JPH09305944A - Rotary head drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly extend a life of a rotary magnetic head by moving a dummy head prior to a plurality of rotary magnetic heads thereby to smooth a magnetic face of a magnetic tape and deteriorating a grinding force to the rotary magnetic heads by the magnetic face of the magnetic tape. SOLUTION: Fine projections and recesses 2b of magnetic particles are formed at a magnetic face 2a of a magnetic tape 2, which grind sliding faces 3a, 4a, 5a of a plurality of rotary magnetic heads 3, 4, 5. A dummy head 6 is slid on the magnetic face 2a prior to the plurality of rotary magnetic heads 3, 4, 5, whereby the magnetic particles are crushed and front ends of the fine projections and recesses 2b are cut. The magnetic face 2a is accordingly turned to a smooth face 2c. When the magnetic face 2a becomes the smooth face 2c, a grinding force to the sliding faces 3a, 4a, 5a of the plurality of rotary magnetic heads 3, 4, 5 by the magnetic face 2a is deteriorated, and therefore the abrasion of the sliding faces 3a, 4a, 5a is reduced. A life of each head 3, 4, 5 is thus extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head suitable for application to a magnetic recording / reproducing apparatus for recording and / or reproducing a signal on a magnetic tape by a helical scan system such as a video tape recorder, a data recorder, a tape streamer and the like. It belongs to the technical field of drums.

[0002]

2. Description of the Related Art Conventionally, in a magnetic recording / reproducing apparatus for recording and / or reproducing a signal on a magnetic tape by a helical scan system such as a video recorder, a data recorder, a tape streamer, etc., a plurality of recording, reproducing, erasing, etc. Is equipped with a rotary head drum having a rotary magnetic head, and while the magnetic tape is wound around the outer circumference of the rotary head drum in a helical shape for running, the magnetic surface of the magnetic tape is signaled by a helical scan method by a plurality of rotary magnetic heads. Are recorded and / or reproduced.

[0003]

By the way, since the magnetic surface of the magnetic tape has fine irregularities of magnetic powder, the magnetic tape and the plurality of rotary magnetic heads are slid relative to each other by the relative sliding action. The tape and the plurality of rotating magnetic heads are mutually abraded. At this time, in the rotary head drum,
The amount of wear of the rotary magnetic head, which is rotated in contact with the magnetic tape in advance, tends to increase. However, magnetic tape is a consumable item and can be easily replaced, but since multiple rotary magnetic heads are troublesome to replace and maintenance costs are extremely high, extending the life of the rotary magnetic head is the most important issue. Has become. The characteristic B in the graph showing the relationship between the usage time and the wear rate of the rotary magnetic head shown in FIG. 5 indicates the wear amount of the preceding rotary magnetic head in the conventional rotary head drum, 1,600
The amount of protrusion of the preceding rotary magnetic head (which is the amount of protrusion of the tape contact surface of the rotary magnetic head protruding outward from the outer peripheral surface of the rotary head drum) is worn down to a life value of about 19 μm with the use of time. It means that there is.

Therefore, conventionally, in order to extend the life of the rotary magnetic head, the contact width of the rotary magnetic head with respect to the magnetic tape is increased, and the wear resistance of the material of the rotary magnetic head is increased. Although various measures have been taken such as lowering the tension of the magnetic tape, if the contact width of the rotary magnetic head is increased, spacing loss increases and output decreases. Increasing the wear resistance of the material of the rotary magnetic head reduces the output. Increasing the tension of the magnetic tape increases the spacing loss and lowers the output, which is not an effective means for balancing the wear resistance of the rotary magnetic head and the output.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce the wear of the rotary magnetic head without adversely affecting the output of the rotary magnetic head. It is intended to provide a rotating head drum.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, a rotary head drum of the present invention comprises a dummy head which is arranged so that the magnetic surface of a magnetic tape is smoothed prior to a plurality of rotary magnetic heads. Be prepared.

In the rotary head drum of the present invention constructed as described above, since the dummy head smoothes the magnetic surface of the magnetic tape prior to the plurality of rotary magnetic heads, the rotary magnetic field generated by the magnetic surface of the magnetic tape. The polishing power of the head can be deteriorated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary head drum in a magnetic recording / reproducing apparatus to which the present invention is applied will be described below with reference to the drawings.

