JP3956761B2 - Signal receiving apparatus and signal receiving circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal receiving device and a signal receiving circuit, and in particular, a signal for receiving at least one broadcast wave by a plurality of receiving circuits, or receiving a plurality of broadcast waves by individual receiving circuits corresponding thereto. The present invention relates to a receiving device and a signal receiving circuit suitable for the signal receiving device.
[0002]
[Prior art]
Devices that handle video and audio as digital data are becoming popular, and television broadcasting is also rapidly digitized. In digital broadcasting, it is possible to increase the number of channels compared to analog broadcasting, and various functions can be added according to program information distributed simultaneously with video and audio signals.
[0003]
For example, a receiving device that can receive digital satellite broadcast radio waves, digital terrestrial broadcast radio waves, and the like has a plurality of tuner circuits, and by operating these simultaneously, broadcast programs can be viewed in a timely manner as usual. In addition, some of them have a function that can be stored in a randomly accessible recording medium, such as an HDD (Hard Disc Drive), so that the immediately preceding video can be appropriately reproduced even while a broadcast program is being viewed. .
[0004]
However, in this case, high-frequency mutual interference caused by using a plurality of tuner circuits simultaneously becomes a problem. That is, the plurality of tuner circuits are in a state of receiving signals having a level difference with the same frequency from mutually independent parabolic antennas. At this time, a high-frequency current flows through each tuner circuit, and an electric field / magnetic field is generated around the tuner circuit by a radiated electromagnetic wave.
[0005]
Since each of the plurality of tuners is often mainly attached to the back panel side of a so-called set top box (STB), it is often impossible to ensure a sufficient spatial distance between the tuners. For this reason, the magnetic field and electric field generated from each of the plurality of tuner circuits may affect other tuner circuits, leading to serious radio wave interference such as a situation where the same channel interference occurs.
[0006]
Specifically, FIG. 8 shows a conventional tuner circuit. In general, the substrate 61 of the tuner circuit 51 is designed according to a so-called microstrip line configuration using the mount layer 62 and the ground layer 63, so that a large amount of high-frequency current flows on the mount layer 62 side. It has become. In such a configuration, particularly when the tuner circuits are used in parallel as shown in FIG. 8, an electromagnetic wave caused by a high-frequency current from the circuit group 64 on the mount layer 62 toward the adjacent tuner circuit 52. Is radiated. Further, a high-frequency current flows toward the ground layer 63 via the dielectric layer 65 that is capacitively coupled.
[0007]
Conventionally, in order to avoid such problems, cables are arranged in a set-top box so that a predetermined space is provided in the arrangement of a plurality of tuner units, or shield cases 66 and 67 in which metal parts are processed are used. Each tuner unit is covered tightly to take measures such as shielding electric and magnetic fields.
[0008]
[Problems to be solved by the invention]
However, shielding the tuner unit using the shield cases 66, 67, etc. leads to an increase in cost, and the distance between the substrates can be limited by the space of the shield case, so the placement of the tuner unit in the set top box is a problem. It was.
[0009]
In addition, high-frequency current also flows on the surface of the case due to the electric field and magnetic field generated in the space inside the shield case, so the high-frequency current that propagates through the shield case actually interferes with the other tuner circuit depending on the position of the placement. There was a risk of causing it.
[0010]
Therefore, the present invention has been proposed in view of such a conventional situation, and provides a signal receiving apparatus and a signal receiving circuit that reduce mutual interference that occurs when a plurality of tuners operate simultaneously with a simpler structure. The purpose is to do.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a signal receiving apparatus according to the present invention is included in an input means for inputting a broadcast wave obtained by modulating a video signal and an audio signal in a predetermined format, and included in a predetermined frequency band from the broadcast wave. A mount layer on which a circuit for selecting and demodulating a video signal and an audio signal is disposed, and a surface of the mount layer opposite to the circuit disposition surface on which the circuit is disposed is provided at a predetermined interval from the mount layer. The mount layer and the plurality of ground layers each include a plurality of signal receiving means stacked at a predetermined interval, and the signal receiving means is a certain signal receiving means. Decoding means for decoding the selected and demodulated video and audio signals in the frequency band, which are arranged adjacent to each other so that the ground layer located at the lowest layer of the signal layer and the circuit arrangement surface of another signal receiving means face each other When And output means for outputting a video signal and an audio signal which is the decoded to external equipment, the input means of said plurality of signal receiving means through the independent antenna is characterized by inputting the broadcast wave .
