JPH0536312Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention is designed to house various high-frequency circuit devices, to prevent the high-frequency circuit devices from radiating unnecessary high-frequency signals to the outside world, and to prevent unnecessary high-frequency signals from being emitted from the outside world. The present invention relates to a shield structure used to prevent high frequency noise from entering.

"Prior Art" Figure 2 shows a conventional shield structure. In the figure, numeral 1 indicates a shield case in which one side is an open opening, and this opening is closed with a cover plate 2. The cover plate 2 is generally a wiring board on which a high frequency circuit is mounted,
A shield case 1 is attached to the front and back sides of this wiring board to shield and protect the high frequency circuit device mounted on the wiring board.

The conventional shield case 1 has a concave groove 3 on the contact surface with the lid plate 2, and a conductive gasket 4 is placed in this concave groove 3.
The elasticity of the gasket 4 is used to prevent a gap from forming between the shield case 1 and the cover plate 2.

In other words, a common potential conductor is formed on the wiring board 2 constituting the cover plate 2 at a portion where the gasket 4 is in contact with the common potential conductor, and the gasket 4 is electrically contacted with this common potential conductor, so that the shield case 1 is electrically connected to the common potential conductor. Functions to connect to electric potential.

Long screws 5 are passed through the two shield cases 1, and by tightening the long screws 5, pressure is applied between the two shield cases 1 and the cover plate 2 is tightened.
sandwich. At this time, the gasket 4 is pressed against the cover plate 2 and elastically deforms, and is in close contact with the cover plate 2 without any gaps, creating a structure that prevents high-frequency signals from leaking out or entering from the outside through gaps. ing.

"Problem to be Solved by the Invention" In the conventional shield structure, the gasket 4 is fitted into the groove 3 formed in the edge surrounding the opening of the shield case 1. In other words, the wall thickness of the side plate of the shield case 1 must be selected to be large enough to form the groove 3.

Furthermore, since the groove 3 must be formed, it is generally manufactured by die casting.

The die-casting method requires molds and the like, which has the disadvantage of increasing manufacturing costs.

Further, in order to form the groove 3 for storing the gasket, the wall thickness of the side plate must be increased. This increases the weight of the shield case 1, which also has the drawback of increasing the weight of the entire device.

One way to make a box-shaped shield case at a low cost is to use sheet metal processing, but sheet metal processing cannot process a plate that is thick enough to form the groove 3 that accommodates the gasket 4. .

In addition, since it is difficult to achieve dimensional accuracy in sheet metal processing, unless the amount of elastic deformation of the gasket 4 is large, the lid plate 2
It also has the disadvantage of creating a gap between the two.

The purpose of this invention is to eliminate these disadvantages and provide a shield structure that can provide a reliable shielding effect using a plate-processed shield case.

``Means for Solving the Problems'' This invention consists of a box-shaped shield case made of a thin conductive plate and a string-like structure made of elastic conductive elastomer. A groove that engages along the edge of the open end of the shield case is formed along the edge of the opening end of the shield case, and a relatively shallow groove is formed on the bottom surface of the outside of the groove, and the surface on which this shallow groove is formed is By pressing against the lid plate that closes the opening surface of the shield case, the relatively shallow groove portion is crushed and elastically deformed. an elastic gasket that applies an elastic repulsion force to the shield case through this elastic deformation and absorbs unevenness on the edge of the shield case so that no gap is created between the shield case and the lid body;
This paper proposes a shield structure consisting of the following.

According to the structure of this invention, since the shield case is constructed from a thin conductive plate, the shield case can be made by sheet metal processing.

The gasket also has a groove that engages with the open end of the shield case, and this groove allows the gasket to be attached to the edge of the shield case.

Moreover, since a shallow groove is formed on the outer bottom surface of the gasket, when the shield case is brought into pressure contact with the lid plate, the groove is crushed and the gasket is elastically deformed. Due to this elastic deformation, the gasket generates a repulsive force between the lid plate and the shield case. Due to this repulsive force, the space between the shield case and the lid plate is sealed and the generation of a gap is prevented.

