JPH07334897A - Rotary head drum device - Google Patents

Abstract

PURPOSE:To attain a high density recording, high data rate recording and editing in a drum unit rotating at a high speed by improving the running performance of tape. CONSTITUTION:A 1st fixed drum 21 provided with a tapered part 26 on the tape running surface and a 2nd fixed drum 22 provided with a lead 23 are almost coaxially arranged so as to be opposed to each other, and a middle drum 25 mounting a magnetic head 24 is freely rotatably provided between them. In at least the neighborhood of the center of the tape winding part, the distance R2 from the rotation center of the middle drum to the lowermost end C2 of the outer peripheral surface of the fixed drum 21 is made shorter than the distance R1 to the uppermost end C1 of the outer peripheral surface of the middle drum. When the tape 27 runs along the drums 21, 22, 25 by this arrangement, the tape 27 is made to run along the lead 23 by receiving the force toward the 2nd fixed drum, even though it is deviated upward from the fixed drum 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head drum device used in a VTR or DAT for recording at high recording density and high data rate.

[0002]

2. Description of the Related Art Conventionally, magnetic recording / reproducing apparatuses such as VTRs (VHS (registered trademark) system video tape recorders) and DATs (digital audio tape recorders) have been used.
It has a rotating upper drum and a fixed drum provided with a lead for guiding the running of a magnetic tape (hereinafter referred to as tape), and tape guide rollers for restricting the running position of the tape are provided before and after the drum. It is provided. But,
Even if such a tape guide mechanism is provided and the tape is regulated, the running of the tape is unstable in the tape width direction, and it is difficult to normally perform magnetic recording / reproduction when the recorded track width is narrow. There was a point.

As a method for solving such a problem,
Conventionally, various methods have been proposed. For example, Japanese Patent Application Laid-Open No. 52-28306 discloses a technique in which a large-diameter portion and a small-diameter portion are provided on an upper drum, and a tape is stably run by an air layer generated between the upper drum and the tape. There is.

By the way, recently, in the trend of digitization of video signals and high-density recording (HD), high data rate recording is often performed, and a large-diameter drum is used for widening the recording band. The technique used is to increase the number of rotations of the drum. However, increasing the relative speed of such a magnetic head with respect to the tape has resulted in an increase in the flying height of the tape, resulting in a loss of stability of tape running. As a countermeasure for this, the tape floating amount is reduced by using a drum device of the medium drum rotation method, but it is extremely difficult to secure the running performance of the tape on the lead because the drum has a large diameter. there were. Therefore, the tape guide roller that has been conventionally used has a large inclination angle and is adjusted so that the tape follows the lead of the drum to ensure the linearity of the track pattern.

Further, there is a problem that it is difficult to adjust the tape for stable running on the lead of the drum, and it is very difficult to achieve both flatness of the reproduced signal waveform and linearity of the track pattern. there were. Further, since the running adjustment is performed unreasonably, there is a problem that the tape is likely to be damaged when the tape is repeatedly run. A conventional countermeasure method for such a problem will be described with reference to FIG.

FIG. 6 is a side view showing the structure of a conventional drum unit. As shown in the figure, the rotary shaft 3 of the rotary drum 2 on which the magnetic head 1 is mounted and the fixed drum 5 on which the leads 4 are formed are arranged coaxially. The rotation of the rotary drum 2 causes the magnetic head 1 to record and reproduce on the tape 6 running along the lead 4.

[0007]

When the number of rotations of the rotary drum 2 is increased, the tape 6 is lifted up by the air layer formed by the rotation of the magnetic head 1 and the rotary drum 2, and the tape 6 is read. You will drive away from 4. Due to this phenomenon, the linearity of the track deteriorates. Therefore, the height of the tape guide roller 7 provided in front of and behind the drum is lowered so that the tape 6 is forcibly adjusted along the lead 4. When the tape 6 is repeatedly run under such conditions, the tape is easily damaged, and it has been extremely difficult to simultaneously secure the linearity of the track and prevent the tape from being damaged.

