JPH0333922Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape guide drum, and in particular, an object of the present invention is to provide a tape guide drum that can improve the mounting accuracy of a rotary transformer and can be manufactured efficiently.

Generally, in the tape guide drum of a VTR device, video signals are transferred between the magnetic head attached to the rotating upper rotating drum and the lower fixed drum that is coaxially installed and fixed below the upper rotating drum. This is performed by a rotary transformer consisting of a pair of rotary transformer halves on the rotating side and the fixed side, which are fixed in close proximity to each other in a non-contact state to the upper rotating drum and the lower fixed drum, respectively.

As shown in FIG. 1, in the conventional tape guide drum 1, the annular adhesive surface 3a of the flywheel 3 fixed to the upper rotating drum 2 (indicated by the two-dot chain line)
A rotating side rotary transformer half 4a of the rotary transformer 4 is fixed to the rotary transformer 4.

A shaft 5, which is a rotating shaft, is fitted and fixed into the center hole 3b of the flyhole 3. The lower fixed drum 6 supports the shaft 5 via two bearings 7 and 8, and a fixed rotary transformer half 4b is fixed to the annular mounting surface 6a. When fixing the rotary transformer halves 4a and 4b, in order to use the surface area of the rotary transformer halves 4a and 4b more effectively within the limited installation space, the respective adhesive surfaces 3a and 6a are coated with a two-component acrylate adhesive, for example. After applying the adhesive 10, the rotary transformer halves 4a,
4b was pressed against the adhesive surfaces 3a and 6a and fixed by adhesive.

However, due to the thickness of the adhesive layer when the adhesive 10 is cured, the rotary transformer halves 4a, 4b
When the flyhole 3 is assembled to the lower fixed drum 6 after adhesive fixation, the distance between the opposing rotary transformer halves 4a and 4b is determined by the variation in the thickness of the adhesive layer. It had the disadvantage of being

If the thickness of the adhesive layer on the adhesive surfaces 3a and 6a is uneven in this way, when the upper rotating drum 2 and the flywheel 3 rotate, the rotary transformer half 4
An axial surface runout occurs in a and 4b, and the above-mentioned separation dimension changes, resulting in a change in the excitation inductance. Therefore, in order to maintain the desired excitation inductance, the amount of application of the adhesive 10, the viscosity, and the pressing force at the time of bonding are adjusted so that the distance between the rotary transformer halves 4a and 4b becomes a predetermined dimension. Layer thickness and rotary transformer halves 4
It was necessary to control the mounting heights of parts a and 4b, and there was a drawback that assembly was troublesome. In addition, several types of spacers 11 with different thicknesses are prepared, and the mounting height dimension of the rotary transformer half body 4b and the surface runout of the rotary transformer half bodies 4a, 4b during rotation are measured, and the thickness is determined according to the measured values. A spacer 11 was also installed between the inner ring 7a of the bearing 7 and the flywheel 3 to correct the separation dimension.
The drawback was that the adjustment was extremely troublesome.

The present invention eliminates the above-mentioned drawbacks and will be explained below with reference to FIG.

Figure 2 shows the tape guide drum 12 of the present invention.
1 is a half-longitudinal cross-sectional view of one embodiment of the present invention, and the same reference numerals are given to the same parts as in FIG.

In FIG. 2, the configurations of the rotary transformer attachment parts of the flywheel 13 fixed to the upper rotating drum 2 and the lower fixed drum 14 are the same, so only the attachment parts on the flywheel 13 side will be explained below, and the lower fixed A description of the mounting portion on the drum 14 side will be omitted by adding the same suffix to the reference numeral 14. On the rotary transformer mounting portion side of the flywheel 13, there is a second mounting surface 13a in the form of an annular plane and an annular adhesive surface (second stepped portion) 1 that is recessed one step from the mounting surface 13a.
3b is formed with high precision by machining.
Further, a plurality (three or more) of second through holes 13d penetrating from the adhesive surface 13b to the upper surface 13c of the flywheel 13 are formed at equal intervals on the same radius.

When attaching the rotary transformer half (the other half) 4a to the flywheel 13, attach the rotary transformer half 4a to the mounting surface 13 of the flywheel 13.
For example, an appropriate amount of ultraviolet curing adhesive 15 is injected into the through hole 13d from the upper surface 13c side of the flywheel 13 while directly abutting the flywheel 13. If ultraviolet rays are irradiated from the through hole 13d in this state, the adhesive 15
is cured in a few minutes, and the rotary transformer half 4a is in contact with the mounting surface 13a of the flywheel 13, and while it is positioned, the adhesive 15 is applied to the adhesive surface 1.
It is adhesively fixed to 3b. At this time, the rotary transformer half 4a does not require controlling the amount of adhesive 15 applied, the viscosity, or the pressing force of the jig, etc., as in the conventional case.
Moreover, it is adhesively fixed to a predetermined mounting position with high accuracy without being affected by the thickness of the adhesive layer.

The lower fixed drum 14 is connected to the flywheel 13 mentioned above.
Similarly, rotary transformer half (one half) 4
a first mounting surface 14a that b directly contacts without intervening an adhesive layer; an adhesive surface (first stepped portion) 14b formed at a lower position than this mounting surface 14a;
It has a second through hole 13d that penetrates the lower fixed drum 14 and opens to the adhesive surface 14b. Therefore, the rotary transformer half 4b is fixed in place by injecting adhesive into the through hole 14d while being positioned in direct contact with the mounting surface 14a.

