JP2594746Y2 - Shield device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield device for shielding an electric circuit mounted on a printed circuit board, and more particularly to a shield device for reducing the number of parts and reducing the thickness.

[0002]

2. Description of the Related Art A conventional shield device is shown in FIG. In the drawing, reference numeral 1 denotes a printed board, and 2 denotes an electric component mounted on the printed board, for example, a resistor, a transistor, and the like. Reference numerals 3 and 4 denote shield cases which surround the plurality of electric components 2 so as to sandwich the printed circuit board 1 and are fixed with screws to shield an electric circuit constituted by the electric components 2.

[0003]

[Problems to be Solved by the Invention] In such a configuration, there are the following problems. In order to perform shielding, a certain distance is required above and below the printed circuit board 1. When a large number of printed circuit boards 1 are inserted into slots, the distance between adjacent boards cannot be reduced. turn into. Also, if the shield case is 2
And the number of parts is increased.

[0004] An object of the present invention is to realize a shield device that can reduce the number of parts and reduce the thickness.

[0005]

According to the present invention, there is provided a shield device for shielding an electric circuit mounted on a printed circuit board, wherein a shield case for covering the electric circuit and one of the electric circuit provided on the printed circuit board are provided. A circuit pattern that constitutes a portion, an electrical layer that is electrically connected to the electric circuit, and an electrical layer that is electrically connected to the shield case, and is provided below the circuit pattern on a lower layer of the printed circuit board; And a shield layer provided in a lower layer of the printed circuit board from the ground layer and surrounding the electric circuit together with the shield case for shielding.

[0006]

According to the present invention, the electric circuit is surrounded and shielded by the shield case and the shield layer provided on the printed circuit board.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure,
5 is a printed circuit board; 61 and 62 are electric components provided on the printed circuit board 5; 7 is a shield case;
2 to cover the electric circuit. Next, the configuration of the printed circuit board 5 is shown in FIG. In the figure, reference numeral 51 denotes a circuit pattern for connecting electric components 61 and 62 in an electric circuit. Reference numeral 52 denotes an earth layer, which is electrically connected to an electric circuit and is provided in a lower layer than the circuit pattern 51.
Reference numeral 53 denotes a shield layer, which is electrically connected to the ground layer 52 and is provided below the ground layer 52, and surrounds and shields the electric component 6 of the electric circuit together with the shield case 7.

[0008] Further, ● represents a circuit pattern 51 and a ground layer 5.
2, holes that can be connected to the shield layer 53, and ○ indicates holes that cannot be connected. Next, the details will be described. The holes 51a, 52a,
The holes 53a and 53a are electrically connected to the ground layer 52 and the shield layer 53, respectively.
Holes 51b into which electric components 61 are inserted are holes 52b and 53b.
The hole 52 b can be electrically connected to the ground layer 52. The hole 53b cannot be electrically connected to the shield layer 53. The hole 51c into which the electric component 61 is inserted can be electrically connected to the circuit pattern 51, and is connected to the holes 52c and 53c.
2. It cannot be electrically connected to the shield layer 53. The hole 51d into which the electric component 62 is inserted can be electrically connected to the circuit pattern 51, and is connected to the holes 52d and 53d.
2d and 53d are an earth layer 52 and a shield layer 53, respectively.
Cannot be electrically connected to The hole 51e into which the electric component 62 is inserted can be electrically connected to the circuit pattern 51, and the hole 52e
e, 53e, and the holes 52e, 53e cannot be electrically connected to the ground layer 52 and the shield layer 53, respectively.

The operation of such a device is described below.
The electric components 61 and 62 are mounted on the printed circuit board 5. Then, the leg portion 71 of the shield case 7 is inserted into the hole 51a, and is attached to the printed circuit board 5 by soldering. As a result, the electric component 6 is formed by the shield case 7 and the shield layer 53.
1, 62 can surround the electric circuit constituted by
Can shield.

Next, the operation of the return current will be described. FIG.
FIG. 2 is an explanatory diagram of the operation of the apparatus of FIG. When the low-frequency return current is output from the electric component 61, it passes through the paths A, B, and C. That is, it flows through the ground layer 52 via the electrically connectable hole 52b, flows through the shield case 7 via the electrically connectable hole 52a, and flows through the shield layer 53 via the electrically connectable hole 53a. However, since the high-frequency current flows through the shortest path, the high-frequency return current passes through path A. That is, the earth layer 52 flows, but the shield case 7 and the shield layer 53 do not flow. As a result, the high-frequency return current passes through a path surrounded by the shield case 7 and the shield layer 53.
A high-frequency return current that is easily affected by disturbance can be shielded.

[0011]

According to the present invention, the following effects are obtained.
Since the electric circuit is shielded by the shield case and the shield layer, the number of parts of the shield device can be reduced and the thickness can be reduced. Since the high-frequency return current passes through the path of the earth layer surrounded by the shield case and the shield layer, the high-frequency return current that is easily affected by disturbance can also be shielded.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a printed circuit board 5 of the apparatus of FIG.

FIG. 3 is an operation explanatory diagram of the device of FIG. 1;

FIG. 4 is a configuration diagram showing a conventional shield device.

[Explanation of symbols]

 Reference Signs List 5 printed circuit board 61, 62 electric component 7 shield case 51 circuit pattern 52 ground layer 53 shield layer

Claims (1)

(57) [Scope of request for utility model registration] 1. A shield device for shielding an electric circuit mounted on a printed circuit board, a shield case covering the electric circuit, a circuit pattern provided on the printed circuit board and constituting a part of the electric circuit, Electrically connected to the electric circuit and the shield;
An earth layer electrically connected to a case and provided on a lower layer of the printed circuit board from a circuit pattern ; and an electrically connected ground layer and provided on a lower layer of the printed circuit board from an earth layer and the shield case. And a shield layer which surrounds and shields the electric circuit.