JP2000268452A - Magnetic recording / reproducing device and its rotating magnetic head device - Google Patents

Abstract

(57) Abstract: A magnetic head is in sufficient contact with a magnetic tape having high rigidity to achieve good recording / reproducing and reduce a change with time. A tension T of a magnetic tape 5 at the entrance of a rotary drum is provided.
i (gf) is set to Ti ≧ 0.4 × D × W / 12.7, and the tension Ti is set to 30 (gf) or more.
Is set to be the core 2i on the rear side in the drum rotation direction with respect to the magnetic gap 2g, and the radius of curvature of the R shape of the magnetic head surface in the rotation direction is 8 (mm).
Set to １３13 (mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus called a video tape recorder (VTR) having a helical scan type rotary magnetic head device and a rotary magnetic head device thereof.

[0002]

2. Description of the Related Art As described in Japanese Patent Publication No. 1-53958, there has been proposed a rotary magnetic head device in which the arrangement of a magnetic head and the track width are improved for multiple speed reproduction. However, in the conventional rotary head device, the contact portion between the magnetic head and various magnetic tapes is insufficiently considered, and the contact tends to be incomplete at the start of the magnetic tape contact of the rotary magnetic head. In particular, there is a problem that a poor contact is likely to occur with a magnetic tape having a high rigidity, and the contact failure progresses when the tape is run for a long period of time.

A magnetic recording / reproducing apparatus using a conventional helical scan type rotary magnetic head device will be described below. First, a general basic configuration of a rotary magnetic head device of a helical scan type VTR will be described with reference to FIGS.

FIG. 2 is a plan view of the rotary magnetic head device. The rotating drum 1 includes a first magnetic head 2a for video and a second magnetic head 2b for video at a position facing each other 180 degrees apart from each other, and is brought close to the first magnetic head 2a and the second magnetic head 2b, respectively. A third magnetic head for video 4b and a fourth magnetic head for video 4a are provided. Here, the first magnetic head 2a and the third magnetic head 4b which are close to each other
Is a double azimuth head 200, and the combination of the adjacent second magnetic head 2b and fourth magnetic head 4a is the double azimuth head 100.

[0005] The rotary drum 1 further includes a sound magnetic head 3a and a sound magnetic head 3b having azimuth angles different from those of the first to fourth magnetic heads at positions opposed to each other by 180 degrees. Ti indicates the magnetic tape tension at the beginning of the magnetic tape contact of the rotating magnetic head, ie, at the entrance of the rotating drum, and To indicates the magnetic tape tension at the end of the magnetic tape contacting the rotating magnetic head, ie, at the exit of the rotating drum. ing.

FIG. 3 is a front view of the rotary magnetic head device. The magnetic tape 5 is regulated by the guide rollers 9a and 9b and the fixed posts 10a and 10b, and
And fixedly wound diagonally around the fixed drum 8, and travels in the direction of arrow 7 along the magnetic tape lower end guide step 8 a provided on the outer periphery of the fixed drum 8, and the magnetic heads 2 a, 4 b
(2b, 4a, 3a, 3b) scans obliquely to perform magnetic recording and reproduction.

FIG. 4 is an envelope waveform diagram of a reproduction output signal output from the magnetic heads 2a and 2b, and shows a period of two fields (for one rotation of the rotating drum).

The magnetic heads 2a and 2b start to contact the magnetic tape 5 at the position 14 where the magnetic tape comes into contact. This portion is where the magnetic tape 5 starts to wind around the rotary drum 1 and the tape tension Ti is weak. In addition, the contact pressure P between the magnetic heads 2a and 2b and the magnetic tape 5 is weak, and the signal reproducing action tends to be weak. In particular, a highly rigid magnetic tape 5
Then, it was easy for poor contact. This phenomenon is called FM drop, and the evaluation method is that the output level 15 of the flat portion of the envelope waveform 13 of the reproduced output signal is set to 3.0, and the FM drop output level 16 at the entrance 14 of the magnetic tape contact start portion is set. S and 3.0: S. And 3.
If 0: 2.0 or more, there is no practical problem.

