JPH0727699B2 - Magnetic disk device - Google Patents

Description

The present invention relates to a magnetic disk device for recording and / or reproducing a signal using a recording medium magnetic disk.
More specifically, the present invention relates to a magnetic disk device that can easily seek (search) a target track.

[Prior Art and its Problems] As a typical method for positioning a head on a desired track in a fixed magnetic disk device, a servo surface servo method,
There are three methods: an encoder method and a method in which the head is moved by the number of step pulses by a step motor.

By the way, the above-mentioned first servo surface servo system has a drawback that the disk utilization efficiency is low and a device for forming recording on the servo surface is expensive because one surface of the disk is used exclusively for servo. Have. The second encoder method has the disadvantage that the device is inevitably expensive due to the complicated structure of the encoder. The third step pulse method has a drawback that high speed seek is difficult.

On the other hand, when seeking the target track, the head may read the address written in advance on the track to position the head on the target track. However, as the number of tracks increases, the number of bits of the address signal inevitably increases, which makes it difficult to quickly read the address signal while sending the head in the radial direction of the disk.

Further, the ratio of the area for recording the track address to one track is increased, and the ratio of the area for recording the data other than the track address is decreased.

Therefore, an object of the present invention is to provide a magnetic disk device capable of narrowing a recording area of a signal for track recognition, that is, track discrimination, and quickly and accurately reading a signal for track recognition. It is in.

[Means for Solving the Problems] To achieve the above object, the present invention provides a recording medium magnetic disk having a plurality of tracks, a rotating means for the disk, and a head for converting a signal in relation to the disk. And a head moving means for moving the head in the radial direction of the disk, the plurality of tracks are divided into a plurality of groups, and the plurality of groups are at least first, second, Magnetization regions are provided at first and second angular positions of the first track for recognizing the first track, respectively, and have third and fourth tracks, respectively. For the purpose of recognition, a magnetized region is provided at each of the first and second angular positions of the second track, and a magnetized region is also provided at the third angular position. A magnetized region is provided at each of the second and third angular positions of the third track for recognizing the third track, and at each of the second angular position for recognizing the fourth track. The magnetic disk device is characterized in that a magnetized region is provided and the first, second and third angular positions are determined so as to be adjacent to each other in this order.

The correspondence between the present invention and the embodiments will be described. The first, second, third and fourth tracks of the present invention are tracks T1, T2, T13 and T14 of the embodiment, and The second and third angular positions are θ0, θ1, and θ2.

[Operations and Effects of the Invention] The present invention has the following operations and effects.

(A) In each group, the first and second tracks are first
The first and second halves of the group are distinguished by providing a magnetized region at the angular position of 1 and no magnetic region at the first angular position on the third and fourth tracks. Further, the arrangement of the magnetized regions other than the first angular position is the same on the first and fourth tracks, and the same on the second and third tracks. Therefore, the number of magnetized regions for identifying a plurality of tracks can be reduced, and the width of the signal recording region for track recognition can be narrowed. In short, a plurality of tracks are divided into groups, and the group is further divided into the first half and the second half, so that a plurality of tracks can be identified with a small number of magnetized regions.

(B) Since the width of the signal recording area for track recognition is narrowed, this reading can be performed quickly.

(C) The first and fourth tracks have magnetized regions at the second angular positions, and the second and third tracks have magnetized regions at the second and third angular positions. That is, the number of magnetized regions regularly increases and regularly decreases. As a result, even if a read error occurs in the magnetized area, a large error does not occur.

[Embodiment] Next, a fixed magnetic disk device according to an embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a recording medium magnetic disk 1 having high rigidity is fixed to a hub 2, and the hub 2 is connected to a disk motor 3. The motor 3 is driven by the control drive circuit 4 to rotate the disk 1 at high speed.

The magnetic head 5 is supported by an arm 6, and the arm 6 is connected to a voice coil motor 7. The voice coil motor 7 is a known one composed of a magnet and a coil. The voice coil motor 7 moves the arm 6 in an arc shape by the electric current flowing through the coil, and moves the head 5 at the tip of the arm 6 in the radial direction of the disk 1. is there.

