KR0158963B1 - Circuit and method for automatic fine tuning - Google Patents

Abstract

The present invention provides a base station data memory 34 for storing forward tuning data on a broadcast standard, a correction tuning data obtained by automatic fine adjustment in the manufacturing process of a broadcast receiver, and a stationary data stored in the base station data memory 34. A correction data memory 36 for storing correction data corresponding to a difference value from the tuning data, and an AFT voltage which is proportional to a change in the intermediate frequency from the automatic fine adjustment voltage detector 20 when the broadcast receiver is used, and receives a reference voltage. And a data processing unit 38 which obtains the correction tuning data and compares the correction tuning data with the correction data stored in the correction data memory, and outputs the correction tuning data to the tuner 10. The present invention relates to an automatic fine tuning circuit and a method thereof, by automatically correcting a circuit error occurring during a manufacturing process of a broadcast receiver. Correct enable the automatic fine tuning.

Description

Automatic fine tuning circuit and its method

1 is a schematic block diagram of a television comprising an automatic fine tuning circuit according to the prior art.

(A) of FIG. 2 is a graph showing the state of the intermediate frequency and the reference voltage when there is no circuit error in the automatic fine tuning circuit.

(B) of FIG. 2 is a graph showing the state of the intermediate frequency and the reference voltage when there is a circuit error in the automatic fine tuning circuit.

3 is a schematic block diagram of a television including an automatic fine tuning circuit according to an embodiment of the present invention.

4 is a flowchart illustrating a process of obtaining correction data according to the present invention.

5 is a flowchart illustrating a process of performing automatic fine adjustment according to the present invention.

* Explanation of symbols for main parts of the drawings

10 tuner 12 high frequency amplifier

14 Local Oscillator 15 Variable Capacitance Diode

16: Mixer 18: Image Intermediate Frequency Amplifier

20: automatic fine adjustment voltage detector 22; Image detector

24: image carrier amplifier 26: amplitude limiter

28: frequency discriminator 30: DC amplifier

32: microcomputer 34: reference station data memory

36: correction data memory 38: data processing unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic fine tuning (AFT) circuit and a method thereof, and in particular, an automatic fine tuning circuit which automatically corrects a circuit error occurring during a manufacturing process of a broadcast receiver to enable more accurate automatic fine tuning. And to a method thereof.

In general, the automatic fine tuning circuit selects a specific channel according to the tuning signal of the microcomputer in the broadcast receiver and finely adjusts the local oscillation frequency so that an accurate intermediate frequency can be obtained.

1 is a schematic block diagram of a television including a conventional automatic fine tuning circuit, wherein the television outputs an image intermediate frequency signal by mixing a high frequency signal received through an antenna with a local oscillation signal oscillated according to a tuning signal. An image intermediate frequency amplifier 18 for amplifying the image intermediate frequency signal outputted from the tuner 10, increasing sensitivity, increasing selectivity and increasing image output, and the tuner 10; Automatically fine-tunes the local oscillation frequency generated by the autonomous voltage detection unit 20 to obtain an accurate image intermediate frequency, and the image intermediate frequency signal amplified by the image intermediate frequency amplifier 18 detects and outputs an image signal. The image detector 22 and the automatic fine-tuned voltage detector 20 receive an AFT voltage proportional to the variation in the image intermediate frequency, and transmit the tuning control signal to the tuner 10. To include a microcomputer 32 for outputting.

The tuner 10 includes a high frequency amplifier 12 for amplifying a weak high frequency signal received through an antenna to increase sensitivity and improving a signal-to-noise ratio, and a local oscillator 14 for generating a high frequency signal required for frequency conversion. And a variable capacitance diode 15 for fine-tuning the local oscillation frequency of the local oscillator 14 according to the tuning control signal output from the microcomputer 32, and a high frequency signal output from the high frequency amplifier 12. And a mixer 16 for mixing the high frequency signals generated by the local oscillator 14 and outputting an image intermediate frequency signal.

The automatic fine-tuned voltage detector 20 extracts and amplifies an image carrier of 45.75 MHz among the image intermediate frequency signals output from the image intermediate frequency amplifier 18, and the image carrier amplifier 24. An amplitude limiter 26 which makes the amplitude of the amplified video carrier constant, a frequency discriminator 28 for outputting a DC voltage proportional to the variation in the image intermediate frequency of the image intermediate frequency signal, and the frequency discriminator 28 It consists of a DC amplifier 30 for amplifying the DC output voltage output from.

