JPH02287205A - Instrument for inspecting nature and state of magnetic disk surface - Google Patents

Abstract

PURPOSE:To enable a surface defect position to be easily specified by detecting an abnormal value and a deviation value by comparing an irregular reflection state value stored this time with a surface state value stored at the previous time and providing an instrument with comparative arithmetic means for displaying the position. CONSTITUTION:Laser light incident on a measuring position surface on a truck, a magnetic head slider on a magnetic disk being brought into contact with the surface, is irregularly reflected in accordance with a surface roughness and the reflected laser light is incident on a plurality of photodetectors 11. A signal in accordance with the degree of detected light is stored in a storage device 14 as an up-to-date measured value via an amplifier 12 and an A/D converter 13. At the same time, a positional signals from a slider drive controller 4 and a rotational angle detector 9 are also stored in the controller 4. Measured data in the controller 4 are compared with a state value stored at the previous time and a required value separately set in a comparative arithmetic unit 15, detected as an abnormal value or a deviation value and outputted to a display unit 16 with the stored positional signal of measuring positions.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to an apparatus for continuously monitoring and inspecting the surface quality of a magnetic disk. By using a light-receiving element to understand and store the changes in the disk surface, partial defects on the disk surface can be detected by comparing relative or absolute values, and inspections can be made while the magnetic head is in contact during durability tests, etc. The present invention relates to a magnetic disk surface quality inspection device.

Background technology Magnetic disks are widely used as external storage devices in today's highly developed computers, and to meet the demands for smaller size, larger capacity, and faster speeds, thin-film magnetic heads were developed, making it essential to fly at minute intervals. Therefore, there is a demand for further improvement in the performance of magnetic disks, that is, improvement in defect-free film formation on the disk surface and improvement in wear resistance.

Inspection of magnetic disks includes - In addition to inspection and measurement of magnetic properties by boat, abrasion tests such as sliding tests and C85 (Cont.
act 5 tart 5 top) tests, optical microscopes and electron micrographs are used to inspect the surface properties of magnetic disks, and EPMA, etc. are used to inspect deposits on magnetic heads after CSS tests. was analyzed.

For example, to inspect changes in the surface of magnetic disks and magnetic heads after a CSS test, the above-mentioned electron micrograph, E
PMA analysis is used to investigate deposits, but the analysis requires a large amount of time and process, and it is difficult to identify defective areas on the magnetic disk surface. There was a problem in that it was only possible to understand the state after the change, and it was not possible to continuously capture changes over time.

Therefore, during the CSS test, the sliding noise between the magnetic head and the disk was measured using AE (Acoustic Emission).
On) Attempts have also been made to detect changes in the surface properties of magnetic disks using sensors.

The combined use of an AE sensor is suitable for understanding the differences between the magnetic head material and magnetic disk surface film material in CSS tests, as well as changes in sliding conditions due to the number of tests.
It is unsuitable for continuously monitoring changes over time or for understanding changes in the state of defective areas on the surface of a magnetic disk.

It is generally known that the sliding state between the magnetic disk and the slider surface does not necessarily match the state change of surface defects, and in particular, with conventional inspection methods and equipment, surface texture inspection and CSS test etc. are performed at the same time. Therefore, it is difficult to make a comprehensive judgment during inspection, making it difficult to grasp changes in the defect state on the surface of the magnetic disk, and furthermore, there is a problem in that defective locations cannot be displayed in real time during inspection.

Purpose of the Invention The present invention provides a method for inspecting the surface properties of magnetic disks.
When the magnetic head is in contact with the SS test, etc., surface texture inspection can be performed at the same time. For example, the wear test results, friction force measurement results, and surface texture of a specified location on the required track on the magnetic disk surface can be comprehensively examined at the same time. The object of the present invention is to provide a magnetic disk surface texture inspection device that can continuously evaluate the surface properties of magnetic disks and easily identify surface defect locations.

Summary of the Invention The present invention provides a magnetic disk rotation drive device equipped with a magnetic head slider, in which a laser beam is emitted at a predetermined angle of incidence onto the surface of the magnetic disk at a predetermined position on a track in contact with the magnetic head slider. a laser device that emits light, one or more light receiving elements disposed above the disk surface to sense the diffused reflection state of the laser light at the predetermined position, and a storage means for storing the diffused reflection state of the laser light at each position. , a position detecting means for specifying the position on the magnetic disk based on the track position in the radial direction of the magnetic disk and the rotation angle of the magnetic disk, and detects the currently stored diffuse reflection state value, the previously stored surface state value, and the previously stored surface state value. An apparatus for inspecting surface properties of magnetic disks, characterized in that it has a comparison calculation means for detecting abnormal values and deviation values by comparing them with an average value or a set value of surface condition values obtained multiple times, and displaying the position thereof. In addition, when the magnetic disk rotation drive device is a CSS test device, an AE sensor is attached to the magnetic head slider, and the noise value of the AE sensor and the laser beam during the CSS test at each position on the magnetic disk are measured. This is a surface texture inspection device for a magnetic disk, which is equipped with a comparison calculation means for detecting an abnormal value by comparing it with a diffuse reflection state value and displaying its position. In this case, the magnetic disk is equipped with a comparison calculation means for comparing the friction force value at each position on the magnetic disk and the diffuse reflection state value of the laser beam, detecting an abnormal value, and displaying the position. This is a surface texture inspection device.

