JPH0519203B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic recording medium for adjustment, and in particular to a magnetic head in a magnetic recording/reproducing apparatus using a disk-shaped magnetic recording medium such as a floppy disk or a magnetic tape. This invention relates to a recording medium for measuring head positioning accuracy for adjusting the position and angle of a head.

[Background of the Invention] Conventionally, for example, when adjusting the mounting position of a magnetic head in a magnetic disk device, a magnetic disk (magnetic disk for adjustment) on which special data is written is used.
was used to indirectly measure and adjust the position signal from the readout output waveform of the magnetic head.

However, in this method, output fluctuations due to recording unevenness of the adjustment magnetic disk,
There is a problem in that the measurement accuracy is not sufficient because it is susceptible to changes in the contact state between the magnetic head and the medium or the edge read output of the tunnel erase head. This will be explained in detail below based on the drawings.

FIG. 1 clearly shows the recorded signal of the measurement disk for ease of understanding, and the symbol ◯ indicates the center of rotation of the disk. Two pieces of data A and B centered on an eccentric point ○' a little distance from the rotation center ○ are recorded on this measurement disk.

If the position of the magnetic head H to be measured is the 38th track out of 77 tracks from 0 to 76, then the radial positions of 71.645+α and 71.645−α are based on the normal radius of track 38 of 71.645 mm. The two signals A and B mentioned above are recorded.

When this measurement disk is attached to the disk drive and read with the lead gap R of the head H located at the regular track 38, the detected voltage shows a cat's-eye waveform of e _A ≒ e _B as shown in Figure 2. Observed on a synchronoscope screen. Since the ratio of the detection voltages e _A and e _B changes in a constant relationship with the deviation of the head H from the normal track position,
Conversely, it is possible to measure the deviation of the head position from the ratio of the sizes of e _A and e _B. In addition, in FIG. 2, T indicates the period of one revolution of the magnetic disk.

However, conventional head position measurements using this cat's eye method have resulted in considerable measurement errors. The main causes of this measurement error are changes in the output of the magnetic medium, changes in the contact state between the head and the medium, and the edge readout output of the tunnel erase head (ERI and ER2 shown in Figure 1). A voltage fluctuation called modulation occurs in the voltage as shown in Figure 3, and this overlaps with the cat's eye detection voltage, resulting in a detection voltage as shown in Figure 4.
Even when e _A ′ and e _B ′ match the regular track, there is a difference in the magnitude of e _A ′ and e _B ′, which causes measurement errors.

As a solution to the above problem, JP-A-52-
There is an adjustment disk shown in Publication No. 69309.
As shown in FIG. 5, this adjustment disk roughly divides the adjustment tracks of adjustment disk 1 into about six groups, further divides each group into nine signals, and divides the first three signal sections into Beacon signals 3, 4, 5 consisting of
It is characterized by comprising three sets of position signals 4a, 4b, 5a, 5b, 6a, and 6b written offset to the inner and outer circumferences with respect to the track center of the adjustment track.

In the adjustment disk 1 described above, if the magnetic head (not shown) of the device to be adjusted is located at the adjustment track center 2, the position signals 4a, 4b, 5a, 5b, 6a, 6b are The reproduced signal waveforms 4c and 4d, 5c and 5d, 6c and 6d are
As shown in FIG. 6, the amplitudes are equally detected. Further, when the magnetic head has a radial positional deviation toward the outer circumferential side of the adjustment track, a reproduction signal as shown in FIG. 7 is detected, and the position signals 4a, 4 are detected.
Reproduction signals 4e and 4 of b, 5a, 5b, 6a, 6b
There is a difference in signal amplitude between f, 5e and 5f, and between 6e and 56f. Therefore, conversely, by detecting the position signal amplitude difference, the radial positional deviation of the magnetic head can be measured.

In this method, compared to the method using an adjustment disk as shown in FIG. Since the magnetic head is written at a considerable distance on the circumference, there remains the problem that errors in magnetic head position measurement due to the modulation cannot be avoided.

To solve this problem, it is possible to reduce the influence of the modulation by making the pitch of the position signals finer, but in this case, it becomes difficult to accurately detect each position signal. This will cause another problem.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in conventional magnetic recording media for adjustment, and to provide a magnetic recording medium for adjustment that has high positional deviation adjustment accuracy. Our goal is to provide the following.