The operation of the conventional automatic fine adjustment circuit configured as described above is as follows.

First, when the mixer 16 mixes a high frequency signal output from the high frequency amplifier 12 and a high frequency signal generated by the local oscillator 14 and outputs an image intermediate frequency signal, the image intermediate frequency amplifier 18 is a mixer 16. It receives the image intermediate frequency signal from the amplifier and amplifies it to increase sensitivity, increase selectivity, and increase image output.

The image carrier amplifier 24 of the automatic fine-tuned voltage detector 20 extracts and amplifies 45.75 MHz of the image intermediate frequency signal output from the image intermediate frequency amplifier 18, and the amplitude limiter 26 the image carrier amplifier. The amplitude of the image carrier amplified by (24) is made constant and then output to the frequency discriminator 28 whose center frequency is adjusted to 45.75 MHz, after which the frequency discriminator 28 and the DC amplifier 30 output the image. Outputs FM detection voltage proportional to the variation of intermediate frequency.

Subsequently, the microcomputer 32 converts the DC FM detected voltage input from the DC amplifier 30 to the A / D converter terminal into a digital signal and performs automatic fine adjustment to perform a variable capacitance diode connected to the local oscillator 14 ( Apply tuning control data to 15). The variable capacitance diode 15 decreases capacitance when the reverse bias voltage increases, and increases capacitance when the reverse bias voltage decreases.

At this time, the frequency discriminator 28 is proportional to the fluctuation of the image intermediate frequency and is amplified by the DC amplifier 30 and the DC voltage input to the A / D converter terminal of the microcomputer 32 becomes an automatic fine adjustment voltage.

If the local oscillation frequency oscillated by the local oscillator 14 is lowered due to voltage fluctuations or temperature changes, the intermediate frequency of the image intermediate frequency signal output from the mixer 16 is lowered. Tuning control data is applied to the variable capacitance diode 15 to increase the reverse bias voltage to decrease the capacitance to adjust the local oscillation frequency.

On the contrary, if the local oscillation frequency is increased and the intermediate frequency is increased, the microcomputer 32 applies the reduced tuning control data to the variable capacitance diode 15 to reduce the reverse bias voltage and increase the capacitance to adjust the local oscillation frequency to be lowered. do.

On the other hand, due to a circuit error occurring during the manufacturing process of the broadcast receiver, when the broadcast receiver is used, the AFT voltage is stored in the microcomputer even when the constant frequency and the tuning data (correct tuning voltage) according to the broadcast specifications are input to the variable capacitance diode. There was a case where it did not match the reference voltage.

(A) of FIG. 2 is a graph showing the state of the intermediate frequency and the reference voltage when there is no circuit error in the automatic fine tuning circuit. When the positive tuning data (positive tuning voltage) is input, the AFT voltage at ⓐ is the reference voltage. And the intermediate frequency also matches.

However, when there is a circuit error in the automatic fine tuning circuit, as shown in (b) of FIG. 2, when the frequency shifts from ⓐ to the left, the intermediate frequency decreases by Δf, and the AFT voltage in ⓒ Decreases by ΔV over the voltage. On the contrary, when the frequency shifts from ⓐ to the right, the intermediate frequency is increased by Δf at ⓓ and the AFT voltage is increased by ΔV from the reference voltage at ⓔ.

The reference voltage refers to the AFT voltage output from the automatic fine-tuned voltage detector 20 when the microcomputer 32 obtains the correct intermediate frequency by inputting the constant frequency and the constant tuning data specified in the broadcast standard to the variable capacitance diode 15. The microcomputer 32 converts and stores the data of the reference voltage.

Conventionally, in order to correct the deviation of the AFT voltage due to the circuit error of the broadcasting receiver as described above, that is, to adjust the AFT voltage to the reference voltage, the AFT coil value of the frequency discriminator provided in the automatic fine-tuned voltage detector was adjusted. The work is a very cumbersome and accurate adjustment because the worker manually adjusts the AFT coil value manually and checks the adjustment result with an oscilloscope.

