JP3057137B2 - Magnetic recording / reproducing apparatus and head height adjusting method therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for adjusting a relative height between two magnetic head groups mounted on an actuator, and more particularly to a helical scan type video tape, for example. Recorder (VT
R), such as a rotary head type magnetic recording / reproducing apparatus,
The present invention relates to a method and an apparatus for adjusting a relative height between two magnetic head groups during recording.

[0002]

2. Description of the Related Art In recent years, in a magnetic recording / reproducing apparatus, recording density has been remarkably increased, and accordingly, track width has been narrowed. For example, in the LP mode of a home digital VTR, the track pitch is 5 μm.
m. As the track width becomes narrower, conditions required for a magnetic head to perform a good tracking operation are becoming severer. That is, when a signal is reproduced from a narrow track by a conventional magnetic recording / reproducing device fixed to a rotating drum so that the magnetic head cannot move in the track width direction, the influence of the tracking deviation of the magnetic head is affected. Appears remarkably, so that a sufficient reproduction output cannot be obtained from the magnetic head.

As a factor of such a tracking deviation, a so-called track bend generated at the time of recording can be considered. Since this track bend is unique to each magnetic recording / reproducing device, especially when the track is reproduced by a magnetic recording / reproducing device different from the device used for recording, the tracking deviation caused by the track bend is small. The size cannot be ignored.

Therefore, a magnetic head which can be displaced in the track width direction by an actuator such as a piezoelectric element is used.
A dynamic tracking system that detects a relative position error of the head with respect to the track on the magnetic tape based on a signal reproduced from the magnetic head and controls the position of the magnetic head in the track width direction in a closed loop in accordance with the error. A magnetic recording / reproducing device provided with
For example, it is disclosed in U.S. Pat. No. 4,237,399.

As a method for detecting a relative position error signal of a head with respect to a track on a magnetic tape during reproduction, several methods can be considered, and a so-called pilot signal method is often used. In this pilot signal system, a pilot signal of a different frequency is superimposed on a main signal for each track and recorded, and at the time of reproduction, crosstalk components of pilot signals from two adjacent tracks on both sides of a certain track are respectively extracted. By comparing these crosstalk components, the position error amount of the magnetic head and the polarity indicating the direction of the deviation of the magnetic head from the track can be simultaneously detected.

If the magnetic head is used for both recording and reproduction, the cost can be reduced by reducing the number of heads and simplifying the drum structure. However, when the magnetic head is provided on the actuator as described above, the head height during recording cannot be determined. For example, if there is a relative height deviation between two sets of magnetic heads mounted on different actuators, Therefore, it is impossible to form a track having a predetermined track width and a predetermined track pitch. As a result, sufficient reproduction output cannot be obtained for a track with a narrow track width. This effect becomes more pronounced as the track width (track pitch) is smaller.

Therefore, a method for adjusting the relative height of two sets of magnetic heads mounted on different actuators has been proposed, for example, as disclosed in Japanese Patent Application Laid-Open No. 2-44514.

FIG. 37 is a bottom view of a rotary drum showing a head arrangement of a conventional magnetic recording / reproducing apparatus employing such a head height adjusting method. In FIG. 37, magnetic heads 200A and 200B are mounted on actuators 201A and 201B that can be displaced in the track width direction, respectively. On the other hand, FIG. 38 is a schematic diagram illustrating the principle of a conventional head height adjustment method. Hereinafter, a conventional head height adjusting method will be described with reference to FIGS. 37 and 38. FIG.

First, the magnetic tape 202 is stopped. In this state, the recording track 200a is formed in the first half of the scan on the magnetic tape 202 by the magnetic head 200A. Next, in the first half of scanning of the same track on the magnetic tape 202 by the magnetic head 200B, the same recording track 200a is reproduced. At this time, the magnetic head 2
00B follows the recording track 200a so that the actuator 201B on which the magnetic head 200B is mounted.
Is displaced, and from the displacement amount at this time, the track deviation amount, that is, the magnetic head 2 with respect to the magnetic head 200A is
A height shift amount of 00B is obtained. Next, the magnetic head 2
In the latter half of the scanning of the magnetic tape 202 by 00B, a recording track 200b is formed. Next, the same track on the magnetic tape 202 is scanned again by the magnetic head 200A. In the latter half of this scan, the recording track 200
b is reproduced by the magnetic head 200A, and similarly, the track deviation amount at this time, that is, the height deviation amount of the magnetic head 200A with respect to the magnetic head 200B is obtained.

Therefore, if the average of these two height deviations is determined and one of the magnetic heads is displaced in accordance with the value, the relative height between the magnetic heads 200A and 200B becomes zero, and the signal height is reduced. At the time of recording, a track having an accurate track width and an accurate track pitch can be formed.

[0011]

However, the conventional head height adjusting method as described above has the following problems. That is, since the detection of the relative height deviation amount between the heads is performed based on only one track, the detection errors are not averaged, and sufficient accuracy cannot be obtained.

Further, since the magnetic tape is in a running stopped state, the contact between the magnetic tape and the magnetic head tends to be unstable. As a result, it is not possible to discriminate whether the change in the reproduction output is due to a relative height deviation between the heads or a defective hit.

Furthermore, since the magnetic tape is in a running stop state, the position of the magnetic tape in the width direction and the longitudinal direction is likely to be unstable. As a result, there is a problem that the position of the reference track changes, and the detection accuracy of the relative height deviation between the heads is poor.

Accordingly, an object of the present invention is to provide a rotary head type magnetic recording / reproducing apparatus using a recording / reproducing head mounted on an actuator, which detects and adjusts a relative height deviation between heads with high accuracy, and performs signal recording. Sometimes to form a track with the correct track width and track pitch.

[0015]

According to the present invention, a rotating drum, two sets of magnetic heads each comprising one or a plurality of magnetic heads, and two sets of magnetic heads attached to the rotating drum are respectively tracked. In a rotary head type magnetic recording / reproducing apparatus provided with a pair of actuators displaced in the width direction, a relative height between two sets of magnetic heads is adjusted, and any one of the two sets of magnetic heads is used. By at least one magnetic head constituting the magnetic head group of
A step of cyclically recording a plurality of types of signals predetermined for each track on a running magnetic tape in a predetermined order to form a plurality of tracks, and a step of rewinding the magnetic tape after recording the signals. A signal from two tracks of a plurality of tracks separated by a distance twice as long as a track pitch during normal signal recording by at least one magnetic head constituting one of the two magnetic head groups; Controlling the running of the magnetic tape so that the magnetic tape is reproduced evenly, and at least one magnetic head constituting the other of the two magnetic head groups in the height adjustment mode in which the running of the magnetic tape is controlled. Detecting information on the relative height between the two magnetic head groups from the output obtained by reproducing the signal according to the above, and two sets based on the detected information. And a step of adjusting the relative height between the magnetic head group.

According to another aspect of the present invention, a rotating drum includes a rotating drum, a pair of magnetic heads, and a pair of actuators attached to the rotating drum for respectively displacing the pair of magnetic heads in the track width direction. In a head type magnetic recording / reproducing apparatus, a method of adjusting a relative height between a pair of magnetic heads is such that one of the pair of magnetic heads travels a plurality of types of signals predetermined for each track. Forming a plurality of tracks by recording cyclically in a predetermined order on a magnetic tape; rewinding the magnetic tape after recording a signal; and a gap between the plurality of tracks by the other of the pair of magnetic heads. Controlling the running of the magnetic tape so that signals from two tracks adjacent to each other are evenly reproduced; In the adjustment mode, leave the offset signal corresponding to a displacement of the actuator in advance prepares a plurality
Detecting the output level of a signal reproduced from one magnetic head while sequentially applying the offset signals to one of the pair of actuators corresponding to one magnetic head and displacing one magnetic head; Detecting an offset signal when the output level of the reproduced signal becomes the maximum as information relating to the relative height between the pair of magnetic heads, and detecting the offset signal based on the detected information. Adjusting the relative height between them.

According to still another aspect of the present invention, a rotating drum, two magnetic head groups each including n (n is an integer of 2 or more) magnetic heads, and two sets of magnetic heads attached to the rotating drum are provided. In a rotary head type magnetic recording / reproducing apparatus having a pair of actuators for displacing a magnetic head group in a track width direction, a method of adjusting a relative height between two magnetic head groups is performed by adjusting the relative height. Sometimes, the rotational speed of the rotating drum is k (k
Is a multiple of n other than 1) times, or the running speed of the magnetic tape is 1 / k of the running speed during normal recording / reproducing.
And setting at least one of the two sets of magnetic heads to at least one of the magnetic head groups to convert a plurality of signals predetermined for each track to the set rotation of the rotating drum. Forming a plurality of tracks by recording in a predetermined order cyclically on the running magnetic tape at a number or at a set running speed of the magnetic tape, and rewinding the magnetic tape after recording the signal Steps and two tracks of a plurality of tracks separated by a distance twice as long as the track pitch during normal signal recording by at least one magnetic head constituting one of the two magnetic head groups Controlling the running of the magnetic tape so that the signal is reproduced evenly from the magnetic tape, and a height adjusting mode in which the running of the magnetic tape is controlled. Of a signal reproduced from two tracks of a plurality of tracks separated by a distance twice as long as the track pitch during normal signal recording by at least one magnetic head constituting the other magnetic head group of the drive group Detecting information on the relative height between the two magnetic head groups based on the level difference or the output level of a signal reproduced from a track scanned by the head;
Adjusting the relative height between the two magnetic head groups based on the detected information.

According to still another aspect of the present invention, a rotary head type magnetic recording / reproducing apparatus comprises: a test surface provided in each of two magnetic head groups; and at least one detecting device for detecting a height of the test surface. A sensor for storing the output of the sensor for each of the test surfaces at the completion of the step of adjusting the relative height between the two magnetic head groups; Independently controlling the pair of actuators so that the output of the sensor detected for each of the test surfaces during recording matches the stored sensor output.

According to still another aspect of the present invention, the relative height adjusting method stores the output of the sensor for each of the test surfaces at the completion of the step of adjusting the relative height between the two magnetic head groups. And when the magnetic head group provided with the test surface is displaced from each of the test surfaces by an integral multiple of the track pitch during normal signal recording from the state where the relative height adjustment is completed. A step of storing the output of the sensor and, based on the sensor output stored for each of the test surfaces, for each of the test surfaces, a sensor based on the height at the time when the relative height adjustment is completed. Calibrating the displacement-output curve, and, at the time of normal signal recording, the sensor output detected for each of the test surfaces is calculated based on the displacement-output curve calibrated for each of the test surfaces. ,It Converting the relative height of the two magnetic head groups into a displacement based on the height at the time when the relative height adjustment is completed; The method further includes a step of calculating as a shift and a step of correcting an optimum offset signal applied to at least one of the actuators based on the calculated difference.

According to still another aspect of the present invention, the relative height adjusting method includes a method for adjusting a relative height between two magnetic head groups for each of the plurality of magnetic head groups. Storing the output of the sensor for each of the surfaces, and for each magnetic head group,
Calibrating a displacement-output curve of the sensor based on the stored sensor output based on the height at the time of completion of the relative height adjustment for one of the test surfaces; When a regular signal is recorded, the sensor output detected for one of the test surfaces is converted into a displacement amount based on the height at the time when the relative height adjustment is completed based on the calibrated displacement-output curve. Converting, and calculating the difference between the detected displacement amounts of the two magnetic head groups as a relative height deviation over time of the two magnetic head groups, based on the calculated difference. Correcting the optimum offset signal applied to at least one of the actuators.

According to still another aspect of the present invention, a rotary head type magnetic recording / reproducing apparatus includes a first reference surface provided on a bottom surface of a rotating drum, and a first reference surface provided on a bottom surface of the rotating drum. And one or more second reference planes provided at a predetermined height apart from each other, and the relative height adjustment method includes:
Detecting the output of the sensor for each of the first and second reference planes; and calibrating a distance-output curve of the sensor based on the height of the first reference plane based on the detected sensor output. And converting the stored sensor output for each of the test surfaces into a distance from the first reference surface based on the calibrated distance-output curve, and calculating the difference between the two. Storing the difference in the distance at the time of completing the step of adjusting the relative height between the magnetic head groups of the set, and the difference in the distance detected at the time of recording the normal signal as the difference in the distance at the completion of the adjusting step. Controlling the pair of actuators to coincide with each other.

