JPH0877663A - Rotating drum device - Google Patents

Abstract

(57) [Summary] [Purpose] To control the outer diameter and taper of the rotating drum.
It can be done easily, and the head can be attached and adjusted.
Be able to do it accurately. [Structure] A rotary drum 3 equipped with a magnetic head 2 and a magnet
Has a lead 6 that regulates and guides the air tape 1 at a predetermined incident angle.
And a fixed drum 5 for
The outer peripheral surface of the ram 3 has the first and second tapered portions 31 and 3
2 and the straight portion 33 between them,
Diameter d of the lower end of the ram 3₁Is the diameter d of the fixed drum 5.₀Than
Is also small, the upper end diameter d of the rotating drum 3₃Fixed drum
Diameter 5 ₀Greater than. Outer diameter d of the straight portion 33
₂Can be easily and accurately measured at a fixed position,
The taper angle θ of the taper portions 31 and 32₁And θ₃Stray
It can be measured with reference to the portion 33. Also, of the head 2
At the time of mounting, with the straight portion 33 as a reference surface, the head 2
The amount of protrusion and posture can be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drum device suitable for a recording or reproducing device such as a VTR for recording or reproducing a signal on a tape by a head mounted on the rotary drum.

[0002]

2. Description of the Related Art FIG. 3 is a perspective view showing a general rotary drum device in a VTR, and FIG. 4 is a plan view thereof. In the figure, 1 is a magnetic tape on which signals are recorded, and 2 is a magnetic head for recording / reproducing signals on / from the magnetic tape 1. Reference numeral 3 denotes an upper cylindrical rotary drum to which the magnetic head 2 is attached, which is supported by a shaft 4 coaxially with a lower fixed drum 5 and is rotatable. The cylindrical fixed drum 5 is provided with a lead 6 that guides the magnetic tape 1 by obliquely winding the magnetic tape 1 at a predetermined incident angle α (see FIG. 5).

The magnetic tape 1 is wound around the peripheral surfaces of the rotating drum 3 and the fixed drum 5 by a predetermined winding angle β by a tape loading mechanism (not shown). At the time of recording / reproducing a signal, the magnetic tape 1 is run at a predetermined speed by a tape driving means (not shown), and the tape width direction is regulated by the lead 6 and the guide posts 7 and 8 before and after the drum.

FIG. 5 is a side development view showing a state in which a tape is wound on a drum. Since the rotating drum 3 is rotating at a high speed, a force f ₁ that tries to lift the magnetic tape ₁ is generated due to the viscosity of air, and an air film is generated between the rotating drum 3 and the magnetic tape 1. Therefore, the regulation force in the tape width direction is reduced, the magnetic tape 1 does not follow the leads 6, and the tape running becomes unstable.

FIG. 6 shows the tape insertion side of the drum in FIG.
FIG. As described above, the air film is present between the magnetic tape 1 and the rotary drum 3, and the magnetic tape 1 floats from the outer peripheral surface of the rotary drum 3. Therefore, the magnetic head 2 is attached so as to project several tens of μm from the outer peripheral surface of the rotating drum 3 so that a good head touch with the magnetic tape 1 can be obtained even if there is an air film. Reference numeral 10 is a head mounting window provided on the rotary drum 3.

FIG. 7 shows the tape eject side of the drum in FIG. 4B.
It is a -B sectional view. The portion of the magnetic tape 1 facing the outer periphery of the fixed drum 5 increases as it goes to the drum exit side, and the air film decreases. Therefore, the magnetic tape 1 and the lower end edge portion of the rotating drum 3 rotating at a high speed come into contact with each other, causing damage to the tape, shaking of the screen, and the like.