By the way, the disk 1 has a large number of tracks (cylinders) 8 concentrically, and data is recorded in each track 8 in a predetermined track format. The track format is a large number (16 in this example) of data sectors and the first
It has a large number (16 in this example) of servo sectors 10 indicated by hatching in the figure. In addition, the servo sector 10 of each track 8
Are arranged at angular positions extending radially of the disk 1.

FIG. 2 is a development view of the track 8 for explaining the servo sector. The servo sector of each track 8 is arranged between data sectors, and has a sync signal area, a track recognition code area, a positioning servo signal area, and a guard (protection).
And a region. The sync signal area includes a magnetization pattern recording area and a DC erasing area. The servo signal is composed of a servo burst A, which is offset to one side of the center line of the track 8, and a servo burst B, which is offset to the other side.

FIG. 3 shows a pattern of the sync signal recorded in the sync signal area and the track recognition code recorded in the track recognition code area of FIG. The sync signal is composed of four magnetized regions 10 arranged at the same angular position on each track 8 and separated from each other, and a DC erase region 10a which determines the sync position. The track 8 of the disc 1 is divided into a number of track groups, and the same track recognition code is recorded for each track group. That is, the pattern of the track recognition code of the first track group from track T0 to track T15 and the pattern of the track recognition code of the second track group from track T16 to T31 shown in FIG. 3 are the same.

Further, the same track group is further divided into two. Now, taking the first track group as an example, the tracks T0 to T15 are divided into two tracks, a front half track T0 to T7 and a rear half track T8 to T15. Front half truck for the purpose of getting a flag to distinguish the front half from the rear half
The magnetized area 11 is provided at a position corresponding to the rotational angular position θ0 of the disk 1 of T0 to T7, and the magnetized area is not provided at the same angular position θ0 of the rear half tracks T8 to T15. The track T0 is only provided with a magnetized region 11 as a track identification code, and the track T15 is not provided with any magnetized region. The tracks T1 to T14 have first to seventh magnetized regions 12 to 18 for distinguishing them from adjacent tracks. The magnetized regions 10 to 18 may not be formed so as to extend over a plurality of tracks but may be formed so as to be divided at the boundary region of each track 8. When the magnetized regions 10 to 18 are provided by using the head 5 shown in FIG. 1, the magnetized regions 10 to 18 are necessarily divided at the boundary region of each track.

The first and fourteenth tracks T1 and T14 have only the first magnetized region 12 at the first angular position θ1.

The second and thirteenth tracks T1, T13 have the first angular position θ1.
In the second angular position θ2 in addition to the first magnetized region 12 of
Has a magnetized region 13.

The third and twelfth tracks T3 and T12 have first and second magnetized regions 12 and 13 at the first and second angular positions θ1 and θ2, respectively, and at the third angular position θ3. It has three magnetized regions 14.

The fourth and eleventh tracks T4 and T11 have a fourth magnetized region 15 at the fourth angular position θ4 in addition to the first to third angular positions θ1 to θ3.

The fifth and tenth tracks T5 and T10 have a fifth magnetized region 16 at the fifth angular position θ5 in addition to the first to fourth angular positions θ1 to θ4.

The sixth and ninth tracks T6 and T9 have a sixth magnetized region 17 at the sixth angular position θ6 in addition to the first to fifth angular positions θ1 to θ5.

The seventh and eighth tracks T7 and T8 have a seventh magnetized region at a seventh angular position θ7 in addition to the first to sixth angular positions θ1 to θ6.
Has 18.

In the group next to tracks T16 to T31, track T0
Magnetized regions 10 to 18 are repeatedly formed in exactly the same pattern as the group of ~ T15.

Magnetized area 1 as track recognition code on tracks T0 to T15
If 1 to 18 are provided in the pattern shown in FIG. 3, the track T0
~ T15 can be completely distinguished.

