KR19990034746A - Track position information extraction method on magnetic recording device - Google Patents

Abstract

The present invention is to detect the track position information without distortion of the magnetic recording apparatus, and to record each servo sector containing the track position information so as to accurately detect the position of the track, which is an area where magnetic information is written or read on the magnetic recording apparatus. A method for detecting the position of a track on a magnetic recording device, which uses a gray code and multiple burst signals recorded at different positions, to detect continuous track position information, is provided between a track and another track following it. Detecting the magnitudes of the respective burst signals encountered in successive positions; Correcting a portion where the burst signal is distorted and calculating position information between tracks according to a predetermined operation; And detecting final track information by adding the gray code representing the position of the entire track section to the position information between the track and the track.

According to the present invention, by correcting the section in which the burst signal distortion occurs due to the flange effect in real time, incomplete restoration section is eliminated in reconstructing the burst signal into position information so that accurate position information can be detected.

Description

Track position information extraction method on magnetic recording device

The present invention relates to a method for obtaining accurate position information of a track on a magnetic recording apparatus such as a hard disk, and more particularly, in a magnetic recording apparatus in which a burst signal of different positions can be combined to detect and detect a position in a track. A method for calculating track position information.

1 to 3 are diagrams for explaining a conventional method of detecting the position of a track in a magnetic recording disk by using a burst signal. The magnetic recording disk is a track in which data is written or read, and the track is divided into several. And a servo sector located at the beginning of the sector and in which the position signal of the track is recorded.

1 illustrates a magnetic recording disk, which is divided into a track 100, a sector 110, and a servo sector 120. The track 100 is an area in which magnetic recording discs are divided into circles. Sector 110 is an area in which track 110 is vertically divided. The servo sector 120 is an area at the position where the new sector 110 starts, and includes position information that should be read when a head not shown in the figure follows the track position. Here, the servo sector 120 shown in the figure is continuously present on the same line of several tracks 100.

FIG. 2 illustrates the servosector 120 shown in FIG. 1 in detail. In four servo sectors located on the same line of four consecutive tracks, a portion 200 in which track positions are recorded in a gray code and a portion 210 in which four burst signals are regularly recorded at different positions are provided. It is included. Here, the gray codes are 2n-1, 2n, 2n + 1, and 2n + 2, respectively, and the burst signal is a combination of magnetization signals called A, B, C, and D so that the position of the track can be detected more accurately. Since the gray code is a coded method of discrete signals, for example, when the head, not shown in the figure, is located slightly closer to the 2n track toward the 2n track when moving along a track of 2n + 1 gray code, If the location information is detected, the location cannot be represented in more detail. Accordingly, track tracking may become unstable because the position of the head cannot be controlled to go to the track center.

3 is a graph reconstructing the magnitude of the burst signal 210 for each position of the track shown in FIG. 2. The horizontal axis of FIG. 4A is a gray code that discretely separates track positions, and the vertical axis is the magnitude of the burst signal. The magnitude depends on how many bits are converted during the analog / digital conversion of the burst signal. Here, the A and B burst signals have a phase difference of 180 degrees, and the C and D burst signals also have a 180 degree phase difference. A and C, B and D each have a phase difference of 90 degrees. For example, when the gray code of FIG. 4A corresponding to the servo sector 2n + 2 shown in FIG. 2 is 2, the A burst signal and the B burst signal at the center of the track are halfway between the maximum value and the minimum value of each burst signal. Where the C burst signal is the largest and the magnitude of the D burst signal is the smallest. This is based on the result of calculating the distribution of the A, B, C, and D signals distributed in the center of the track 2n + 2 of FIG. 2 by a predetermined method. For all positions other than the center of one track, the magnitudes of the A, B, C, and D burst signals as shown in FIG. 4A can be obtained. That is, it is possible to convert numerically the relation between positions in one continuous track and the burst signals A, B, C, and D corresponding thereto.

FIG. 4 illustrates a graph in which the magnitude of each burst signal of FIG. 3 is normalized or denormalized. In the predetermined scheme, first, the denormalized or normalized AB and CD signals are calculated as in Equation 1 below.