Further, there is a problem that the FM drop proceeds during a long tape running. However, the relationship between the tension Ti of the magnetic tape 5 at the entrance of the rotating drum and the change with time of the FM drop has not been investigated.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic head capable of sufficiently contacting a magnetic tape to perform magnetic recording / reproducing with little FM drop and to have a reliability with little change over time. It is an object of the present invention to provide a magnetic head device and a magnetic recording / reproducing device having high performance.

Another object of the present invention is to provide a magnetic head device and a magnetic recording / reproducing apparatus capable of performing magnetic recording / reproducing with less FM drop by sufficiently bringing the magnetic head into contact with a highly rigid magnetic tape. Is to do.

[0012]

SUMMARY OF THE INVENTION The present invention optimizes the tension Ti of a magnetic tape at the entrance of a rotating drum, the inclination of a core of a magnetic head projecting from the rotating drum, and the radius of curvature of the surface of the magnetic head. An object of the present invention is to provide a highly reliable magnetic head device capable of performing magnetic recording / reproducing with less FM drop by sufficiently bringing the surface of the magnetic head into contact with the magnetic tape, and having little change over time.

More specifically, a rotating drum and a fixed drum having substantially the same diameter are vertically arranged concentrically, and a plurality of magnetic heads are mounted on a lower end of the rotating drum. A helical scan type rotary magnetic head device for providing a guide portion for a reference edge of a magnetic tape, and performing magnetic recording and reproduction on the magnetic tape wound around a part of the outer peripheral surface of these drums using the magnetic head. In a magnetic recording / reproducing apparatus provided with
m), and when the diameter value of the rotating drum is D (mm), the tension Ti (gf) of the magnetic tape at the entrance of the rotating drum is Ti ≧ 0.4 × D × W / 12.7, and 25 (gf) The above is preferred.

Alternatively, a rotating drum and a fixed drum having substantially equal diameters are vertically arranged concentrically, and a plurality of magnetic heads are mounted on the lower end of the rotating drum. A helical scan type rotary magnetic head device for providing a guide portion for a reference edge of the tape and performing magnetic recording and reproduction on the magnetic tape in a state wound around a part of the outer peripheral surface of these drums using the magnetic head,
The plurality of magnetic heads are configured such that the largest protrusion of the magnetic heads with respect to the rotating drum is a core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic heads. By attaching the head base plate to the rotating drum in a state of being fixed to the rotating drum, the respective magnetic heads are provided so as to protrude from the surface of the rotating drum, and the attitude of these magnetic heads is inclined in the rotating direction of the drum. The maximum protrusion of the magnetic head with respect to the magnetic gap is a core on the rear side in the drum rotation direction with respect to the magnetic gaps of these magnetic heads, and the radius of curvature of the contact surface of the magnetic head with the magnetic tape in the rotation direction is set to 8 (Mm) to 13 (mm), or a rotating drum having a diameter value of 62 (mm) and a fixed drum are concentrically arranged vertically. A plurality of magnetic heads are mounted on the lower end of the rotating drum, and a guide portion for the reference edge of the magnetic tape is provided on the outer peripheral surface of the fixed drum, and the fixed drum is wound around a part of the outer peripheral surface of these drums. In a magnetic recording / reproducing apparatus having a helical scan type rotary magnetic head device for performing magnetic recording / reproducing on a magnetic tape having a width of 0.7 (mm) using a magnetic head, the tension of the magnetic tape at the entrance of the rotary drum is reduced to 30 ( gf) or more, so that the maximum protrusion of the magnetic head with respect to the surface of the rotary drum is set to be the core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic head, and the R shape of the surface of the magnetic head in the rotation direction is set. Is a curvature radius of 8 (mm) to 13 (mm).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The tension Ti of a magnetic tape 5 at the entrance of a rotary drum in a helical scan type rotary magnetic head device is generally set to be low. this is,
This is because applying a strong tension to the magnetic tape 5 causes a problem of wear of the magnetic tape and wear of the magnetic head during repeated running for a long time. Further, the tension To of the magnetic tape 5 at the outlet of the rotary drum increases due to running frictional resistance on the outer peripheral surface of the fixed drum 8. Therefore, if the tape tension To at the outlet of the rotating drum is suppressed to a certain value or less,
Since the tension Ti of the magnetic tape 5 at the entrance of the rotary drum needs to be set to a low value, the FM drop tends to be large.