In the track recognition code area, as shown in FIG. 3, position detection signals Z1 and Z2 for detecting the track T0 (track zero) position are recorded. Z1 on track zero T0,
Both the Z2 and the other tracks are recorded and one is recorded.

Referring again to FIG. 1, the write circuit 19 and the read amplifier 20 are connected to the head 5. The read data forming circuit 21 connected to the read amplifier 20 is a circuit that waveform-shapes the read output of the data area of the track 8 to form read data (read pulse).

The position signal forming circuit 22 for obtaining the position information of the head 5 with respect to the center of the track 8 based on the reading of the servo bursts A and B of FIG.
Connected to 20. The read amplifier 20 is further connected to a comparator 23 for reading the sync signal area and the magnetized areas 10 to 18 of the track recognition code shown in FIG. A timing signal generator 24, a flag detection latch circuit 25, and a counter 26 are connected to the output of the comparator 23.

The timing signal generator 24 detects the sync signal area recorded in the servo sector of FIG.
Notify the CPU or microcomputer 27. The timing signal generator 24 is further shown in FIG. 6 (B) in order to detect the presence or absence of the magnetized area 11 shown in FIG. 3 of the track recognition code.
The flag extraction timing signal shown in FIG.
To send the counter control signal shown in FIG. 6 (C) to the counter 26 by line 30 to extract the corresponding signals of the magnetized regions 12-18 in the figure, and to extract the servo bursts A and B shown in FIG. Timing signals are sent to the position signal forming circuit 22 by lines 31 and 32.

The flag detection latch circuit 25 responds to the output pulse of the comparator 23 of FIG. 6 (A) only while the flag extraction timing signal shown in FIG. 6 (B) is at a high level. That is, the output pulse 11 of the comparator corresponding to the magnetized region 11
In response to a, a high level latch output or flag is generated, as shown in FIG. 6 (D), which is sent to microcomputer 27 on line 33.

The counter 26 responds to the output pulse of the comparator 23 of FIG. 6A only while the counter control signal shown in FIG. 6C is at a high level. That is, the comparator output pulses 12a-18a of FIG. 6 (A) corresponding to the magnetized areas 12-18 of the track recognition code of FIG. 3 are counted and the count output shown in FIG. 6 (E) is output to the 3-bit line 34. To occur. The timing signal generator 24 includes a counter 26 and a flag detection latch circuit.
A reset signal is supplied to 25 in response to the detection signal in the sync signal area shown in FIGS. Therefore, the counter 26
Is a track identification code (magnetized area 12 ~
18) is counted. 7 in the period before t1 in Fig. 6
Since seven comparator output pulses 12a to 18a are generated corresponding to the magnetized regions 12 to 18, the output of the counter 26 becomes a binary number [111], and three pulses are output after the time t1. 3 pulses 12 based on the detection of magnetized regions 12, 13, 14
Since a, 13a, and 14a have occurred, the output of the counter 26 is a binary number [011]. Now, tracks T0 to T7 in FIG.
Paying attention to, the counter 26 corresponds to the tracks T0 to T7, [000] [001] [010] [011] [100] [101] [110]
By generating the output of [111], the eight tracks T0 to T7 can be completely distinguished. In order to distinguish the eight tracks T0 to T7, a 3-bit binary number is generally recorded on the disc 1. However, in the disc 1 of this embodiment, the discrimination signal (address) of the track 8 is not recorded in binary, and the disc
Tracks are distinguished by changing the number of magnetized regions 12 to 18 as shown in the figure. Therefore, eight tracks T0 ~
Seven magnetized regions 12-18 are required to distinguish T7. Since the magnetized regions 12 to 18 are arranged so as to gradually increase and decrease, it is possible to detect the track recognition code with few errors. That is, since the magnetized regions 12 to 18 gradually increase and decrease, a large error is unlikely to occur when the counter 26 counts the number of magnetized regions 12 to 18.

