JPH03238622A - Magnetic head abnormality check system for magnetic disk certifier - Google Patents

Abstract

PURPOSE:To enable the treatment of a magnetic head to execute before the finish of medium inspection by connecting a read-out circuit successively to a common check circuit, and calculating the mean value of test signal voltage of every four tracks for each magnetic head, and suspending the medium inspection when the mean value is out of a reference range. CONSTITUTION:A switch 6 is connected to the read-out circuits 3c of four pieces of the magnetic heads 2a of a certifier, and the common head abnormality check circuit 7 to check the abnormal state of each magnetic head 2a is provided. Each read-out circuit 3c is connected successively to the checking circuit 7 by switching the switch 6 for every seeking of each magnetic head 2a by the control and the processing of a microprocessor 4, and the mean value of the test signal voltage read out by each magnetic head 2a is calculated successively in parallel with the detection of the defect of the recording medium of each area. Thus, if the magnetic head is in an abnormal state according to checking, the medium inspection is suspended, and the abnormal state can be restored immediately by executing the treatment such as the exchanging of the magnetic head and the like.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for checking abnormalities in a magnetic head for inspection used in a magnetic disk certifier, and more particularly, to a method for checking the abnormality of a magnetic head for inspection used in a magnetic disk certifier. This is a method of checking the abnormal state of the magnetic head in parallel.

[Prior Art] The quality of hard magnetic disks, which are frequently used as information recording media, is inspected by a magnetic disk certifier during the production process. During inspection, a test signal of an appropriate frequency is written and read out to perform inspection on various items. Inspection is performed for each of the many trunks provided on the disk, and requires a considerable amount of time. In order to shorten this time and improve inspection efficiency, a two-area, double-sided parallel inspection method is used. .

FIGS. 2(a) to 2(d) show an outline and testing sequence of a magnetic disk certifier using a two-area, double-sided parallel testing method. In Figures (a) and (b), the range of the recording medium of the magnetic disk 1 is divided into an outer peripheral area 1a and an inner peripheral area 1b, and a magnetic head section 2-I is provided for the front and back surfaces of each area, respectively.

2-2 is provided. The two magnetic heads (HDAt, A2) 2a-1 of the magnetic head unit 2-1 are connected to the two magnetic heads (HDAt, B2) 2a-1 of the magnetic head unit 2-2 by the carriage mechanism 2b-1. 2 seeks tracks on both sides of the outer peripheral area 1a and the inner peripheral area 1b, respectively, by the calison mechanism 2b-2. In Figure (C), four sets of the same inspection section 3 consisting of an AMP 3a and a disk defect detection circuit 3b are provided for each magnetic head, and each magnetic disk 1 is rotated under the control of a microprocessor 4. Tracks in the area are sought, and under the control of the controller 5, test signals are read out and read out in parallel for these tracks. Figure (d) shows the sequence of medium inspection, and the index IND indicating the reference point of the rotation angle of the magnetic disk is obtained separately.
EX) signal, each time the magnetic disk rotates, tracks on both sides of each area are first sought, and each defect detection circuit 3b writes a test signal to each track. Various items are then inspected by the defect detection circuit 3b. In the illustrated average voltage measurement, the peak value of the test signal is detected and the average value thereof is calculated by the microprocessor 4. A code missing (Mis) error test and a peak value modulation (MOD) test are performed using this average value as a reference, and when these are completed, the test signal is erased, and then the code error is tested. be done. As described above, the inspection of one track is completed after five revolutions of the disk, and the next track is sequentially sought, and the above sequence is repeated to inspect all the tracks.

[Problem to be Solved] In the above-mentioned medium inspection, it is of course assumed that there is no abnormality in the function or performance of the magnetic head itself, and that it operates while floating at a predetermined height. On the other hand, in the conventional inspection method, J constant L is measured for each area, and the above average value voltage is measured, and if this is within a certain standard range, it is judged as good. In other cases, a method is used in which the operating state of the magnetic head is made abnormal. However, since there are so many trunks, checking one track per area cannot be expected to be effective. In addition, abnormal conditions are only discovered from the inspection data after the inspection is completed, and even with the above-mentioned two-area, double-sided inspection method, inspection takes a considerable amount of time, so this discovery is too late and the inspection data is wasted. Not only that, but also the inspection efficiency was low. on the other hand,
Recently, small and lightweight thin film heads have been used, which operate by floating at an extremely small height above the surface of the magnetic disk using air 70, and therefore abnormal conditions often occur during inspection. Therefore, it is necessary to constantly check the operating status and, if an abnormality occurs, to interrupt the inspection and immediately correct the abnormality.

The present invention has been made in view of the above, and an object of the present invention is to provide a method for constantly checking the operational status of a magnetic head during a medium inspection using a magnetic disk certifier, and immediately stopping the inspection in the event of an abnormality. It is something to do.

