JPH09231502A - Inspection method of magnetic disk medium - Google Patents

Abstract

(57) Abstract: It is possible to accurately detect the peak value of a spike-like waveform output from a detection means, and to accurately detect the position of contact not only in the track direction but also in the circumferential direction. It enables two-dimensional grasping of inspection results such as the specified contact state. SOLUTION: A vibration waveform having a specific frequency or more is extracted from a signal output from a detection unit that detects contact between a magnetic disk medium and a magnetic head, and track information and sector information obtained from the magnetic disk medium are extracted. Whether the seek state when the vibration waveform was extracted was the acceleration state or the deceleration state was determined from the access state information indicating the state of the magnetic head while specifying the position on the magnetic disk medium where the vibration waveform was extracted. Alternatively, it is specified whether or not it is in the on-track state.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to evaluation of the flying stability of a head of a magnetic disk device including a magnetic disk medium, a head, an actuator for driving the head, and a controller for these. The present invention relates to a method of inspecting a magnetic disk medium used for evaluating the surface condition of the magnetic disk medium, monitoring head crash, and the like. As for contact monitoring between a magnetic disk head and a magnetic disk medium (hereinafter abbreviated as “magnetic disk” or “medium”), many methods have conventionally been proposed for measuring the flying characteristics of the magnetic head. There are methods such as a method utilizing the interference of light and a method of knowing from the fluctuation of the output level from the head of the signal recorded on the magnetic disk. A method of using a piezoelectric element as a contact detection means for surface inspection of a medium is known, and an example of the medium inspection method will be described below with reference to FIG. FIG. 4 is a diagram showing an outline of a conventional magnetic disk medium inspection method. The magnetic head 2 floating above the magnetic disk 1 is connected via a gimbal 3 and a mounting arm 4 to an actuator 5, which is, for example, a cylinder, and the actuator 5 allows the magnetic head 2 to move in the radial direction of the magnetic disk 1. Be moved. A piezoelectric element 6 as a detecting means is mounted on the slider of the gimbal 3 or the magnetic head 2, and the detection signal is measured by an effective value voltmeter 7 or an oscilloscope 8. The medium inspection is performed by performing the same operation as when the apparatus is in operation. Now, when the magnetic disk 1 rotates, the magnetic head 2 floats. However, the magnetic disk 1 and the magnetic head 2 may come into contact with each other due to the surface condition of the magnetic disk 1 or the floating instability of the magnetic head 2. Then, the impact is detected by the piezoelectric element 6, the level is read by the RMS voltmeter 7, the level is plotted corresponding to the cylinder position, and which side of the cylinder position the level is high is evaluated. . Further, in the flying height measuring device for a magnetic head described in JP-A-55-64629, an oscilloscope 8 is connected instead of the effective value voltmeter 7. The horizontal axis on the screen of the oscilloscope 8 is a time axis, and the sweep is started every time the magnetic disk 1 reaches a certain rotation angle. When the magnetic disk 1 and the magnetic head 2 come into contact with each other, large-amplitude spike waveforms S1 and S2 are superimposed on a small-amplitude noise signal and displayed on the screen. The height of the spike waveforms S1 and S2 on the screen determines the degree of contact, and the surface condition of the magnetic disk can be inspected. As described above, the conventional method for inspecting the magnetic disk medium uses only the output information from the piezoelectric element 6 in the contact inspection between the medium and the head, and outputs the output. Since the track direction is evaluated from the level connected to the rms value voltmeter 7, the contacted track is found, but the position in the circumferential direction is unknown, and accurate evaluation cannot be performed. Further, the waveform at the time of contact is shocked, whereas the peak value is not known because the effective value voltage is read, and correct data directly linked to the evaluation of the actual surface state cannot be obtained. On the other hand, in the inspection method using the oscilloscope 8, it is possible to specify the position in the circumferential direction from the timing with the trigger signal, but it is enormous to measure all cylinder positions. Lack of practicality in terms of points. The technical problem of the present invention is to solve such problems in the conventional inspection method, to enable the peak value of the spike-like waveform output from the detecting means to be accurately detected, and to cause contact. It is intended to accurately identify the position not only in the track direction but also in the circumferential direction so that the inspection result such as the contact state can be grasped two-dimensionally. FIG. 1 is a diagram showing an outline of an apparatus used in the method of the present invention for explaining the basic principle of the method of inspecting a magnetic disk medium according to the present invention. D is a magnetic disk device, which includes a magnetic disk, a magnetic head,
