated magnetic disk durability test apparatus. Condition and amount of surface coating agent,
Unlike many conventional inspection and evaluation devices that take a long time to evaluate the state of the protective film and the flying state of the head, all of these can be evaluated in a short time only with this device, and The state of the product flowing in the line, troubleshooting, and quality control can be performed, the efficiency of manufacturing can be improved, the product quality can be improved, the number of defective products can be reduced, and the mass production of defective products can be prevented. Since the evaluation time is 40 minutes, it is possible to effectively utilize human resources and save labor.

[Brief description of drawings]

FIG. 1 is a basic output characteristic waveform displaying a piezoelectric element output during a CSS test of a magnetic disk.

FIG. 2 is a characteristic waveform that serves as a reference and is a characteristic waveform during a CSS test of a magnetic disk having a well-balanced amount and roughness of a lubricant and a protective film.

FIG. 3 is a characteristic waveform showing changes in the amount of lubricant and the suction force in a CSS test.

FIG. 4 is a characteristic waveform showing changes in adsorption force and friction force depending on the surface roughness of a magnetic disk in a CSS test.

FIG. 5 is a characteristic waveform showing a change in the thickness of a defective product or a protective film in which the flying posture of the magnetic head is bad in the CSS test.

FIG. 6 is a characteristic waveform when a flying state of a magnetic head on a magnetic disk surface in a CSS test is a catering state.

FIG. 7 is a characteristic waveform in a state where the magnetic head is not levitated on the magnetic disk surface in the CSS test.

[Explanation of symbols]

1 Output waveform of rotation deceleration stage 2 Output waveform of rotation start stage 3 Output waveform of stop state 4 Impulse (load applied to magnetic disk by magnetic head) f ₁ Static friction force

Claims (3)

[Claims] 1. A magnetic head capable of quick and easy measurement,
A magnetic recording medium testing device substantially composed of a magnetic head mounting portion, a high frequency sensor, a driving mechanism, and an output conversion display device. 2. An output characteristic curve of the magnetic recording medium test apparatus according to claim 1 in a cycle consisting of four stages of rotation deceleration, stop, rotation start and normal rotation of the magnetic recording medium or when the cycle is repeated. Is displayed, and the pass / fail of the magnetic recording medium characteristic value is evaluated by the positional relationship of the characteristic curve at the time of stop to the reference line or the shape or amplitude of the output characteristic curve at the rotational deceleration stage or the rotational start stage. Magnetic recording medium test method. 3. An output characteristic curve of the magnetic recording medium test apparatus according to claim 1 in a cycle consisting of four stages of rotation deceleration, stop, rotation start and normal rotation of the magnetic recording medium or when the cycle is repeated. Is displayed, and the quality of the magnetic head or the method of mounting the magnetic head is evaluated by the shape or amplitude of the output characteristic curve at the rotation deceleration stage or the rotation start stage.