JPS6323784Y2 - - Google Patents

Description

[Detailed Description of the Invention] A head drum device in a helical scan type VTR is constructed as shown in FIG. 1, for example.

That is, in FIG. 1, reference numeral 1 indicates a lower drum fixed to the chassis, and 2 indicates an upper drum rotated at a field frequency. (not shown), and inside thereof, a shield plate 3, a circuit board 4 made of a printed circuit board, a shield plate 5, and an electrode board 6 made of a printed board are laminated in this order.

The substrates 4 and 6 are circular in shape. On the upper surface of the substrate 4, elements such as an IC constituting the head amplifier 7 are mounted, and on the lower surface, a contact 8 is provided, and this contact 8 is formed on the upper surface of the substrate 6. It is arranged to be in contact with the wiring pattern 9. Further, the shield plate 5 is formed of a copper material in a double circular shape, and the board 4
It is soldered to the ground pattern on the bottom side of the .
Further, the shield plate 3 is formed into a cup shape from copper material, and these shield plates 3, 5 and substrates 4, 6
is screwed to drum 2.

A head and a rotary transformer (not shown) are connected to the board 6, and the playback output of the playback head is sent to the amplifier 7 via a line from the head → board 6 → wiring pattern 9 → contact 8 → board 4 → amplifier 7. It is supplied and amplified, and further, the amplifier 7 → the board 4
→Contact 8→Wiring pattern 9→Substrate 6→Rotary transformer line.

At this time, the amplifier 7 is shielded by the shield plates 3 and 5, and among the contacts 8, the input side contact and the output side contact are shielded and separated by the shield plate 5. Further, the substrate 4 is a double-sided substrate, and among its circuit patterns, the ground pattern is made as wide as possible to enhance the shielding effect.

The head drum device is constructed as described above.

However, in this case, the shield plate 3 has a complicated shape according to the circuit pattern of the printed circuit board 4, and the accuracy of the through holes in the circuit board 4 becomes a problem when soldering to the ground pattern. The shield plate 3 had to be assembled in several parts.

In addition, the shield plates 3 and 5 must be made of copper plates with a thickness of, for example, 0.3 mm for electromagnetic shielding, but this increases the weight, and when installed inside the rotating drum 2, this dynamic balance becomes a problem. It was hot.

This invention attempts to solve these problems.

Let's explain one example below.

The shield plate 3 is formed into a double cup shape, as shown in FIGS. 2 to 4, for example, and includes an upper bottom shield plate part 31, an outer annular shield plate part 32, and an inner annular shield plate part 33. , and a radial shield plate portion 34. Further, the shield plate parts 31 and 34 are formed with holes 35 through which screws are passed when screwing the shield plates 3 and 5 and the substrates 4 and 6 to the drum 2. A through hole 36 is formed into which a position adjustment pin is inserted.

The entire shield plate 3 is integrally formed by a heat-resistant resin mold, for example, an ABS resin mold, and its entire surface is electroless plated (chemically plated), and then, for example, copper plated. As a result, a copper plating layer with a thickness of, for example, 30 μm is formed on the entire surface.

Further, as shown in FIGS. 5 to 7, for example, the shield plate 5 is composed of an outer annular shield plate part 52, an inner annular shield plate part 53, and a radial shield plate part 54, and further includes: Through holes 5 corresponding to the through holes 35 and 36 are provided in the shield plate parts 53 and 54.
5 and 56 are formed, and the shield plate portion 5
3 and 54 are formed with notches 57 to prevent them from coming into contact with patterns other than the ground pattern of the substrate 4.

Similar to the shield plate 3, this shield plate 5 is also integrally formed as a whole by molding of ABS resin, and a copper plating layer is formed on the entire surface thereof.

Then, as shown in FIG. 8, the printed circuit board 4
The shield plate 5 is laminated on the lower surface of the shield plate 5, and at this time, the positioning pin 41 is inserted into the through hole of the shield plate 5.
6 and the through hole of the substrate 4, and the positions of the substrate 4 and the shield plate 5 are regulated. In this state, the shield plate 5 is fixed to the substrate 4 by soldering, for example, several places on the inner peripheral surface of the shield portion 52 to the ground pattern of the substrate 4.

Further, the shield case 3 is stacked on the upper surface of the substrate 4, and its position is regulated by pins 41. In this state, the shield plates 3 and 5 and the substrate 4 are mounted on the drum 2. Note that this mounting is performed using screws passing through the through holes 35 and 55. Further, the substrate 6 is separately mounted on the drum 2 in advance.

The head drum device is assembled as described above, but in this case, according to this invention, the shield plates 3 and 5 are formed by molding resin and plating, so even complex shapes can be formed. Therefore, there is no need to separate and assemble them, and they can be formed in one piece.Furthermore, since the shield plates 3 and 5 are molded, they are lightweight, and since the whole can be formed in one piece, the dynamic balance does not vary. It can be done stably without any problems.

Furthermore, the shield parts 31 to 33, 52 provide a shield from the outside, the shield parts 34, 54 provide a shield between channels, and the shield part 55 provides a shield between the input side and the output side. advantageous to

In addition, when replacing the rotating drum, the electrode board and rotary transformer are connected by lead wires, but the circuit board and electrode board are only in pressure contact with each other; It can be easily removed from the rotating drum. Therefore, when replacing the rotary drum, the circuit board can be easily replaced with a new rotary drum, so there is no need to replace the circuit board, and repair costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an example of this invention, Fig. 2 is a plan view of a part of it, Fig. 3 is a bottom view thereof, Fig. 4 is a sectional view taken along line A-A, and Fig. 5 is A plan view of another example of this invention, FIG. 6 is a bottom view thereof, and FIG. 7 is a sectional view taken along the line B-B.
FIG. 8 is a perspective view for explaining this invention. 1 and 2 are drums, 3 and 5 are shield plates, 4 is a circuit board, and 6 is an electrode board.

Claims (1)

[Scope of utility model registration request] A rotating drum device having a rotating magnetic head includes a circuit board having electronic components attached to at least one surface and a plurality of electrodes provided on the other surface, and a plurality of circuit boards each corresponding to the plurality of electrodes on one surface. The rotary drum portion includes an electrode substrate provided with electrodes and transmitting input/output signals of the circuit board, and a shield member having a cylindrical shape and having a shield plate portion on the inner surface thereof for selectively shielding between the plurality of electrodes. The shield member is a rotary drum device in which a conductive layer is plated on the entire surface of a molded resin.