It is composed of an actuator for driving a magnetic head, a control unit for these, and the like. M is a memory means and C is a computer. A detection signal of a detection means for inspecting a magnetic disk, such as a piezoelectric element, is inputted to the memory means M from the control section of the magnetic disk device. Also, seek information, that is, cylinder information is used as information indicating the position of the detecting means in the cylinder direction, and sector information is used as information indicating the position of the detecting means in the circumferential direction. Further, access state information indicating the access state of the detecting means is used. By inputting these pieces of information into the memory means M, collecting them, and processing them by the computer C, the state of the magnetic disk can be expressed two-dimensionally and evaluated. In the detection signal of the detection means, for example, a noise component is cut by a filter, only the frequency peculiar to the detection means is passed to extract a spike waveform, and the magnitude of this spike waveform is detected by a comparator to obtain only the peak value. It is obtained by outputting as level information. Cylinder information, which is track information, is
For example, it can be obtained by inputting the track cross pulse and the seek direction information generated when the track crosses from the control unit of the magnetic disk device D to the cylinder counter and counting. Further, the sector information can be obtained, for example, by inputting an index pulse and a sector pulse from the control unit of the magnetic disk device D to a sector counter and counting. Furthermore, the access state information can be obtained by inputting information indicating the acceleration state, the deceleration state, or the on-track state at the time of seek from the control unit of the magnetic disk device D, for example. In the present invention, when the piezoelectric element comes into contact with the surface of the magnetic disk or a detection signal is output, it is input to the memory means M, and the position of the magnetic head on the cylinder at that time is specified by the cylinder information. It The position in the circumferential direction can be specified by the sector information. The access state information is information indicating whether the seek of the magnetic head is in an accelerating state, a decelerating state, an on-track state, or the like. The information is input to the memory means M and collected, and the computer C It is processed. Therefore, the inspection result can be grasped and evaluated in a two-dimensional manner, and the position of the defect or the like can be accurately detected in which sector of the magnetic disk on which cylinder the protrusion exists. . Further, by using the access state information, the relationship between the generation of the detection signal and the operation of the magnetic disk device is clarified. Next, how the method for inspecting a magnetic disk medium according to the present invention is actually embodied will be described with reference to FIG. FIG. 2 is a diagram showing a system of an apparatus used in an embodiment of a magnetic disk medium inspection method according to the present invention. This system has a comparator 9 in order to obtain output level information of the piezoelectric element for detecting the mechanical shock received by the magnetic head in the magnetic disk device D. A bandpass filter 10 and an amplifier 11 are provided between the comparator 9 and the magnetic disk device D. Further, it has a sector counter 12 for obtaining sector information for specifying the head position and a cylinder counter (up / down counter) 13 for obtaining cylinder information. Further, these three pieces of information and access state information are collected in the memory element M and processed by the computer C. Since the structure of the detecting means such as the magnetic head and the piezoelectric element in the magnetic disk device D is the same as that of the conventional example shown in FIG. 4, it will be described with reference to FIG. Now, when the magnetic disk 1 shown in FIG. 4 rotates, the magnetic head 2 floats. However, the magnetic head 2 collides with the surface of the magnetic disk 1 due to protrusions on the surface of the magnetic disk 1 or unstable floating of the magnetic head 2. I have something to do.
