JP4224720B2 - Television and broadcast signal receiver - Google Patents

Description

  The present invention relates to a television and a broadcast signal receiving apparatus.

Conventionally, in order to view cable television (CATV) broadcasting and further terrestrial digital broadcasting in addition to terrestrial analog broadcasting, a television 110 having a configuration as shown in FIG. 3 has been used.
In the figure, a case where a digital tuner block 102 for receiving a digital broadcast signal is further mounted in a state where the analog tuner block 101 for receiving an analog broadcast signal is provided. In such a configuration, the terrestrial analog broadcast reception antenna 105 is connected to the input terminal 108 of the analog tuner block 101 to enable reception of terrestrial analog broadcast, and the CATV broadcast cable 106 is connected to the input terminal 108. By reconnecting to 108, it was possible to receive CATV broadcasts.

  Further, in the above configuration, the signal processing circuit 103 receives the channel selection instruction by the user's remote control operation or the like, and thereby outputs the video signal output from the analog tuner block 101 and the video signal output from the digital tuner block 102. Alternatively, the display 104 was made to perform video display based on the selected video signal.

Furthermore, a television tuner is known in which a cable 7 for CATV broadcasting and a receiving antenna 8 for terrestrial FM broadcast signals are connected to the tuner unit 1 (see Patent Document 1).
Furthermore, a tuner unit having a terrestrial antenna input terminal that is a first antenna input terminal and a BS antenna input terminal that is a second input terminal is known (see Patent Document 2).
JP 2000-78490 A JP 2002-135668 A

  In the conventional television 110 described above, either the terminal of the antenna 105 or the cable 106 for CATV broadcasting is connected to the input terminal 108 of the analog tuner block 101. Therefore, when the user switches the viewing target between terrestrial analog broadcasting and CATV, it is necessary to change what is connected to the input terminal 108 of the analog tuner block 101, which is extremely complicated. In addition, if a common antenna is used for reception of terrestrial analog broadcasting and reception of terrestrial digital broadcasting, it is necessary to reconnect the antenna terminals between the analog tuner block 101 and the digital tuner block 102 in this case. Such work is also very complicated.

  Further, both of the above documents 1 and 2 are complicated switching physical connections of input cables in an environment having two analog television broadcast signal input systems and one digital television broadcast signal input system. It was not something to eliminate.

  Furthermore, simply mounting a plurality of tuner blocks on a television as in the prior art cannot eliminate the influence of noise generated by the circuits in each tuner block, and the quality of the image being viewed is reduced. There was a problem.

  The present invention has been made in view of the above problems, and reconnects input cables in an environment having two analog television broadcast signal input systems and one digital television broadcast signal input system. It is an object of the present invention to provide a television and a broadcast signal receiving apparatus that are completely unnecessary and that can minimize adverse effects due to noise generated by a plurality of tuner blocks.

In order to achieve the above object, the present invention is capable of inputting broadcast signals to each of a plurality of input systems, and corresponds to a channel designated by a channel selection instruction from the outside of each broadcast signal from each input system. In a broadcast signal receiving device that outputs a video signal generated based on a broadcast signal to a predetermined video signal processing circuit, the broadcast signal receiving device includes only an analog signal input terminal as an input terminal of the broadcast signal, and the first input from the analog signal input terminal. The analog dedicated input demodulation circuit that generates and outputs the first video signal based on one analog broadcast signal, and the second analog broadcast signal and digital broadcast signal can be received via the connected antenna. The second video signal is generated and output based on the second analog broadcast signal, and the received digital broadcast signal And a digital / analog common reception demodulation circuit that generates and outputs a third video signal, and selects one of the output video signals based on a predetermined channel selection instruction and outputs the video. And a selection control means for outputting to the signal processing circuit. That is, the selection control means accepts the channel selection instruction, selects a video signal corresponding to the channel specified by the channel selection instruction from the output video signals, and outputs the video signal to the video signal processing circuit.

  In the above configuration, the analog dedicated input demodulation circuit has only an analog signal input terminal as a broadcast signal input terminal. The first analog broadcast signal is input from the analog signal input terminal, and the first video signal is input. Is generated and output. On the other hand, the digital / analog shared reception demodulation circuit is connected to an antenna, and can receive the second analog broadcast signal and the digital broadcast signal via the antenna. Then, a second video signal is generated and output based on the received second analog broadcast signal, and a third video signal is generated and output based on the received digital broadcast signal. The selection control means selects one of the output first to third video signals based on a predetermined channel selection instruction and outputs the selected video signal to the video signal processing circuit.

