JPH0480559B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to tuners for television receivers and
This relates to shield devices used in CATV converters and the like.

BACKGROUND ART In recent years, as television receivers have become multi-channel, CATV converters and double super tuners have become popular.

These systems have two local oscillators and the oscillation power is large, so spurs due to mutual interference between the local oscillators and leakage to the input terminals are a problem, so it is especially important to shield the block of the first local oscillator. At the same time, the entire structure was covered with a shield plate from above, and an outer cover was fitted from above.

Hereinafter, the conventional shield device as described above will be explained with reference to the drawings. FIG. 2 shows a conventional shielding device. In FIG. 2, 1 is a plan view and 2 is a sectional view. 1 is a partition plate that shields each circuit block in the tuner, 2 is a shield lid that shields the local oscillation circuit block, 3 is solder for soldering the joint between the partition plate 1 and the shield lid 2, and 4 is the entire circuit block. 5 is an inner shield plate that covers the casing, and 5 is an outer cover that covers the entire tuner case.

In the shield device configured as described above, a fairly strict shield is required to prevent leakage from the local oscillator, and generally only the outer cover 5 is used, as shown in 2 in Figure 2. Instead, the inner shield plate 4 covers the entire circuit block.
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Furthermore, if this is done alone, the degree of adhesion between the inner shield plate 4 and the partition plate 1 will deteriorate over time, and if a heat shock is applied, the shielding effect will deteriorate due to repeated expansion and contraction, creating a gap. This causes a problem in that poor contact occurs and the oscillation frequency changes, causing noise on the screen of the television receiver. Therefore, generally, a shield lid 2 is further provided only on the local oscillator block.
It was fitted into a local oscillator block, solder 3 was applied to the joint, and an inner shield plate 4 and an outer cover 5 were placed over it.

Problems to be Solved by the Invention However, in the above configuration, it is necessary to prepare and fit the shield lid 2, and then manually solder it to the partition plate 1, which slows down the production process. The problem was that it took a lot of man-hours.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a shield device that can provide an effective shield without requiring any man-hours such as soldering work.

Means for Solving the Problems In order to achieve this object, the shielding device of the present invention has a cut-out part in the inner shield plate that contacts the upper part of the partition plate to provide a spring effect. It is made up of things.

Effect With this configuration, when the outer cover is placed on the inner shield plate, the inner shield plate is pressed against the upper part of the partition plate, and due to the spring effect of the cut-and-raised part, the inner shield plate is completely in contact with the upper part of the partition plate. There is no need to separately provide a shield lid and solder it, and good contact can be maintained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a plan view of a shield device 1 in an embodiment of the present invention, 2 a side sectional view of an inner shield plate, and 3 a side sectional view of the shield device. In FIG. 1, 1 is a partition plate that separates each local oscillator circuit block 7a to 7e in the tuner, and 2 is a hemispherical round projection (provided on the inner shield plate 4) provided approximately at the center of each local oscillator block 7a to 7e. Dowels) and 3 are tongue pieces cut and raised from the inner shield plate 4, which are cut and raised in the direction of the partition plate 1 and are bent. 4 is an inner shield plate, 5 is an outer cover, and 6 is a board on which parts are mounted and wired.

In the shield device configured as described above, FIG. 1 shows each local oscillator circuit block 7a to
This figure shows the state in which the inner shield plate 4 is placed over the partition plate 1 that divides the local oscillator circuit blocks 7a to 7e. Indicates the condition. Further, a round projection 2 projecting upward is provided near the center of the local oscillator circuit blocks 7a to 7e. Figure 1 2
1 is a side cross-sectional view of the inner shield plate 4, and the round projections 2 and the cut and raised portions 3 are punched out from the inner shield plate 4. Figure 1 3 shows an outer cover 5 on top of the inner shield plate 4.
In the cross-sectional view of the fitted state, the upper part of the round protrusion 2 is 5
Since it is pressed downward by the outer cover, the tip of the cut-and-raised part 3 comes into close contact with the upper part of the partition plate 1, and the state of contact is sufficiently maintained by the spring effect.

As described above, according to the shield device of this embodiment, the inner shield plate 4 is provided with the cut-and-raised part 3 and the round-shaped protrusion 2, and the outer cover 5 is used to press down the protrusion part. Since the tip of the cut portion is sufficiently pressed against the upper part of the partition plate 1, a good shielding effect can be obtained.

Effects of the Invention As described above, the present invention allows the inner shield plate to be sufficiently crimped to the partition plate by the cut-outs and round projections provided on the inner shield plate, and the outer cover that is pressed from above. Even if the degree of caulking changes slightly, the spring effect maintains the adhesion, and there is no need to solder a separate shield lid, which can significantly reduce material costs and man-hours. .

[Brief explanation of the drawing]

FIG. 1 is a plan view, a side view, and a sectional view of a shield device according to an embodiment of the present invention, and FIG. 2 is a plan view and a sectional view of a conventional shield device. 1... Partition plate, 2... Round protrusion, 3... Cut and raised, 4... Inner shield plate, 5... Outer cover, 6...
...Board, 7a to 7e...Local oscillator circuit block.

Claims (1)

[Claims] 1. Install a partition plate on the circuit board that separates each local oscillator circuit block in the tuner or converter, provide an inner shield plate to cover the entire circuit board, fit an outer cover on top of the partition plate, and install the local oscillator circuit block on top of the partition plate. At least 1 inch from the inner shield plate to the part where the upper part of the surrounding partition plate and the inner shield plate contact
Bend the cut and raised sections in the direction of the partition plate,
A hemispherical round protrusion is provided near the center of the block from the inner shield plate toward the outer cover, and the round protrusion portion is pressed against the outer cover so that the cut and raised portion is brought into close contact with the upper part of the partition plate. A shield device.