Small tuner unit having shielding effect

1. Field of the Invention

The present invention relates to a tuner unit for suitable use in a television.

2. Description of the Related Art

FIG. 3 is a perspective view showing the principal part of a known type of tuner unit whose cover is partially cut out, and FIG. 4 is a cross-sectional view of the principal part of the tuner unit.

The configuration of the tuner unit will be described below with reference to FIGS. 3 and 4 . A box-shaped frame 51 includes four metal side walls 52 , and upper and lower openings 51 a and 51 b.

A plurality of metal shielding plates 53 are provided in the frame 51 so as to partition the interior of the frame 51 into a plurality of compartments 54 . An input coaxial connector 55 and an output coaxial connector 56 are attached to one of the side walls 52 so that they are spaced from each other.

Chip components 58 , such as resistors and capacitors, are mounted on a wiring pattern (not shown) formed on the lower surface of a circuit board 57 , and electrical components 59 , such as coils, are mounted on the upper surface thereof while they are connected to the wiring pattern.

The circuit board 57 is also provided with a plurality of circuit blocks 60 , such as an input distribution circuit 60 a , an antenna tuning circuit 60 , an RF tuning circuit 60 c , a modulator circuit 60 d , and an RF output circuit 60 e.

The circuit board 57 is placed inside the frame 51 in a state in which a terminal 57 a protrudes outward from the frame 51 .

When the circuit board 57 is placed in the frame 51 , the shielding plates 53 standing upright on the circuit board 57 are positioned between the circuit blocks 60 including the input distribution circuit 60 a and the antenna tuning circuit 60 b . Thereby, the electrical components 59 are shielded from one another, and the circuit blocks 60 are electrically shielded from one another.

First and second covers 61 and 62 made of a metal plate include rectangular flat portions 61 a and 62 a , and retaining portions 61 b and 62 b bent from four edges of the flat portions 61 a and 62 a , respectively.

The first cover 61 is mounted so that the flat portion 61 a covers the opening 51 a and the retaining portions 61 b retain the side walls 52 . The second cover 62 is mounted so that the flat portion 62 a covers the opening 51 b and the retaining portions 62 b retain the side walls 52 .

Consequently, the interior of the frame 51 is shielded by the first and second covers 61 and 62 .

In the above-described known tuner unit, since the input distribution circuit 60 a and the antenna tuning circuit 60 b are separated by the shielding plate 53 standing upright on the circuit board 57 , the electrical components 59 must be mounted at a distance from the shielding plate 53 . Therefore, the circuit board 57 occupies a large area at that position, and the size thereof is increased.

Moreover, since a plurality of metal plates are used for the shielding plates 53 , the assembly efficiency is decreased, and the cost is increased.

Accordingly, it is an object of the present invention to provide a small and inexpensive tuner unit having a shielding effect.

In order to overcome the above problems, according to an aspect, the present invention provides a tuner unit including a box-shaped metal frame, and a circuit board placed inside the frame and having an electrical component mounted thereon, wherein a plurality of circuit blocks are formed on the circuit board, a metal shielding plate standing upright on the circuit board is provided between the circuit blocks so as to electrically shield the circuit blocks from each other, and a metal bridge that connects the shielding plate and the frame is provided between some of the circuit blocks and at a distance from the circuit board so that the electrical component can be mounted on a portion of the circuit board, the portion opposing the bridge.

This makes it possible to reduce the mounting space for the electrical component and to achieve a small tuner unit.

Moreover, the adjoining circuit blocks can be shielded from each other by the bridge.

Preferably, the electrical component is mounted on the portion of the circuit board. This makes it possible to reduce the mounting space for the electrical component and to achieve a small tuner unit.

Preferably, the bridge is placed between an input distribution circuit block and an antenna tuning circuit block among the circuit blocks. This can be suitably applied to, in particular, a case in which the adjoining circuit blocks do not need to be shielded completely.

Preferably, the frame, the shielding plate, and the bridge are made of a single metal plate. Therefore, the assembly efficiency is enhanced and the cost can be reduced.

Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiment with reference to the attached drawings.