The present invention has been made to solve the above problems, and provides an automatic fine tuning circuit and a method for automatically and automatically fine-tuning by automatically correcting the circuit error generated in the manufacturing process of the broadcast receiver. Its purpose is to.

In order to achieve the above object, the automatic fine adjustment circuit according to the present invention includes a tuner, an automatic fine adjustment voltage detection unit, and a microcomputer that receives an AFT voltage from the automatic fine adjustment voltage detection unit and outputs tuning control data to the tuner. In the broadcast receiver, the microcomputer stores the reference tuning data memory for storing the tuning data according to the broadcast standard, the correction tuning data obtained by the automatic fine tuning in the manufacturing process of the broadcasting receiver, and the tuning information stored in the reference tuning data memory. Compensation data memory for storing correction data corresponding to a difference value from the tuning data, and AFT voltage which is proportional to the variation of the intermediate frequency from the automatic unadjusted voltage detector when the broadcast receiver is used, and compared with the reference voltage to adjust the tuning data. After obtaining the data stored in the correction data memory And a data processor for outputting correction tuning data corresponding to a value obtained by adding the correction data to the tuner.

The reference voltage is the AFT voltage output from the automatic fine-tuned voltage detector when the constant frequency and the right tuning data specified in the broadcast standard are input to the tuner by the microcomputer to obtain an accurate intermediate frequency.

In addition, the automatic fine tuning method according to the present invention includes a first step of tuning the fine tuning data set as initial tuning data in an automatic fine tuning method of a broadcast receiver; A second step of converting the AFT voltage output by the tuning of the first step into a digital signal; A third step of determining whether an AFT voltage converted into a digital signal in the second step is equal to a reference voltage; A fourth step of correcting the tuning data to obtain corrected tuning data when it is determined that the AFT voltage is different from the reference voltage in the third step; If it is determined in the third step that the AFT voltage is equal to the reference voltage, the fifth step of tuning to the correction tuning data obtained by adding the correction data obtained in the manufacturing process of the broadcast receiver to the correction tuning data obtained in the fourth step It features.

In the correction data, the first step of inputting a constant frequency according to a broadcast standard in the manufacturing process of the broadcast receiver and tuning to the constant tuning data which is initial tuning data; A second step of converting the AFT voltage output by the tuning of the first step into a digital signal; A third step of determining whether an AFT voltage converted into a digital signal in the second step is equal to a reference voltage; A fourth step of correcting the tuning data to obtain the corrected tuning data when the AFT voltage is determined to be different from the reference voltage in the third step; When the AFT voltage is determined to be equal to the reference voltage in the third step, it is preferable to obtain the fifth step of storing the difference between the corrected tuning data and the right tuning data obtained after performing the AFT in the fourth step.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

FIG. 3 is a schematic block diagram of a television including an automatic fine tuning circuit according to an embodiment of the present invention, wherein the television mixes a high frequency signal received through an antenna with a local oscillation signal oscillated according to a tuning signal. A tuner 10 for outputting a frequency signal, an image intermediate frequency amplifier 18 for amplifying an image intermediate frequency signal output from the tuner 10, increasing sensitivity, increasing selectivity, and increasing image output; Automatic fine-tuned voltage detector 20 for automatically fine-tuning the local oscillation frequency generated by the local oscillator of the tuner 10 to obtain an accurate image intermediate frequency, and the image intermediate frequency signal amplified by the image intermediate frequency amplifier 18. And a video detector 22 for outputting a video signal and a microcomputer 32 storing a reference voltage C as in the prior art.

The microcomputer 32 includes a reference tuning data memory 34 for storing the forward tuning data A in accordance with a broadcast standard, a correction tuning data obtained by automatic fine adjustment during the manufacturing process of the television, and the reference tuning data memory 34. AFT voltage proportional to the fluctuation of the intermediate frequency from the correction data memory 36 which stores the correction data E corresponding to the difference value from the right tuning data stored in the data, and the automatic fine adjustment voltage detection unit 20 when the television is used. The correction tuning data (G) is obtained by comparing with the reference voltage (C), and the correction tuning data (G) corresponds to the value obtained by adding the correction data (E) stored in the correction data memory (36). And a data processor 38 for outputting correction tuning data H to the tuner 10.