[Summary of the invention]

The above-mentioned object of the present invention is to have a plurality of adjustment signals arranged symmetrically and alternately with respect to the center line of the adjustment position, and to adjust the positional deviation amount of the signal recording/reproducing element by the reproduced signal amplitude of the adjustment signals. In the adjustment magnetic recording medium to be detected, the adjustment signal includes information indicating where the adjustment signal is located on the center line, and information indicating which side of the center line the signal is located. This is achieved by an adjustment magnetic recording medium in which both are recorded in a distinguishable combination.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 8 is a diagram showing an example of signal writing on the adjustment magnetic disk, which is an embodiment of the present invention. In the figure, 1 is a magnetic disk for adjustment, 2 is its adjustment radial position, and 7 is a magnetic head to be measured. Further, C ₁ , C ₂ , . _. . C _o ; D ₁ , D ₂ , .

As the adjustment radius position 2, the position of the 38th track (R ₃₈ ) is selected as in the previous example.
In this case, the position detection signal of the above C group is 71.645−α
mm position, and the position detection signal of group D is 71.645
It will be recorded so that its center is at the +αmm position.

In addition, the length of each block of the position detection signals of the C group and D group is very short, for example,
It should be divided into 160 to 640 equal parts. Thereby, as will be described later, the influence of the modulation can be substantially eliminated. This situation will be explained with reference to FIG.

Figure 9 schematically shows the detection voltage when the influence of modulation is superimposed on the position signal.As the recording width b of a block becomes narrower, the difference in detection voltage between adjacent blocks becomes smaller. , indicating that the influence of modulation becomes smaller.

When performing position calculation by reading a large number of position detection signals as described above, it is necessary to check which position on the circumference each position detection signal is located at, and whether each position detection signal is located in the above-mentioned group C or D. It is necessary to identify which group it belongs to. This will be explained below using FIG. 10.

FIG. 10 shows an example of a position detection signal with markers for detecting each block.

As shown in the figure, each block consists of three elements: a synchronization signal section (VFO synchronization) 9, an identification (ADDRESS) section 10, and a data section 11. The identification section 10 records a group name to which the following data section 11 belongs and a signal for identifying the C group or the D group. The above group name means, for example, dividing the circumference into 8 groups, each group consisting of 20 blocks, 10 blocks in group C,
Refers to each block when 10 groups are assigned to Group D.

Furthermore, the signal for identifying the C group or the D group means, for example, that the data of each group is the tracking measurement data of the magnetic head (inner circumference side, outer circumference side) or the azimuth angle measurement data (+, -) refers to a signal indicating that the

The data section 11 is repeated using a reference frequency, and position and angle measurements are performed using the reproduction voltage of the data section 11, as in the conventional case. Further, the synchronization signal section 9 constitutes an introduction section for decoding the signal of the identification section 10.

For example, one group of the signals of the data section 11 is
In the case of 20 blocks, 16 blocks can be used for radial position signals and the remaining 4 blocks can be used for azimuth signals.

11 and 12 show other embodiments of the present invention, in which FIG. 11 shows a signal waveform of the adjustment magnetic disk, and FIG. 12 shows an example of signal writing.

In this embodiment, the circumference is divided into 1000 equal parts, for example, at the adjustment track position of the adjustment magnetic disk. It is desirable to increase the number of divisions as much as possible within the range that allows signal measurement. Further, the C group and D group of position detection signals are written symmetrically about the adjustment track 2 and alternately.

Here, each of the C group and D group signals is further divided into a plurality of signals as shown in FIG. Here, each of the plurality of divided signals is ₁ Cn, ₂ Cn,
We will call them …… _i Cn, ₁ Dn, ₂ Dn, … _i Dn.
A very small gap is provided between the signals of the C group and the signals of the D group, and is used as a break in the signal block during reproduction.

In Figure 12, one signal block is
They are divided into ₁ Cn to ₉ Cn and ₁ Dn to ₉ Dn, respectively. Note that ₉ Cn and ₉ Dn are used to record no signals and to distinguish between C and D signals during playback, but it goes without saying that ₁ Cn and ₁ Dn may also be used.

Also, out of the remaining 8 divisions, here are ₂
Cn, ₃ Dn at a different frequency from other signal sections, e.g.
The above ₂ Cn and ₃ Dn are 250KHz and the others are 125KHz, so the reproduction outputs are at different frequencies during reproduction. The reproduced output in this case is as shown in FIG. 11, and the reproduced output in the portions corresponding to ₂ Cn and ₃ Dn is small.

