JPS6032171A - Tracking device for rotary magnetic recording medium - Google Patents

Abstract

PURPOSE:To attain a head access at a high speed and with high accuracy by having an overrun of a head deyond a desired track, reading a relative position error out of a memory by a reproduction to give an access to another memory and deciding a head reversing pulse. CONSTITUTION:A pulse having the width which overruns a target track is applied to a DC motor from a head shift control circuit 202 in response to a track selection control circuit 200 of a CPU. Then a head is moved. At the same time, a timer 204 is turned on from the rise of said pulse and the lapse time is measured up to a time point when the reproduction signal envelope obtained by a peak position detecting circuit 206 is maximum. Base on this lapse time, an overrun relative position error cuased by the inertia, etc. is read out of a head position curve of an ROM156. Using this position error as an address, an access is given to a head shift amount curve of the ROM156. Thus the head reversing pulse width is decided. This ensures a head access at a high speed and with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION 11 Beans I The present invention relates to a rotating magnetic recording body tracking device, particularly a rotating magnetic recording body that performs tracking when reproducing information recorded on a rotating magnetic recording body such as a magnetic disk or a magnetic drum. The present invention relates to a tracking device. In particular, the present invention relates to a rotating magnetic recording body tracking device that reproduces information recorded on concentric tracks formed on a magnetic disk while applying tracking servo.

11.Recently, it has become possible to use a combination of an imaging device such as a solid-state image sensor or an image pickup tube, and a recording device that uses a magnetic disk, which is inexpensive and has a relatively large storage capacity, as a recording medium to photograph and rotate a subject purely electronically. An electronic still camera system was developed in which images are recorded on a disc and reproduced using a separate television system or printer, and in the future, this system will replace conventional cameras that use chemically processed silver halide photographic film. It is attracting attention as a thing.

However, recording media used for such magnetic recording, especially magnetic disks, are prone to tracking defects due to anisotropy, eccentricity, thermal expansion, etc. There is a problem with scanning the tracks and creating crosstalk.

In order to avoid this problem, there is a method in which tracking servo is applied when recording information to record a tracking signal, and this tracking signal is used to apply tracking servo during reproduction. However, it is not practical to provide a tracking servo mechanism that requires precise control to a small, lightweight recording device such as a camera.

Therefore, one method is to adopt the guard band method or FM azimuth method as the recording method, and to prevent some tracking failures during playback, to prevent the playback head from scanning the adjacent track, or to prevent the signal from the adjacent track even if it scans. There is a way to compensate by not picking it up.

Along with this, a so-called mountain climbing method is also used.

During recording, the recording head is moved at a predetermined track pitch by a stepping motor without applying a tracking servo, and during playback, the envelope of the output signal of each track is detected and the optimal track is identified from the peak position. This applies tracking servo.

Here, a simplified model for tracking will be briefly explained.

FIG. 1 shows a guard band recording system having a guard band width approximately equal to the track width. The same figure (A
) indicates the track where the signal is recorded,
The scanning order is represented by symbols 1, 2, and 3. For example, when scanning the second track, the widthwise center of the magnetic head l is at positions A, B, C, and D.

When the magnetic head 1 is located at position E, the envelope of the reproduction output of the magnetic head 1 at each position takes the form as shown in (B). In other words, when the center position of the magnetic head l is at A and E, the output is O, and at B and D, the output is 50.
At C, which is the normal position, it is 100%.

FIG. 2 shows the FM azimuth recording method. The direction of diagonal lines in FIG. 2A indicates the azimuth direction, and the numbers 0 to 4 indicate the scanning order. For example, when scanning the second track, the widthwise center of the magnetic head l is at positions A, B, C,
When the magnetic head 1 is located at the mouth, E, the envelope of the reproduction output of the magnetic head 1 at each position takes the form shown in FIG. 1B, which is the same as in FIG.

In FIG. 3, the width Tl of the reproducing magnetic head l is narrower than the width T2 of the recorded track, and pilot signals of different frequencies are multiplexed and recorded between adjacent tracks, and tracking is performed based on this pilot signal. Reference numerals 1.2.3 indicate the case of performing servo, and indicate the track scanning order. For example, when scanning the second track, the widthwise center of the magnetic head 1 is at position 2.2.3. ^, B, C, Il
, E, F, the magnetic head l at each position
The envelope of the pilot signal takes the form shown in (B). More specifically, when the gradient center position of the magnetic helad l is at Z and F, the output related to the second track is 0, at A and E it is 50 gears, and at the three positions B, C and D it is 100 gears. %.

