JPH0245157B2 - JIKIDEISUKUBAITAINOKETSUKANKENSAHOHO - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for inspecting defects in magnetic disk media, and more particularly, the present invention relates to a method for inspecting defects in magnetic disk media. This invention relates to a method for inspecting defects on magnetic disk media that can be carried out continuously over the entire circumference.

[Prior Art] In general, a defect inspection device for magnetic disk media is
It is composed of a magnetic disk drive device, a magnetic head, a write circuit, a read circuit, a defect detection circuit, and a control circuit that controls all of these components, including a microprocessor and memory. Conventionally, the defect inspection method for this type of device is to write a data pattern (hereinafter referred to as a test pattern) for defect inspection on the disk medium by going around the track once under the control of a control circuit, and then immediately write the next data pattern. This is done by reading out test patterns in cycles and detecting defective areas for items such as drop-out, drop-in, amplitude, modulation, resolution, etc. from the written contents and read results.This is sequentially repeated for all tracks on the magnetic disk medium and continuously I'm going to the target.

When a defective part is detected continuously according to the track, the magnetic head is switched from a write state to a read state, or vice versa.
This is performed based on an index signal which is a rotational reference position signal for one revolution obtained by detecting a physical index mark indicating a rotational reference position.

FIG. 4 is a block diagram of the main parts of this type of conventional disk medium defect inspection apparatus. The write pattern required for inspection is generated by the write pattern generation circuit (WRPG) 7, and the write pattern is generated by the write amplifier (WRA).
5 and a head with a write/read switching circuit, etc.
Magnetic head (HD) 2 via IC (HDIC) 3
A test pattern is written to the magnetic disk medium (DISK) 1, and then the written test pattern is read out again through the magnetic head 2, head IC 3, and read amplifier (RDA) 6, and the read data is sent to the defect detection circuit (RDDET). ) 8, and the obtained defect detection data is sent to the microprocessor 2.
A control circuit (TCNTRL) 20 having a memory 22 and the like receives the data and processes the data in a predetermined manner.

Here, control such as switching of the write state and read state of the magnetic head 2 is performed by a head switching control circuit (HCNTRL) 4. As shown, the head switching control circuit 4 is controlled in accordance with control signals from the control circuit 20, and also generates other control signals necessary for test control to control various internal circuits.

The control circuit 20 is a defect inspection data processing circuit, and usually includes a microprocessor 21 and a memory 2.
2, etc., which controls the head switching control circuit 4, sends a start signal, etc. to the write pattern generation circuit 7 in response to an index signal 9, which will be described later, to control writing of the test pattern, and controls the write pattern generation circuit 8. The inspection processing program 22a for this purpose is installed in the memory 22. The microprocessor 21 executes this inspection processing program 22.
By executing step a, various processes are performed on the measurement data such as defects obtained from the magnetic disk medium 1, including the above operations.

FIG. 2a is a conventional timing chart of the defective part detection operations that are performed successively as described above.
9 is the index signal, 10 is the head write/
The read state switching time (GAP), 11 is the write state (WR), 12 is the read state (RD), and 13 is the time for one track round. As you can see from this figure,
Head switching requires a short but finite amount of time. Moreover, it is longer than the generation period of the index signal.

Here, the index signal 9 is transmitted to the magnetic head 2.
It may be detected from an index pattern written in advance on a track or the like, or it may be obtained by reading out the index pattern via a separately provided servo head. Furthermore, the information may be obtained by detecting a specially provided index hole or the like in a floppy disk or the like using a special detection means. The various means for obtaining these index signals may be any means as long as they detect an index mark indicating the rotational reference position of the magnetic disk 1, in other words, one rotation of the track. Since this is already well known, its explanation will be omitted.

[Problem to be Solved] Now, as can be understood from the timing chart in FIG.
It is being carried out in That is, the same index signal 9 that appears one cycle after the index signal 9 that is the starting point becomes the end point, and in order to continue the processing, the index signal 9 that becomes the end point is treated as the starting point of the next operation. There is.

