JPS60173753A - Fixed guide member of magnetic tape and its production - Google Patents

Abstract

PURPOSE:To extend the contacting area between a fixed guide member and a magnetic tape to reduce a coefficient of friction even if a high-density magnetic tape such as a metal tape, a metal-deposited magnetic tape, or the like is used, by forming smoothly tops of sectional curves of the fixed guide member. CONSTITUTION:Tops of sectional curves of a fixed guide drum 3' (rugged curves appearing in the cut when the surface of the fixed guide drum is cut orthogonally to its mean plane) are rounded to be formed smoothly, and minute undulations 25 are given to them, thus finishing the fixed guide drum 3' to <=2mum surface roughness, desirably, 0.5-0.6mum minute surface roughness. Then, the contacting area between the fixed guide drum 3' and a high-density magnetic tape Ta is wide. Consequently, the contacting pressure between the fixed guide drum 3' and the magnetic tape Ta is reduced even if metals are brought into contact with each other between the fixed guide drum 3' and the magnetic tape Ta.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to magnetic recording and reproducing devices, particularly VTR devices that record and reproduce high frequency signals such as video signals at high density. The present invention relates to a fixed guide member that contacts the magnetic surface of a high-density magnetic tape and guides the running of the magnetic tape, and a method for manufacturing the fixed guide member.

Specifically, the above-mentioned fixed guide member refers to a fixed guide drum, a fixed guide bin, a fixed guide plate, etc. of a helical scan type rotary head assembly of a magnetic recording/reproducing device.

[Background of the invention]

In such magnetic recording and reproducing apparatuses, a coated magnetic tape based on cobalt iron oxide has conventionally been used as a recording medium. However, today, in order to downsize magnetic recording and reproducing devices and improve image quality, there is a demand for the use of high-density magnetic tapes such as metal tapes and metal-deposited magnetic tapes. This metal tape has a high coercive force, and the metal-deposited magnetic tape has a large residual magnetic flux density, and furthermore, the magnetic layer thickness can be reduced to several thousand to less than 〇, thereby reducing thickness loss. On the other hand, since metal tape uses fine metal powder magnetic material that is not oxidized, it is easily susceptible to oxidation and corrosion when used outdoors under various conditions, such as in a VTR, and rust may occur locally. metal may be exposed. In addition, with metal vapor-deposited magnetic tape, a coating layer can be provided on the magnetic metal to provide a lubricating effect, but in order to minimize thickness loss, the magnetic metal is basically left exposed. The actual situation is to use it.

Next, a conventional fixed guide member, a fixed guide drum of a helical scan type rotary head assembly of a VTR, will be explained with reference to FIGS. 1 to 4.

The magnetic tape guide drum of the helical scan type rotary head assembly of such a VTR is composed of a pair of magnetic tape guide drums 2.3 having the same outer diameter and arranged coaxially and close to each other at a predetermined interval 4 above and below. The upper guide drum 2 is a rotary guide drum rotating in the direction of arrow a, and the lower guide drum 6 is a fixed guide drum. The guide drum 2.6 is made of aluminum alloy, for example. Two rotary magnetic heads H are provided in the gap between the pair of guide drums 2 and 6 at an angular interval of 180 degrees, and are configured to rotate together with the rotary guide drum 2. The magnetic tape Ta runs diagonally in the b direction with respect to the magnetic tape guide drum 1. In the figure, 5 is a rotating shaft, 6 is a bearing,
7 is a support, and 8 is a pulley on which a belt from a drive source is stretched. When the magnetic tape guide drum 1 is driven, as shown in FIG. By,
Force C is working from the bottom to the top.

Further, the fixed guide drum 6 also contacts the magnetic tape Ta over an area equivalent to that of the rotating guide drum 2, and a frictional force d is exerted thereon. As a result, as can be seen from the cross-sectional view showing the displacement state of the magnetic tape Ta in FIG. 2, the magnetic tape Ta is almost floating on the rotating guide drum 2, but the magnetic tape Ta is almost not in contact with the fixed guide drum 3. ing. In addition, the symbol 6 in the figure
0 is the opening.