However, in such a tracking method, when the playback head deviates from the optimum track, the signal level only decreases no matter which direction the playback head deviates from, and the direction of the deviation cannot be identified. In other words, the direction in which the head should be moved to correct the misalignment is not indicated.
In order to identify the moving direction of the head, it is necessary to detect not only the amount of deviation but also the direction of change, that is, the differential thereof, which requires time for control and is not suitable for high-speed access.

Furthermore, the magnitude of the reproduction signal level also changes depending on the orientation of the magnetic material of the magnetic recording medium, the contact of the reproduction head with the recording surface, and the like. Therefore, for example, once the maximum and minimum values of the envelope at the same scanning position are stored,
As a result, the optimal track position cannot be detected until the influence of the level fluctuation of the reproduced signal is removed.

To summarize, in the above-mentioned hill climbing method, even if a decrease in the peak value of the envelope of the output signal is detected, the direction of the displacement of the head cannot be uniquely determined.

Furthermore, the absolute value of the envelope itself fluctuates due to various factors and is not fixed. Therefore, in order to perform tracking servo in this method, the optimum track position must be determined by minutely changing the head position. Not inherently suitable for high-speed access.

In particular, in the case of magnetic recording media on which images are recorded, fast responsiveness is required. In the case of data processing, the processing time during tracking can be allocated to the execution of other jobs and the operator can wait, but in the case of video systems such as the electronic still camera system mentioned above, This may cause discomfort to viewers, such as distorted playback images or no images being displayed. Such discomfort occurs not only when recording video signals but also when recording audio signals. Also, in terms of high-speed access, a method that records tracking signals during recording is superior, but in the case of cameras that require excellent portability, this method is not recommended due to the requirements for small size and light weight. Since it is difficult to equip a camera with a tracking servo mechanism, there is a strong demand for high-speed access without performing tracking servo during recording.

In servo tracking performed by controlling the pulse width of a DC motor, the head can be moved by a desired amount by changing the pulse width.

Therefore, although this method can be very effectively applied to tracking a recording medium that rotates once, it cannot be directly applied to electronic still cameras that require high-speed tracking servo.

Electronic still cameras require the following high-speed tracking control.

A magnetic disk, for example, has a speed of 3.5 mm per minute. It is rotating with eoo rotation. Therefore, for example, the period of one rotation (1/
If you try to move the magnetic head from one track to a desired track within 80 seconds (or approximately 16.7 milliseconds), the movement time will be within 15 milliseconds, and correction of the head position using the tracking servo will result in an error. Although it depends on the amount, high-speed access of about 1.5 milliseconds is required, for example. Therefore, for example, if the track pitch is 100
gm, that is, the track width is about 50 to 80 #L, and the girt band width is about 50 to 40 #LI+, and 50 tracks are formed on a magnetic disk using a 2 field/1 frame interlacing method to produce 1 track/1 field. When recording a video signal of 2,000 g, the head must move for 2 tracks in one track seek, that is, the head must move by about 200 g within the above-mentioned time. In addition, in the case of l track 1 frame recording, this is 100
It is about the same level as p-en, and the same is true for field stills.

In order to move the head for 50 tracks, that is, about 5 cm, in a high-speed random access of about 1 second, one rotation of the head movement motor requires about the width of the lo track of the magnetic disk. It is necessary to set the gear composition ratio such that the head can be moved.

In other words, in order to satisfy both the requirements of full movement, which searches all tracks at high speed, and fine movement, which accurately tracks the optimal track position, it is necessary to use the inertial operating area of the drive motor for fine movement. do not have. - By the way, when controlling the pulse width of the DC motor for moving the head to move the head 12 degrees to the magnetic field, the amount of head movement is:
It depends on the load torque on the drive mechanism such as the motor shaft and head drive device, and the mechanical time constant due to the inertia of the motor and load.

Specifically, as shown in FIG. 4, the speed response of the DC motor becomes better as the load torque becomes smaller. That is, when the load torque is small, it takes the curve lO and rapidly reaches the steady state of the rotation speed Ma1, and when it becomes large, it takes the curve 12 and slowly reaches the steady state of the speed Ma2, which is lower than the speed Ma1. Therefore, even if drive pulses of the same width are applied to the DC motor, the amount of movement of the head varies depending on the magnitude of the load torque.

