JPH10233969A - Channel selection device for television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic channel preset system channel selection device that presents a broadcast channel with high reception sensitivity preferentially. SOLUTION: In the case of executing automatic channel preset, an AGC voltage is controlled so as to reduce an amplification factor for an RF signal as to all frequencies of received broadcast programs or an IF signal, and an AGC voltage when no reception broadcast station is in existence is stored to a RAM 24e. AGC voltages of a broadcast tuner stored in the RAM 24e are compared and a broadcast channel with higher reception sensitivity is stored in an EEPROM 22 as position data. A position corresponding to the channel number is preset in the case of receiving broadcast programs of 1-12 channels of a VHF band, and a broadcast channel with higher reception channel is preset to a channel position of broadcast channels for a UHF band to which broadcast programs of 1-12 channels is not preset in the order of lower frequency positions to younger number positions sequentially.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel selection device for a television receiver employing an auto channel preset system for preferentially presetting a broadcast channel having high reception sensitivity.

[0002]

2. Description of the Related Art A channel selection device incorporated in a television receiver is roughly classified into a voltage synthesizer system and a frequency synthesizer system. The voltage synthesizer type channel selection device employs a local oscillation circuit composed of a voltage-controlled oscillation circuit using, for example, a variable capacitance diode, and variably controls the local oscillation frequency according to the analog tuning voltage, but directly controls the frequency itself. Since it is not a system that uses a simple television receiver, it is often applied to a simple television receiver. On the other hand, the frequency synthesizer type tuning apparatus adopts a local oscillation circuit such as a PLL (phase locked loop) synthesizer or a direct digital synthesizer, and directly controls the local oscillation frequency by external numerical data or the like. Since a predetermined frequency is autonomously maintained by the loop, the channel selection accuracy is high, and it tends to be applied to high-end models.

[0003] Generally, a television receiver is provided with twelve channel names called channel positions. After purchasing the television receiver, the user allocates channels corresponding to each position, that is, a channel selection preset operation. In the subsequent use, it is common to receive a desired channel by inputting a channel position from a remote controller or the like. The position number, the broadcast channel number to be received, and the display number to be displayed on the screen at the time of image reception are independent of each other. For example, a broadcast signal of channel number "42" is received at position number "1", and the display number is changed. A setting of “4” is also possible. However, channel presetting in which a desired receiving channel is assigned to an arbitrary channel position and set is a considerably troublesome operation for the user.

That is, in the channel presetting of the conventional voltage synthesizer type channel selecting device, the user has to adjust the tuning voltage by himself / herself to match the frequency of the broadcast wave, and the channel preset in the conventional frequency synthesizer type channel selecting device. Is a very time-consuming operation because it is necessary to find out on which channel the user can receive the broadcast in the area where the user receives. Therefore, recent television receivers adopt an auto channel preset method in which the frequency of a broadcast wave is swept by a channel selection operation unit and the frequency of the broadcast wave is automatically preset to a plurality of channel positions in order. Things are increasing.

FIG. 5 is a schematic block diagram showing an example of a conventional voltage synthesizer type channel selecting device. FIG.
5 is a flowchart for explaining the auto channel preset operation. The voltage synthesizer type tuning apparatus 1 shown in FIG. 5 includes an EEPROM 2, a tuning operation unit 3, a tuning processing unit 4, a tuner 5, a video processing circuit 6, and the like. The tuning operation unit 3 may be basically considered to be the same as a remote control transmitter provided with a mode designation key, numeric keys of 0 to 9, or a decision key or a cancel key. In the case of this example, the number of presettable channel positions in the tuning apparatus 1 is 12, and the VHF low band (VHF-L band) and the VHF high band (VHF-H).
The tuning voltage data serving as a reference for the 12 channels included in the band is previously stored in the EEPROM 2.

