JPH0218627Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a modulator, and its purpose is to create a structure in which the modulator part and other high-frequency circuit parts are integrated, and to create a connection between the modulator part and other high-frequency circuit parts. The purpose is to prevent signal leakage from the modulator section to other high frequency circuit sections by interposing a plurality of shield plates.

Generally, as shown in Fig. 1, an RF modulator A is used to convert a video signal reproduced by a video tape recorder or the like into a signal that can be received by a television receiver, and an RF modulator A is used to switch between signals from a television antenna C. Connected to the high frequency switch or antenna mixer B using a coaxial cable, etc.
By changing the switch B, the television receiver receives a signal from a general broadcasting station or a video tape recorder.

In the figure, _A1 is the input terminal from the video tape recorder, _A2 is the output terminal to the high frequency switch or antenna mixer B, _B1 is the input terminal from antenna C, and _B3 is the input terminal from modulator A. The input terminal, _B3 , is the output terminal to the television receiver. _B4 is the output terminal to the tuner of the video tape recorder.

By the way, in the case of the conventional example described above, the modulator A and the other high frequency circuit section B (high frequency switch or antenna mixer) are provided in separate chassis, which not only complicates their handling but also makes it difficult to install the set (video tape recorder). However, there are disadvantages such as the need for a large installation space for a television receiver), and in recent years, both have been housed adjacently in one chassis. However, in this case, it is common to install one shield plate between the two, so simply one shield plate does not have much shielding effect, especially when the frequency of the RF modulator is in the VHF band. Above, i.e.
In the UHF band, there were drawbacks such as an increase in the amount of current leaking to the outer surface of the chassis, making it impossible to obtain a satisfactory shielding effect.

The present invention has been devised in view of the above points, and eliminates the above drawbacks by adopting the structure described below.

That is, one embodiment of the present invention will be described in detail with reference to FIGS. 2 to 5. 1 is a chassis, and the chassis 1 is formed into a box shape by cutting, bending, or other press processing from a single metal plate. The formation method will be described in detail using the developed view of FIG.
2 is a right side plate, 3 is a left side plate, and the left and right side plates 2 and 3 have mounting holes 3a for an input terminal 22 for receiving an input signal from an antenna, and an output terminal 21 for outputting an output signal to the television. 2a is provided. Further, the left and right side plates 2 and 3 have protrusions 2b, 2b, 3b, 3b for positioning the printed circuit board 11 of the modulator section A, and for positioning the printed circuit board 18 of another high frequency circuit section B, for example, an antenna mixer. protrusions 2c, 2c,
3c and 3c are provided. Reference numeral 4 denotes a front side plate, and the side plate 4 is provided with a rectangular hole 4a for allowing the printed circuit board 11 to protrude. 5 is a rear side plate, and the rear side plate 5 is provided with a mounting hole 5a for an output terminal 23 for outputting an output signal to a video tape recorder.

