JPS6120943B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head positioning device, and more particularly to a servo pattern for detecting the position of a magnetic head formed on a servo surface of a magnetic disk.

Generally, in a magnetic disk storage device, as shown in FIG. 2, correct positioning of a read/write magnetic head 1 with respect to a predetermined read/write track 2 is performed based on a servo pattern 3 formed on a servo surface. That is, one of a plurality of read/write tracks formed concentrically on the read/write surface.
If a positioning line 4 is formed on the servo surface so as to coincide with the center line of the two read/write tracks 2, and the servo magnetic head 15 scans the positioning line 4, then when the servo magnetic head 15 is located at position c in the figure, the positioning line 4 will be read. The write magnetic head 1 is properly positioned with respect to a predetermined read/write track 2. The positioning servo pattern 3 shown in FIG. 2 is a developed view of a part of the servo pattern formed concentrically on the magnetic disk servo surface shown in FIG. Directions are drawn by parallel vertical lines.
Therefore, when the magnetic disk shown in FIG. 3 rotates clockwise, the servo magnetic head 1 carried by the arm 16
5 relative to the servo pattern 3 is the direction of arrow A. Further, on both sides of the positioning line 4, an odd track 7 and an even track 8 are formed which are separated in the radial direction by other positioning lines 5 and 6. At both ends of the servo pattern 3, information 9, 14 is arranged spanning both tracks 7, 8 as shown in the figure.
Information 10,1 consisting of NN pole and SS pole between 14
1, 12, and 13 (hereinafter referred to as unit information) are arranged alternately in the circumferential direction in the odd track 7 and the even track 8.

On a servo pattern with such a configuration,
First, when the servo head 15 scans in the direction A at position a, the servo head reads out the servo signal shown at a' in the figure. Below, the servo signals read out when the servo head 15 scans the pattern in the A direction from positions b, c, d, and e with respect to the positioning line 4 are shown as b', c', d', and e', respectively. . In this case, the amount of deviation of the servo head 15 with respect to the positioning line 14 is proportional to the difference P1-P2 between the maximum values P1 and P2 of the read signals of the information 10, 11 (or 12, 13). Therefore, on the x-axis, the difference between the above maximum values P1-P
2 and the amount of deviation of the center line of the servo head 15 with respect to the positioning line 4 on the y-axis, the position signal shown in FIG. 2f is obtained.
In the figure, the widths of the odd track 7 and the even track 8 are each assumed to be h, so y
The upper limit of the axis is n/2 and the lower limit is -h/2, and when the position signal is 0, the center line of the servo magnetic head coincides with the positioning line 4 (Fig. 2 c, c'), so read/write is possible. The head 1 is arranged to be correctly positioned with respect to the target track 2.

However, if the number of servo tracks and read/write tracks is increased to improve the track radial recording density (TPI), or if the number of records in each track is increased to increase the circumferential recording density (BPI). When improved, if the conventional position detection servo pattern 3 is used as it is, a stable position signal as shown in FIG. 2(f) cannot be obtained, and accurate positioning cannot be performed. In other words, if there is a defective part on the servo surface,
The servo head scans over the defective area as shown in Figure 2.
Since servo signals different from a' to e' are read out and the difference in the maximum value is calculated, including the servo signals corresponding to the defective part, the obtained position signal is extremely distorted, unlike in Figure 2 f. Become. Also, as density increases, the servo head will always be on the odd track 7.
It is not always necessary to scan parallel to the even track 8 (direction A in Fig. 2); for example, when scanning across the odd track and even track 8, unnecessary signals may be read out, or conversely, unnecessary signals may be read out. Sometimes the signal may not be read out.
The necessary and sufficient number of signals shown in e′ cannot be obtained.
Furthermore, the core width dimension of the conventional servo head is made smaller than the width dimension of the servo track in order to prevent other unrelated information from being read. However, when the servo head is located in the odd track 7 or even track 8, The center line of the head was never on the center line of the track, and in FIG. 2f, for example, the curve did not reach its maximum at +h/2.

In this way, with conventional servo patterns, the higher the track density, the more the waveform of the position signal (Fig. 2 f) becomes distorted, making it impossible to obtain a stable position signal waveform with good linearity based on point O. First, it has been difficult to accurately position the read/write magnetic head with respect to a predetermined read/write track.

An object of the present invention is to improve the linearity of position signals as the density of magnetic disk devices increases. A magnetic head positioning system in which concentric positioning lines are formed on the servo surface of a magnetic disk so as to match the positioning lines, and positioning unit information is arranged in servo tracks formed between the concentric positioning lines. 2n pieces for one read/write track (however, n≧2) in the servo pattern for
The width of each servo track is selected to be 1/n of the width of the servo magnetic head core, and the concentrically adjacent n
A plurality of radial alignment information formed by n pieces of unit information aligned in the radial direction of the servo tracks are formed spaced apart in the circumferential direction of the servo surface, and these pieces of alignment information are This is achieved by a magnetic head positioning servo pattern characterized in that the magnetic head positioning servo patterns are arranged in a stepped manner and are sequentially shifted one step at a time in the radial direction.

