JPS6258059B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fixed reel type endless tape running device used in fixed head type VTRs, etc.
In particular, the present invention relates to an endless tape running device that can reduce wear on the coated surface of the tape.

Image signal recording and reproducing devices (VTR), especially fixed head type VTRs that run an endless magnetic tape at a high speed of several meters per second or more, and record and play back with a fixed magnetic head along the length of the tape.
In order to reduce the size of the device and prevent wear and tear on the tape, an endless tape running device in which a reel for winding the tape is fixed has been devised.

FIG. 1 shows an example of this fixed reel type endless tape running device, in particular an example in which the tape drive mechanism is arranged inside the reel. 1st
In the figure, an endless magnetic tape 1 is wound on the outer peripheral surface of an annular body 2 serving as a fixed reel, and the lower surface of the wound portion 1' is supported by three supports 4, for example. The annular body 2 has a communication part 3 that communicates both the inner and outer peripheral surfaces, and the tape 1 pulled out from the innermost circumference of the tape winding part 1' through the communication part 3 is guided inward by a guide 5. After slidingly contacting a head guide 8 and a magnetic head 9 attached thereto between a pair of vertical regulation guides 6 and 7, the tape is guided between a capstan 10 and a pinch roller 11 constituting a tape drive mechanism.
The tape 1 that has come out between the capstan 10 and the pinch roller 11 forms a slack 12 by wrapping around a part of the capstan 10, and then jumps over the annular body 2 and the tape winding part 1' and passes through the guide 13. The tape is guided by and wound around the outermost circumference of the tape winding section 1'.

Generally, in an endless tape winding section on a reel, there is a relative speed, that is, slippage, between adjacent tapes, and this relative speed ΔV is calculated as ΔV when considering the i, i+1th tape interval from the innermost circumference of the winding section. =V・t/(R+i・t)...(1). Here, V: Tape running speed t: Tape thickness R: Reel radius In order to record and reproduce image signals with a fixed head, the tape running speed must be several meters per second or more. In this case, smooth sliding between the tapes is essential from the viewpoint of running stability. For example, the tape running speed is 5 m/
sec, reel radius 50mm, tape thickness 24μm
In this case, the relative velocity V is approximately 0.25 cm/sec, and low friction is required at such a low relative velocity.

For this purpose, the surface of the tape opposite to the magnetic surface has traditionally been coated with graphite, etc.
This reduces the coefficient of friction between the tapes at low relative speeds. However, such a coated surface generally has a relatively large surface roughness (center line average roughness R = 2
~3 μm), it has a tendency to wear very easily, and the coefficient of friction increases on the worn graphite coating surface, so as the wear increases, running stability becomes insufficient.

By the way, as shown in FIG. 2, an air film is generated between the tape 21 traveling at high speed and the guide 22 having a cylindrical surface, and the thickness h of the air film is given by the following equation.

h=K・R {6μV/(T−σV ² )} ^2/3 …(2) where K: Constant (≒0.3) R: Cylindrical guide radius μ: Air viscosity coefficient V: Tape running speed T: Tape tension σ: Tape surface density For example, when T = 50 g, V = 5 m/sec, and R = 20 mm, h will be 3 to 4 μm, but this value is obtained assuming that the tape and guide surface are sufficiently smooth, and in reality, the graph Since the surface roughness of the graphite-coated surface is 2 to 3 μm, if the surface of the tape 21 on the guide 22 side is the graphite-coated surface, it is difficult to form an air film.

By the way, in the endless tape running device shown in FIG. 1, as is clear from the fact that the magnetic surface of the tape 1 comes into contact with the head guide 8 and the magnetic head 9, the outer peripheral surface of the annular body 2 and the guides 6 and 7 contact with each other. is in contact with the graphite coating surface. Therefore, even when tape 1 is running at high speed, tape 1
It is difficult to form an air film between the outer circumferential surface of the annular body 2 and the guides 6 and 7, and therefore the graphite coating surface is easily worn, causing graphite powder to fall off and the friction coefficient of the tape to increase.
The disadvantage is that stable high-speed running of the tape cannot be expected.

The present invention has been made in view of the above points, and
The purpose is to provide an endless tape running device that reduces wear on the coated surface of the tape, thereby increasing the lifespan of the tape and allowing stable high-speed running over a long period of time.

That is, in the present invention, the surface roughness of the magnetic surface of the tape is approximately 0.1 to 0.2 μm in center line average roughness, which is extremely small compared to the coated surface of graphite, etc., and is a condition in which air film is likely to occur. Taking advantage of this fact, the tape is wound around the outer peripheral surface of the annular body, which is a fixed reel, with the magnetic surface facing inside.

The present invention will be specifically explained below using examples.
FIG. 3 is a plan view of an endless tape traveling device showing one embodiment of the present invention, and is an example in which the tape drive mechanism is arranged inside the reel, similar to FIG. 1.

