JP2674242B2 - Defect inspection method for recording medium of disk storage device - Google Patents

Description

The present invention relates to a method for inspecting a recording medium for defects in a disk storage device such as a fixed disk device.

[Conventional technology]

As is well known, the disk surface of a disk storage device
A magnetic thin film such as ferrite or chrome is applied as a recording medium by plating or vapor deposition. However, since the occurrence of defects due to microscopic non-uniformity of the thin film and contact scratches with external objects is unavoidable, In addition to eliminating defective products by precise surface inspection etc. with the disc alone, it is common to inspect defective parts in the surface after assembling in the device and then exclude it and perform formatting. is there.

Conventionally, dedicated inspection equipment has been used for defect inspection after being incorporated in this device.From now on, a write signal with a frequency as high as possible is given to the device to write it on the disk surface and then put it through the head of the device. Then, the analog value of the read signal is evaluated, and the part where the analog value does not reach the specified level is registered as a defective part. Further, after erasing the written contents, the contents are read again, and a portion where the analog value of the read signal is higher than a prescribed level is also registered as a defective portion.

[Problems to be solved by the invention]

The defect inspection method using the above-mentioned exclusive inspection equipment has an advantage that the control level for the defect can be arbitrarily set by selecting the detection level because the defect is detected in an analog manner from the read signal, and it is detected by selecting the frequency of the write signal. You can also specify the size of the defect to be made, but since the inspection takes time and the number of disk storage devices that can be inspected by one unit is limited, the equipment cost is expensive and the inspection takes a lot of time and mass production is too much. There is a problem that is not suitable.

Another problem of the conventional defect inspection method is that the detection accuracy can be sufficiently increased, but it is not necessarily a measure for determining whether or not the defect is acceptable for the disk storage device based on the inspection result. That is, whether or not a certain defect can be tolerated depends not only on the degree of the defect, but also on the modulation method in the data recording of the disk storage device, the format of the formatting including the synchronization data, the performance of the signal processing system of the read signal, the head operation This is because it also depends on factors such as the positioning accuracy of the system.

Also, due to recent technological advances, the number of disk defects, especially the number of heavy defects, has become smaller than in the past, and the number of light defects whose acceptability is rather determined by the overall performance of the disk storage device has become almost the same. In that case, the inspection standard may be too strict or, on the contrary, too sweet.

An object of the present invention is to solve the problems of the conventional method, and to obtain a defect inspection method for a recording medium, which is suitable for mass production with almost no trouble and is capable of practically determining acceptability of defects.

[Means for solving the problem]

The object of the present invention is to perform a formatting step of writing formatting data to each track in the disc to set a data sector, and a first inspection step of reading the formatting data and inspecting each sector for a defect. This is achieved by inspecting the recording medium for defects through a second inspection step of writing inspection data in each sector determined to be defect-free and reading it to inspect whether there is a defect in each sector.

[Action]

The method for inspecting a recording medium defect of a disk storage device according to the present invention inspects the recording medium by the disk storage device itself without using dedicated inspection equipment, and detects defects in units of data storage sectors. Is a feature.

Therefore, in the above-mentioned formatting step, the formatting data actually used for data recording of the disk storage device is written to each track in the disk and over the whole, and of course the head at that time is the device itself. Position with the head operation system.

In the next first inspection step, the formatting data is read and the presence or absence of a defect is inspected for each sector depending on whether or not it is correctly read. Of course, the positioning of the head at this time is performed by the apparatus itself.
By using a circuit incorporated in the apparatus itself for signal processing of a read signal and detection of a read error, the defect inspection is performed in the most practical form.

In the second inspection step, the inspection data is written in each sector which is determined to be defect-free in the first inspection step, and it is read whether or not it is correctly read, but the formatting data is not read for each sector. The device itself is also inspected for defects in the unwritten areas. It should be noted that the inspection data at this time is the data itself that is originally written in each sector, but it is possible to appropriately select several types of data that are convenient in detecting defects, that is, in which write errors and read errors are likely to occur.