The surface of the above-mentioned conventional fixed guide drum 6, that is, the surface that contacts the magnetic surface of the magnetic tape Ta, is cut to form a third
As shown in the figure, sharp cutting tool marks T and M with a surface roughness of about 4 ridges are left, and the fixed guide drum 6 and magnetic tape Ta come into close contact with the water film during high temperature and high humidity. It is designed to prevent

Here, when using a conventional coated magnetic tape based on cobalt iron oxide as the magnetic tape Ta, the coated magnetic layer of this coated magnetic tape based on cobalt iron oxide is composed of an organic material containing magnetic powder. Therefore, due to the protective film action of the organic material on the coated magnetic layer, even if the coated magnetic layer is repeatedly deformed during sliding with the sharp cutting tool marks T and M of the fixed guide drum O, it will not be deformed. It can be easily followed and there is no risk of damaging the coated magnetic layer. In addition, due to the lubricating effect of the organic substance in the coated magnetic layer described above, even if the contact area between the coated magnetic layer and the fixed guide drum 3 is small, the frictional resistance between the coated magnetic layer and the fixed guide drum 3 does not increase. No problems arise.

However, when using high-density magnetic tape such as metal tape or metal-deposited magnetic tape in place of the above-mentioned cobalt iron oxide coated magnetic tape in order to downsize magnetic recording and reproducing devices and improve image quality, the following The problem arises. That is, in the case of a metal tape, multi-metals are exposed due to the occurrence of rust, and in the case of a metal-deposited magnetic tape, magnetic metals are exposed. For this reason, as shown in FIG. 4, the high-density magnetic tape Ta such as metal tape or metal-deposited magnetic tape and the sharp cutting tool marks T and M on the fixed guide drum 3 come into metal-to-metal contact. Moreover, the contact area between the high-density magnetic tape Ta and the fixed guide drum 3 is small.

Therefore, the contact pressure between the high-density magnetic tape Ta and the fixed guide drum 3 becomes the highest. That is, since the vertical load applied to the magnetic tape Ta is constant, if the contact area between the magnetic tape T'a and the fixed guide drum 6 is small, the magnetic tape T
The contact pressure between a and the fixed guide drum 3 becomes a dog. As a result, the stick-slip phenomenon and the running magnetic tape Ta
This results in slight vibrations, etc., leading to an increase in wow and flutter and jitter components. Furthermore, in the case of a high-density magnetic tape in which the metal is exposed, the sharp tool marks T and M deform the magnetic layer severely and repeatedly, resulting in damage to the magnetic layer.

In the above, the fixed guide drum 6 of the helical scan type rotary head assembly of a VTR has been explained. Similar problems arise with components.

[Purpose of the invention]

The present invention aims to provide a fixed guide member for a magnetic tape that solves the above-mentioned problems, and a method for manufacturing the fixed guide member.

[Summary of the invention]

The present invention is characterized in that the peak of the cross-sectional curve of the fixed guide member is formed smoothly to increase the contact area between the high-density magnetic tape and the fixed guide member.

Furthermore, the present invention involves cutting the contact surface of the unprocessed fixed guide member with the magnetic tape, and then lapping the cut surface to increase the contact area between the high-density magnetic tape and the fixed guide member. It is characterized by being made to do.

[Embodiments of the invention]

Hereinafter, an embodiment of the magnetic tape fixed guide member of the present invention and an embodiment of the method of manufacturing the magnetic tape fixed guide member of the present invention will be described with reference to FIGS. 5 to 10.

First, an embodiment of the magnetic tape fixed guide member of the present invention will be described with respect to a fixed guide drum of a helical scan type rotary head assembly of a VTR.

