JP2006333126A - Television - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a television capable of registering only channels which can be received with high quality. <P>SOLUTION: When an RF-AGC voltage is higher than 3.1V, it is decided that there is not receivable television radio wave in a carrier frequency band made to correspond to a selected channel. An absolute threshold is set to the RF-AGC voltage and then spurious components of a television radio wave can securely be excluded from objects of channel registration. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a television, and more particularly, to a television including a channel selection unit that selects a television wave having a carrier frequency corresponding to a channel to be received and generates an intermediate frequency signal from the selected television wave.

Conventionally, as this type of television, when a plurality of channel selection data of the same broadcast is detected, a channel selection data having a higher AGC voltage is selected and stored (for example, see Patent Document 1). ).
According to such a configuration, only channels with a high AGC voltage can be registered in the channel selection data of the same broadcast, so unnecessary channels can be reduced. Further, channel selection can be performed by using channel selection data having a high AGC voltage and a large signal strength, and it has been possible to reproduce a high-quality video.

JP-A-9-162704

However, in the above-described television, even if the AGC voltage is absolutely low, the channel selection data is not deleted if the AGC voltage is relatively higher than the other channel selection data. There is a problem that even channels that cannot be played are registered.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a television that can register only channels that can be received with high quality.

In order to achieve the above object, according to a second aspect of the present invention, there is provided a television including a channel selecting means for selecting a television wave having a carrier frequency corresponding to a received channel and generating an intermediate frequency signal from the selected television wave. In John
Amplifying means for acquiring an AGC voltage corresponding to the signal strength of the intermediate frequency signal and amplifying the intermediate frequency signal by an amplification factor based on the AGC voltage, and the signal strength of the intermediate frequency signal is large based on the AGC voltage If it is recognized that the TV radio wave corresponding to the carrier frequency selected by the channel selection means is present, and the TV radio wave corresponding to the determination means is present. Channel storage means for storing the determined carrier frequency in association with the channel is provided.

  In claim 2 configured as described above, a desired channel can be received by selecting a television wave having a carrier frequency corresponding to the channel received by the channel selection means. The channel selection means generates an intermediate frequency signal based on the received television radio wave. The amplifying means detects the signal intensity of the intermediate frequency signal and generates an AGC voltage corresponding thereto. Then, the intermediate frequency signal is amplified by an amplification factor based on the AGC voltage. That is, the amplification means performs feedback control for adjusting the signal strength based on the signal strength of the intermediate frequency signal.

  The determining means determines the magnitude of the signal strength of the intermediate frequency signal by evaluating the AGC voltage. Then, when it is determined that the signal intensity of the intermediate frequency signal is high, the determination unit determines that the television radio wave corresponding to the carrier frequency selected by the channel selection unit is present. Then, the channel storage means stores only the carrier frequency determined by the determination means that the corresponding television radio wave exists, in association with the channel. By doing so, since the carrier frequency at which the signal strength of the intermediate frequency signal becomes small is not stored, it is possible to prevent the spurious signal from being erroneously stored and registering many channels unnecessarily.

According to a third aspect of the present invention, the determination means recognizes that the signal strength of the intermediate frequency signal is high based on a comparison result between the AGC voltage and a predetermined threshold value.
In the invention of claim 3 configured as described above, the AGC voltage is compared with a predetermined threshold value, and it is determined that the signal strength of the intermediate frequency signal is large based on the comparison result. That is, when the AGC voltage exceeds or falls below an absolute reference threshold, it can be determined that the signal strength of the intermediate frequency signal is high.

  Furthermore, the invention according to claim 4 further comprises synchronization signal detection means for detecting a synchronization signal from the intermediate frequency signal, and the determination means detects the synchronization signal and detects the synchronization signal based on the AGC voltage. When it is recognized that the signal strength of the intermediate frequency signal is high, it is determined that the television radio wave corresponding to the carrier frequency selected by the channel selection means is present.