The present invention has been made in view of the above conventional problems, and it stabilizes the running of the tape, and the rotary head drum device is excellent in the linearity of the track pattern and the stability of the recording / reproducing signal. The purpose is to supply.

[0009]

According to the invention of claim 1 of the present application, a first fixed drum and a lead for guiding the running of the tape are formed, and a second fixed drum is mounted coaxially with the first fixed drum. A rotary head drum device comprising: a fixed drum; and a middle drum rotatably mounted between a first fixed drum and a second fixed drum and having a magnetic head,
The first fixed drum has a taper portion whose outer diameter increases as the axial distance of the first fixed drum from the middle drum increases at least in the region where the tape of the first fixed drum travels in contact. The first fixed drum and the middle drum have a distance R1 from the rotation center of the middle drum to the uppermost end of the outer peripheral surface of the middle drum at least at the center of the winding angle of the tape. It is characterized in that it is attached so as to be larger than a distance R2 from the center of rotation to the lowermost end of the first fixed drum.

In the invention of claim 2 of the present application, the first fixed drum is characterized in that the surface roughness thereof is gradually roughened at least from the lower end side to the upper end side on the tape running surface.

In the invention of claim 3 of the present application, the first fixed drum forms a processing mark of a stripe line on the tape running surface so as to be parallel to the tape running direction, and in the area where the tape contacts and runs, It is characterized in that the surface roughness is increased as the distance from the drum increases.

According to the invention of claim 4 of the present application, the first fixed drum is characterized in that the surface roughness of the tape running surface is at least equal to or rougher than the surface roughness of the second fixed drum.

According to a fifth aspect of the present invention, the second fixed drum is characterized in that the surface roughness of the tape running surface is in the range of 0.1 μm to 1 μm.

[0014]

According to the invention of claim 1 of the present application having such a characteristic, at least in the region where the tape travels in contact with the first fixed drum, from the rotation center of the middle drum to the uppermost end of the outer peripheral surface of the middle drum. Since the distance R1 is larger than the distance R2 from the center of rotation of the middle drum to the bottom end of the first fixed drum, the tape strongly abuts the middle drum having the magnetic head. Further, since the first fixed drum has a taper portion whose outer diameter increases as the distance from the middle drum increases, the tape is wound around the outer peripheral surfaces of the middle drum and the first fixed drum. As the tape travels, the greater the rate at which the tape comes into contact with the upper portion of the first fixed drum, the greater the frictional force that it receives. Therefore, the tape acts to move downward in the middle drum, so that the tape runs along the lead of the second fixed drum. Therefore, the running load of the tape wound around each drum is reduced, and the running of the tape is stabilized.

Further, according to the invention of claim 2 of the present application, as the distance between the first fixed drum and the middle drum increases, the outer diameter becomes at least in the region where the tape travels in contact with the first fixed drum. Since the taper portion is formed to be large and the surface roughness of the first fixed drum is gradually roughened from the lower end side to the upper end side, a larger frictional force is applied to the upper portion of the tape. Therefore, the tape acts to move downward in the middle drum, and fluctuations in the width direction of the tape in the leads provided on the second fixed drum are reduced. This improves the linearity of the track pattern and reduces the fluctuation of the reproduction output.

Further, according to the invention of claim 3 of the present application, as the distance between the first fixed drum and the middle drum increases, the outer diameter becomes at least in the region where the tape travels in contact with the first fixed drum. Since the taper portion that increases in size is formed and the tape running surface of the first fixed drum is formed with a line-shaped processing mark that is parallel to the tape running direction, a greater frictional force is applied to the upper part of the tape. . For this reason, the tape easily runs along the leads provided on the second fixed drum, and the linearity of the track pattern is improved.

