JP2005063667A - Method for recording position signal and magnetic recording device using method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the width of a burst pattern is narrowed as compared with prescribed width due to the influence of erasing width by trimming the burst pattern width by DC erasing. <P>SOLUTION: The burst pattern width is trimmed by writing a high frequency signal whose erasing width is narrower. The high frequency signal pattern is erased by writing a signal having a reversed phase and the same frequency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic recording method and apparatus such as a flexible magnetic disk device and a rigid magnetic disk device.

  The position signal for head positioning in the magnetic recording apparatus is formed by discretely recording in advance on the magnetic recording medium a signal sequence (burst pattern, burst signal) that becomes all 1, for example. By arranging the burst signals in a staggered manner along the magnetic recording track direction, the amplitude difference between the pair of burst signals is converted as a shift amount in the track width direction during signal reproduction, thereby obtaining a positional shift amount of the magnetic head.

  For example, a conventional method for recording a positioning burst pattern is as shown in FIG. (A) is an actually written servo pattern, and (b) shows a timing chart of recording currents corresponding to the respective recording positions (1) to (4). A burst pattern 43 having a servo track pitch p is written along a center line 44 of the recording track using a recording / reproducing composite head on which a recording head 41 having a recording track width t and a reproducing head 42 are mounted.

  First, in (1), the first ½ of the A pattern is written, DC erasure is performed in the B and C areas, and the second ½ of the D pattern is written. Next, with the 1/2 servo track pitch shifted (2), the second half of the A pattern is written, DC erase is performed in the B area, the first 1/2 of the C pattern is written, D In this area, DC erase is performed. In (3), which is further shifted by 1/2 servo track pitch, DC erase is performed in the area A, the first 1/2 of the B pattern is written, the second 1/2 of the C pattern is written, DC erase is performed in the area. In (4), which is further shifted by 1/2 servo track pitch, DC erase is performed in the area A, the second half of the pattern B is written, the DC erase is performed in the area C, and the first of the pattern D is performed. Of 1/2 is written. Hereinafter, the operation returns to (1) and repeats this.

  As the magnetic recording density increases, the accuracy of the dimension of the burst signal in the track width direction becomes increasingly important. As shown in FIG. 4, the end of the burst signal once recorded is further erased (trimming 46). ), The edge (trimming edge 45) on the erasing side of the servo pattern is theoretically defined, and it is possible to record a signal having an accurate dimensional width that is not affected by the track width variation of the recording head. ing.

  Conventionally, the erasing (trimming) operation has been performed by direct current erasing. In this method, the recorded burst signal is erased so that a certain magnetic field is applied in one direction after moving to a predetermined track width dimension.

  However, the direct current erasing method has a drawback in that it erases a position signal recorded beyond the track width optically observed with a microscope or the like. This is due to the phenomenon of erasing bleeding, and is caused by the recording current value, the shape of the recording head, and the like. For example, in the conventional method shown in FIG. 4, when the erase bleeding width e exists in the burst pattern or the erase is performed more than necessary, the reproduction output of the position signal is recorded with a predetermined size. As a result, the positioning signal quality deteriorates and positioning accuracy deteriorates. If the positioning accuracy deteriorates, it becomes difficult to achieve a high recording density.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a position signal recording method in which deterioration of position signal quality is reduced, and a magnetic disk device on which the position signal is recorded.

  In the present invention, in order to achieve the above object, the following magnetic recording characteristics are used. As shown in FIG. 5, the width a that is recorded beyond the optical track width of the recording head tends to gradually decrease as the recording frequency increases. On the other hand, as shown in FIG. The width b that is erased more than the width tends to decrease in a region where the recording frequency is high. This is because the recording capability of the recording head deteriorates due to an increase in eddy current in the head.

  According to the magnetic recording characteristics described above, it can be said that the erasing method for defining the position signal width is more advantageous from the viewpoint of erasing blur width in high frequency writing than in direct current erasing. The above erasing method is called “high frequency erasing method”. Here, the frequency in the high frequency erasure should be determined by one of the following two methods.

  In the first determination method, it is desirable to perform the high-frequency erasure at a frequency fe that is at least twice the burst frequency fb in consideration of servo signal filtering described later. The second determination method is desirably in a frequency region (fe˜) in which the signal degradation r is 3 dB or more as compared with the signal intensity in the low frequency region in the frequency characteristics of recording and reproduction by the magnetic recording medium and the magnetic head. . This is because a signal having such a frequency is not easily recognized as a signal in the high-frequency erasure region, and seems to be erased.