As shown in FIG. 5, the cross-sectional curve (
That is, when the surface of the fixed guide drum 3' is cut at right angles to its average plane, it refers to the uneven curve that appears on the cut. ) is formed into a smooth, rounded peak with minute ridges,! 1l125 is applied to form one surface of the fixed guide drum 3' to a fine surface roughness of 2 μm or less, preferably 05 to 0.6 M.

In this way, the fixed guide drum 6' of the present invention has a smooth crest of its cross-sectional curve, so as shown in FIG.
Fixed guide drum 6' of the present invention and high density magnetic tape Ta
The contact area between the fixed guide drum B and the high-density magnetic tape Ta is smaller than that between the conventional fixed guide drum B and the high-density magnetic tape Ta as shown in FIG. Therefore, even if the fixed guide drum 6' and the high-density magnetic tape Ta come into metal-to-metal contact, the contact pressure between the fixed guide drum 6' and the magnetic tape Ta can be reduced. As a result, it is possible to prevent stick-slip phenomena and slight vibrations of the magnetic tape Ta while it is running.
Moreover, wow and flutter and jitter components can be reduced. In addition, since the peak of the cross-sectional curve of the fixed guide drum 6' is formed smoothly, even if the magnetic surface of the high-density magnetic tape Ta is repeatedly deformed by the fixed guide drum 3' of the present invention, the magnetic tape TIL remains stable. There is no risk of damage to the surface. In addition, I gave him 25 yen, so
It is possible to prevent the fixed guide drum 3' and the magnetic tape Ta from coming into close contact with each other due to the water film during high temperature and high humidity, and it is possible to make it less susceptible to the influence of humidity.

Verification of the effects of the fixed guide drum 6' of the present invention described above will be explained below.

Figure 7 shows a fixed guide drum and high-density magnetism.

1 is a schematic diagram showing an apparatus for measuring the coefficient of friction between a magnetic surface and a magnetic surface. In this friction coefficient measuring device, a rotating guide drum 2 is connected to a motor (not shown), and a high-density magnetic tape Ta (for example, a metal tape) is wound around a fixed guide drum 6' at a wrapping angle of 90°. A load of 1 is applied to one end of this magnetic tape Ta.
Hang 6. On the other hand, a load cell 10 is connected to the other end of the magnetic tape Ta, and an automatic recorder 1 is connected to the load cell 10.
Connect 1. The preload cell 10 is equipped with a mechanism 12 for reciprocating the load cell, and is configured so that the f angle detected by the load cell 10 is automatically recorded in the automatic recorder 11.

In the above friction coefficient measuring device, the rotating guide tom 2
by rotating it in the direction of the arrow to connect the fixed guide drum 3' and the load 16.
The tension T between , and the tension T2 between the fixed guide drum 6' and the load cell 11 are measured, respectively, and the friction coefficient μ can be calculated using the following formula.

FIG. 8 is a graph in which the horizontal axis represents the surface roughness of the fixed guide drum 3' and the vertical axis represents the coefficient of friction between the fixed guide drum 6' and the magnetic surface of the magnetic tape Ta. This graph shows the fixed guide drum 6' produced as described above by lapping the cut surface of the fixed guide drum 6' in contact with the magnetic tape Ta to change its surface roughness. This experiment was conducted under the following conditions to observe changes in the coefficient of friction with the magnetic surface of the magnetic tape T&. The temperature and humidity are 25°C, 50% RH, the magnetic tape Ta used is a metal tape, and the diameter of the fixed guide drum 3' is 62 mm.
The material is aluminum (AH8), and the winding angle of the magnetic tape T& with respect to the fixed guide drum 6' is 90°. As is clear from this graph, by reducing the surface roughness of the fixed guide drum 3', that is, by making the peak of the cross-sectional curve of the fixed guide drum B smooth, the fixed guide drum 6' and the magnetic tape T& It can be seen that the friction coefficient decreases.

FIG. 9 is a graph in which the surface roughness of the fixed guide drum 3' is plotted on the horizontal axis and the image jitter is plotted on the vertical axis.

