KR950010316B1 - Complementary method for automatic tuning in broadcasting signal receiver - Google Patents

Abstract

the 1st step which decide whether user-desired broadcast signal is preset mode or not simultaneously with tuning operation by the received channel ;the 2nd step which memorizes 1st tuning data from the turning data of complete tuning if decided as presetmode ;the 3rd step which memorizes 2nd tuning data from the tuning data of the channel under receiving after the determined time ;the 4th step which compensates deviated freguency if the difference deviates the criterion range(α) after calculating the difference between the 1st and the 2nd tuning data.

Description

Automatic Tuning Compensation Method of Broadcast Signal Receiver

1 is a diagram illustrating frequency characteristics of a conventional TV or VCR.

2 is a block diagram of a receiver of a conventional TV or VCR.

3 and 4 are waveform diagrams according to one embodiment of FIG.

5 is a block diagram of a receiver of a TV or VCR according to the present invention.

6 is a flowchart illustrating an operation according to an embodiment of FIG. 5.

7 is a waveform diagram according to an embodiment of FIG.

* Explanation of symbols for main parts of the drawings

1: Key Matrix 2: Control Unit

3: pulse modulator 4: tuning controller

5: power supply unit 6: tuner unit

7: IF amplifier 8: Automatic frequency control

9: A / D converter

The present invention relates to a tuning compensation method of a receiver of a TV or VCR, and more particularly, to automatically compensating a tuning signal.

On the receiving side of a conventional TV or VCR, a tuner section for tuning a broadcast video signal coming from an antenna by a user and an image signal of the tuned tuner section are frequency-converted to obtain an IF (Intermediate Frequency) signal and then amplify the signal. It is divided into IF amplifier section, and tuner section includes RF amplifier, mixer and local oscillator.

The frequency band of the video signal through the tuner can be divided into the image IF (PIE), the voice IF (SIF) and the color carrier (CSCW) as shown in FIG. 1, and only when they are amplified to the indicated level, Color) is obtained. As shown in Figure 1, the level of image IF is at -6dB and the audio IF has a 920Hz beat between voice IF and color carrier, which affects the screen. Attenuate below 50dB.

However, if the local oscillation frequency provided by the local oscillator is changed, these relative relations are broken down, resulting in poor image quality.

That is, when the oscillation frequency is lowered, the positions of the respective carriers are shifted so that the luminance signal is emphasized in the low range, so that the resolution is lowered, and the color signal is reduced in level, so that the color does not become thin or come out. If the oscillation frequency is increased, the saturation of the color rises and the high frequency is emphasized.

This phenomenon requires more stability because color TV is more sensitive than black and white TV, and thus the need for a more stable tuning compensation circuit is increasing.

2 is a block diagram of a conventional TV or VCR receiving unit. A key matrix unit 1 for outputting a key signal selected by a user and an output signal of the key matrix 1 for outputting a pulse signal are shown. A control unit 2, a pulse width modulator 3 for outputting a pulse width modulated signal having a predetermined level value by the output signal of the control unit 2, an amplifier 4a and an integrator 4b; A tuning adjustment unit 4 for inverting and amplifying the output signal of the pulse width modulation unit 3, integrating a predetermined number of times, and outputting the power supply circuit 5a and regulator 5b; A power supply unit 5 for applying a constant voltage signal having a predetermined size to the unit 4 and a broadcast video signal input through the antenna ANT are used to output a broadcast channel desired by a user through the output signal of the tuning controller 4. A tuner section 6 for tuning and outputting, an amplifier 7a detector 7b, An IF amplification unit 7 having an intermediate frequency detection IC 7c and an LC resonator 7d, for detecting and amplifying and outputting only an image signal among the output signals of the tuner unit 6, the control unit 2, and The tuner unit 6 and the frequency control unit 8 output a frequency signal having a predetermined level value preset by the output signal of the IF amplifier unit 7 to the control unit 2.

A description of the operation of the prior art having the above-described configuration will be made as follows with reference to FIGS. 2 to 4.