[0012]
Thereby, in the signal receiving apparatus according to the present invention, problems due to mutual interference caused by high frequency broadcast waves between a plurality of signal receiving means are reduced.
[0013]
Here, in particular, it is preferable to provide a dielectric layer between the mount layer and the uppermost ground layer and between each ground layer. Further, a plurality of signal receiving means may be provided for one broadcast wave, or a number corresponding to each of the plurality of broadcast waves may be provided.
[0014]
In order to achieve the above-mentioned object, a signal receiving circuit according to the present invention includes an input means for inputting a broadcast wave obtained by modulating a video signal and an audio signal in a predetermined format, and a predetermined frequency band from the broadcast wave. A mount layer on which a circuit for selecting and demodulating the included video signal and audio signal is disposed, and a surface of the mount layer opposite to the surface on which the circuit is disposed is provided at a predetermined interval from the mount layer. In place of the shield case, a plurality of ground layers that shield electromagnetic waves from the circuit are provided, and the mount layer and the plurality of ground layers are laminated at a predetermined interval, and capacitances between the layers are connected in series. It is characterized by being laminated so as to have a capacity .
[0015]
Here, it is particularly preferable to provide a dielectric layer between the mount layer and the uppermost ground layer and between the ground layers.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a tuner circuit and a signal receiving apparatus including the tuner circuit shown as specific examples of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a plan view of the substrate surface of the tuner circuit 1 as viewed from the side. The tuner circuit 1 is a circuit board in which a circuit for receiving a signal is designed on a multilayer board according to a microstrip line configuration, and receives and demodulates a broadcast wave modulated and transmitted in a predetermined format. . Here, for example, it has a circuit configuration for receiving a digital satellite broadcast wave (Digital Video Broadcast-Satellite; DVB-S).
[0018]
The tuner circuit 1 selects an input terminal 11 for inputting a broadcast wave obtained by modulating a video signal and / or an audio signal in a predetermined format, and a video signal and / or an audio signal included in a predetermined frequency band from the broadcast wave. And a mount layer 13 on which the main circuit 12 is disposed. In addition, a first ground layer 15 is provided on the opposite surface of the mount layer 13 from the surface on which the main circuit 12 is disposed via a first dielectric layer 14. Further, the tuner circuit 1 includes a second ground layer 17 via a second dielectric layer 16.
[0019]
Further, the main circuit 12 includes a capacitor 18 for cutting a direct current component and a resistor 19 for generating a bias voltage. An input broadcast wave receives these capacitor 18 and resistor 19. And is transmitted to the IC 20 via.
[0020]
Specifically, as shown in FIG. 2, the IC 20 includes an input terminal 21, an amplifier 22 that amplifies the input broadcast wave, an AGC (auto gain controller) 23 that adjusts the gain, and a BPF (BPF for extracting an intermediate frequency). A band-pass filter) 24, a Zero-IF 25 for extracting the I component and the Q component from the intermediate frequency, and a QPSK demodulation circuit 26 for demodulating a broadcast wave input from the I component and the Q component. Thereby, the broadcast wave modulated in a predetermined format taken in from the input terminal 11 is demodulated into a transport stream (TS).
[0021]
FIG. 3 shows a state of capacitive coupling between the mount layer 13, the dielectric layers 14 and 16, and the ground layers 15 and 17 as an equivalent circuit. Since the first ground layer 15 is interposed in the second ground layer 17 located on the opposite surface to the mount layer 13 that serves as an electromagnetic field radiation source, it can serve as a radiation source via two capacitors. It is coupled to the ground layer 17.