When an automatic channel preset start input is made from the tuning operation section 3 to the tuning processing section 4 during the auto channel presetting, a reversible counting type data counter 4a in the tuning processing section 4 is operated. In step (102) following step (101) shown in FIG.
The tuning voltage reference data of the VHF-L1 channel is read from the PROM 2, and the count value of the data counter 4a is set to the tuning voltage reference data. The tuning voltage reference data set in the data counter 4a is converted into an analog tuning voltage signal by the D / A converter 4b and supplied to the tuner 5. Thereby, the local oscillation frequency of the tuner 5 is variably controlled to a frequency corresponding to the tuning voltage, and tuning tuning is performed. AFT obtained from the video processing circuit 6 as a result of tuning selection by the tuner 5
(Automatic fine tuning) When the tuning determination signal indicating that the voltage stabilizes to a constant voltage and a synchronization signal exceeding a predetermined threshold level is obtained is supplied to the signal determination circuit 4c, a determination step (103) )), In step (104)
The signal discriminating circuit 4c outputs the EEPRO from the data counter 4a.
The tuning voltage of channel position 1 for M2 is 1
Write the tuning voltage reference data for the channel.
However, if no broadcast is received, no data is written. Next, a loop returning from step (105), (106) to step (102) is repeatedly executed,
By performing the same operation on the VHF-L2 channel and thereafter, the tuning voltage reference data is stored in the channel position corresponding to the reception channel number up to the VHF-H12 channel.

On the other hand, broadcasting stations in the UHF band are VHF-L,
There is no broadcast in the VHF-H band, and presetting is performed to an empty channel position where presetting was not performed. First, as shown in step (107), the selected band is switched to the UHF band, and the data counter 4a starts counting up (addition counting). At this time, when the signal discriminating circuit 4c confirms that the broadcast is received by the AFT voltage and the synchronization discriminating signal from the video processing circuit 6, in a step (109) following the judging step (108), the count of the data counter 4a is counted. The up operation stops, and the data of the data counter 4a at that time is preset to the channel number with the smallest number among the non-preset channel positions of the channel positions 1 to 12. Since the data counter 4a resumes the count-up operation, the channel preset for the UHF band is continuously performed. When the tuning voltage data is written to all the presettable channel positions or when the search is completed up to the maximum tuning voltage in the UHF band, the determination steps (110) and (11)
Upon receiving the result of the determination 1), the auto channel preset operation ends.

FIG. 7 is a schematic block diagram showing an example of a conventional frequency synthesizer type channel selecting apparatus.
Is a flowchart for explaining the auto channel preset operation. This tuning device 11 also has 12 preset channel positions and is composed of an EEPROM 12, a tuning operation unit 13, a tuning processing unit 14, a tuner 15, a video processing circuit 16, and the like. The configuration of the station processing unit 14 is different from that of the voltage synthesizer system.

In auto channel presetting,
The tuning processing unit 14 that has received the auto channel preset start input from the tuning operation unit 13 performs the step (2) shown in FIG.
In 01), the count value of the channel number counter 14a is set to 1 [CH]. As a result, the following step (2)
02), the channel data storage ROM 14b
, The channel data of one channel is read out to the channel data counter 14c and supplied to the tuner 15 as the channel data. The tuner 15 which receives the supply of the channel data is directly variably controlled in the local oscillation frequency, and performs tuning tuning corresponding to the set channel data by a PLL circuit which oscillates while maintaining a predetermined frequency autonomously by a feedback loop. Signal discriminating circuit 14
d determines the reception of the broadcast based on the AFT voltage from the video processing circuit 16 and the synchronization determination signal,
03), in a step (204), the EEPRO
Information that “the reception channel at position 1 = 1CH” is written to M12. If the corresponding broadcast could not be received, no data is written. Next, in step (205), the channel number counter 1
4a is set to 2 [CH], and the second and subsequent channels are set to 12 [CH].
The same operation is repeated up to the channel. Thus, 12
Up to the channel, channel data is stored in a channel position corresponding to the reception channel number.

[0010] UHF band broadcasting stations are VHF-L, VHF.
-Preset to an empty channel position where no broadcast was performed in the H band and no preset was performed. First, the value of the channel number counter 14a is set to 13 [CH].
When the signal determination circuit 14d determines the reception of the broadcast based on the AFT voltage and the synchronization determination signal from the video processing circuit 16, the data "reception channel = 13CH" of the channel number counter 14a at that time is preset in the positions 1 to 12. Preset to the lowest numbered channel position among unused channel positions. Next, the value of the channel number counter 14a is set to 1
4 [CH] is set and the same operation is performed. When the channel number data is written to all of the presettable channel positions, or when the search is completed up to the 62th channel, the judgment result of the judgment steps (206) and (207) is received, and the auto channel preset operation ends.