Now, if test patterns are read and written continuously at the timing shown in Figure 2a,
During this period, a head state switching time of 10 is required. Therefore, a period during which no test pattern is written or read exists as a head state switching period. Therefore, even if a defect exists in the media portion corresponding to this period, it will not be detected.

This switching time 10 (the proportion is exaggerated in Fig. 2a and the same in Figs. 2b and 3) is actually very small compared to the one-round time 13. However, in the case of high-density recording, it corresponds to several tens of bits or more. Therefore, it has become impossible to ignore this part in high-density recording magnetic disk media.

That is, in defect inspection of high-density recording magnetic disk media, among the test patterns, test patterns that should be written or read within the short time required for this switching cannot be handled as inspection. A problem arises in that even if there is a defect near the position where the index signal 9 is generated, the defect is not detected and is overlooked.

This is because the index signal at the end point that comes one round later is treated in the same way as the start point of the next operation. Therefore, in order to avoid the above-mentioned problem, the index signal at the end point and the index signal at the next starting point are separated, as shown in FIG. 2b.

This starts with index signal 9 and writes one round of pattern data with index signal 9 one round after that as the end point, and the next reading is as follows:
Instead of using the index signal 9 set as the end point continuously, the index signal 9 that comes after it is used, and the index signal 9 is used as the starting point to perform one round all over.
As in the previous example, head state switching (switching from reading to writing, or vice versa) is performed at the index signal 9 at the end point. As a result, in order to read and write the test pattern for one round, one round, which is partially destroyed during the head state switching period, is not used. That is,
The pattern data for one round is written (or read) using the index signal 9 as the starting point, the magnetic head is switched after the index signal after one round, and the pattern data for one round (1
Rotation) takes a break from writing (or reading), waits for the next index signal 9, and starts from the next index signal 9 as the starting point.
Reading (or writing) is performed all around the entire circumference by rotation. However, if this is done, as shown in the figure, the waiting period T minutes is wasted, causing another problem that the time for defect inspection is doubled.

The present invention solves the problems of the prior art, and provides a magnetic disk medium that can efficiently and efficiently inspect defects on magnetic disk media continuously over the entire circumference of all tracks. The purpose of this invention is to provide a method for inspecting disk media for defects.

[Means for Solving the Problems] A feature of the present invention is that if a test pattern is written for one track revolution, the readout start point and readout end point match no matter where the test pattern is read out. For example, the test pattern for only one round can be read. Similarly, when writing a test pattern for one round, the focus is on the fact that no matter where on the track you start, as long as you return to the same position, you can write the test pattern for one round. Specifically, an index signal and its first part are used to ensure that the start and end points on the track are at the same position when reading or writing one round of the test pattern.
Using the same index signal that comes after the number of cycles, reading and writing of the test pattern for one cycle is performed. A plurality of such index signals are provided on one track, and the plurality of index signals are arranged at intervals equal to or longer than the head switching time. In this way, the writing and reading of test patterns can be performed sequentially starting from the next index signal after switching the head, without waiting for the waiting time of time T (see Figure 2b) after the index signal that is the end point. You can do it all the way through one round and continuously.

Therefore, the defect inspection method of the present invention for achieving the above object receives a regular index signal of each track obtained by detecting an index mark on a magnetic disk medium, and converts this index signal into a regular index signal. When generating a plurality of pseudo index signals, the time interval between a regular index signal and a pseudo index signal or the time interval between these pseudo index signals corresponds to the read/write head state switching. A pseudo index signal is generated in a state separated by a required time or more, and one of the regular index signal and the pseudo index signal is selected as the starting point and end point index signal, and the test pattern is written and the test pattern is read. The head state is switched according to the selected index signal generated after one rotation of the magnetic disk medium, and either the regular index or pseudo index signal following the selected index signal is performed. Either writing of test patterns or reading of test patterns is performed according to the index signal.