AB = A-B or AB = (A-B) / (A + B),

CD = C- D or CD = (C-D) / (C + D)

FIG. 5 is a graph in which more detailed track position information is detected using the normalized or denormalized burst signals shown in FIG. 4, where the horizontal axis is the gray code of each track and the vertical axis is the position within one track. The above position '0' means the track center, and the other values are off-center values.

In practice, there is a section such as 'f' in FIG. 5 in which the restoration of the burst signal is not properly performed due to the characteristics of the head not shown in the figure for detecting the position of the track and other detection environments, and thus an incorrect detection signal. Feedback can lead to incorrect track tracking or worse settling characteristics during seek.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a track position detection method of a magnetic recording apparatus in which an accurate position information is detected by eliminating an incomplete restoration section in restoring a burst signal to position information. There is this.

1 shows a magnetic recording disk.

2 illustrates the servo sector shown in FIG. 1 in detail.

FIG. 3 is a graph in which the magnitude of the burst signal shown in FIG. 2 is restored.

FIG. 4 is a graph normalizing or denormalizing the burst signals shown in FIG. 3.

FIG. 5 is a graph of detecting more detailed track position information using the normalized or denormalized burst signals shown in FIG. 4.

6 is a graph normalizing the burst signals of FIG. 3 in accordance with the present invention.

FIG. 7 is a graph of position information of a track calculated using FIG. 6.

8 is a flowchart of a method for calculating position information of a track according to the present invention.

On a magnetic recording disc having a track in which data is written or read, a sector divided by the track, and a servo sector located at the beginning of the sector to record the position signal of the track for achieving the above object. The method for detecting the track position by using a gray code for distinguishing the track and a plurality of burst signals for detecting the position of the track comprises: calculating magnitudes of burst signals of the track to be detected; Burst signal A, B, C, D having a phase difference of degrees

AB = A-B or AB = (A-B) / (A + B),

CD = C- D or CD = (C-D) / (C + D)

Normalizing or denormalizing as in; When AB = 0 or CD = 0, using the property that the CD passes the maximum or minimum point at the point AB is 0, kab is the correction factor taking the inverse of AB and the correction factor kcd taking the inverse of the CD Obtaining a; Recalculating AB and CD normalized using the correction coefficients kab and kcd in the AB and CD in the interval where AB = 0 and CD = 0; When the value obtained by adding CD to the AB is called PDT and the value obtained by subtracting CD from AB is called PDB, Equation 2 is performed for each track.

Interval 1: PDT * PDB <0, and if odd track, 2 * PES = AB

Interval 2: PDT * PDB <0, and even tracks, 2 * PES = -AB

Interval 3: PDB> 0, and if odd track, 2 * PES = -CD + 1

Interval 4: PDB <0, and if odd track, 2 * PES = CD-1

Interval 5: If PDB> 0 and even tracks, 2 * PES = -CD-1

Interval 6: If PDB <0 and even tracks, 2 * PES = CD + 1

Calculating continuous positional information PES between tracks, as in; And detecting the final track position information by adding the continuous position information of one track obtained from Equation 2 and the gray code which is a unique number of the track.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 6 illustrates a graph normalized or denormalized in a predetermined manner by using the magnitude of each burst signal in relation to the track position of FIG. 3. It calculates like Formula (1) mentioned above. In fact, in FIG. 3, each burst signal is distorted at the maximum and minimum values of each of the burst signals A, B, C, and D by a flange effect. Since the AB and CD also have a phase difference of 90 degrees, using the property that the CD passes the maximum or minimum point at the point AB is 0, kab is the correction coefficient at the point where CD = 0 and AB = 0 And kcd. As shown in Equation 3 below, the correction process is calculated in real time using the A, B, C, and D burst signals at the time of calculation only at AB = 0 and CD = 0. In other words, where AB and CD are not zero, the normalization process of Equation 1 is simply applied without performing correction as in Equation 3.

At CD = 0, kab = 1 / AB,

At AB = 0, kcd = 1 / CD

At AB = 0 and CD = 0, Equation 4 is obtained by recalculating the AB and CD signals by applying the above correction factor.

AB = kab * AB,

CD = kcd * CD

Equation 4 is applied to the portion where AB = 0 and CD = 0, and equation 1 is applied to the remaining portions to normalize the burst signals of AB and CD, as shown in FIG. A conversion named PDT and PDB is performed as shown in Equation 4.

