JP2588038B2 - Magnetic head abnormality check method of magnetic disk certifier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a system for checking an abnormality of a magnetic head for inspection used in a magnetic disk certifier, and more specifically, to a method for checking a medium of a magnetic disk. This is a method for checking the abnormal state of the magnetic head.

2. Description of the Related Art The quality of a hard magnetic disk, which is frequently used as an information recording medium, is inspected by a magnetic disk certifier in a production process. In the inspection, a test signal of an appropriate frequency is written, read out, and various items are inspected. The inspection is performed for each of a large number of tracks provided on the disk and requires a considerable amount of time. In order to shorten the inspection time and improve the inspection efficiency, a two-sided area parallel inspection method is used. .

2 (a) to 2 (d) show an outline and an inspection sequence of a magnetic disk certifier using an area two-sided double-sided parallel inspection method. 1A and 1B, the range of the recording medium of the magnetic disk 1 is an outer peripheral area 1a and an inner peripheral area.
The magnetic heads 2-1 and 2-2 are provided on the front and back surfaces of each area, respectively. Two magnetic heads (HDA _1, A ₂₎ of the magnetic head unit 2-1 by 2a-1 is a carriage mechanism 2b-1, also the magnetic head unit 2-2
The two magnetic heads (HDB ₁ , B ₂ ) 2a-2 seek the tracks on both surfaces of the outer peripheral area 1a and the inner peripheral area 1b by the carriage mechanism 2b-2. In FIG. 3C, for each magnetic head, four sets of the same inspection unit 3 including an AMP 3a and a disk defect detection circuit 3b are provided, and the magnetic disk 1 is rotated under the control of the microprocessor 4 to change the track of each area. The seek is performed, and under the control of the controller 5, writing / reading of test signals to / from these is performed in parallel. FIG. 4D shows a sequence of a medium inspection. In accordance with a separately obtained index (INDEX) signal indicating a reference point of the rotation angle of the magnetic disk, the tracks on both sides of each area are first recorded for each rotation of the magnetic disk. The seek is performed, and a test signal is written to each track by each defect detection circuit 3b. Then defect detection circuit
Various items are inspected by 3b. In the illustrated average voltage measurement, the peak value of the test signal is detected, and the average value is calculated by the microprocessor 4. Based on the average value, a code missing (MIS) error test and a peak value modulation (MOD) test are performed. When these tests are completed, the test signal is erased, and subsequently, a code output (EXT) error is generated. Tested.
As described above, the inspection of one track is completed after five rotations of the disk, the next track is sequentially sought, and the above sequence is repeated to inspect all the tracks.

[Problem to be Solved] In the medium inspection described above, it is naturally assumed that there is no abnormality in the function and performance of the magnetic head itself, and that the magnetic head operates in a state of floating at a predetermined height. On the other hand, in the conventional inspection method, an appropriate one track is selected for each area, and the average voltage measurement is performed.
A method has been adopted in which the magnetic head is determined to be good when it is within a certain reference range, and otherwise the operating state of the magnetic head is abnormal. However, the number of tracks is very large, and the effect of checking cannot be expected if each area has one track. In addition, the abnormal state is first detected by the inspection data after the inspection is completed, and the inspection takes a considerably long time even by the above-described two-area two-sided simultaneous inspection method. In addition, there is a disadvantage that the inspection efficiency is reduced. On the other hand, recently, a thin and lightweight thin film head has been used, and it operates by flying to an extremely small height from the surface of the magnetic disk by air flow, so that an abnormal state often occurs during inspection. Therefore, it is necessary to constantly check the operation state, and in the case of abnormality, stop the inspection and immediately recover from the abnormality.

The present invention has been made in view of the above, and it is an object of the present invention to provide a method of continuously checking the operating state of a magnetic head during a medium inspection by a magnetic disk certifier and immediately stopping the inspection if an abnormality is found. Things.