[0022]
As shown in FIG. 3, by providing two ground layers and a dielectric layer therebetween, the capacitance value between the substrate layers becomes the series capacitance of the two capacitors, so the coupling degree between each layer is the same. If there is a multilayer substrate, the substantial capacity can be reduced to ½ compared to the equivalent circuit of FIG.
[0023]
Therefore, the tuner circuit 1 having the above-described configuration includes the mount layer 13, the first ground layer 15, and the second ground layer 17, and between the mount layer 13 and the first ground layer 15, and By providing the first dielectric layer 14 and the second dielectric layer 16 between the first ground layer 15 and the second ground layer 17, respectively, the capacitor 18, the resistor 19, and the IC 20 are connected to the first dielectric layer 14 and the second dielectric layer 16. Since the high frequency current reaching the ground layer 15 can be shielded by the second dielectric layer 16 and the second ground layer 17, the level of the high frequency signal radiated from the second ground layer 17 can be efficiently reduced. .
[0024]
Next, the set top box 30 in which the above-described tuner circuit 1 is mounted will be described with reference to FIG. The set top box 30 shown in FIG. 5 has two tuner circuits arranged side by side, and can receive a signal having a level difference while having the same frequency. Therefore, for convenience of explanation, the tuner circuit 1 and the tuner circuit 2 are shown. However, in actuality, the configurations of both are the same and can be used without distinction. The tuner circuit 2 is distinguished by attaching “a” to the number.
[0025]
The set-top box 30 receives a transport stream from the tuner circuits 1 and 2, demultiplexes it, demultiplexes video, audio, data, and the like, and a MPEG (Moving Picture) taken out by the DEMUX 31. An MPEG decoder 32 for decoding video data and audio data compliant with the Experts Group) format, an image processing circuit 33, and a CPU 34 for overall management of these units are provided. These are connected to each other by a bus line 35. The set top box 30 includes an HDD 36 for recording video data, audio data, and the like, and a bus interface 37.
[0026]
In the set top box 30, the tuner circuits 1 and 2 are provided in front of the DEMUX 31. Specifically, as shown in FIG. 6, the second ground layer 17 of the tuner circuit 1 and the main circuit 12 a side of the tuner circuit 2 are arranged in parallel.
[0027]
Further, since radiation from the main circuit 12a generated in the ground layer 17 facing the mount layer 13a of the opposing tuner circuit 2 can hardly reach the main circuit 12 of the tuner circuit 1, interference does not easily occur.
[0028]
At this time, when the digital video broadcast-satellite (DVB-S) signal was actually received by one tuner circuit, the signal level received by the other tuner circuit was examined. The results are shown in FIG.
[0029]
In FIG. 7, the behavior indicated by A is the result when the same test is performed in the conventional tuner circuit shown in FIG. The behavior indicated by B is the case of the set top box 30 configured by arranging the tuner circuits 1 and 2 side by side.
[0030]
As is clear from FIG. 7, according to the tuner circuit 1 shown as this specific example, the radiation between adjacent tuner circuits can be suppressed by providing a plurality of ground layers. Therefore, it can be said that the mutual interference caused by the high-frequency current component is reduced and good reception characteristics can be obtained.
[0031]
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the tuner circuit is not limited to one corresponding to the same frequency. For example, each may have a tuner circuit corresponding to a plurality of broadcast waves.
[0032]
【The invention's effect】
As described above in detail, according to the signal receiving apparatus of the present invention, it is possible to reduce radio interference such as interference caused by mutual interference that occurs when a plurality of tuners arranged adjacent to each other operate simultaneously. In addition, compared to the conventional method of shielding electromagnetic waves using a metal shield case, it is possible to achieve the same or better effect with a simpler configuration, so that space saving and cost reduction can be achieved, and the device itself can be downsized. .
[0033]
Further, according to the signal receiving circuit of the present invention, it is possible to reduce radio wave interference such as interference due to mutual interference even when they are arranged adjacent to each other. In addition, compared to the conventional method of shielding electromagnetic waves using a metal shield case, it is possible to achieve the same or better effect with a simpler configuration, so that space can be saved, and this signal receiving circuit is used. Can be downsized.
[Brief description of the drawings]
FIG. 1 is a side view of a tuner circuit board shown as a specific example of the present invention.