Structure of the Invention The present invention is directed to a magnetic disk surface on a track in contact with a magnetic head slider at an incident angle of 5 to 30'.
When the measurement point on the track is irradiated at an angle of The light-receiving elements detect changes in the amount of reflected light incident on each light-receiving element, and from changes in the amount of reflected light, the rate of change in the surface roughness of the magnetic disk can be detected, or from rapid changes in the amount of reflected light, it is possible to detect thin film peeling. The gist of this is to detect partial defects such as cracks and dropouts.

Furthermore, the present invention is characterized in that the surface quality of the magnetic disk can be continuously monitored and inspected while the magnetic head is in contact with the magnetic disk. This is an inspection device that can comprehensively and relatively judge the surface quality of a magnetic disk by comparing it with the noise value of the AE sensor or the measured value of friction force.

In this invention, the laser device needs to be configured to be able to emit a laser beam at a predetermined angle of incidence onto the measurement position surface on the track of the magnetic disk surface that is in contact with the magnetic head slider. The irradiation part is tilted at a predetermined angle, and the laser device moves in synchronization with the magnetic head slider onto the disk sliding surface that contacts the other rail surface of the slider, and simultaneously irradiates onto the other sliding surface. Various configurations can be used, such as a configuration having a plurality of irradiation units and light receiving elements.

In this invention, the light-receiving element senses the state of diffuse reflection of the laser beam at the measurement position, and one or more light-receiving elements are arranged above the measurement position, and as the laser device moves, the measurement point of the desired track is adjusted. It is also a good idea to configure it so that it can be moved to.

The arrangement of the light-receiving elements must be such that the state of diffuse reflection of the laser light at the measurement position can be quantitatively captured as a change in the amount of reflected light incident on each light-receiving element. There is a need.

Further, in the present invention, the storage means for storing the diffused reflection state of the laser beam at each measurement position stores information on which element of the n light-receiving elements (Xi to Xn) arranged at required positions the laser beam is incident. In addition, this analog data may be converted into digital data to quantify and store the presence or absence of laser light incident on the n light receiving elements and its intensity, and may be stored and stored in the computer's internal memory or external storage device.

In addition, the position detection means at each measurement position can, for example, detect the track position in the radial direction that the magnetic head slider is currently in contact with, and divide one rotation of the magnetic disk in advance by a required angle, and calculate the known rotation angle. By detecting and counting the fixed angle with a detector, the position on the magnetic disk can be specified based on the track position and rotation angle, and this signal is stored in the storage means as a position signal of each measurement position when memorizing the diffuse reflection state of the laser beam. Make me remember.

The magnetic disk rotation angle detector described above is, for example, a CS
It can also be combined with a magnetic disk rotation drive control device, a magnetic head slider control device, etc. for the S test and incorporated into the same control system.

Furthermore, in the present invention, the comparison calculation means compares the currently stored diffuse reflection state value of one measurement position or the entire circumference of a certain track with the previously stored state value or a plurality of pre-computed values up to the previous time. It has a function to compare with the average value or set required value, detect it as an abnormal value or deviation value, and display it together with the stored position signal of each measurement position.

Based on the drawings (Disclosure of the invention) Figures 1a and 1b show a magnetic disk and a magnetic head slider.
FIG. 2 is an explanatory top view showing a laser device and a longitudinal cross-sectional view of a magnetic disk.

FIG. 2 is a block diagram showing a magnetic disk rotation drive control device.

FIG. 3 is a block diagram showing the light receiving element, storage means, and comparison calculation means of the present invention.

Here, an example of a magnetic disk surface quality inspection device will be described in which a laser device is combined with a magnetic disk rotation drive control device in which a CSS test device is provided with an AE sensor.

A magnetic disk (1) is clamped and rotationally driven by a disk drive device (2), and a magnetic head slider whose movement in the disk radial direction is controlled by a slider drive control device (4) is mounted on the surface of the magnetic disk (1). (3) are in contact.

Further, an AE sensor (5) is connected to the magnetic head slider (3), and detected noise between the slider and the disk is amplified by an amplifier (6) and input to the recording device (7).

The disk drive device (2) also includes a CSS control device (8) that controls rotational drive so that CSS tests can be performed.
is connected, and the rotation angle of the magnetic disk (1) is monitored by an attached rotation angle detector (9).

In the laser device (10), the laser irradiation part is tilted at a predetermined angle so that the laser beam is incident on the measurement position surface at a predetermined angle, and the entire device moves onto the same track in synchronization with the magnetic head slider (3). It is also a good idea to move it.

In order to sense the diffused reflection state of the laser beam at the measurement position, a support arm (not shown) from the laser device (10) is equipped with a
n light receiving elements (111 to 11n) are arranged at required positions.