[Operation] In this way, in addition to the regular index signal obtained from the index mark, a pseudo index signal is generated according to this regular index signal, and the number of index signals that appear every round is increased to a plurality of numbers. A test pattern is written with the pseudo index signal or the above-mentioned regular index signal as the starting point and end point, or the written test pattern is read out, and for reading or writing the next test pattern, an index signal that appears one cycle later is used. Since the pseudo index signal or the regular index signal that appears after the head switching time is used as the index signal for the next starting point and ending point without any trouble, the sequential writing/reading of test patterns can be performed continuously throughout one cycle. It can be carried out.

Moreover, since the interval between the pseudo index signals and between the pseudo index and the regular index signal is longer than the time required for switching the head, even if the head is switched in response to any of these index signals, the switching will be performed reliably. I can do it. As a result, it is possible to efficiently inspect the magnetic disk medium for defects without creating a time gap for one round.

[Example] Hereinafter, an example of the present invention will be described in detail.

FIG. 1 is a block diagram of a defect inspection device equipped with a processing program for executing a defect inspection method for a magnetic disk medium according to an embodiment of the present invention, and its hardware configuration is shown in FIG. It is the same as the conventional one shown. The only difference is that the inspection processing program 22a installed in the memory 22 has been replaced with an inspection processing program 22b. The inspection processing program 22b internally generates a pseudo index signal 15 in response to the index signal 9, and internally generates a head switching control signal for the head switching control circuit 4, an activation signal for the write pattern generation circuit 7, etc. The control over the external circuit is the same as the conventional one except for the point that it responds to the pseudo index signal to be selected.

In this embodiment, the pseudo index signal 15
As will be described later, a plurality of times, for example, 30 or more times, are set at intervals of 14 required head switching times. For this purpose, the inspection processing program 2b receives the original index signal 9, counts the head state switching time in units of 14 in response to the original index signal 9, and generates the desired pseudo index signal 15. One of the plurality of generated pseudo index signals 15 is the regular index signal 9.
This can be easily identified by specifying the number since receiving the message.

Although the control operation of the head switching control circuit 4 shown in FIG. 1 is somewhat more complicated than the conventional one, the control program itself for performing the above operation can be created very easily. Further, the time count for the head switching time 14 is, for example,
It is sufficient to activate a hard timer or a soft timer to perform timer processing, and select a signal with a necessary timing as the pseudo index signal 15 from among the signals obtained by this timer processing.

FIG. 3 is a timing chart of processing performed by the inspection processing program 22b according to a method for inspecting defects on magnetic disk media. In the figure, reference numeral 14 indicates a time required for switching the head state which is longer than the time required for switching the head state 10, and reference numeral 15 indicates a pseudo index signal according to the present invention. Other symbols are the same as in FIG. 2.

Now, as explained in the prior art shown in FIG. 2b, in defect inspection of the magnetic disk medium 1,
The index signal 9 is used as the starting point and ending point. Put the magnetic head 2 into a writing state or a reading state,
Starting from the index signal 9 and ending with the index signal 9 one cycle later, test patterns are written or read out over the entire cycle. Then, the process ends at index signal 9 after one round. This point is the third
The same applies to the case shown in the figure, and the test pattern is written or read using the index signal 9 or the pseudo index signal 15 as the starting point and the same signal one cycle later as the ending point (write state (WR) 11 in Fig. 3, (See read state 12 (RD)). The difference between the conventional system and the present invention is that after head switching, the next operation can be started without waiting until the arrival of the next regular index signal 9.

First, using the index signal 9 in FIG. 3 as a reference, for example, test pattern data for one round is written thoroughly (writing state 11). This writing ends at the position where the index signal 9 is generated after writing for one cycle as in the conventional case. As explained above, in the conventional case, head switching is completed, but since the pseudo index signal 15 is not generated, the read operation after writing must be started after the regular index signal 9 arrives. If you do this, you will be able to
The rotation will be a rest.