According to still another aspect of the present invention, a rotary head type magnetic recording / reproducing apparatus capable of adjusting a relative height between a pair of magnetic heads comprises a rotary drum, a pair of magnetic heads, and a rotary drum. A pair of actuators respectively attached to the actuator and displacing the pair of magnetic heads in the track width direction;
Means for forming a plurality of tracks by cyclically recording a plurality of types of signals predetermined for each track on a running magnetic tape in a predetermined order by one of a pair of magnetic heads; Means for rewinding the magnetic tape after recording, and running the magnetic tape so that signals from two adjacent tracks of the plurality of tracks are evenly reproduced by the other of the pair of magnetic heads. A plurality of offset signals corresponding to the displacements of the actuators are prepared in advance in the height adjustment mode in which the magnetic tape is controlled to travel, and the offset signals are supplied to one of the magnetic heads of the pair of actuators. While displacing one magnetic head by sequentially applying to the corresponding ones,
Means for detecting the output level of a signal reproduced from one of the magnetic heads, and an offset signal when the output level of the reproduced signal is maximized as information relating to the relative height between the pair of magnetic heads. Means for detecting, from an offset signal as information relating to the relative height, an optimum offset signal to be applied to at least one of the pair of actuators in order to adjust the relative height, and means for storing the optimum offset signal; Means for applying the stored optimal offset signal to at least one of the pair of actuator means to adjust the relative height between the heads at the time of signal recording.

According to still another aspect of the present invention, a rotary head type magnetic recording / reproducing apparatus capable of adjusting a relative height between two magnetic head groups includes a rotary drum and n (where n is 2 or more) ), A pair of actuators attached to the rotating drum and displacing the two magnetic head groups in the track width direction, and a pair of rotating heads for adjusting the relative height. The number of revolutions of the drum is set to k times (k is a divisor of n other than 1) times the number of revolutions during normal recording / reproduction, or the traveling speed of the magnetic tape is 1 / k of the traveling speed during regular recording / reproduction. The means for setting the number of times and a plurality of types of signals predetermined for each track by the at least one magnetic head constituting one of the two magnetic head groups are used to set the rotation of the rotating drum. number Means for forming a plurality of tracks or running speed of the set magnetic tape, recorded cyclically in a predetermined order on a magnetic tape running,
Means for rewinding the magnetic tape to the signal recording portion, and at least one of the two magnetic head groups constituting one of the magnetic head groups
Means for controlling the running of the magnetic tape so that the signals are reproduced evenly from two tracks separated by a distance twice as long as the track pitch at the time of normal signal recording by the two magnetic heads; In a height adjustment mode in which the running of the magnetic tape is controlled, at least one magnetic head constituting the other magnetic head group of the two magnetic head groups has a track pitch of 2 at the time of recording a normal signal among a plurality of tracks. Corresponds to the head when the difference between the output levels of the signals reproduced from the two tracks separated by twice the distance becomes zero or when the output level of the signal reproduced from the track scanned by the head becomes the maximum. Means for detecting the offset signal applied to the actuator to be changed as information relating to the relative height between the two magnetic head groups;
Means for obtaining an optimum offset signal to be applied to at least one of the pair of actuators for adjusting the relative height from the offset signal as information relating to the relative height, and storing the optimum offset signal; Means for applying the adjusted optimum offset signal to at least one of the pair of actuator means to adjust the relative height between the magnetic head groups.

[0024]

According to the present invention, the information on the relative height between the two magnetic head groups is detected while the magnetic tape is running, and the relative height is adjusted. Here, a plurality of tracks serving as a reference for head height adjustment are formed. The magnetic head group sequentially scans the plurality of tracks to detect and adjust the relative height. Therefore, the relative height detection error can be averaged, and the relative height detection error due to poor contact between the magnetic tape and the magnetic head and instability of the magnetic tape position can be reduced. The relative height of the magnetic head group can be adjusted with high precision.

Further, according to the present invention, a sensor for detecting the height of the test surface of the magnetic head group is provided, and the displacement-output curve of the sensor is calibrated. Therefore, even if the sensor has a non-linear characteristic, it is possible to accurately detect and correct the relative height deviation over time of the two magnetic head groups during normal signal recording.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing each embodiment of the present invention, the arrangement of a magnetic head group on a rotating drum, an application example of the present invention, a drum structure equipped with an actuator, a configuration of each magnetic head group, The scanning locus of the magnetic head group on the magnetic tape when the track pattern to be formed, the tape running speed, or the rotation speed of the magnetic head group is changed will be described.

First, the arrangement of the magnetic head group on the rotating drum will be described. FIG. 1 and FIG.
FIG. 3 is a schematic sectional view and a bottom view of the rotating drum 1. The rotating drum 1 rotates in the direction of the arrow in FIG. One or more (n) magnetic head groups AT and BT, respectively
Magnetic heads A ₁ , A ₂ ,..., _An and B ₁ , B ₂ ,.
, B _n (n ≧ 1), and are mounted on the actuators 100A and 100B, respectively. FIG. 2 shows a magnetic head A having two (n = 2) magnetic head groups AT and BT.
₁ shows an example composed of A ₂ and B ₁ and B ₂ .

Next, an example of application of the present invention will be described. In recent years, magnetic recording / reproducing apparatuses have remarkably increased their recording densities.
D-DVTR), home high-definition digital V
TR (hereinafter referred to as HD-DVTR) standard review
Digital VCR Conference ". In order to satisfy the specifications of this council, the number of drum revolutions of the SD-DVTR was 9000.
rpm, the number of heads: 2, the number of drum rotations: 9000 rpm and the number of heads: 4, for the HD-DVTR are recommended.

In the LP mode (long play mode) of the SD-DVTR and HD-DVTR, a track pitch of 5 μm is required. In this case, a dynamic tracking technique is essential. Therefore, in the present invention, when each of the magnetic head groups AT and BT includes one magnetic head A ₁ and B ₁ (n = 1), the present invention is applied to, for example, the LP mode of the SD-DVTR, and the magnetic head groups AT and BT are used. When the BT includes two magnetic heads A ₁ and A ₂ and B ₁ and B ₂ (n = 2), for example, H
Applied to LP mode of D-DVTR.

Next, the actuators 100A, 100B
A specific structure of a drum device equipped with a will be described.

As the actuators 100A and 100B, a bimorph piezoelectric actuator, an electromagnetic moving magnet type actuator, a moving coil type actuator or the like is used. Here, actuator 1
00A and 100B may be independently driven, or may be simultaneously driven by the same drive circuit. The actuator 100
When A and 100B are driven at the same time, those which are displaced in directions opposite to each other are used. For example, FIG.
An actuator having a form as shown in FIGS.

First, the bimorph piezoelectric actuator 10
An example in which 0A and 100B are mounted will be described. In this example,
The actuators 100A and 100B are independently driven by independent drive circuits. FIG. 39 is a bottom view of the rotary drum 1, and FIG. 40 is a cross-sectional view of the drum device 3. Reference numeral 1 denotes a rotating drum, which is a bimorph piezoelectric actuator 100A, 10B.
OB is fixed. A head base 308 on which a magnetic head group AT is mounted is provided at the tip of the actuator 100A.
a, a head base 308b on which a magnetic head group BT is mounted is attached to the tip of the actuator 100B.

Reference numeral 2 denotes a fixed drum to which the stator core 306 of the rotary transformer is fixed. Reference numeral 300 denotes outer bearings 301, 301 fixed to the fixed drum 2.
It is a shaft supported by. The rotating drum 1 is mounted on a disk 307 fixed to the shaft 300 by press fitting or the like, and is rotatably held by the fixed drum 2.
The disk 307 has a rotor core 3 of a rotary transformer.
05 is fixed. 302 is a stator of the motor fixed to the fixed drum 2, and 303 is a collar 3 on the shaft 300.
The rotor of the motor is fixed through the reference numeral 04.

With the above configuration, the motor starter 30
The rotating drum 1 which is substantially integral with the rotor 303 of the motor is rotated by the rotational driving force of the motor with respect to the fixed drum 2 which is substantially integral with the rotating drum 2. Numeral 309 denotes a slip ring fixed to the rotating drum 1, which is in sliding contact with the brush 310. The brush 310 is a chassis (not shown)
Is fixed by an appropriate method.

FIG. 41 is a cross-sectional view of an example of the bimorph piezoelectric actuator 100B.
The piezoelectric ceramics 312 and 312 are laminated with the intermediate electrode 311 interposed therebetween. The electrodes 311, 313 are passed through the slip ring 309 and the brush 310.
By applying a voltage between the piezoelectric ceramics 31
2 and 312 are curved, and the magnetic head group BT is vertically displaced. The same applies to the operation of the piezoelectric actuator 100A.

Next, an example in which the moving magnet type actuators 100A and 100B are mounted will be described. Moving magnet type actuator 100A, 100B
Is composed of a parallel leaf spring mechanism, a magnetic circuit, and a driving coil, which will be described later.
a, 425b. In this example, the actuators 100A and 100B are simultaneously driven by the same drive circuit. The actuators 100A and 100A
B are displaced in directions opposite to each other.

FIG. 42 shows a drum device of this embodiment using motors 418 and 420, a collar 419, a rotating drum 1, head bases 402a and 402b, and magnetic head groups AT and B to be described later.
FIG. 43 is a top view in which T is omitted, and FIG. 43 is a top view in which first leaf spring 405 is further omitted.
4 and FIG. 45 are cross-sectional views along line AA and line BB in FIG. 42, respectively. FIG. 46 shows a parallel leaf spring 407 described later.
It is a perspective view of. Here, an example of the drum device of the fixed shaft type is shown, but the form of the drum device is not limited to this, and a drum device of the shaft rotation type may be used.

First, the components of the present drum device will be described. 414 is a shaft, 415 and 415 are outer bearings, and 416 is a disk. A disk 416 fixed to the outer periphery of the outer bearings 415 and 415 is rotatably held on the shaft 414. Reference numeral 2 denotes a fixed drum. The fixed drum 2 includes a terminal block 423 of a terminal 424 connected to a stator core 421 of the rotary transformer and a winding of the stator core 421, and a permanent magnet 404 described later.
A yoke 410 having an annular concave cross section that forms a magnetic circuit together with a and 404b is fixed. Annular drive coils 409 ', 409 "are fixed to two inner walls 410', 410" of the yoke 410 having the concave cross section, respectively. Reference numeral 412 denotes a terminal provided on the terminal block 411, which is connected to the drive coil 409 'or 409 "
There are four or four.

Reference numeral 1 denotes a rotating drum.
Two fixing members 408, 40 located at positions opposed by 0 °
Ring-shaped first and second leaf springs 40 through 8 '
5,406 are fixed. The first and second leaf springs 405 and 406 constitute a parallel leaf spring 407.
The movable members 425a and 425b are sandwiched between the portions.

The movable member 425a has a two-layer structure including a permanent magnet 404a and a spacer 403a made of a non-magnetic material. Head base 402
a is attached. Here, the permanent magnet 404a is magnetized in the radial direction of its rotation locus. Movable member 425
b, the direction of magnetization of the permanent magnet 404b is the permanent magnet 404a.
And in the opposite direction. Other configurations of the movable member 425b are the same as those of the movable member 425a. 418 and 420 are a rotor and a stator of the motor, respectively. In this example, the fixing members 408 and 408 ′ are fixed to the rotating drum 1, but may be fixed to the disk 416.

Next, a method of assembling the present drum device will be described. After the shaft 414 is fixed to the fixed drum 2 by press-fitting, heat shrinking, or the like, the rotating drum 1 is fixed to a disk 416 rotatable with respect to the shaft 414. In this state, the rotating drum 1 is held rotatably with respect to the fixed drum 2. Next, the rotor 418 of the motor is fixed to the upper surface of the rotating drum 1, and the shaft 414 has a collar 419.
Is fixed. Finally, the motor stator 4 is attached to the collar 419.
20 is fixed. With the above configuration, the rotating drum 1 substantially integral with the rotor 418 of the motor is rotated by the rotational driving force of the motor with respect to the fixed drum 2 substantially integral with the stator 420 of the motor.

Next, the operation of the actuators 100A (movable members 425a) and 100B (425b) will be described.
As described above, the magnetic head group AT is indirectly fixed to the movable member 425a of the parallel leaf spring 407 having the fixed members 408, 408 'fixed to the rotating drum 1 as fixed ends. (Perpendicular to the plane). Further, the permanent magnet 404a constituting the movable member 425a is magnetized in the radial direction of its rotation locus.
Two magnetic poles 404a ', 404a "of the permanent magnet 404a
Are yokes 4 fixed to the fixed drum 2 side, respectively.
10, two walls 410 ', 410 "and a gap 426',
426 "are opposed to each other to form a closed magnetic circuit.

The two walls 410 'of the yoke 410,
Drive coils 409 'and 409 "are fixed to 410", respectively, and the drive coils 409' and 409 "are linked to the magnetic flux passing through the gaps 426 'and 426".

Here, the drive coil 40 is connected through the terminal 412.
When currents in the same direction are supplied to the magnetic poles 9 'and 409 ", the electromagnetic force from the drive coil 409' is applied to the magnetic pole 404a 'of the permanent magnet 404a, and the electromagnetic force from the drive coil 409" is applied to the magnetic pole 404a ". The magnetic poles 404 a ′ and 404 a ″ are acted on by the same direction of electromagnetic force, and the direction of action is up and down. Movable member 425
a, the magnetic head group AT shifts until the electromagnetic force acting on the permanent magnet 404a and the reaction force of the parallel leaf spring 407 are balanced. The operation of the movable member 425b (magnetic head group BT) is the same as described above, but the permanent magnet 404 of the movable member 425b is
Since b is magnetized in the opposite direction to the permanent magnet 404a, it is displaced in the opposite direction to the movable member 425a. Therefore, by applying a current to the drive coils 409 ', 409 ", the magnetic head groups AT, BT are displaced in opposite directions.