This graph shows that high-density magnetic tape such as metal tape or metal-deposited magnetic tape can be produced by lapping the cut surface of the fixed guide drum 3' in contact with the magnetic tape Ta to change its surface roughness. This is to see how the video jitter due to the tape Ta changes.

The amount of jitter can be determined from the detection ability of the human eye, and as shown in this graph, it is thought to be less than 0.15μ. The surface roughness of the fixed guide drum 6' that satisfies this condition may be 21 #rL or less. Further, the optimum thickness is preferably 0.5 to 0.6 μm in consideration of processability during mass production. As is clear from this graph, it can be seen that image jitter can be reduced by making the surface roughness of the fixed guide drum 6' smooth.

Similar to the graph in FIG. 8, FIG. 10 shows the surface roughness of the fixed guide drum 5' on the horizontal axis and the fixed guide drum 31 on the vertical axis.
It is a graph showing the coefficient of friction between the magnetic tape Ta and the magnetic surface of the magnetic tape Ta. This graph shows changes in surface roughness and friction coefficient at high temperatures of 40°C and 80% RI.As is clear from this graph, the peak of the cross-sectional curve of the fixed guide drum 3' By forming it smoothly and forming minute undulations 25, it is possible to prevent the fixed guide drum 6' and the magnetic tape Ta from coming into close contact with each other in high humidity, and is less susceptible to the influence of humidity and has a low coefficient of friction. It can be seen that it has the effect of not increasing the

In the above-described embodiment, the peak of the cross-sectional curve of the identification guide drum 3' is rounded and formed smoothly, but it may be flattened and formed smoothly. In short, it is sufficient to increase the contact surface between the fixed guide drum 3' and the magnetic tape Ta.

Furthermore, in the above embodiment, the surface roughness of the fixed guide drum 3' was set to 21 krIL or less, but if the peak of the cross-sectional curve of the fixed guide drum 6' was smooth, the above-mentioned surface roughness would be 2 years or more. It's okay.

Further, in the above-described embodiment, the fixed guide drum 6' of the helical scan type rotary head assembly of the VTR is
Although the present invention has been described above, it can also be applied to fixed guide bins, fixed guide plates, etc. of other magnetic recording and reproducing devices.

Next, an embodiment of the method for manufacturing a fixed guide member for a magnetic tape according to the present invention will be described with reference to a method for manufacturing a fixed guide drum for a helical scan type rotary head assembly of a VTR.

First, the contact surface of the unprocessed fixed guide drum 6' with the magnetic tape Ta is cut. At this time, the fixed guide drum 6
As shown in FIG. 5, the cross-sectional curve of '' remains sharp T and M.

Next, the cut surface of the fixed guide drum 6' is lapped so that the top of the cross-sectional curve of the fixed guide drum 6' is rounded and smooth, and minute undulations 25 are formed, as shown in FIG.
The fixed guide drum 6' is given a surface roughness of 2 μm or less, preferably a fine surface roughness of 0.5 to 0.6 μm.

As described above, in the method of manufacturing a fixed guide drum of the present invention, first the contact surface of the fixed guide drum 6' with the magnetic tape Ta is cut, and then the cut surface is lapped, so that it is different from that of the conventional fixed guide drum. It is possible to use the fixed guide drum 6 manufactured by the manufacturing method, that is, the fixed guide drum 6 whose contact surface with the magnetic tape Ta is machined. Therefore, the above-described fixed guide drum 6' of the present invention can be manufactured easily and inexpensively by simply adding lapping equipment to conventional cutting equipment.

In the above embodiment, the method for manufacturing the fixed guide drum 6' of a helical scan type rotary head assembly of a VTR has been described, but the method for manufacturing fixed guide pins, fixed guide plates, etc. of other magnetic recording and reproducing devices is also applicable. It can also be applied to

Further, in the above embodiment, the surface roughness of the fixed guide drum 6' was made 2 μm or less by lapping, but if the peak of the cross-sectional curve of the fixed guide drum 6' is smooth, the above-mentioned surface roughness can be reduced to 2 μm or less. It may be #n or more.