  That is, according to the present invention, the analog dedicated input demodulation circuit can always connect a predetermined cable to maintain the reception state of the first analog broadcast signal, and the digital / analog common reception demodulation circuit can always connect the antenna. The second analog broadcasting signal and the digital broadcasting signal can be maintained, so that the first analog broadcasting signal is not required to reconnect the cable or antenna terminal to the tuner side. A desired broadcast signal can be selected from the second analog broadcast signal and the digital broadcast signal only by switching the channel.

According to the present invention, the analog dedicated input demodulation circuit is connected to a cable for transmitting an analog cable television broadcast signal at an analog signal input terminal. In other words, a cable for transmitting a cable television broadcast signal can always be connected to the analog dedicated input demodulation circuit, and the analog signal input terminal does not need to be shared with other analog broadcast signal input system cables. A cable TV broadcast signal is input from the analog signal input terminal.

In the present invention, the digital / analog common reception / demodulation circuit receives the terrestrial analog broadcast signal and the terrestrial digital broadcast signal via the antenna. That is, it is not necessary to cover the reception of analog broadcasts of two input systems with a tuner dedicated to analog broadcast signals having only one analog signal input terminal, and complicated cable reconnecting work is not necessary.

Here, if the analog dedicated input demodulation circuit and the digital / analog common reception demodulation circuit are mounted on the same device, it is considered that noise generated in each circuit adversely affects each other's operation and video output. . Accordingly, in the present invention, the selection control means is a predetermined unit provided for generating a video signal other than the selected video signal among the respective parts in the analog dedicated input demodulation circuit and the digital / analog common reception demodulation circuit. Control to stop the driving of the part is executed. In other words, as described above, a total of three broadcast signal input systems are provided, but at that time, the circuit portions that exist for the generation of the video signal that is not the object of viewing are stopped, so This eliminates the problem that the image being viewed is disturbed by noise from a circuit that is not connected.

  More specifically, the selection control means generates the first video signal by performing demodulation processing on the intermediate frequency signal extracted from the first analog broadcast signal, which is a part of the analog dedicated input demodulation circuit. A first demodulator that performs demodulation processing on the intermediate frequency signal extracted from the second analog broadcast signal, which is a part of the digital / analog shared reception demodulator circuit, and generates the second video signal. A predetermined demodulator for generating the third video signal by performing a demodulation process on the intermediate frequency signal extracted from the digital broadcast signal, which is a part of the digital / analog common reception demodulation circuit, The drive is stopped based on a predetermined condition. This is because the first demodulator, the second demodulator, and the IC each radiate a lot of noise.

That is, the selection control unit, when the channel selection instruction instructs the switch to the channel corresponding to the cable television broadcast signal of the analog stops the driving of the said IC second demodulator, the tuning When the instruction instructs switching to the channel corresponding to the terrestrial analog broadcast signal, the driving of the first demodulator and the IC is stopped, and the channel selection instruction is changed to the channel corresponding to the digital broadcast signal. When switching is instructed , the driving of the first demodulator and the second demodulator is stopped.
As a result, even when any one of the first to third video signals is selected, it is possible to realize a high-quality video display that eliminates the influence of noise from circuits not involved in video output.

Based on each of the above configurations, as another configuration of the present invention , broadcast signals can be input to each from a plurality of input systems, and each broadcast signal from each input system is designated by an external channel selection instruction. The video signal generated based on the broadcast signal corresponding to the channel is output to a predetermined video signal processing circuit, and the video is output to the display device based on the video signal after receiving the video processing in the video signal processing circuit. In the television to let
As a broadcast signal input terminal, a cable TV having only an analog signal input terminal for connection to a cable for transmitting an analog cable TV broadcast signal and input from the analog signal input terminal based on a predetermined channel selection control signal An analog tuner circuit that extracts and outputs an intermediate frequency signal from a broadcast signal, and performs amplification processing and demodulation processing on the intermediate frequency signal output from the analog tuner circuit to generate a first video signal, A tuner block dedicated to a cable having a first demodulation circuit for outputting a video signal;
An antenna connection terminal to which a shared antenna used for receiving terrestrial digital broadcast signals and terrestrial analog broadcast signals is connected, and terrestrial digital broadcast signals or terrestrial analog broadcast signals based on a predetermined channel selection control signal A digital / analog shared tuner circuit that extracts and outputs an intermediate frequency signal from the signal, and performs amplification processing and demodulation processing on the intermediate frequency signal extracted from the terrestrial analog broadcast signal to generate a second video signal. A second demodulating circuit that outputs a second video signal, and each IC that operates under the control of the microcomputer, which is connected to the microcomputer by a predetermined bus and serves as a master of bus communication. Front end IC for generating a transport stream signal based on the extracted intermediate frequency signal and the A digital-to-analog common tuner block having a back-end IC for a transport stream signal to input from the front-end IC generates a third image signal on the basis of the transport stream signal and outputs the same third video signal,
The microcomputer for receiving the channel selection instruction and selecting the video signal corresponding to the channel specified by the channel selection instruction from the output video signals and outputting the video signal to the video signal processing circuit,
When the channel selection instruction instructs switching to a channel corresponding to the analog cable television broadcast signal, the microcomputer cuts off the supply of power to the second demodulation circuit. The driving of the demodulating circuit is stopped, and a predetermined driving control signal is transmitted to the front end IC via the bus to stop the oscillation of the clock oscillation circuit built in the front end IC, thereby driving the front end IC. When the channel selection instruction instructs switching to a channel corresponding to the terrestrial analog broadcast signal, the power supply to the first demodulation circuit is cut off to Stop driving and stop driving the front end IC by stopping the oscillation of the clock oscillation circuit built in the front end IC. , If the channel selection instruction instructs the switch to the channel corresponding to the terrestrial digital broadcast signal, a first demodulation by blocking respectively the power supply to the first demodulator and the second demodulator circuit The driving of the circuit and the second demodulation circuit is stopped.

That is, a specific product called a television has the same operation and effect as the second aspect .

As described above, according to the present invention, when selecting a video signal based on one of two analog television broadcast signals and one digital television broadcast signal, the above three types of broadcast signals are selected. Since a desired broadcast signal can be selected while a cable or antenna necessary for input is always connected to the tuner, there is no need to reconnect the cable or antenna to the tuner.
In addition, when a video signal related to a certain input system is selected, the drive of the circuit part related to the generation of the video signal related to another input system is stopped, so that a high-quality video display that is always free from noise is displayed. It can be carried out.

FIG. 1 is a block diagram of a television 10 according to the present invention.
The television 10 generally includes components such as a cable-dedicated tuner block 20, a digital / analog shared tuner block 30, a signal processing block 40, a display 50, a microcomputer 60, and a power supply circuit 70.
The microcomputer 60 controls the driving of the entire television 10 and is electrically connected to the above components. The microcomputer 60 includes a CPU 61, a ROM 62, a RAM 63, and an interface (I / F) 64. That is, in the microcomputer 60, the CPU 61 controls the driving of the television 10 based on the program and data stored in the ROM 62 using the RAM 63 as a work area.

The power supply circuit 70 inputs the commercial AC power supply outside the television 10 through the cord 71, converts the AC power supply into a predetermined level of DC, and converts the converted DC voltage including the microcomputer 60 into the above-described DC voltage. Supply to each component. Note that the power supply to each unit by the power supply circuit 70 is also controlled by the microcomputer 60.
Next, the cable dedicated tuner block 20 and the digital / analog shared tuner block 30 will be described. In the present invention, by mounting the two tuner blocks, analog broadcast signals can be input to the two input systems and digital broadcast signals can be input.

  The cable-dedicated tuner block 20 is a device provided with only one analog signal input terminal 24 on the surface of the casing, and includes a tuner circuit 22 and a first analog demodulation circuit 23 inside. The analog signal input terminal 24 is connected to a cable 21 that transmits an analog CATV broadcast signal. That is, the cable dedicated tuner block 20 receives the CATV broadcast signal via the input terminal 24. The tuner circuit 22 has a so-called synthesizer type configuration. The tuner circuit 22 is supplied with PLL data as a channel selection control signal, that is, data of the frequency division ratio of the variable frequency dividing circuit in the PLL loop. The tuner circuit 22 receives transmission of PLL data as a channel selection control signal from the microcomputer 60, and receives an intermediate frequency of a desired frequency band from any one of broadcast signals corresponding to each channel of the CATV broadcast received via the cable 21. By extracting the signal (IF), one channel is selected from a plurality of channels.