  In the invention of claim 4 configured as described above, the synchronization signal detecting means detects the synchronization signal from the intermediate frequency signal. And only when it is recognized that the signal strength of the intermediate frequency signal is high after the synchronization signal is detected, the TV radio wave corresponding to the carrier frequency selected by the channel selection means is present. It is determined that Therefore, it is possible to prevent the influence of a noise signal that does not include the synchronization signal.

  The invention according to claim 5 further comprises frequency correction means for detecting an AFT voltage corresponding to a frequency shift of the intermediate frequency signal with respect to a reference frequency and correcting the frequency of the intermediate frequency signal based on the AFT voltage. In addition, when the AFT voltage is within a predetermined range and the signal strength of the intermediate frequency signal is recognized to be high based on the AGC voltage, the determination unit selects the channel selection unit. It is configured to determine that the television radio wave corresponding to the carrier frequency is present.

  In the invention according to claim 5 configured as described above, the frequency correction means detects an AFT voltage corresponding to a frequency shift with respect to a reference frequency of the intermediate frequency signal, and based on the AFT voltage, Correct the frequency. That is, the frequency correction means performs feedback control for adjusting the frequency of the intermediate frequency signal based on the actual frequency of the intermediate frequency signal. Then, after it is determined that the frequency of the intermediate frequency signal is an appropriate value and the signal strength of the intermediate frequency signal is recognized to be high, the carrier selected by the channel selection means is selected. It is determined that the TV radio wave corresponding to the frequency exists. Therefore, it is possible to prevent the influence of a noise signal whose frequency is far from the intermediate frequency signal.

In the invention according to claim 6, the determination means is provided in the microcomputer, and the AGC voltage is input to the microcomputer as a digital signal via the A / D port.
In the invention of claim 6 configured as described above, the microcomputer causes the function of the determination means to be executed. The AGC voltage is input as a digital signal through an A / D port provided in the microcomputer. Therefore, the microcomputer can handle the AGC voltage.

Based on the above configuration, the invention of claim 1 is a television including a channel selection means for selecting a television wave having a carrier frequency corresponding to a channel to be received and generating an intermediate frequency signal from the selected television wave. In John
A SAW filter for adjusting the frequency characteristics of the intermediate frequency signal; an amplification means for acquiring an AGC voltage corresponding to the signal strength of the intermediate frequency signal; and amplifying the intermediate frequency signal by an amplification factor based on the AGC voltage; A synchronization signal detecting means for detecting a synchronization signal from the intermediate frequency signal, and an AFT voltage corresponding to a frequency shift with respect to a reference frequency of the intermediate frequency signal are detected, and the frequency of the intermediate frequency signal is corrected based on the AFT voltage. A frequency correction means; a microcomputer for inputting the AGC voltage as a digital signal from the A / D port when the synchronization signal is detected and the AFT voltage is in a predetermined range; When the AGC voltage is compared with a predetermined threshold, and the comparison result shows that the signal strength of the intermediate frequency signal is large. A determination unit that determines that the TV radio wave corresponding to the carrier frequency selected by the channel selection unit is present, and a carrier frequency that is determined by the determination unit to be present as the corresponding TV radio wave exists. Channel storage means for storing the data in the EEPROM in association with the channel.

  Needless to say, in such a more specific configuration, the same effects as the inventions of claims 2 to 6 described above can be obtained.

As described above, according to the first and second aspects of the invention, it is possible to provide a television that can register only channels that can be received with high quality.
According to the third aspect of the present invention, it is possible to prevent registration of a channel whose signal intensity is lower than a certain value.
According to the fourth aspect of the present invention, it is possible to prevent a channel from which no synchronization signal is detected from being registered.
According to the invention of claim 5, it is possible to prevent registration of a channel having an illegal frequency.
According to the invention of claim 6, the determination can be performed using a microcomputer.