While the broadcast video signal through the antenna ANT is being input to the tuner unit 6, the power signal provided from the power supply circuit 5a of the power supply unit 5 passes through the regulator 5b and is connected to the third (a). A constant voltage signal of 33 V, such as), is input to the amplifier 4a of the tuning controller 4. At this time, the tuning selection signal by the user inputs a waveform such as the third (b) diagram from the control unit 92 through the key matrix unit 1 to the pulse width modulator 3, and the pulse width modulator 3 The pulse signal modulated as shown in the third (c) diagram is input to the amplifier 4a of the tuning controller 4.

The modulated pulse signal applied to the amplifier 4a becomes an amplified pulse inverted in phase as shown in the third (d) diagram as the width thereof changes, and then has a variation range of 0V to 33V while passing through the integrator 4b. The smoothed voltage without the ripple component is applied to the tuner section 6. FIG. 3 (d) shows a state in which the integrator 4b is integrated in one stage and FIG. 3 (e) shows a state in which two stages are integrated.

In addition, the intermediate frequency detection IC 7c of the IF amplifier 7 detects only a video signal tuned by the tuner 6, and when the high level registered signal SYNC is detected, the automatic frequency controller 8 is detected. Inform the controller 2 of this. The controller 2 waits for the frequency control signal AFC ± by reducing the change in the modulated pulse width. That is, when the intermediate frequency signal detected by the IF amplifier 7 enters through the frequency control terminal FC of the control unit 2 through the frequency control unit 8, the output signal of the pulse output terminal PWM is controlled and pulsed. The change of the width modulation is stopped, and the TV receives a video signal of a desired frequency band, such as the fourth (c) degree.

Here, the point P of FIG. 4 (b) is a tuning point, and in order for the tuner 6 to perform the tuning operation correctly, the frequency band is switched and searched in the preset mode. In the normal mode, after tuning, the automatic frequency control signal (AFT ±) is operated to detect the phase difference of the image IF caused by the change of the local oscillator provided in the tuner unit 6 to detect the phase of the DC voltage to generate the local oscillation frequency. Keep it constant at all times.

In addition, in the intermediate frequency detection IC 7c, the LC resonance is performed through the LC resonator 7d in order to match the frequency of the local oscillator provided in the tuner unit 6 and the fourth (c) through the frequency control unit 8. The automatic frequency control signal such as) is applied to the control unit 2 and the tuner unit 6.

Therefore, the user notifies the control unit 2 of the signal indicating the normal mode through the key matrix unit 1 and transmits the frequency control signal set by the frequency control unit 8 to the tuner unit by the frequency control signal of the control unit 2. In this case, the broadcast signal of the desired channel is tuned and output.

However, the frequency of the local oscillator provided in the tuner portion of the conventional circuit is always changed according to temperature or environment, and only a constant voltage of a preset range is applied to the frequency control signal input terminal of the tuner portion, so that the tuning signal is released. There was a problem that could not be complemented.

In addition, when the high temperature aging or neglect tuning, the screen becomes messy, and in the case where a lot of tuning is involved, the compensation limit of the automatic frequency control signal is exceeded even if the user switches to the normal mode in which a predetermined channel is manually tuned. It had a disadvantage that could not be tuned.

In order to solve the disadvantage, the present invention detects a tuning control signal output from the tuning control unit to the tuner unit, converts the digital signal through the A / D converter, writes it in the control unit, and compares and modulates the pulse width after a predetermined time. Adjust the voltage to automatically compensate the applied voltage and output the compensated frequency signal.

Hereinafter, the configuration and one embodiment of the present invention will be described.

5 is a block diagram of a receiver of a TV or VCR according to the present invention, wherein a key matrix unit 1 for outputting a key signal selected by a user and an entire circuit by the output signal of the key matrix unit 1 are shown. And a pulse width modulator (3) for generating and outputting a predetermined control signal required for outputting the pulse signal, and for outputting the output signal of the controller 2 as a modulated pulse signal having a predetermined level value. ), An amplifier 4a and an integrator 4b, a tuning control unit 4 for phase inverting, amplifying, integrating and outputting the output signal of the pulse width modulating unit 3, and a power supply circuit ( 5a) and a regulator 5b, and a power supply unit 5 for applying a constant voltage signal having a predetermined level value to the tuning controller 4, and a tuning controller for broadcasting video signals input through an antenna ANT. By using the output signal of (4), user can select the desired broadcasting channel. A tuner section 6 for tuning and outputting an amplifier, an amplifier 7a, a detector 7b, an intermediate frequency detection IC 7c, and an LC resonator 7d; and a predetermined output signal of the tuner section 6 The tuner unit 6 and the control unit 6 transmit a frequency compensation signal having a predetermined level value by the IF amplification unit 7 for outputting the detected and amplified in the frequency band by the output signals of the control unit 2 and the IF amplification unit 7. 2 and an A / D converter 9 for digitally converting the output signal of the tuning controller 4 and outputting it to the controller 2. Operation of the present invention configured as described above will be described as follows with reference to FIGS. 5 to 7.

