JPH0238015B2 - CHUUNA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tuner for a TV receiver that receives a TV signal, selects a desired TV channel, and converts the frequency to an intermediate frequency. This relates to a tuner using a super-heterodyne system (hereinafter referred to as a double-super system).

Configuration of conventional example and its problems Figure 1 is an exploded perspective view of the housing of a conventional double super type tuner. They are separated by a plurality of shield plates 2 placed parallel to or perpendicular to the frame. Note that 3 and 4 are the upper and lower lids of the housing 1. Now, especially in the double super method, the two existing mixer parts, that is, the board before the first mixer part and the board after the second mixer part, are separated,
A method is often adopted in which a space 5 is provided between them, and each is surrounded by shield plates 2a and 2b.

In this case, if the shielding effect is prioritized, a large number of shield plates will be required, and a surrounding ground pattern will need to be secured, and the area will become large because the boards are all arranged on almost the same plane, making it unsuitable for miniaturization. . Furthermore, especially when a shielded space is provided between the first mixer section and the second mixer section, the volume increases by the space. Furthermore, due to the complex structure,
High manufacturing costs also pose a problem.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems and provides a tuner that is suitable for miniaturization, has good shielding effect and temperature characteristics, and is easy to manufacture.

Structure of the Invention The present invention provides a printed circuit board including a microstrip circuit of a first mixer section including a first local oscillation section, and a microstrip circuit of a second mixer section including a second local oscillation section. A printed circuit board consisting of a lip circuit is separated, one side of each of the two printed circuit boards is a ground surface, each of the ground surfaces is bonded to the bottom surface of the case chassis of a different part, and the ground surface side of the two printed circuit boards is The housing portions are placed back to back to form a double structure, and adjacent to one side of the double structure,
A storage part is provided for storing a filtering means having a first intermediate frequency bandpass filter, and the first mixer part and the second mixer part are connected, and the first mixer part housing and the second mixer part are connected to each other. The case of the input circuit section consists of two side surfaces adjacent to both the mixer section case and the storage section, one of which is a mounted circuit board that includes a broadband high frequency amplifier, and the other side that includes a mounted circuit board that includes a second intermediate frequency amplifier. The above object is achieved by providing a casing for the output circuit section consisting of the following.

DESCRIPTION OF EMBODIMENTS The present invention will be described below along with one embodiment thereof using the drawings. FIG. 2 shows a circuit diagram of a tuner according to an embodiment of the present invention, in which a signal sent from an input circuit section 6 including a wideband high-frequency amplifier is transmitted to a first oscillator whose oscillation frequency can be set by a voltage-controlled oscillator. A mixer section 7 including a local oscillation section converts the frequency into a first intermediate frequency. Then, the output is waved by a first intermediate frequency band pass filter 8, and further, the signal is converted to a second intermediate frequency by a mixer section 9 including a second local oscillation section, and then an output including a second intermediate frequency amplifier. The circuit configuration is such that the signal is output via the circuit section 10.

Next, the tuner having the above configuration will be explained together with its housing.

FIG. 3 shows the external appearance of a tuner according to an embodiment of the present invention, FIG. 3 a is a plan view thereof, FIG. 3 b is a side sectional view taken along dotted line A, and FIG. 3 c is a side sectional view taken along dotted line B. It is. In the tuner shown in FIG. 3, one surface of the substrate 11 and substrate 12, which are composed of microstrip circuits, ie, the surfaces facing each other, are grounded. The ground planes of the substrates 11 and 12 are placed back to back with a chassis 13 or 14 in between to form a microstrip circuit. Note that the chassis 14 is not necessarily required, and the chassis 13 may also serve as the chassis 14. The substrates 11 and 12 are surrounded by rectangular housing frames 15 and 16. A mixer including a first local oscillator of a double super tuner is provided in a housing interior 17 made of the chassis 13 and the housing frame 15 and a housing interior 18 made of the chassis 14 and the housing frame 16. A mixer section 9 including a section 7 and a second local oscillation section is housed therein. Note that the housing frames 15 and 16 may be separated or connected. The same applies to the chassis 13 and the housing frame 15 or the chassis 14 and the housing frame 16. and housing frames 15 and 1
A housing part 19 for the first intermediate frequency bandpass filter 8 is provided adjacent to the side surface of the filter 6, and a signal is inputted from the inside of the housing 17 or the inside of the housing 18 and output to the inside of the housing 18 or the inside of the housing 17. . With the housing interiors 17 and 18 and the filter housing section 19,
Also, although forming one housing block, there are two side faces that are adjacent to all three of the side faces. An input section casing 20 is connected to one side of the side, and an output section casing 21 is connected to the other side. Note that the frame width of the input unit housing 20, the total width of the housing frames 15 and 16,
If the frame width of the filter accommodating part 19 and the frame width of the output part housing 21 are made the same, the lid 3, as shown in FIG.
Convenient when doing 4. Overall, the 4th
As shown in the figure, a part of the center has a double structure.