As described above, in the method of the present invention, the defect inspection for each sector can be performed by the apparatus itself without using special equipment and in the most practical form while taking the above-mentioned three steps. Is solved.

It should be noted that the defective sectors detected in the first and second inspection steps are left as registration in the disk surface, and if there are defective sectors, reformatting that excludes them is appropriately performed.

〔Example〕

Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a disk storage device showing a part related to implementation of the method of the present invention, and FIG. 2 is a flow chart illustrating an operation including three steps according to the method of the present invention.

The disk storage device 30 shown in FIG. 1 is a fixed disk device, and in this example, the mechanical unit 10 and the controller unit 20.
Consists of Servo information SI for detecting the position of the head is written in each fan-shaped area on each surface of the disk 11 which is usually provided in the mechanical section 10 in several hundreds of lines on the basis of this servo information. Track T is set, and in this embodiment, a defective sector as an inspection result is recorded or registered in the outermost diameter track To thereof. The head 12 provided for each disk surface is supported by a carriage 13 which is movable in the left-right direction via a thin leaf spring as usual, and a head operating motor 14 coupled thereto is driven by a drive circuit 15 to drive the head operating motor 14. Its position is manipulated.

In addition to the above, a read / write circuit 16 connected to the head 12 as usual, a demodulation circuit 17 for a read signal RS from its read output R, and a track from the analog read signal RS to each track of the head. An off-track detection circuit 18 for detecting the off-track amount for Furthermore, a processor 19 is incorporated for overall control within the mechanical section, and the drive circuit
The drive command is issued to 15, the head selection command and the read / write command are issued to the read / write circuit 16, and the off-track amount is received from the off-track detection circuit 18.

The signal processing circuit 21 in the controller unit 20 reads the read signal RS.
And write signal WS encoder / decoder circuit and read signal
RLL in read / write circuit 16 including sync separation circuit for RS
A write signal WS of a modulation method or the like is given, and a read signal RS of the same modulation method is received from the demodulation circuit 17. The data control circuit 22 is a so-called data processor for exchanging serial signals and parallel data exchanged with the signal processing circuit 21, and has a RAM 22a for temporarily storing, for example, one track of write data or read data therein. Hold.

In addition, a processor 23 is mainly incorporated in the controller unit 20 for the purpose of linking with a computer, and in addition to linking with a computer (not shown) via an internal bus 24, an interface 25 and an external bus 26, a signal processing circuit The operation of 21 is controlled via a signal line, and the operation of the data control circuit 22 is controlled via a communication bus 27. Further, the processor 23 is also interconnected with the above-mentioned processor 19 in the mechanical section 10 via some signal lines, the interface 28 and the interconnection bus 29. The internal bus 24 is also connected to the RAM 22a of the data control circuit 22 for passing write data and read data to and from the computer.

Now, the formatting step which constitutes the present invention
S20, first inspection step S30 and second inspection step S
40 is a processor 23 of the controller unit 20 in this embodiment.
Of course, they may be incorporated in the processor 19 of the mechanical unit 10, and in a so-called controller-type disk storage device, they are incorporated in a common processor.

FIG. 2 is a flow chart showing the operation of this software, in which the operations of the above-mentioned three steps S20 to S40 are each surrounded by a dashed line. In this embodiment, the second
Detection step S40 of writing inspection data in step S40
Only 41 is incorporated in the flow of the operation by the first inspection step S30 for convenience.

In the first step S1 of the illustrated flow, 1 is set to the flow control flag F to specify that the inspection operation is being performed, and then the process proceeds to a single step S21 as the formatting step S20. In this step S21, the head 2 is usually the outermost track in the disk 1 which is the 0th track.
It is sequentially placed on each track T starting from To, formatting data is written in the entire track including a so-called gap in normal formatting of that track, and several tens of sectors are set in each track T. This formatting data includes a collating unit such as a sector number and synchronization data used at the time of reading.