Next, the configuration of each magnetic head group when the magnetic head group is composed of a plurality of magnetic heads will be described. The following describes one magnetic head group AT, but the same applies to the other magnetic head group BT. Magnetic heads A ₁ of the magnetic head group _{AT, A 2, ..., A} n , like having a magnetic head respectively adjacent, equal steps and normal signal recording operation of the track pitch Tp (track width Tw), the accuracy at the time of manufacture Well managed and integrated.

The azimuth angles of two adjacent magnetic heads are different from each other. As an example of the configuration of the magnetic head group, FIG. 3 shows a configuration in a case where the magnetic head group AT includes two magnetic heads A ₁ and A ₂ . The width of each magnetic head is Wh, and has the following relationship with the track pitch Tp.

[0047] Tp <Wh <2Tp ... (1 ) where the width of the track a ₁ to the magnetic head A ₁ during signal recording is formed, a predetermined track width Tw as shown in FIG. 4
(= Tp). This is true even if the tape speed or the rotation speed of the magnetic head group changes.

Next, during normal signal recording, the magnetic head group A
A track pattern formed by T and BT will be described.
You. FIG. 5 shows that each of the magnetic head groups AT and BT has n magnetic heads.
The magnetic head group AT and BT
This is a track pattern when the height δ is zero. Naoko
Here, δ is particularly the magnetic head group for the magnetic head group AT.
It shall represent the relative height of the BT. Magnetic head A₁,
A_Two, ..., A_n, B₁, B_Two, ..., B_nFormed by
Track a₁, A_Two, ..., a_n, B₁, B _Two,…,
b_nAre a predetermined track width Tw and a predetermined track
It has a pitch Tp. Note that such guard band
In the data recording, Tw = Tp.

Here, tracks a ₁ -a _n-1 and b ₁ -b
_The reason why the width of _n-1 is the predetermined track width Tw is that a step equal to the track width Tw (track pitch Tp) is provided between adjacent magnetic heads as described with reference to FIGS. It is. The tracks a _n and b _n have the predetermined track width Tw (= Tp) because the tape running speed Vt is set as in the equation (2).

Vt = (nTp / sin θ) / T (2) where θ is the track angle, T is the magnetic head group AT, BT
Is the time required to rotate 180 °. The track angle θ can be expressed as in equation (3), where V _h is the head rotation speed and θ _r is the still angle.

Θ = Tan^-1｛V_h・ Sin θ_r/ (V_h・ Cos θ_r-V_t)｝ ... (3) where V_t= 18.831 mm / sec, V_h= 102
26mm / sec, θ _r= 9.150 °, θ =
It becomes 9.1668 °.

Next, the scanning trajectory of the magnetic head group on the magnetic tape when the tape speed or the rotation speed of the magnetic head group is changed will be described. In each of the above cases, the distance L1 and the track angle θ1 that the magnetic tape moves while the magnetic head groups AT and BT rotate by α °.
Can be expressed as follows from the above equations (2) and (3).

[0053] (i) when the tape speed to 1 / n ₁ times the velocity V _t during normal recording and _{reproduction: L1 = V t / n 1} · (α / 180) T = {(n / n 1) (Tp / sin θ)｝ · (α / 180) (4) θ1 = Tan ^-1 {V _h · sin θ _r / (V _h · cos θ _r -V _t / n ₁ )} (5) (ii) If the rotational speed of the magnetic head group and n ₁ times the velocity V _h during normal recording (magnetic head group aT, B
When the time required for T to rotate by 180 ° is 1 / n ₁ times the time T for normal recording / reproducing): L 1 = V _t · (α / 180) · (T / n ₁ ) = ｛ (N / n ₁ ) · (Tp / sin θ)｝ · (α / 180) (6) θ ¹ = Tan ⁻¹ ｛n ₁ · V _h · sin θ _r / (n ₁ · V _h · cos θ _r -V _t )｝ (7) From the above equations (4) to (7), in any of the above cases,
Since the locus of the magnetic head group on the magnetic tape is the same,
In the following, they are not particularly distinguished.

Also, V_t= 18.831 mm / sec,
V_h= 10226 mm / sec, θ _r= 9.150 °
Then V_h・ Cos θ_rIs V_tMuch larger than
Therefore, the following equation holds.

Sin θ1 ≒ sin θ (8) Therefore, the expressions (4) and (6) are as follows.

L1 = {(n / n ₁ ) · (Tp / sin θ1)} · (α / 180) (9) Therefore, the magnetic head groups AT and BT are 180 ° and 36 °.
During the rotation by 0 °, the distance L1 (1
80 °) and L1 (360 °) can be expressed as follows.

L1 (180 °) = (n / n ₁ ) · (Tp / sin θ1) (10) L1 (360 °) = 2 (n / n ₁ ) · (Tp / sin θ1) (11) From equations (10) and (11), the following equation holds.

L1 (180 °) · sin θ1 = (n / n ₁ ) · Tp (12) L1 (360 °) · sin θ1 = 2 (n / n ₁ ) · Tp (13) Each embodiment will be described.

First, a first embodiment of the present invention will be described with reference to the flowchart of FIG. In the first embodiment, the magnetic head groups AT and BT are each composed of one magnetic head A ₁ and B ₁ .

(I) First, using one of the pair of rotating magnetic heads A ₁ and B ₁ , for example, only the magnetic head B _1, and adjusting the relative height between the magnetic heads A ₁ and B _1. Is recorded on the magnetic tape (step S
1). Actuator 100B having the magnetic head B ₁ at this time is not operated. 7, track b _1, b ₁ are formed on a magnetic tape by the magnetic head B _1,
... is shown. The signals recorded on the tracks b ₁ , b ₁ ,... May be cyclic signals based on a certain rule.

In the example described below, for example, signals f ₁ , f ₂ , f ₁ ,... Of different frequencies are recorded at a level equal to cyclic. Hereinafter, this signal is referred to as a pilot signal. Note that the pilot signal may be recorded while being superimposed on the main signal. The frequency of the pilot signal is set to a low frequency so that it can be reproduced even by magnetic heads having different azimuths. Tracks b ₁ and b
_1, ... each having a width of, equal to the width Wh of the magnetic head, a track pitch, the track pitch T during normal signal recording
p, that is, 2Tp. Here, the aforementioned (1)
From the equation, the following relationship holds.

Wh <2Tp (14) From this relationship, a gap is generated between tracks as shown in FIG. During normal signal recording, the magnetic head A ₁
By truck enters. In that case, the overlap in some areas the track by track and the magnetic head B ₁ by the magnetic head A _1. After the above-mentioned pilot signals f ₁ and f ₂ are alternately recorded for a certain period, the magnetic tape is rewound (step S1), and a reproducing operation for adjusting the relative height is started.

(II) FIG. 8 shows the other magnetic head A ₁
Using, when playing a track b ₁ recorded as described above by the magnetic head B _1, shows the relationship between the track and the head A _1. In this case, actuator 100A having the magnetic head A ₁ is not operated. Magnetic head A ₁ is two times the track pitch Tp (2T
The pilot signals f ₁ and f ₂ are reproduced so as to straddle two tracks b ₁ and b ₁ separated by a distance p). At this time, the pilot signals f ₁ and f ₂ reproduced from each of the tracks b ₁ and b _{1 have} the same level, that is, the tracks on which the pilot signals f ₁ and f ₂ are recorded are evenly traced. Thus, the running of the tape is controlled by, for example, capstan control (step S2).

[0064] Tape running control until achieving the goals described above, multiple magnetic heads A _1, is rotated, is repeated (step S3). Incidentally, while the magnetic head A ₁ scans once a magnetic tape, if Re performed sufficient tape running control is not necessary to repeat the scanning by the head A ₁ described above.

(III) FIG. 9 shows one of the magnetic heads.
De B₁And the pilot signal f ₁, F_TwoIs recorded
Truck b₁, B₁,… When playing
De B ₁And the relationship between the track and the vehicle. At this time,
A₁And head B₁With a relative height δ of zero
Then, just as in state b in FIG.
Head B₁Scanning trajectory matches,
De B₁The playback output from is maximized. Where δ
Is, as described above, particularly the magnetic head A₁Magnetic head
De B₁Represents the relative height of.

[0066] However, if the relative height deviation between heads is present, the center line of the head B ₁ of the track will not match, the state in FIG 9 a (δ = -δS) and state c
As shown in (δ = δS), the magnetic head runs off the track, and a portion that is not reproduced occurs in the track, and the reproduction output of the magnetic head is reduced.

[0067] That is, as shown in FIG. 10, the head relative height δ is zero, the output from the head is the maximum output V _max, and the + or - reproduction output decreases as the relative height δ increases the I will do it. Further, when the top or bottom of the head B ₁ relative height is increased to reach the adjacent track (the relative height at this time is δ = ± E _1), thereafter reproduction output of the head B ₁ represents a constant _Vmin .
Note that E ₁ and V _min are respectively represented by the following equations.

E ₁ = 2 Tp−Wh V _min = V _max × (Wh−E ₁ ) / Wh (15) Then, when the magnetic head B ₁ completely leaves the track to be scanned (relative height δ = ± Wh), thereafter the head B ₁ represents becomes possible to reproduce only an adjacent track,
The reproduction output increases again.

In the first embodiment of the present invention, the offset signal to be applied to the actuators 100A and 100B for relative height adjustment is measured by utilizing the above-described properties. Here, the offset signal substantially means a voltage or a current applied to the actuators 100A and 100B.

Firstly, it is prepared stepwise advance several different offset signal to be applied to the actuator 100B to the magnetic head B ₁ is attached. The smaller the amount of change in each step, the more precise the relative height adjustment can be made.

Next, when the track b ₁ on which the pilot signal is recorded is traced by the head B ₁ , a plurality of offset signals prepared are sequentially applied to the actuator 100 B (step S 4), and the head corresponding to each offset signal is added. sequentially measuring the reproduction output of B ₁ (step S5). The offset signal applied to the actuator may be changed sequentially for each scan, or a plurality of types of offset signals may be added stepwise in one scan. The flowchart of FIG. 6 shows the latter example. After applying the prepared offset signals of all types to the actuator during one scanning period to detect the reproduction output level, the offset signal when the reproduction output reaches the maximum is detected (step S).
6). Therefore, for example, when the head relative height is δ, the displacement of the actuator corresponding to the offset signal that maximizes the head reproduction output is −δ.

(IV) Based on the above operation (III), that is, the information on the relative height δ detected in steps S4 to S6 in FIG.
The relative height adjustment of the head is performed.

Only for the actuator 100 B, −δ
And an offset signal corresponding to a displacement applied, the magnetic head B ₁ is -δ displaced (step S8). Actuator 100A to the magnetic head A ₁ is mounted this time is not displaced.

This method uses the actuators 100A and 1A.
This is effective when 00B are independently driven (for example, when an actuator having a form as shown in FIGS. 39 to 41 is used).

The actuators 100 A, 100 B
Then, an offset signal corresponding to a displacement of δ / 2, −δ / 2 is applied, respectively, and the magnetic heads A ₁ , B ₁ are displaced by δ / 2, −δ / 2 in opposite directions (step S8). ).

This method uses the actuators 100A and 1A.
00B are driven by the same drive circuit so as to be simultaneously and reversely displaced (for example, as described above with reference to FIGS. 42 to 46).
This is particularly effective when an actuator having the form shown in FIG. Note that this method uses the actuator 1
It is also applicable to a case where 00A and 100B are driven independently. The above operations (II), (III) and (I)
By repeating V) a plurality of times, the relative height can be adjusted with higher accuracy. In this way, the detection errors of the relative heights of the heads are averaged, and the relative heights δ of the magnetic heads A ₁ and B ₁ converge to zero. The flowchart of FIG.
Although an example is shown in which the operations (II), (III) and (IV) are repeated, this operation need not be repeated.
Alternatively, only the operations of (II) and (III) may be repeated, and the offset signal that maximizes the head reproduction output may be averaged. When the relative height adjustment is completed (step S
7) The offset signals applied to the actuators 100A and 100B at that time are stored (step S9). This offset signal is called an optimal offset signal. Thereafter, with the optimum offset signal constantly applied to the actuators 100A and 100B (step S9), the tape is rewound, and a normal signal is recorded while erasing the recording track (step S1).
0).

As described above, the relative height adjustment may be performed immediately before regular signal recording is performed, or may be performed periodically at a certain interval irrespective of regular signal recording. . For example, since an ordinary VTR has a built-in timer, an interval for adjusting the relative height of the head is set in advance. Then, when it is time to perform the adjustment, for example, when the power switch is turned off by the user, the user is notified by some display that the head height adjustment is to be performed.