Variations in the load torque are caused by, for example, eccentricity of the motor shaft or head drive mechanism (eg, lead screw, etc.). For example, as shown by a curve 14 in FIG. 5, the load changes periodically in synchronization with one rotation R of the head drive mechanism.

Therefore, as described above, if the head is moved by, for example, 10 track pitches in one revolution of the head moving motor, the load will vary considerably even if the head is moved by 1 track pitch S.

Therefore, in order to perform precise servo tracking, it is necessary to take into account such fluctuations in load torque. For example, in the example above, when moving the head accurately to the adjacent track, first, it is necessary to roughly correspond to this amount of movement. The head is roughly moved by applying a pulse width of .', the actual amount of movement is detected, and a pulse is applied to correct this to the desired head position, and this operation is repeated multiple times. is necessary.

However, the influence of the mechanical time constant due to inertia arises because the head moving motor, which is configured to be suitable for high-speed full drive, is finely driven for tracking as described above. To explain in detail, when such a motor is driven by applying a minute pulse (for the motor) with a pulse width of about 15 to 1.5 milliseconds, this is not driving the motor in its steady state, but rather the inertial movement of the motor. This is driving in a region, that is, a transient state. When a magnetic head is driven by a DC motor, when the moving distance of the head is plotted with respect to the time during which the motor is energized, it generally takes a curve 1B as shown in FIG. 6, for example. The rising portion is the transient region, that is, the inertial region. The inertial operating range of the motor is, for example, about 5 to 20 milliseconds, and at most about 100 milliseconds. However, a DC motor with a small time constant and high-speed response has not yet been realized.

This moment of inertia does not vary, unlike the case of load torque. However, since the head movement distance does not change linearly, that is, in proportion to the width of the applied pulse, even if the actual head movement distance for a certain pulse width is known, the desired movement to be tracked cannot be It is not possible to determine the pulse width with respect to the amount simply by a proportional relationship.

In summary, even if pulses of the same pulse width are applied, the amount of movement of the magnetic head varies depending on the load torque. Also,
Since the tracking servo uses the inertial operating range of the motor, it cannot use the operating range where the drive pulse width and the head movement distance are in a proportional relationship; that is, the normal position of the desired target track from the track where the bed is currently located Distance to and pulse width P! The pulse width PE of the correction pulse to be applied in order to correct the error E with the moving distance X of the head moved by applying the pulse of
/X) There is no linear relationship with respect to the quantity PK.

In view of the shortcomings of the prior art, it is an object of the present invention to provide a rotating magnetic recording body tracking device that can access a desired track at high speed during reproduction.

Another object of the present invention is to provide a rotating magnetic recording body tracking device which, particularly when applied to an electronic still camera system, can reproduce images without performing tracking servo during image recording and with high-speed access during playback. It is about providing.

Therefore, in the above-mentioned hill-climbing tracking servo, when moving the head from one track to another adjacent track, the present inventors first determined that when moving the head from one track to another adjacent track, We propose to determine the amount and direction of movement to perform tracking servo by moving the head by the same amount, and then to perform the movement for tracking servo.

According to the present invention, there is provided a magnetic head that reads signals from a plurality of tracks formed on a rotating magnetic recording body with a trajectory in which the relative positions of the recording start and end coincide with each other, and a DC motor. In a rotating magnetic recording body tracking device including a head moving means for moving a magnetic head to a desired track position and a control means for controlling the head moving means to perform tracking servo, the head moving means drives a DC motor with a pulse width. death.

The control means includes a track position detection means that detects the optimum track position from the signal read by the magnetic head, and a DC motor that drives the DC motor with drive pulses with a pulse width sufficient to move the magnetic head beyond adjacent tracks. The control means includes a first memory means for storing the relative head position when the head is moved, and a second memory means for storing the width of the drive pulse of the DC motor with respect to the relative movement amount of the magnetic head. Control means to move AI across adjacent tracks
the magnetic head is moved, the track position detection means identifies the optimum track position from the signal read by the magnetic head, the error in the position of the magnetic head with respect to the identified optimum track position is determined from the first memory means, and the second In this specification, [ For example, in a magnetic disk, a track in which a large number of tracks are formed in a trajectory such that the relative positions of the recording start and end coincide with each other is a track in which a large number of tracks are formed concentrically around a rotation axis, or, In a magnetic drum, a large number of tracks are formed in parallel in the circumferential direction, and one revolution can be made without changing the relative position of the recording head with respect to the magnetic recording medium. A rotating magnetic recording medium tracking device according to the present invention will be explained in detail with reference to the following.

