JPH0762943B2 - Defect-free track test method - Google Patents

Description

DETAILED DESCRIPTION [Overview] During a servo track writing process, an error detection of a defect-free track is performed with priority, and when an error is detected in a defect-free track, the servo track is rewritten immediately.
The position of the data track can be shifted by a small distance in the radial direction of the magnetic disk, and the number of manufacturing steps of the magnetic disk device can be reduced.

[Industrial application field]

The present invention relates to a magnetic disk used in a magnetic disk device, and more particularly to a defect-free track test method capable of testing a defect-free track required for a magnetic disk and shortening a process for selecting a good product.

The magnetic disk device is the most accessible auxiliary storage device of a computer system because of its random accessibility, short access time, relatively low price per bit of information, and relatively high reliability of information. It is widely used and is also used for storing various data, for example, a program for starting an operating system (OS).

By the way, the magnetic disk device is provided with a magnetic disk composed of several magnetic disk disks according to the storage capacity, and generally both surfaces thereof are used as data recording surfaces, and a magnetic head is provided for each data recording surface.

Therefore, in the data storage area of the magnetic disk device, track numbers are given to the respective cylinders, and the magnetic heads are simultaneously positioned on all the tracks of the same cylinder. Then, this magnetic head is controlled so as to be simultaneously positioned from the home position, which is positioned at the initial stage, to each track having a target cylinder number.

As described above, the magnetic disk device is also used for storing the program for starting the operating system, and is loaded into the main memory by the initial program loading. However, in order to shorten the loading time, it is normally stored in the cylinder track near the home position. I try to remember.

On the other hand, a magnetic disk is prepared by mixing acicular magnetic particles γ-Fe ₂ O _{3 and the} like with a binder and coating it on a light alloy disc. However, in terms of manufacturing cost, it is practically impossible at present.

Therefore, after assembling as a magnetic disk device, for example, the presence or absence of a defective bit is inspected in track units, the place where the defective bit is found is identified as a defective area, and the next area is used without using it. Is used.

However, in many cases, for example, a defect-free track having no defective bits is required near the home position due to the reason why the program load time needs to be shortened or the customer's request. When multiple defect-free tracks are required, it is necessary that multiple tracks belonging to the same cylinder be defect-free, and it is generally an important condition that the cylinder tracks near the home position are defect-free tracks. There is.

[Conventional technology]

Since the magnetic disk positions the magnetic head in the target cylinder, a servo track is provided for each cylinder,
Servo information is written in this servo track, and seek control is performed based on this servo information. Therefore, the magnetic disk manufacturing process includes a servo track writing process.

Here, in order to satisfy the above-described requirements for a defect-free track, conventionally, after the magnetic disk device is assembled, the servo track writing is performed and the error inspection of all tracks is performed in the next error inspection step. In this error inspection step, error detection of a defect-free track is also performed, and the quality of the defect-free track is determined.

If an error occurs from a defect-free track and it is determined that there is a defective bit, the position of the servo track is shifted, the servo track writing is performed again, and the error inspection of all tracks is performed. Then, the quality of the defect-free track is determined, and if there is a defective bit, the assembled magnetic disk device is disassembled and the disk corresponding to the defective track is replaced. Then, the above steps are repeated from the beginning.

[Problems to be solved by the invention]

As described above, conventionally, after the servo track writing is completed, the quality of the defect-free tracks is judged at the time of error inspection of all tracks. Therefore, if a defective bit is found in the defect-free track, the position of the servo track is shifted. , Servo track writing is repeated, but even in this case, it takes a lot of man-hours to check all the tracks for errors, and in the worst case it is necessary to replace the magnetic disk disk, so disassemble the assembled magnetic disk device. Therefore, there is a problem that many man-hours are required.

In view of such a problem, the present invention determines whether a defect-free track is good or bad at the same time as writing the servo track, and when a defective bit is detected, the servo track is immediately rewritten to determine the position of the data track on the magnetic disk. A slight distance is shifted in the radial direction, and servo track writing and defect-free track quality determination are performed again.

[Means for solving problems]

 The drawing is a block diagram of a circuit showing an embodiment of the present invention.