[0011]

Both the conventional voltage synthesizer type tuning device 1 and the frequency synthesizer type tuning device 11 have a signal discriminating circuit 4 irrespective of the receiving sensitivity.
An auto channel preset method is used in which the 12 channel positions prepared in accordance with the determination result of c or 14d are sequentially filled, and the strength of the received signal depends on the sensitivity of the video processing circuits 6 and 16 for the synchronization determination. A broadcast channel that is weak and unsuitable for viewing may be determined to have a synchronization signal and may be preset. In such a case, although the number of broadcast stations with good reception conditions is smaller than the presettable channel positions, a large number of broadcast stations that are not suitable for viewing are preset in the initial stage of the sweep channel selection, and are more likely to be performed in higher frequency bands. There has been a problem that a broadcast channel having good reception sensitivity may not be preset. On the other hand, even when the number of broadcast channels determined to be broadcast is larger than the number of channel positions that can be preset by the auto channel preset, a broadcast channel with higher reception sensitivity can be received in a high frequency band of the UHF band. Nevertheless, before sweeping and selecting the reception band of the broadcast channel, presetting to all channel positions is performed, and as a result, there is a problem that a broadcast channel with high reception sensitivity cannot be received. there were.

The present invention has been made to solve the above-mentioned problems, and employs an auto channel preset method of preferentially presetting a broadcasting station having a strong received signal strength so that a broadcasting station suitable for viewing can be surely preset. It is intended to do so.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a tuner for sweeping a tuning voltage or a tuning frequency over the entire receiving band of a television wave, and the sweeping process of the tuner. A memory for storing the automatic gain control voltage at the tuning point obtained in the above as the reception sensitivity of the selected broadcast channel, and a broadcast channel having a high reception sensitivity stored in the memory is preferentially selected, and a finite number of Means for allocating to a channel position and presetting a channel.

Further, according to the present invention, the tuning means includes a voltage synthesizer type tuner which performs a tuning operation by designating a tuning voltage, or the tuning means designates a tuning operation by designating a tuning frequency. And the like.

Further, the channel presetting means preferentially presets the channel position corresponding to the channel number of the received broadcast channel for the VHF band broadcast, and the channel position among the channel positions for the UHF band broadcast. In the vacant channel positions where the VHF broadcast channels are not preset, the number of vacant channel positions is selected in descending order of reception sensitivity among the received broadcast channels, and the selected broadcast channels are numbered in ascending order from the lowest frequency. Is preset to the channel position number of

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic block diagram showing an embodiment in which a channel selection device of a television receiver according to the present invention is applied to a voltage synthesizer system. FIG. 2 is an automatic channel preset by the channel selection device shown in FIG. It is a flowchart for explaining operation. FIG. 3 is a schematic block diagram showing an embodiment in which the channel selection device of the television receiver of the present invention is applied to a frequency synthesizer system. FIG. 4 is an automatic block diagram of the channel selection device shown in FIG. 5 is a flowchart for explaining a channel preset operation.

The tuning device 21 shown in FIG. 1 is of a voltage synthesizer type, and includes an AGC voltage control circuit 27, an EEPROM 22, a tuning operation unit 23, a tuning processing unit 24, a tuner 25, and a video processing circuit 26. A D / A converter 28 is provided. The EEPROM 22 is an electrically erasable non-volatile memory, is connected to the channel selection processing unit 24, and stores the correspondence between the channel position preset by the auto channel preset and the tuning voltage reference data. Tuning operation section 23
Here, the remote control transmitter is provided with a mode designating key, numeric keys of 0 to 9, or an enter key and a cancel key.

The tuning section 24 includes a data counter 24a.
, A D / A converter 24b, an AGC control counter 24c, a signal discriminating circuit 24d, and a RAM 24e.
The substance is a microprocessor system, and an auto channel preset operation described later is executed according to preset software. Data counter 2
In 4a, the tuning voltage reference data is set as a count value in response to an auto channel preset input given from the tuning operation unit 23, and counts up (addition counting) in response to confirmation of a broadcast channel. D / A converter 2
4b converts the count output of the data counter 24a into an analog tuning voltage signal and supplies it to the tuner 25. AG
The C control counter 24c operates in response to the discrimination output of the signal discrimination circuit 24d, adds or subtracts the AGC control voltage so that the amplification factor of the RF signal or the IF signal becomes low, and modulates the counting result by pulse width modulation (PWM). ) D /
The signal is supplied to the A converter 28. The signal discrimination circuit 24d includes an AF
A tuning discrimination signal indicating that a T (automatic fine tuning) voltage and a synchronizing signal exceeding a predetermined threshold level have been obtained is supplied from the video processing circuit 26, and the tuning is confirmed and the data counter 24a and the AGC control counter 24c are counted. Orders addition or subtraction of numbers. The RAM 24d has a data counter 24
a and each count value at the time when the AGC control counter 24c stops counting, that is, at the synchronization point, is supplied, and both count values are stored as a set of data.