〔Effect of the invention〕

As is clear from the above embodiments, the magnetic tape fixed guide member of the present invention has a smooth peak of its cross-sectional curve, so high-density magnetic tape such as metal tape or metal-deposited magnetic tape is used. Even if the fixed guide member and the magnetic tape are in contact with each other, the contact area between the fixed guide member and the magnetic tape can be increased, and the coefficient of friction between the fixed guide member and the magnetic tape can be reduced.

As a result, stick-slip phenomena and slight vibrations of the magnetic tape during running can be prevented, and wow and flutter and jitter components can be reduced. Furthermore, damage to the magnetic surface of the magnetic tape can be prevented.

Further, the method for manufacturing a fixed guide member for a magnetic tape of the present invention includes cutting the contact surface of the fixed guide member with the magnetic tape,
Then, the cut surface is lapped to manufacture the fixed guide member. Therefore, the fixed guide member of the present invention can be easily and inexpensively manufactured by simply adding the lapping equipment to the conventional cutting equipment. I can do it.

[Brief explanation of the drawing]

Figure i1 is a schematic diagram of a helical scan type rotary head assembly of a VTR, Figure 2 is a sectional view taken along line I[-II in Figure 1, and Figure 6 is a diagram showing sharp tool marks on a conventional fixed guide drum. , FIG. 4 is a diagram showing the state of contact between a conventional fixed guide drum and a high-density magnetic tape. 5 to 10 show an embodiment of the fixed guide member of the magnetic tape of the present invention, FIG. 5 is a diagram showing a cross-sectional curve of the fixed guide drum, and FIG. 6 is a diagram showing the fixed guide drum and the high-density magnetic Figure 7 shows the state of contact with the tape. Figure 7 is a schematic diagram of a device for measuring the coefficient of friction between the fixed guide drum and the magnetic surface of the magnetic tape. Figure 8 shows the surface roughness of the fixed guide drum at normal temperature and humidity. A graph showing the relationship between the coefficient of friction between the fixed guide drum and the magnetic surface of the magnetic tape. Figure 9 is a graph showing the relationship between the surface roughness of the fixed guide drum and image jitter. Figure 10 is a graph showing the relationship between the surface roughness of the fixed guide drum and the image jitter. Figure 10 is a graph showing the relationship between the fixed guide drum and the magnetic surface of the magnetic tape. 3 is a graph showing the relationship between the surface roughness of the fixed guide drum and the coefficient of friction between the fixed guide drum and the magnetic surface of the magnetic tape. 1... Magnetic tape guide drum, 6'... Fixed guide drum, 25... Minute ridges, 1'a... High density magnetic tape. Agent Patent Attorney Tadashi Akimoto 11 Figure 2 Figure 3 Cause Figure 4 Figure 5 Figure 6
, )2 G 8

Claims (1)

[Claims] 1. In a fixed guide member that comes into contact with the magnetic surface of a high-density magnetic tape such as a metal tape or a metal-deposited magnetic tape to guide the running of the magnetic tape, the cross-sectional curve of the fixed guide member is A magnetic tape fixed guide member characterized by having a smooth peak. 2. The fixed guide member for a magnetic tape according to claim 1, characterized in that the surface roughness is 2 μm or less. 3. In a method for manufacturing a fixed guide member that contacts the magnetic surface of a high-density magnetic tape such as a metal tape or a metal-deposited magnetic tape to guide the running of the magnetic tape, the contact surface of the unprocessed fixed guide member with the magnetic tape 1. A method for producing a fixed guide member for a magnetic tape, comprising cutting the magnetic tape, and then lapping the cut surface. 4. A method for producing a fixed guide member for a magnetic tape, which is characterized in that it is lapped to have a surface roughness of 2 μm or less after cutting.