JPH04196891A - Television set - Google Patents

Abstract

PURPOSE:To stabilize the adjustment point at the time of switching a channel and even if a multi-color television signal is received by providing one signal processing signal, and a means for supplying a reference signal generated by an oscillator to the signal processing circuit, and executing a signal processing or the control. CONSTITUTION:In a horizontal oscillating circuit 15, a VCO oscillated by a frequency of 32 folds a horizontal frequency is provided, and a PLL is formed with use of a horizontal synchronizing signal. In a burst gate pulse generating circuit 10, a pulse is generated, based on an output timing pulse of the horizontal oscillating circuit 15, and a burst gate pulse GP is formed by masking it by the horizontal synchronizing signal. The burst gate pulse GP is outputted to a color synchronizing/reproducing circuit 7 and a color signal demodulating circuit 6, and it is used as a timing signal for sampling a burst. As a result, a clock of an automatic adjusting circuit 5 is not influenced at all by color synchronization and horizontal oscillation. In such a way, a stable adjustment can be obtained without being influenced by the adjusting circuit at the time of switching a channel and even if a multi-color television signal is received.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a television receiver, and is directed to reducing the number of adjustment points and improving changes over time in signal processing characteristics.

(Prior art) Chroma signal processing block 1 of conventional television receiver
00 and a portion of the synchronization signal processing block 200 are shown in FIG.

The chroma signal of the composite video signal is separated from the composite video signal by a comb filter, etc., and when receiving the on-air signal input to terminal 1, a Nyquist filter is used in signal processing at the video intermediate frequency. Because it passes,
The sideband components of the chroma signal have unbalanced amplitudes between upper and lower sidebands. To correct this, T
A flat band is obtained when the amplitudes of the upper and lower sidebands are demodulated through a filter called an OF (tick-off filter) 3. Unlike this, VTR
When a video signal is line-input from a signal source such as a video disc or a video disc, the sideband components of the chroma signal are input as flat because they do not pass through the intermediate frequency stage. For this reason, a BPF (band pass filter) 4 is provided to extract the chroma signal flatly, so that amplitude manipulation is not performed in the case of a line input signal. Which filter to use is determined by controlling the switch SW from the outside using a mode control controller such as a microcomputer, thereby switching the signal path and attaching/attaching the filter.

The eight switches SW are input to the color signal demodulation circuit 6, demodulated into color difference signals, and outputted from the terminal 12 to the outside. A continuous wave signal CW necessary for demodulation is output from the color synchronization reproducing circuit 7. The color synchronization reproducing circuit 7 inputs the burst signal B component of the input chroma signal from the color signal demodulation circuit 6 and outputs the burst signal B component of the input chroma signal to the crystal 8.
A continuous wave CW is obtained by locking the frequency of the oscillation circuit using the PLL to the burst signal B using a PLL. The color synchronization reproducing circuit 7 outputs this continuous color subcarrier signal fsc from the terminal 13 as a clock for the comb filter.

The color subcarrier is also output to an automatic adjustment circuit 5 that automatically adjusts the filters of the TOF 3 and BPF 4. Automatic adjustment circuit 5
Since the frequency of the input fsc is accurate, it is used as a time reference signal, and a feedback loop is used to adjust the time constants of the capacitor C and resistor R built into the IC to a certain set value. Since the center frequency of a filter built in an IC can be controlled by changing the bias current of the amplifier, the automatic adjustment circuit 5 determines the bias current of the amplifier.

In the synchronization signal processing block 200, the horizontal synchronization signal separated by the synchronization separation circuit 9 from the terminal 2 into which the composite signal is input is outputted to the horizontal oscillation circuit 15 and the -st gate generation circuit 10. The horizontal oscillation circuit 15 has a horizontal frequency fH
It has a vCO that oscillates at a frequency 32 times higher than that of the previous one, and is combined with a horizontal synchronization signal and PLL. The burst gate pulse generation circuit 10 generates a pulse based on the output timing pulse of the horizontal oscillation circuit 15, and masks it with a horizontal periodic signal to form a burst gate pulse GP.

By incorporating a chroma signal input filter into the IC and automatically adjusting it, peripheral components can be incorporated without increasing the number of adjustment points.