At this time, the piezoelectric element 6 outputs a spike-like waveform in response to this collision, but generally has a waveform with many noise components. Therefore, a bandpass filter 10 and an amplifier 11 which pass and amplify only the natural frequency of the piezoelectric element 6 are provided to remove noise components and only the spike waveform generated when an actual collision is output to the comparator 9. To do. The comparator 9 detects the magnitude of this spike waveform. For example, the magnitude is divided into 5 steps and the peak value is output as the level information IL,
The memory load signal SL is output to the memory element M when the minimum level among the five levels at the fall of the spike waveform is crossed. The sector signal and the cylinder signal are extracted from the magnetic disk device D in order to know the timing when the spike waveform is output, that is, when the magnetic disk 1 and the magnetic head 2 come into contact with each other. It is necessary to collect information while the actuator is actually operating. Normally, the magnetic disk device D does not have a built-in register, so a sector counter 12 and a cylinder counter 13 are provided. The sector counter 12 outputs sector information Is indicating which position on the circumference the contact point is, and uses the sector pulse as a clock signal.
Clear with index pulse. The cylinder counter 13 outputs cylinder information Ic, which is position information of the contact point in the track direction, and is basically an up / down counter, and a track cross pulse generated when the track crosses a clock signal. The up / down is switched according to the access direction information at the time of seek. Further, from the magnetic disk device D, the control for moving the actuator in order to know the state of the actuator as the access state information 1a, that is, the acceleration state, the deceleration state, or the on-track state. Take out the control signal of the circuit. These four pieces of information, namely level information I
L, sector information Is, cylinder information Ic, and access state information 1a are simultaneously stored in the memory element M by the memory load signal SL described above. After that, in the computer C, information is periodically fetched from the memory element M by software and expressed as two-dimensional information. It is obtained by entering. FIG. 3 is a diagram showing a system of an apparatus used in another embodiment of the magnetic disk medium inspection method according to the present invention. In this system, in order to perform efficient contact monitoring, the number of monitoring devices is increased to 16 at maximum, and the entire medium evaluation is performed in parallel. However, as shown in Fig. 2, the basic configuration for processing various information is only one set, so the piezoelectric elements Po to Pf attached to the head of each device.
The analog signal output from is selected by the analog scanner 14, and also the index pulse, sector pulse, track cross pulse, which becomes the position information of the head of each device,
The seek direction information and the access state information are selected by the digital scanner 15, and this selection is controlled by the computer. The contact monitoring of the entire surface of the medium can be performed by sequentially performing the same operation as described above for each device. As described above, according to the present invention, a vibration waveform having a specific frequency or more is extracted from the signal output from the detection means for detecting the contact between the magnetic disk medium and the magnetic head. The position where the vibration waveform is extracted on the magnetic disk medium is specified from the track information and the sector information obtained from the magnetic disk medium, and the vibration waveform is extracted from the access state information indicating the state of the magnetic head. Since the seek state at that time was the acceleration state, the deceleration state, or the on-track state was specified, accurate data directly linked to the evaluation of the actual surface state can be obtained. Therefore, the contact position can be specified, the occurrence frequency, and the contact strength can be displayed two-dimensionally.
Later evaluation can be performed easily and accurately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an outline of an apparatus used in the method of the present invention for explaining the basic principle of a method of inspecting a magnetic disk medium according to the present invention. FIG. 2 is a diagram showing a system of an apparatus used in an embodiment of a magnetic disk medium inspection method according to the present invention. FIG. 3 is a diagram showing a system of an apparatus used in another embodiment of the magnetic disk medium inspection method according to the present invention. FIG. 4 is a diagram showing an outline of a conventional magnetic disk medium inspection method. [Explanation of Codes] 1 magnetic disk medium 2 magnetic head 6 piezoelectric element (detection means) IL level information (vibration waveform extracted from output signal of detection means) Ic cylinder information (track information) Is sector information 1a access state information

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Claims (1)

What is claimed is: 1. A method for inspecting a contact state between a magnetic disk medium and a magnetic head, the method comprising: detecting the contact state between the magnetic disk medium and the magnetic head. A step of extracting a vibration waveform having a natural frequency or more from the signal output from the output signal, and a position where the vibration waveform is extracted on the magnetic disk medium from track information and sector information obtained from the magnetic disk medium. And a step of identifying from the access state information indicating the state of the magnetic head, whether the seek state when the vibration waveform was extracted was an accelerating state, a decelerating state, or an on-track state. A method for inspecting a magnetic disk medium, comprising: