JPH0423523A - Satellite receiving tuner - Google Patents

Abstract

PURPOSE:To prevent a filter circuit and an amplifier circuit from being invaded by an external unnecessary element by arranging a circuit part for converting an input signal into a satellite 2nd intermedient frequency signal on a part corresponding to an input terminal in a 1st shield case, the filter circuit and the amplifier of which are covered with a 2nd shield case. CONSTITUTION:The input terminal 1 is fixed to the outside wall face of the 1st shield case 14 and other parts are arranged in the case 14. The 2nd shield case 15 is arranged in the case 14 in the vicinity of the input terminal 1 and the filter circuit 2 and the amplifier circuit 3 are covered with the case 15. Even when an unnecessary external signal in an 1GHZ band is invaded from the vicinity of the input terminal 1 into the case 14, the case 15 blocks the unnecessary signal. Thus, no external unnecessary signal is inputted to the filter circuit 2 and the amplifier circuit 3 in the circuit part.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a tuner for satellite reception.

2. Description of the Related Art A conventional satellite receiving tuner of this type has an input terminal mounted on the outer wall of a shield case, and transmits a satellite first intermediate frequency signal to a satellite second intermediate frequency signal to a portion inside the shield case corresponding to the input terminal. It had a circuit section that converted it into a signal.

Then, the 12CH2 signal received by the outdoor antenna is converted to IGH2, which is the satellite first intermediate frequency signal, by a converter, and applied to the input terminal via a cable, and is applied to the filter circuit and amplifier circuit in the circuit section. It was filtered and amplified.

Problems to be Solved by the Invention However, in such a conventional satellite receiving tuner, when another signal in the IGHZ band exists in free space, it enters the shield case from near the input terminal, As a result, there was interference with the regular IGH 2 band signal, which adversely affected subsequent signal processing.

Therefore, an object of the present invention is to prevent unnecessary signals from outside from entering the filter circuit and the amplifier circuit.

Means for Solving the Problems and in order to achieve this object, the present invention couples an input terminal of a satellite first intermediate frequency signal to the wall of a first shield case, and a first shield corresponding to this input terminal. A circuit section for converting to a satellite second intermediate frequency signal is provided in the inner part of the case, and a filter circuit for filtering the satellite first intermediate frequency signal and an amplification circuit for the satellite first intermediate frequency signal of the circuit section are covered with a shielding case. It is something.

If the configuration is as described above, even if an unnecessary signal in the IGH7 band from an external source enters the first shield case from near the input terminal, the second shield case will block the unnecessary signal, so the conclusion is that This prevents unnecessary signals from outside from entering the filter circuit and amplifier circuit of the circuit section.

EXAMPLE An example of the present invention will be described below with reference to the accompanying drawings. Figure 2 shows an electrical block diagram of a satellite reception tuner that is commonly used.
is a filter circuit, 3 to 5 are amplifier circuits, 6 is a mixer, 7
．． 8 is a filter circuit, 9 is an FM demodulation circuit, 10 is a threshold extension circuit, 11 is an oscillation circuit, 12
is a frequency divider, and 13 is a phased lock loop. Among these, the input terminal 1 is attached to the outer wall surface of the first shield case 14 shown in FIG. 1, and the other terminals are provided inside the first shield case 14.

Further, a second shield case 15 is provided near the input terminal 1 within the first shield case 14.
A shield case 15 specifically covers the filter circuit 2 and amplifier circuit 3 shown in FIG.

The second shield case 15 has a box shape with an open bottom, and the lower part of the side wall on the input terminal 1 side is cut out to accommodate the input terminal l.

Therefore, unnecessary external signals are likely to enter through this notch, so in order to compensate for this, the upper end of the side wall 14a of the first shield case 14 on the input terminal 1 side is bent toward the second shield case 15. A portion 14b is formed, which allows the first and second shield cases 14.1 to be separated as much as possible.
The interval between 5 is narrowed.

Further, since the portion 15a of the second shield case 15 facing the input terminal 1 protrudes toward the input terminal 1 side as shown in FIG. There is.

In other words, the second shield case 15 can now be easily attached or detached from above.

If the configuration exceeds the effects of the invention, even if an unnecessary signal from an external source enters the first shield case from near the input terminal, the second shield case prevents the unnecessary signal from entering the inside thereof. Therefore, the conclusion is that unnecessary signals from outside will not enter the circuit section.

[Brief explanation of drawings]

FIG. 1(a) is a top view of a satellite reception tuner according to an embodiment of the present invention, FIG. 1(b) is a cross-sectional view taken along line bb' of FIG. 1(a), and FIG. 2 is a circuit block thereof. It is a diagram. 1... Input terminal, 2... Filter circuit, 3... Amplifier circuit, 14... First shield case, 15... Second shield case.

Claims (1)

[Claims] An input terminal for the satellite first intermediate frequency signal is coupled to the outer wall surface of the first shield case, and a circuit section for converting the satellite to the second intermediate frequency signal is provided in the inner part of the first shield case corresponding to the input terminal, A tuner for satellite reception in which a filter circuit for filtering a satellite first intermediate frequency signal and an amplification circuit for the satellite first intermediate frequency signal among the circuit portion are covered with a second shield case.