KR950014579B1 - Television channel selection apparatus - Google Patents

Abstract

The AFT (automatic frequency tuning) of second tuner in multi-tuner TV or video is adjusted by using an AFT signal of the first tuner. The apparatus includes a distributer(22) for distributing broadcasting signal received by an antenna to tuners, a first tuner(23) for tuning channel according to control signal transmitted from a microcomputer(23) and for detecting AFT signal and horizontal sync. signal, a second tuner(24) for tuning channels according control signal transmitted from a microcomputer(21), and a microcomputer(21) for generating AFT control signal.

Description

TV broadcasting signal tuning device

1 is a circuit diagram showing the configuration of a conventional one-tuner tuning device.

2 is a waveform diagram showing a characteristic curve of the AFT signal of FIG.

3 is an explanatory diagram showing an AFT control region in one channel region.

4 is a circuit diagram showing the configuration of a conventional two-tuner tuning device.

5 is a circuit diagram showing the configuration of a two-tuner tuner of the present invention.

6 is a signal flow diagram showing the operation of the microcomputer according to the present invention.

* Explanation of symbols for main parts of the drawings

21: Micom 22: Splitter

23: first station part 24: second station part

ANT21: Antenna AFT21: AFT Signal

HS21: Horizontal Sync Signal

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a television broadcast signal tuning apparatus for tuning television broadcast signals in equipment such as a television receiver and a video cassette recorder having two tuner sections with a picture in picture (PIP) function, in particular one tuner section. The present invention relates to a tuning device for a television vision broadcast signal which enables the AFT adjustment of the tuner unit and the other tuner unit to be performed using an output aft (Automatic Frequency Tunning) signal.

In the conventional one tuner tuning device having only one tuner unit, as shown in FIG. 1, the microcomputer 1 performs the AFT adjustment and controls the tuning of the broadcast signal, and the received signal of the antenna ANT1. A tuner unit 2 for tuning the broadcast signal of the selected channel under the control of the microcomputer 1, a filter 3 for removing a noise signal from the broadcast signal tuned by the tuner unit 2, and the filter; Intermediate frequency processing and outputting the output signal of (3), and a signal for processing and outputting the output signal of the intermediate frequency processor (4) and the intermediate frequency processor (4) for outputting the AFT signal to the microcomputer (1). A processing unit 5 and a horizontal synchronizing signal detection unit 6 which detects a horizontal synchronizing signal HS to the output signal of the signal processing unit 5 and inputs it to the microcomputer 1.

In this tuner type tuner, the microcomputer 1 outputs the tuning data according to the channel selected by the user, and the tuner unit 2 outputs the broadcasting signal of the channel selected from the reception signals of the antenna ANT1 according to the tuning data. Tuning is done and output.

The broadcast signal output from the tuner unit 2 is removed from the noise signal through the filter 3, is processed by the intermediate frequency processing unit 4, and is input to the microcomputer 1 where the AFT signal is detected. The output signal of the processing section 4 is processed by the signal processing section 5, and the horizontal synchronizing signal detection section 6 detects the horizontal synchronizing signal HS and inputs it to the microcomputer 1.

The microcomputer 1 first outputs the preset tuning data to the tuner 2 when selecting and changing a predetermined channel, and is required until the tuner 2 tunes the broadcast signal of the predetermined channel according to the tuning data. After delaying a predetermined time, it is determined whether the horizontal synchronous signal HS is input from the horizontal synchronous signal detection unit 6, and when the horizontal synchronous signal HS is input, it is determined that the tuning operation of the tuner 2 is completed. Then, the intermediate note performs AFT adjustment at the level of the AFT signal input from the processing unit 4.

Here, as shown in FIG. 2, the AFT signal has a characteristic in which the level changes with an S-shaped curve as the frequency changes, and the microcomputer 1 compares the level of the input AFT signal with the AFT center voltage level. The difference is determined, and the AFT adjustment is performed so that the tuning data is varied according to the level difference so that the level of the AFT signal becomes the AFT center voltage level. (Usually, AFT adjustment is based on the AFT center voltage level, and the AFT adjustment area of a certain level is set, and it is within the AFT adjustment area set by the AFT voltage and it is determined that AFT adjustment is completed.)

When the AFT adjustment is completed, the current tuning data is stored so that the next time the next channel is tuned again, the AFT tuned broadcast signal can be tuned in a short time. Calculate the deviation and store the calculated deviation data and calculate and output the tuning data with the deviation data and the center frequency data of the channel when selecting the next channel.

When the horizontal synchronization signal HS is not input, the microcomputer 1 performs a search operation to tune the broadcast signal of the selected channel.