  The microcomputer 60 recognizes the channel to be selected at that time by receiving the channel switching instruction signal transmitted by the user with a remote control transmitter or the like as an external device via the I / F 64, and determines the channel selected. A tuning control signal for receiving a television broadcast signal is transmitted to the cable dedicated tuner block 20 (or the digital / analog shared tuner block 30).

  The intermediate frequency signal output from the tuner circuit 22 is supplied to the first analog demodulation circuit 23. The first analog demodulation circuit 23 includes an amplification unit, a demodulation unit, and an NTSC decoder. The amplifying unit amplifies the gain of the supplied intermediate frequency signal to a predetermined level under a predetermined feedback control, and the demodulating unit separates the amplified intermediate frequency signal to obtain an analog video in NTSC format. A signal and an analog audio signal are generated. The generated analog video signal is input to an NTSC decoder and converted to a digital video signal by the NTSC decoder. The NTSC format is a standard format for analog television signals, and includes a signal for reproducing colors, a horizontal synchronizing signal of 15.75 kHz, a vertical synchronizing signal of 60 Hz, and the like. The demodulator is provided with a sync separation circuit for extracting a horizontal sync signal and a vertical sync signal, and the NTSC decoder is synchronized based on the horizontal sync signal and the vertical sync signal extracted by the sync separator circuit. A digital video signal (first video signal) is generated. The first video signal generated by the NTSC decoder is output to the signal processing block 40. The analog audio signal separated by the demodulator is supplied to a speaker (not shown).

  The digital / analog common tuner block 30 has an antenna connection terminal 32 on the surface of the housing, and the antenna connection terminal 32 is used for reception of terrestrial digital broadcast signals and reception of terrestrial analog broadcast signals. An antenna 31 is connected. The digital / analog common tuner block 30 includes a common tuner circuit 33, a second analog demodulation circuit 34, and a digital demodulation circuit 35.

  The shared tuner circuit 33 and the second analog demodulation circuit 34 share functions in common with the tuner circuit 22 and the first analog demodulation circuit 23 in the cable dedicated tuner block 20. That is, the shared tuner circuit 33 is based on the channel selection control signal transmitted from the microcomputer 60, and is based on either the terrestrial digital broadcast signal or the terrestrial analog broadcast signal corresponding to each channel received via the shared antenna 31. An intermediate frequency signal in a desired frequency band is extracted, and the intermediate frequency signal extracted from the terrestrial analog broadcast signal is supplied to the second analog demodulation circuit 34. Similar to the first analog demodulation circuit 23, the second analog demodulation circuit 34 generates the digital video signal (second video signal) by executing the amplification processing and demodulation processing on the intermediate frequency signal, and generates a signal processing block 40. Output to.

  When the intermediate frequency signal output from the shared tuner circuit 33 is extracted from the terrestrial digital broadcast signal, the intermediate frequency signal is supplied to the digital demodulation circuit 35. The digital demodulation circuit 35 includes a front end IC 36 and a back end IC 37. The front end IC 36 includes a digital I / F and a demodulation unit. The digital I / F to which the intermediate frequency signal is input has an A / D converter, and the demodulator that receives the signal from the digital I / F has a channel equalizer, an error correction decoder, and the like. That is, the digital I / F and the demodulator convert the input intermediate frequency signal into a digital signal, and perform so-called ghost cancellation on the digital demodulated signal based on the control information from the microcomputer 60. Further, the digital I / F and the demodulator correct a bit error generated on the transmission path to obtain a transport stream (TS) signal.

  The TS signal is output to the back-end IC 37. The back-end IC 37 includes a descrambling unit, a demultiplexing unit, and an MPEG decoder. Since the TS signal is normally scrambled, video and audio cannot be properly reproduced as it is. Therefore, the descrambling unit performs descrambling processing on the TS signal, thereby restoring the TS signal to a reproducible data array. The descrambled TS signal has a format in which video signals, audio signals, character information, and the like are multiplexed, and is supplied to the demultiplex. The demultiplex unit performs demultiplex processing on the input data. That is, multiplexing is released here.