  Burst signal reproduction is performed as follows. For servo signal reproduction, the servo signal is extracted by a low-pass filter for the purpose of noise removal or the like. Now, the high-frequency signal recorded by the high-frequency erasure is removed by this low-pass filter and should not be reproduced as a signal. Therefore, in principle, the conventional method is sufficient as the servo signal reproduction method.

  However, in actual magnetic recording, the high-frequency signal pattern includes more magnetization transition noise generated from the magnetization transition region than the low-frequency signal pattern, and this noise also includes low-frequency components. Therefore, there arises a problem that it cannot be removed by filtering. This problem is solved as follows.

  A signal having the same frequency as the recording frequency of the high-frequency erasure signal and a phase shifted by 180 ° (delayed or advanced) is recorded again in the high-frequency erasure area. When the phase is shifted by 180 °, writing is performed so as to cancel the previously recorded high-frequency signal, and as a result, the high-frequency signal is erased. This erasing method of the high-frequency signal pattern is called “counter erasing method”. Since the phase is shifted by 180 °, for example, the previous high frequency signal crest interferes with the signal trough caused by counter elimination, and the signal becomes almost zero. As a result, trimming with a smaller blur width than conventional DC erasure is performed.

  According to the present invention, it is possible to reduce degradation of position signal quality due to the presence of an erase blur width in a burst pattern or erasing more than a necessary dimension as seen in a conventional method. Accordingly, it is easier to increase the recording density, and the role of the present invention in increasing the storage capacity of the magnetic recording apparatus is extremely large.

(Example 1)
FIG. 1 shows a first embodiment of the present invention. FIG. 1A shows a servo pattern actually written, and FIG. 1B shows a timing chart of recording currents corresponding to the respective recording positions (1) to (4). This will be described with reference to the drawings.

A burst pattern 13 having a servo track pitch p is written along the center line 14 of the recording track using a recording / reproducing composite head on which a recording head 11 having a recording track width t and a reproducing head 12 are mounted. First, in (1), the second half of the A pattern is written, DC erase is performed in the B region, the first 1/2 of the C pattern is written, and high frequency erase is performed in the D region. Next, at (2) shifted by 1/2 servo track pitch, high frequency erasure is performed in the area A, the first 1/2 of the B pattern is written, the second 1/2 of the C pattern is written, and D In this area, DC erase is performed. In (3), which is further shifted by 1/2 servo track pitch, DC erase is performed in the area A, the second half of the pattern B is written, high frequency erase is performed in the area C, and the first of the pattern D is performed. Of 1/2 is written. Further, in (4) shifted by 1/2 servo track pitch, the first half of the A pattern is written, the high frequency erase is performed in the B area, the DC erase is performed in the C area, and the second of the D pattern is performed. Of 1/2 is written. Hereinafter, the operation returns to (1) and repeats this.

  As a result, as shown in (a), the upper edge of the burst pattern 13 is the writing edge, and the lower edge is the high-frequency erasing edge, and the amount by which the pattern width is reduced by trimming is less than that of the prior art.

(Example 2)
FIG. 2 shows a second embodiment of the present invention. FIG. 2A shows a servo pattern actually written, and FIG. 2B shows a timing chart of recording currents corresponding to the respective recording positions (1) to (4). This will be described with reference to the drawings.

A burst pattern 23 having a servo track pitch p is written along the center line 24 of the recording track using a recording / reproducing composite head on which a recording head 21 having a recording track width t and a reproducing head 22 are mounted. First, in (1), the current value is passed as it is in the A region as 0, DC erasure is performed in the B region, a C burst pattern is written, and high frequency erasure is performed in the D region. Next, by shifting the servo track pitch by 1/2 (2), high frequency erasure is performed in area A, burst pattern B is written, current value is passed as 0 in area C, and DC erase is performed in area D. I do. In (3) where the servo track pitch is further shifted by 1/2, DC erase is performed in the area A, the current value is passed as it is in the area B, the high frequency erase is performed in the area C, and the burst pattern of D is changed. Write. In (4), which is further shifted by 1/2 servo track pitch, A burst pattern is written, high frequency erasure is performed in the B region, DC erasure is performed in the C region, and the current value is passed as 0 in the D region. To do. Hereinafter, the operation returns to (1) and repeats this.

  As a result, as shown in (a), the upper edge of the burst pattern 23 becomes the writing edge, and the lower edge becomes the high-frequency erasing edge, and the amount by which the pattern width is reduced by trimming is smaller than in the prior art. In the method of the second embodiment, it is necessary that the track width t of the recording head is equal to or larger than the track pitch p. When this condition is not satisfied, the method of Example 1 is used.