The distinction between the front half group of the tracks T0 to T7 and the rear half group of the tracks T8 to T15 is achieved by the presence or absence of the magnetized region 11. The microcomputer 27 performs the following conversion by the software included therein. When the flag of the output line 33 of the flag detection latch circuit 25 is logical [1] corresponding to the presence of the magnetized region 11, the output of the counter 26 is used as the track identification data as it is. That is, in the tracks T0 to T7, the magnetized regions 12 to 12 formed by the counter 26 shown in FIG.
The 18 read outputs become the track identification data as they are. On the other hand, when the flag is logical [0] because there is no magnetized area 11, the operation corresponding to the 15-counter output value in decimal is performed. That is, track T8 corresponds to 15-7 = 8, track T9 corresponds to 15-6 = 9, track T10 corresponds to 15-5 = 10, track T11 corresponds to 15-4 = 11, track Equivalent operation as 15-3 = 12 corresponding to T12, 15-2 = 13 corresponding to track T13, 15-1 = 14 corresponding to track T14, and 15-0 = 15 corresponding to track T15 Is done in binary. As a result, the 15 tracks T0 to T15 can be completely distinguished by the eight magnetized regions 11 to 18.

The seek operation for moving the head 5 from one track group to the target track of another track group will be described later.

The position signal forming circuit 22 of FIG. 1 is a circuit for forming a position signal indicating whether or not the head 5 is positioned so as to match the center of the target track 8. The position signal forming circuit 22 comprises first and second peak hold circuits 36 and 37, two differential amplifiers 38 and 39, and a changeover switch 40 as shown in FIG. The first peak hold circuit 36 extracts the peak of the read signal of the servo burst A shown in FIG. 2 obtained from the read amplifier 20 by the timing signal on the line 31, holds and outputs it. Second
The peak hold circuit 37 of FIG. 2 extracts the peak of the read signal of the servo burst B shown in FIG. 2 obtained from the read amplifier 20 by the timing signal of the line 32, holds it, and outputs it. The pair of differential amplifiers 38 and 39 both determine the difference between the outputs of the first and second peak hold circuits 36 and 37, but the first and second peak hold circuits 36 have opposite polarities. , 37 connected.
This is because the servo bursts A and B are written so as to be shared by two tracks as shown in FIG.
This is to correct that the direction of the servo bursts A and B, which is offset with respect to the track center, changes for each track. A signal indicating whether the track is odd or even is given from the microcomputer 27 to the changeover switch 40 of the position signal forming circuit 22 by the line 41. When the head 5 is located on an even track, the first differential amplifier 38
From the output of the second peak hold circuit 37 to the first
The signal obtained by subtracting the output of the peak hold circuit 36 is sent via the switch 40, and when the head 5 is located on an odd track, the output of the second differential amplifier 39, that is, the output of the first peak hold circuit 36. A signal obtained by subtracting the output of the second peak hold circuit 37 from is output via the switch 40. As shown in FIG. 7, the outputs of the differential amplifiers 38 and 39 become zero when the center of the track 8 and the center of the head 5 are coincident with each other, and when a track deviation occurs, it becomes a value corresponding to this deviation. The position signal forming circuit 22 is connected to the control circuit 43 of FIG. 1 by a line 42 for position servo.

The track zero detection circuit 60 detects the track zero detection signals Z1 and Z2 from the output of the comparator 23 and outputs a signal indicating whether or not the track is zero to the microcomputer by a line 61.
Send to 27. In order to determine the timing of extracting the track zero detection signal, the track zero detection circuit 60 uses the line 62
Is connected to the timing signal generating circuit 24.

The microcomputer 27 moves the head 5 to the target track designated by the track command signal given by the line 44.
Controls the positioning of the. For this reason, the microcomputer 27 uses the 8-bit seek data line 45 and D /
It is connected to the control circuit 43 via the A converter 46 and the line 47, and is also connected to the control circuit 43 by the seek direction signal line 48 and the mode instruction signal line 49. line
The seek data 45 is 8-bit data corresponding to the head movement amount required to move the head 5 to the target track by the voice coil motor 47, and includes seek speed information. The D / A converter 46 converts the seek data into an analog signal corresponding to the moving speed of the head 5 and sends it to the control circuit 43. In the positioning mode after the seek is completed, the D / A converter 46 generates a position indication reference signal (for example, zero volt).