As shown in FIGS. 1A and 1B, the laser beam irradiated at a predetermined incident angle onto the measurement position surface on the track that the magnetic head slider (3) on the magnetic disk (1) is in contact with, Diffuse reflection occurs depending on the surface roughness, and the reflected light enters a plurality of light receiving elements (111 to 11n).

In FIG. 3, a signal corresponding to the degree of light sensing by the light receiving elements (111 to 11n) is amplified by an amplifier (12), converted to a digital signal by a nine-way converter (13), and is converted into a digital signal by a storage device (14). ) as the latest measured value, and at the same time, the position signals from the slider drive control device (4) and rotation angle detector (9) are also stored.

This measurement is repeated to store the diffuse reflection state values around the entire circumference of the track.

The measurement data in the storage device (14) is stored in the comparison calculation device (1
In 5), as the latest memorized one measurement position or the diffused reflection state value for the entire circumference of a certain track, the last stored state value, or the average value of multiple diffused reflection state values calculated in advance up to the previous time, or It is compared with a separately set required value, detected as an abnormal value or deviation value, and outputted to the display device (16) together with the stored position signals of each measurement position.

In addition, the comparison calculation device (15) compares and contrasts the AE sensor data from the recording device (7) of the AE sensor (5) and the CSS test data input separately, and displays the position signal of the measurement position together with the display device (16). ).

Example material: Al2O3-TiC system, IBM3380 (product name)
In a magnetic disk rotating device equipped with a type of magnetic head slider, a material A1 that rotates at 125 rpm,
The slider was brought into contact with the surface of a magnetic disk of size 5) inch with a spring load of 9.5 g. At a predetermined measurement position on the track of the disk, an incident angle of 15°, He-Ne
A laser beam was emitted, and the diffused reflection state of the laser beam at the measurement position was received by one photocell placed directly above the surface of the magnetic disk at the measurement position, to determine the diffused reflection state.

The photocell signal corresponding to the degree of photosensitivity was stored as the latest measured value in a storage device via an amplifier and zero converter.

At the same time, a rotation angle detector that detects the position when one revolution of the magnetic disk is divided into 1024 parts at a division angle of 0.35° and a position signal from the slider drive control device were stored together.

The above measurement was repeated and the diffuse reflection state values around the entire circumference of the track were memorized.

The measurement data in the storage device is processed by a comparison calculation device as the latest stored one measurement position and the diffuse reflection state value for the entire track circumference, the previously stored state value, and the previously stored and calculated diffuse reflection. It was compared with the state average value, detected as an abnormal value or deviation value, and outputted to a display device together with the stored position signal of each measurement position.

As a result, during abrasion tests on predetermined locations on required tracks on the magnetic disk surface, the surface properties can be evaluated comprehensively and continuously at the same time, and local surface defects such as peeling or falling off of thin films can be identified after the abrasion test. was completed.

[Brief explanation of the drawing]

Figures 1a and 1b show the magnetic disk and magnetic head slider.
FIG. 2 is an explanatory top view showing a laser device and a longitudinal cross-sectional view of a magnetic disk. FIG. 2 is a block diagram showing a magnetic disk rotation drive control device. FIG. 3 is a block diagram showing the light receiving element, storage means, and comparison calculation means of the present invention. 1... Magnetic disk, 2... Disk drive device, 3
...Magnetic head slider-14...Slider drive control device, 5...AE sensor, 6...Amplifier, 7
...recording device, meter/CSS control device, 9...rotation angle detector, 10...laser device, 11...light receiving element, 12...amplifier, 13...9 converter, 14・
. . . Storage device, 15 . . . Comparison calculation device, 16 . . . Display device.

Claims (1)

[Claims] 1. In a magnetic disk rotation drive device equipped with a magnetic head slider, a laser beam is emitted at a predetermined angle of incidence onto the surface of the magnetic disk at a predetermined position on a track in contact with the magnetic head slider. a laser device for emitting light; one or more light-receiving elements disposed above the disk surface to sense the state of diffuse reflection of the laser light at the predetermined position; a storage means for storing the state of diffuse reflection of the laser light at each position; and a magnetic field. It is equipped with a position detection means for specifying the position on the magnetic disk based on the track position in the disk radial direction and the rotation angle, and the diffuse reflection state value stored this time is used as the surface state value stored last time, and the surface state value stored a plurality of times until the previous time. What is claimed is: 1. A surface texture inspection device for a magnetic disk, comprising a comparison calculation means for detecting an abnormal value or deviation value by comparing it with an average value or a set value of state values, and displaying the position thereof. 2. The magnetic disk rotation drive device consists of a CSS test device, and an AE sensor is attached to the magnetic head slider, and the noise value of the AE sensor during the CSS test at each position on the magnetic disk and the diffuse reflection state value of the laser beam are measured. 2. The magnetic disk surface texture inspection apparatus according to claim 1, further comprising comparison calculation means for comparing and detecting an abnormal value and displaying the position thereof. 3. The magnetic disk rotation drive device consists of a friction force measuring device,
A claim characterized in that a comparison calculation means is provided for comparing the friction force value at each position on the magnetic disk and the diffuse reflection state value of the laser beam, detecting an abnormal value, and displaying the position. 1. The magnetic disk surface quality inspection device according to 1.