Further, according to the inventions of claims 4 and 5, the surface roughness of the second fixed tram is made smooth so that the sticking phenomenon of the tape does not occur in a humid environment. When the surface roughness of the first fixed drum is at least equal to or rougher than the surface roughness of the second fixed drum, the upper part of the tape receives a large frictional force and the lower part receives a small frictional force. The imbalance of these frictional forces causes the tape to move downward. Therefore, the tape easily runs along the lead, and the linearity of the track pattern is improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotary head drum device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a side view of a drum unit 20 in the rotary head drum device of the first embodiment. The drum unit 20 shown in the figure has a first fixed drum 21 located at the upper part, a second fixed drum 22 located at the lower part and provided with leads 23 for guiding tape running,
It is composed of a middle drum 25 which is located in the middle part and to which a magnetic head 24 is attached. On the outer periphery of the fixed drum 21, at least on the tape running surface, the taper portion 26 whose outer diameter increases as the distance from the middle drum 25 increases.
Are formed.

The fixed drum 21 and the fixed drum 22 are fixed from the outside of the drum unit 20 by a U-shaped connecting jig (not shown). Medium drum 25 is magnetic head 24
At the same time, it rotates between the fixed drum 21 and the fixed drum 22. The tape 27 runs along the leads 23 of the fixed drum 22 and contacts the magnetic head 24 slightly protruding from the outer peripheral surface of the middle drum 25, whereby recording and reproduction are performed.

Next, the positional relationship between the intermediate drum 25 and the fixed drum 21 will be described with reference to FIG. FIG. 2 conceptually shows the positional relationship between the uppermost end C1 of the outer peripheral surface of the middle drum 25 and the lowermost end C2 of the outer peripheral surface of the fixed drum 21. The distance from the center of rotation of the middle drum 25 to the uppermost end C1 is R1, and the distance from the center of rotation of the middle drum 25 to the lowermost C2 is R2. Further, the tape winding angle of the drum unit 20 is set to θ. The center of rotation of the middle drum 25 means the rotation axis of the rotating middle drum 25, and the distances R1 and R2 are from the uppermost end C1 of the middle drum 25 and the lowermost end C2 of the fixed drum 21, respectively. It represents the shortest distance to the axis of rotation.

In the portion where the intermediate drum 25 and the fixed drum 21 face each other, the positional relationship between the uppermost end C1 and the lowermost end C2 is such that the distance R2 is shorter than the distance R1 at least near the center of the winding angle θ. Attach both drums. With such a positional relationship, an appropriate air film is formed between the tape 27 and the fixed drum 21 or the fixed drum 22 as shown in FIG. 1, regardless of the traveling direction of the tape 27 such as normal reproduction and reverse reproduction. It This can reduce the running load of the tape 27 on the drum unit 20.

As a method of determining the relative position between the uppermost end C1 and the lowermost end C2, for example, as shown in FIG. 2A, the diameter of the fixed drum 21 at the lowermost end C2 and the uppermost end of the middle drum 25 are determined. The diameter of C1 is made equal, and the fixed drum 2
It can be easily realized by slightly deviating the central axis of 1 and the rotation axis of the middle drum 25. Specifically, the center axis of the fixed drum 21 may be displaced by about 10 μm with respect to the center axis of the middle drum 25 in a direction opposite to the winding portion around the tape 27 (direction of arrow Y1 in FIG. 2A). .

Further, as shown in FIGS. 1 and 2 (b), the diameter of the lowermost end C2 of the fixed drum 21 is made smaller than the diameter of the uppermost end C1 of the middle drum 25, and the center axis of the fixed drum 21 and It can also be easily realized by aligning the rotation axis of the drum 25. Specifically, the diameter of the lowermost end C2 of the fixed drum 21 is made smaller than the diameter of the uppermost end C1 of the middle drum 25 by about 10 μm. In addition, this drum unit 2
It goes without saying that the configuration method of 0 is not limited to the above combination. Whichever method is adopted, the tape 27 is more likely to contact the outer peripheral surface of the intermediate drum 25 than the fixed drum in the vicinity of the winding angle θ.

