JP2001184636A - Method for predicting generation of abnormality in master by transfer media measurement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow the prediction of the generation of abnormality in master media formed to be a master disk of transfer media. SOLUTION: The average amplitude value of transfer signals not enough to the prescribed value when measuring the signal of the transfer media transferred from the same master is defined as TAA error, and the number of generating times of the TAA error is counted and stored (refer to step S8) for every address of the transfer media, the master of which is common, then the number of generating times of the TAA error on the same address, e.g. the number of those of N1 or more is checked (refer to step S9), and the generation of abnormality in the master is predicted from this number (refer to steps S10, 11).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating an information recording medium such as a hard disk, and more particularly to a method for predicting the occurrence of an abnormality in a master medium (hereinafter simply referred to as a master) of a magnetic recording medium which performs recording by magnetic transfer. About.

[0002]

2. Description of the Related Art A magnetic disk drive device in which a disk-shaped disk is used as a recording medium and information is read or written by a flying head while rotating the disk at high speed has been put to practical use as an external storage device of a computer. This magnetic disk drive device is based on a device in which tracks are arranged concentrically at regular intervals on the surface of a disk-shaped magnetic disk so that digital information can be recorded and reproduced therefrom. Further, a method is generally used in which control information such as a track address and position information is previously written in a portion called a wedge arranged at regular intervals on a track. The process of writing this control information is called a normal preformat. Conventionally, preformatting is generally performed by a servo track writer.

[0003] In recent years, as the capacity of magnetic disks has increased, the demand for narrower track pitches has increased. In the future, when the track pitch becomes 1 μm or less, it is predicted that preformatting will be difficult due to the limit of the positional accuracy of the servo track writer. Further, there is a concern that preformatting may take an enormous amount of time due to an increase in the number of tracks. As a solution, a preformat by magnetic transfer has been developed. In this method, servo information called a reference servo pattern is directly transferred from a master disk to a magnetic disk.

FIG. 7 shows a recording format of a reference servo pattern. In the figure, the wedge is a portion where a magnetization pattern is recorded, and there are about 200 wedges at equal intervals on the circumference. Synchronization information, address information and servo information are embedded in each wedge, and one reference wedge is determined by the address information. In the process of manufacturing a magnetic disk by such a method, the reference servo pattern finally transferred is checked.
This check is based on measuring the read signal of the recording area while rotating the medium, and judging the quality of the transfer signal based on the result. The position at which the signal is measured is set for each wedge on a virtual track that is spaced at a fixed interval.

FIG. 8A shows a read signal of the reference servo pattern, and FIG. 8B shows an enlarged waveform of the wedge portion. In the measurement, with respect to the pulse signal of each wedge shown in FIG. 8B, the characteristic value (for example, average amplitude, period, jitter, etc.) of the waveform is obtained. Incidentally, such a measuring operation can now be performed almost automatically by computer control.

[0006] By the way, a strict inspection is also performed at the time of manufacture of a master medium as a master, and only a master that passes the inspection is used for transfer. However, an error may occur in the master while the transfer is being repeated, resulting in a transfer failure. As a cause thereof, for example, there is adhesion of particles (dust and the like) and generation of scratches. A transfer failure due to such an abnormality usually appears as a decrease in a reproduction signal of the transfer medium. For this reason, the master performs a re-inspection every fixed number of times of transfer or a cycle, and performs re-cleaning and the like as necessary.

[0007]

As described above, since the period for re-inspection of the master is fixed in the related art, even if a serious abnormality occurs in the master, the re-inspection period is reached or the non-defective rate Unless the occurrence of an abnormality is clarified due to a significant decrease in the size of the device, the device is used as it is. For this reason, a large percentage of media that fail in the evaluation process are caused by master abnormalities, which has been a factor that lowers the non-defective product rate.
Therefore, an object of the present invention is to provide a method for making it possible to predict occurrence of a master abnormality.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a signal of a transfer medium preformatted by magnetic transfer processing from a master is measured, and a transfer signal at the time of the signal measurement is measured. When the error whose average amplitude value is less than a predetermined value is regarded as an error, the number of error occurrences is counted and stored for each address of the transfer medium sharing the master, and the number of error occurrences at the same address is a fixed number. It is characterized in that the number of the above items is checked, and occurrence of a master abnormality is predicted based on the number. According to the first aspect of the present invention, it is possible to determine the level of the master abnormality and issue an alarm according to the level (the second aspect of the invention).