Referring to FIG. 7A, when a drive pulse with a pulse width PO to P4 is applied to the DC motor for moving the head, the change in the position of the magnetic head with respect to the start point of the movement of the magnetic head is the progress from the rise of the drive pulse. Plotted over time. However, the head position is the final amount of head movement when a pulse with a certain pulse width PO is applied! It is shown normalized by 0. In FIG. 7B, the final movement amount of the head normalized in this way is expressed as the driving pulse intensity PO~P.
A curve 20 plotted for 4 is shown.

As we will see, when driving pulses with the same pulse width are applied, the amount of head movement varies depending on the load torque, but when the variation due to the load torque is normalized,
In other words, the amount of movement! The inventors have found that the amount of relative movement with respect to 0 is uniquely determined by the pulse width. This is because it is thought that the pulse PE for correcting the position error is given under almost the same load torque condition as the pulse PO given first, and the curve peculiar to the head moving mechanism such as a motor, that is, the inertia region. This is because it is considered to be used. Therefore, if normalized, they will take the same trajectory. In other words, there is a difference between the positional error XE caused by first applying a pulse with a pulse width PO to move the head and the track pitch TP, and the drive pulse width PE necessary to correct this error XE. The following relationship always holds true: XE/(TP-XE)=PE/PG.

Therefore, when a certain magnetic head drive system is given, and if the curve 20 of the final head movement against the drive pulse width is known, tracking can be performed as follows. In addition.

Although the curve 20 is shown and plotted for five different pulse widths in FIG. 7B, this is merely an example; in reality, it would be more advantageous to plot the curve 20 for a larger number of pulse widths. be.

As shown in Figure 8, first track TI (center position)
Assume that the head located at the position moves beyond the track T2 by an amount equal to or greater than the track pitch TP in response to the drive pulse @PO. By detecting, for example, an envelope 30 of a signal reproduced from the head as the head moves, the normal track position T2 can be identified from its peak position 32. Therefore, if the head position curve 34 for the drive pulse PO shown in FIG. 7A is known, the relative error E between the normal track position T2 and the position of the head H when the head stops moving after finishing movement can be calculated from this. (Dotted line 2
4). As shown in FIG. 8, this corresponds to the head error XE (assuming the direction of head movement as positive) with respect to the normal track position 2, normalized by a value of zero. Therefore, a curve 20 of the relative movement amount of the head with respect to the drive pulse width
Then, the pulse width PE necessary to correct the relative error E is determined (curve line 22), and the motor is rotated in the opposite direction to return the head H to the normal track position T2.

To summarize, in advance, the curve 34 in Figure 7A and the small convex value of Yari Waro M 0b 纂+Gika Mobutsu Hakama 1 Iro /
First, a drive pulse PO having a pulse width sufficient to cross the target track T2 is applied to the DC motor to move the head, and a peak position 32 corresponding to the normal track position is detected. Next, the error E is calculated from this peak position 32 using the data of the curve 34. Therefore, using the curve 20, a pulse @PE for correcting the error E is determined, and the head H is moved in the opposite direction to return to the normal track position T2.

Referring to FIG. 9, the rotating magnetic recording body tracking device f according to the present invention includes a track 10 formed on a rotating magnetic recording body 100 such as a magnetic disk or a magnetic drum.
2, a magnetic head or transducer 104 for recording or reproducing information signals, such as video signals, for example;
is supported by the support arm 10B of the head support lo6.

The support 10B is provided with two holes 110 and 112 in this embodiment. A long guide member 114 passes through the other side 110, and the guide member 114 is connected to the disk 1.
The other hole 112 is arranged parallel to the recording surface of 00 and slides with the hole 110 to hold the support 10B parallel to the recording surface. engage with.

The lead screw 11B is also arranged parallel to the recording surface of the disk 100, and is mechanically coupled to the output shaft of the tracking motor 11B. When the motor 11B rotates in the forward or reverse direction, the head 104 is moved parallel to the recording surface of the magnetic disk 100, that is, in the direction of the arrow Q, and the desired track +02 can be selected.