Note that the positioning of the head 12 on each track T is handled by the processor 19 of the mechanical unit 10, and the off-track amount detected by reading the servo information SI is received from the off-track detection circuit 18 and set to 0. A drive command is given to the drive circuit 15 of the operation motor 14 to perform closed loop control of the position of the head. The formatting data is given from the processor 23 of the controller unit 20 to the data control circuit 22, and stored in the RAM 22a for one track, for example, and then a write signal is given.
Send to the read / write circuit 16 in the form of WS.

Steps S2 to S9 are preparatory steps for the first and second inspection steps. In step S2, it is determined whether or not the flag F is 0. Now, since 1 is set in this flag, the process moves to step S3, 0 is put in the variable i representing the number of inspections, and only 1 is set in the next step S4. Step forward and specify the first inspection. In steps S5 and S6, the flow is divided according to the value of the variable i, but since the value is 1 now, the operation proceeds to step S7 and the highest frequency data DH is designated as the inspection data TD.

Then, the operation enters the first inspection step S30, and in the first step S31, 0 is put in the track number variable j to specify that the inspection is started from the outermost diameter track To. In step S32, a so-called seek operation of moving the head 2 to the track Tj of the track number j is performed, and the head is positioned at the regular position of this track by the above-mentioned closed loop control referring to the servo information SI.

The next step S33 is a step for reading the formatting data FDj previously written in the track Tj in the formatting step S20, and a step for detecting a defective sector depending on whether or not it has been correctly read, from the processor 23 of the controller unit 20. In response to the command, the data control circuit 22 reads one track of the formatting data FDj from the read / write circuit 16, demodulation circuit 17 and signal processing circuit 2
The data is read via 1 and temporarily stored in the RAM 22a, then the contents are inspected for each sector, and the presence or absence of a read error and, if there is an error, the defective sector number is processed by the processor.
Report to 23.

As can be seen from this, in the method of the present invention, the presence or absence of a defect in each sector is inspected in a practical form including the operation characteristics or performance of the demodulation circuit 17 and the signal processing circuit 21. Further, the formatting data written in the formatting step 20 indicates the head position in step S32 in this embodiment.
Since the data is read after being replaced with, the inspection is performed in the most practical form that further includes the accuracy of the head positioning system.

In the following step S34, the flow is changed depending on whether or not an error is detected as a result of the inspection in step S33. If there is no error, the operation proceeds to step S35 and it is determined whether or not the flag F is 0. However, since the flag F is now 1, the operation is further performed in step S40 as the second detection step S40 in this example.
Move to 40. If there is an error, the operation proceeds to step S36, but since the flag F is 1, the operation proceeds to step S37, and the defective sector detected in step S33 is detected by the processor 2, for example.
Remember in 3. The operation after this is the same as the above step S41.
Moved to

In the step S41 in this embodiment, the inspection data TD is written and placed by using the flow of the first inspection step S30, and the head is repositioned in the second inspection step S40 and then read. It is inserted to do. In this step S41, this inspection data TD is written in the sector which is determined to be defect-free according to the inspection result of step S33. The inspection data TD is written via the data control circuit 22, the signal processing circuit 21, and the read / write circuit 16 as in the above.

The next step S38 is a step in the first inspection step S30, in which it is determined whether or not the track number variable j has reached the maximum value jm, and if not, the variable j is incremented in step S39 before the flow. Return to step S32 and repeat the same operation.
When the operation of the first inspection step S30 for all tracks T on the disk 1 is finished and the variable j reaches the maximum value jm,
The flow exits the operation loop from step S38 and moves to step S10. Since the flag F is 1, the flow further enters step S42 in the second inspection step 40.

In this step S42, the track number variable j is returned to 0, and in the next step S43, the head is sought to the j-th track Tj and positioned at its normal position as before. Inspection data written in step S41 before step S44
This is the step of reading and inspecting the TD, and the previous step S3
The data control circuit 22 reads and inspects this inspection data TD in the same manner as 3 and reports the result to the processor 23.
The defect inspection in the second inspection step 40 is the demodulation circuit 1
As in the first inspection step 30, the performance and accuracy of the signal processing circuit 21, the head positioning system, etc. are included.