[0009]

FIG. 1 is a flowchart showing an embodiment of the present invention, and FIG. 2 is a system configuration diagram to which the present invention is applied. First, FIG. 2 will be described. The transfer medium 14 in FIG. 2 is a medium to be evaluated and is a medium magnetically transferred from a master (not shown). The spindle motor 13 includes a motor and a rotating shaft, and rotates the transfer medium 14 fixed to the rotating shaft at a high speed. Head 15
Performs magnetic recording and reproduction, and is composed of a magnetoresistive element and a head slider for fixing the element. The head 15 moves in conjunction with the positioner 12, and is positioned by this. The read signal a is a signal obtained by amplifying the reproduction signal of the head 15 by the head amplifier 11.

The signal analyzer 2 receives a read signal a,
The measurement is performed. An A / D 8 is an A / D converter for digitizing an analog signal by sampling and quantizing an input signal, a waveform memory 9 is a memory for temporarily storing the digital data, and an analyzing unit 10 is a digital memory for the waveform memory 9. The data is analyzed to measure the average amplitude and period of the pulse waveform. The measurement data b is stored in the analysis unit 10
Is transmitted to the computer unit 1 by communication.

The computer unit 1 issues a control command to each unit in the system based on the installed program, and controls them. For example, it issues start / stop commands to the spindle motor 13 and control commands such as sampling of the read signal a, execution of measurement, and request for measurement data to the signal analyzer 2. Reference numeral 16 denotes a program in which a series of evaluation procedures is described. The program is stored in the external storage device 7 as shown in the figure, and is loaded into the memory 6 at the time of execution, and is decoded and executed by the CPU 5. The computer unit 1 is further connected with a keyboard 3 and a display device 4 as input / output devices.

Next, various data used in the present invention will be described. First, a master management table T1 is used to manage information of a master medium. FIG. 3 shows an example of the format. The master number is the identification (I) of the master (master) of the transfer medium evaluated in the past by this evaluation system.
D) The number and the last inspection date and time indicate the date and time when the master was last inspected when the media was evaluated. This table T1 is stored as a disk file in the external storage device 7 of the computer unit 1 in FIG. 2, for example.

FIG. 4 is an explanatory diagram of a TAA error management table. In FIG. Is a number assigned to the circumference where the measurement area is set, and the outermost track is 0. Wedge No. Is a number assigned to each wedge on the same circumference, and the reference wedge is 0.
And increment the number by one in the order of the rotation direction of the medium. The number of occurrences of the TAA error is obtained by accumulating the number of occurrences of a situation where the average amplitude value is less than a predetermined value (this is usually called a TAA error) in the signal measurement of the medium transferred from the master. This table T2
Is newly created as a table corresponding to the new master when the new master is registered in the master management table. Then, like the master management table, it is stored as a disk file in the external storage device 7 of the computer unit 1 in FIG.

In order to store the correspondence information between the transfer medium and the master, a master correspondence list is used here. An example is shown in FIG. The master correspondence list L is created by recording on a paper or the like by a worker in the transfer process, and is passed to the evaluation process together with a series of media to be evaluated. The transfer media number in FIG. 5 is an ID number assigned to the transfer medium, the master number is the number of the master of the transfer medium, and the last inspection date and time indicates the date and time when the master was last inspected at the time of transfer.

Here, referring to FIGS. 1 and 2, a description will be given of a procedure for evaluating a transfer signal and predicting a master abnormality occurrence according to an embodiment of the present invention. First, it is assumed that the program 16 has already been started and is being executed as an initial condition. In the evaluation process, the operator evaluates new media,
The user operates the keyboard 3 to input an evaluation start command. Then, in step S1 of FIG. 1, a message prompting input of the media number of the media to be evaluated, the master number, and the final inspection date and time of the master is displayed.
5 is displayed on the display device 4 of FIG.
With reference to the master correspondence list L, these pieces of information are input.

Next, in step S2, the input master number is checked against the master management table T1 in FIG. 3 to check whether or not the master is registered. If registered, go to S3; if not registered, S
At 14, the master is registered in the master management table T1, and at S15, a TAA management table T2 corresponding to the master is newly created. In S3, the entered final inspection date and time are compared with those in the master management table T1, and it is checked whether the master has been inspected again.
If it is determined that the reexamination has not been performed, that is, if the examination date and time are the same, the process skips S4 and goes to S5. If new, go to S4.

In S4, the TAA management table T2 corresponding to the master is initialized, that is, the number of TAA errors is reset to 0, and the master management table T1 is further reset.
Is changed to the input date and time. In S5, a message prompting the user to set a medium to be evaluated is displayed on the display device 4. The operator sets the transfer medium 14 on the rotation axis of the spindle motor 13 and inputs a start command using the keyboard 3. . In the next S6, the signal of the set medium is measured. The computer section 1 issues a start command to the spindle motor 13 and sends a position command to the positioner 12 when the rotation of the spindle motor 13 reaches a steady state to load the head 15 on the outermost track. As a result, the head amplifier 11 outputs the read signal a of the track.