The inventors conducted an experiment on the contact between the magnetic head and the magnetic tape with respect to the tension T of the magnetic tape in the helical scan type rotary magnetic head device, and obtained the first data shown in FIG. . FIG. 5 shows the magnetic tape tension Ti (g) at the entrance of the rotary drum on the horizontal axis.
Take f), take the FM drop output level on the vertical axis,
The measured value is represented by a white point. The experimental conditions are as follows: the diameter of the rotating drum is 62 mm, and the width of the magnetic tape is 12.7 mm. According to this data, the tension Ti of the magnetic tape is
It can be seen that a good envelope waveform can be obtained with 25 gf or more. The tension Ti of such a magnetic tape can be set by adjusting a force (spring force of a tension arm) for controlling a tension band that gives a back tension to the magnetic tape that is wound around the tape supply reel table and pulled out from the cassette. it can.

Considering the above first data, the following equation is established.

The contact pressure P of the magnetic tape applied to the magnetic head is proportional to the tension T (Ti, To) of the magnetic tape, the diameter D (mm) of the rotating drum and the width W of the magnetic tape.
(Mm), P = k × T / (D × W) holds (k is a coefficient). Assuming that the necessary contact pressure applied to the magnetic head is Pn, from the results of the experiment, Pn = k ×
T / (D × W) = k × 25 / (62 × 12.7), and if the necessary magnetic tape tension is Tn, Tn =
(25 × D × W) / (62 × 12.7). Thus, the range of the tension required for the magnetic tape at the entrance of the rotating drum is Ti ≧ 0.4 × D × W / 12.7.

FIG. 6 is an enlarged simulation diagram of a portion where the magnetic head starts to contact the magnetic tape. FIG.
FIG. 2 is an enlarged view of a conventional double azimuth head 200, in which a magnetic head 2 and a magnetic head 4 are integrally mounted on a rotating drum 1. The core of each head of the double azimuth head 200 is called an i-core and a c-core because the shape is similar to the alphabets i and c.

The core of the video head 2 is a head i-core 2
i and a head c core 2c, and a video head 4
Are constituted by a head i-core 4i and a head c-core 4c. 2g is a magnetic gap of the video head 2, and 4g is a magnetic gap of the video head 4.

In FIG. 6, the shape of the magnetic tape 5 at an appropriate tape tension is as shown by reference numeral 5a, and the shape as shown by reference numeral 5b at a weak tape tension due to the rigidity of the magnetic tape 5. Become. In particular, it is clear that such a tape shape is obtained from the fact that the FM drop is large in the magnetic tape 5 having high rigidity. When the tape is run for a long time with a weak tape tension, the head i
The wear of the core 2i and the head i core 4i proceeds rapidly, and the radius of curvature R at the tip of the magnetic head increases. This is uneven wear that has been locally worn and, although hypothesized, causes an increase in FM drop.

Next, the inventors focused on the shape of the magnetic tape contact surface of the magnetic head, particularly the apex position of the head, conducted an experiment on FM drop, and obtained the second data as shown in FIG. Was. This is correlation data between the magnetic head apex position (L) and the entry FM fall output level (3.0: S).

Before describing the data of FIG. 8, the state of contact between the conventional double azimuth head 200 and the magnetic tape 5 shown in FIG. 7 will be described. FIG. 7A is an enlarged view of a conventional double azimuth head 200. The magnetic head 2 and the magnetic head 4 are fixed on a head base plate 200b, and the outer peripheral surface of the rotary drum 1 of the magnetic heads 2 and 4, respectively. The protrusion 2p and the head protrusion 4p are integrally provided on the rotary drum 1 such that the protrusion amount is substantially equal to the head protrusion amount 4p and a predetermined protrusion amount.

FIG. 7B is a view taken in the direction of arrow A in FIG. 7A (an enlarged view of the surface of the magnetic head). The magnetic gaps 2g and 4g of the magnetic heads 2 and 4 are observed from directly in front with an interference microscope. FIG. Regarding the magnetic head 2, irregularities on the head surface are represented by interference fringes 12. This interference fringe 1
The center of 2 is the most convex, and is the head vertex 11p.