FIG. 1 is a perspective view showing the principal part of a tuner unit of the present invention, whose cover is partially cut out;

FIG. 2 is a cross-sectional view of the principal part of the tuner unit;

FIG. 3 is a perspective view showing the principal part of a known tuner unit whose cover is partially cut out; and

FIG. 4 is a cross-sectional view of the principal part of the known tuner unit.

FIG. 1 is a perspective view showing the principal part of a tuner unit according to an embodiment of the present invention, whose cover is partially cut out, and FIG. 2 is a cross-sectional view of the principal part of the tuner unit.

The configuration of the tuner unit of this embodiment will be described below with reference to FIGS. 1 and 2 . A box-shaped frame 1 includes four metal side walls 2 , and upper and lower openings 1 a and 1 b.

A plurality of metal shielding plates 3 are provided in the frame 1 , and a bridge 4 is provided therein so as to connect one of the shielding plates 3 and one of the side walls 2 , thereby partitioning the interior of the frame 1 into a plurality of compartments 5 .

The frame 1 , the shielding plates 3 , and the bridge 4 are made of a single metal plate.

That is, as shown in FIG. 1 , the frame 1 is formed by bending a metal plate at connecting portions 2 a at the corners formed between the adjoining side walls 2 so that the side edges of the adjoining side walls 2 are aligned.

The shielding plates 3 are formed by bending a metal plate into the frame 1 at connecting portions 3 a each of which connects one side wall 2 and one shielding plate 3 , and connecting portions 3 b each of which connects two shielding plates 3 , thereby partitioning the interior of the frame 1 .

Furthermore, the bridge 4 is connected between the connecting portion 3 b of one shielding plate 3 and one side wall 2 . When the side wall 2 and the shielding plate 3 are bent, the bridge 4 is flush with the connecting portions 2 a , 3 a , and 3 b.

An input coaxial connector 6 a and an output coaxial connector 6 b are attached to one side wall 2 so that they are spaced from each other.

Chip components 8 , such as resistors and capacitors, are mounted on a wiring pattern (not shown) formed on the lower surface of a circuit board 7 , and electrical components 9 , such as coils, are mounted on the upper surface thereof while they are connected to the wiring pattern.

The circuit board 7 is also provided with a plurality of circuit blocks 10 such as an input distribution circuit 10 a , an antenna tuning circuit 10 b , an RF tuning circuit 10 c , a modulator circuit 10 d , and an RF output circuit 10 e.

The circuit board 7 is placed inside the frame 1 in a state in which a terminal 7 a protrudes outward from the frame 1 .

When the circuit board 7 is placed in the frame 1 , the input distribution circuit 10 a and the antenna tuning circuit 10 b of the circuit blocks 10 are placed in the compartments 5 adjoining with the bridge 4 therebetween, and the other circuit blocks 10 , such as the RF tuning circuit 10 c , the modulator circuit 10 d , and the RF output circuit 10 e , are placed in the compartments 5 defined by the shielding plates 3 .

In this case, the bridge 4 is disposed at a distance from the circuit board 7 . The electrical components 9 of the input distribution circuit 10 a and/or the antenna tuning circuit 10 b are placed on a portion of the circuit board 7 opposing the bridge 4 .

This makes it possible to reduce the mounting space for the electrical components 9 , and to reduce the size of the circuit board 7 .

First and second metal covers 11 and 12 include rectangular flat portions 11 a and 12 a , and retaining portions 11 b and 12 b bent from the four edges of the flat portions 11 a and 12 a , respectively.

The first cover 11 is mounted in a state in which the flat portion 11 a covers the opening 1 a and the retaining portions 11 b retain the side walls 2 , and the second cover is mounted in a state in which the flat portion 12 a covers the opening 1 b and the retaining portions 12 b retain the side walls 2 .

Consequently, the interior of the frame 1 is shielded by the first and second covers 11 and 12 . Moreover, since the flat portion 11 a of the first cover 11 is in contact with the bridge 4 , the effect of the bridge 4 of shielding the input distribution circuit 10 a and the antenna tuning circuit 10 b from each other can be enhanced.

While the present invention has been described with reference to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.