Here, embodiments of the present invention will be described in the following order.
(1) Television configuration:
(2) Channel registration operation:
(3) Summary:

(1) Television configuration:
FIG. 1 is a schematic block diagram showing a television according to an embodiment of the present invention. In the figure, only the video signal processing system is shown for simplification of the figure. The television 10 includes a tuner 11, a SAW (Surface Acoustic Wave) filter 12, an intermediate frequency amplification circuit 13, a video detection circuit 14, a video signal processing circuit 15, an AGC circuit 16, an AFT circuit 17, an EEPROM 18, and a microcomputer 19. ing. In addition, an antenna 30 is connected to the television 10 via an antenna terminal 10 a, and a terrestrial television wave received by the antenna 30 is input to the tuner 11. The tuner 11 selects a carrier frequency at which a television radio wave is carried for each channel, and generates an intermediate frequency signal by a local transmission circuit. The tuner 11 employs a so-called PLL synthesizer tuning method, and can control the receivable frequency by selecting the division ratio of various fixed frequency dividers and variable frequency dividers. Yes, such frequency control is performed in accordance with a control signal sent from the microcomputer 19.

  The microcomputer 19 includes a CPU 19a, a ROM 19b, and a RAM 19c connected by a bus 19d. A / D ports 19e and 19f are connected to the bus 19d. The CPU 19a reads the control program stored in the ROM 19b, and executes processing according to the control program while using the RAM 19c as a work area. An RF-AGC voltage is input to the A / D port 19e, and an AFT voltage is input to the other A / D port 19f. The RF-AGC voltage and the AFT voltage are DC voltages that change within a predetermined range, but are converted into digital signals according to the voltage value of the DC voltage via the A / D ports 19e and 19f.

  An EEPROM 18 is connected to the outside of the microcomputer 19, and a channel data table T1 is stored in the EEPROM 18. FIG. 2 shows the contents described in the channel data table T1. In the figure, a carrier frequency for carrying a television wave corresponding to each channel number is stored. When the microcomputer 19 receives the designation of the channel by operating the operation panel or the remote controller, the microcomputer 19 specifies the carrier frequency corresponding to the designated channel from the channel data table T1, and sets the specified carrier frequency in the tuner 11. Output a control signal.

  By doing so, the tuner 11 can receive the TV radio wave of the designated channel. Note that the carrier frequency corresponding to each channel may be stored in the channel data table T1, and the division ratios of the fixed frequency divider and variable frequency divider in the tuner 11 set corresponding to each carrier frequency are stored. May be. In any case, there is no doubt that the correspondence between the carrier frequency received by the tuner 11 and the channel is defined. The EEPROM 18 is rewritable, and the channel data table T1 can be newly created or updated.

  A SAW (Surface Acoustic Wave) filter 12 receives an intermediate frequency signal and optimizes the frequency band of the surface wave of the intermediate frequency signal. The signal intensity of the intermediate frequency signal generated by the tuner 11 varies from channel to channel depending on the state of the input television wave. Therefore, the signal intensity is adjusted by the tuner 11 and the intermediate frequency amplifier circuit 13. The amplification factor when the tuner 11 amplifies the intermediate frequency signal is controlled based on the RF-AGC voltage, and the amplification factor when the intermediate frequency amplifier circuit 13 amplifies the intermediate frequency signal is controlled based on the IF-AGC voltage. The Both the RF-AGC voltage and the IF-AGC voltage are generated by the AGC circuit 16, and a composite video signal that has passed through the intermediate frequency amplification circuit 13 and the video detection circuit 14 is input to the AGC circuit 16.