This proposal is a structure in which the A / D converter 9 is added to a conventional circuit, and since the basic operation is the same as that of the prior art, the description of the operation will be omitted, and the newly added A / D converter 9 is automatically centered. The focus of the operation description will be on the compensation of the tuning signal.

In the tuner unit 6, the A / D converter 9 is tuned in a state in which the desired channel frequency is tuned by the output signals of the tuning controller 4 and the frequency controller 8 and is not switched to the normal mode. The output voltage of (4) is converted into a digital signal, and the control unit 2 stores the tuning voltage and the modulated pulse signal corresponding to each channel.

After that, a predetermined channel is tuned by the user's key signal, and after a predetermined time T has elapsed, a difference in accuracy is compensated for compared to the first stored tuning data.

If the degree of the distorted distance is + X, the controller 2 compensates by + X in the same manner through the frequency controller 8.

7 shows the waveform of the modulated pulse signal according to this compensation. If there is no difference in comparison with the first tuning data recorded in the controller 2 here, the comparison operation is repeated after the predetermined cycle time T. If the user changes the channel before the predetermined cycle time T and starts tuning another broadcast frequency, the first memorized tuning data stored in the control unit 2 is reset and the new tuning data is stored.

Hereinafter, an embodiment of the present invention will be described in more detail with reference to FIG. 6. First, when tuning of the frequency signal desired by the user is completed in the tuner unit 6 shown in the block diagram of FIG. 5, the controller 2 checks whether or not the preset mode, and terminates the routine if it is not the preset mode. 2) digitally processes and tunes the tuning data TD corresponding to each channel, counts a predetermined predetermined cycle time, and when the preset cycle time TD _n reaches a preset cycle time TD _n , tuning data of each cycle time T _n . (TD _n ) is stored in the control unit 2.

Next, the difference between the tuning data TD ₁ memorized in the control unit 2 and the tuning data TD ₂ memorized later in the control unit 2 is compared with the reference value α of the tuning misalignment known from the control unit 2. If the reference value α is large, the memory data _first resets the stored tuning data TD ₁ , the _second memory only stores the tuning data TD ₂ , increases the period, and then compares the data after the period T ₃ .

If the reference value α is greater than the absolute value (│TD ₁ to TD _n │) of the difference between the two tuning data, and the difference value (TD ₁ to TD _n ) of the two tuning data is smaller than the negative reference value (-α) The frequency control unit 8 changes the automatic frequency control signal by + X, and if the difference between two tuning data (TD ₁ ~ TD _n ) is greater than the positive reference value (+ α), the automatic frequency control signal is changed by -X. Return to the routine for comparing the reference value α and the absolute value of the difference between the two tuning data.

As described above, the present invention is provided with a TV or a VCR that always has a clean and stable screen because it automatically compensates by detecting that the tuning is changed in the preset mode.

Claims (2)

A first step of determining whether the user is in a preset mode while performing a tuning operation on a channel receiving a desired broadcast signal, and a second step of storing tuning data of the tuned channel as a first tuning data value in the preset mode; After a predetermined time, the third step of storing the tuning data of the channel currently being received as a second tuning data value, the difference between the first and second tuning data is calculated and the difference is outside the tuning misalignment reference range (α) Comprising a fourth step for compensating for the deviation frequency size automatic tuning method of the receiver. The method of claim 1, wherein the fourth step comprises sequentially storing the second tuning data value as the first data value after the difference between the first and second tuning data values falls within a Neutralization reference range. Autotuning compensation method for a broadcast signal receiver characterized in that it further comprises repeating.