The tuner 25 changes the local oscillation frequency in accordance with the tuning voltage supplied from the channel selection processing unit 24,
The gain is variably controlled according to the AGC voltage supplied from the GC voltage control circuit 27. I obtained from tuner 25
The F signal is supplied to the video processing circuit 26. The video processing circuit 26 is, for example, a chroma IC or the like, performs luminance signal processing and color signal processing on the IF signal supplied from the tuner 25, and supplies a color difference signal or a primary color signal to a video output circuit (not shown). Further, the video processing circuit 26 has a built-in AGC (automatic gain control) circuit for variably controlling the gain (amplification factor) of the IF signal, and supplies the AGC voltage control circuit 27 with an AGC voltage that makes the IF signal a constant amplitude. Supply.
The AGC voltage control circuit 27 increases or decreases the AGC voltage supplied from the video processing circuit 26 in accordance with the DC voltage signal supplied from the D / A converter 28, and in the present embodiment, the UHF band In order to discriminate the level of the AGC voltage for each broadcast channel received in the step (1), a tuned state and an untuned state are intentionally formed.

The number of presettable positions prepared in the channel selection device 21 is 12 positions, and VHF-L,
It is assumed that a tuning voltage serving as a reference is previously stored in the EEPROM 22 for the 12 channels of the VHF-H band. At the time of the auto channel preset, first, the tuning voltage reference data of the VHF-L1 channel is read from the EEPROM 22 in response to the auto channel preset start input from the tuning operation section 23, and the step (3) following the step (301) shown in FIG.
In 02), the value of the data counter 24a is set to the tuning voltage reference data. Data counter 24a
The tuning voltage reference data output by the tuner 2 is converted into an analog signal by the D / A converter
5 is supplied. Note that the initial value of the AGC voltage control circuit 27 at this time is a value that does not apply any control to the AGC voltage.

The signal discriminating circuit 24d includes a video processing circuit 26
It is determined whether or not the broadcast station has been received based on the AFT voltage and the synchronization determination signal from the CPU. If it is determined that the broadcast station has been received, the position is stored in the EEPROM 22 in a step (304) following the determination step (303). 1
The tuning voltage reference data of one channel is written as the tuning voltage of. If no broadcast station is received, E
Data writing to the EPROM 22 is not performed. Next, in step (305), VHF-L2
The tuning voltage reference data of the channel is EEPRO
M22, the value of the data counter 24a is set to the tuning voltage reference data, and the determination step (30)
Until the determination in 6) is affirmed, the same operation is performed from the VHF-L2 channel to the 12th channel. For this reason, up to the VHF-HI2 channel, the tuning voltage reference data is stored at a position corresponding to the reception channel number.

The broadcast channel of the UHF band is VHF-
There is no broadcasting station in the L, VHF-H band and presetting is performed to an empty channel position where presetting was not performed. First, after switching the tuning band to the UHF band in step (307), the counting up of the count value of the data counter 24a is started. In this case, the initial value of the AGC control counter 24c is a value that does not control the AGC voltage. The signal discrimination circuit 24d receives the AF signal from the video processing circuit 26.
When it is confirmed that the broadcast station has been received by the T voltage and the synchronization determination signal, the count value of the data counter 24a at that time is stored in the RAM 24e of the channel selection processing unit 24 at the time.