  The AGC circuit 16 acquires a composite video signal that is an intermediate frequency signal output from the video detection circuit 14, and generates an RF-AGC voltage and an IF-AGC voltage corresponding to the composite video signal. Specifically, when the signal strength of the composite video signal is high, a low RF-AGC voltage and an IF-AGC voltage are generated, and when the signal strength of the composite video signal is low, a high RF-AGC voltage and IF-AGC are generated. Generate voltage. In the RF-AGC voltage, the voltage level varies between 0 and 5V. The RF-AGC voltage is input to the tuner 11, and the amplification factor of the intermediate frequency signal in the tuner 11 is increased as the RF-AGC voltage is higher. As described above, since the amplification rate of the intermediate frequency signal in the tuner 11 is feedback controlled by the RF-AGC voltage based on the signal strength of the composite video signal after amplification, the signal strength of the intermediate frequency signal or composite video signal is ideal. Can converge to a value. The tuner 11 that amplifies the intermediate frequency signal based on the RF-AGC voltage corresponds to the amplification means of the present invention.

  Similarly, the IF-AGC voltage is input to the intermediate frequency amplifier circuit 13, and the amplification factor of the intermediate frequency signal in the tuner 11 is increased as the IF-AGC voltage is higher. Also in the intermediate frequency amplifier circuit 13, since the amplification factor of the intermediate frequency signal is feedback controlled by the IF-AGC voltage based on the signal strength of the composite video signal after amplification, the signal strength of the intermediate frequency signal or composite video signal is ideal. Can be converged to any value. The intermediate frequency signal output from the intermediate frequency amplifier circuit 13 is input to the video detection circuit 14, and a composite video signal is extracted by the video detection circuit 14.

  The frequency of the intermediate frequency signal generated by the tuner 11 is preferably 58.75 MHz, but an error occurs depending on the reception state of the television radio wave. Therefore, an AFT circuit 17 is provided, and the AFT circuit 17 generates an AFT voltage based on the frequency of the intermediate frequency signal in the intermediate frequency amplifier circuit 13. Specifically, a video carrier is taken out from the intermediate frequency signal of the intermediate frequency amplifier circuit 13, and a voltage corresponding to the difference between the video carrier and the reference frequency (58.75 MHz) is generated by the FM detection circuit. AFT voltage is generated by DC amplification. In the tuner 11 to which the AFT voltage is input, the frequency of the intermediate frequency signal is converged to 58.75 MHz by applying the AFT voltage to the local transmission circuit. In this sense, the tuner 11 and the AFT circuit 17 correspond to the frequency correction means of the present invention. When the frequency of the intermediate frequency signal is shifted to the low frequency side, a high AFT voltage is output, and the transmission frequency in the local transmission circuit increases. On the other hand, when the frequency of the intermediate frequency signal is shifted to the high frequency side, a low AFT voltage is output, and the transmission frequency in the local transmission circuit is lowered.

  On the other hand, the composite video signal output from the video detection circuit 14 is input to the video signal processing circuit 15. The composite video signal is a composite wave in which the luminance signal, the carrier color signal, and the synchronization signal are combined. The video signal processing circuit 15 performs a process of separating the composite video signal into the above signals. In particular, the video signal processing circuit 15 is provided with a synchronization separation circuit 15a, from which a vertical synchronization signal and a horizontal synchronization signal are extracted. If a synchronization signal is detected by the synchronization separation circuit 15a, a synchronization detection signal to that effect is output to the microcomputer 19.

(2) Channel registration operation:
In the configuration of the television 10 described above, a process for registering a channel is executed. The ROM 19 of the microcomputer 19 stores a control program for executing the process, and the CPU 19 executes a process based on the control program. FIG. 3 shows the flow of channel registration processing executed by the microcomputer 19. In the figure, a channel to be registered is selected in step S100. In the present embodiment, the carrier frequencies of all channels that can be received including AIR broadcasts and CATV are stored as defaults, and by performing the processing described later for each channel, the TV radio waves that can be received at each carrier frequency are stored. Existence is verified. Then, only the data on the carrier frequency verified that there is a receivable television wave is left in the channel data table T1.

  In step S110, the carrier frequency corresponding to the selected channel is acquired from the channel data table T1. Then, the microcomputer 19 sends a control signal to the tuner 11 so as to receive the carrier frequency band. In step S120, it is determined whether or not a synchronization signal has been detected based on the synchronization detection signal input from the synchronization separation circuit 15a. If the synchronization signal is not detected, the data for the channel is deleted in step S125, and the process returns to step S110. That is, assuming that there is no receivable television wave in the carrier frequency band associated with the previously selected channel, the process for the next channel is executed without registering the channel in the channel data table T1.

  In step S120, the carrier frequency may be shifted within a predetermined range around the carrier frequency initially set in step S110. In this way, some carrier frequency can be allowed. However, if the number of times the carrier frequency is shifted increases, processing takes time, so it is desirable to limit the number of shifts to about two.

  On the other hand, if the synchronization signal is detected, the digitized AFT voltage is acquired through the A / D port 19f in step S130. In step S140, it is determined whether the AFT voltage is within a predetermined range. Since the AFT voltage means a frequency shift of the intermediate frequency signal, it can be said that the frequency of the received signal is not normal when the value of the AFT voltage is not normal. Therefore, if the value of the AFT voltage is not normal, the data for the channel is deleted in step S145, and the process returns to step S110. That is, assuming that there is no receivable television wave in the carrier frequency band associated with the previously selected channel, the process for the next channel is executed without registering the channel in the channel data table T1.

  For example, if the allowable range of the AFT voltage is set so that the frequency shift is within ± 50 kHz, it can be determined whether or not an appropriate television wave is present. Note that the appropriateness of the AFT voltage may be determined in consideration of the variation state of the AFT voltage value. For example, the carrier frequency received by the tuner 11 is gradually shifted, and if the AFT voltage is monotonously increasing or monotonically decreasing within the allowable range, the AFT voltage is determined to be appropriate. Also good.

  On the other hand, if it is an appropriate AFT voltage, the digitized RF-AGC voltage is acquired via the A / D port 19f in step S150. In step S160, it is determined that the RF-AGC voltage is 3.1 V or less as a threshold value. Thus, it can be said that the microcomputer 19 that determines the RF-AGC voltage in step S150 includes the determination means of the present invention. Since the RF-AGC voltage decreases as the signal strength of the intermediate frequency signal increases, it can be determined that the signal strength of the intermediate frequency signal is high when the RF-AGC voltage is 3.1 V or less. If the RF-AGC voltage is 3.1 V or less, it can be said that the signal strength of the intermediate frequency signal is about 50 dB or more, and that an effective television wave is received.

  If the RF-AGC voltage is greater than 3.1 V, the process returns to step S110 to execute processing for the next channel. That is, assuming that there is no receivable television wave in the carrier frequency band associated with the previously selected channel, the data for the channel is deleted in step S165, and the process returns to step S110. Thereby, the channel is not registered in the channel data table T1, and the process for the next channel is executed. If the RF-AGC voltage is greater than 3.1 V, it can be said that a television signal that cannot be reproduced properly is received because the signal strength of the intermediate frequency signal is weak. However, since it is confirmed that the synchronization signal is detected in step S120, there is a high possibility that a spurious signal derived from the original television wave is received. The spurious signal is a harmonic component derived in the broadcast path of the television radio wave, and the signal intensity is significantly attenuated as compared with the original television radio wave. Therefore, by setting an absolute threshold value for the RF-AGC voltage, it is possible to reliably exclude the spurious component of the TV radio wave from the channel registration target.

  On the other hand, if the RF-AGC voltage is 3.1 V or less, the carrier frequency is stored in the channel data table T1 in step S170. In this sense, it can be said that the microcomputer 19 corresponds to the channel storage means of the present invention. When the carrier frequency is shifted when acquiring the synchronization signal or the AFT voltage, the shifted carrier frequency is stored in association with the channel. In step S180, it is confirmed whether or not the processing has been completed for all the channels. If not, the processing returns to S100 and the processing is continued for the next channel. On the other hand, if the processing has been completed for all channels, the processing is terminated. In this way, only the channels that can be properly received are registered in the channel data table T1 after the channel registration processing is performed, and only the valid channels are selected by referring to the channel data table T1. It becomes possible to do.