(Example 3)
FIG. 3 shows a third embodiment of the present invention. FIG. 3A shows a servo pattern actually written, and FIG. 3B shows how to apply a recording current corresponding to each recording position (1) to (4). This will be described with reference to the drawings.

A burst pattern 33 having a servo track pitch p is written along the center line 34 of the recording track using a recording / reproducing composite head on which a recording head 31 having a recording track width t and a reproducing head 32 are mounted. First, in (1), the current value is passed as it is in the A region as 0, DC erasure is performed in the B region, a C burst pattern is written, and high frequency erasure is performed in the D region. Thereafter, the track position is not moved, and as shown in (1 '), in the area A to C, the current value is passed as it is, and in the area D, the high-frequency erasure pattern and the phase are passed. Is written with a pattern shifted by 180 °. Next, by shifting the servo track pitch by 1/2 (2), high frequency erasure is performed in area A, burst pattern B is written, current value is passed as 0 in area C, and DC erase is performed in area D. I do. After that, without moving the track position, as shown in (2 '), the pattern of high frequency erasure in (2) and the pattern whose phase is shifted by 180 ° are written in the area A, and in the areas B to D. Pass the current value as it is 0.

  Similarly, after the writing of each track shown in the second embodiment, so-called counter erasure is performed in a region where high frequency erasure has been performed. Thereby, as seen in (a), in the burst pattern 33, the upper edge becomes the write edge, the lower edge becomes the high frequency erase edge, and the temporarily written high frequency signal is finally erased, The amount by which the pattern width is reduced by trimming is smaller than in the prior art, and reading of magnetization transition noise is also eliminated. In the method of the third embodiment, the track width t of the recording head is required to be equal to or larger than the track pitch p as in the second embodiment. When this condition is not satisfied, counter erasure as in the present embodiment is used for the method of the first embodiment.

The figure which shows the timing of the servo pattern and recording current of Example 1 of this invention. The figure which shows the timing of the servo pattern and recording current of Example 2 of this invention. The figure which shows the timing of the servo pattern and recording current of Example 3 of this invention. The figure which shows the timing of the conventional servo pattern and recording current. FIG. 3 is an explanatory diagram showing a relationship between a recording frequency and a recording track width in consideration of recording blur. FIG. 5 is a characteristic diagram showing a relationship between a recording frequency f and a recording track width b in consideration of erasure bleeding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Recording head, 12 ... Playback head, 13 ... Servo pattern, 14 ... Recording head center line, 15 ... Erase pattern, 45 ... Trimming edge, 46 ... Trimming

Claims (8)

  A magnetic recording medium having a magnetic film on a substrate, a magnetic head provided facing the surface of the magnetic recording medium, and a magnetic recording / reproducing circuit for recording / reproducing signals on the magnetic recording medium by the magnetic head A positioning pattern is recorded on the magnetic recording medium of the magnetic recording apparatus, wherein a dimension of the positioning pattern in the width direction of the magnetic head is defined by high-frequency signal recording. Position signal recording method.   2. The position signal recording method according to claim 1, wherein a frequency in the high frequency signal recording is at least twice as high as a recording frequency of the position signal.   The frequency in the high-frequency signal recording is in a frequency region in which signal degradation is 3 dB or more compared to the signal strength in the low-frequency region in the frequency characteristics of recording and reproduction by the magnetic recording medium and the magnetic head. The position signal recording method according to claim 1.   After the high-frequency signal recording, the high-frequency signal recording is performed by superimposing the high-frequency signal on the same track, with the same frequency as the high-frequency signal recording, the phase being delayed or advanced by 180 °. The position signal recording method according to claim 1.   A magnetic recording medium having a magnetic film on a substrate, a magnetic head provided facing the surface of the magnetic recording medium, and a magnetic recording / reproducing circuit for recording / reproducing signals on the magnetic recording medium by the magnetic head A magnetic recording apparatus comprising: a means for recording the positioning pattern on the magnetic recording medium by defining the dimension of the positioning pattern in the width direction of the magnetic head by high-frequency signal recording. apparatus.   6. The magnetic recording apparatus according to claim 5, wherein the frequency in the high frequency signal recording is at least twice as high as the recording frequency of the position signal.   The frequency in the high-frequency signal recording is in a frequency region in which signal degradation is 3 dB or more compared to the signal strength in the low-frequency region in the frequency characteristics of recording and reproduction by the magnetic recording medium and the magnetic head. The magnetic recording apparatus according to claim 5. After the high-frequency signal recording, the high-frequency signal recording is performed by superimposing the high-frequency signal on the same track, with the same frequency as the high-frequency signal recording, the phase being delayed or advanced by 180 °. The magnetic recording apparatus according to claim 5.

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