JPH0730277A - Shielding device - Google Patents

Abstract

PURPOSE:To reduce leakage of radiation by forming a recess, which can engage with the base of a twist tab, at the brim of at least one sheet among shield plates. CONSTITUTION:A recess 5a is made, with a width capable of engaging the base 2b of a twist tab 2, at the side of the opening 5 of a shield cover 3. An inner cover 3 and an outer cover 4 are laid on top of each other (arrow (a)) so that the positions of their openings may accord with each other, and then the twist tab 2 of the chassis 1 are inserted into each other's openings 5 and 6. Then, the base 2b of the twist tab 2 are engaged with the recess 5a of the opening 5 by sliding the inner cover 3 in the direction of an arrow (b) to the outer cover 4. Hereby, the opening 6 of the outer cover 4 is shielded partially by the face 3a excluding the recess 5a of the inner cover 3. Then, the outer cover 4 is pressed and the inner cover 3 is welded and fixed to the chassis 1 by twisting the head 2a of the twist tab 2 in the direction of an arrows C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield device used in, for example, a television tuner.

[0002]

2. Description of the Related Art Conventionally, shield devices have been used in a laminated structure for the purpose of preventing leakage of unwanted radiation in high frequency circuit parts such as television tuners. It is desired to reduce it as much as possible.

A conventional shield device will now be described with reference to FIGS. 4 and 5.

Usually, a shield device is formed in a housing by combining a shield case and a shield cover. However, when a high-frequency circuit unit such as a television tuner is mounted therein, the shield cover has a laminated structure. I often do it.

The combined portion of the shield structure and the shield case of this laminated structure has a caulking structure. As shown in FIG. 4, a plurality of, for example, two shield covers 41 and 43 are formed in a slit shape. After overlapping the openings 45 and 47 of the same so that they are aligned (arrow X), the twist tab 50 provided in the shield case 49 is inserted into the openings 45 and 47, and as shown in FIG. The two shield covers 41 and 43 and the shield case 49 are pressure-bonded to each other by twisting in the direction of arrow Y. The twist tab 50 is the head 5
The base portion 50b is formed thin so that the 0a can be easily twisted.

By the way, in the case of this shield device, since the openings 45 and 47 of the shield covers 41 and 43 are aligned and penetrate through the twist tab 50 and twisted, a gap S is formed at the width W2 of the openings 45 and 47. Occurs. The purpose of this shield device is to prevent unnecessary high-frequency signals generated from the high-frequency circuit section, that is, unnecessary radiation, from being emitted to the outside. A large amount of unwanted radiation is emitted to the outside.

However, each shield cover 41, 4
In order to allow the twist tab 50 to pass therethrough, the openings 45 and 47 of 3 need to be formed to match the width of the head portion 50a even if the width of the base portion 50b is narrow, and the width W2 can be made narrower than this. There wasn't.

[0008]

As described above, in the above-described conventional shield device, the width of the opening cannot be made narrower and the leakage of unnecessary radiation is reduced because the twist tab penetrates the opening of the shield plate. There was a problem that I could not.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a shield device capable of reducing leakage of unnecessary radiation after fixing a shield plate.

[0010]

In order to achieve the above-mentioned object, a shield device of the present invention has a structure in which a plurality of shield plates each having a slit-shaped opening are laminated so that the openings are aligned with each other, and these openings are formed. In a shield device in which a twist tab is inserted therethrough and the tab is twisted to integrally fix the shield plates, a base of the twist tab is fitted to an edge of at least one opening of the shield plate. The shield plate is slid with respect to the other shield plate to fit the base of the tab twist into the recess of the opening, and the twist tab is twisted.

[0011]

According to the present invention, the slit-shaped openings of the plurality of shield plates are aligned with each other, the twist tabs are passed through the openings, and then the shield plate having the recesses is slid into the recesses. After fitting the base of the twist tab, twist the twist tab to fix the shield plates together.

As a result, the width of the gap formed after fixing the plurality of shield plates can be reduced to the width of the recess of the opening, and the leakage of unwanted radiation can be reduced as compared with the conventional case.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a shield device according to an embodiment of the present invention.