In response to this, the user prepares a tape on which recording for head height adjustment can be performed, and
Set to R. Next, a portion of the tape where no signal is recorded is searched, and the relative height adjustment of the head is performed. According to the present invention, it is not necessary to erase the recorded track as described above, so basically any tape may be used. After the adjustment of the relative height of the head is completed by the above-described method, the adjustment track recorded on the tape may be erased as necessary.

[0079] Figure 11 (a) and (b), respectively, in the first embodiment of the present invention, it is a block diagram of a circuit connected to the head B ₁ and head A _1. In the embodiment of FIG. 11, the relative height is adjusted by applying the optimum offset signal only to the actuator 100B, and the offset signal applied to the actuator 100B in the process of detecting the optimum offset signal is changed for each scan. It is assumed that they are sequentially changed.

[0080] 11 (a), the head B ₁ represents, by a switch S _1, the pilot signal generator 14A, 14
B and a circuit system connected to the memory 20 for the optimal offset signal and the actuator 100B. First, at the time of recording a pilot signal, two types of pilot signals f ₁ and f ₂ generated by the pilot signal generators 14A and 14B are switched by the switch S2, and are magnetically switched by the head B ₁ via the amplifier 7 and the switch S1. Recorded on tape. The pilot signals f ₁ and f ₂ are alternately generated for each scan by the switch S ₂ in accordance with a timing signal formed by the timing control circuit 21 based on a pulse from the pulse generator PG and synchronized with one rotation of the rotating drum. Selected and recorded.

[0081] In FIG. 11 (b), the capstan control by head A ₁ is performed as follows. Head A
After being reproduced by the amplifier 6, the reproduced signal from ₁ is subjected to band-pass filters (PBF) 9 A, 9 B and a detector (D
ET) By two circuits consisting of 10A and 10B,
The level is detected for each frequency component of pilot signals f ₁ and f ₂ . The detected levels are compared by a comparator 11, and a capstan control circuit 12 and a capstan motor 13 are provided in accordance with the polarity and level of a difference signal extracted from the comparator.
Controls the tape running.

[0082] Next, returning to FIG. 11 (a), for the detection of the optimum offset signal, the playing of the pilot signal is performed by the head B _1. At this time, the reproduction output of the head B ₁ represents, via the switch S1 is amplified by the amplifier 8 is detected by a detector (DET) 10C. Then, the reproduction output is measured by the level detector 15. At this time,
The actuator 100B of the head B ₁ side for each scan
Then, an offset signal of a plurality of stages prepared in advance by the offset generator 16 is applied via the actuator drive circuit 17 in synchronization with the timing pulse from the timing control circuit 21.

The offset signal added during each scan and the reproduced output detected by the level detector 15 are input to the optimum offset signal detector 19, which outputs the offset signals of all stages and the After the corresponding reproduction output is input, the offset signal when the reproduction output becomes maximum is output as the optimum offset signal and stored in the memory 20. Here optimum offset signal stored, as the offset signal for the relative height adjustment of the head during normal signal recording, is applied to the actuator 100B of the head B _1.

As described above, according to the first embodiment of the present invention, a plurality of tracks are formed as a reference for adjusting the relative height of a pair of magnetic heads, and the plurality of tracks are formed of a plurality of magnetic heads. Are sequentially scanned to detect and adjust the relative height. Therefore, the relative height detection error can be averaged, and the relative height detection error due to a poor contact between the magnetic tape and the magnetic head and an unstable magnetic tape position can be reduced.

Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG. In this embodiment, each of the magnetic head groups AT and BT includes two or more n magnetic heads A ₁ , A ₂ ,..., _An and B ₁ , B ₂ ,
.., _Bn . Here, 1 of the divisor of n excluding 1
One is k. At this time, n and k have the following relationship.

N = mk (m: natural number, m ， n) (16) In the following description, n is an even number and m is an odd number.

[0087] (I) First, tape speed V _t2 or is set to 1 / k times the normal recording playback speed V _t, or rotational speed V _h2 legitimate recording playback speed V of the magnetic head group
_It is set to k times _h (step S11). Where n ₁ =
Since k, the following relationship is obtained from equations (12) and (13).

L2 (180 °) · sin θ2 = m · Tp (17) L2 (360 °) · sin θ2 = 2m · Tp (18) where L2 (180 °) and L2 (360 °) are respectively And the magnetic head groups AT and BT are 180 ° and 360 °
The distance traveled by the magnetic tape during rotation, θ2
Is the track angle.

That is, the magnetic head A of the magnetic head group AT
_j (the magnetic head B _j of the magnetic head group BT) has a magnetic tape scanning locus separated by a distance of 2 m · Tp for each rotation.
When the relative height δ between the magnetic head groups AT and BT is zero, the scanning loci of the magnetic heads A _j and B _j on the magnetic tape are separated by a distance of m · Tp. On the other hand, the scanning trajectory on the magnetic tape between the magnetic head A _j and the magnetic head A _{j + m} of the magnetic head group AT is separated by a distance of m · Tp (1 ≦ j, j + m ≦ n).

Therefore, the magnetic head B _j of the magnetic head group BT follows the same locus as the scanning locus on the magnetic tape of the magnetic head A _{j + m} of the magnetic head group AT with a delay of 180 °. Similarly the magnetic head A _j of magnetic head group AT follows the exact same path as the scanning locus on a magnetic tape of the magnetic head B _{j + m} of magnetic head group BT 180 ° delayed by.

(II) With the tape speed _Vt2 or the rotational speed _Vh2 of the magnetic head group set as described above, recording of a signal serving as a reference for adjusting the relative height between the magnetic head groups AT and BT is performed. Perform (step S12). Signal of 2m magnetic heads of magnetic head group AT, for example, recorded by the magnetic head A ₁ to A _2m, magnetic head group BT is not used.
At this time, the actuator 100A equipped with the magnetic head group AT is not operated. Figure 13 is a track pattern in this case, the magnetic head A ₁ to A _2m tracks _{a 1, a 2, ...,} a 2m, a 1, to form a ....

Here, the tracks a ₁ and a ₁ are 2 m · Tp
And at a distance of, each of the tracks a ₁ ~a _2m, predetermined track width Tw and the track pitch Tp (Tw =
Tp). Since signals are recorded only in the magnetic head group AT as described above, no matter what the relative height δ between the magnetic head groups AT and BT is,
The formed track pattern is the same as in FIG.

The magnetic heads A _{1 to} A _{2m of the} magnetic head group AT
There tracks _{a 1, a 2, ...,} a 2m, a 1, a signal to be recorded to ... may be any cyclical signals based on certain rules. For example, pilot signals f ₁ and f of different frequencies
A signal obtained by cyclically superimposing ₀ , f ₂ , f ₀ , f ₁ ,... On the main signal may be used. The superimposition of the pilot signal f ₀ indicates that only the main signal is recorded and nothing is superimposed. Further, the frequency of the pilot signal is set to a low frequency so that it can be reproduced even by magnetic heads having different azimuths. After recording the pilot signal for a certain period, the magnetic tape is rewound (step S12),
The reproducing operation by the magnetic head groups AT and BT for adjusting the relative height is started.

(III) Next, a reproducing operation by the magnetic head groups AT and BT for adjusting the relative height will be described. In this reproducing operation, both the magnetic head groups AT and BT are used.

(III-i) At least one magnetic head of one of the magnetic head groups, for example, the magnetic head group AT, for example, the magnetic head A _{j1 + m} (1 ≦ j1, j1)
+ M ≦ n) are adjacent to the track a _j and are 2Tp from each other.
The tape running control by the capstan control is performed so that the pilot signals f2 and f1 of the _two tracks _aj-1 and _{aj + 1} separated by a distance from _{each other} are evenly reproduced (step S1).
3). By this tape running control, the magnetic head A _{j1 + m}
Of the scanning track coincides with the center of the track _aj . This is shown in FIG.

At this time, the actuator 100A equipped with the magnetic head group AT is not operated. The tape running control is repeatedly performed by rotating the magnetic head group AT a plurality of times until the above-described target is achieved (step S14). Note that if sufficient tape running control can be performed while the magnetic head group AT scans the magnetic tape once, it is not necessary to repeat the above-described scanning.

(III-ii) With the tape running control being performed as described above, a signal is reproduced by the magnetic head _Bj1 of the magnetic head group BT. FIG. 15 shows the positional relationship between the track and the magnetic head group BT. Here, δ is the magnetic head group BT with respect to the magnetic head group AT.
Represents the relative height of When δ = 0 (position P0 in the figure), the magnetic head B _j1 is _replaced by the magnetic head A _{j1 + m} as described above.
Scans exactly the same trajectory as
track _{a j-1, a j +} 1 of the pilot signal f _2, f ₁ and the adjacent _j play equally. On the other hand, when δ ≠ 0 (positions P1 and P2 in the figure), the levels of the pilot signals f ₁ and f ₂ reproduced by the magnetic head B _j1 are different from each other. Here, the level difference between the pilot signals f ₁ and f ₂ is referred to as an error signal Sp as follows.

Sp = (reproduction level of pilot signal f ₁ ) − (reproduction level of pilot signal f ₂ ) (19) FIG. 16 is a graph showing a relationship between the relative height δ and the error signal Sp. . The detection of the relative height δ is specifically performed by, for example, the following method.

(A) The actuator 100B is controlled so that the error signal Sp becomes 0, and an offset signal applied to the actuator 100B at that time is obtained (step S15). When the relative height is δ, the displacement corresponding to the above-described offset signal that sets the error signal Sp to 0 corresponds to −δ. Note that the offset signal is the actuator 1
It means voltage or current applied to 00A and 100B.

(B) The relative height δ is directly detected from the error signal Sp reproduced by the magnetic head B _j1 (step S1).
5).

[0102] Note here has been detected the relative height by using the magnetic head B _j1, magnetic head B _{j1 + 2c} (c is an integer) it is the same with.

(IV) Based on the information on the relative height δ detected in step S15 as described above, the relative height is adjusted by, for example, the following method.

Only for the actuator 100B, −δ
Is applied, and the magnetic head group BT is displaced by -δ (step S17). At this time, the actuator 100 on which the magnetic head group AT is mounted
A is not displaced.

This method uses actuators 100A and 1A.
This is effective when 00B are independently driven (for example, when an actuator having a form as shown in FIGS. 39 to 41 is used).

The actuators 100A and 100B
The magnetic head groups AT and BT are displaced by δ / 2 and −δ / 2 in opposite directions, respectively, by applying an offset signal corresponding to a displacement of δ / 2 and −δ / 2 (step S17). ).

This method uses actuators 100A and 100A.
00B are driven by the same drive circuit so as to be simultaneously and reversely displaced (for example, as described above with reference to FIGS. 42 to 46).
This is particularly effective when an actuator having the form shown in FIG. Note that this method uses the actuator 1
It is also applicable to a case where 00A and 100B are driven independently.

By repeating the above reproducing operations (III) and (IV) for head height adjustment a plurality of times,
The detection errors of the relative heights of the magnetic head groups are averaged, and the relative heights δ of the magnetic head groups AT and BT converge to zero. If the relative height adjustment is completed (Step S1
6) The offset signal applied to the actuators 100A and 100B at that time is stored (step S1).
8). This offset signal is called an optimal offset signal.

Thereafter, the actuators 100A, 100A
The tape is rewound with the optimum offset signal constantly applied to B (step S18), and a normal signal is recorded while erasing the recording track (step S2).
0). When performing normal signal recording, the tape speed or the rotation speed of the magnetic head group is reset to the normal speed (step S19).

FIG. 17 is an example of a block diagram of a circuit connected to the magnetic head groups AT and BT in the second embodiment. In this figure, the magnetic head groups AT, B
An example is shown in which T is composed of two magnetic heads A ₁ and A ₂ and B ₁ and B ₂ respectively. The operation of the circuit shown in FIG. 17 will be described with reference to the flowchart of FIG. In this example, n = 2, k = 2, m = 1, and j1 = 1.

(I) The 1/2 speed setting circuit 44 and the capstan control circuit 37 set the tape speed to 1/2 speed at the time of normal recording / reproduction (step S11). Note that the number of rotations of the rotating drum 1 may be set to twice that of normal recording and reproduction.

(II) From recording / reproducing switching signal generating circuit 41
Switch S by the recording / playback switching signal of _Three, S_FourRecord mode
(Step S12). Pilot signal generation
The two types of pilots generated by the detectors 32B and 32C
Signal f₁, F_TwoOverlaps with the main signal from the main signal source 32A.
After being folded, switch S_Five, Amplifier 30, switch S _Three
Through the magnetic head A₁Recorded on magnetic tape
It is.

[0112] The pilot signal f _1, f ₂ is made of the timing control circuit 43 is switched by a switch S ₅ in accordance with a timing signal synchronized with one rotation of the rotary drum 1, in each scanning of the magnetic head A ₁ Selected and recorded alternately. Magnetic head A ₂ records the main signal supplied via an amplifier 31 and a switch S _4.