Referring to the operation and effects of the present invention configured as described above in detail.

First, the tuner 10 outputs an intermediate frequency signal by mixing a high frequency signal received through an antenna with a local oscillation signal oscillated according to a tuning signal, and the image intermediate frequency amplifier 18 is output from the tuner 10. It amplifies the middle frequency signal to increase the sensitivity, selectivity and the image output.

The automatic fine-tuned voltage detector 20 inputs an AFT voltage proportional to the variation of the image intermediate frequency of the image intermediate frequency signal output from the image intermediate frequency amplifier 18 to the A / D converter terminal of the microcomputer 32. The AFT voltage is converted into a digital signal by the A / D converter and input to the data processor 38. The data processor 38 receives the right tuning data A from the reference channel data memory 34 and corrects the difference between the corrected tuning data D and the right tuning data A obtained after performing the automatic fine adjustment. The data E is obtained and stored in the correction data memory 36. The correction data E is data for correcting an error of the AFT coil.

The corrected tuning data D obtained after the automatic fine tuning is tuned to the preset tuning data A according to the broadcast standard, but the AFT voltage B does not match the reference voltage C due to a circuit error. Since the positive tuning data A is larger or smaller than the reference voltage C so that the AFT voltage B is larger or smaller than the reference voltage C, the correct tuning data A is positive and negative. The correction data E corresponding to the difference from the tuning data A is a data value of + or-.

Therefore, in the future, when the user views the television, the data processing unit 38 of the microcomputer 32 reads the correction data E previously stored in the correction data memory 36 during the manufacturing process of the television, and performs the automatic fine adjustment. In addition to the correction tuning data G thus obtained, correction tuning data H corrected to a circuit error is obtained, and finally output to the tuner 10.

Therefore, even if the AFT coil value is not manually adjusted as in the prior art, the circuit error is automatically corrected, so that the automatic fine adjustment is more accurate than the prior art.

4 is a flowchart illustrating a process of obtaining correction data according to the present invention, and FIG. 5 is a flowchart illustrating a process of performing automatic fine adjustment according to the present invention. The process of doing this is explained in detail.

First, in the process of manufacturing a television, the data processing unit 38 of the microcomputer 32 inputs an accurate constant frequency of a specific channel that is already known to the tuner 10 (S101).

After the step S101, the data processing unit 38 sets the right tuning data A, which is reference tuning data according to the broadcast standard, as initial tuning data (S102).

After the step S102, the data processor 38 outputs the right tuning data A set as the initial tuning data to the tuner 10 so that tuning is performed (S103).

After the step S103, the A / D converter of the microcomputer 32 converts the AFT voltage B inputted from the automatic fine adjustment voltage detector 20 after tuning by the forward tuning data A into a digital signal, thereby converting the data processor 38 into a digital signal. Output to (S104).

After the step S104, the data processor 38 compares the input AFT voltage B with the reference voltage C previously stored in the microcomputer 32 to determine whether they match (S105).

If the AFT voltage (B) and the reference voltage (C) does not match as a result of the determination in step S105, the data processing unit 38 modifies the current tuning data to obtain the corrected tuning data (D) (S106) and then the corrected tuning data ( D) is output to the tuner 10 so that tuning is performed again. Steps S103 to S106 are repeatedly performed until the AFT voltage B and the reference voltage C are equal.

After repeating the steps S103 to S106, corrected tuning data D is obtained such that the AFT voltage B and the reference voltage C are the same, and as a result of the determination of step S105, the AFT voltage B and the reference voltage C are obtained. ), The data processor 38 reads the right tuning data A stored in the reference channel data memory 36, and then compares the difference with the corrected tuning data D obtained after repeating steps S103 to S106. It calculates and stores the calculation result value, ie, correction data E, in correction data memory 36 (S107).

After that, when a television having the correction data E stored in the correction data memory 36 is used, the data processing unit 3 of the microcomputer 32 is stored in the reference channel data memory 34. After the right tuning data A is set as initial tuning data (S201), it is output to the tuner 10 so that tuning is performed (S202).

After the step S202, the A / D converter of the microcomputer 32 converts the AFT voltage F input from the automatic fine adjustment voltage detector 20 into a digital signal and outputs the digital signal to the data processor 38 (S203).