By bending these left, right, front, and rear side panels 2 to 5 downward from their bases, a box shape is formed, as is clear from the figure.
The top and bottom surfaces are open. That is, the chassis 1 is generally constituted by the side plates 2 to 5. Reference numeral 6 denotes a first shield plate provided at one open end, and the shield plate 6 has protruding holes 6a, 6a formed by burring, as is clear from FIG.
are provided, and protruding pieces 6b, 6 are provided on both sides.
b is provided. Reference numeral 7 designates a second shield plate, and the second shield plate 7 is provided with holes 7a, 7a, and projecting pieces 7b, 7b are provided on both sides. The first and second shield plates 6,
A portion of 7 is connected to the left and right side plates 2 and 3 via a bridging member. 8 is a rectangular hole for dividing the shield plates 6 and 7. The first and second shield plates 6 and 7 are shown in FIG.
It is bent downward into a U-shaped cross section so that the two face each other with the line and the Y-Y line as boundaries.
At this time, the protrusion hole 6 provided in the first shield plate 6
a, 6a are holes 7a provided in the second shield plate 7,
Opposite 7a. FIG. 4 shows the side panels 2 to 5 and the shield plates 6, 7, which are bent at predetermined positions. As is clear from the figure, two storage areas 9 and 10 are formed in the chassis 1, separated by shield plates 6 and 7. In the storage section 9, there is a modulator section A, and
The housing section 10 houses another high frequency circuit section B, such as an antenna mixer or a high frequency switch, and in this embodiment, the antenna mixer is housed therein. The modulator section A includes an oscillator 12, a variable resistor 13, a modulation IC 14, transistors 15, 15,
Main electrical components such as resistors 16, 16 and a coil 17 are attached to the structure. When the printed circuit board 11 is stored in the storage section 9, a portion 11a
protrudes from a rectangular hole 4a provided in the front side plate 4, and protrusions 2b, 2 provided in the left and right side plates 2, 3.
b, 3b, 3b. The antenna mixer section B consists of main electrical components such as coils 19..., transistors 20..., resistors 26..., and capacitors (not shown) mounted on a printed circuit board 18, and receives signals from the TV antenna and the modulator section A. It mixes the signals from the Note that the printed circuit board 18 is located in the storage section 10.
When stored in the housing, it is positioned by the protrusions 2c, 2c, 3c, and 3c provided on the left and right side plates 2 and 3.
22 is an input terminal provided on the left side plate 3, 21 is an output terminal provided on the right side plate 2, and the terminal portions of both terminals 22, 21 are connected to the printed circuit board 18. 2
4 and 25 are feedthrough capacitors that are penetrated into protruding holes 6a, 6a provided in the first shield plate 6 and holes 7a, 7a provided in the second shield plate 7;
The feedthrough capacitors 24 and 25 electrically connect the modulator section A and the antenna mixer section B. At this time, feedthrough capacitors 24, 25
are the protruding holes 6a and 6 between the shield plates 6 and 7.
Since it is covered by a, feedthrough capacitor 2
Leakage of signals from 4 and 25 can be prevented. Also,
Since it is installed in the protruding holes 6a, 6a, the installation is also easy. A connector and a power terminal for inputting a video signal from a video tape recorder are attached to a portion 11a of the printed circuit board 11 that protrudes outward from the chassis 1. After storing the modulator part A and the antenna mixer part B in the storage parts 9 and 10 of the chassis 1, a cover 2 is attached to the open end of both parts as shown in FIG.
Assembly is completed by attaching 7....

As mentioned above, the present invention is a system in which a modulator section A and another high frequency circuit section B (antenna mixer, high frequency switch) are housed adjacent to each other in the same chassis 1. A bridging member is formed integrally with the chassis in between, and both ends of the bridging member are bent to interpose a plurality of opposing shield plates 6 and 7 having a U-shaped cross section, and substrates are placed in opposing portions of the shield plates. Since the configuration is such that no signal is disposed, leakage of signals from the modulator section to other high frequency circuit sections can be prevented, and effects such as high performance can be achieved without interference between signals from the television antenna and signals from the modulator.

Further, if the shield plate is formed integrally with the chassis as in the above embodiment, manufacturing is simple and suitable for mass production.

Furthermore, by making a protruding hole in the shield plate by burring and installing a feedthrough capacitor in the protrusion hole, it is possible to prevent signal leakage from the feedthrough capacitor, which not only provides higher performance but also makes it easier to install. be.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional example, Figs. 2 to 5 show an embodiment of the present invention, Fig. 2 is an exploded view of the chassis 1, Fig. 3 is a sectional side view thereof, and Fig. 4 is a plan view. FIG. 5 is a side view. A... Modulator section, B... High frequency circuit section (antenna mixer), 1... Chassis, 6, 7...
...Shield plate, 11...Modulator section printed circuit board, 18...High frequency circuit section (antenna mixer) printed circuit board.

Claims (1)

[Scope of utility model registration request] In a case where the substrates constituting the modulator section and another high-frequency circuit section are housed adjacently in the same chassis, a bridging member that partitions the modulator section and the other high-frequency circuit section is formed integrally with the chassis. A modulator characterized in that both ends of the bridging member are bent to form a plurality of opposing shield plates each having a U-shaped cross section, and no substrate is disposed at the opposing portions of the plurality of shield plates.