JPH11186774A - Lnb shield structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-noise block LNB shield structure which is easily capable of improving the shield effect. SOLUTION: A primary radiator has a probe 5 for receiving radio waves incoming from a CS antenna, etc., into a waveguide 4 and a chassis 1 having an LNB circuit board 3, which amplifies signals from the probe 5 and transmits them from a connector 7 to a tuner, etc., shield cover 2 made of a conductive structure covers the outside of the LNB circuit board and fixes it to the chassis 1 of the primary radiator by screws 6 to electromagnetically seal the LNB circuit board 3 with a conductive cover 8 which has a shape conformed to a ground pattern 3a, disposed between the shield cover 2 and the ground pattern 3a of the LNB circuit board 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield structure of an LNB used for a primary radiator having a good electromagnetic shielding effect.

[0002]

2. Description of the Related Art FIG. 2 is a plan view (A) and a sectional side view (B) of a main part of a primary radiator showing a conventional LNB shield structure. A primary radiator chassis 1 for introducing radio waves from a CS antenna or the like into the waveguide 4 and receiving the signals with the probe 5 houses a first-stage amplifier and a frequency conversion circuit for amplifying the signal from the probe 5 with low noise. The mounted LNB circuit board 3 is mounted. The output from the LNB circuit board 3 is transmitted from the connector 7 to a tuner or the like. The outer periphery of the LNB circuit board 3 is
In order to prevent radio wave leakage, it is covered with a shield cover 2 made of a conductive structure such as aluminum, and screwed to the chassis 1 of the primary radiator with screws 6, 6,..., 26, 26,.
The LNB circuit board 3 is electromagnetically shielded. However, in such an LNB shield structure, the shield cover 2 is merely tightened with the screw 6 or the like.
A minute gap is formed between the B circuit board 3 and the shield cover 2, which causes radio wave leakage and characteristic deterioration.
Further, in order to improve the contact between the LNB circuit board 3 and the shield cover 2, a large number of screws 6, 6,.
It was necessary to conclude at 6, ...

[0003]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an LNB shield structure capable of easily improving a shield effect.

[0004]

Means for Solving the Problems An LNB (Low Noise Bloom) containing a first-stage amplifier and the like mounted on a chassis of a primary radiator is provided.
ck) In an LNB shield structure in which the outer periphery of the circuit board is covered with a shield cover made of a conductive structure and is screwed to the chassis to electromagnetically shield the same, between the shield cover and the ground pattern of the LNB circuit board. A conductive rubber having a shape corresponding to the ground pattern is provided.

A conductive rubber is provided between the chassis and the ground conductor surface of the LNB circuit board.

[0006] The thickness of the conductive rubber is approximately 0.5 mm.

[0007] The conductive rubber makes the central portion of the LNB circuit board thicker than the peripheral portion.

[0008] The conductive rubber is attached to a ground pattern of the LNB circuit board.

[0009] The conductive rubber is attached with a conductive adhesive.

[0010] The shield cover is screwed into the LNB.
The structure is performed only at the periphery of the circuit board.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an LNB according to the invention.
(A) plan view of a primary radiator main part showing the shield structure of FIG.
(B) The conductive rubber part top view, (C) LNB circuit board part top view, (D) side sectional drawing. Similar to the above conventional example,
A radio wave from a CS antenna or the like is introduced into the waveguide 4, and a signal from the probe 5 is amplified by the LNB circuit board 3 into the chassis 1 of the primary radiator which is received by the probe 5. To be transmitted. The outer periphery of the LNB circuit board 3 is covered with a shield cover 2 made of a conductive structure,
The screws 6 are screwed to the chassis 1 of the primary radiator to electromagnetically shield the LNB circuit board 3. Between the shield cover 2 and the ground pattern 3a of the LNB circuit board 3, a conductive rubber 8 having a shape conforming to the ground pattern 3a is provided.

The introduction of the conductive rubber 8 improves the close contact between the shield cover 2 and the ground pattern 3a of the LNB circuit board 3. Therefore, the screws 6, 6,... Peripheral part 3b of circuit board
It can be a structure that is performed only by using The conductive rubber can be a conductive rubber plate having a uniform thickness of about 0.5 mm, but by making the central portion 8a of the LNB circuit board 2 thicker than the peripheral portion 8b. The adhesion between the shield cover 2 and the ground pattern 3a of the LNB circuit board 3 can be made substantially uniform. The thickness of the conductive rubber was set to about 0.5 mm because if the thickness is too large, the shielding effect is reduced due to the impedance of the conductive rubber, and if the thickness is small, the adhesiveness is deteriorated. This is because the degree is empirically optimal.

The conductive rubber 8 is provided with a shield cover or L
By attaching the shield cover 2 to the chassis 1 by screwing the shield cover 2 to the chassis 1 in advance, the conductive rubber 8 can be easily positioned by attaching the conductive rubber 8 to the ground pattern 3a of the NB circuit board 3 in advance. The conductive rubber is provided not only between the ground pattern 3a of the LNB circuit board 3 and the shield cover 2 but also between the ground plane of the circuit board and the chassis to enhance the adhesion between the chassis and the ground plane, thereby preventing radio wave leakage and the like. Can be further improved.

[0014]

According to the present invention, the outer periphery of an LNB (Low Noise Block) circuit board containing a first-stage amplifier and the like mounted on the chassis of the primary radiator is covered with a shield cover made of a conductive structure, and is screwed to the chassis to electromagnetically. In the shield structure of the LNB to be shielded, by providing a conductive rubber having a shape corresponding to the ground pattern between the shield cover and the ground pattern of the LNB circuit board, the shielding effect can be easily improved. Problems such as leakage and performance degradation can be avoided, and the number of screws for screwing the shield cover to the chassis can be reduced, which is economical.

[Brief description of the drawings]

FIG. 1A is a plan view of an essential part of a primary radiator showing a shield structure of an LNB according to the present invention, FIG. 1B is a plan view of a conductive rubber part, FIG. FIG.

FIG. 2A is a plan view and FIG. 2B is a side sectional view of a primary radiator main part showing a conventional LNB shield structure.

[Explanation of symbols]

 Reference Signs List 1 chassis 2 shield cover 3 LNB circuit board 4 waveguide 5 probe 6 screw 7 connector 8 conductive rubber 9 conductive rubber 26 screw

Claims (7)

[Claims] 1. An outer periphery of an LNB (Low Noise Block) circuit board containing a first-stage amplifier and the like mounted on a chassis of a primary radiator is covered with a shield cover made of a conductive structure, and is screwed to the chassis for electromagnetically. A shield structure of an LNB, wherein a conductive rubber having a shape conforming to the ground pattern is provided between the shield cover and the ground pattern of the LNB circuit board. 2. The LNB shield structure according to claim 1, wherein a conductive rubber is provided between the chassis and a ground conductor surface of the LNB circuit board. 3. The thickness of the conductive rubber is approximately 0.5 mm.
The LNB shield structure according to claim 1, wherein: 4. The LNB shield structure according to claim 1, wherein the conductive rubber has a thickness at a central portion of the LNB circuit board larger than that at a peripheral portion. 5. The LNB shield structure according to claim 1, wherein said conductive rubber is attached to a ground pattern of an LNB circuit board. 6. The LNB shield structure according to claim 5, wherein the conductive rubber is attached with a conductive adhesive. 7. The method according to claim 7, wherein the shield cover is screwed onto the LN.
2. The LNB shield structure according to claim 1, wherein the structure is performed only at a peripheral portion of the B circuit board.