Reference numeral 1 is a processor for controlling the main control circuit 2, 2 is a main control circuit operated under the control of the processor 1, 3 is a laser length measuring device for measuring the moving distance of the voice coil motor 5, and 4 is a voice coil motor 5 and a magnetic disk. It is a mechanism control circuit that drives a motor that rotates the.

5 is a voice coil motor for driving the head access mechanism 6, 6 is a head access mechanism for positioning the magnetic heads 7 to 9 at predetermined positions, 7 and 8 are magnetic heads for data, 9 is a magnetic head for servo, and 10 to 12 Is the recording surface of the magnetic disk,
Reference numeral 13 is a motor for rotating the magnetic disk.

The main control circuit 2 detects the amount of movement of the voice coil motor 5 by the laser length measuring device 3 and controls the mechanism control circuit 4 to move the voice coil motor 5 by a predetermined amount, and the head access mechanism 6 is used for servo control. The magnetic head 9 writes servo information on the recording surface 12 of the magnetic disk, and the magnetic heads 7 and 8 for data are used to detect the presence / absence of defective bits in a defect-free track, and to detect defects every time the servo track is written. The configuration is such that the quality of the track is determined.

[Operation] With the above configuration, when a defective bit is detected in a defect-free track, the position of the servo track can be immediately shifted to determine whether or not the defect-free track is defective.

〔Example〕

In the figure, a main control circuit 2 is a voice coil motor 5 measured by a laser length measuring device 3 according to an instruction from a processor 1.
The positions of the magnetic heads 7 to 9 are determined from the position of, and the mechanism control circuit 4 is controlled to position the magnetic head 9 at the position of the track where the servo information is written.

That is, the mechanism control circuit 4 supplies a drive current to the voice coil motor 5, carries the head access mechanism 6, and moves the magnetic heads 7 to 9 to predetermined positions. Further, the motor 13 is driven to rotate the magnetic disk recording surfaces 10 to 12.

The main control circuit 2 supplies servo information to the servo magnetic head 9 via the head access mechanism 6, writes servo tracks on the magnetic disk recording surface 12, and causes the data magnetic heads 7 and 8 to perform magnetic recording. Disc recording surface
After writing error check data in 10 and 11, respectively, the data magnetic heads 7 and 8 are sequentially switched to detect defective bits in a defect-free track.

When a defective bit is detected on a defect-free track, the main control circuit 2 immediately erases the written servo information (it may be replaced by erasing by rewriting), and also erases the error check data (re-writing). (Erasing by writing may be substituted), and the first servo track position is moved in the radial direction of the magnetic disk recording surface 12 by a small distance, and after performing the servo track writing and the error check data writing again as described above, This error check data is read to determine the quality of a defect-free track.

〔The invention's effect〕

As described above, according to the present invention, the quality of defective tracks is determined every time a servo track is written. Therefore, it is not necessary to wait for the determination of the quality of non-defective tracks until writing to all servo tracks is completed. The number of man-hours for manufacturing the device can be reduced.

[Brief description of drawings]

 The drawing is a block diagram of a circuit showing an embodiment of the present invention. In the figure, 1 is a processor, 2 is a main control circuit, 3 is a laser length measuring device, 4 is a mechanism control circuit, 5 is a voice coil motor, 6 is a head access mechanism, 7-9 are magnetic heads, 10-12 are magnetic. Disk recording surface, 13 is a motor.

Claims (1)

[Claims] 1. A position detecting means (3) for detecting the position of a magnetic head, and based on the position of the magnetic head detected by the position detecting means (3), the magnetic head is moved to a predetermined position on a magnetic disk. Positioning, writing servo information in the servo recording portion of the magnetic disk, writing error checking data in the data recording portion, and then reading the error checking data by the magnetic head, and recording the data. In a device provided with control means (1) (2) for detecting a defect in a track of a part, the error check data written in each track at a predetermined position of the data recording part is read to read the track. When the defect of the magnetic head is detected, the position of the magnetic head is shifted in the radial direction of the magnetic disk, the servo information is written again in the servo recording section, and the data is recorded. No defective track testing method characterized in that a defect detection of the track after performing writing of data for error checking on each track of the recording unit.