Next, a rotary head drum device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3A is a front view of the drum unit 30 of the second embodiment. The drum unit 30 is the first fixed drum 3 as in the first embodiment.
1, a middle drum 35 and a second fixed drum 32. The taper portion 36 formed on the fixed drum 31 is configured such that at least the surface roughness of the tape running surface becomes gradually rougher as it moves away from the uppermost end C1 of the outer peripheral surface of the middle drum 35 as shown in FIG. 3B. It is a thing. As a method of realizing such surface roughness, there is a method of changing the cutting depth of a cutting tool (for example, the cutting tool tip shape R), and it is possible to easily perform a taper processing.

In this way, the tape 27 running along the leads of the fixed drum 32 has a large frictional resistance in the portion of the fixed drum 31 where the surface roughness is rough, and the air film in the portion where the surface roughness is fine is larger than that in the rough portion. The frictional resistance becomes smaller due to the effect of. For this reason, in the portion where the tape 27 is in contact with the fixed drum 31, a force that pushes down the tape 27 is generated, so that the tape 27 travels along the lead of the fixed drum 32 without difficulty, and the straight line of the track pattern. Sex can be easily improved.

Next, a rotary head drum device according to a third embodiment of the present invention will be described with reference to FIG. Figure 4
(A) is a front view of the drum unit 40 of 3rd Example. The drum unit 40 includes a first fixed drum 41, a middle drum 45, and a second fixed drum 42 as in the first embodiment.
It is composed of As shown in FIG. 4A, the taper portion 46 formed on the fixed drum 41 is formed by forming a line-shaped processing mark on the tape running surface of the fixed drum 41 so as to be parallel to the tape running direction. At least in the region of the fixed drum 41 where the tape 27 travels, the surface roughness increases as the distance from the intermediate drum 45 increases. Such surface roughness can be easily processed by the same method as the method of processing the lead of the fixed drum 42.

According to this structure, the fixed drum 42
The tape 27 running along the lead of the fixed drum 4
The frictional resistance is large in the rough surface portion 1 and the frictional resistance is smaller in the fine surface roughness portion due to the influence of the air film than in the rough portion. At the portion where the tape 27 is in contact with the fixed drum 41, a force that pushes down the tape 27 is generated. Therefore, the tape 27 travels along the leads of the fixed drum 42 without difficulty, and the linearity of the track pattern can be easily improved. As shown in FIGS. 3 and 4, the surface roughness of the first fixed drum does not have to be successively roughened as described above, but may be roughened in stages.

Further, a rotary head drum device according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a front view of the drum unit 50 of the fourth embodiment. The drum unit 50 is composed of a first fixed drum 51, a middle drum 55, and a second fixed drum 52, as in the first embodiment. The taper portion 56 of the fixed drum 51 has a surface roughness at least equal to the surface roughness of the fixed drum 52,
Or it is made coarse.

According to this structure, since the surface roughness of the fixed drum 51 is equal to or rougher than the surface roughness of the fixed drum 52, the sliding resistance of the fixed drum 51 with respect to the tape 27 is larger than the sliding resistance of the fixed drum 52. Become. That is, a force that pushes down the tape 27 is generated over the entire length of the tape 27 wound around the drum unit 50. Therefore, since the tape 27 naturally follows the lead, it is easy to secure the linearity of the track pattern,
It is possible to significantly reduce the adjustment man-hours.

Further, the sliding characteristic of the tape 27 depends on the roughness of the drum material, and the sliding resistance is reduced by making the surface roughness of the drum material fine. In particular, when it is 1 μm or less, the sliding resistance is greatly reduced. However, 0.1 μ
If the thickness is less than m, the probability that the sticking phenomenon of the tape 27 will occur in a high humidity environment will be undesirably 0.1 μm or less. Therefore, the surface roughness of the fixed drum 51 is 0.1
By setting the thickness in the range of μm to 1 μm, it is possible to minimize the increase in the running load of the tape 27 in the drum unit 50.