The seek direction signal on the line 48 is for distinguishing whether the head 5 is moved inward or outward of the disk 1.

The mode instruction signal on the line 49 is a signal for distinguishing between the seek mode and the positioning (tracking) mode.

The speed sensor 50 is composed of a speed detecting coil that moves in the magnetic field together with the coil of the voice coil motor 7 and generates a voltage corresponding to the moving speed and moving direction of the head 5, and sends a speed signal to the control circuit 43 via the line 51. give.

The control circuit 43 includes a position control error amplifier 52 and a speed control error amplifier 53, as shown in principle in FIG. One input terminal of the position control error amplifier 52 is connected to the position signal line 42 via the switch 54, and the other input terminal is connected via the contact a of the switch 55 or via the contact b of the inverting circuit 56 and the switch 55. Is connected to the output line 47 of the D / A converter 46 shown in FIG. One input terminal of the speed control error amplifier 53 is connected to the speed signal line 51, the other input terminal is connected to the output terminal of the error amplifier 52 of the preceding stage, and the output terminal is connected via the drive circuit 57 in FIG. It is connected to the voice coil motor 7.

The switch 55 is controlled by the seek direction signal on the line 48, and the contact b is turned on when the seek direction signal indicates the movement of the head 5 from the inner circumference to the outer circumference of the disk 1 (for example, high level). And a state indicating that the head 5 is moved from the outer circumference to the inner circumference (for example, low level)
At the time of, the contact a is turned on.

Switch 54 is controlled by a mode indication signal on line 49.
When the mode instruction signal indicates the seek mode, that is, the speed control mode (for example, high level), the switch 54 is turned off, and the mode instruction signal is position control (tracking control).
The switch 54 is turned on in the state (for example, low level) indicating.

The voice coil motor 7 in FIG. 1 has a stopper 58. This stopper 58 restricts the movement of the head 5 to the outside of the outermost track zero of the disk 1 significantly.

[Operation] A seek in this disc device is performed with reference to the track zero at the outermost periphery of the disc 1. Therefore, the disk 1 is rotated in response to power-on or a calibration command, and the head 5 is positioned at track zero. That is, a command is generated by the microcomputer 27 to move the head 5 in the outer peripheral direction of the disk 1 in synchronism with the power-on, and the voice coil motor 7 is controlled so that the head 5 faces the track zero. When the head 5 moves toward the track zero, the stopper 58 limits the movement of the head 5 to the outer periphery of the track zero. Thereafter, the head 5 is moved so as to obtain the track zero detection signals Z1 and Z2, whereby the track zero is sent from the detection circuit 60 to the microcomputer 27 on the line 61, and the microcomputer 27 The movement control of the head 5 is stopped. After that, the head 5 is positioned at the center of the track T0 based on the position signal detected by the servo bursts A and B. Then, the track address counter built in the microcomputer 27 is reset. This address counter outputs a value corresponding to the position of the head 5 on the disk 1 with reference to the track T0.

By the way, assuming that the track recognition codes are sequentially and accurately read from all the tracks from the outer circumference of the disk 1 toward the inner side from the track T0 to the track Tn, the output of the flag detection latch circuit 25 and the output of the counter 26 Based on the above, the conversion code output corresponding to the decimal numbers 0 to 15 can be periodically obtained in the microcomputer 27 as shown in FIG. The conversion code output is the above-mentioned 15-counter value. However, at the time of actual high-speed seek, the head 5 is moved diagonally across the track 8 as shown in FIG. 8 and the servo sectors are arranged in a scattered manner, so it is impossible to read the track identification code from each track. Is. However, the maximum moving speed of the head 5 is set so that the track recognition code can be read at least once (preferably twice or more) within the 16-track group. As a result, the switching of the track group is controlled by the microcomputer.
It becomes possible to judge at 27. When the head 5 is moved to the target track, the head 5 can be perfectly positioned on the target track if the number of the passed track groups and the code of the target track in the group to which the target track belongs can be known. .