The search operation is performed by dividing the 6MHz band, which is the frequency band of one channel, into the search area. As shown in FIG. 3, the first search area of f ₀ ± 1MHz based on the center frequency f ₀ , and ( f ₀ -1.5) divided into a second search region of ± 1 MHz and a third search region of (f ₀ +15) ± 1 MHz, and when tuning a broadcast signal of a predetermined channel, when outputting the channel selection data corresponding to _0, and not the horizontal synchronizing signal is input by the channel selection data corresponding to f ₀ is to vary the channel selection data in the first search area and performs the search operation, within the first search area If the horizontal synchronization signal is not input even after completing the search operation, the search operation is performed in the second search area and the third search area, and the horizontal synchronization is continued even if the search operation is performed up to the third search area. If no signal is input Determined to not have songsinho channel, the channel selection operation is stopped.

The conventional two-tuner tuning device employing such a one-tuner tuning device has a microcomputer 11 for performing AFT adjustment and controlling the tuning of broadcast signals, as shown in FIG. 4, and an antenna ANT11. A splitter 12 for distributing received signals and a broadcast signal selected according to the control of the microcomputer 11 from the output signal of the splitter 12 are tuned and output, and the AFT signals AFT11 and AFT12 are horizontal. Tuner sections 13A and 14A, filters 13B and 14B, intermediate frequency processing sections 13C and 14C, and signal processing section 13D for detecting the synchronization signals HS11 and HS12 and inputting them to the microcomputer 11. And a first tuning unit 13 and a second tuning unit 14 constituted by 14D and the horizontal synchronization signal detection unit 13E and 14E.

In the conventional two-tuner tuning device configured as described above, the divider 12 distributes the received signal of the antenna ANT11 to the first channel selection unit 13 and the second channel selection unit 14.

In this state, when a predetermined channel is selected and changed, the microcomputer 11 outputs tuning data corresponding to the predetermined channel, so that the tuner sections 13A and 14A of the first and second tuning sections 13 and 14 are used. Is applied to.

Then, similar to the one-tuner tuning device described above, the tuner sections 13A and 14A of the first and second tuning units 13 and 14 tune the broadcast signals of the channels according to the input tuning data, and the tuned stations are tuned. The signal is processed and output through the filters 13B and 14B, and is processed and output by the intermediate frequency processing unit 13C and 14C, and an AFT signal AFT11 or AFT12 is detected and input to the microcomputer 11 to process the intermediate note. The output signals of the integrated integrated devices 13C and 14C are processed by the signal processing units 13D and 14D, and the horizontal synchronizing signal detection units 13E and 14E detect the horizontal synchronizing signals HS11 and HS12. A horizontal synchronization signal (HS11) (HS12) inputted to (11), and the microcom (11) is inputted, breaks the tuning of the broadcast signal, and the first and second channel selection units at the level of the AFT signal (AFT11) (AFT12). (13) (14) perform AFT adjustment.

However, in the conventional two-tuner tuning device as described above, when the first and second tuning stations tune the broadcast signal of the same channel, the microcomputer performs the AFT adjustment despite the same tuning data after the AFT adjustment is completed. The tuning data of the first and second tuning stations must be stored separately, which increases the capacity of the built-in memory and adds to the load of the microcomputer, and outputs the AFT signals respectively output by the first and second tuning stations. In addition to the use of expensive microcomputers with two analog / digital converters for converting them into digital signals, the tank circuit and horizontal synchronous signals for detecting AFT signals in the intermediate frequency processing section of the first and second stations, respectively. It must be equipped with a separate horizontal synchronous signal detection unit to detect the There was a problem such that the production cost of.

The present invention has been devised to solve the above-mentioned problems, and tunes a broadcast signal by AFT adjustment of only one of the two tuning units, and stores AFT-tuned tuning data and stores another tuning station. When tuning a broadcast signal of an additional predetermined channel, there is a purpose of providing a tuning device that performs tuning by using the stored tuning data without performing AFT adjustment. FIG. 5 and FIG. It demonstrates in detail with reference.

5 is a circuit diagram showing the configuration of a two-tuner tuning device according to the present invention. As shown therein, the microcomputer 21 controls the tuning of a broadcast signal and performs AFT adjustment of the broadcast signal, and the antenna ANT21. A divider 22 for distributing the received signal of the tuner, and a broadcast signal of a channel according to the tuned data outputted by the microcomputer 21 from the output signal of the divider 22 to be tuned and outputted, together with the AFT signal AFT21 and A tuner unit 23A, a filter 23B, an intermediate frequency processor 23C, a signal processor 23D, and a horizontal synchronous signal detector 23E for detecting and inputting a horizontal synchronization signal HS21 to the microcomputer 21. A tuner unit 24A, a filter 24B, which tunes and outputs a broadcast signal of a channel corresponding to the channeling data output from the microcomputer 21 from the first channeling unit 23 and the output signal of the distributor 22; A second channel selection section 24 composed of the intermediate frequency processing section 24C and the signal processing section 24D is provided.