Next, the count value of the data counter 24a is set to the value R
In step (309), the count value of the AGC control counter 24c is counted up (addition count) or countdown (subtraction count) so that the amplification factor of the F signal or the IF signal becomes low. At this time, A
The data of the GC control counter 24c is output as a PWM signal, and is converted by the D / A converter 28 into a DC voltage signal proportional to the duty ratio of the PWM signal. The output from the D / A converter 28 is input to the AGC voltage control circuit 27,
D / D so that the amplification factor of the RF signal or IF signal is low.
The AGC voltage increases or decreases in proportion to the input voltage from the A converter 28. Thus, AGC control counter 2
By continuing the count-up (addition count) or count-down (subtraction count) of 4c, the IF signal supplied from the tuner 25 to the video processing circuit 26 gradually attenuates. The AGC control counter 24c stops counting up or counting down when the signal determination circuit 24d determines that there is no receiving broadcast station based on the synchronization determination signal from the video processing circuit 26.

The count value of the AGC control counter 24c at the time when the counting is stopped is combined with the channel position to form a set of data. In a step (311) following the determination step (310), the RAM 24 in the channel selection operation section 23
e. In this case, the AGC control counter 24c
Indicates the amount of increase or decrease of the AGC voltage when changed from the state with synchronization to the state without synchronization. Next, steps (308) to (311) are repeated until the sweep is completed. That is, the count value of the AGC control counter 24c is returned to the initial value in which nothing is controlled with respect to the AGC voltage, the counting up is stopped, and the counting up of the data counter 24a is restarted from the held value. Hereinafter, the same operation is performed for all the broadcast channels in the UHF band, and for the signal determined to have the broadcast channel in the UHF band, the amount of increase or decrease in the AGC voltage changed from the state of synchronization to the state of no synchronization is indicated by AGC. The count value of the control counter 24c is stored in the RAM 24e. Thus, when the sweep is completed, the comparison of the count value of the AGC control counter 24c indicates that A
It is possible to relatively know the strength of the received signal without controlling the GC voltage. In other words, the larger the amount of change from the initial value of the AGC control counter 24c, the greater the amount of control of the AGC voltage from synchronization to non-synchronization, indicating higher reception sensitivity.

For this reason, in a step (313) following the determination step (312), the count value of the AGC control counter 24c of the UHF broadcast channel stored in the RAM 24e is compared, and the broadcast channel having the higher receiving sensitivity is shifted to the empty channel position. Select only the number. Further, in the following step (314), the selected broadcast channels are arranged in order from the lowest frequency, and correspond to the channel position number of the younger number.
Store it in 2. For this reason, for example, when one broadcasting station operation receives five broadcasting stations in the VHF-L and VHF-H bands and fifteen stations in the UHF band, a total of 20 broadcasting channels are received, the channel selecting device 21 has only 12 positions. Since presetting is not possible, in the VHF-L and VHF-H bands, a broadcasting channel having a channel number corresponding to the position number is preset, and then in the UHF band, seven broadcasting channels are selected in descending order of reception sensitivity, and EEPRO is selected.
It is stored as position data in M22. At this time, the seven broadcast channels with high reception sensitivity are preset from the lowest numbered position in the order of lower frequency.

As described above, according to the channel selection device 21,
In the reception environment where the number of broadcast channels judged to be broadcast is larger than the number of channel positions that can be preset at the time of auto channel presetting, or a higher quality broadcast is received in a high frequency band of the UHF band. Even in a simple reception environment, the tuning voltage is swept in the UHF band of the television signal to preset the higher-sensitivity broadcast channel preferentially, so all channel positions are preset before sweeping the entire reception band. There is no presetting of broadcast channels that are not suitable for viewing due to weak received radio waves or UH suitable for viewing with high reception sensitivity.
It is possible to reliably preset the F broadcast channel.

The tuner 21 is a tuner 2 of a voltage synthesizer system which performs a tuning operation by designating a tuning voltage.
5, a local oscillation circuit composed of a voltage-controlled oscillation circuit using a variable capacitance diode or the like is employed, and the local oscillation frequency is variably controlled in accordance with the analog tuning voltage, so that the broadcast corresponding to the tuning voltage is performed. Channels can be tuned, and a low cost structure can be obtained by taking advantage of the low cost burden characteristic of such a voltage synthesizer system.

In the above embodiment, the level of the receiving sensitivity is reflected in the preset only in the UHF band. However, the receiving sensitivity is stored in the RAM 24e for the broadcast channel in the VHF band, and the receiving sensitivity is stored in the entire band. It is also possible to adopt a configuration in which presetting is performed with priority given to sensitivity. When a broadcast channel discriminating signal is superimposed on a television signal, the broadcast channel discriminating signal is decoded, and when a plurality of same broadcast channels are detected, the signal having the highest reception sensitivity among them is detected. It is also possible to preset only high broadcast channels.