  When the demultiplexing is canceled by the demultiplexing process, MPEG data in which the video signal and the audio signal are compressed by a predetermined method is obtained. The MPEG data is supplied to the MPEG decoder, and compression / decompression processing, that is, MPEG decoding processing is performed by the MPEG decoder. By this MPEG decoding process, a digital video signal (third video signal) and a digital audio signal are generated. The third video signal is output to the signal processing block 40. On the other hand, the digital audio signal is converted into an analog audio signal by a predetermined D / A converter, and the analog audio signal is output to a speaker (not shown).

  In this way, the first video signal generated by the first analog demodulation circuit 23 of the cable dedicated tuner block 20 and the second video signal generated by the second analog demodulation circuit 34 of the digital / analog shared tuner block 30. Both the signal and the third video signal generated by the digital demodulation circuit 35 are output to the signal processing block 40.

  In the signal processing block 40, a selection circuit 41 and a video signal processing circuit 42 are provided inside. The selection circuit 41 is a circuit that selects and outputs one of the input video signals in response to an instruction from the microcomputer 60. That is, since the microcomputer 60 can recognize the channel to be selected at that time in accordance with the operation of the user's remote control transmitter or the like, if the selected channel corresponds to the CATV broadcast signal, it is selected. When the circuit 41 selects the output (first video signal) from the first analog demodulation circuit 23 and the selected channel corresponds to the terrestrial analog broadcast signal, the selection circuit 41 receives the second analog signal. When the output from the demodulation circuit 34 (second video signal) is selected and the selected channel corresponds to the terrestrial digital broadcast signal, the selection circuit 41 causes the third signal from the digital demodulation circuit 35 to be selected. Select the video signal.

As a result, one video signal corresponding to the channel selected at that time is input to the video signal processing circuit 42 among the first to third video signals.
In the video signal processing circuit 42, when a digital video signal is input, the video signal is subjected to predetermined signal processing and output to the display 50. As the display 50, various video display devices such as a CRT, a liquid crystal panel, and a plasma display panel can be adopted. Here, a liquid crystal panel will be described as an example.

  The video signal processing circuit 42 includes a pixel number conversion circuit, an image quality adjustment circuit, and an output processing circuit. The pixel number conversion circuit receives a digital video signal and generates an RGB signal for one screen displayed on the liquid crystal panel while performing a scaling process on the video signal. The image quality adjustment circuit performs various adjustments such as brightness, contrast, black balance, white balance, and sharpness on the RGB signal that has been scaled by the pixel number conversion circuit. The output processing circuit performs gamma correction, dither processing, etc. on the RGB signal that has undergone image quality adjustment, adds a background signal, OSD signal, blanking signal, etc., and outputs it to the liquid crystal panel to display an image Let

  As described above, in the present invention, when all three types of broadcast signals of CATV broadcast, terrestrial analog broadcast, and terrestrial digital broadcast can be viewed on the television 10, the cable dedicated tuner block 20 and the digital / analog common use are provided. A tuner block 30 is mounted. As a result, the cable 21 for CATV broadcasting is always connected to the analog signal input terminal 24 of the tuner block 30 for exclusive use of the cable, and the shared antenna 31 is always connected to the antenna connection terminal 32 of the digital / analog shared tuner block 30. It is now possible to view the desired channel from all of the CATV broadcasting, analog terrestrial broadcasting, and digital terrestrial broadcasting by simply selecting the channel. That is, when switching between a plurality of channels including CATV broadcasting, terrestrial analog broadcasting, and terrestrial digital broadcasting as in the past, the complicated work of reconnecting the terminals of the cable and antenna and the terminal on the tuner side as appropriate, No longer needed.

Here, if the cable dedicated tuner block 20 and the digital / analog shared tuner block 30 are simply mounted on the television 10, there is a possibility that the image quality of the video being viewed is deteriorated due to noise generated by each tuner block. . Therefore, in the present embodiment, the following noise countermeasures are taken.
FIG. 2 is a flowchart showing the contents of the on / off switching process of each tuner block executed by the television 10. This process is executed by the microcomputer 60 on the assumption that the main power supply of the television 10 is in the input state and the television 10 is in the driving state. That is, it is executed together with the processing from the reception of the broadcast signal to the video display as described above.