(3) Summary:
As described above, in the present invention, when the RF-AGC voltage is larger than 3.1 V, it is determined that there is no receivable television wave in the carrier frequency band associated with the selected channel. In this way, by setting an absolute threshold value for the RF-AGC voltage, it is possible to reliably exclude the spurious component of the TV radio wave from the channel registration target.

It is a block block diagram of a television. It is a figure which shows a channel data table. It is a flowchart which shows the flow of a channel registration process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Television 10a ... Antenna terminal 11 ... Tuner 12 ... SAW filter 13 ... Intermediate frequency amplifier circuit 14 ... Video detection circuit 15 ... Video signal processing circuit 15a ... Sync separation circuit 16 ... AGC circuit 17 ... AFT circuit 18 ... EEPROM
19 ... Microcomputer 19e, 19f ... A / D port 30 ... Antenna

Claims (6)

In a television equipped with a channel selecting means for selecting a carrier wave of a carrier frequency corresponding to a channel to be received and generating an intermediate frequency signal from the selected television wave,
A SAW filter for adjusting the frequency characteristics of the intermediate frequency signal;
Amplifying means for acquiring an AGC voltage corresponding to the signal strength of the intermediate frequency signal and amplifying the intermediate frequency signal by an amplification factor based on the AGC voltage;
Synchronization signal detecting means for detecting a synchronization signal from the intermediate frequency signal;
A frequency correction means for detecting an AFT voltage corresponding to a frequency shift with respect to a reference frequency of the intermediate frequency signal and correcting the frequency of the intermediate frequency signal based on the AFT voltage;
A microcomputer that inputs the AGC voltage as a digital signal from the A / D port when the synchronization signal is detected and the AFT voltage is in a predetermined range;
The channel selection means is selected when the microcomputer is provided with the microcomputer, compares the input AGC voltage with a predetermined threshold value, and the comparison result indicates that the signal strength of the intermediate frequency signal is high. Determining means for determining that the TV radio wave corresponding to the carrier frequency is present;
And a channel storage unit for storing the carrier frequency determined by the determination unit in the EEPROM in association with the channel. In a television equipped with a channel selecting means for selecting a carrier wave of a carrier frequency corresponding to a channel to be received and generating an intermediate frequency signal from the selected television wave,
Amplifying means for acquiring an AGC voltage corresponding to the signal strength of the intermediate frequency signal and amplifying the intermediate frequency signal by an amplification factor based on the AGC voltage;
Determination means for determining that the television radio wave corresponding to the carrier frequency selected by the channel selection means is present when the signal strength of the intermediate frequency signal is recognized to be high based on the AGC voltage. When,
And a channel storage means for storing the carrier frequency determined to be present by the determination means in association with the channel.   3. The television according to claim 2, wherein the determination means recognizes that the signal strength of the intermediate frequency signal is high based on a comparison result between the AGC voltage and a predetermined threshold value. While having a synchronization signal detection means for detecting a synchronization signal from the intermediate frequency signal,
The determination means corresponds to the carrier frequency selected by the channel selection means when the synchronization signal is detected and the signal strength of the intermediate frequency signal is recognized to be high based on the AGC voltage. The television according to claim 2, wherein the television radio wave is determined to be present. A frequency correction means for detecting an AFT voltage corresponding to a frequency shift with respect to a reference frequency of the intermediate frequency signal and correcting the frequency of the intermediate frequency signal based on the AFT voltage;
The determination unit is configured to select the carrier selected by the channel selection unit when the AFT voltage is within a predetermined range and the signal strength of the intermediate frequency signal is recognized to be high based on the AGC voltage. 5. The television according to claim 2, wherein the television radio wave corresponding to the frequency is determined to exist.   6. The television according to claim 2, wherein the determination means is provided in a microcomputer, and the AGC voltage is input to the microcomputer as a digital signal via an A / D port.

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