The present invention is not limited to the voltage synthesizer type channel selecting device 21, but can also be applied to a frequency synthesizer type channel selecting device. The tuning device 31 shown in FIG.
The frequency synthesizer system is used, and the number of positions that can be preset is 12 positions. Tuning device 31
Is different from the tuning apparatus 21 in the configuration of the tuning processing unit 34 and the tuner 35, but the other configuration is the same as that of the above-described twentieth unit except that the suffix code of the twentieth unit is the same. It has the same configuration as the tuning device 21. Specifically, a channel data counter 34b and a ROM 34f for storing channel data are connected to a channel number counter 34a in the channel selection processing unit 34, and the output of the ROM 34f for storing channel data is output from the channel data counter 34b.
It is supplied to. The channel data storage ROM 34f stores channel data that defines a tuning frequency for each broadcast channel, and the channel data read from the channel data storage ROM 34f is given to the channel data counter 34b.

Here, by starting the auto channel preset from the channel selection operation section 33, the step (40) shown in FIG.
In 1), the value of the channel number counter 34a is set to 1
Set to [CH]. This allows the following step (40)
In 2), channel data of one channel is read from the channel data storage ROM 34f to the channel data counter 34b and supplied to the tuner 35 as channel data. When the signal determination circuit 34d determines that the broadcast station has been received based on the AFT voltage and the synchronization determination signal from the video processing circuit 36, the determination step (4)
03), in a step (404), the EEPRO
Information that “the reception channel at position 1 = 1CH” is written to M32. If there is no broadcast station reception,
No data is written. Next, step (40)
In 5), the value of the channel number counter 34a is set to 2
[CH], and the same operation is performed for the second to 12th channels until the determination in the determination step (406) is affirmed. Thus, up to 12 channels are stored in the channel position corresponding to the reception channel number.

The broadcasting stations in the UHF band are VHF-L, VHF
-Preset to a position where there was no broadcasting station in the H band and no preset was performed. First, in step (407), the value of the channel number counter 34a is set to 13 [C
H]. However, the initial value of the AGC control counter 34c is a value that does not control anything with respect to the AGC voltage. The signal discrimination circuit 34d receives the AF signal from the video processing circuit 36.
When it is confirmed that the broadcast station has been received based on the T voltage and the synchronization determination signal, the data of the channel number counter 34a at that time is stored in the RAM 34e of the channel selection processing unit 34 at that time.

Next, in step (409), while holding the channel number counter 34a and the channel data counter 34b, the count value of the AGC control counter 34c is counted up so that the amplification factor of the RF signal or the IF signal becomes low. (Addition count) or countdown (subtraction count). The data of the AGC control counter 34c is output from the tuning operation unit 33 as a PWM signal.
The / A converter 38 converts the PWM signal into a DC voltage signal proportional to the duty ratio. The output of the D / A converter 38 is supplied to the AGC voltage control circuit 37, and the AGC voltage is controlled in proportion to the input voltage from the D / A converter 38 so that the amplification factor of the RF signal or the IF signal is reduced. Increase or decrease. Thus, the IF signal supplied from the tuner 35 to the video processing circuit 36 is gradually attenuated by continuing the count-up (addition counting) or count-down (subtraction counting) of the AGC control counter 34c. When the signal determination circuit 34d determines that there is no received broadcast channel based on the synchronization determination signal, A
Counting up (addition counting) of the GC control counter 34c
Alternatively, the countdown (subtraction counting) stops.

The count value of the AGC control counter 34c at the time when the counting is stopped is combined with the data of the channel number counter 34a to form a set of data.
0), in the step (411), the channel selection processing unit 3
4 is stored in the RAM 34e. In this case, the count value of the AGC control counter 34c indicates the amount of increase or decrease of the AGC voltage changed from the state with synchronization to the state without synchronization. Next, the count value of the AGC control counter 34c is set to AG
The value is returned to the initial value in which no control is performed on the C voltage, and the value of the channel number counter 34a is set to 14 [CH].
By performing the same operation up to 62 channels, 13
For the channels determined to have a broadcast station in channels # 62 to # 62, the amount of increase or decrease of the AGC voltage changed from the state with synchronization to the state without synchronization is represented by A
It can be stored as the count value of the GC control counter 34c. Thus, when the sweep is completed, it is possible to relatively know the strength of the received signal without controlling the AGC voltage from the comparison of the count values of the AGC control counter 34c. That is, the larger the amount of change from the initial value of the AGC control counter 34c, the greater the amount of control of the AGC voltage from synchronization to non-synchronization, indicating higher reception sensitivity.