Fundamentally, in the circuit with the above configuration, TOF or BPF4
The drawback is that the automatic adjustment of the timing is slow. When a video signal arrives from a no-signal period due to channel switching or the like, the horizontal oscillation circuit 15 first locks to the horizontal synchronizing signal. After locking, the burst gate pulse generation circuit 10 generates a burst gate pulse GP at a regular position, and the color synchronization circuit 7 pulls it into the burst frequency.

When the pull-in is completed, the phase of the continuous wave CW for demodulation becomes the phase to be demodulated, and the correct hue is displayed on the screen. The timing at which this color synchronization circuit 7 draws the frequency into the burst signal B is after the horizontal oscillation PLL is locked, and the automatic adjustment circuit 5 inputs a reference time signal from this fsc and stably outputs the adjustment current. Until then,
It will take some more time. Therefore, since the center frequency of the chroma filter is adjusted after the color signal is output to the screen, the saturation level and hue of the color appear to fluctuate momentarily, impairing the image quality.

Furthermore, PAL-S ECA, which is currently being broadcast around the world,
Of the M-NTSC systems, a multicolor television receiver that receives PAL and NTSC has 3.58M) Iz and 4.43M) Iz in the color synchronization reproduction circuit 7.
It has two types of crystals, and the crystal to be used is switched depending on the judgment result of the reception method discrimination circuit. Since the automatic adjustment circuit 5 takes the reference signal to be adjusted from the fsc signal period, there is a problem in that when the color synchronization frequency changes, the reference signal period changes and the adjustment point also changes.

(Problems to be Solved by the Invention) With the above-mentioned conventional method, it takes time to automatically adjust the TOF and BPF filters, and the saturation and hue of colors appear to fluctuate momentarily, resulting in a loss of image quality. In the circuit that automatically adjusts the filter, the reference signal is obtained from the fsc signal synchronization, so if the color synchronization frequency changes, the reference signal period changes and the adjustment point also changes.

The present invention provides a television receiver in which deterioration in image quality is suppressed by speeding up the automatic adjustment time of a filter, and in which the adjustment point is stable even when changing channels or receiving a multicolor television signal.

[Structure of the Invention] - (Means for Solving the Problem) The television receiver of the present invention processes at least one video signal, chroma signal, and deflection signal of a composite video signal.
and an oscillator for generating a reference signal, which is different from that for reproducing color subcarriers and horizontal frequencies, and supplies the reference signal generated by the oscillator to the signal processing circuit for signal processing or and control means.

(Function) In this invention, a crystal oscillation circuit is built in separately from the color subcarrier regeneration oscillator of the color synchronization circuit, and this oscillation signal is used to supply clocks to various adjustment circuits. The adjustment circuit is not affected by the input signal even if the input signal is received, and the adjustment point can be made stable.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The same reference numerals as in FIG. 3 are used for synchronization. 1st
In the figure, terminal 1 of the chroma signal processing block 100'
Input the chroma signal to.

The signals passed through TOF3 and BPF4 are switched by switch SW. The switch S field output is input to the color signal demodulation circuit 6, and the demodulated color difference signal is outputted from the terminal 12. The color synchronization reproducing circuit 7 uses the burst signal B input from the color signal demodulation circuit 6 and a VC using a 3.58 MHz crystal.
The oscillation signal of the XO circuit is locked by PLL. The oscillating continuous wave CW is input to the color signal demodulation circuit 6 as a demodulation signal. This color subcarrier fsc oscillation signal is outputted to the outside from a terminal 13 as a clock for a comb filter or the like. In addition to this oscillation circuit, an oscillation circuit 1 using a crystal 18
6 is prepared, and this oscillation signal fadj is output to an automatic adjustment circuit 5 that automatically adjusts the filter.

The automatic adjustment circuit 5 uses the period of this reference signal as a time reference, and adjusts the center frequencies of the TOF 3 and BPF 4 by adjusting the time constant of CR.

The synchronization signal processing block 200 outputs a horizontal synchronization signal separated by the synchronization separation circuit 9 from the composite synchronization signal supplied to the terminal 2 to the horizontal oscillation circuit 15 and the burst gate generation circuit 10. The horizontal oscillation circuit 15 has a vCO that oscillates at a frequency 32 times the horizontal frequency, and is combined with a horizontal synchronization signal and a PLL. The burst gate pulse generation circuit IO generates a pulse based on the output timing pulse of the horizontal oscillation circuit 15, and masks it with a horizontal synchronization signal to form a burst gate pulse GP. The burst gate pulse CP is output to the color synchronization reproduction circuit 7 and the color signal demodulation circuit 6, and is used as a timing signal for burst extraction.