Therefore, the start of a position signal is detected by a break in the signal, and for example, when the second reproduction output is small, it is called a signal inside the center line, and when the third reproduction output is small, it is called a signal outside the center line. Thus, a predetermined signal can be detected. Furthermore, by providing a plurality of low reproduction output parts and arranging them to indicate positions on the circumference, it is possible to clarify the location where the signal is written when each signal is reproduced. be able to.

Here, if the numbers of the low reproduction output parts of the pair of opposing C and D signals are made equal, then
The average value of the reproduction output in this part is equal when the magnetic head is located on the center line, and unequal when the magnetic head is deviated from the center line, so the position of the magnetic head depends on the ratio of the two. The amount of deviation can be detected.

FIG. 13 shows still another embodiment of the present invention. Divide one round of the adjustment track into 1000 equal parts at this location, divide it into 8 large parts, and name them BLK1 to BLK8. Therefore, one BLK consists of 125 signal groups. One BLK signal section further consists of a START section consisting of 7 signal sections, a position signal detection section consisting of 60 signal sections, a position signal azimuth signal switching section consisting of 2 signal sections, and 52 signal sections. The azimuth signal section consists of 4 signal sections.
It consists of an END part. In addition, BLK1 includes
Two consecutive signals are written in the START section.

Therefore, as shown in Figure 13, 2 is added to the START section.
If consecutive signals of If the signal is detected, the switching signal to the azimuth signal,
The next 52 (26 pairs) azimuth signals and four no signals make it possible to detect the start of the next BLK.

In the above embodiment, it goes without saying that there is a shorter no-signal time between position signals or azimuth signals than in one signal section.

Also, the ratio of the above position signal and azimuth signal,
Alternatively, the length of the no-signal time may be arbitrarily changed within the range in which a signal can be captured, and the number of signal parts in one round can also be arbitrarily determined.

In each of the above embodiments, an example is shown in which the present invention is applied to a magnetic disk for adjusting the position of a magnetic head in a magnetic disk device, but the present invention is not limited to a magnetic disk device. Needless to say, it is also applicable to

Preferred embodiments of the invention are listed below.

(1) An adjustment magnetic recording medium in which an identification section as shown in FIG. 10 is provided in the adjustment signal, and information on the position of the signal section and information on the adjustment target are recorded therein.

(2) A magnetic recording medium for adjustment in which a characteristic part as shown in FIG. 11 is provided in the adjustment signal, thereby recording information on the position of the signal part.

(3) A magnetic recording medium for adjustment in which a signal portion having position information, a position signal, an azimuth signal, etc. as shown in FIG. 13 is provided in the adjustment signal.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a plurality of adjustment signals arranged symmetrically with respect to the center line of the adjustment position, and the position shift of the signal recording/reproducing element is caused by the reproduced signal amplitude of the adjustment signals. The adjustment magnetic recording medium for detecting the amount is configured so that the adjustment signal includes information on the position of the signal recording/reproducing element in the moving direction and information on the adjustment target, so that it is not affected by modulation and can be This has the remarkable effect of realizing an adjustment magnetic recording medium that enables accurate magnetic head position measurement.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of signal writing on a conventional adjustment magnetic disk, and FIG. 2 is a diagram showing the observed waveform.
Figure 3 is a diagram showing an example of modulation, Figure 4 is a diagram showing observed waveforms when modulation occurs,
FIG. 5 is a diagram showing an example of signal writing in another conventional example, FIGS. 6 and 7 are diagrams showing observed waveforms, and FIG. 8 is a diagram showing signal writing of an adjustment magnetic disk according to an embodiment of the present invention. FIG. 9 is a diagram showing the observed waveform. FIG. 10 is a diagram showing the detailed structure of the write signal. FIG. 11 is a diagram showing the signal waveform showing another embodiment of the present invention. FIG. 12 is a diagram showing an example of signal writing, and FIG. 13 is a diagram showing an example of signal writing and observation signals on an adjustment magnetic disk according to still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Magnetic disk, 2...Adjustment track center line, 7...Magnetic head, 9...Synchronization signal section, 1
0...Identification section, 11...Data section.

Claims (1)

[Claims] 1. Magnetic recording for adjustment, which has a plurality of adjustment signals arranged symmetrically and alternately with respect to the center line of the adjustment position, and detects the amount of positional deviation of a signal recording/reproducing element based on the reproduction signal amplitude of the adjustment signals. In the medium, in the adjustment signal, information indicating where the adjustment signal is located on the center line, and
A magnetic recording medium for adjustment, characterized in that information indicating which side of the center line the signal is located on is recorded in combination so that both can be identified.