After the step S203, the data processor 38 compares the AFT voltage F and the reference voltage C stored in the microcomputer 32 to determine whether they match (S204).

If the AFT voltage (F) and the reference voltage (C) does not match as a result of the determination in step S204, the data processing unit 38 modifies the current tuning data to obtain corrected tuning data (G) (S205). G) is output to the tuner 10 to be tuned again. Steps S202 to S205 are repeated until the AFT voltage F and the reference voltage C are equal.

If the corrected tuning data G is obtained such that the AFT voltage F and the reference voltage C are the same after repeating the steps S202 to S205, the determination result of the step S204 results in the AFT voltage F reference voltage C. The data processing unit 38 adds the correction data E read from the correction data memory 36 to the correction tuning data G obtained after repeating the steps S202 to S205. The correction tuning data H is output to the tuner 10 so that tuning is performed (S207). At this time, the corrected tuning data G obtained after repeating steps S202 to S205 is data for correcting various errors (different from circuit errors generated in the manufacturing process) generated when the TV is used.

That is, since the circuit error cannot be corrected only by the correction tuning data G obtained after repeating the steps S202 to S205, the tuning is performed by adding the correction data E to the correction tuning data G in step S206.

As described above, the present invention obtains and stores correction data for correcting a circuit error in a manufacturing process of a broadcast receiver, and corrects tuning data obtained by performing an automatic fine adjustment when using a broadcast receiver (for correcting various errors generated during use). Since the tuning is performed with the correction tuning data obtained by adding the correction data to the data, it is possible to obtain a more accurate intermediate frequency quickly and conveniently.

Claims (4)

A broadcast receiver having a tuner 10, an automatic fine adjustment voltage detection unit 20, and a microcomputer 32 for receiving AFT voltage from the automatic fine adjustment voltage detection unit 20 and outputting tuning control data to the tuner 10. In the above, the microcomputer 32 includes a reference station data memory 34 for storing the tuning data according to the broadcast standard, a correction tuning data obtained by automatic fine adjustment in the manufacturing process of the broadcast receiver, and the reference station data memory ( A correction data memory 36 for storing correction data corresponding to a difference value from the right tuning data stored in 34), and proportional to the fluctuation of the intermediate frequency from the automatic fine adjustment voltage detector 20 when the broadcast receiver is used. The correction tuning data is obtained by receiving the AFT voltage and comparing it with the reference voltage, and the correction tuning data is added to the correction data stored in the correction data memory. Data to output a corrected tuning data to the tuner 10 processing unit 38, automatic fine tuning circuit, characterized in that configured to include. According to claim 1, wherein the reference voltage is the automatic fine-tuning voltage detection unit 20 when inputting the constant frequency and the tuned data specified in the broadcast standard to the tuner 10 from the microcomputer 32 to obtain an accurate intermediate frequency Automatic fine adjustment circuit characterized in that the output AFT voltage. An automatic fine tuning method of a broadcast receiver, comprising: a first step of tuning to forward tuning data set as initial tuning data; A second step of converting the AFT voltage output by the tuning of the first step into a digital signal; A third step of determining whether an AFT voltage converted into a digital signal in the second step is equal to a reference voltage; A fourth step of correcting the tuning data to obtain corrected tuning data when it is determined that the AFT voltage is different from the reference voltage in the third step; If it is determined in the third step that the AFT voltage is equal to the reference voltage, the fifth step of tuning to the correction tuning data obtained by adding the correction data obtained in the manufacturing process of the broadcast receiver to the correction tuning data obtained in the fourth step Automatic fine adjustment method characterized by. 4. The method of claim 3, wherein the correction data comprises: a first step of inputting a constant frequency according to a broadcast standard in a manufacturing process of the broadcast receiver and tuning to constant tuning data which is initial tuning data; A second step of converting the AFT voltage output by the tuning of the first step into a digital signal; A third step of determining whether an AFT voltage converted into a digital signal in the second step is equal to a reference voltage; If it is determined in the third step that the AFT voltage is different from the reference voltage, modifying the tuning data to obtain the corrected tuning data and tuning; And if the AFT voltage is determined to be equal to the reference voltage in the third step, obtaining the fifth step of storing the difference between the corrected tuning data and the right tuning data obtained after performing the AFT in the fourth step.