(III) The switches S ₃ and S ₄ are set to the reproduction mode by the recording / reproducing switching signal from the recording / reproducing switching signal generating circuit 41 (S13). The switch S is controlled by the control head switching signal from the control head switching signal generation circuit 42.
_6, the S ₇ switching, head for traveling control (the magnetic head A ₂ in this example), selects respectively the (magnetic head B ₁ represents in this example) head for the relative height detection. The switches S ₈ and S ₉ are switched and controlled by a timing signal synchronized with １ ／ rotation of the rotary drum 1 obtained from the timing control circuit 43, and when the magnetic head A ₂ scans the tape, the tape running control and the magnetic head B _{When 1} scans the tape, the relative height detection is performed.

(III-i) The signal reproduced by the magnetic head A ₂ passes through the switches S ₄ , S ₆ and S ₈ ,
After being amplified by the amplifier 33, the band-pass filter 34
A, 34B, detector 35A, the 35B, is level detected for each of the frequency components of the pilot signals f _1, f _2. The results are compared by a comparator 36, and a tape running control is performed by a capstan control circuit 37 and a capstan motor 38 according to the polarity and level of the difference signal extracted from the comparator 36 (step). S13).

(III-ii) The signal reproduced by the magnetic head B ₁ passes through the switches S ₇ and S ₈ , is amplified by the amplifier 33, and then passed through the band-pass filters 34 A and 34.
4B and the detectors 35A and 35B, the pilot signal f
_1, is the level detection for each frequency component of f _2. Then, those results are compared by the comparator 36 (step S15).

(IV) The actuators 100A and 100B are displaced by the actuator drive circuit 39 according to the error signal Sp (relative height δ) detected by the comparator 36 (step S17).

The above operations (III) and (IV) are repeated a plurality of times and the relative height δ becomes zero (step S
16) is stored in the memory 40, and the optimum offset signal is applied to the actuators 100A and 100B (S1).
8).

As described above, according to the second embodiment of the present invention, a plurality of tracks serving as a reference for head height adjustment are formed, and two magnetic head groups sequentially scan the plurality of tracks. To detect and adjust the relative height. Therefore, the relative height detection error can be averaged, and the relative height detection error due to a hitting failure, an unstable magnetic tape position, or the like can be reduced.

Next, a third embodiment of the present invention will be described. The third embodiment is different from the second embodiment in that a magnetic head for signal recording is used and a part of a method of detecting a relative height δ, and other operations are the same. .

[0120] (I) or a tape speed V _t2 is set to 1 / k times the speed V _t during normal recording and reproduction, or the rotational speed V _h2 of the magnetic head group recording reproduction rate V _h of normal k
Set to double.

[0121] (II) the magnetic head A ₁ of every other one of the magnetic heads _{A 1 ~A 2m, A 3,} A 5, ..., to record the signal by A _2m-1, tracks a _1, a _3, a _5, ...,
a _{2m −1} , a ₁ ,... FIG. 18 shows a part of the track pattern at this time, and the track width of each track is W
h, the track pitch is 2Tp. This track pattern is the same as in the first embodiment. Track a ₁ ,
_{a 3, a 5, ...,} a 2m -1, a 1, the ..., for example, different pilot signals f ₁ frequency, f _2, f _1, and records the ... cyclically. Note that the pilot signal may be recorded while being superimposed on the main signal.

(III-i) Magnetic head A _{ji + m} (1 ≦
j1, j1 + m ≦ n) is, to reproduce equally pilot signals f _2, f ₁ of the two tracks a with a distance of 2Tp _j1, a _{j + 1,} tape travel control by the capstan control Perform This is shown in FIG.

(III-ii) With the tape running control being performed as described above, signals are reproduced by the magnetic heads of the magnetic head group BT. The magnetic head used here is the magnetic head B _j1 or the magnetic head B _{j1 + 1} . The following operation differs depending on which magnetic head is used. FIG. 19 shows the positional relationship between the track and the magnetic head group BT. The magnetic heads B _{j1 + 2c} ,
The operation is the same even when the magnetic head B _{j1 + (2c + 1 )} (c is an integer) is used.

(III-ii-a) When the magnetic head B _j1 is used: When the relative height δ is 0, the magnetic head B _j1 scans exactly the same locus as the magnetic head A _{j1 + m} . track _{a j-1, a j +} 1 of the pilot signal f _2,
f ₁ is reproduced uniformly, and the error signal Sp becomes 0. Therefore, the relative height δ can be detected from the error signal Sp in the same manner as in the second embodiment.

(III-ii-b) Magnetic head B _{j1 + 1}
Is used: When the relative height δ is 0, the magnetic head B
The center of the scanning locus of _{j1 + 1} coincides with the center of the track _{aj + 1} , and the reproduction output of the magnetic head _{Bj1 + 1} becomes maximum. Therefore, the relative height δ can be detected from the reproduction output level of the magnetic head B _{j1 + 1 in} the same manner as in the first embodiment. The following operations and effects are the same as those of the above-described second embodiment, and thus description thereof will be omitted.

Next, fourth to eighth embodiments of the present invention will be described. These embodiments correspond to the first to third embodiments described above.
After the relative height is adjusted by the embodiment, the relative height deviation over time during normal signal recording can also be corrected. The relative height deviation over time is a constant offset signal (constant voltage or constant current) applied to the actuator.
Can be supplied, for example, due to the aging of the actuator itself.

FIG. 20 shows the drum device 3 of these embodiments.
FIG. The magnetic head groups AT and BT are provided with test surfaces 101A and 101B, respectively, and the drum device 3 is provided with at least one sensor for detecting the height of the test surface. In FIG. 20, the test surface 101
A and 101B are actuators 100A and 1B, respectively.
00B. The sensor may be disposed on the fixed drum side, the rotating drum side, or outside the drum device, and the detection method may be a known method such as a capacitance method, an eddy current method, or an optical method. . As an example of the above-mentioned sensor, in FIG. 20, one capacitance sensor 110 is arranged on the fixed drum 2 side. The capacitance sensor 110 can sequentially face the test surfaces 101A and 101B, and detects the capacitance therebetween to determine the height of the test surface. The test surfaces 101A and 101B
Is formed of a conductive material such as aluminum or copper.

Here, when the relative height adjustment is completed in the first to third embodiments, the test surfaces 101A and 101B
Are different by h1 as shown in FIG. At this time, the sensors 11 on the test surfaces 101A and 101B
The distances hA (0) and hB (0) for 0 are different, and the corresponding sensor outputs VA (0) and VB (0) are also different. It is assumed that the distance-output characteristic of the sensor 110 is non-linear as shown in FIG.

Next, the fourth embodiment will be specifically described with reference to the above description. This embodiment is also applied to the case where the relative height is adjusted by the above-described first to third embodiments and other relative height adjustment methods. In the present embodiment, the actuators 100A, 10A
OB is independently driven by independent driving circuits (for example, when an actuator having a form as shown in FIGS. 39 to 41 described above is used).

First, when the relative height adjustment is completed, the sensor output VA with respect to the test surfaces 101A and 101B is obtained.
(0) and VB (0) are respectively detected and stored. Then, at the time of normal signal recording thereafter, the test surface 101
Actuators 100A and 100B are controlled such that sensor outputs VA 'and VB' for A and 101B match VA (0) and VB (0), respectively.

FIG. 23 is a block diagram for realizing this operation. In FIG. 23, test surfaces 101A, 101
The outputs VA 'and VB' of the sensor 110 with respect to B are respectively compared with the target values VA (0) and VB (0), and the actuator driving circuits 39A and 39B are controlled based on the results. By this operation, the test surfaces 101A, 101B
Can always be maintained at hA (0) and hB (0). That is, the relative height of the magnetic head groups AT and BT can be corrected to 0 even during normal signal recording.

Next, a fifth embodiment of the present invention will be specifically described. This embodiment is similar to the second and third embodiments described above.
Applied to the embodiment, the magnetic head groups AT, BT
Represents n or more n magnetic heads A ₁ , A ₂ ,
..., A _n and B _1, B _2, ..., consisting of B _n. In this embodiment, the actuators 100A and 100B are simultaneously driven by the same drive circuit (for example, when the actuators having the forms shown in FIGS. 42 to 46 are used), and the actuators 100A and 100B
0B is independently driven (for example, when an actuator having a form as shown in FIGS. 39 to 41 is used). In the former case, the actuators 100A and 100B that are displaced in directions opposite to each other are used.

First, a method of calibrating the displacement-output curve of the sensor 110 will be described with reference to the flowchart of FIG. In the following example, a method of calibrating the output characteristics of the sensor 110 with respect to the test surface 101A will be described.
The same applies to 1B.

(I) First, when the relative height adjustment of the magnetic head groups AT and BT is completed (S21), the sensor output V
A (0) is detected and stored (S22).

(II) The second and third embodiments described above
In the same manner, the magnetic head A of the magnetic head group AT_j1By
To control the tape running (steps S23 and S23).
24). This is shown in FIG. Acti in this state
When the heater 100A is driven (step S25),
With the displacement of the magnetic head group AT, the magnetic head A_j1, Magnetic
A_{j1 + 1}The reproduced error signal Sp of FIG.
And changes like a solid line and a dotted line. In FIG.
Indicates the error signal level for each magnetic head.
Normalization is performed at each maximum level. That is, magnetic
Head A_j1Is 2I ₁・ Tp, magnetic head A_{j1 + 1}Is (2I
₁+1) · Tp, the error signal Sp becomes 0 at every displacement.
You. Where I₁Is an integer.

(III) When the magnetic head group AT scans the magnetic tape, the actuator 100A is moved to the position shown in FIG.
It is driven in the middle A direction (step S25). When the error signal Sp obtained from the magnetic head A _{j1 +1} becomes 0 (steps S26 and S27), the actuator 100A is maintained at that height. In this state, when the test surface 101A (actuator 100A) rotates and comes to a position facing the sensor 110, the output VA (i) of the sensor 110 is detected and stored (Step S28). Then, the next (I
The operation of V) is performed. VA (i) represents a sensor output when the magnetic head group AT is displaced by i · Tp in the A direction.

(IV) When the magnetic head group AT scans the magnetic tape, the actuator 100A is driven in the direction A again (step S25). When the error signal Sp obtained from the magnetic head A _j1 becomes 0 (steps S26 and S27), the actuator 100A is maintained at that height. In this state, the test surface 101A (actuator 1
00A) rotates and comes to a position facing the sensor 110, the output VA (i) of the sensor 110 is detected and stored. After that, the operation (III) is performed.

(V) The above operations (III) and (IV) are repeated to obtain a required number I of VA (i) (step S29), and then the actuator 100A is set so that the sensor output VA (0) is obtained. Is displaced (step S
34 and S35).

(VI) In the state where the magnetic head group AT has returned to the height at the time of the relative height adjustment by the operation of the above (V),
The tape running control is performed by the magnetic head A _j1 of the magnetic head group AT. Thereafter, the actuator 100A is driven in the direction B in FIG. 25, and the same operations as (III) and (IV) are repeated. When the necessary number I of VA (i) is collected, the actuator 100A is displaced so that the sensor output becomes VA (0).

(VII) VA obtained by the above operation
Using (i), the sensor 110 for the test surface 101A
Calibrate the displacement-output curve of FIG. 27 shows an example. VA (i) which is discrete data may be interpolated by an appropriate method such as polynomial approximation.

By the above operations (I) to (VII),
−I · T of the magnetic head group AT (the test surface 101A) based on the height of the magnetic head group AT when the relative height adjustment is completed.
This means that the sensor output has been calibrated for the displacement of p to + I · Tp. By the same method, the displacement-output curve of the sensor with respect to the magnetic head group BT (the test surface 101B) based on the height of the magnetic head group BT when the relative height adjustment is completed is also calibrated. As a result, the curve of the distance from the sensor and the sensor output in FIG. 22 described above is hA (0) -I
Tp to hA (0) + I.Tp range and hB (0)
This means that calibration has been performed in the range of −I · Tp to hB (0) + I · Tp. In this description, the magnetic head A
_Although the sensor output when the error signal Sp of _j1 and A _{j1 + 1} becomes 0 is detected, when applied to the above-described third embodiment,
The sensor output when the reproduction output of the magnetic heads A _j1 and A _{j1 + 1} is maximum may be detected. These may be combined.

Next, a method of detecting and correcting the relative height deviation over time during normal signal recording according to the fifth embodiment will be described with reference to the block diagram of FIG. In FIG. 28, displacement amount detection circuits 111A and 111B
For each magnetic head group, the sensor output is converted into a displacement based on the height at the time of relative height adjustment based on the displacement-output curve of the sensor obtained as described above. .

At the time of normal signal recording, the height of the test surfaces 101A and 101B is detected by the sensor 110. Sensor output V for each of test surface 101A (magnetic head group AT) and test surface 101B (magnetic head group BT)
From A 'and VB', the displacement amounts of the magnetic head groups AT and BT are detected by displacement amount detection circuits 111A and 111B. By comparing the obtained displacement amounts of the magnetic head groups AT and BT with the comparator 112 and calculating the difference, a relative height shift due to the temporal change of the magnetic head groups AT and BT is detected.