Next, the computer unit 1 includes a signal analysis unit 2
And a series of measurements (mean amplitude measurement, pulse period measurement, jitter measurement) are sequentially performed on the pulse waveform of each wedge on the track. Further, the measurement data b is requested from the signal analysis unit 2 and is sent to the memory 6
To be stored. When the measurement of the track is completed, a position command is sent to the positioner 12, the head 15 is moved in the inner circumferential direction by one track, and the same measurement as described above is performed.
When measurement of all tracks is completed in this way, head 1
5 is retracted to the home position, and a braking command is sent to the spindle motor 13. In S7, a message prompting the user to remove the medium is displayed on the display device 4, so that the operator removes the medium and inputs a command to shift to the next step from the keyboard 3.

When the signal measurement is completed, the measurement data of the transfer signal is stored in the memory 6 for each measurement item. For example, the measurement data of the average amplitude measurement is, as shown in FIG.
o. ) And the measured values are stored in association with each other. Hereinafter, the track No. And wedge No. Are called an address. S
At 7a, the quality of the transfer signal is determined based on the measurement data. Since the specific contents are not directly related to the present invention, the description is omitted. In the next S8, the T of the corresponding master is determined based on the average amplitude measurement data.
An update process of the AA management table is performed. That is,
The average amplitude value for each address is set to a certain threshold (V
Compared to 1), those less than this are judged as TAA errors, and TAA of the same address in the TAA management table T2.
Increment the error occurrence count. The determination is performed for all addresses, and the update process is completed.

In S9, the TAA management table T2 is searched to check how many TAA error occurrences are equal to or more than a certain value (N1). Here, N1 is set to a number of occurrences sufficient to predict that there is some abnormality near the address of the master of the transfer medium. In S10, the estimated number of abnormal addresses is set to a predetermined threshold value N2, N3 (N2 <N3).
And the level of the master abnormality is evaluated. Here, the respective values are set so that a value less than the threshold value N2 is regarded as an allowable level of abnormality of the master, and a value greater than or equal to N3 is regarded as a serious level of abnormality.

If the number of abnormal addresses is less than N2 in S10, the process goes to S13, and if it is more than N2 and less than N3, S1
In step 1, a message is displayed on the display device 4 warning that the time for re-testing the master is approaching. If it is equal to or more than N3, a message is displayed in S12 that warns that the use of the master is immediately stopped and a retest is performed. Next, in S13, a message for inquiring whether to end or continue the evaluation is displayed on the display device 4. Here, when the operator selects termination, a series of operations is terminated. If you are evaluating new media, select Continue. Then return to S1,
Thereafter, evaluation of a new medium is performed in the same procedure.

[0022]

According to the present invention, the following effects are expected. 1) Since the occurrence of an abnormality in the master is predicted, and whether or not to perform a retest is determined based on the result, it is unlikely that the master in which the abnormality has occurred is continuously used. 2) It is known that the correlation between the transfer failure when particles or the like adheres and the increase in the number of TAA errors occurring at the same position is very high. Since it is used as a prediction parameter, highly reliable prediction is possible. 3) When predicting the occurrence of an abnormality in the master, the level of the master abnormality is determined, and a predetermined warning (alarm) is issued according to the level.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a system to which the present invention is applied.

FIG. 3 is an explanatory diagram of a master management table.

FIG. 4 is an explanatory diagram of a TAA management table.

FIG. 5 is an explanatory diagram of a master correspondence list.

FIG. 6 is an explanatory diagram of average amplitude measurement data.

FIG. 7 is an explanatory diagram of a recording method of a reference servo pattern.

FIG. 8 shows a read signal of a reference servo pattern,
FIG. 4 is an explanatory diagram of an example of an enlarged signal waveform at a wedge portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Computer part, 2 ... Signal analysis device, 3 ... Keyboard, 4 ... Display device, 5 ... CPU, 6 ... Memory, 7 ... External storage device, 8 ... A / D (analog / digital converter), 9 ... Waveform Memory, 10 analysis unit, 11 head amplifier, 12 positioner, 13 spindle motor, 1
4: Transfer media, 15: Head, 16: Program,
T1: Master management table, T2: TAA (error) management table, L: Master correspondence list.

Claims (2)

[Claims] 1. A method for measuring a signal of a transfer medium preformatted by a magnetic transfer process from a master, and, when an error occurs when the average amplitude value of a transfer signal at the time of the signal measurement is less than a predetermined value, determines whether the master has an error. Count and store the number of error occurrences at each address for the common transfer media, check the number of errors with a certain number or more at the same address, and predict the occurrence of master failure based on that number A method for predicting the occurrence of a master abnormality by measuring a transfer medium. 2. A master abnormality level is determined.
2. The method according to claim 1, wherein an alarm is issued according to the level.