However, in the present invention, this pseudo index signal 15 is provided between the first index signal 9 and the index signal 9 that appears one cycle later. Therefore, as shown in FIG. 3, the pseudo index signal 15 comes before the regular index signal 9 comes. Furthermore, there is a gap of 14 minutes between the index signal 9 and the next pseudo index signal 15. The required time 14 is set aside to be longer than the time required to switch the head state. this is,
This time is longer than the conventional required time of 10. Therefore, head switching can be performed reliably between these indexes. Therefore, the state of the magnetic head 2 is switched from writing to reading (or vice versa) in this required time 14 without stopping one revolution, and the next pseudo index signal 15 is generated.
can be used as index signals for the next starting point and ending point to continue processing. This allows the next read operation (or write operation) to proceed. Since the same pseudo index signal 15 that comes one cycle after the pseudo index signal 15 adopted as the starting point becomes the end point, the read operation (or write operation) at this time can be performed throughout one cycle.

In this case, if the interval between the index signal 9 and the pseudo index signal 15 becomes shorter than the conventional head switching time 10, an unread area ( Otherwise, an unwritten area) may occur. Although not shown in the drawings, the switching of the head state during defect inspection involves the transition from writing to reading as described above, and
There are cases where there is a transition from reading to writing.

The above describes only the relationship between the index signal 9 and one pseudo index signal 15, but as explained earlier, a plurality of pseudo index signals 15 may be provided, so the relationship between the index signal 9 and one pseudo index signal 15 is explained. The relationship with the index signal 15 is the same among a plurality of pseudo index signals 15. These are each set apart by head state switching duration 14. It is more efficient to provide a plurality of such pseudo index signals 15 at intervals of the head switching time 14, and generally, for example, 30 pseudo index signals 15 are provided at intervals of the predetermined time 14 for one track. It is better to set the above.

In this way, a plurality of pseudo index signals 15
is longer than the head state switching time 1
4, after reading or writing data for one cycle, the data will be output between multiple pseudo index signals 15 or pseudo index signal 1.
5 and index signal 9, the state of the head can be continuously switched from read to write or from write to read. Between these, the relationship between the index signal 9 and the index signal 15 shown in FIG. 3 is repeated as is, so that one track round's worth of scanning is performed at the index signals selected as the respective start and end points. , Continuous inspection processing can be performed without generating unread areas or unwritten areas as in the conventional method.

[Effects of the Invention] As explained above, according to the present invention, in addition to the normal index signal, a pseudo index signal is provided by ensuring a head switching period, so that by using this pseudo index signal, the magnetic disk medium can be This has the effect that defect inspection can be carried out almost continuously over the entire circumference of the entire track.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a defect inspection device equipped with a processing program for executing a defect inspection method for magnetic disk media according to an embodiment of the present invention;
2 is a timing chart of test pattern writing/reading processing in conventional defect detection; FIG. 3 is a timing chart of processing according to the magnetic disk medium defect inspection method of the defect inspection apparatus shown in FIG. 1; The figure is a block diagram of a conventional defect inspection method. 1...Magnetic disk, 2...Magnetic head, 3...
...Head IC, 4...Head switching control circuit (HCNTRL), 5...Write amplifier (WRA), 6
... Read circuit (RDA), 7 ... Write pattern generation circuit (WRPG), 8 ... Defect detection circuit (RDDET), 9 ... Index signal, 10, 1
4... Head switching time required, 15... Pseudo index signal, 20... Control circuit, 21... Microprocessor, 22... Memory, 22a, 22
b...Inspection processing program.

Claims (1)

[Claims] 1. Receive a regular index signal of each track obtained by detecting an index mark on a magnetic disk medium, generate a pseudo index signal according to this index signal, and combine the regular index signal and the pseudo index signal. or when a plurality of the pseudo index signals are generated, the pseudo index signals are generated with the time intervals between the pseudo index signals separated by at least the time required for switching the read/write head state. , one of the regular index signal and the pseudo index signal is selected as a starting point and an end point index signal to write a test pattern or read a test pattern, and the magnetic disk medium rotates until the first index signal is read. The head state is switched according to the selected index signal generated after the cycle, and the test pattern is written and the head state is changed according to the index signal of either the regular index or the pseudo index signal following the selected index signal. 1. A method for inspecting defects in a magnetic disk medium, comprising the step of reading the test pattern.