As a means for solving these problems, the outer peripheral surface of the rotary drum 3 is tapered. That is, as shown in the sectional view of FIG.
The outer diameter d ₁ and slightly smaller than the outer diameter d ₀ of the fixed drum 5 of the lower end portion, and slightly larger than the outer diameter d ₀ of the fixed drum 5 and the outer diameter d ₃ of the upper end portion of the rotary drum 3 By doing so, a force for pressing the magnetic tape 1 against the lead 6 is generated, and
By making the outer diameter of the lower end portion of the rotating drum 3 smaller than the outer diameter of the fixed drum 5, contact between the lower end edge portion of the rotating drum 3 and the magnetic tape 1 is prevented.

[0008]

However, in the above-mentioned conventional example, since the outer peripheral surface of the rotary drum 3 is tapered, there are the following drawbacks. (1) The outer diameter and the taper shape of the rotating drum 3 must be controlled with high accuracy on the order of μm in order to perform highly accurate recording / reproducing, but the outer peripheral surface of the rotating drum 3 is entirely tapered. Therefore, the outer diameter of the drum differs depending on the measurement position, which makes management difficult. (2) When attaching the magnetic head 2 to the rotating drum 3,
By using the outer peripheral surface of the rotating drum 3 as a reference and using interference fringes generated by an interference objective lens, for example, the protrusion amount and the attitude of the magnetic head 2 are adjusted by the relative amount from the reference surface. Therefore, if the tapered surface is used as the reference surface, it becomes difficult to adjust the magnetic head 2.

Therefore, it is an object of the present invention to provide a rotary drum device which can easily control the outer diameter and taper shape of the rotary drum and can accurately mount and adjust the head. To do.

[0010]

In order to solve the above-mentioned problems, a rotary drum device according to the present invention comprises a rotary drum equipped with a head for recording or reproducing a signal on a tape which is a recording medium, and the tape. A fixed drum arranged coaxially with the rotary drum and having a lead for guiding to travel at an incident angle, and the outer peripheral surface of the rotary drum sliding with the tape has two taper portions and two taper portions. It consists of a straight part sandwiched between two tapered parts.

The lower end diameter of the rotary drum is smaller than the fixed drum diameter, and the upper end diameter of the rotary drum is larger than the fixed drum diameter.

Further, the straight portion is provided near the upper portion of the head.

It is preferable that the outer peripheral surface of the rotary drum has a groove portion for adjusting the air film amount, and the straight portion is provided immediately below the groove portion.

Further, a plurality of groove portions for adjusting the amount of air film are provided on the outer peripheral surface of the rotary drum, and the straight portion is provided between the groove portion at the lowest position of these groove portions and the groove portion immediately above. Good.

[0015]

According to the present invention constructed as described above, the outer diameter of the straight portion on the outer peripheral surface of the rotary drum can be measured to accurately measure the outer diameter of the drum at a fixed position. The outer diameter of the drum can be easily controlled, and the taper angle of the taper portion can be easily controlled if the straight portion is used as a reference.

When the head is attached, the straight portion, which is a cylindrical surface, is used as a reference surface,
It is possible to accurately adjust the protrusion amount and posture of the head, and by providing the straight portion between the two tapered portions in the vicinity of the upper portion of the head, the head mounting accuracy is improved and the working time is also increased. Can be shortened.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a rotary drum device of a VTR will be described below with reference to FIGS. The entire structure of the rotary drum device according to this embodiment and the loading and driving of the tape are substantially the same as those of the general rotary drum device described with reference to FIGS. 3 and 4.

First, FIG. 1 is a view best showing the features of the rotary drum device in the first embodiment, and is a cross-sectional view of the main part showing the tape winding state of the drum.

Reference numeral 1 is a magnetic tape on which a signal is recorded, 2 is a magnetic head for recording / reproducing signals on the magnetic tape 1, 3 is an upper rotary drum to which the magnetic head 2 is attached, and 5 is a rotary drum 3. A lower cylindrical fixed drum arranged coaxially with the magnetic tape 1 and the magnetic tape 1 at a predetermined incident angle α.
(See FIG. 5) Leads provided on the fixed drum 5 for winding and guiding obliquely, 9 are a plurality of grooves provided on the outer peripheral surface of the rotating drum 3 for adjusting the air film amount, and 10 are rotating members. It is a head mounting window provided on the drum 3.