By controlling the actuators 100A and 100B so that the difference between the displacement amounts becomes zero, the offset signal applied to the actuators 100A and 100B is corrected, and the relative height of the magnetic head groups AT and BT over time is corrected. The displacement is corrected. Although FIG. 28 shows the case where the actuators 100A and 100B are simultaneously driven in the opposite directions by the same drive circuit 39, the basic concept is the same when only the actuator 100B is operated.

Next, a sixth embodiment of the present invention will be described. This embodiment is applied to the above-described first embodiment, and the magnetic head groups AT and BT each include one magnetic head A ₁ and B ₁ . In this embodiment, similarly to the above-described fifth embodiment, when the actuators 100A and 100B are simultaneously driven by the same drive circuit (for example, when the actuators having the forms shown in FIGS. 42 to 46 are used). , And when the actuators 100A and 100B are independently driven (for example, when the actuators having the forms shown in FIGS. 39 to 41 are used). In the former case, the actuators 100A and 100B are displaced in directions opposite to each other.

The method of detecting and correcting the relative height deviation over time during normal signal recording is the same as that in the block diagram of the above-described fifth embodiment (FIG. 28). Only the curve calibration method, Figure 2
9 will be described along the flowchart.

(I) First, when the relative height adjustment of the magnetic heads A ₁ and B ₁ is completed (step S41), the sensor output VA (0) for the test surface 101A is detected and stored (step S42). ).

[0148] In (II) similar to the first embodiment method, performing tape running control by magnetic head A ₁ (step S43~S44). This is shown in FIG. When driving the actuator 100A in this state, in association with the displacement of the magnetic heads A _1, error signal Sp to the reproduction of the magnetic head A ₁ changes as shown in FIG. 31. That is, the error signal Sp becomes 0 every time the magnetic head A ₁ is displaced by 2I ₁ · Tp, and the absolute value of the error signal Sp becomes the maximum every time the magnetic head A ₁ is displaced by (2I ₁ +1) · Tp (reproduction output level Is the largest). Here, I ₁ is an integer.

[0149] (III) the magnetic head A ₁ is when scanning a magnetic tape, and drives the actuator 100A in the direction A in FIG. 30 (step S47~S48). First
When the maximum value of the error signal Sp obtained from the magnetic head A ₁ is maximum (when the reproduction output level is maximum), the actuator 100 is operated in the same manner as the embodiment.
A offset signal applied to A is detected (step S4).
9). Thereafter, the detected offset signal is applied to the actuator 100A (step S50), and the magnetic head A
₁ is maintained at the height when the absolute value of the error signal Sp is maximum (when the reproduction output level is maximum).

In this state, when the test surface 101A (actuator 100A) rotates and comes to a position facing the sensor 110, the output VA (i) of the sensor 110 is detected and stored (step S51). Thereafter, the following operation (IV) is performed. Incidentally, VA (i) represents the sensor output when magnetic head A ₁ is displaced by i · Tp in the A direction.

[0151] (IV) the magnetic head A ₁ is when scanning a magnetic tape, again driven in the direction A of the actuator 100A (step S53). If the error signal Sp is 0 obtained from the magnetic heads A _1, (Step S54~
S55), maintaining the actuator 100A at that height. In this state, the test surface 101A (actuator 100
When A) rotates and comes to a position facing the sensor 110, the output VA (i) of the sensor 110 is detected and stored (step S56). Thereafter, the above-mentioned operation (III) is performed.

(V) After the operations of (III) and (IV) are repeated to collect a required number of VA (i) (step S45), the actuator 100A is set so that the sensor output becomes VA (0). Is displaced (step S
58-S59).

[0153] The operation of (VI) above (V), in a state where the magnetic head A ₁ is returned to the height at the time of the relative height adjustment completion, performing tape running control by magnetic head A _1.
Thereafter, the actuator 100A is driven in the direction B in FIG. 30, and the same operations as the above (III) and (IV) are repeated. When the required number of VA (i) is collected, the actuator 100A is set so that the sensor output becomes VA (0).
Is displaced.

(VII) VA obtained by the above operation
Using (i), the displacement-output curve of the sensor 110 with respect to the magnetic head A ₁ (the test surface 101A) is calibrated. The method of calibration is the same as in the fifth embodiment (FIG. 27).

In the same manner as described above, the magnetic head B
The displacement-output curve of the sensor with respect to ₁ (the test surface 101B) is also calibrated.

Next, a seventh embodiment of the present invention will be described. This embodiment is also applicable to the case where the height is adjusted by the above-described first to third embodiments and other relative height adjustment methods. Also, in this embodiment,
Similarly to the above-described fifth and sixth embodiments, when the actuators 100A and 100B are simultaneously driven by the same drive circuit (for example, when the actuators having the forms shown in FIGS. 42 to 46 are used). Also, the present invention can be applied to any of the cases where the actuators 100A and 100B are independently driven (for example, when the actuators having the forms shown in FIGS. 39 to 41 are used). In the former case, the actuator 1
00A and 100B are displaced in directions opposite to each other. FIG. 32 is a bottom view of the rotating drum 1 according to this embodiment.
A and a plurality of test surfaces 101A _i (i = −I to + I) are provided with predetermined steps in the height direction. FIG.
Shows an example of I = 1. The height of the test surface 101A is located at the center of these test surface heights. The above-mentioned step may be determined according to the correction accuracy of the relative height shift,
For example, it may be one track pitch (1 Tp).
Figure 33 shows the test surface 101A, the height relationship 101A _i schematically. Note that this example shows a case where I = 2.

Next, the operation of this embodiment will be described. First, when the relative height adjustment of the magnetic head groups AT and BT is completed, the sensor output VA (0) with respect to the test surface 101A.
And detecting a sensor output VA (i) with respect to the test surface 101A _i, and stores. Here, VA (i) is the test surface 101A.
It represents the sensor output for a position higher by i · Tp.

Using the detected sensor output VA (i),
In the same manner as in the fifth embodiment (FIG. 27), the magnetic head group A
The displacement-output curve of the sensor 110 with respect to T (the test surface 101A) is calibrated. In the same manner as above, the displacement of the sensor with respect to the magnetic head group BT (the test surface 101B)
The output curve is also calibrated. The method of detecting and correcting the relative height deviation over time during normal signal recording is the same as that shown in the block diagram of the fifth embodiment (FIG. 28), and thus the description is omitted.

Next, an eighth embodiment of the present invention will be described. This embodiment is also applicable to the case where the height is adjusted by the above-described first to third embodiments and other relative height adjustment methods. In this embodiment, the fifth
Similarly to the seventh embodiment, when the actuators 100A and 100B are simultaneously driven by the same drive circuit (for example, when the actuators having the forms shown in FIGS. 42 to 46 are used), The present invention can be applied to any of the cases where the 100Bs are driven independently of each other (for example, when the actuators having the forms shown in FIGS. 39 to 41 are used). In the former case, the actuators 100A and 100B are displaced in directions opposite to each other.

FIG. 34 is a bottom view of the rotary drum 1 of this embodiment.
In a portion where 100B is not located, a plurality of reference planes PR1,
, PRq are provided with predetermined steps in the height direction. The step may be determined in accordance with the correction accuracy of the relative height shift, for example, for one track pitch (1T
p).

FIG. 35 shows reference planes PR1, PR2,.
The height relationship of Rq is schematically shown. Here, the height of the reference plane PR1 is lower than the minimum height of the operation range of the test surfaces 101A and 101B, and the height of the reference plane PRq is the highest of the operation range of the test surfaces 101A and 101B. It shall be set at a position higher than the height.

Next, the operation of this embodiment will be described. In this embodiment, the distance-output curve of the sensor 110 based on the height of the reference plane PR1 is calibrated from the output of the sensor 110 for the reference planes PR1, PR2,..., PRq.
The calibration method is the same as in the fifth embodiment (FIG. 27). Note that the calibration is performed every time the sensor output for the test surfaces 101A and 101B is detected.

First, when the relative height adjustment is completed, the sensor output VA for the test surfaces 101A and 101B is set.
(0), VB (0) are detected. These sensor outputs V
A (0) and VB (0) are converted to heights HA (0) and HB with respect to the reference plane PR1 based on the above-described distance-output curve.
Convert to (0). Thereafter, the difference between HA (0) and HB (0) (HA (0) -HB (0)) is obtained and stored.

Next, a method of detecting and correcting the relative height deviation over time during normal signal recording according to the eighth embodiment will be described with reference to the block diagram of FIG. At the time of normal signal recording, the test surfaces 101A, 1 at that time
The sensor outputs VA 'and VB' for each of the signals 01B and 01B are detected. These sensor outputs VA 'and VB' are converted into heights HA 'and HB' with respect to the reference plane PR1 based on the aforementioned distance-output curve. The above heights HA ', H
The detection of B 'is performed by the distance detection circuit 113 in FIG. The heights HA 'and HB' are compared with the comparators 112.
So that the difference HA′−HB ′ becomes equal to the difference HA (0) −HB (0) when the relative height is adjusted.
By controlling the actuators 100A and 100B, the relative height deviation of the magnetic head groups AT and BT over time is corrected.

[0165]

As described above, according to the present invention, a plurality of tracks serving as a reference for adjusting the relative height between two sets of magnetic head groups are formed, and the plurality of tracks are formed by the magnetic head group. Sequential scanning is performed to detect and adjust the relative height. Therefore, it is possible to adjust the relative height of the two sets of recording / reproducing magnetic head groups mounted on the actuator with high accuracy.

Further, at the time of normal signal recording after the relative height adjustment, the relative height deviation between the magnetic head groups over time can be detected and corrected. Therefore, a track having a predetermined track width and a predetermined track pitch can be formed during signal recording. Therefore, even if the track pitch is significantly narrowed, a sufficient reproduction output that satisfies the specifications of the apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a rotary drum used in the present invention.

FIG. 2 is a bottom view of a rotary drum used in the present invention.

FIG. 3 is a diagram illustrating a configuration of a magnetic head group used in the present invention.

FIG. 4 is a diagram showing a track pattern by a magnetic head group used in the present invention.

FIG. 5 is a diagram showing a track pattern during normal signal recording by a magnetic head group used in the present invention.

FIG. 6 is a flowchart illustrating a head height adjusting method according to the first embodiment.

FIG. 7 is a schematic diagram illustrating a head height adjusting method according to the first embodiment.

FIG. 8 is a schematic diagram illustrating a head height adjusting method according to the first embodiment.

FIG. 9 is a schematic diagram illustrating a head height adjusting method according to the first embodiment.

FIG. 10 is a graph showing the relationship between the relative height of the head and the reproduction output of the head according to the first embodiment.

FIG. 11 is a block diagram of a head height adjusting device according to the first embodiment.

FIG. 12 is a flowchart illustrating a head height adjusting method according to a second embodiment.

FIG. 13 is a schematic diagram illustrating a head height adjusting method according to a second embodiment.

FIG. 14 is a schematic diagram illustrating a head height adjusting method according to a second embodiment.

FIG. 15 is a schematic diagram illustrating a head height adjusting method according to a second embodiment.

FIG. 16 is a graph showing a relationship between a relative height of a head and an error signal.

FIG. 17 is a block diagram of a head height adjusting device according to a second embodiment.

FIG. 18 is a schematic diagram illustrating a head height adjusting method according to a third embodiment.

FIG. 19 is a schematic diagram illustrating a head height adjusting method according to a third embodiment.

FIG. 20 is a schematic sectional view of a rotary drum used in the fourth to eighth embodiments.

FIG. 21 is a schematic diagram showing a relationship between a sensor and a height of a surface to be measured.

FIG. 22 is a graph showing displacement-output characteristics of a sensor.

FIG. 23 is a block diagram of a head height adjusting device according to a fourth embodiment.

FIG. 24 is a flowchart of a head height adjusting method according to a fifth embodiment.

FIG. 25 is a schematic diagram illustrating a head height adjusting method according to a fifth embodiment.

FIG. 26 is a graph showing a relationship between a displacement amount of a magnetic head group and an error signal.

FIG. 27 is a displacement-output calibration curve of a sensor according to the fifth embodiment.

FIG. 28 is a block diagram of a head height adjusting device according to a fifth embodiment.

FIG. 29 is a flowchart of a head height adjusting method according to a sixth embodiment.

FIG. 30 is a schematic diagram illustrating a head height adjusting method according to a sixth embodiment.

FIG. 31 is a graph showing a relationship between a displacement amount of a magnetic head and an error signal.

FIG. 32 is a bottom view of the rotary drum according to the seventh embodiment.

FIG. 33 is a schematic diagram illustrating a height relationship between a plurality of surfaces to be inspected according to a seventh embodiment.

FIG. 34 is a bottom view of the rotary drum according to the eighth embodiment.