The reproduction output 120 of the magnetic head 104 is supplied to a reproduction amplifier 122.
It is connected to the detection circuit 12111 through. In this embodiment, the detection circuit 12fl is an envelope detection circuit that detects the envelope of the reproduced signal from the track 102. The detection output 12B is sent to the sample-and-hold circuit (S/H) via a contact or gate 134 that opens and closes with the pulse generated by the sample-and-hold pulse generator 130.
13B, respectively. The sample/hold circuit 136 is a circuit that samples and holds the envelope of the reproduced signal from the track 102 at an appropriate timing. This may be any timing at which sufficient resolution can be obtained in envelope peak detection as described later. Note that the output 124 of the regenerative amplifier 122 is also connected to a reproduced signal output terminal 125, and the reproduced signal is used for the purpose of reproducing, for example, video.

Output 140 of sample reference Hall 1 circuit 13B is connected to system bus 152 of computer system 150 via analog-to-digital converter (ADO) 144. As a result, the reproduced signal from the magnetic head 104 is input to the computer system 150 in the form of a digital signal by the 80O144.

Computer system 150 has a central processing unit t (cpu) +54 to system bus 152 as shown.
A ROM 15B and a RAM 15B are connected and constituted by, for example, a microcomputer.

A motor drive circuit 160 is connected to the bus 152, and its normal rotation (F) drive l! 182 and reverse (R) drive line 16
4 is connected to motor 118. The motor 118 is a DC motor, and is driven by drive pulses supplied from the drive circuit 160 to the drive lines 182 and 1f14, and its rotation angle is controlled by the width of this drive pulse.

RO)l 15111 of the computer system 150 includes a spatula V position curve 34 for a drive pulse with a pulse width PO for moving the head 104 beyond the adjacent track T2, and a head movement amount curve 20 (No. 4B) are stored in the form of digital data.

More specifically, ROM 15B mainly has two storage areas (
ROMI and ROM2, FIG.
The locus of the relative position of the head 104 when a drive pulse having a pulse width PO sufficient to move the head 104 is applied to the drive motor 118 is stored in a memory position of an address corresponding to the elapsed time from the rise of the drive pulse. ing. In addition, the other side (2 for RO) contains data on the relative head movement amount and the relative head position error E, that is, the curve 20.
is stored as the smooth PE of the modified pulse.

The curve 34 stored in the RO memory has a pulse width that overruns the position where the envelope of the reproduced signal of the head 104 peaks to an extent exceeding this position, taking into account mechanical variations in the head movement and movement mechanism. It is advantageous to choose a curve of pO. This mechanical variation also includes backlash caused by track seeking. For example, in a system where the mechanical variation is about 15%, an overrun of about 20% can be expected. This overrun may cause the head 104 to enter the area of a further track.

Referring to FIG. 1θ, the tracking control function of CPU 154 is shown in functional blocks. As will be seen, when the track selection control 200 instructs to select the desired track 1G2, the head movement control 200
2, move the head 1 to a position beyond the target track.
Pulse width Dnnzpen, -t4 for transporting 04
tx, #11<11wRI*n'kh-, V+nA is transferred to a position beyond the target track.

At the same time, the head movement control 202 starts the timer 204. The timer 204 is a timer that counts the elapsed time from the rise of the drive pulse of the motor 118, and is activated by the head movement control 202 and stopped by the peak detection function 206. This may be accomplished either by software or hardware.

While the head 104 is being moved, the peak detection function 206 detects the envelope of the reproduced signal described above and detects the peak position 3.
2 is detected, the timer 204 is stopped. At this time, the count value of the timer 204 should correspond to the optimum track position T2.

When the timer 204 stops, the track selection control 200 accesses the ROM 15B using the address corresponding to the count value T2 of the timer 204 at that time, and estimates the relative error E of the head 104 corresponding to the peak position T2 from the curve 34 of ROW 1. (dotted line 20°, track selection control 2
00 accesses the ROM 15B again using the address corresponding to the relative error E obtained in this way, and R'O
A modified pulse width PE corresponding to the relative error E is determined from the curve 20 of M2.

Accordingly, the track selection control 200 causes the head movement control 202 to correct the head position in accordance with the data read from the ROM 15B, that is, the pulse width PE of the correction pulse. The head movement control 202 controls the motor drive circuit 180, and if the motor 11B was driven in the forward direction F during the first OI (run drive), it is driven in the opposite direction B; If so, the motor 118 is driven in the opposite forward direction F. In this way, the head 104 is driven with the width PE of the correction pulse.
is moved in the opposite direction by an amount corresponding to , and can be located at or closest to the optimal track position T2.