Therefore, even with a shield case made by sheet metal processing, there is no gap between the common potential conductor formed on the lid plate and the shield case, and it is possible to obtain the same shielding effect as a die-cast shield case. can.

As a result, this invention has the advantage of being able to construct a high-frequency device that is inexpensive and light in weight.

"Embodiment" FIG. 1 shows an embodiment of this invention. In the figure, 1 indicates a shield case, and 2 indicates a lid plate that closes the opening surface of this shield case 1. This cover plate 2 may be a wiring board or a conductive plate for shielding. This example shows a case where the lid plate 2 is a wiring board. High frequency circuits are formed on the front and back sides of the wiring board. For this reason, this example shows a case where the shield case 1 is attached to both the front and back sides of the lid plate 2.

In this invention, the shield case 1 is formed into a box shape by sheet metal processing from a relatively thin aluminum plate or the like having a thickness of, for example, about 1 mm. One side of the box is opened, and the lid plate 2 is placed over this open side to close the opening.

Attach the gasket 6 to the opening edge of the shield case 1. The gasket 6 is formed into a string shape from a conductive elastomer such as conductive rubber or conductive plastic. The cross section of this string-like gasket 6 is a deep groove 6.
A and a shallow groove 6B on the surface opposite to the surface on which the deep groove 6A is formed, and insert the edge of the side plate constituting the shield case 1 into the deep groove 6A, and open the opening of the shield case 1. Place the gasket 6 along the four circumferences of the Therefore, in this case, the string-like gasket 6 is cut to an appropriate size and engaged with the four circumferences of the opening of the shield case 1. In some cases, gasket 6
It is also possible to form the ring-shaped gasket 6 in advance into a ring shape, and to engage the ring-shaped gasket 6 with the four sides of the shield case 1.

The shield cases 1 arranged on both sides of the cover plate 2 are tightened with long screws 5 and pressed against the cover plate 2. At this time, the shallow groove 6 formed in the gasket 6
B is crushed by the pressing force from the shield case 1, and the entire bottom surface of the groove 6B is brought into contact with the cover plate 2.

When the groove 6B is crushed, a stroke is obtained in the depth direction of the groove 6B. Therefore, within this stroke range, even if the surface of the opening of the shield case 1 is slightly twisted, it is absorbed and the generation of a gap is prevented.

In addition, by crushing and elastically deforming the groove 6B, two fins 6C forming a deep groove 6A are formed.
A force can be applied to clamp the plates constituting the shield case 1. For this purpose gasket 6
Electrical contact between the shielding case 1 and the shielding case 1 is ensured, and a high shielding effect can be obtained in this respect as well.

"Modified Embodiment" In the above description, the shield case 1 is made by sheet metal processing, but if a large number of pieces are to be manufactured, die casting may be cheaper than sheet metal processing.

In such a case, a shield case formed by die casting may be used instead of sheet metal processing. When the shield case 1 is manufactured by a die-casting method, the thickness of the plate constituting the shield case 1 does not need to be very large.

In another example of the shield case 1, a box-shaped body is formed of a resin material, and a conductive plating layer is applied to the surface of the box-shaped body formed of the resin material by, for example, electroless plating. A shield case having a structure formed by adhesion can also be used.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of this invention, and FIG. 2 is a sectional view illustrating a conventional shield structure. 1...Shield case, 2...Lid plate, 5...Long screw, 6...Gasket, 6A...Deep groove, 6
B...Shallow groove.

Claims (1)

[Claims for Utility Model Registration] A. A box-shaped shield case made of a thin conductive plate with one side open; B. A string-shaped shield case made of an elastic conductive elastomer. A deep groove that engages with the edge of the opening end of the shield case is formed along the longitudinal direction, and a shallow groove is formed on the bottom surface outside the deep groove. By bringing the grooved surface into pressure contact with the lid plate that closes the opening surface of the shield case, the shallow groove portion is crushed to provide an elastic repulsion force to the shield case, and the shield case is A shield structure comprising: an elastic gasket that absorbs the unevenness of the edge so that no gap is created between the shield case and the lid;