First, as shown in FIGS. 2 to 4, the magnetic tape 2 is helically wound around the outer periphery of the rotary head drum 1 so that the magnetic tape 2 travels. The rotation direction of 1 (the direction of arrow a) and the running direction of the magnetic tape 2 (the direction of arrow b) are configured in the forward direction (however, they may be in the opposite direction). A plurality of rotary magnetic heads 3, 4, 5 for recording and / or reproducing various signals are attached to the magnetic surface 2a of the magnetic tape 2. Here, the plurality of rotary magnetic heads 3, 4 are attached. 5 shows a schematic structure in which a recording head 3 and a reproducing head 4 of two channels having different azimuths and one erasing head 5 are provided. Then, on the outer circumference of the rotary head drum 1, a dummy head for smoothing the magnetic surface 2a of the magnetic tape 2 ahead of the plurality of rotary magnetic heads 3, 4, 5 (however, signal recording, A head 6 which is not involved in reproduction and erasing at all is attached. Each of the plurality of rotary magnetic heads 3, 4 and 5 is provided with a head chip in which a coil 8 is wound around a head core 7 made of a ferromagnetic material such as ferrite, and the dummy head 6 is also composed of the head core 7 such as ferrite. ing.

By the way, as the rotary head drum 1,
There are two methods, an upper rotating drum method and a middle rotating drum method. The plurality of rotating magnetic heads 3, 4, 5 and the dummy head 6 are attached to a head rotating member such as the upper rotating drum and the middle rotating drum. However, the plurality of rotary magnetic heads 3, 4, 5 and the dummy head 6 are not included in the rotary head drum 1.
Reference head height position P perpendicular to the rotation center line P ₁ of
Mounted along format ₂ with spacing and height defined by the format. At this time, the dummy head 6 is arranged at the most preceding position on the upstream side (the arrow a direction side) of the rotary head drum 1 in the rotation direction.
The erasing head 5, the two-channel recording head 3 and the reproducing head 4 toward the downstream side (arrow a'direction side) in the rotation direction of the.
Are arranged in this order.

Here, referring to FIG. 3, the tape sliding surface 3 of the plurality of rotary magnetic heads 3, 4, 5 and the dummy head 6 is shown.
An example of the contact width (contact width) of a, 4a, 5a and 6a with respect to the magnetic tape 2 and the height with respect to the reference head height position P ₂ will be described. First, the contact widths W ₁ and W ₂ of the two-channel recording head 3 and the reproducing head 4 are both set to 100 μm, the contact width W ₃ of the erase head 5 is set to 110 μm, and the contact width of the dummy head 6 is set. The width W ₄ is, for example, 200 μm. Then, with reference to one preceding recording head 3, another succeeding recording head 3 has a track pitch defined by the format with respect to the reference head height position P ₂ (for example, the track pitch in the digital mode is 32 μm). Is set to a height H ₁ (for example, about 29.7 μm) capable of forming a recording medium, and the two reproducing heads 4 have two channels of different azimuth recorded on the magnetic surface 2a of the magnetic tape 2 by the recording head 3 of two channels. The recording data (recording track) is transferred from the steady running of the magnetic tape 2 to the high speed running (for example, 4
A predetermined height H ₂ (for example, 29.6) with respect to the reference head height position P ₂ so that reproduction can be performed at all speeds up to double speed.
μm) and H ₃ (for example, 1.2 μm). The erasing head 5 is set at a position higher than the reference head height position P ₂ by a predetermined height H ₄ (for example, 300 μm) so as to precede the two recording heads 3. Then, the dummy head 6 precedes the plurality of rotary magnetic heads 3, 4, 5 so that the magnetic surface 2a of the magnetic tape 2 can be smoothed several times so that the reference head height position P Specified height H ₅ for ₂
It is set at a high position (for example, 535 μm).

According to the rotary head drum 1 of the present invention configured as described above, a plurality of rotary magnetic heads 3, 4, and 5 are provided to the magnetic tape 2 running in the direction of the arrow b.
By rotating helically in the direction, it is possible to record and / or reproduce various signals on the magnetic surface 2a of the magnetic tape 2. At this time, the dummy head 6 causes the dummy head 6 to rotate the plurality of rotary magnetic heads 3, 4 ,. 5, the magnetic surface 2a of the magnetic tape 2 is smoothed evenly, and the tape sliding surfaces 3a, 4a, 5a of the plurality of rotary magnetic heads 3, 4, 5 by the magnetic surface 2a. Has deteriorated the polishing power.