Incidentally, although the present invention has been described with respect to an embodiment of the guard band recording method having a guard I width approximately equal to the track width, the present invention is not limited thereto.

For example, there is an FM azimuth recording method that uses azimuth recording without a guard band to avoid crosstalk between tracks, and a wide recording/narrow playback method that records with a wide recording head and reproduces it with a narrow reproducing head. Needless to say, the present invention can be effectively applied to various systems such as a two-head two-track system in which one head records on two tracks.

For example, a method of detecting deviation from the optimum track position by comparing envelopes of reproduced signals by two heads, such as that described in Patent Application (2) dated June 8, 1980, filed by the same applicant and agent as the present application, is applicable. The present invention can also be applied to.

In the two-head two-track system, for example, two fields and one frame are recorded on two adjacent tracks, or one field is recorded on two tracks. Like this 2
When two adjacently arranged heads scan two tracks at the same time, the "adjacent tracks" referred to herein refer to the track on which the same head is located next in the track seek operation, i.e. one track. It shall mean the track to which it is placed.

According to the present invention, by utilizing the property that the ratio of the head position error to the amount of head movement due to pulse width driving takes a curve specific to the head drive system, the head is once moved to the target track. The error is corrected by detecting the target track position, calculating the width of the error correction pulse from the error, and moving the head backwards accordingly. Therefore, errors can be corrected by effectively using the inertial operating area of the head moving motor, and as a whole, a desired track can be accessed at high speed and with high accuracy.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams conceptually showing examples of magnetic recording methods to which the rotating magnetic recording body tracking device according to the present invention can be advantageously applied, and FIGS. 4 to 6 are illustrations of rotating magnetic recording body tracking A graph to explain the characteristics of the head movement mechanism of the device, #? Figures A and 7B are graphs showing the relationship between the head position and drive pulses to explain the principle of the rotating magnetic recording medium tracking device according to the present invention, and Figure 7C is a graph showing the envelope of the reproduced signal from the disk. Corresponding diagrams. FIG. 8 is an explanatory diagram for explaining the present invention in detail, FIG. 9 is a schematic block diagram showing an embodiment of a rotating magnetic recording body tracking device according to the present invention, and FIG. 1θ is a CPU of the device shown in FIG. FIG. 2 is a functional block diagram illustrating a tracking function executed in the . 20, Head movement curve 34, Head position curve 100, Rotating magnetic recording body 102, Rack 104, Magnetic head 118, Tracking motor 12B, Detector 13B, , Sample number hold circuit 154, , , CPU 15B, , , ROM 1flO, , Motor drive circuit Patent applicant Fuji Photo Film Co., Ltd. Figure, horse F Hibikio +fl reply 11-

Claims (1)

[Scope of Claims] 1. A magnetic head that reads signals from a plurality of tracks formed on a rotating magnetic recording body with a trajectory such that the relative positions of the recording start and end coincide with each other, and a DC motor. A rotating magnetic recording body tracking device comprising: a head moving means for moving the magnetic head to a desired track position; and a control means for controlling the head moving means to perform tracking servo. The head moving means drives the DC motor in a pulse width, and the control means includes: a track position detecting means for detecting an optimum track position from a signal read by the magnetic head; and a track position detecting means for detecting an optimum track position from a signal read by the magnetic head; a first memory means for storing a relative head position when the DC motor is driven with a drive pulse having a pulse width sufficient to move the magnetic head; a second memory means for storing the width of the pulse; the control means controls the head moving means to move the magnetic head beyond adjacent tracks; identify the optimum track position from the signal read by the first memory means, calculate the error in the position of the magnetic head with respect to the identified optimum track position from the first memory means, and read the magnetic head according to the determined error from the second memory means. Tracking of a rotating magnetic recording medium, characterized in that the width of a drive pulse of a DC motor is determined with respect to the relative movement amount of the head, and the head moving means is controlled to rotate the motor in a reverse direction according to the determined Norms width. Device. 2. In the tracking device according to claim 1, the relative head position stored in the first memory means is determined based on the elapsed time from the rise of the drive pulse when driving the DC motor with a pulse width. The track position detecting means includes a peak detecting means for detecting a peak of an envelope of a signal read by the magnetic head, and the control means controls the head moving means to move the head across adjacent tracks. timer means for counting the elapsed time from the rise of the drive pulse when moving the magnetic head; A rotating magnetic recording body tracking device characterized in that the optimum track position is determined from a first memory means.