JPH0625993Y2 - Shield case - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to, for example, a shield case for shielding a high frequency circuit.

[Prior Art] As a first conventional example of a shield case, there is one as shown in FIG. In the figure, 11 is a metal outer case, which is formed by mechanical cutting. On the other hand, the metallic lid 15 has side plates 15a formed by bending four sides, and an inner plate 16 is fixed to the inner surface by screws or the like. By mounting the inner plate 16, a groove 17 having a required width is formed on the inner portion of the side plate 15a over the entire circumference of the lid 15, and a flexible shield member 18 formed of a mesh wire or the like is formed in the groove 17. It is inserted. The shield member 18 is
The outer diameter of which is slightly larger than the depth of the groove 17 is used, and a part of the outer diameter is inserted into the groove 17 so as to protrude from the groove 17.

The lid 15 is attached to the outer case 11 in a state in which the shield member 18 is pressed against the end surface of the opening of the outer case, which is the contact surface 11a, to form a shield case.
The pressure-contacted shield member 18 has its cross-sectional shape deformed laterally due to its flexibility and is in close contact with the contact surface 11a.

In order to obtain a reliable shield effect in such a shield case structure, when the outer diameter of the shield member 18 is, for example, about 2 mm, the width of the contact surface 11a thereof is 2.6 mm.
The above is necessary. Therefore, the outer case 11 is formed to have a large wall thickness by the mechanical cutting process as described above so that the width of the contact surface 11a becomes equal to or larger than the above-mentioned required width. When the overall wall thickness is increased in this way, the outer case 11
Therefore, it is considered that only the portion of the contact surface 11a is left over the necessary width and the other portions are thinly formed, but such cutting is extremely difficult. Therefore, the first conventional example has a drawback that the weight cannot be reduced and the mounting space in the case is narrowed. There was also the problem of high costs.

On the other hand, FIG. 4 shows a second conventional example in which the weight is reduced.

In this conventional example, the outer case 12 is formed by bending and welding using a thin plate, and a lid fixing angle 14 is attached by spot welding at several points inside the opening. The lid 15 side is constructed in substantially the same manner as the first conventional example.

Then, the lid 15 is attached to the outer case 12 so that the shield member 18 is pressed against the end surface of the opening of the outer case 12 and the portion of the lid fixing angle 14 to form a shield case.

However, the lid fixing angle 14 has a curved surface when it is formed by bending. Therefore, even if the shield member 18 is to be pressed into contact with the end face of the opening of the outer case 12 and the portion of the lid fixing angle 14, the gap 19 is formed by the curved portion. If a gap 19 is formed on the contact surface, the shielding effect is deteriorated. Especially, when a high-gain amplifier / filter or the like having a high frequency (for example, in the order of GHz or more) is shielded, the gap 19 can reduce the signal. There has been a problem that electrical effects such as leaks and poor contact with the ground surface are large.

[Problems to be Solved by the Invention] In the first conventional example, since the outer case is formed to have a large wall thickness by mechanical cutting so that the width of the contact surface becomes a required width, the weight is reduced. However, there is a problem in that the mounting space inside the case becomes smaller. There was also the problem of high costs. In particular, in recent years, measuring instruments have been made smaller and lighter, and as easy as OA equipment has been demanded, and it has been necessary to meet such market demands.

On the other hand, the second conventional example, which is designed to reduce the weight, has a problem that the shield effect is deteriorated because a gap is formed on the contact surface of the shield member due to the curved surface of the lid fixing angle.

Therefore, an object of the present invention is to provide a shield case that can reduce the weight and cost while maintaining a reliable shield effect.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and includes a lid for holding a flexible shield member in a groove formed over the entire inner circumference, and an opening. A contact plate is fixed to the inside over the entire circumference, and an outer case in which a flat contact surface having a required width wider than the width of the shield member is formed by the opening end surface and the end surface of the contact plate, and the contact member. It is characterized by further comprising: a lid fixing angle that is fixed to the inside of the plate and fixes the lid to bring the shield member into close contact with the contact surface.

[Operation] A contact surface having a flat surface with a required width is formed by the end surface of the opening of the outer case and the end surface of the contact plate over the entire circumference of the opening of the outer case, and the contact surface is held over the entire inner circumference of the lid. The shield member is closely contacted to obtain a reliable shield and grounding effect.

