JP2000285401A - Servo writing method for magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an occurrence rate of faulty products by surely conducting performance checking of a servo writing magnetic head. SOLUTION: A test signal is written onto a magnetic recording medium 3 by means of a servo writing magnetic head 15 which writes a servo signal to be used for positioning the head. The test signal is then read out for conducting performance checking of the magnetic head 15. More specifically, a level checking in which a test signal of a predetermined frequency is written at every predetermined intervals of the magnetic recording medium 3 and then read out to check whether or not its output value V1 is equal to or larger than a specified value, a resolution checking in which several kinds of test signals with different frequencies are written and then read out to check whether or not a ratio V2/V3 (an output value V2 with a low frequency to an output value V3 with a high frequency) is equal to or larger than a specified value, and a modulation checking in which a test signal with a predetermined frequency is written and then read out to check whether or not a ratio V4/V5 (a maximum output value V4 to a minimum output value V5) is equal to or larger than a specified value, are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test signal written by a servo write magnetic head for recording a servo signal for accurately positioning a magnetic head of a floppy disk drive or a magnetic tape drive on a magnetic recording medium. The present invention relates to a servo write method for a magnetic recording medium for checking the performance of a servo write magnetic head by reading.

[0002]

2. Description of the Related Art Conventionally, a magnetic recording medium in which magnetic layers are formed on both sides of a disk-shaped base made of, for example, a flexible polyester sheet or the like and magnetic recording is performed on the magnetic layers by a magnetic head while rotating. A floppy disk housed in a case is provided, and is mainly used as a recording medium for a computer because of its advantages such as easy handling and low cost.

In such a floppy disk, the positioning of the magnetic head with respect to tracks formed concentrically on the magnetic recording medium is performed by open-loop control when the recording capacity is small, but the recording capacity is increased. Therefore, when the track density becomes a high track density of 150 to 200 TPI or more, it is necessary to perform the positioning of the magnetic head by the closed loop control, and it is required to write a servo signal before shipping the product. Also,
Similarly, writing of servo signals is required for magnetic tapes as the recording density increases.

[0004]

However, the servo write magnetic head for writing the above servo signal wears due to its use, and when the servo signal is written by the worn magnetic head, a decrease in output or the like occurs. No function is obtained, causing quality abnormalities. The progress of head wear of this magnetic head greatly varies depending on individual differences of the magnetic head, head mounting posture, head height, etc., and cannot be dealt with by replacing the magnetic head within a predetermined servo write time or a predetermined number of times of servo write. In addition, there is a possibility that a magnetic head that can be used is replaced or a servo head is written with a magnetic head whose performance has deteriorated to produce a defective product.

[0005] The above-mentioned decrease in output due to head wear does not occur in proportion to the progress of head wear, but has a characteristic that it deteriorates rapidly from a certain point in time. Therefore, for example, when the performance of the magnetic head is checked at the start of every day, there is a possibility that the performance is rapidly deteriorated in a short time after the check and a large number of defective products are produced.

In the conventional performance check of a magnetic head, a signal written on a magnetic recording medium is read out, displayed on an oscillograph, and judged based on an output value and the like. Increasing the cost causes a decrease in the operating rate and an increase in production costs due to an increase in labor costs. In addition, the performance check of the magnetic head is insufficient if the determination of whether the output value is equal to or greater than the specified value is likely to result in degradation of resolution or modulation in some cases.

In view of the above, the present invention has been made in view of the above circumstances, and provides a servo write method for a magnetic recording medium in which the performance of a servo write magnetic head is reliably checked to reduce the occurrence of defective products. It will not be provided.

[0008]

According to the present invention, there is provided a servo recording method for a magnetic recording medium, comprising: writing a test signal on a magnetic recording medium by using a servo write magnetic head for writing a servo signal for head positioning; The test signal is read to check the performance of the magnetic head for servo writing, and the performance check is performed by writing a test signal of a predetermined frequency at predetermined intervals of the magnetic recording medium and reading the test signal. The first check is to perform a level check that the output value is equal to or greater than a specified value, and the ratio of the high-frequency output value to the low-frequency output value when a plurality of types of test signals having different frequencies are written and read is read. A second check for performing a resolution check to determine that the The maximum value and the minimum value of the output value when the strike signal is written and read out are detected, and the determination is made based on a third check for performing a modulation check that a ratio of the minimum value to the maximum value is equal to or more than a specified value. It is characterized by the following.

Further, when it is determined that the apparatus is abnormal based on the result of the check, the equipment can be automatically stopped to prevent continuous production of defective products. Also,
It is preferable that a so-called maintenance call can be automatically transmitted by communication means or the like.