FIG. 2 is a configuration diagram illustrating an IC unit of the tuner circuit.
FIG. 3 is a diagram showing the tuner circuit as an equivalent circuit.
FIG. 4 is a diagram showing a conventional tuner circuit as an equivalent circuit.
FIG. 5 is a configuration diagram illustrating an example of a set top box in which the tuner circuit is mounted.
FIG. 6 is a diagram for explaining an arrangement of a tuner circuit board in the set top box.
FIG. 7 is a diagram for explaining a relationship between a signal level of an interference wave detected by an adjacent tuner circuit when DVB-S is passed through the tuner circuit and this DVB-S signal level;
FIG. 8 is a diagram for explaining an arrangement of a conventional tuner circuit board in a set-top box.
[Explanation of symbols]
1, 2 tuner circuit, 11 input terminal, 12 main circuit, 13 mount layer, 14 first dielectric layer, 15 first ground layer, 16 second dielectric layer, 17 second ground layer, 18 capacitor , 19 resistors, 20 IC, 21 input terminals, 22 amplifiers, 23 AGC, 24 BPF, 25 Zero-IF, 26 QPSK demodulation circuit, 30 set-top box, 31 DEMUX, 32 MPEG decoder, 33 image processing circuit, 34 CPU , 35 bus line, 36 HDD, 37 bus interface

Claims (11)

Mount on which an input means for inputting a broadcast wave obtained by modulating a video signal and an audio signal in a predetermined format and a circuit for selecting and demodulating the video signal and the audio signal included in the predetermined frequency band from the broadcast wave are arranged And a plurality of ground layers spaced apart from the mount layer on the surface of the mount layer opposite to the circuit disposition surface where the circuit is disposed, and the mount layer and the plurality of grounds. The layer has a plurality of signal receiving means stacked at a predetermined interval,
The signal receiving means are arranged adjacent to each other so that a ground layer located in the lowermost layer of a certain signal receiving means and a circuit arrangement surface of another signal receiving means face each other.
Decoding means for decoding the selected and demodulated frequency band video and audio signals;
Output means for outputting the decoded video signal and audio signal to an external device,
The signal receiving apparatus according to claim 1, wherein the input means of the plurality of signal receiving means inputs the broadcast wave via independent antennas.   2. The signal receiving device according to claim 1, further comprising a dielectric layer between the mount layer and the ground layer located at the uppermost layer and between the ground layers.   2. The signal receiving apparatus according to claim 1, wherein a plurality of said signal receiving means are provided for one broadcast wave.   2. A signal receiving apparatus according to claim 1, wherein said signal receiving means is provided corresponding to each of a plurality of broadcast waves.   2. A signal receiving apparatus according to claim 1, further comprising recording means for storing the video signal and the audio signal.   2. The signal receiving apparatus according to claim 1, wherein the ground layer includes two layers.   2. The signal receiving apparatus according to claim 1, wherein the broadcast wave is a digital satellite broadcast wave, and the antenna is a parabolic antenna. Input means for inputting a broadcast wave obtained by modulating a video signal and an audio signal in a predetermined format;
A mount layer on which a circuit for selecting and demodulating a video signal and an audio signal included in a predetermined frequency band from the broadcast wave is disposed;
A plurality of ground layers that shield the electromagnetic waves from the circuit instead of a shield case that is provided at a predetermined interval on the surface opposite to the surface on which the circuit of the mount layer is disposed;
The signal receiving circuit, wherein the mount layer and the plurality of ground layers are laminated at a predetermined interval, and are laminated so that a capacitance between each layer becomes a series capacitance .   9. The signal receiving circuit according to claim 8, further comprising a dielectric layer between the mount layer and the ground layer located at the uppermost layer and between each ground layer.   9. The signal receiving circuit according to claim 8, wherein the ground layer includes two layers. 9. The circuit for selecting and demodulating comprises a band-pass filter for extracting an intermediate frequency from the broadcast wave, and a demodulation circuit for demodulating the broadcast wave input from the intermediate frequency. Signal receiving circuit.

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