In FIG. 7B, the position of the head vertex 11p is located on the head c core 2c.
Here, from the head magnetic gap 2g to the head vertex 11p
Up to L, and based on the magnetic gap 2g,
If the c-core side is plus and the i-core side is minus,
The double azimuth head uses the head core 20
Since the final finish polishing is performed after fixing on Rb, the R shape is integrated, and the average value of L is usually on the minus side. However, since the head protrusion amount 2p is substantially equal to the head protrusion amount 4p, the value of L is also distributed on the plus side due to an error in the mounting accuracy of the head base plate 200b.

FIG. 8 shows a measured result obtained by recording and reproducing using a magnetic tape having a low magnetic tape tension Ti (gf) and a high rigidity. The head apex position (L) and the entry-side FM drop output level (3 .0: S). The horizontal axis indicates the head apex position, and the vertical axis indicates the side FM drop output level. From this data, it can be seen that some of the magnetic tapes having a high rigidity have a low entry FM drop output level (3.0: S). Considering this data, the head vertex position (L)
It can be seen that if the value is negative, the input FM drop output level (3.0: S) increases and good characteristics can be obtained.

On the other hand, if the head vertex position (L) is on the plus side, the entry-side FM fall output level (3.0: S) is low. This fact means that the head apex position (L) moves due to the above-mentioned phenomenon (uneven wear of only the head i-core), and the FM drop may increase with time.

The inventors further focused on the curved shape (surface R = radius of curvature) of the magnetic tape contact surface on the surface of the magnetic head, and conducted an experiment on FM drop to obtain the second shape as shown in FIG. 3 data were obtained. In FIG. 9, the horizontal axis indicates the magnetic head surface R, and the vertical axis indicates the FM drop output level. The experimental conditions were
The diameter of the rotating drum is 62 mm, and the width of the magnetic tape is 12.
7 mm. Considering this data, it is clear that the surface R of the magnetic head is preferably 13 mm or less (entrance FM).
If the falling output level is 3.0: 2.0 or more, there is no practical problem). The fact that the magnetic head surface R drops FM when it is 14 mm or more also matches the phenomenon described above (FM drop due to uneven wear in which the curvature R is increased only at the head end), and confirms that the FM drop occurs.

The inventors further conducted an experiment on the change over time of the tension Ti and the FM drop of the magnetic tape at the entrance of the rotary drum. The result is shown in FIG. When the tension of the magnetic tape at the entrance of the rotating drum is 30 (gf) or more, it can be seen that the change with time of FM drop is very small. Also, when the tension Ti of the magnetic tape is weak, the change with time of the FM drop is large,
It can be confirmed that the hypothesis that uneven wear occurs due to tape running with a weak tape tension is correct. Incidentally, the upper limit of the tension Ti of the magnetic tape at the entrance of the rotary drum is set at 4 to avoid the problem of the elongation of the magnetic tape.
5 (gf) or less is preferable.

As described above, in order to achieve the object of the present invention, it is desirable to adopt the following structure by investigating the relationship between the tension of the magnetic tape at the entrance of the rotary drum and the change with time of the FM drop.

(1) A rotating drum and a fixed drum having substantially the same diameter are vertically arranged concentrically, a plurality of magnetic heads are mounted at the lower end of the rotating drum, and a magnetic tape is provided on the outer peripheral surface of the fixed drum. A magnetic portion provided with a helical scan type rotary magnetic head device for performing magnetic recording and reproduction on the magnetic tape wound around a part of the outer peripheral surface of these drums using the magnetic head. In a recording / reproducing apparatus, generally, the width of a magnetic tape is set to W (m
m), and the tension Ti (gf) of the magnetic tape at the entrance of the rotary drum when the diameter value of the rotary drum is D (mm) is set to Ti ≧ 0.4 × D × W / 12.7. 25
(Gf) to 45 (gf) are desirable.

(2) In the rotary magnetic head device,
Preferably, the plurality of magnetic heads are set such that the largest protruding portion is a core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic head.

(3) In the rotary magnetic head device,
Preferably, the plurality of magnetic heads are arranged such that the maximum projection of the magnetic head with respect to the rotating drum is inclined with respect to the magnetic gap of these magnetic heads in the drum rotation direction by tilting the attitude of these magnetic heads in the drum rotation direction. Set so that

(4) The radius of curvature of the surface of the magnetic head in contact with the magnetic tape in the rotational direction is set to a radius of curvature of 8 (mm) to 13 (mm).
(Mm).