In the tuning device of the present invention configured as described above, the divider 22 divides the broadcast signal received by the antenna ANT21 into two, and inputs the received signal to the first channel selection unit 23 and the second channel selection unit 24, respectively.

In this state, when the first channel selection unit 23 tunes a broadcast signal of a predetermined channel according to a user's command, the first channel selection unit 23 outputs preset data corresponding to a predetermined channel to be tuned among a plurality of preset data stored in advance. It is input to the tuner part 23A of the 1st selection part 23. FIG. Then, the first channel selection unit 23 tunes and outputs the broadcast signal of the channel according to the channel data from the output signal of the splitter 22, and tunes the channel 23 to the tuner unit 23A. The noise signal is removed through the intermediate frequency processing unit 23C, and the intermediate frequency is processed and output. The AFT signal AFT21 is detected and input to the microcomputer 21. The output signal of the intermediate frequency processing unit 23C is a signal processing unit. Processed and outputted at 23D, the horizontal synchronizing signal detection unit 23E detects the horizontal synchronizing signal HS21 and inputs it to the microcomputer 21.

Then, the microcomputer 21 performs the AFT adjustment with the input horizontal synchronization signal HS21 and the AFT signal AFT21, and when the AFT adjustment is completed, the tuning data and the current tuning data currently output to the first station 23 are present. The center frequency data of the channel to be tuned is calculated and the AFT deviation data of the current channel is calculated and stored in the memory, and this operation is repeatedly performed whenever the first channel unit 23 changes the channel to be tuned. Save all AFT deviation data.

On the other hand, when the user commands the channel selection of the second channel selection unit 24, the microcomputer 21 uses the AFT deviation data for each channel of the first channel selection unit 23 stored in the memory. Control broadcasting channel selection.

That is, when the user commands the channel change of the second channel selection unit 24, the microcomputer 21 determines the channel change of the second channel selection unit 24 as shown in FIG. The AFT deviation data corresponding to the channel to be tuned by the second channel selection unit 24 is read from among a plurality of AFT deviation data of the first channel selection unit 23 stored in the AFT deviation data and the center frequency data of the channel to be tuned. Calculate the tuning data and calculate the tuning data and output the tuning data to the second channel selection unit 24.

Then, the second channel selection unit 24 tunes and outputs the broadcast signal of the predetermined channel according to the channel selection data by the tuner unit 24A according to the channel tuning data output from the microcomputer 21. One broadcast signal is removed through the filter 24B, the noise signal is removed, the intermediate frequency processing section 24C is processed by the intermediate frequency output, and the intermediate frequency processing section 23C output signal is processed and output by the signal processing section 23D.

In this way, the broadcast signals outputted by the first and second channel selection units 23 and 24 respectively tune to the PIP screen, and are output as processed signals. The output signal of the first channel selection unit 23 is used as the mother screen signal. The output signal of the channel selection unit 24 can be used as the sub picture signal, and in contrast to the above, the output signal of the first channel selection unit 23 is used as the sub picture signal, and the output of the second channel selection unit 24 is used. You can also use the signal as the parent screen signal.

As described in detail above, the present invention performs AFT adjustment on only one of the two tuning units provided for the PIP picture processing, and the other tuning unit uses the tuning data of the tuning station that performed the AFT adjustment. By tuning the broadcast signal of a predetermined channel, the capacity of the memory embedded in the microcomputer may be reduced, the load on the microcomputer may be reduced, and an analog / digital converter may be provided, so that a relatively inexpensive microcomputer may be used as well as the circuit configuration. This simple, fewer parts are required to reduce the production cost of the product.

Claims (3)

The microcomputer 21 controls the tuning of the broadcast signal and performs AFT adjustment of the broadcast signal to be tuned, a divider 22 for distributing the received signal of the antenna ANT21, and the micom in the output signal of the divider 22. A first channel selection unit 23 for tuning and outputting a broadcast signal of a channel according to the channel selection data output by the channel 21 and detecting and inputting the AFT signal AFT21 and the horizontal synchronization signal HS21 to the microcomputer 21; And a second tuning unit 24 which tunes and outputs a broadcast signal of a channel according to tuning data of the micom 21 from the output signal of the distributor 22, wherein the micom 21 A channel tuning apparatus for television broadcasting signals, characterized in that AFT adjustment of the first channel selection section (23) is performed, and the second channel selection section (24) controls the channel selection with the tuning data of the first channel selection section (23). 2. The apparatus of claim 1, wherein the output signal of the first channel selection unit (23) is used as the main picture signal and the output signal of the second channel selection unit (24) is used as the sub picture signal. 2. The apparatus of claim 1, wherein the output signal of the first channel selection section (23) is used as a sub picture signal and the output signal of the second channel selection section (24) is used as a main screen signal.