JPH01125897A - Device for shielding high frequency circuit - Google Patents

Abstract

PURPOSE:To enable a shielding device to be miniaturized and facilitate the assembly of it by a method wherein an earth pattern of a conductor foil is formed on a main substrate and the earth pattern is made to serve also as a part of a shielding case. CONSTITUTION:An earth pattern 8 of a conductor foil is formed on a main substrate 1, and the pattern 8 is made to serve also as a part of a shielding case 2. That is, a circuit element constituting a high frequency circuit and a sub-substrate provided with a printed circuit are made to be shielded in all and upward directions by shielding plates 3, 6, and 7 and also shielded in a downward direction by an earth pattern 8 provided to the main substrate 1. Therefore, the earth pattern is made to serve also as a shielding plate. By these processes, a shielding plate for the main substrate 1 and the sub-strate 5 can be dispensed with, so that the space between the main substrate 1 and the sub-substrate 5 can be reduced to half, and not only a device of this design can be miniaturized in an outer shape dimension but also a structure used for mounting a shielding plate can be dispensed with and an assemling man-hour can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shielding device for high frequency circuits that require shielding, such as television tuner circuits and RF modulator circuits.

[Prior Art] Conventionally, when shielding a high frequency circuit, as shown in Figure 3, each circuit that requires shielding is divided on the main board (1), and the left and right shield plates of the shield case (2) are separated. (3) Plant this shield plate (3) (3)
A sub-board (5) having a high-frequency circuit element (4) is fixed approximately in the height direction of the sub-board (5), and shield plates (6) (7) are further placed to cover the top and bottom surfaces of this sub-board (5). It was set up.

Problem to be solved by invention C 1 In the above shield structure, the left and right shield plates (3) (3) of the shield case (2), the upper shield plate (6)
, it is necessary to assemble a shield plate (7) between the sub-board (5) and the main board (1) and a number of shield plates to form an independent shield case (2) that completely surrounds the high-frequency circuit. there were. In this way, since it is necessary to make an independent shield case (2) for each block, there are problems such as not only the assembly is troublesome but also the external dimensions become large.

[Means for Solving the Problems] The present invention has been made to solve the above problems.
A shielding device for a high frequency circuit that is installed on a main board while being shielded by a shield case, in which a ground pattern of conductive foil is formed on the main board, and this ground pattern portion is also used as a part of the shield case. It is.

[Operations] The front, rear, left, right, and top surfaces of the sub-board on which the circuit elements and printed wiring that make up the high-frequency circuit are installed are shielded by shield plates, and the bottom surface is shielded by the ground pattern formed on the main board.

Therefore, the ground pattern also serves as a shield plate.

[Embodiment] An embodiment of the present invention will be described based on FIGS. 1 and 2.

In FIG. 1, (1) is a main board, and the entire surface of the main board (1) corresponding to a high frequency circuit that requires shielding is a ground pattern (8) made of conductive foil. The main board (1) further has mounting holes (9) for fixing the upright shield plate (3) by soldering.
), and the legs (10) of the shield plate (3) are inserted into these mounting holes (9) and soldered. Further, a sub-board (5) is fixed to the substantially middle part of the shield plate (3) in the height direction, and a high-frequency circuit element (4) is fixed to this sub-board (5).
) are connected. On the upper surface of the shield plate (3) is a shield case (2) as shown in Figures 1 and 2.
A shield plate (6) that can be completely covered and shields the upper surface is removably fitted.

[Effects of the Invention] Since the present invention is configured as described above, the shield plates for the main board and the sub-board are not required, the distance between the peripheral boards can be reduced by about half, and the external dimensions can be reduced.

Furthermore, no structure is required for attaching the shield plate, and the number of assembly steps can be reduced. Furthermore, on the main board that has a ground pattern, there is an interstage double tuning circuit.

Even if a microstrip line as a resonant inductor for a local oscillation circuit, a high frequency filter circuit, etc. is formed in a pattern, the main board also serves as a shield plate, and a separate shield plate is not required.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the shielding device according to the present invention, FIG. 2 is an exploded perspective view of the same, and FIG. 3 is a sectional view showing a conventional example. (1)... Main board, (2)... Shield case, (3) (6) (7)... Shield plate, (4)...
-Circuit element, (5)...Sub board, (8)...Earth pattern, (9)...Mounting hole, (10)...Legs. Applicant Fujitsu General Yamaha Ltd.-□ 1 Agent Patent attorney Toshiaki Furusawa □;. ---Same Patent Attorney Kano -M □ Figure 4 Figure D'/7 Figure 2

Claims (1)

[Claims] (1) In a high-frequency circuit shielding device in which a sub-board that constitutes a high-frequency circuit that requires shielding is installed on a main board while being shielded by a shield case, a ground pattern of conductive foil is formed on the main board, and this A shielding device for a high frequency circuit, characterized in that a ground pattern portion also serves as a part of the shielding case.