(5) In the rotary magnetic head device,
In a magnetic recording / reproducing apparatus provided with a helical scan type rotary magnetic head device for performing magnetic recording / reproducing using a magnetic head by winding a magnetic tape having a width of 12.7 (mm) around a drum having a diameter value of 62 (mm), The tension of the magnetic tape at the entrance of the rotary drum is set to 30 (gf) or more, and the maximum protrusion of the magnetic head with respect to the surface of the rotary drum is set to be the core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic head. The R shape in the rotational direction of the surface of the magnetic head is set to 8 (mm) to 13 (mm).

FIG. 1 shows a specific embodiment of the rotary magnetic head device according to the present invention constructed in consideration of such considerations. FIG. 1A is an enlarged view of a double azimuth head portion in this embodiment, and FIG. 1B is an enlarged view of an arrow B in FIG.

FIG. 1A shows that the back tension mechanism is set so that the tension Ti of the magnetic tape 5 at the entrance of the rotary drum is 30 (gf) or more, and the two magnetic heads 2 and 4 which are close to each other are made the same. The two magnetic heads 2 and 4 are tilted by θ degrees in the direction of rotation of the drum as a whole are arranged side by side with the head base plate 200a and attached to the rotating drum 1 by tilting the head base plate 200a by θ degrees. It was done.

By doing so, the magnetic head 2
Becomes the core 2i on the rear side in the drum rotation direction with respect to the magnetic gap 2g of the magnetic head 2,
As shown in FIG. 1B, the head vertex 11m is on the minus side. The radius of curvature of the R shape in the rotation direction of the surfaces of the magnetic heads 2 and 4 was set to 8 (mm) to 13 (mm).

[0039]

According to the present invention, the following effects can be obtained.

(1) The width of the magnetic tape is W (mm),
When the diameter value of the rotating drum is D (mm), the tension Ti (gf) of the magnetic tape at the entrance of the rotating drum is Ti ≧ 0.
4 × D × W / 12.7, preferably 25 (gf) or more
By setting the value to 45 (gf), the magnetic head is sufficiently brought into contact with a normal magnetic tape, so that good magnetic recording and reproduction can be realized.

(2) The maximum projection of the magnetic head is disposed on the core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic head by arranging the magnetic head on the rotary drum while tilting it in the drum rotation direction. I set it to be
Even when the magnetic head is in sufficient contact with a magnetic tape having high rigidity, good magnetic recording and reproduction can be realized.

(3) The tension Ti of the magnetic tape at the entrance of the rotary drum is set to 30 (gf) or more so that the maximum protrusion of the magnetic head becomes the core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic head. And the radius of curvature of the R shape in the rotation direction of the magnetic head surface is set to 8 (mm) to 13 (m).
By setting m), the magnetic head can be brought into sufficient contact with a magnetic tape having high rigidity to realize good magnetic recording and reproduction, and change over time can be reduced.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of a rotary magnetic head device according to the present invention, in which FIG. 1A is an enlarged view of a double azimuth head portion, and FIG. 1B is an enlarged view of arrow B in FIG. )
It is.

FIG. 2 is a plan view showing a positional relationship of a head on a rotary drum having a general basic configuration of a helical scan type rotary magnetic head device.

FIG. 3 is a front view of the rotary magnetic head device shown in FIG. 2;

FIG. 4 is an envelope waveform diagram of a reproduction output signal from a video head.

FIG. 5 shows first data (entrance FM drop output with respect to magnetic tape tension Ti) obtained from an experiment conducted on contact between the magnetic head and the magnetic tape with respect to the magnetic tape tension T in the helical scan type rotary magnetic head device. Level).

FIG. 6 is an enlarged simulation diagram of a portion where the magnetic head starts to contact the magnetic tape.

7A and 7B are diagrams showing a state of contact between a conventional double azimuth head and a magnetic tape, wherein FIG. 7A is an enlarged view of a double azimuth head 200, and FIG. FIG.

FIG. 8 is experimental data showing a correlation between a head vertex position (L) and an entry-side FM drop output level (3.0: S).

FIG. 9 is experimental data showing a correlation between the surface R of the magnetic head and the output level of the falling-in FM.