The outer peripheral surface of the rotary drum 3 has a first taper portion 31 (height h ₁ ) on the lower end side and a second taper portion 3 on the upper end side.
2 (height h ₃ ), a straight portion 33 (height h ₂ ) provided between the first taper portion 31 and the second taper portion 32
It is composed by.

First taper portion 31 and second taper portion 32
The straight portion 33 provided between the rotary drum 3 and the
It serves as a reference surface for controlling the outer diameter and the taper shape and for mounting the magnetic head 2.

That is, the cylindrical straight portion 33 is h₂of
The outer diameter dimension is constant with respect to the width,
Diameter d₂Can be measured easily and with high accuracy.
The outer diameter of 3 can be easily controlled. Also, the first
Taper angle θ of taper portion 31 of ₁And the second taper portion 32
Taper angle θ₃High precision based on the straight part 33
Since it can be measured every time, it can be easily managed.
Furthermore, when the magnetic head 2 is attached, the cylindrical surface
By using the plate portion 33 as a reference surface,
It is possible to accurately adjust the protrusion amount and the posture of the head 2.

The straight portion 33 is particularly suitable for the rotary drum 3.
Is located above the head mounting window 10 and below the lowest groove 9a. This is because it is necessary to avoid the head mounting window 10 in order to measure the outer diameter, and it is preferable to provide the straight portion 33 as close to the magnetic head 2 as possible as a reference surface for head mounting. As a result, the mounting accuracy of the magnetic head 2 can be improved and the working time can be shortened.

Further, the first and second taper portions 31 and 3
Since the taper amount of 2 is extremely small, the straight portion 33
Although it is difficult to see the boundary between the straight portion 33 and the straight portion 33, the straight portion 33 is directly below the groove portion 9a at the lowest position.
The position of can be easily confirmed visually.

The length h ₂ of the straight portion 33 should be such that the outer diameter can be measured and can be used as a reference surface.
For example, it is desirable that 0.5 mm ≦ h ₂ ≦ 1.5 mm.

The outer diameter d ₁ of the lower end of the first tapered portion 31 is
It is slightly smaller than the outer diameter d ₀ of the fixed drum 5. For this reason, even if the air film decreases on the tape ejection side of the drum, the magnetic tape 1 does not come into contact with the lower edge portion of the rotating drum 3, and there is no concern that tape scratches or screen shake will occur.

The difference between the outer diameters d ₁ and d ₀ (d ₀ -d ₁ )
For example, in the case of 8 mm VTR, it is desirable to exceed 0 to about 10 μm, and if it is set too large, the magnetic tape 1 may be scratched at the upper end of the fixed drum 5.

The outer diameter d ₃ of the upper end of the second taper portion 32 is
It is slightly larger than the outer diameter d ₀ of the fixed drum 5. As a result, the magnetic tape 1 has the second taper portion 32.
A downward force F ₀ is received from the vehicle, and a component force F ₁ that tries to press the lead 6 is generated, so that the vehicle can run stably along the lead 6.

The angle θ ₃ of the second taper portion 32 is set to an angle smaller than the angle θ _{1 of} the first taper portion 31. For example, in the case of 8 mm VTR, 0.01 ° ≦ θ ₃ ≦
A range of 0.1 ° is desirable. If the angle θ ₃ is too large,
The deformation of the magnetic tape 1 becomes large, and the head touch with the magnetic head 2 deteriorates.

The angle θ _{3 is set} to a large value and the lead 6
The width h of the straight portion 33
By lengthening the _2, tape deformation in the vicinity of the magnetic head 2 is gentle, it is possible to maintain good head touch.