FIG. 35 is a schematic diagram illustrating a height relationship between a plurality of reference surfaces according to the eighth embodiment.

FIG. 36 is a block diagram of a head height adjusting device according to an eighth embodiment.

FIG. 37 is a bottom view of a rotary drum of a conventional rotary head type magnetic recording / reproducing apparatus.

FIG. 38 is a schematic view showing a track pattern by a conventional magnetic head.

FIG. 39 is a bottom view of the rotary drum according to the present invention.

FIG. 40 is a sectional view of a drum device according to the present invention.

FIG. 41 is a sectional view of an example of a bimorph piezoelectric actuator applied to the present invention.

FIG. 42 is a schematic top view of a drum device applied to the present invention.

FIG. 43 is a schematic top view of a drum device to which the present invention is applied.

FIG. 44 is a sectional view of a drum device to which the present invention is applied.

FIG. 45 is a sectional view of a drum device to which the present invention is applied.

FIG. 46 is a perspective view of a parallel leaf spring of the drum device to which the present invention is applied.

[Explanation of symbols]

AT, BT magnetic head group _{A 1, A 2, B 1} , B 2 magnetic heads 6, 7, 8 amplifiers 9A, 9B bandpass filter 10A, 10B detector 11 comparator 12 capstan control circuit 13 a capstan motor 14A, 14B Pilot signal generation circuit 15 Level detector 16 Offset generation circuit 17 Actuator drive circuit 20 Memory 21 Timing control signal generation circuit 22 Recording / playback switching signal generation circuit 100A, 100B Actuator 101A, 101B Test surface

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toru Okuda 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-57-98131 (JP, A) 162468 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 5/588

Claims (29)