When using the above flywheel 13 assembled to the lower fixed drum 14 to which the rotary transformer half body 4b is adhesively fixed in the same manner as above, an axial preload is applied to the shaft 5 so that the shaft of the bearings 7 and 8 is By suppressing directional wobbling, the distance between the rotary transformer halves 4a and 4b is prevented from varying due to variations in the bearings 7 and 8 during rotation. In addition, the width accuracy of the inner and outer rings of bearings 7 and 8 and the variation in axial travel when preload is applied are measured individually using an automatic measuring machine before assembly, and the bearings are sorted according to the range of measured values and then installed on the flywheel. 13 mounting surface 13a to the upper surface 7b of the bearing 7
Depending on the dimension from the end surface 13e that comes into contact with the lower fixed drum 14 and the dimension from the stepped portion 14e of the lower fixed drum 14 that the bearing 7 comes into contact with to the mounting surface 14a, the separation dimension is used appropriately so that it falls within a predetermined size range. Therefore, the step of adjusting the separation dimension using the conventional spacer 11 is not necessary, and the mounting can be performed with high precision.

Furthermore, for example, when an ultraviolet curing adhesive is used as the adhesive, there is no need to press the rotary transformer half 4a against the adhesive surface 13b using a jig or the like, compared to a conventional two-component acrylate adhesive. Since the adhesive can be cured and bonded simply by irradiating ultraviolet rays through the through hole 13d, automation of the process of bonding the rotary transformer halves becomes possible. In addition, as described above, the rotary transformer halves 4a and 4b are selectively connected to the through holes 1.
When bonding and fixing the adhesive 15 to the adhesive surfaces 13b and 14b via 3d and 14d at three or more locations, sufficient adhesive strength can be obtained.

As mentioned above, the tape guide drum according to the present invention has a pair of rotary transformers, a lower fixed drum, and a flywheel, and the lower fixed drum is one half of the rotary transformer. a first mounting surface that is directly abutted and mounted without an adhesive layer; a first step portion formed on the lower fixed drum side continuous with the first mounting surface; a first through hole passing through the lower fixed drum; the flywheel has a second mounting surface that directly contacts and attaches the other half of the rotary transformer without an adhesive layer; a second step portion formed on the lower fixed drum side continuous with the mounting surface; and a second through hole penetrating the flywheel in the second step portion, the first mounting surface. and one half of the rotary transformer are brought into direct contact without using an adhesive layer,
Adhesive is injected into the first stepped portion through the first through hole to adhesively fix one half of the rotary transformer to the lower fixed drum, and the second mounting surface and the other half of the rotary transformer are bonded to each other. The two halves are brought into direct contact without using an adhesive layer,
The other half of the rotary transformer is adhesively fixed to the flywheel by injecting adhesive into the second stepped portion through the second through hole, and has the following features.

That is, in the present invention, the rotary transformer half is positioned in direct contact with the first and second mounting surfaces without using an adhesive layer, and in this state, the adhesive is injected into the first and second through holes. is filled between the rotary transformer half and the first and second step portions, and the rotary transformer half can be adhesively fixed, so the rotary transformer half can be assembled accurately and efficiently. Therefore, unlike in the past, the mounting height of the rotary transformer is not affected by the thickness of the adhesive layer, and therefore there is no need to adjust the amount of adhesive applied, viscosity, pressing force, etc. It is possible to eliminate surface run-out during rotation due to uneven application of the rotary transformer, improve the mounting accuracy of the rotary transformer, and stabilize the state of high precision. It is possible to improve the excitation inductance of the rotary transformer, and there is no need to adjust the distance between the rotary transformers using a spacer.Furthermore, it is possible to automate the bonding process by using an ultraviolet curing adhesive as the adhesive. It has features such as being able to be produced efficiently.

[Brief explanation of drawings]

FIG. 1 is a half-longitudinal sectional view of a conventional tape guide drum, and FIG. 2 is a half-longitudinal sectional view of an embodiment of the tape guide drum of the present invention. 1, 12... Tape guide drum, 2... Upper rotating drum, 3, 13... Flywheel, 4...
... Rotary transformer, 4a, 4b ... Rotary transformer half, 5 ... Shaft, 6, 14 ... Lower fixed drum, 7, 8 ... Bearing, 10 ... Adhesive, 11 ... Spacer, 13a, 14a ... ...Mounting surface, 13b, 14b...Adhesive surface, 13d, 14
d...Through hole, 15...Adhesive (ultraviolet curing type).

Claims (1)

[Claims for Utility Model Registration] A tape guide drum having a pair of rotary transformer halves, a lower fixed drum, and a flywheel, the lower fixed drum having one half of the rotary transformer covered with an adhesive layer. a first mounting surface that is directly abutted and mounted without intervening; a first step portion formed on the lower fixed drum side continuously with the first mounting surface; a first through hole passing through the drum; the flywheel has a second mounting surface to which the other half of the rotary transformer is directly abutted and mounted without an adhesive layer; a second step portion formed on the lower fixed drum side continuously with the first mounting surface, and a second through hole passing through the flywheel in the second step portion; One half of the transformer is brought into direct contact without an adhesive layer,
Adhesive is injected into the first stepped portion through the first through hole to adhesively fix one half of the rotary transformer to the lower fixed drum, and the second mounting surface and the other half of the rotary transformer are bonded to each other. The two halves are brought into direct contact without using an adhesive layer,
A tape guide drum characterized in that the other half of the rotary transformer is adhesively fixed to the flywheel by injecting an adhesive into the second stepped portion from the second through hole.