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

[Operation] In the above-described abnormal state check method of the magnetic head, the switch is switched by the microprocessor for each seek of the magnetic head, and the read circuit is operated in parallel with the medium inspection by the certifier of the area two-part double-sided parallel method. The magnetic heads are sequentially connected to a common check circuit, and the average value of the test signal voltage is calculated for each magnetic head every four tracks. When this is within the reference range, the magnetic head is determined to be normal, and when it is outside the reference range, the magnetic head is determined to be in an abnormal state, and the medium inspection is stopped. With this suspension, measures such as replacement of the magnetic head can be performed without waiting for the end of the medium inspection, and the abnormal state is immediately recovered. No special time is required for checking the magnetic head, and the medium inspection is performed in the same time as the conventional one.

Embodiment FIG. 1A shows a block diagram of an embodiment of a magnetic head abnormality check system according to the present invention, and FIG. 1B shows a check sequence for this. In FIG. 2A, as in FIG. 2C described above, four magnetic heads (HDA ₁ , HDA ₂ , HDB ₁ , HDB ₂ ) 2a are AMP3a driven.
And an inspection unit 3 including a disk defect detection circuit 3b. Under the control of the microprocessor 4, each magnetic head sequentially seeks a track in each area, writing and reading of a test signal are performed for each, and a control signal is given from the controller 5 to the disk defect detection circuit 3b. Then, the medium inspection is performed according to the inspection sequence shown in FIG. On the other hand, in the present invention, a switch 6 and a head abnormality check circuit 7 common to each magnetic head 2a are provided, and the switch 6 is connected to four read circuits 3c of each AMP 3a. Under the control of the microprocessor 4, the switch is switched for each seek of the magnetic head, and the read circuits are sequentially connected to the check circuit 7.

In FIG. 1B, four magnetic heads (HDA ₁ , HDA _1
2 , HDB ₁ , HDB ₂ ) seeks each track in numerical order (from any TR No. n in the figure), and media inspection (TRTST.) For each track is performed in parallel.
In parallel with this, the test signal voltage read by each magnetic head is sequentially input to the check circuit 7 for each seek, and the average value is calculated by the microprocessor 4 to check the operation state (HDCH). . In this case, since there are four magnetic heads, the state of each magnetic head is (HDCH) every four tracks. When the test signal voltage read by each magnetic head is within the reference range, “OK” is displayed for (HDCH). The figure shows the case where the average value of HDA ₂ in the track of No. (n + 1) is out of the reference range. It is assumed that HDA ₂ is in the abnormal state “NG”, and the medium inspection is stopped by stopping the rotation of the magnetic disk or the like. It has been shown that HDA ₂ will be replaced immediately. NG
When an (abnormal) magnetic head is detected, the test of the test disk is performed again from the first track.

[Effects of the Invention] As is apparent from the above description, in the magnetic head abnormal state checking method according to the present invention, the area 2
In parallel with the medium inspection of the magnetic disk by the split-sided two-sided parallel certifier, the operating state of the magnetic head is checked every four tracks, and the medium inspection is performed in the same time as the conventional one. If an abnormal state is detected by the check, the medium inspection is stopped, and the abnormal state can be immediately recovered by taking measures such as replacing the magnetic head. The effect of eliminating the drop is significant.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a block diagram and a check sequence diagram in an embodiment of a magnetic disk abnormality check system of a magnetic disk certifier according to the present invention, and FIGS. 2 (a), (b) and (c). ) And (d)
FIG. 3 is a schematic diagram of a magnetic disk certifier using an area two-sided simultaneous double-sided inspection method and a medium inspection sequence diagram. 1 ... magnetic disk, 1a ... outer area, 1b ... inner area, 2 ... magnetic head section, 2a ... magnetic head, 2b ... carriage mechanism, 3 ... inspection section, 3a ... AMP, 3b ... Disk defect detection circuit, 3c readout circuit, 4 microprocessor, 5 controller, 6 switch, 7 head abnormality check circuit.

Claims (1)

(57) [Claims] 1. A certifier for inspecting a recording medium of a magnetic disk by an area two-part double-sided parallel system,
A switch connected to the read circuits of the four magnetic heads, and a common check circuit for checking an abnormal state of each magnetic head are provided. The read circuit is sequentially connected to the check circuit by switching the switch, and the average value of the test signal voltages read by the magnetic heads is determined in parallel with the detection of the defect of the recording medium in each area. A magnetic disk certifier, wherein the magnetic head is normal when the average value is within a reference range, and the inspection of the recording medium is stopped as an abnormal state when the average value is outside the reference range. Magnetic head abnormality check method.