Next, FIG. 2 is a cross-sectional view of an essential part showing a tape winding state of a drum in the second embodiment. In this example,
Since the straight portion 33 is provided between the groove portion 9a at the lowermost position and the groove portion 9b immediately above the straight portion 33, the range of the straight portion 33 can be visually confirmed more accurately as compared with the first embodiment. The outer diameter of the rotary drum 3 and the magnetic head 2 can be adjusted more easily.

As described above, according to this embodiment, the outer diameter of the rotary drum 3 is made larger by the straight portion 33 between the first taper portion 31 and the second taper portion 32 on the outer peripheral surface of the rotary drum 3. In addition, it is possible to manage the taper shape with high accuracy and to accurately attach and adjust the magnetic head 2. In addition to this, in the present embodiment, the outer peripheral surface of the rotary drum 3 is the first
Since the taper portion 31 and the second taper portion 32 form a two-step taper, the pressing force against the lead 6 of the magnetic tape 1 by the second taper portion 32 and the magnetic tape 1 by the first taper portion 31 are generated. It is possible to effectively prevent contact with the lower end edge portion of the rotary drum 3 in the optimum state.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various effective modifications and applications are possible based on the technical idea of the present invention. For example, it goes without saying that the dimensions, angles, and the like of the respective parts in the above-described rotary drum device are optimally set based on various specifications of the rotary drum device, tape, and the like.

[0034]

As described above, according to the present invention,
By providing two tapered portions and a straight portion between them on the outer peripheral surface of the rotating drum, highly accurate control of the outer diameter and the tapered shape of the rotating drum is extremely achieved without impairing the effect of the conventional drum having a taper. In addition to being easy, it is possible to attach and adjust the head extremely accurately, and it is possible to obtain a better head touch than in the conventional case.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing a tape winding state of a drum in a first embodiment in which the present invention is applied to a rotary drum device of a VTR.

FIG. 2 is a sectional view of an essential part showing a tape winding state of a drum according to a second embodiment of the present invention.

FIG. 3 is a perspective view of a conventional general rotary drum device.

FIG. 4 is a plan view of the rotary drum device.

FIG. 5 is a side development view showing a tape winding state of a drum in the rotary drum device.

FIG. 6 is a cross-sectional view taken along the line AA of FIG. 4, showing the tape insertion side of the drum.

FIG. 7 is a cross-sectional view taken along the line BB of FIG. 4, showing the tape ejection side of the drum.

FIG. 8 is a sectional view of a main part of a conventional rotary drum device.

[Explanation of symbols]

 1 Magnetic Tape 2 Magnetic Head 3 Rotating Drum 5 Fixed Drum 6 Lead 9 Air Film Adjusting Groove 10 Head Mounting Window 31 First Tapered Part 32 Second Tapered Part 33 Straight Part

Claims (5)

[Claims] 1. A rotary drum having a head for recording or reproducing a signal on a tape as a recording medium, and a lead for guiding the tape to travel at a predetermined incident angle, and coaxial with the rotary drum. A rotary drum device, comprising: a fixed drum arranged; and an outer peripheral surface of the rotary drum, which slides on the tape, comprising two tapered portions and a straight portion sandwiched between the two tapered portions. . 2. The rotary drum according to claim 1, wherein a lower end diameter of the rotary drum is smaller than a diameter of the fixed drum, and an upper end diameter of the rotary drum is larger than a diameter of the fixed drum. apparatus. 3. The rotary drum device according to claim 1, wherein the straight portion is provided in the vicinity of above the head. 4. An outer peripheral surface of the rotary drum has a groove portion for adjusting an air film amount, and the straight portion is provided immediately below the groove portion.
The rotating drum device described. 5. The outer peripheral surface of the rotary drum has a plurality of groove portions for adjusting the air film amount, and the straight portion is provided between the groove portion at the lowest position and the groove portion immediately above the groove portions. The rotary drum device according to claim 1, 2 or 3, wherein.