[0031]

As described above, according to the invention described in claim 1 of the present application, the relative positional relationship (outer diameter of the outer peripheral portion) between the first fixed drum and the middle drum which configure the drum unit is defined. Therefore, an appropriate air film can be formed between the tape and the first fixed drum or the second fixed drum regardless of the traveling direction of the tape such as normal reproduction and reverse reproduction. In this way, it is possible to minimize the increase in the tape running load in the drum unit.

According to the second and third aspects of the present invention, the tape which runs along the leads of the second fixed drum has a rough surface portion of the first fixed drum. The frictional resistance is large, and the frictional resistance becomes smaller in a portion with a small surface roughness due to the influence of the air film than in a rough portion. As a result, a force that pushes down the tape is generated at the portion where the tape is in contact with the first fixed drum, so the tape travels along the lead of the second fixed drum without difficulty, and the tape moves straight along the track pattern. Sex can be easily improved.

Further, according to the inventions of claims 4 and 5, the surface roughness of the first fixed drum is equal to or more than the surface roughness of the second fixed drum, and therefore the first fixed drum is wound around the drum unit. A force that pushes down the entire length of the tape is generated, and the tape naturally follows the lead. Therefore, it is easy to ensure the linearity of the track pattern, and it is possible to significantly reduce the adjustment man-hours. Further, since the surface roughness of the second fixed drum is regulated, it is possible to suppress an increase in running load in the drum unit.

[Brief description of drawings]

FIG. 1 is a side view of a drum unit in a rotary head drum device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing relative positions of the drums in the drum unit of the first embodiment.

FIG. 3A is a front view of a drum unit in a rotary head drum device according to a second embodiment of the present invention, and FIG.
FIG. 4 is an explanatory diagram of surface roughness of a taper portion provided on a fixed drum.

FIG. 4A is a front view of a drum unit in a rotary head drum device according to a third embodiment of the present invention, and FIG.
FIG. 4 is an explanatory diagram of surface roughness of a taper portion provided on a fixed drum.

FIG. 5 is a front view of a conventional drum unit in a rotary head drum device according to a fourth embodiment of the present invention.

FIG. 6 is a front view showing a configuration example of a conventional drum unit.

[Explanation of symbols]

 20, 30, 40, 50 Drum unit 21, 31, 41, 51 First fixed drum 22, 32, 42, 52 Second fixed drum 23 Lead 24 Magnetic head 25, 35, 45, 55 Medium drum 26, 36, 46,56 Tapered part 27 Tape C1 Top end C2 Bottom end θ Tape wrap angle

Claims (5)

[Claims] 1. A first fixed drum, a second fixed drum formed with a lead for guiding the running of a tape, and coaxially attached to the first fixed drum; the first fixed drum; A middle drum having a magnetic head, which is rotatably mounted between the second fixed drums;
A rotary head drum device comprising: the first fixed drum, wherein the first fixed drum has an axial direction with respect to the middle drum in at least a region where the tape of the first fixed drum contacts and travels. A taper portion whose outer diameter increases as the distance increases, and the first fixed drum and the middle drum have a center of rotation of the middle drum at least at the center of the winding angle of the tape. To the uppermost end of the outer peripheral surface of the middle drum, the distance R1 is greater than the distance R2 from the center of rotation of the middle drum to the lowermost end of the first fixed drum. Rotating head drum device. 2. The rotary head drum device according to claim 1, wherein the surface roughness of the first fixed drum is gradually roughened from the lower end side to the upper end side at least on the tape running surface. 3. The first fixed drum forms a processing mark of a stripe on the tape running surface so as to be parallel to the tape running direction, and in a region where the tape contacts and runs, a distance from the middle drum is 2. The rotary head drum device according to claim 1, wherein the surface roughness is increased with increasing distance. 4. The surface roughness of the tape running surface of the first fixed drum is at least equal to or rougher than the surface roughness of the second fixed drum.
The rotary head drum device described. 5. The rotary head drum device according to claim 4, wherein the second fixed drum has a surface roughness of a tape running surface in a range of 0.1 μm to 1 μm.