  First, in step S (hereinafter step description is omitted) 200, the microcomputer 60 determines whether there is an instruction to switch channels from the outside. The microcomputer 60 can determine whether or not there has been a channel switching instruction based on whether or not the channel switching instruction signal has been received via the I / F 64.

If there is no channel switching instruction, the flow ends. However, this flow is repeatedly executed at predetermined intervals while the television 10 is being driven.
When there is a channel switching instruction, the microcomputer 60 determines whether or not the switching instruction is an instruction to switch to a channel corresponding to CATV broadcasting (S210). In a predetermined storage device such as ROM 62, a correspondence relationship between each channel number and information for distinguishing between a channel corresponding to CATV broadcasting, a channel corresponding to terrestrial analog broadcasting, or a channel corresponding to terrestrial digital broadcasting is defined in advance. The information table is stored, and the microcomputer 60 makes the above determination with reference to the switching destination channel number and the information table when the switching instruction is given.

  If the switching instruction is an instruction to switch to a channel corresponding to CATV broadcast, the microcomputer 60 drives the first analog demodulation circuit 23 of the cable-only tuner block 20 in S220. When the channel before switching is not a channel corresponding to CATV broadcasting, as will be described later, in the present embodiment, the first analog demodulation circuit 23 is in a drive stop state. For this reason, in S220, it is confirmed whether or not the first analog demodulation circuit 23 is in the drive stop state, and if it is in the drive stop state, it is driven. Of course, if the channel before switching is also a channel corresponding to CATV broadcasting, the first analog demodulator circuit 23 is already in a driving state, so in S220, the first analog driver circuit 23 is driven without performing any particular processing. What is necessary is just to maintain a state.

  If the determination in S210 is “No”, the microcomputer 60 determines in S230 whether or not the switching instruction is an instruction to switch to a channel corresponding to terrestrial analog broadcasting. If the switching instruction is an instruction to switch to a channel corresponding to terrestrial analog broadcasting, the second analog demodulation circuit 34 of the digital / analog shared tuner block 30 is driven in S240. That is, as in S220, the second analog demodulation circuit 34 is driven when the drive is stopped at that time, and when it is already in the drive state, the drive state of the second analog demodulation circuit 34 is changed without any particular processing. maintain.

If the determination in S230 is “No”, that is, if the switching instruction is an instruction to switch to a channel corresponding to terrestrial digital broadcasting, in S250, the microcomputer 60 uses the digital / analog shared tuner block. 30 digital demodulation circuits 35 are driven . Also in this case, the digital demodulating circuit 35 is driven when the driving is stopped at that time, and when it is already in the driving state, the driving state of the digital demodulating circuit 35 is maintained without any particular processing.

  Here, in the present embodiment, when the first analog demodulation circuit 23 and the second analog demodulation circuit 34 are referred to as being in a drive stop state, the power supply from the power supply circuit 70 to each demodulation circuit is cut off. To do. Therefore, the microcomputer 60 may restart the power supply from the power supply circuit 70 to the respective demodulating circuits in order to bring the first analog demodulating circuit 23 and the second analog demodulating circuit 34 into the driving state.

  On the other hand, in the present embodiment, when the digital demodulation circuit 35 is said to be in the drive stop state, the oscillation of the clock oscillation circuit built in the front end IC 36 of the digital demodulation circuit 35 is stopped to drive the front end IC 36 in the drive stop state. Means that In this case, the power supply itself from the power supply circuit 70 to the digital demodulation circuit 35 (the front end IC 36 and the back end IC 37) is maintained. Therefore, the microcomputer 60 may resume the oscillation of the clock oscillation circuit of the front-end IC 36 in order to set the digital demodulation circuit 35 in the driving state.

  After S220, the microcomputer 60 executes a process of stopping the driving of the second analog demodulation circuit 34 and the front end IC 36 (S260). That is, the microcomputer 60 performs control to cut off the power supply from the power supply circuit 70 to the second analog demodulation circuit 34 and stops the oscillation of the clock oscillation circuit built in the front end IC 36. Here, the microcomputer 60 is connected to the front-end IC 36 and the back-end IC 37 by an inter-IC communication bus 80, and the microcomputer 60 serves as a master for this bus communication. Therefore, the microcomputer 60 transmits a control signal to the front end IC 36 via the bus 80 to stop the clock oscillation. Even when the clock oscillation of the front end IC 36 is restarted, the microcomputer 60 sends an instruction signal to the front end IC via the bus 80.