(57) [Claims] 1. A rotating drum, two sets of magnetic heads each including one or a plurality of magnetic heads, and a pair of magnetic head groups attached to the rotating drum, each displacing the two sets of magnetic heads in a track width direction. In a rotary head type magnetic recording / reproducing apparatus having a pair of actuators, a method of adjusting a relative height of the two magnetic head groups, wherein any one of the two magnetic head groups is Forming a plurality of tracks by cyclically recording, in a predetermined order, a plurality of types of signals predetermined for each track on a running magnetic tape by at least one of the constituent magnetic heads; Rewinding the magnetic tape after recording, and at least one magnetic head constituting one of the two magnetic head groups Controlling the running of the magnetic tape so that the signal is reproduced evenly from two tracks separated by a distance twice the track pitch at the time of recording a regular signal among the plurality of tracks; From the output obtained by reproducing the signal by at least one magnetic head constituting the other magnetic head group of the two magnetic head groups in the height adjustment mode in which the magnetic tape is controlled to run, the two magnetic head groups are separated from each other. Detecting information on the relative height of the magnetic heads, and adjusting the relative height between the two sets of magnetic heads based on the detected information. 2. A rotary head type magnetic recording / reproducing apparatus comprising: a rotary drum; a pair of magnetic heads; and a pair of actuators attached to the rotary drum and respectively displacing the pair of magnetic heads in a track width direction. An apparatus for adjusting a relative height between a pair of magnetic heads, wherein one of the pair of magnetic heads travels a plurality of types of signals predetermined for each track. Forming a plurality of tracks by cyclically recording in a predetermined order on a tape; rewinding the magnetic tape after recording the signal; and the plurality of tracks by the other of the pair of magnetic heads. Controlling the running of the magnetic tape so that signals from two tracks adjacent to each other with a gap are evenly reproduced; and In the travel-controlled height adjustment mode, a plurality of offset signals corresponding to the displacements of the actuators are prepared in advance, and the offset signals are sequentially applied to one of the pair of actuators corresponding to the one magnetic head. Detecting the output level of the signal reproduced from the one magnetic head while displacing the one magnetic head, and an offset signal when the output level of the reproduced signal is maximized. Detecting a relative height between the pair of magnetic heads as information about the relative height; and adjusting a relative height between the pair of magnetic heads based on the detected information. 3. The step of adjusting the relative height includes the step of: applying an offset signal as information relating to the relative height to at least one of the pair of actuators to compensate for the relative height. Obtaining an offset signal and storing the offset signal; and applying a stored optimum offset signal to at least one of the pair of actuator means during normal signal recording to compensate for a relative height between the heads. 3. The method of claim 2, comprising: 4. The rotating head type magnetic recording / reproducing apparatus further comprises: a test surface provided on each of the pair of magnetic heads; and at least one sensor for detecting a height of the test surface, The relative height adjustment method includes: storing an output of the sensor for each of the test surfaces when the step of adjusting the relative height between the pair of magnetic heads is completed; and Controlling the pair of actuators independently such that an output of the sensor detected for each of the test surfaces matches the stored sensor output. Method. 5. The rotary head type magnetic recording / reproducing apparatus further comprises: a test surface provided on each of the pair of magnetic heads; and at least one sensor for detecting a height of the test surface, Storing the output of the sensor for each of the test surfaces at the completion of the step of adjusting the relative height between the pair of magnetic heads; Storing the output of the sensor when the magnetic head provided with the test surface is displaced from the state where the relative height adjustment is completed by an integral multiple of the track pitch during normal signal recording. A displacement-output curve of the sensor, based on the sensor output stored for each of the test surfaces, based on the height when the relative height adjustment is completed for each of the test surfaces. And calibrating, at the time of normal signal recording, the sensor output detected for each of the test surface, based on the displacement-output curve calibrated for each of the test surface, respectively Converting the height to the displacement based on the height at the time of completion of the relative height adjustment, and the difference between the detected displacement of the test surface,
Calculating the relative height deviation of the pair of magnetic heads over time; and correcting the optimum offset signal applied to at least one of the actuators based on the calculated difference. The method of claim 3. 6. A step of detecting and storing the sensor output for calibrating a displacement-output curve of the sensor, wherein, for each of the pair of magnetic heads, two adjacent magnetic heads are separated by a gap. Controlling the running of the magnetic tape so that the signals from the tracks are evenly reproduced; displacing the magnetic head from this state; in the process, the two magnetic heads are separated by a gap. Detecting and storing the sensor output when the signals from the tracks are evenly reproduced and / or when the reproduction output of the signal reproduced by the magnetic head is maximized. the method of. 7. The rotating head type magnetic recording / reproducing apparatus, comprising: a plurality of test surfaces provided on each of the pair of magnetic heads, each of which is separated by a predetermined height; At least one sensor for detecting a height of a plurality of test surfaces, wherein the height adjustment method comprises: for each magnetic head, completing a step of adjusting a relative height between the pair of magnetic heads. Storing the output of the sensor for each of the plurality of test surfaces at a time; and for each magnetic head, a relative height to one of the test surfaces based on the stored sensor output. Calibrating a displacement-output curve of the sensor with reference to the height at the time of completion of the adjustment; and, for each magnetic head, a sensor detected with respect to one of the surfaces to be inspected during normal signal recording. Converting the output of the pair of magnetic heads into a displacement based on the height at the time of completion of the relative height adjustment, based on the calibrated displacement-output curve. Calculating a difference in the amount of displacement as a relative temporal displacement of the pair of magnetic heads; and correcting the optimum offset signal applied to at least one of the actuators based on the calculated difference. 4. The method of claim 3, further comprising the step of: 8. The rotary head type magnetic recording / reproducing apparatus, wherein: a test surface provided on each of the pair of magnetic heads; at least one sensor for detecting a height of the test surface; A first reference surface provided on the bottom surface of the rotary drum, and one or more second reference surfaces provided on the bottom surface of the rotary drum at a predetermined height from the first reference surface. The method further comprises: detecting the output of the sensor for each of the first and second reference planes; and detecting the height of the first reference plane based on the detected sensor output. Calibrating a distance-output curve of the sensor on the basis of the first reference plane based on the calibrated distance-output curve. Distance from Calculating the difference; storing the difference in distance at the time of completing the step of adjusting the relative height between the pair of magnetic heads; and Controlling the pair of actuators such that a difference in distance matches the difference in distance at the completion of the adjusting step. 9. A rotating drum, and two magnetic head groups each including n (n is an integer of 2 or more) magnetic heads,
A rotary head type magnetic recording / reproducing apparatus comprising: a pair of actuators attached to the rotary drum and displacing the two sets of magnetic heads in a track width direction.
A method of adjusting a relative height between the two sets of magnetic heads, wherein, when adjusting the relative height, the number of rotations of the rotary drum is set to k of the number of rotations during normal recording / reproduction (k is other than 1). Setting the running speed of the magnetic tape to 1 / k times the running speed at the time of normal recording / reproduction; and any one of the two magnetic head groups. By running at least one magnetic head constituting a group, a plurality of types of signals predetermined for each track at the set rotation speed of the rotating drum or at the set speed of the magnetic tape. Forming a plurality of tracks by cyclically recording in a predetermined order on a magnetic tape that is present; rewinding the magnetic tape after recording the signal; and one of the two sets of magnetic head groups. By at least one magnetic head constituting a magnetic head group, the signals are uniformly reproduced from two tracks of the plurality of tracks separated by a distance twice as long as the track pitch at the time of normal signal recording. Controlling the running of the magnetic tape; and controlling the running of the magnetic tape in a height adjustment mode in which the running of the magnetic tape is controlled by at least one magnetic head constituting the other magnetic head group of the two magnetic head groups. Difference between the output levels of the signals reproduced from two tracks separated by twice the track pitch at the time of recording a normal signal, or the difference between the output levels of the signals reproduced from the tracks scanned by the head. Detecting information on a relative height between the two magnetic head groups based on the output level; and Te, and a step of adjusting the relative height between said two sets of magnetic head groups, methods. 10. The step of adjusting the relative height includes determining an optimal offset signal to be applied to at least one of the pair of actuators in order to compensate for the relative height, from information on the relative height. Storing the optimum offset signal to at least one of the pair of actuator means during normal signal recording to compensate for a relative height between the magnetic head groups. The method of claim 9 comprising: 11. The step of detecting information relating to the relative height includes: controlling an actuator corresponding to the other magnetic head group so that a difference between output levels reproduced from the two tracks becomes zero; The method according to claim 9, further comprising detecting an offset signal being applied to the actuator at that time as information on the relative height. 12. The step of detecting information relating to the relative height includes applying the information to an actuator corresponding to the other magnetic head group when a reproduction output level from a track being scanned by the magnetic head is maximized. The method according to claim 9, comprising detecting the offset signal as information relating to the relative height. 13. The rotating head type magnetic recording / reproducing apparatus further comprises: a test surface provided for each of the two sets of magnetic head groups; and at least one sensor for detecting a height of the test surface. Storing the output of the sensor for each of the test surfaces at the completion of the step of adjusting the relative height between the two magnetic head groups; and recording a normal signal. The method according to claim 10, further comprising independently controlling the pair of actuators such that an output of the sensor detected for each of the test surfaces sometimes coincides with the stored sensor output. the method of. 14. The rotating head type magnetic recording / reproducing apparatus further comprises: a test surface provided for each of the two sets of magnetic head groups; and at least one sensor for detecting a height of the test surface. Storing the output of the sensor for each of the test surfaces when the step of adjusting the relative height between the two sets of magnetic heads is completed; and For each of the above, the output of the sensor when the magnetic head group provided with the test surface is displaced from the state in which the relative height adjustment is completed by an integral multiple of the track pitch during normal signal recording is stored. And, based on the sensor output stored for each of the test surfaces, for each of the test surfaces, the displacement of the sensor based on the height at the time when the relative height adjustment is completed. Calibrating an output curve, and, when recording a normal signal, the sensor output detected for each of the test surfaces is calculated based on a displacement-output curve calibrated for each of the test surfaces. Converting the relative height to the displacement based on the height at the time of completion of the relative height adjustment, and the difference between the detected displacement of the test surface,
Calculating the relative height deviation over time of the two magnetic head groups; and correcting the optimum offset signal applied to at least one of the actuators based on the calculated difference. The method of claim 10, comprising providing. 15. The step of detecting and storing the sensor output for calibrating a displacement-output curve of the sensor, comprising: for each of the two magnetic head groups, at least one magnetic head of the magnetic head group Controlling the running of the magnetic tape so that signals from two tracks separated by twice the track pitch at the time of normal signal recording are reproduced evenly. Displaced from the state, and in the process, at least one magnetic head of the magnetic head group uniformly reproduces signals of two tracks separated by twice the track pitch at the time of normal signal recording, and / or Or detecting and storing a sensor output when a reproduction output of a signal reproduced by at least one magnetic head of the magnetic head group is maximized. The method according to claim 14. 16. The rotating head type magnetic recording / reproducing apparatus, wherein: a plurality of test surfaces provided on each of the two sets of magnetic heads, each of which is separated by a predetermined height; At least one sensor for detecting a height of each of the plurality of test surfaces, wherein the relative height adjustment method comprises: for each magnetic head group, determining a relative height between the two magnetic head groups; Storing the output of the sensor for each of the plurality of test surfaces at the time of completion of the adjusting step; and for each of the magnetic head groups, one of the test surfaces based on the stored sensor output. Calibrating the displacement-output curve of the sensor based on the height at the time when the relative height adjustment is completed, and for each magnetic head group, when recording a normal signal, one of the test surfaces To Converting the detected sensor output into a displacement based on the height at the time of completion of the relative height adjustment, based on the calibrated displacement-output curve; and Calculating the difference between the displacement amounts of the head groups as a relative height shift over time of the two magnetic head groups; and applying the difference to the at least one of the actuators based on the calculated difference. Correcting the optimal offset signal. 17. The rotating head type magnetic recording / reproducing apparatus, wherein: a test surface provided for each of the two sets of magnetic head groups; at least one sensor for detecting a height of the test surface; A first reference surface provided on a bottom surface of the drum, and one or more second reference surfaces provided on the bottom surface of the rotary drum at a predetermined height from the first reference surface; Further comprising: detecting the output of the sensor for each of the first and second reference planes; and detecting the output of the first reference plane based on the detected sensor output. Calibrating a distance-output curve of the sensor based on a height, and the sensor output for each of the test surfaces is respectively set to the first reference based on the calibrated distance-output curve. Distance from plane Calculating the difference between the two magnetic head groups; storing the difference between the distances at the time of completing the step of adjusting the relative height between the two magnetic head groups; and detecting the difference during normal signal recording. Controlling the pair of actuators such that a difference in distance matches the difference in distance at the completion of the adjusting step. 18. A rotating head type magnetic recording / reproducing apparatus capable of adjusting a relative height between a pair of magnetic heads, comprising: a rotating drum; a pair of magnetic heads; A pair of actuators for respectively displacing the pair of magnetic heads in the track width direction; and one of the pair of magnetic heads, on a magnetic tape running a plurality of types of signals predetermined for each track. Means for cyclically recording in order to form a plurality of tracks; means for rewinding the magnetic tape after recording of the signal; and the other of the pair of magnetic heads separating a gap among the plurality of tracks. Means for controlling the running of the magnetic tape so that signals from two adjacent tracks are evenly reproduced, and a height adjustment mode in which the magnetic tape is controlled to run. A plurality of offset signals corresponding to the displacement of the actuator are prepared in advance, and the offset signals are sequentially applied to one of the pair of actuators corresponding to the one magnetic head to displace the one magnetic head. Means for detecting the output level of the signal reproduced from the one magnetic head, and an offset signal when the output level of the reproduced signal is maximum, between the pair of magnetic heads. Means for detecting as relative height information; and determining an optimum offset signal to be applied to at least one of the pair of actuators in order to adjust the relative height, from an offset signal as information relating to the relative height. Means for storing the optimum offset signal during normal signal recording. Means for applying a voltage to at least one of the actuators to adjust the relative height between the heads. 19. A test surface provided on each of the pair of magnetic heads, at least one sensor for detecting a height of the test surface, and the pair of magnetic heads by the relative height adjusting means. Means for storing the output of the sensor for each of the test surfaces at the time when the relative height between them has been adjusted; and the output of the sensor detected for each of the test surfaces at the time of normal signal recording. 19. The rotating head type magnetic recording / reproducing apparatus according to claim 18, further comprising: means for independently controlling the pair of actuators so as to match the stored sensor output. 20. A test surface provided on each of the pair of magnetic heads, at least one sensor for detecting a height of the test surface, and the pair of magnetic heads by the relative height adjusting means. Means for storing the output of the sensor for each of the test surfaces at the time when the relative height between them is adjusted; and relative to each of the test surfaces, the magnetic head provided with the test surface is relatively moved. Means for storing the output of the sensor when displaced by an integral multiple of the track pitch during normal signal recording from the state where the height adjustment is completed, and the sensor output stored for each of the test surfaces. Means for calibrating the displacement-output curve of the sensor based on the height at the time of completion of the relative height adjustment for each of the test surfaces based on the test surface, Each Is converted to a displacement amount based on the height at the time of completion of the relative height adjustment based on the displacement-output curve calibrated for each of the test surfaces. And a difference between the detected displacement amounts of the detected surface,
The apparatus further comprises: means for calculating a relative displacement of the pair of magnetic heads over time; and means for correcting the optimum offset signal applied to at least one of the actuators based on the calculated difference. Item 19. A rotary head type magnetic recording / reproducing apparatus according to Item 18. 21. A means for detecting and storing the sensor output for calibrating a displacement-output curve of the sensor, comprising: for each of the pair of magnetic heads, two adjacent magnetic heads separated by a gap by the magnetic head; Means for controlling the running of the magnetic tape so that signals from the tracks are evenly reproduced; and displacing the magnetic head from this state, and in the process, the two magnetic heads adjacent to each other with a gap therebetween 21. A means for detecting and storing a sensor output when a signal output from a track of the same type is reproduced evenly and / or when a reproduction output of a signal reproduced by the magnetic head is maximized. Rotary head type magnetic recording and reproducing apparatus. 22. A plurality of test surfaces provided on each of the pair of magnetic heads, each of which is separated by a predetermined height, and a height of each of the plurality of test surfaces of each of the pair of magnetic heads is detected. At least one sensor, and for each magnetic head, the output of the sensor for each of the plurality of test surfaces at the time when the relative height between the pair of magnetic heads is adjusted by the relative height adjusting means. Means for storing, for each magnetic head, a displacement of the sensor based on a height at the time of completion of relative height adjustment with respect to one of the test surfaces based on the stored sensor output. Means for calibrating the output curve, and for each magnetic head, at the time of normal signal recording, the sensor output detected for one of the test surfaces is calculated based on the calibrated displacement-output curve. Relative height Means for converting the height of the pair of magnetic heads into a displacement based on the height at the time of completion of the adjustment; 19. The rotating head type magnetic recording / reproducing apparatus according to claim 18, further comprising: means for calculating as; and means for correcting the optimum offset signal applied to at least one of the actuators based on the calculated difference. . 23. A test surface provided on each of the pair of magnetic heads, at least one sensor for detecting a height of the test surface, and a first device provided on a bottom surface of the rotary drum. A reference surface; one or more second reference surfaces provided on the bottom surface of the rotary drum at a predetermined height from the first reference surface; and a first reference surface and a second reference surface. Means for detecting the output of the sensor for each; means for calibrating a distance-output curve of the sensor based on the height of a first reference plane based on the detected sensor output; Means for converting the sensor output for each of the test surfaces into a distance from the first reference surface based on the calibrated distance-output curve, and calculating the difference, and the relative height adjusting means The pair of magnetic heads Means for storing the difference in the distance at the time when the relative height is adjusted, and the difference in the distance detected at the time of recording the normal signal matches the difference in the distance when the adjustment of the relative height is completed. 19. The rotating head type magnetic recording / reproducing apparatus according to claim 18, further comprising: means for controlling the pair of actuators. 24. A rotating head type magnetic recording / reproducing apparatus capable of adjusting a relative height between two magnetic head groups, comprising: a rotating drum; and n (n is an integer of 2 or more) magnetic members. A pair of actuators attached to the rotating drum and displacing the two sets of magnetic head groups in the track width direction; and adjusting the relative height when adjusting the relative height. The number of revolutions is set to k times (k is a divisor of n other than 1) times the number of revolutions during normal recording / reproduction, or the running speed of the magnetic tape is set to 1 / k times the running speed during normal recording / reproduction. Means for setting, and at least one magnetic head constituting one of the two magnetic head groups, a plurality of types of signals predetermined for each track, the rotation of the set rotary drum. Means for forming a plurality of tracks by cyclically recording in a predetermined order on the running magnetic tape at or at the set running speed of the magnetic tape, and winding the magnetic tape after recording the signal. Returning means, and at least one magnetic head constituting one magnetic head group of the two magnetic head groups, which is separated from the plurality of tracks by a distance twice a track pitch at the time of normal signal recording. Means for controlling the travel of the magnetic tape so that the signal is reproduced evenly from the tracks; and in a height adjustment mode in which the travel of the magnetic tape is controlled, the other magnetic head of the two sets of magnetic heads is controlled. At least one magnetic head constituting a head group is used to control two tracks of the plurality of tracks separated by a distance twice as long as a track pitch during normal signal recording. The offset applied to the actuator corresponding to the head when the output level difference of the signal reproduced from the head becomes zero or when the output level of the signal reproduced from the track scanned by the head becomes maximum. Means for detecting a signal as information relating to the relative height between the two magnetic head groups; and at least one of the pair of actuators for adjusting the relative height from an offset signal as information relating to the relative height. Means for determining an optimum offset signal to be applied to one of the magnetic head groups, and storing the optimum offset signal to be applied to at least one of the pair of actuator means during normal signal recording. Means for adjusting the relative height of the magnetic head. 25. A test surface provided in each of the two sets of magnetic head groups, at least one sensor for detecting the height of the test surface, and the two sets of magnetic fields by the relative height adjusting means. Means for storing the output of the sensor for each of the test surfaces at the time when the relative height between the head groups has been adjusted; and the sensor detected for each of the test surfaces during normal signal recording 25. The rotating head type magnetic recording / reproducing apparatus according to claim 24, further comprising: means for independently controlling the pair of actuators so that the output of the rotary sensor coincides with the stored sensor output. 26. A test surface provided on each of the two sets of magnetic head groups, at least one sensor for detecting the height of the test surface, and the two sets of magnetic fields by the relative height adjustment means. Means for storing the output of the sensor for each of the test surfaces at the time when the relative height between the head groups is adjusted; and a magnetic head provided with the test surface for each of the test surfaces Means for storing the output of the sensor when the group is displaced from the state where the adjustment of the relative height is completed by an integral multiple of the track pitch at the time of normal signal recording, and stored for each of the test surfaces Means for calibrating a displacement-output curve of the sensor, based on the height at the time of completion of relative height adjustment with respect to each of the test surfaces, based on the sensor output, The surface under test The sensor output detected for each is based on a displacement-output curve calibrated for each of the test surfaces, the displacement amount based on the height at the time of completion of the relative height adjustment And a difference between the detected displacement amounts of the test surface,
Means for calculating the relative height deviation of the two magnetic head groups over time; and means for correcting the optimum offset signal applied to at least one of the actuators based on the calculated difference. The rotating head type magnetic recording / reproducing apparatus according to claim 24, comprising: 27. A means for detecting and recording the sensor output for calibrating a displacement-output curve of the sensor, comprising: for each of the two magnetic head groups, at least one magnetic head of the magnetic head group. Means for controlling the running of the magnetic tape so that signals from two tracks separated by twice the track pitch at the time of normal signal recording are reproduced evenly; And / or when the at least one magnetic head of the group of magnetic heads uniformly reproduces signals of two tracks separated by a distance of twice the track pitch at the time of normal signal recording, and / or Means for detecting and storing a sensor output when a reproduction output of a signal reproduced by at least one magnetic head of the magnetic head group is maximized. Rotating head type magnetic recording and reproducing device. 28. A plurality of test surfaces provided on each of the two sets of magnetic head groups, each of which is separated by a predetermined height, and a height of a plurality of test surfaces of each of the two sets of magnetic head groups And at least one sensor for detecting each of the plurality of test surfaces at the time when the relative height between the two sets of magnetic heads is adjusted by the relative height adjusting means for each magnetic head group. Means for storing the output of the sensor; and for each magnetic head group, a height at the time of completion of relative height adjustment with respect to one of the test surfaces based on the stored sensor output. Means for calibrating the displacement-output curve of the sensor, and for each magnetic head group, the sensor output detected for one of the test surfaces at the time of normal signal recording is converted to the calibrated displacement- Based on the output curve Means for converting the amount of displacement based on the height at the time of completion of the relative height adjustment, and a difference between the detected amounts of displacement of the two sets of magnetic head groups by the two sets of magnetic head groups. 25. The rotation according to claim 24, further comprising: means for calculating a relative height shift over time; and means for correcting an optimal offset signal applied to at least one of the actuators based on the calculated difference. Head type magnetic recording / reproducing device. 29. A test surface provided on each of the two sets of magnetic heads, at least one sensor for detecting a height of the test surface, and a first device provided on a bottom surface of the rotating drum. And one or more second reference surfaces provided on the bottom surface of the rotating drum at a predetermined height from the first reference surface; and the first and second reference surfaces Means for detecting the output of the sensor for each of the following; and means for calibrating a distance-output curve of the sensor based on the height of the first reference plane based on the detected sensor output; Means for converting the sensor output for each of the test surfaces into a distance from the first reference surface based on the calibrated distance-output curve and calculating the difference, and the relative height adjusting means The two sets of magnetic heads Means for storing the difference in the distance at the time when the relative height between the groups is adjusted; and the difference in the distance detected at the time of recording the normal signal is the value of the distance when the relative height adjustment by the adjusting means is completed. 25. The rotating head type magnetic recording / reproducing apparatus according to claim 24, further comprising: means for controlling the pair of actuators so as to match the difference.