That is, as shown in FIG. 1, the magnetic surface 2a of the magnetic tape 2 has fine irregularities 2b of magnetic powder, and the fine irregularities 2b form a plurality of rotary magnetic heads 3, 4, 5, 5.
The tape sliding surfaces 3a, 4a, 5a of 1 are polished. Therefore, when the dummy head 6 is slid on the magnetic surface 2a in advance of the plurality of rotary magnetic heads 3, 4, 5, the magnetic powder is crushed and the tips of the fine irregularities 2b are scraped off, and the magnetic properties thereof are removed. The surface 2a is leveled with the smooth surface 2c. Then, when the magnetic surface 2a is leveled with the smooth surface 2c, the tape sliding surfaces 3a, 4a, 5a of the rotary magnetic heads 3, 4, 5 by the magnetic surface 2a.
The polishing power of the tape is deteriorated, and these tape sliding surfaces 3a, 4
The wear of a and a is reduced, and the head life of the plurality of rotary magnetic heads 3, 4, and 5 is extended. However,
Even if the dummy head 6 flattens the magnetic surface 2a of the magnetic tape 2, recording and / or recording by the plurality of rotary magnetic heads 3, 4, and 5 are performed.
Or, there is no adverse effect such as output reduction during reproduction.

At this time, since the dummy head 6 does not participate in recording, reproducing and erasing signals at all, the contact width W ₄ of the dummy head 6 can be freely set. In this example, the track pitch 4 of the recording head 3 of 2 channels is set to 32 μm in the digital mode, and in the case where the rotary head drum 1 advances 64 μm in the track pitch direction with one rotation, the contact width of the dummy head 6 is about 3 200μ double
Since it is set to m, the dummy head 6 can slide on the same surface of the magnetic surface 2a of the magnetic tape 2 three times prior to the recording head 3. Then, in the experimental results of this example, as indicated by the characteristic A in the graph showing the relationship between the usage time and the wear rate of the rotary magnetic head shown in FIG. 5, the protrusion amount of the preceding rotary magnetic head was about 19 μm. Approximately 2,500 hours or more are required to reach the life value, and characteristic B
It has been found that the life of the head has been extended to about 1.6 times the conventional wear rate shown in.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea of the present invention.

[0016]

The rotary head drum of the present invention constructed as described above has the following effects.

According to the first aspect of the present invention, the dummy head smoothes the magnetic surface of the magnetic tape prior to the plurality of rotary magnetic heads to deteriorate the polishing force of the rotary magnetic head due to the magnetic surface of the magnetic tape. Therefore, it is possible to reduce the wear rate of a plurality of rotary magnetic heads and significantly increase the life of these rotary magnetic heads without adversely affecting the output, and to reduce maintenance costs such as head replacement. It can be significantly reduced.

According to a second aspect of the present invention, the contact width of the dummy head with respect to the magnetic tape is set to be larger than the contact width of each of the plurality of rotary magnetic heads with respect to the magnetic tape. It is possible to smooth evenly over the time, it is possible to effectively deteriorate the polishing force of the rotary magnetic head due to the magnetic surface of the magnetic tape, and it is possible to effectively increase the life of the head.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining an operation of leveling a magnetic surface of a magnetic tape by a dummy head in explaining an embodiment of a rotary head drum in a magnetic recording / reproducing apparatus to which the present invention is applied.

FIG. 2 is a bottom view showing an arrangement example of a plurality of rotary magnetic heads and dummy heads mounted on the outer periphery of a rotary head drum.

FIG. 3 is a development view illustrating a contact width of a plurality of rotary magnetic heads and a dummy head with respect to a magnetic tape and a height with respect to a reference head height position.

FIG. 4 is a schematic diagram illustrating a helical scan method of a magnetic tape by a plurality of rotary magnetic heads of a rotary head drum.

FIG. 5 is a graph showing the relationship between the wear time and the usage time of the preceding rotary magnetic head measured in the present invention and the conventional example.

[Explanation of symbols]

1 is a rotary head drum, 2 is a magnetic tape, 2a is a magnetic surface, 2b is fine unevenness, 2c is a smooth surface, 3, 4 and 5 are rotary magnetic heads, 3a, 4a and 5a are sliding tapes of the rotary magnetic head. Surface, 6 is a dummy head, 6a is a tape sliding surface of the dummy head, W ₁ , W ₂ and W ₃ are contact widths of the rotary magnetic head, W ₄ is contact width of the dummy head, and P ₂ is a reference head height position. Is.

Claims (2)

[Claims] 1. A rotary head drum provided with a plurality of rotary magnetic heads for recording and / or reproducing signals on a magnetic tape by a helical scan method, wherein a magnetic surface of the magnetic tape is placed before the plurality of rotary magnetic heads. A rotary head drum, which is provided with a dummy head that is smoothed and leveled. 2. The rotary head drum according to claim 1, wherein the contact width of the dummy head with respect to the magnetic tape is set to be larger than the contact width of each of the plurality of rotary magnetic heads with respect to the magnetic tape.