  When a channel for CATV broadcasting is selected, the operation of the digital / analog shared tuner block 30 is not necessary. Therefore, by stopping the driving of the second analog demodulation circuit 34 and the front-end IC 36 that are particularly likely to generate noise among the digital / analog shared tuner block 30 as described above, the digital digital / analog tuner block 30 receives digital data when receiving CATV broadcasts and outputting video. -The influence of noise from the analog shared tuner block 30 is prevented from appearing. Further, regarding the front end IC 36, when the driving is stopped, the power supply itself is not interrupted but only the clock is stopped, so that the time required for starting up when restarting the drive later is short. It is also possible to prevent various data recorded in the volatile memory from being erased every time driving is stopped.

  After S240, the microcomputer 60 executes a process for stopping the driving of the first analog demodulation circuit 23 and the front end IC 36 (S270). The microcomputer 60 realizes the drive stop of the first analog demodulation circuit 23 by cutting off the power supply from the power supply circuit 70 to the first analog demodulation circuit 23. The driving stop of the front end IC 36 is the same as S260.

  When a channel related to terrestrial analog broadcasting is selected, the operation of the digital demodulation circuit 35 in the cable dedicated tuner block 20 and the digital / analog common tuner block 30 is unnecessary. Therefore, as described above, by stopping the driving of the first analog demodulator circuit 23 and the front end IC 36 that are particularly likely to generate noise in the cable dedicated tuner block 20, the reception of the terrestrial analog broadcast and the video output are stopped. At that time, the influence of noise from unnecessary peripheral circuits is prevented from appearing.

  After S250, the microcomputer 60 executes processing for stopping the driving of the first analog demodulation circuit 23 and the second analog demodulation circuit 34 (S280). This is because when the channel for terrestrial digital broadcasting is selected, the operation of the second analog demodulation circuit 34 in the cable dedicated tuner block 20 and the digital / analog shared tuner block 30 is unnecessary. As a result, when receiving terrestrial digital broadcast and outputting video, unnecessary noise from peripheral circuits does not appear at that time.

  In the above description, in the scene where the first analog demodulation circuit 23 is set to the drive stop state or the drive state, the cable dedicated tuner block 20 itself may be set to the drive stop state or the drive state. . This is because the drive of the cable dedicated tuner block 20 itself may be stopped when a channel for terrestrial analog broadcasting or terrestrial digital broadcasting is selected.

  As described above, in the present invention, the cable-dedicated tuner block 20 and the digital / analog shared tuner block 30 are mounted on the television 10, thereby eliminating the need to change the connection between the cable or antenna terminal and the tuner terminal. At the same time, it has become possible to suppress adverse effects on peripheral circuits due to radiation noise from each tuner block, which are caused by the cable dedicated tuner block 20 and the digital / analog shared tuner block 30 coexisting at a close distance. As a result, it is possible to obtain a high-quality image even when viewing any of CATV broadcasting, terrestrial analog broadcasting, and terrestrial digital broadcasting.

The block diagram which showed schematic structure of the television concerning this invention. The flowchart which showed the on / off switching process of each tuner block. The block diagram which showed schematic structure of the television for performing the viewing / listening of the conventional CATV broadcast, terrestrial analog broadcast, and terrestrial digital broadcast.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Television 20 ... Tuner block for cables 21 ... Cable 22 ... Tuner circuit 23 ... First analog demodulation circuit 24 ... Analog signal input terminal 30 ... Digital / analog common tuner block 31 ... Shared antenna 32 ... Antenna connection terminal 33 ... Shared Tuner circuit 34 ... second analog demodulation circuit 35 ... digital demodulation circuit 36 ... front end IC
37 ... Backend IC
DESCRIPTION OF SYMBOLS 40 ... Signal processing block 41 ... Selection circuit 42 ... Video signal processing circuit 50 ... Display 60 ... Microcomputer 61 ... CPU
62 ... ROM
63 ... RAM
64 ... I / F
70 ... Power supply circuit 80 ... Inter-IC communication bus

Claims (2)