The outer case has a contact plate having a required width secured to the opening portion so as to secure a contact surface with a required width, so that the outer case can be formed of a thin plate, and the weight and cost can be reduced.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

First, the structure of the shield case will be described. The outer case 1
Is formed into a required shape by bending and welding a metal plate having a plate thickness of about 1.6 mm. A contact plate 2 made of a metal flat plate having a plate thickness of about 1 mm is fixed by spot welding along the entire circumference inside the opening of the outer case 1. At this time, the end face of the outer case opening and the end face of the contact plate 2 are fixed so that their surfaces are aligned. However, there is no problem even if there is a step of about 0.2 mm. A contact surface 3 having a flat surface with a required width of about 2.6 mm is formed in the opening of the outer case 1 by the opening end surface of the outer case 1 itself and the end surface of the contact plate 2. Further, a lid fixing angle 4 is fixed by spot welding to the inside of the contact plate 2 over the entire circumference.

On the other hand, the portion of the lid 5 has substantially the same structure as that of the first and second conventional examples, and has a required width between the side end surface of the inner plate 6 and the inside of the side plate 5a which are attached by screwing. Groove 7 is formed. A flexible shield member 8 having an outer diameter of about 2 mm is fitted in the groove 7. As described above, the outer diameter of the shield member 8 is about 2 mm, while the width of the contact surface 3 is formed to about 2.6 mm, so that a sufficient width is secured for obtaining a reliable shield effect. The outer diameter of the shield member 8 is slightly larger than the depth of the groove 7, and part of the shield member 8 projects from the groove 7 when the shield member 8 is fitted in the groove 7.

The lid 5 is attached to the lid stop angle 4 and closed so that the shield member 8 is pressed against the contact surface 3 to form a shield case. The pressure-contacted shield member 8 is deformed in a laterally long cross-section due to its flexibility, so that it is in close contact with the contact surface 3 with certainty. In the shield case, on a wiring board (not shown), for example, 25d at 3GHz
An amplifier circuit having a gain of about B is incorporated and built in, and communicates with the outside through a coaxial connector or the like.

As described above, in the shield case of this embodiment, the contact surface 3 having a flat surface with a required width is formed over the entire circumference of the opening of the outer case 1 by the end surface of the opening of the outer case 1 and the end surface of the contact plate 2. The shield member 8 held around the entire inner circumference of the lid 5 is in close contact with the contact surface 3, and a reliable shield effect can be obtained even for a high-frequency amplifier having a high gain. Further, the outer case 1 can be formed of a thin plate because the contact plate 2 is applied to the opening portion to secure the contact surface 3 having a required width. Therefore, as compared with the conventional outer case manufactured by mechanical cutting, much weight reduction and cost reduction are realized.

[Effect of the Invention] As described above, according to the present invention, the contact surface having a flat surface with a required width is formed over the entire circumference of the opening of the outer case by the end surface of the opening of the outer case and the end surface of the contact plate. Since the flexible shield member held over the entire inner circumference of the lid is brought into close contact with this contact surface, the outer case can be formed of a thin plate and the mounting space can be maintained while maintaining a reliable shield effect. Is also secured, and there is an advantage that weight reduction and cost reduction can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a shield case according to the present invention in a state where a lid is opened, FIG. 2 is a longitudinal sectional view of a main part of the same embodiment, and FIG. 3 is a first conventional example of the shield case. And FIG. 4 is a partial vertical sectional view showing a second conventional example. 1 ... Outer case, 2 ... Contact plate, 3 ... Contact surface, 4 ... Lid stop angle, 5 ... Lid, 7 ... Groove, 8 ... Shield member.

Claims (1)

[Scope of utility model registration request] 1. A lid (5) for holding a flexible shield member (8) in a groove (7) formed along the entire inner circumference, and a cover (5) around the inner circumference of the opening. 2) is fixed, and an outer case (1) in which a flat contact surface that is wider than the width of the shield member by a required width is formed by the end surface of the opening and the end surface of the contact plate, and is fixed inside the contact plate. And a lid stopper angle (4) for bringing the shield member into close contact with the contact surface by fixing the lid.