In FIG. 3, reference numeral 21 denotes an endless magnetic tape, which is wound on the outer peripheral surface of an annular body 22 serving as a fixed reel with the magnetic surface on the inside and the coated surface made of graphite or the like on the outside. The lower surface of ' is supported by three support rollers 24, for example. The tape 21 pulled out from the innermost periphery of the tape winding part 21' through a communication part 23 formed in the annular body 22 so as to communicate both the inner and outer peripheries is guided inward by a guide 25, and is further guided by a pair of upper and lower parts. After sliding between the regulation guides 26 and 27 on the head guide 28 provided on the same side as these guides 26 and 27 and the magnetic head 29 attached thereto, the capstan 30 and the pinch that constitute the tape drive mechanism are removed. roller 3
1, the tape winding part 2 of the tape 21
The annular body 22 is driven to run at a speed at which an air film is formed between the innermost circumference of the annular body 1' and the outermost circumference of the annular body 22.
The pinch roller 31 is attached to a pinch holder 34 whose one end is pivoted, and is pressed against the capstan 30 by a spring 35.

The tape 21 that has come out between the capstan 30 and the pinch roller 31 is regulated by the plate-shaped guide 36 and forms a slack 32 in the form of wrapping around a part of the capstan 30. The tape jumps over the tape winding section 21', is guided by the guide 33, and is wound around the outermost circumference of the tape winding section 21'.

For tape slack 32, refer to guide 3.
By changing the shape and position of 6 and 33, it is also possible to form a slack so as to wrap around a part of the pinch roller 31. Further, the guide 33 can be set so that the tape 21 comes out from between the capstan 30 and the pinch roller 31 and passes under the annular body 22 and the tape winding portion 21' after forming the slack 32.

In the endless tape running device configured as described above, the tape 21 is wound around the outer peripheral surface of the annular body 22 with the magnetic surface, which has very small surface roughness, inside. Several meters
When traveling at the above high speed, an air film is effectively formed between this magnetic surface and the outer peripheral surface of the annular body 22. Also guides 25, 26, 27, 2
8, since the magnetic surfaces of the tapes 21 are in contact with each other, an air film is likely to be formed between them.

Therefore, there is almost no wear on the graphite coated surface of the tape 21, and the graphite powder is prevented from falling off and the resulting increase in the coefficient of friction between the tapes at the tape winding portion 21' is prevented, so that the tape 21 can last for a long time. Stable high-speed running can be achieved, and the tape can also have a long service life.

Furthermore, what the air film can do effectively is that the tension when pulling out the tape 21 through the communication part 23 of the annular body 22 is reduced, and the guide 25,
The tape tension at 26, 27, and 28 is also reduced, leading to the effect that the torque of the drive motor for the capstan 30 can be reduced.

FIG. 4 shows another embodiment of the present invention, in which the tape drive mechanism is disposed outside the reel.
To briefly describe the same parts with the same reference numerals as in FIG. 2, the tape 21 is wound around the annular body 22 and pulled out from the tape winding part 21' through the communication part.
is guided inward by the guide 25, and furthermore, a guide 37 stands obliquely inside the annular body 22,
38 to the annular body 22 and the tape winding section 2
1', the capstan 3 is guided by the guide 39 and the vertical regulation guide 40 to run at a position higher than the upper surface of the tape winding part 21'.
0 and the entrance side pinch roller 31a. Capstan 30 and entrance side pinch roller 31
The tape 21 that has come out between the capstan 30 and
While being guided between the output side pinch roller 31b and the output side pinch roller 31b, it is guided by the head guide 28 and comes into sliding contact with the magnetic head 29. The tape 21 exits between the capstan 30 and the exit side pinch roller 31b.
After forming the slack 32 on the slack receiving table 41 and in contact with the guide wall 42, the guide 4
3 and 44 to the same position as the upper surface of the tape winding section 21', and is wound around the outermost circumference of the tape winding section 21'.

In the above embodiment as well, by winding the tape 21 on the outer peripheral surface of the annular body 22 with the magnetic surface facing inside, substantially the same effect as in the embodiment shown in FIG. 3 can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of an endless tape running device using a conventional fixed reel type, Fig. 2 is a drawing showing how an air film is generated between a tape running at high speed and a cylindrical guide, and Fig. 3 is a plan view showing an example of an endless tape running device using a conventional fixed reel type. A fourth plan view of an endless tape running device in which a tape drive unit is arranged inside a reel, which is an embodiment of the present invention.
The figure is a plan view of another embodiment of the present invention, an endless tape running device in which a tape drive section is arranged outside the reel. 21... Endless magnetic tape, 21'... Tape winding portion, 22... Annular body, 23... Communication portion,
29...Magnetic head, 30...Capstan, 3
1, 31a, 31b...Pinch roller.

Claims (1)

[Claims] 1. An endless magnetic tape having a communication part that communicates both the inner and outer circumferences, and having a magnetic surface and a coating surface on both sides on the outer circumference is wound, and this tape is pulled out from the innermost circumference of the winding part through the communication part. A fixedly installed annular body, a guide mechanism that guides the endless magnetic tape pulled out from the communication part so that it is wound around the outermost circumference of the winding part, and a capstan and a pinch arranged inside or outside of the annular body. An endless tape running device comprising a tape drive mechanism comprising a roller and driving the endless magnetic tape to run at a speed such that an air film is formed between the innermost circumference of the winding part of the endless magnetic tape and the outer circumferential surface of the annular body, The endless tape running device is characterized in that the endless magnetic tape is wound on the outer peripheral surface of the annular body with the magnetic surface having a smaller surface roughness than the coated surface facing inside.