FIG. 10 shows the tension and FM of the magnetic tape at the entrance of the rotating drum.
It is experimental data which shows the relationship of the time-dependent change of falling.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotary drum, 2 ... Magnetic head, 2a ... 1st magnetic head, 2b ... 2nd magnetic head, 2c ... Head c core, 2p
... Head protrusion amount, 2g ... Head magnetic gap, 2i ... Head i core, 3a, 3b ... Audio magnetic head, 4 ... Magnetic head, 4a ... Fourth magnetic head, 4b ... Third magnetic head, 4c ... Head c core , 4g ... head magnetic gap,
4i: Head i core, 4p: Head protrusion amount, 5: Magnetic tape, 5a: Magnetic tape shape at proper tape tension, 5b
... Magnetic tape shape at low tape tension, 6: Head moving direction, 7: Magnetic tape moving direction, Ti: Tape tension at the entrance of rotary drum, 8: Fixed drum, 8a: Magnetic tape lower end guide step, 9a, 9b: Guide Rollers, 10a, 10b ...
Fixed post, 11p: Head apex, 11m: Head apex, 12: Interference fringe, 13: Reproduced output signal envelope waveform, 14: Magnetic tape contact start position, 15: Flat part output level, 16: Input FM drop output level , 100 ...
Double azimuth head, 200: Double azimuth head, 200a, 200b: Head base plate.

Claims (6)

[Claims] 1. A rotating drum and a fixed drum having substantially the same diameter are vertically arranged concentrically, a plurality of magnetic heads are mounted on a lower end of the rotating drum, and a magnetic head is mounted on an outer peripheral surface of the fixed drum. A helical scan type rotary magnetic head device for providing a guide portion for a reference edge of the tape and performing magnetic recording and reproduction on the magnetic tape wound around a part of the outer peripheral surface of these drums using the magnetic head is provided. In the magnetic recording / reproducing apparatus, when the width of the magnetic tape is W (mm) and the diameter of the rotating drum is D (mm), the tension Ti (gf) of the magnetic tape at the entrance of the rotating drum is Ti ≧ 0.4 × D × W / 12.7. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the tension Ti of the magnetic tape at the entrance of the rotary drum is 25 (gf) or more. 3. A rotating drum and a fixed drum having substantially equal diameters are vertically arranged concentrically, a plurality of magnetic heads are mounted on a lower end of the rotating drum, and a magnetic head is mounted on an outer peripheral surface of the fixed drum. A helical scan type rotary magnetic head device for providing a guide portion for a reference edge of the tape and performing magnetic recording and reproduction on a magnetic tape wound around a part of the outer peripheral surface of these drums using the magnetic head, A rotary magnetic head device, wherein the plurality of magnetic heads have a maximum protrusion of the magnetic head with respect to a rotating drum, which is a core on the rear side in the drum rotation direction with respect to a magnetic gap of the magnetic head. 4. A magnetic head according to claim 3, wherein said plurality of magnetic heads are fixed to said head base plate, and said head base plate is attached to a rotating drum so that each magnetic head is provided so as to project from the surface of said rotating drum. By tilting the attitude of the magnetic head in the direction of rotation of the drum, the maximum protrusion of the magnetic head relative to the rotating drum becomes the core on the rear side in the drum rotation direction with respect to the magnetic gap of these magnetic heads. A rotating magnetic head device. 5. The rotary magnetic head device according to claim 3, wherein the radius of curvature of the surface of the magnetic head in contact with the magnetic tape in the rotational direction is 8 (mm) to 13 (mm). 6. A rotary drum having a diameter value of 62 (mm) and a fixed drum are concentrically arranged above and below, and a plurality of magnetic heads are mounted at the lower end of the rotary drum. A guide portion for the reference edge of the magnetic tape is provided on the surface of the drum.
In a magnetic recording / reproducing apparatus having a helical scan type rotary magnetic head device for performing magnetic recording / reproducing on a magnetic tape having a width of 2.7 (mm) using a magnetic head, the tension of the magnetic tape at the entrance of the rotary drum is reduced to 30. (Gf) or more, so that the maximum protrusion of the magnetic head with respect to the surface of the rotary drum is set to be the core on the rear side in the drum rotation direction with respect to the magnetic gap of the magnetic head. The shape has a radius of curvature of 8 (mm) to 13 (m).
m) A magnetic recording / reproducing apparatus comprising a rotary magnetic head device described in (m).