PDT = AB + CD

PDB = AB-CD

From Equation 5, PES, which is more detailed position information for each track section, is calculated as in Equation 2 described above.

FIG. 7 is position information of a track calculated by applying FIG. 6 to a process similar to Equation 2. FIG. The track position information is the sum of the gray code value and the PES value obtained above. The abscissa in Fig. 7 is the position of the track, and the numbers 1, 2, 3, 4, and 5 show the gray codes that distinguish the tracks. In addition, the vertical axis | shaft of FIG. 7 is positional information in one track by a burst signal. In this case, '0' indicates center position information in one track, and other values indicate that the larger the values, the farther from the center of the track. If a head not shown in the figure is located at the center of a track with gray code 3, the track position information of the head is '3.0', and the position of the non-center track is '3.x' (where x is any Number). In FIG. 7, the discontinuous section shown in FIG. 5, which may occur when using a conventional burst signal restoration and use method according to a peripheral device environment, may be corrected to provide more accurate track position information.

FIG. 8 is a flowchart illustrating a method for calculating position information of a track shown in FIGS. 3, 6, and 7 according to the present invention. First, each of the burst signals A, B, C, and D described above at a position on the track is shown. Using the distribution, the magnitude of the burst signals is calculated according to a predetermined method (step 800). When the burst signals recorded while the magnetic recording disk is manufactured are restored to the magnitude signal, each of the burst signals has a phase difference of 90 degrees with each other. Among the recovered burst signals, signals having a phase difference of 180 degrees are subjected to a predetermined normalization or denormalization process as shown in Equation 1 (step 810). When the magnitude of each burst signal is the maximum or minimum, the waveform of the burst signal actually shows a gentle distortion due to the flange effect, so that a certain amount of distortion is generated to prevent false position detection accordingly. Correction is necessary (step 820). In the section where AB = 0 and CD = 0, a correction coefficient as shown in Equation 4 is obtained (step 830). The normalization process as in Equation 5 is performed again using the correction coefficient obtained in the above-described step (step 840). In step 850 and 860, a track and a continuous position between the tracks are detected. Finally, the position information between the gray code 200 recorded in the servo sector 120 and the track obtained using the burst signal 210 is added to calculate the position information without distortion at any position on the track (step 870). .

According to the present invention, by correcting the section in which the burst signal distortion occurs due to the flange effect in real time, incomplete restoration section is eliminated in reconstructing the burst signal into position information so that accurate position information can be detected.

Claims (1)

A gray code for distinguishing the tracks on a magnetic recording disk having a track on which data is written or read, a sector divided by the track, and a servo sector located at the beginning of the sector, in which a position signal of the track is recorded. And detecting the track position by using a plurality of burst signals for detecting the position of the track. Calculating magnitudes of burst signals of tracks to be detected; Burst signal A, B, C, D having a phase difference of 90 degrees AB = A-B or AB = (A-B) / (A + B), CD = C- D or CD = (C-D) / (C + D) Normalizing or denormalizing as in; When AB = 0 or CD = 0, using the property that the CD passes the maximum or minimum point at the point AB is 0, kab is the correction factor taking the inverse of AB and the correction factor kcd taking the inverse of the CD Obtaining a; Recalculating normalized AB and CD by multiplying the correction coefficients kab and kcd by the AB and CD, respectively, in the interval of AB = 0 and CD = 0; When the value obtained by adding CD to the AB is called PDT and the value obtained by subtracting CD from AB is called PDB, Equation 2 is performed for each track. Interval 1: PDT * PDB <0, and if odd track, 2 * PES = AB Interval 2: PDT * PDB <0, and even tracks, 2 * PES = -AB Interval 3: PDB> 0, and if odd track, 2 * PES = -CD + 1 Interval 4: PDB <0, and if odd track, 2 * PES = CD-1 Interval 5: If PDB> 0 and even tracks, 2 * PES = -CD-1 Interval 6: If PDB <0 and even tracks, 2 * PES = CD + 1 Calculating continuous positional information PES between tracks, as in; And Detecting the position of the track on the magnetic recording apparatus, comprising the step of detecting the final track position information by adding the continuous position information of one track obtained from Equation 5 and the gray code which is a unique number of the track. Way.