Next, the operation of moving the head 5 from the track T0 to the track T46 will be described in principle with reference to FIG. When the target track T46 is given to the microcomputer 27, the microcomputer 27 determines the current position of the head 5. Since it is assumed that the current position of the head 5 is the track T0, the microcomputer 27 sets the target track.
The difference T46-T0 = 46 between T46 and the current track T0 is calculated. From this, it can be seen that the number of moving tracks of the head 5 is 46. The microcomputer 27 creates seek data (seek velocity data) and seek direction signals that match the number of moving tracks 46. That is, seek data (seek velocity data) having information on the current value of the voice coil motor 7 necessary for moving the head 5 at high speed by 46 tracks is sent to the 8-bit line 45. An analog signal corresponding to this seek data is obtained from the D / A converter 46, and the voice coil motor 7 enters a control state corresponding to this analog signal. Since the speed control circuit using the speed sensor 50 is provided, speed control is performed so that the speed designated by the seek data and the speed detected by the speed sensor 50 become equal. As mentioned above, at least 1
The maximum movement speed of the head 5 is limited so that the track recognition code can be read.

When the seek data (speed data) for moving the head 5 to the target track T46 is determined and the movement of the head 5 is started, since the disk 1 is rotating, a spiral head scanning locus is generated on the disk 1 and the head 5 moves. Crosses the track 8 diagonally as indicated by arrow 59 in FIG. The position where the head 5 crosses the track 8 is not always the servo sector. Figure 9 shows tracks T6, T12, T19, T27, T3
Indicates that the track recognition code of the servo sector can be read when the head 5 crosses 6, T42, T45, and T46, and the track recognition code cannot be read when the head 5 crosses other tracks. .

When the head 5 crosses the track T6 and the flags and counter outputs corresponding to the magnetized regions 11, 12, 13, 14, 15, 16, 17 shown in FIG. 3 are given to the microcomputer 27 from the lines 33, 34, The microcomputer recognizes that it is the track T6, and the remaining head movement amount T46-T
6 = 40 is obtained, and new seek data (seek velocity data) suitable for this movement amount 40 is formed and output to the line 45. As a result, the head 5 always moves at the optimum speed. Heads 5 on tracks T12, T19, T27, T36, T42, T45
Similarly, new seek data (seek velocity data) is also formed when the track recognition code is read across. The moving speed of the head 5 is such that the track recognition code can be obtained at least once in the first track group of T0 to T15, the second track group of T16 to T31, and the third track group of T32 to T47. Since it has been determined, the transition of the track group can be known by the change in the value of the detected track recognition code. That is, the microcomputer 27
It is assumed that there is a transition of the track group when the conversion code output of FIG. 9 based on the flag and the counter output changes from a large value to a small value. For example, truck T12
When the conversion code output 3 corresponding to the track T19 is obtained after the conversion code output (15-3 = 12) corresponding to is obtained, the change in the track group is caused by the decrease of the conversion code output from 12 to 3. know. In the second track group adjacent to the first track group consisting of the tracks T0 to T15, the only track whose conversion code output is 3 is T19. Therefore, the microcomputer 27 immediately determines that the head 5 has crossed the track T19. I can know.

In this way, the track recognition code is obtained in the track T42 near the target track T46, and when the microcomputer 27 determines that the remaining head movement amount is T46-T42 = 4, seek data for moving the head 5 at a low speed is obtained. 45
Occurs, the number of times the head 5 reads the track recognition code in the same track group increases, and the target track T46
It is also possible to detect the track recognition code of. When the head 5 goes over the target track T46, the seek direction is of course reversed and the head 5 is returned to the target track T46.

Although the case where the start track is T0 and the target track is T46 has been described above, the same operation is performed when the start track and the target track are arbitrary tracks.