[Means for Solving the Problems] The present invention is a method for checking an abnormality of a magnetic head in a certifier that tests a recording medium of a magnetic disk using a two-area double-sided parallel method. A switch is connected to the readout circuits of the four magnetic heads of the certifier, and a common check circuit is provided to check the abnormal state of each magnetic head. Under the control and processing of a microprocessor, each readout circuit is sequentially connected to a check circuit by switching a switch for each seek of each magnetic head.
In parallel with defect detection for the recording medium in each area, the average value of the test signal voltages read by each magnetic head is sequentially calculated. When this average value is within the reference range, the magnetic head is determined to be normal, and when it is outside the reference range, it is determined that the magnetic head is in an abnormal state and the medium inspection is stopped.

[Function] In the above abnormal state of the magnetic head, in the evening ceremony,
In parallel with the medium inspection by the two-area double-sided parallel type certifier, a switch is changed by the microprocessor and the readout circuits are sequentially connected to a common check circuit every 7 times the magnetic head is read. The average value of the test signal voltage is calculated for every four tracks for the head. When this is within the reference range, the magnetic head is determined to be normal; when it is outside the reference range, the magnetic head is determined to be in an abnormal state, and the medium inspection is stopped. This intermediate correction allows measures such as replacing the magnetic head to be taken without waiting for the completion of the medium inspection, and the abnormal state is immediately recovered. Note that no particular time is required to check the magnetic head, and the medium inspection can be performed in the same amount of time as in the past.

[Embodiment FIG. 1(a) shows a magnetic head abnormality checker according to the present invention,
A block diagram of the evening style embodiment is shown in Figure (b).
) is a check sequence for this. Diagram (a)
As in FIG. 2(C) described above, there are four magnetic heads (HDAI, HDA2).

An inspection unit 3 including an AMP 3a and a disk defect detection circuit 3b is provided for the HDBI, HDB2) 2a. Under the control of the microprocessor 4, each magnetic head seeks the fith track of each IJ and A, and test signals are written and read for each, and the disk defect detection circuit 3b is controlled by the controller 5. A signal is applied, and a medium test is performed according to the test sequence shown in FIG. 2(d). In contrast, in the present invention, the switch 6 and the head abnormality check circuit 7 common to each magnetic head 2a are provided, and the switch 6 is connected to each AMP 3.
It is connected to the four readout circuits 3c of a. Under the control 1 of the microprocessor 4, the switch is changed over each time the magnetic head is turned, and the readout circuits are sequentially connected to the check circuit 7.

In FIG. 1(b), four magnetic heads (HDAI,
HDA2. HDBt, HDBz) seeks each trunk in numerical order (from arbitrary TRNn n in the figure) and performs a medium test (TRTST, ) for each trunk.
Assume that these are performed in parallel.

In parallel, the test signal voltages read by each magnetic head are sequentially input to the check circuit 7 for each seek, and the average value is calculated by the microprocessor 4 to check the operating state (HDCH). . In this case, since there are four magnetic heads, the status of each magnetic head is determined every four trunks (HDCH). When the test signal voltage read by each magnetic head is within the reference range,
“OK” is displayed for (HDCH). The figure shows HDA2 in the Nil (n + 1) track.
This indicates that the average value of HbA2 is outside the standard range, HbA2 is in an abnormal state "NG", the medium inspection is corrected by stopping the rotation of the magnetic disk, etc., and HDA2 is immediately replaced. There is.

Note that when an NG (abnormal) magnetic head is detected,
The test disk will be tested again starting from the first test.

[Effects of the Invention] As is clear from the above explanation, in the magnetic head abnormality check method according to the present invention, the magnetic head is The operating status of the media is checked every four tracks, and the medium is inspected at the same time as in the past. If the check indicates that the medium is in an abnormal state, the medium test is stopped, and the abnormal state can be immediately recovered by taking measures such as replacing the magnetic head. The effect of eliminating the decline is significant.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are block diagrams and check sequence diagrams in an embodiment of the magnetic head abnormality check method for a magnetic disk certifier according to the present invention, and FIGS. 2(a), (b), ( c) and (d) are
FIG. 2 is a schematic diagram and a medium inspection sequence diagram of a magnetic disk certifier using a two-area, double-sided interval time inspection method. 1...Magnetic disk, la...Outer area,
1b...Inner peripheral area, 2...Magnetic head section,
2a... Magnetic head, 2b... Carriage mechanism, 3... Inspection section, 3a... AMP13
b...Disk defect detection circuit, 3c...Reading circuit, 4...Microprocessor, 5...Controller, 6...Switch, 7
...Head abnormality check circuit.

Claims (1)

[Claims] (1) In a certifier that inspects magnetic disk recording media using a two-area, double-sided parallel method, switches connected to the readout circuits of four magnetic heads and a common unit that checks abnormal conditions of each magnetic head. A check circuit is provided, and under the control and processing of a microprocessor, the switch is switched every time each magnetic head seeks, and the readout circuit is sequentially connected to the check circuit, thereby detecting defects in the recording medium in each area. In parallel, the average value of the test signal voltages read by each of the magnetic heads is calculated, and when the average value is within a reference range, the magnetic head is determined to be normal, and when it is outside the reference range, the average value is determined to be normal. A magnetic head abnormality check method for a magnetic disk certifier, characterized in that testing of the recording medium is stopped when an abnormal state is detected.