By adopting such a configuration, the input section 20 where the input circuit section 6 is provided, the inside of the casing 17 where the mixer section 7 is provided, the inside of the casing 18 where the mixer section 9 is provided, and the output circuit section 10 are separated. The output section 21 provided is all on a separate board, but inside the casing 1
Since the boards mounted on 7 and 18, that is, the boards 11 and 12, are composed of microstrip circuits, the input part board 22 or the output part board 23
should originally be a separate board. In addition, when lids 3 and 4 are provided, the distance between the lid and the board and mounted circuit components is approximately half that of the other parts, but the distance between the lid and the board and mounted circuit components is approximately half that of the other parts. This is not a problem since it can be implemented in Furthermore, a first mixer section 7 including a first local oscillation section,
The mixer section 9 including the second local oscillation section is placed inside the housing 1.
7 and the interior of the casing 18, the casing provides shielding, and the casing is inevitably separated into sections that should be shielded. Further, the substrates 22 and 23 in the input section 20 and the output section 21 are separate substrates from the substrates 11 and 12 made of microstrip circuits, and do not have a double structure, so the substrates 11 and 12 are It is possible to use the solder dip method before installing the wafer, reducing manufacturing costs. Further, since the mixer sections 7 and 9 are completely separated from the input circuit section 6 and the output circuit section 10 having large amplifiers, their temperature characteristics are good.

Effects of the Invention As explained above, the present invention has a microstrip circuit configuration in which the first mixer section and the second mixer section have a double structure back to back, and the double structure is connected to the side surfaces of the first mixer section and the second mixer section. Since the wave means having the first intermediate frequency bandpass filter is mounted in the casing, it is possible to achieve miniaturization, and the double-structure housing chassis allows for the first mixer section and the necessary A sufficient shielding effect with the second mixer section can be obtained. In addition, since the input circuit section and the output circuit section are provided on both sides with the high frequency part in between, the structure is advantageous in terms of input/output isolation characteristics and shielding effect. There is. Furthermore, according to the structure of the present invention, the solder dip method is possible, and the manufacturing cost can be reduced.
The second mixer section includes an input circuit section having a large amplifier;
Since it is completely separated from the output circuit section and both are provided in the same housing, the temperature characteristics are good.

[Brief explanation of drawings]

Figure 1 is an external view of the conventional tuner casing, Figure 2
The figures are a circuit diagram of a tuner according to an embodiment of the present invention, FIG. 3a is a plan view of the tuner, FIGS. 3b and c are side sectional views of the tuner, and FIG. 4 is an external view of the tuner. It is. 6... Input circuit section, 7... Mixer section, 8... First intermediate frequency band pass filter, 9... Mixer section, 10... Output circuit section, 11, 12... Microstrip circuit board, 13 , 14... Ground surface chassis, 15, 16... Base housing frame chassis, 1
7, 18... Inside the housing, 19... First intermediate frequency band pass filter housing section, 20... Input section, 21
...Output section, 22, 23... Board.

Claims (1)

[Claims] 1 of the first mixer section including the first local oscillation section,
A printed circuit board consisting of a microstrip circuit, and a second mixer section including a second local oscillation section.
A printed circuit board consisting of a microstrip circuit is separated, one side of each of the two printed circuit boards is a ground surface, each of the ground surfaces is bonded to the bottom surface of the case chassis of a different part, and the ground surfaces of the two boards are connected to each other. The first,
A storage section for accommodating a filtering means on a board separate from the printed circuit board of the second mixer section is provided, the first mixer section and the second mixer section are connected, and the first mixer section housing is connected to the second mixer section. , a mounted circuit on a board separate from the printed circuit boards of the first and second mixer sections, including a broadband high-frequency amplifier on one of two side surfaces adjacent to both the second mixer section housing and the storage section. A casing of the input circuit section is made of a substrate, and a casing of the output circuit section is provided with a casing of a mounted circuit board that is a separate board from the printed circuit boards of the first and second mixer sections and includes a second intermediate frequency amplifier on the other side. Chiyuna is characterized by that.