The performance check of the magnetic head for servo writing is performed at predetermined intervals and at predetermined intervals of the magnetic recording medium, and is performed at the time of servo writing to each magnetic recording medium. Is preferred.

In the case where the test signal is written in the user area (data area), if the signal remains in the guard band and the S / N ratio may be reduced when the user is using the test signal, the test signal may be checked every certain period. It is desirable that the magnetic recording medium used for this check is not a product.

Further, as signals used for checking the performance of the magnetic head for servo writing, signals used for signal processing in ordinary servo writing and media drive are used.
For the signal after the GC amplifier (automatic gain control amplifier), the above-described performance determination cannot be performed because the amplification process according to the magnitude of the read signal is performed. For this reason, the signals used for the first to third checks are read signals before the AGC amplifier or fixed magnification amplifiers other than the AGC amplifier are arranged before or in parallel with the AGC amplifier, and the check is performed using this signal. Do.

[0013]

As described above, according to the present invention, a predetermined test signal is written by the magnetic head for servo writing, read out, and the three checks of the level check, the resolution check and the modulation check are performed. Magnetic head deterioration can be determined, and this check can be performed by the servo write device.The check can be performed at high frequency without incurring a decrease in the operation rate and increase in production cost, and efficiently without producing defective products. The magnetic head suitable for the abrasion deterioration state can be replaced, and reliability can be secured.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 is a plan view showing an outline of a servo write device for carrying out the servo write method of the present invention.

The servo write apparatus 10 includes a mounting table 11 for receiving a floppy disk 1 in which a disk-shaped magnetic recording medium 3 is rotatably accommodated in a case 2 and a floppy disk 1 on the mounting table 11 (not shown). A holding table 12 held at a servo write position by a pull-in mechanism is provided. The shutter 4 of the floppy disk 1 held by the holding table 12 is opened to expose the magnetic recording medium 3 to a magnetic head insertion opening 5 opened.

Further, a spindle 13 for rotating and driving the magnetic recording medium 3 is provided at the center of the holding table 12, and a magnetic head 15 for servo writing is provided on the side. The spindle 13 chucks the hub 6 (center core) fixed at the upper end to the center of the magnetic recording medium 3 by magnetic attraction or the like. The spindle 13 is rotated at a high speed by a motor (not shown) to perform magnetic recording. The medium 3 is kept at a predetermined rotation.

The magnetic head 15 for servo write is vertically opposed to the tip of a suspension 16 with the magnetic recording medium 3 interposed therebetween, and is provided on a base 17 so as to reciprocate toward the center of the spindle 13. Is mounted on the linear guide 20 and is loaded at a predetermined position by a known loading mechanism 21. The load mechanism 21 detects the position of the magnetic head 15 for servo writing, and performs the positioning and drive the actuator (VCM current control).

Then, a servo signal for head positioning is written on the magnetic recording medium 3 by the magnetic head 15, a predetermined test signal is written on a predetermined track, and the test signal is read by a subsequent rotation. The performance of the magnetic head 15 is checked. The reading of the test signal may be performed by a test magnetic head (head gap) separately provided on the servo write magnetic head 15.

The performance check of the servo writer magnetic head 15 is determined from a first check for performing a level check, a second check for performing a resolution check, and a third check for performing a modulation check.

In the first level check, a test signal is written to a specified track at a predetermined frequency, and the test signal is read, for example, based on the upper and lower peak values (PP values) of the signal as shown in FIG. The output value V1 is detected,
This is performed when the output value V1 is equal to or greater than a specified value. In addition,
The output value may be a zero point and a peak value (0-P value). When the magnetic head 15 is worn, the output value V1 is reduced. When the output value V1 becomes lower than the specified value, it is determined that the magnetic head 15 cannot be used.

In the second resolution check, first, a test signal having a low frequency is written in a specified track, and the read signal is read, for example, from a P-signal as shown in FIG.
The output value V2 based on the P value (or 0-P value) is detected and stored. Next, a high-frequency test signal (approximately 3 to 5 times the previously written frequency) is written to the next track, and the read-out signal shown in FIG. Or 0-P value) and detects and stores the output value V3. Next, the ratio V2 / V3 of both output values is calculated,
If this is equal to or greater than a specified value, a resolution check is performed.
The output value V2 of the low frequency signal is the output value V of the high frequency signal.
3 and the ratio V2 /
When V3 is within the predetermined range, it can be determined that the resolution of the magnetic head 15 is sufficiently obtained.