A broadcast signal can be input to each of a plurality of input systems, and a video signal generated based on a broadcast signal corresponding to a channel specified by a channel selection instruction from the outside of each broadcast signal from each input system. In a television that outputs to a predetermined video signal processing circuit and outputs a video to a display device based on a video signal after undergoing video processing in the video signal processing circuit,
As a broadcast signal input terminal, a cable TV having only an analog signal input terminal for connection to a cable for transmitting an analog cable TV broadcast signal and input from the analog signal input terminal based on a predetermined channel selection control signal An analog tuner circuit that extracts and outputs an intermediate frequency signal from a broadcast signal, and performs amplification processing and demodulation processing on the intermediate frequency signal output from the analog tuner circuit to generate a first video signal, A tuner block dedicated to a cable having a first demodulation circuit for outputting a video signal;
An antenna connection terminal to which a shared antenna used for receiving terrestrial digital broadcast signals and terrestrial analog broadcast signals is connected, and terrestrial digital broadcast signals or terrestrial analog broadcast signals based on a predetermined channel selection control signal A digital / analog shared tuner circuit that extracts and outputs an intermediate frequency signal from the signal, and performs amplification processing and demodulation processing on the intermediate frequency signal extracted from the terrestrial analog broadcast signal to generate a second video signal. A second demodulating circuit that outputs a second video signal, and each IC that operates under the control of the microcomputer, which is connected to the microcomputer by a predetermined bus and serves as a master of bus communication. Front end IC for generating a transport stream signal based on the extracted intermediate frequency signal and the A digital-to-analog common tuner block having a back-end IC for a transport stream signal to input from the front-end IC generates a third image signal on the basis of the transport stream signal and outputs the same third video signal,
The microcomputer for receiving the channel selection instruction and selecting the video signal corresponding to the channel specified by the channel selection instruction from the output video signals and outputting the video signal to the video signal processing circuit,
And the microcomputer is
When the channel selection instruction instructs switching to a channel corresponding to the analog cable TV broadcast signal, the driving of the second demodulation circuit is stopped by shutting off the power supply to the second demodulation circuit In addition, by transmitting a predetermined drive control signal to the front end IC via the bus, the oscillation of the clock oscillation circuit built in the front end IC is stopped and the driving of the front end IC is stopped,
When the channel selection instruction instructs switching to a channel corresponding to the terrestrial analog broadcast signal, the drive of the first demodulation circuit is stopped by shutting off the power supply to the first demodulation circuit At the same time, the driving of the front end IC is stopped by stopping the oscillation of the clock oscillation circuit built in the front end IC.
When the channel selection instruction instructs switching to a channel corresponding to the terrestrial digital broadcast signal, the power supply to the first demodulator circuit and the second demodulator circuit is cut off, respectively. And a television set characterized by stopping driving of the second demodulation circuit. A broadcast signal can be input to each of a plurality of input systems, and a video signal generated based on a broadcast signal corresponding to a channel specified by a channel selection instruction from the outside of each broadcast signal from each input system. In a broadcast signal receiving device that outputs to a predetermined video signal processing circuit,
As an input terminal for the broadcast signal, only an analog signal input terminal connected to a cable for transmitting an analog cable TV broadcast signal is provided, and the intermediate frequency signal extracted from the cable TV broadcast signal input from the analog signal input terminal is demodulated. An analog dedicated input demodulation circuit comprising a first demodulator that performs processing to generate and output a first video signal;
Connect to an antenna capable of receiving terrestrial analog broadcast signals and digital broadcast signals, and generate a second video signal by performing demodulation processing on the intermediate frequency signal extracted from the received terrestrial analog broadcast signal Digital / analog common reception comprising: a second demodulator for outputting; and a predetermined IC for generating and outputting a third video signal by executing a demodulation process on the intermediate frequency signal extracted from the received digital broadcast signal A demodulation circuit;
Selection control means for receiving the channel selection instruction and selecting the video signal corresponding to the channel specified by the channel selection instruction from the output video signals and outputting the video signal to the video signal processing circuit ;
When the channel selection instruction instructs switching to a channel corresponding to the analog cable television broadcast signal, the selection control means stops driving the second demodulator and the IC, and selects the channel selection instruction. Instructing to switch to the channel corresponding to the terrestrial analog broadcast signal, the driving of the first demodulator and the IC is stopped, and the channel selection instruction is sent to the channel corresponding to the digital broadcast signal. The broadcast signal receiving apparatus , wherein when switching is instructed, driving of the first demodulator and the second demodulator is stopped .

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