In a succeeding step S45, it is determined whether or not there is an error, and only when there is an error, the defective sector is stored in step S46. In step S47, the variable j is compared with its maximum value jm,
As long as it is smaller than that, the variable j is incremented in step S48, the flow is returned to step S43, and the same operation is repeated.
After the operation of the second inspection step 40 for all the tracks is completed, the flow moves to step S11.

In this embodiment, since the inspection data TD is changed and the inspection is repeated im times, for example, five times, the variable i is compared with the maximum value im in step S11, and the flow is returned to step S4 unless it is reached. Step the variable i. Although the inspection data TD for the first inspection in which the value of the variable i is 1 is the highest frequency data DH which repeats 492 in the RLL modulation method, for example, after the variable i advances to 2 in step S4. In the step S8 via the steps S5 and S6, the lowest frequency data DL, which is 33 repetitions, is designated by the same modulation method as the second inspection data TD. In this embodiment, after completion of the inspection using the highest and lowest frequency data, random data DR of one sector length randomly specified in the inspection data TD from the third time onward is designated in step S9.

The operation of the first and second inspection steps S30 and S40 after the inspection data TD is switched in this way is the same as that described above, and step S3 is performed each time a defective sector is newly detected.
The defective sector number is added to the stored contents of 7 and S46.

After the inspection is performed a predetermined number of times, the operation shifts from step S11 to step S12, the flag F is set to 0, the flow returns to the formatting step S20, and the formatting data is rewritten to make the disk storage device usable. Of course, in such reformatting, the defective sectors stored in steps S37 and S46 are skipped and formatting is performed. The number of defective sectors in one disk surface is at most 10, and the probability of multiple defective sectors occurring in one track is very low. The entire area of each track, including the gap, is normally inspected. Therefore, this reformatting is almost certainly possible.

After the reformatting is completed, the operation goes to step S2, and the flag F is set to 0 this time, so that the flow moves to step S60, and the defective sector detected in the first and second inspection steps S30 and S40, for example, the track number. In this embodiment, which has already been reformatted, the sector number and the sector number are registered in the outermost diameter track To.

Further, in this embodiment, since the confirmation inspection of reformatting is performed by using the first inspection step S30,
Therefore, in the subsequent step S13, 1 is put into the variable j, and in this example, the confirmation inspection is started from the track next to the outermost diameter track To, and then the flow is entered into step 32.

During the operation of the first inspection step S30 at the time of this confirmation inspection,
As a result of the read inspection of the formatting data FDj in step S33, the operation when there is no error enters from step S34 to step S35, and since the flag F is 0, the operation is entered into step S38 without passing through step S41. However, in the case of an error, the operation proceeds from step S34 to step S36, and in this embodiment, as shown by the broken line in the figure, for example, the fact that the reformatting is defective is displayed and then the flow is immediately terminated or interrupted. If reformatting is confirmed to be good for all tracks, the operation moves from step S38 to step S10, and since the flag F is 0 this time, the entire flow is completed.

It is desirable that the inspection data TD used in the second inspection step S40 in the above operation include an error check code or an error correction code like normal data. However, the error correction function by this is performed. The data control circuit 22 is designated by the processor 23 so as not to exist.

The time required for the second total operation in the above-described embodiment is usually about one hour, which is about three times as long as when the conventional dedicated inspection equipment is used, but the method of the present invention uses the disk storage device 30 itself shown in FIG. Since this sequence of operations can be automatically performed in parallel for any number of units, inspection work is hardly required, and great convenience can be obtained in mass production of disk storage devices.

The present invention is not limited to the embodiments described above, and can be implemented in various modes. The specific configuration of the disk storage device as an implementation target of the present invention in FIG. 1 and the operation contents and the order of steps of the method of the present invention in FIG. It is possible to add appropriate changes and substitutions to the contents of the operation.