The present invention will now be explained by way of examples with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram of a servo pattern for positioning a magnetic head according to the present invention. Read/write track 3 targeted by read/write magnetic head 30
1 is formed concentrically with other tracks on the read/write surface of the magnetic disk. On the other hand, the servo tracks 41, 42, 43, 4 are written with positioning information for arranging the read/write magnetic head 30 at the correct position with respect to the target track 31.
4 is formed concentrically with other servo tracks on a servo surface different from the read/write surface. Furthermore, the positioning line 45 forming the boundary of each servo track coincides with the center line L of the read/write track 31, and the width dimensions of the read/write head, the read/write track, and the servo track are different from the core width dimension of the servo magnetic head. The read/write head 30 is correctly positioned with respect to the target track 31 when the center line of the servo magnetic head coincides with the positioning line 45 (FIG. 2c). There is. In FIGS. 2a to 2e, the left side shows a servo magnetic head, and the right side shows a read/write magnetic head whose width is half that of the servo magnetic head.

The magnetic head positioning servo pattern 40 according to the present invention has N
It consists of positioning information consisting of poles and south poles. There are two servo tracks on each side of the positioning line 45, namely servo tracks 41, 42 and 43.
and 44 are formed, and other positioning lines 46, 47, 4 are formed.
Each track is limited by 8,49.

At both ends of the servo pattern 40, information 50, 51 spanning four servo tracks 41, 42, 43, 44 is arranged, and between both ends radial alignment information consisting of two pieces of unit information spanning between adjacent servo tracks. 52, 53, and 54 are arranged radially offset by the width dimension of the servo track. The arrangement of information regarding each servo track 41 to 44 will be described in detail as follows. That is, regarding the servo track 41, there are areas 60 and 61 in which no information is written, and the alignment information 55 is part of the information of the positioning servo pattern for other read/write tracks. Further, regarding the servo track 42, areas 62 and 63 where no information is written are continuous and the servo track 4
Part of the alignment information 53 and 54 that spans 1 and 43 is written. Regarding the servo track 43, first a part of the alignment information 52 that spans the servo track 44 is written, then areas 64 and 65 where no information is written are written, and finally a part of the alignment information 54 that spans the servo track 42 is written. It is written. Regarding the servo track 44, 1 of the alignment information 52 spanning the servo track 43
part is written, then part of the information 56 of the positioning pattern for other read/write tracks is written, and then a part of the information 56 of the positioning pattern for other read/write tracks is written, and then an area 6 where no information is written is written.
6 and 67 are formed in succession.

As described above, by configuring the servo pattern according to the present invention, the number of servo magnetic heads is two or three.
The positioning line 45 is scanned across two servo tracks (Fig. 2 a to e), and servo signals consisting of four signals A, B, C, and D are sent to the positioning line 45 as shown in Fig. 2 a' to d'. It can be read out at each position, resulting in the position signal shown in FIG. 2f. In this case, the center line of the servo magnetic head is the positioning line 4.
5 (FIG. 2c), as shown in FIG. 2c', unlike the other a', b', d', and e', no signal corresponding to B is generated. Therefore, it is known in advance to compare the maximum values of signals A and C on both sides of the O signal,
The maximum value of an erroneous signal based on a defective portion of the servo surface is no longer compared. Furthermore, since four servo tracks are used for positioning on one read/write track, unlike the conventional two servo tracks, a necessary and sufficient number of signals can be read out. Furthermore, since the core width of the servo head can be made twice the track width, the positioning line 45
On the other hand, a stable servo signal can be read out even if the head deviates to both extreme positions.

In this way, the servo signals whose maximum values should be compared can be determined in advance, and only the necessary number of signals of stable magnitude can be read out, so the waveform of the obtained position signal is also similar to that of the read/write track. It is possible to obtain a position signal waveform that is stable and coincides with the actual position of the write head and has extremely high linearity using the O signal as a reference.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a servo pattern for positioning a magnetic head according to the present invention, and FIGS. 2 and 3 are an explanatory diagram and a plan view of a conventional servo pattern. 30... Read/write magnetic head, 31... Read/write track, 40... Servo pattern for magnetic head positioning, 41, 42, 43, 44...
...Servo truck, 45, 46, 47, 48, 4
9...Positioning line, 52, 53, 54...Radial alignment information.

Claims (1)

[Claims] 1. Each concentric positioning line is formed on the servo surface of the magnetic disk so as to coincide with each center line of the concentric read/write track formed on the read/write surface of the magnetic disk, and the positioning lines are formed between the positioning lines. Regarding one read/write track in a magnetic head positioning servo pattern in which positioning unit information is arranged in a servo track,
2n (n≧2) servo tracks are formed in correspondence, the width of each servo track is selected to be 1/n of the servo magnetic head core width, and the n servo tracks concentrically adjacent to each other are A plurality of radial alignment information formed by n pieces of unit information aligned in the radial direction are formed spaced apart in the circumferential direction of the servo surface, and these alignment information are aligned in the radial direction by the width dimension of the servo track. A servo pattern for positioning a magnetic head, characterized in that the servo pattern is arranged in a stair-like manner with one track at a time.