For this reason, in a step (414) following the judgment step (413), the count value of the AGC control counter 34c of the UHF broadcast channel stored in the RAM 34e is compared, and the broadcast channel having the higher reception sensitivity is shifted to the vacant channel position. Select only the number. Further, in the following step (415), the selected broadcast channels are arranged in order from the lowest frequency, and correspond to the channel position number of the younger number.
Store it in 2. For this reason, for example, when a total of 20 broadcasting channels of 5 stations in the VHF-L and VHF-H bands and 15 stations in the UHF band are received by one round channel selection operation, the channel selecting device 31 has only 12 positions. Since presetting is not possible, in the VHF-L and VHF-H bands, a broadcasting channel having a channel number corresponding to the position number is preset, and then in the UHF band, seven broadcasting channels are selected in descending order of reception sensitivity, and EEPRO is selected.
It is stored as position data in M32. At this time, the seven broadcast channels with high reception sensitivity are preset from the lowest numbered position in the order of lower frequency.

As described above, according to the channel selection device 31,
In the reception environment where the number of broadcast channels judged to be broadcast is larger than the number of channel positions that can be preset at the time of auto channel presetting, or a higher quality broadcast is received in a high frequency band of the UHF band. Even in a simple reception environment, since the tuning frequency is swept over the entire UHF band and the broadcast channel with higher reception sensitivity is preferentially preset, all channel positions are preset before sweeping the entire reception band. A broadcast channel that is not suitable for viewing due to the strength of the received radio wave being weak or being received is not preset, and a broadcast channel having high reception sensitivity and suitable for viewing can be surely preset. In addition, the tuning device 3
Reference numeral 1 denotes a frequency synthesizer tuner that performs a tuning operation by designating a tuning frequency. Therefore, the local oscillation frequency is directly controlled by external numerical data or the like, and the oscillation is performed while maintaining a predetermined frequency autonomously by a feedback loop. The channel can be selected and the desired channel can be selected immediately.Therefore, some cost burden must be prepared compared to the voltage synthesizer method, but the accuracy of the channel selection preset is improved to ensure the accuracy. Presets are possible.

In the above embodiment, the level of the reception sensitivity is reflected in the preset only in the UHF band. However, the reception sensitivity is stored in the RAM 24e for the broadcast channel in the VHF band, and the reception is performed in the entire band. It is also possible to adopt a configuration in which presetting is performed with priority given to sensitivity.

[0038]

As described above, according to the present invention,
The automatic gain control voltage at the tuning point obtained in the sweeping process of the tuning means for sweeping the tuning voltage or tuning medium wave number over the entire receiving band of the television wave is stored as the reception sensitivity of the selected broadcast channel. , And the broadcast channels with high reception sensitivity stored in this memory are preferentially assigned to a finite number of channel positions to perform channel presetting. Even in a reception environment in which the number of broadcast channels judged to be broadcasted is larger, or in a reception environment in which higher quality broadcasting is received in a high frequency band of the UHF band, the entire reception band of the television wave is Sweeps the tuning voltage or tuning frequency over the Since the presetting is performed first, all channel positions are preset before sweeping the entire receiving band, or the broadcast channel that is not suitable for viewing due to weak received radio wave is not preset. A broadcast channel having high sensitivity and suitable for viewing can be reliably preset. Further, if a broadcast channel discrimination signal is superimposed on a television signal, the broadcast channel discrimination signal is decoded and the broadcast channel discrimination signal is decoded. When a plurality of broadcast channels are detected, there is an excellent effect that it is possible to preset only the broadcast channel having the highest reception sensitivity among them.

Further, since the tuning means is a voltage synthesizer type tuner which performs a tuning operation by designating a tuning voltage, for example, a local oscillation circuit comprising a voltage controlled oscillation circuit using a variable capacitance diode or the like is employed, By variably controlling the local oscillation frequency according to the tuning voltage, a broadcast channel can be selected in accordance with the tuning voltage.
By taking advantage of the low cost burden, which is a feature of such a voltage synthesizer system, it is possible to achieve effects such as a low-cost configuration.