This embodiment has the following advantages.

(1) Since the magnetized regions 12 to 18 are regularly arranged as shown in the range of the tracks T0 to T7 in FIG. 3, a read error in the magnetized region (magnetization reversal) hardly occurs. Further, even if a reading error occurs in the magnetization region (magnetization reversal), the error can be suppressed to a small value (for example, within one track).

(2) Since the tracks are divided into tracks, the length (bit number) of the track recognition code can be shortened and high-speed reading can be performed. That is, reading by oblique scanning as shown in FIG. 8 is also possible.

(3) T0 to T15 tracks are grouped in the front half of T0 to T7 and T8 to T
Magnetized area 11 for distinguishing this by dividing it into the latter half of 15
Since the 16 tracks are provided, the 16 tracks can be distinguished by the eight magnetized regions 11 to 18. Further, 16 tracks can be discriminated by a total of 4 bits of 1 bit of the flag and 3 bits of the output of the counter 26.

(4) Since the conversion code output can be obtained as shown in FIG. 9, the identification of the track group can be easily achieved.

(5) Since new seek data (seek velocity data) is formed each time a track recognition code is detected during seek, the head 5 can be moved to the target track at an optimum velocity.

(6) Compared with the encoder method, an expensive encoder is unnecessary, so that the cost can be reduced.

(7) Compared with the servo surface servo method, a dedicated servo surface is not required, so that the disk usage efficiency is improved.
Further, an expensive servo surface forming device (recording device) is not required.

(8) The seek time can be shortened compared to the method using the step motor.

[Modification] The present invention is not limited to the above-described embodiments, and the following modifications are possible, for example.

(1) A DC motor may be used instead of the voice coil motor 7.

(2) A code for distinguishing the groups may be written in each track group, and the code may be detected by the head 5 to identify the groups.

(3) Instead of writing the track zero detection signals Z1 and Z2,
The stopper 58 may be provided with a track zero detection switch, and the track zero T0 may be detected based on the switch.

[Brief description of drawings]

FIG. 1 is a block diagram showing a magnetic disk drive according to an embodiment of the present invention, FIG. 2 is an expanded view showing a part of the track of the disk of FIG. 1, and FIG. 3 is a servo sector of FIG. Partial view, FIG. 4 is a block diagram showing the control circuit of FIG. 1, FIG. 5 is a block diagram showing the position signal forming circuit of FIG. 1, and FIG. 6 shows the state of each part of FIG. FIG. 7 is a waveform diagram showing the relationship between changes in the head position and position signals, FIG. 8 is a diagram showing the trajectory of the head during seek, and FIG. 9 is a relationship between the track and the conversion code output. FIG. 1 ... disk, 5 ... head, 7 ... voice coil motor, 8 ... track, 9 ... servo sector, 11, 12,
13, 14, 15, 16, 17, 18 ... Magnetized area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Yasuda 3-7-3 Nakamachi, Musashino City, Tokyo Teac Co., Ltd. (56) References JP-A-59-165279 (JP, A) JP-A-58 -218079 (JP, A) JP-A-54-80719 (JP, A)

Claims (1)

[Claims] 1. A recording medium magnetic disk having a plurality of tracks, rotating means for the disk, a head for converting a signal in relation to the disk, and a head for moving the head in a radial direction of the disk. In the magnetic disk device having a moving means, the plurality of tracks are divided into a plurality of groups, and the plurality of groups have at least first, second, third and fourth tracks, respectively. Magnetized regions are respectively provided at first and second angular positions of the first track for recognizing a track, and the first and second magnetic fields of the second track for recognizing the second track. Magnetized areas are provided at the respective angular positions, and a magnetized area is also provided at the third angular position, so that the third track is recognized in order to recognize the third track. Magnetized regions are respectively provided at the second and third angular positions of the magnetic field, and magnetic regions are provided at the second angular position for recognizing the fourth track. The magnetic disk device is characterized in that the angular positions of 3 are determined so as to be adjacent to each other in this order.