JPS6122472Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a structure for mounting a pulse generator in a recording/reproducing apparatus such as a VTR.

In a helical scan type VTR using a rotating head, as shown in FIG. 1, a rotating drum 3 is fixed to a rotating shaft 1 and has heads 2a and 2b.
is provided, and a lower drum 4 is fixedly provided below it. Also, this rotating drum 3
A pulse generator 5 is provided for detecting the rotation of. The pulse generator 5 consists of a magnet 6 fixed to the bottom surface of the rotating drum 3, a rod-shaped iron core 7 fixed to the lower drum 4 and arranged at a predetermined gap from the magnet 6, and a coil 8 wound around it. and a coil bobbin 9 fitted and fixed to the iron core 7. In the above configuration,
When the rotating drum 3 rotates together with the magnet 6,
When the magnet 6 passes above the iron core 7, a pulse signal can be obtained from the coil 8 by interlinking the iron core 7 with the magnetic flux.

Then, the iron core 7 and bobbin 9 are attached to the lower drum 4.
Conventionally, the methods shown in FIGS. 2A and 2B have been used to fix the wire. First, as shown in FIG. 2A, the lower drum 4 is positioned and placed upside down on the jig 10. Next, the iron core 7 is inserted from above into the insertion hole 11 provided at the bottom of the lower drum 4, positioned, and fixed in the insertion hole 11 with adhesive. Note that 12 is a recess into which the flange 9a of the bobbin 9 is fitted. Next, after placing the lower drum 4 with the iron core 7 fixed on the jig 10 as shown in FIG.
and the iron core 7 and insert the flange 9 into the recess 12.
Fit a. At this time, the iron core 7 and the insertion hole 13 are fixed with an adhesive.

In the conventional fixing method described above, the iron core 7 is fixed to the lower drum 4 and bobbin 9 via adhesive, so there is a slight gap between the insertion holes 11, 13 and the iron core 7. It is occurring. For this reason, iron core(7)
is sometimes fixed at an angle, making it extremely difficult to achieve positioning accuracy. Furthermore, it is difficult to correct the positional accuracy after the adhesive has hardened. Furthermore, since adhesive is used and the work is done from both sides of the lower drum 4, work efficiency is poor and automation is not possible. There is a risk of adhesive getting into your eyes while working. This caused problems such as:

The present invention can solve the above problems, and embodiments of the present invention will be described below with reference to the drawings.

3 to 5 show a first embodiment of the bobbin 15 according to the present invention. The bobbin 15 is made by integral molding of synthetic resin such as polycarbonate, and has flanges 16a, 16b on the central shaft.
The central shaft portion is provided with a protrusion 17 extending downward, and the central shaft portion and the protrusion 1
An insertion hole 18 is provided through the flange 7. A coil 8 is wound between the flanges 16a and 16b. The protrusion 17 is divided into four parts as shown in the figure.

The bobbin 15 with the above configuration is shown in Fig. 6 A, B, and C.
It is attached to the lower flange 4 as shown in FIG.

First, as shown in FIG. 6A, the protrusion 17 is elastically fitted into the fitting hole 19 provided in the lower drum 4. As a result, each divided portion of the protrusion 17 is slightly tilted toward the center against its elasticity. As a result, the diameter of the insertion hole 18 of the protrusion 17 becomes slightly shorter. Next, as shown in FIG. 6B, the rod-shaped iron core 7 is inserted into the insertion hole 18 from above and fitted. In this case iron core 7
When the lower end of the protrusion 17 reaches the protrusion 17, the protrusion 17 is press-fitted while pushing the divided portions apart. As a result, the iron core 7 is firmly press-fitted and fixed in the fitting hole 19 together with the protrusion 17 as shown in FIG. 6C.

7 to 10 show the second to fifth embodiments, and show a modification of the structure of the protrusion 17 and a state in which the bobbin 15 is attached to the lower drum 4, respectively. In both cases, the protrusion 17 and the iron core 7 are elastically press-fitted into the fitting hole 19 of the lower drum 4 and fixed. In the first to fifth embodiments, the outer diameter φ ₁ of the protrusion 17 is the same as that of the fitting hole 1 in order to achieve the above-mentioned press-fitted state.
It is formed slightly larger than the inner diameter _φ2 of 9.
Further, the iron core 7 may be press-fitted by a press.

In the present invention, a coil 8 is wound around the center shaft of the bobbin, and a protrusion 17 is provided extending downward from the center shaft to give this protrusion elasticity in the radial direction. A through hole 18 passing through the protrusion is provided, and the protrusion is fitted into a hole 19 provided in the lower drum 4 that is slightly smaller in diameter than the protrusion, resisting the elasticity, and a bar-shaped iron is inserted into the through hole. This is a pulse generator in which a core 7 is inserted through the pulse generator, and the rod-shaped iron core is disposed at a position close to and opposite to the rotation locus of a magnet 6 provided on a rotating drum 3.

Therefore, according to the present invention, by elastically fitting the protrusion 17 into the hole of the lower drum, the diameter of the insertion hole 18 provided in the protrusion is reduced, and in this state, the iron core 7 is inserted. Since the iron core 7 is inserted while expanding the insertion hole, it is possible to fix the iron core 7 very firmly, so that it will not become misaligned due to changes over time. Furthermore, the positional accuracy of the bobbin and the iron core can be increased. Furthermore, since no adhesive is used, the number of assembly steps can be greatly reduced, and accidents caused by adhesives are eliminated, making work safer. Furthermore, it can be easily disassembled for repair or replacement. Furthermore, since the drum can be assembled by simply working from above while it is placed upright on the jig, workability is improved and automatic assembly is also possible.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional side view of a drum to which the present invention can be applied, Fig. 2 A and B are cross-sectional side views showing a conventional method of attaching a pulse generator, and Figs. 3 to 5 are a first embodiment of the present invention. Examples are shown. Figure 3 is a sectional side view, Figure 4 is a side view, Figure 5 is a bottom view, Figure 6 is a sectional side view showing the assembly process, and Figures 7 to 10 are 2 to 5. In each figure, A is a cross-sectional side view, B is a side view, C is a bottom view, and D is a cross-sectional side view of the main part showing the state of attachment to the lower drum. In addition, in the symbols used in the drawings, 4...
...Lower drum, 5...Pulse generator, 7...
Iron core, 15...Bobbin, 17...Protrusion, 18...
Insertion hole 19 is a fitting hole.

Claims (1)

[Scope of utility model claims] While winding the coil around the central shaft of the bobbin,
A protrusion extending downward from the central shaft portion is provided so that the protrusion has elasticity in the radial direction, a through hole passing through the central shaft portion and the protrusion is provided, and the protrusion is provided on the lower drum. The rod-shaped iron core is fitted into a hole slightly smaller in diameter than the diameter of the protruding portion resisting the elasticity, and the rod-shaped iron core is inserted into the through-hole, and the rod-shaped iron core is provided on a rotating drum. The pulse generator is placed in close opposition to the pulse generator.