Further, since the tuning means is a frequency synthesizer tuner which performs a tuning operation by designating a tuning frequency, a local oscillation circuit such as a PLL synthesizer or a direct digital synthesizer is employed, and numerical data such as numerical data is externally provided. The local oscillation frequency can be controlled directly by using a feedback loop to oscillate while maintaining the predetermined frequency autonomously, and the desired channel can be selected immediately with the designation of the channel number. Although it is necessary to prepare for the cost, there is an effect that the accuracy of the channel selection preset is improved and a reliable preset can be performed.

Further, the channel presetting means preferentially presets the channel position corresponding to the channel number of the received broadcast channel for the VHF band broadcast, and the channel position among the channel positions for the UHF band broadcast. In the vacant channel positions where the VHF broadcast channels are not preset, the number of vacant channel positions is selected in descending order of reception sensitivity among the received broadcast channels, and the selected broadcast channels are numbered in ascending order from the lowest frequency. In order to preset to the channel position number of the VHF band, a channel position is given to a broadcast channel received with a certain reception sensitivity among the broadcast channels of the VHF band, and then a certain reception sensitivity of the broadcast channels of the UHF band is given. By providing a free channel position to the received broadcast channels, the effects of the like can be effectively used a finite number channel position.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an embodiment when a channel selection device of a television receiver of the present invention is applied to a voltage synthesizer system.

FIG. 2 is a flowchart for explaining an auto channel preset operation by the tuning apparatus shown in FIG. 1;

FIG. 3 is a schematic block diagram showing an embodiment in which the tuning device of the television receiver of the present invention is applied to a frequency synthesizer system.

FIG. 4 is a flowchart for explaining an auto channel preset operation by the channel selection device shown in FIG. 3;

FIG. 5 is a schematic block diagram illustrating an example of a conventional voltage synthesizer type channel selection device for a television receiver.

FIG. 6 is a flowchart for explaining an auto channel preset operation by the channel selection device shown in FIG. 5;

FIG. 7 is a schematic block diagram showing an example of a conventional frequency synthesizer type channel selection device for a television receiver.

FIG. 8 is a flowchart for explaining an auto channel preset operation by the tuning apparatus shown in FIG. 7;

[Explanation of symbols]

21, 31 Tuning device 22, 32 EEPROM 23, 33 Tuning operation unit 24, 34 Auto channel presetting means (Tuning processing unit) 24a Data counter 24b D / A converter 24c AGC control counter 24d Signal processing circuit 24e Memory ( RAM) 25 Tuning means (voltage synthesizer tuner) 26 Video processing circuit 27 AGC voltage control circuit 28 D / A converter 34a Channel number counter 34b Channel data counter 34c AGC control counter 34d Signal discriminating circuit 34e Memory (RAM) 34f channel Data storage ROM 35 Tuning means (frequency synthesizer tuner)

Claims (4)

[Claims] 1. Tuning means for sweeping a tuning voltage or tuning frequency over the entire receiving band of a television wave, and tuning an automatic gain control voltage at a tuning point obtained in the sweeping process of the tuner. A memory for storing the reception sensitivities of the selected broadcast channels, and a means for preferentially selecting the broadcast channels with high reception sensitivities stored in the memory and assigning them to a finite number of channel positions for channel presetting. Characteristic selection device for television receiver. 2. The apparatus according to claim 1, wherein said tuning means includes a voltage synthesizer tuner for performing a tuning operation by specifying a tuning voltage. 3. The tuning apparatus for a television receiver according to claim 1, wherein said tuning means includes a frequency synthesizer tuner which performs a tuning operation by designating a tuning frequency. 4. The apparatus according to claim 1, wherein said channel preset means comprises a VH
For F-band broadcasting, presetting is performed preferentially at the channel position corresponding to the channel number of the received broadcasting channel. For UHF-band broadcasting, the VHF broadcasting channel is set to an empty channel position where the VHF broadcasting channel was not preset. Selecting the number of available channel positions in descending order of reception sensitivity among the received broadcast channels, and presetting the selected broadcast channels to channel number numbers of lower numbers in order of decreasing frequency. A channel selection device for a television receiver according to claim 1.