In the third modulation check, a test signal of a specified frequency is written to a specified track, and an output value in the circumferential direction of a signal as shown in FIG. Value (or 0-P value)
Is detected when the ratio V4 / V5 of the minimum value V5 to the maximum value V4 is equal to or greater than a specified value. If the magnetic head 15 is distorted, an undulation occurs in the output signal, and the output signal fluctuates so as to decrease the ratio V4 / V5. Thus, it can be determined that the modulation of the magnetic head 15 is obtained.

The above-mentioned first to third checks are performed in principle at the time of servo writing to each magnetic recording medium 3, respectively. Further, it may be performed for every two or more predetermined number of the magnetic recording media 3, and is performed at a predetermined interval (timing and cycle).

The servo write magnetic head 15
When the test signal is written to the user area (data area) between the servo signals, the test signal is written over the entire track width. After that, when the test signal is erased by the data head, the signal is written to the guard band. Since there is a concern that the S / N ratio may decrease when the user remains in use, in this case, the first to the third is performed every two or more predetermined sheets.
A third check is performed, and it is desirable that the floppy disk 1 used for this check is not a product.

On the other hand, the servo write magnetic head 15
In a device having an erase head (erase gap) capable of erasing a signal over the entire track width, a test signal is written in a user area, and after the check, the test signal is erased by the erase head. Since the S / N ratio of the magnetic recording medium 3 does not decrease, a check may be performed on each magnetic recording medium 3 as a product. Further, the test signal may be written outside the user area.

The servo write magnetic head 15
As a signal used for the performance check, a read signal before the AGC amplifier or a fixed magnification amplifier other than the AGC amplifier is arranged before or in parallel with the AGC amplifier, and the signal is used.

The servo write magnetic head 15
Known techniques can be adopted for the structure of the signal source of the servo signal and the test signal to be transmitted to the CPU, the synchronous circuit, the read / write signal processing, and the like, and the description thereof will be omitted.

The servo writing by the servo writing device 10 described above is performed by the magnetic recording medium 3 on the spindle 13.
The servo write magnetic head 15 is loaded at a predetermined position on the magnetic recording medium 3 while the hub 6 is being suction-held and rotated at a predetermined rotation speed, and the predetermined servo is synchronized with a clock signal. The pattern is written, and the servo write magnetic head 15 is sequentially fed from the outer circumference to the inner circumference or from the inner circumference to the outer circumference of the magnetic recording medium 3 by the load mechanism 21 by a distance corresponding to a 1/2 track pitch, and the servo pattern is written sequentially. is there.

At the same time as or before the servo writing, the above-described first to third checking processes are performed, and when the servo write magnetic head 15 has come to be replaced, the operation is performed. In this case, if it is determined that there is an abnormality based on the check result, the equipment is automatically stopped to prevent continuous production of defective products. Further, it is desirable that a maintenance call can be promptly started by automatically issuing a so-called maintenance call by a communication means or the like.

In the above embodiment, a disk-shaped magnetic recording medium has been described, but the present invention is not limited to this, and it goes without saying that the present invention can be widely applied to so-called tape-shaped magnetic recording media and the like.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a servo write device according to one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a read signal in a first check of a servo write magnetic head.

FIG. 3 is a diagram showing an example of a read signal in a second check of the servo write magnetic head.

FIG. 4 is a diagram showing an example of a read signal in a third check of the servo write magnetic head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Floppy disk 3 Magnetic recording medium 10 Servo writing device 13 Spindle 15 Magnetic head for servo writing 16 Suspension 21 Load mechanism V1-V5 Output value

Claims (2)

[Claims] 1. A servo of a magnetic recording medium for writing a test signal to a magnetic recording medium by a servo write magnetic head for writing a servo signal for head positioning, reading the test signal and checking the performance of the servo write magnetic head. In the writing method, the performance check is performed at predetermined intervals of a magnetic recording medium by writing a test signal having a predetermined frequency and performing a level check that an output value obtained by reading the test signal is equal to or more than a specified value. A first check and a second check for writing a plurality of types of test signals having different frequencies and performing a resolution check that the ratio of the high frequency output value to the low frequency output value when reading out the test signal is equal to or greater than a specified value. And a test signal of a predetermined frequency is written and the output value when this is read Detecting the maximum value and the minimum value, the servo writing method for a magnetic recording medium and judging from the third check the ratio of the minimum value to perform modulation check is not less than a specified value to maximum. 2. The servo writing method for a magnetic recording medium according to claim 1, wherein the performance check of the magnetic head for servo writing is performed at the time of servo writing to each magnetic recording medium.