In the figure, 1 is a chassis of a part of the shield case. A high-frequency circuit unit such as a television tuner (not shown) is mounted on the shield case. A twist tab 2 is provided on the chassis 1. The twist tab 2 has a thin base 2b so that the head 2a can be easily twisted.

A shield cover 3 is fitted on the chassis 1 so as to form a housing. However, because a high frequency circuit is mounted in the housing, the shield cover 3 is further shielded. The double shield structure is formed by stacking the covers 4.

In order to form this double shield structure, the shield cover (inner cover) 3 is made of a thin metal plate which is elastic in the stacking direction. A metal plate made of a thick and rigid material is used for the shield cover (outer cover) 4. The shield covers 3 and 4 are provided with slit-shaped openings 5 and 6 having a width that allows the head 2a of the twist tab 2 of the chassis 1 to penetrate therethrough. At the edge of the opening 5 of the shield cover 3, the base 2b of the twist tab 2 is provided.
The concave portion 5a is formed with a width that allows the fitting of In the case of this shield device, after the inner cover 3 and the outer cover 4 are superposed so that the opening positions thereof coincide with each other (arrow a), the twist tabs 2 of the chassis 1 are inserted into the respective openings 5 and 6, and then, As shown in FIG. 2, the inner cover 3 is slid with respect to the outer cover 4 in the direction of the arrow b, and the base portion 2b of the twist tab 2 is fitted into the recess 5a of the opening 5. As a result, the opening 6 of the outer cover 4 is partially blocked by the surface 3a of the inner cover 3 excluding the recess 5a. After that, FIG.
As shown in FIG. 4, the outer cover 4 is pressed by twisting the head portion 2a of the twist tab 2 in the direction of the arrow c, and the inner cover 3 is pressure-fixed to the chassis 1. At this time, since the inner cover 3 has elasticity, even if there are some irregularities on the upper surface of the chassis 1, the irregularities can be absorbed and adhered to obtain a good shielding effect.

As described above, according to the shield device of the present embodiment, the opening 6 of the outer cover 4 is slid on the inner cover 3 so that the surface 3a of the inner cover 3 allows the width W of the recess 5a to be reduced.
Since it is shielded up to 1, the width W1 after fixing can be almost halved as compared with the conventional case in the case of the twist tab 2 in which the width of the base portion 2b is about 1/2 the width of the head portion 2a. it can.

As a result, the leakage of unwanted radiation from the high frequency circuit can be reduced to half that of the conventional one.

[0020]

As described above, according to the shield device of the present invention, a recess is formed in the opening of one shield plate, another shield plate is stacked, and the shield plate having the recess is slid. Since the base of the twist tab is fitted in the recess, the width of the gap formed after fixing can be reduced to the width of the recess, and leakage of unnecessary radiation can be reduced as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a shield device according to an embodiment of the present invention.

FIG. 2 is a plan view showing when the inner cover 3 is slid in this shield device.

FIG. 3 is a view showing a gap S1 formed by twisting a twist tab 2 in this shield device.

FIG. 4 is a perspective view showing a conventional shield device.

FIG. 5 is a twist tab 50 in the conventional shield device.
It is a figure which shows the clearance gap S2 formed by twisting.

[Explanation of symbols]

1 ... Chassis, 2 ... Twist tab, 2a ... Head of twist tab 2, 2b ... Base of twist tab 2, 3 ... Inner cover, 4 ... Outer cover, 5, 6 ... Opening, 5a ... Opening 5 recessed part.

Claims (1)

[Claims] 1. A plurality of shield plates each having a slit-shaped opening are laminated so that the openings are aligned, a twist tab is inserted through these openings, and the tabs are twisted to form the shield plates. In a shield device integrally fixed to the shield plate, at least one opening of the shield plate is provided with a recess into which a base portion of the twist tab can be fitted, and the shield plate is attached to another shield plate. The shield device is characterized in that the base portion of the tab twist is fitted into the concave portion of the opening, and the twist tab is twisted.