For example, in the embodiment, the erase inspection function of the recorded contents by the conventional dedicated inspection equipment is not provided, but step S11 in FIG.
Instead of returning the flow from step S4 to step S4, if the flow is returned to the formatting step S20 after passing through the operation step for erase, the method of the present invention can have a function equivalent to the conventional erase inspection. .

〔The invention's effect〕

As described above, in the method of the present invention, the formatting step of writing the formatting data to the whole of each track set on the disk surface to set the sector for data storage, and reading the formatting data to inspect the presence or absence of a defect for each sector. Recording is performed via a first inspection step for performing inspection, and a second inspection step for writing inspection data into each sector determined to be defect-free in the first inspection step and reading the sector to inspect whether there is a defect in each sector. The following effects can be obtained by inspecting the medium for defects.

(A) Since the formatting data is inspected on a sector-by-sector basis in the first inspection step, it is possible to write and read the inspection data, which is convenient for detecting a defect, to a sector which has no defect. it can.
Therefore, fine defects can also be detected by writing and reading suitable inspection data for the sector and inspecting it in the second inspection step. Therefore, the recording medium of the disc can be automatically inspected by the disc storage device itself without using dedicated inspection equipment.

(B) The recording medium can be inspected according to the most practical standard including the performance and accuracy of the signal processing circuit of the read signal of the disk storage device, the positioning system of the head, etc., and therefore the standard is too strict or, conversely, too sweet. There is no irrationality like inspecting.

(C) All defects of the recording medium are inspected in units of data sectors, so that simple software can be loaded into the disk storage device, and the present invention can be easily performed without adding or changing the configuration. The method can be carried out.

The present invention is not very suitable for obtaining information for managing process conditions of a recording medium such as detection of minute defects and grasp of defect distribution as in the case of using a dedicated inspection facility, but it is efficient in mass production of disk storage devices. Therefore, it is possible to provide a highly practical method of inspecting a recording medium, which is capable of inspecting defects in accordance with rational quality control standards.

[Brief description of the drawings]

The drawings are all related to the present invention. FIG. 1 is a block diagram showing the essential part of a disk storage device which is an object of the defect inspection method for a recording medium according to the present invention, and FIG. 2 is software for the method according to the present invention. 10 is a flow chart of operational steps exemplified in terms of aspects. In the figure, 10: mechanism of disk storage device, 11: disk, 12: head, 13: carriage, 14: head operating motor, 15: head operating motor drive circuit, 16: read / write circuit, 17: demodulation circuit, 18: Off-track detection circuit, 19: Processor, 20:
Controller unit of disk storage device, 21: signal processing circuit, 22: data control circuit, 22a: RAM, 23: processor, 24:
Internal bus, 25: Interface, 26: External bus, 27: Communication bus, 28: Interface, 29: Interconnected bus, 30: Disk storage device, DH: Maximum frequency data as inspection data, D
L: lowest frequency data as inspection data, DR: random data as inspection data, F: flag, FD: formatting data, i: variable representing the number of inspections, im: maximum value for variable i, j: track number variable, jm: maximum value for variable j, RS: read signal, SI: servo information, S1 to S13: related operation step of the method of the present invention, S20: formatting step, S21: operation step during formatting step, S30: first inspection Step, S31 to S39: operation step in the first inspection step, S40: second inspection step,
S41 to S48: operation step in the second inspection step, T: track, TD: inspection data, To: outermost diameter track, WS: write signal.

Claims (1)

(57) [Claims] 1. A formatting step of writing formatting data to the whole of each track set on a disk surface to set a sector for data storage, and a first reading of the formatting data to inspect each sector for a defect. And the second inspection step of writing inspection data into each sector determined to be defect-free in the first inspection step and reading the inspection data to inspect whether there is a defect in each sector. Two
The method for inspecting a defect of a recording medium of a disk recording device, wherein a sector in which a defect is detected in the inspection step is registered in the disk.