In this way, the clock of the automatic adjustment circuit 5 is completely unaffected by color synchronization and horizontal oscillation, so that the adjustment point of the filter becomes completely independent of the operating states of vcxo and vco, and is stable.

In addition, in the case of a ROMA signal processing circuit capable of multi-color reception, even if the oscillation frequency of the oscillation circuit for color subcarrier reproduction is switched, the signal from the oscillator 16 is input to the filter automatic adjustment circuit, so the frequency will not change. Therefore, the operating point of the filter adjustment circuit 5 is stable.

Therefore, the color saturation and hue of the screen do not fluctuate when switching channels, and even when a multicolor television signal is received, good filter adjustment is possible and stable screen images can be obtained.

The f adj signal is very useful not only in chroma signal processing 100' but also in video and synchronization blocks.

This point will be explained. First of all, in modern video units, it has become popular to use a built-in delay line as an image quality correction circuit that sharpens or softens the edges of the video signal. is used. When automatically adjusting the frequency or group delay characteristics of this filter, if this reference signal is available, the operating point of the adjustment circuit will be stable for the reasons mentioned above, and the image quality will not be blurred (very suitable. Synchronization signal In the processing section, variation in the time constant becomes a problem.In the vertical synchronization signal separation circuit that integrates the vertical synchronization signal, creates a trapezoidal wave, and then slices it to separate the vertical synchronization signal, variation in the time constant causes a problem in the integration sensitivity. This appears as variations in the slope of the trapezoidal wave.In this case, the delay from the input of the separated vertical synchronization signal will vary, and the screen position will vary depending on the circuit.Also, the field even/odd determination will be different. There is a possibility that the required system will not be able to do this.f
If there is a signal like adj, TOF 3, BPF 4
The time constant can be adjusted in the same manner as the above adjustment, and a vertical synchronization separation circuit having a constant and consistent time constant can be provided.

FIG. 2 is a block diagram of a television receiver for explaining the ripple effect of using this invention. The channel signal selected by the tuner 20 is input to the video and audio intermediate frequency signal detection circuit 21, and the detected baseband composite video signal is output to the Y/C separation circuit 22. Input the baseband audio signal to the audio multiplex decoder 23,
The audio signal subjected to audio multiplexing and decoding is output to a surround processor 24, and after special effects are applied, it is reproduced from a speaker 3. The output of the Y/C separation circuit 22 is V/C/D2
5 video signal processing section 26. The signal is supplied to the chroma signal processing section 27 and the deflection signal processing section 28, respectively, and S E CA
If the system also supports the M system, the chroma signal is also input to the S E CA M system chroma signal processing circuit 30 . S
The output of the ECAM type chroma signal processing circuit is V/C/D2
5, and outputs the color difference signal and video signal subjected to madrisk processing by the /C/D 25 to the AKB 29. AKB
At step 29, the white balance is adjusted and output as a video signal for the CRT 32. The retrace position of the screen is determined by the output signal of the deflection signal processing circuit 28 and scanned.

Furthermore, the above-mentioned f adj signal is supplied to each circuit which can be constructed from an IC as shown in FIG.

In this way, the V/C/D25 supplies a reference signal that cannot normally be provided by each IC alone due to increased cost, so by simply providing an input pin on each IC, external components can be obtained without increasing the number of components. I can do it. Furthermore, since it is not affected by the presence or absence of input or the signal system, it is extremely stable, and the adjustment circuit of each IC operates stably after power is turned on.

Furthermore, even if the signal processing of some of the peripheral ICs is completely digitalized, this fadj signal can be applied as a clocked signal, which improves the usability of the peripheral ICs and improves the flexibility for upgrading.

Basically, the frequency of the FADJ signal may be any frequency. For boat fishing, it seems easy to use a positive multiple of the horizontal frequency. and (if used in the PAL system, 4 M
Hz (256fH) 0') positive multiple, especially 8 MHz is the most promising.

[Effects of the Invention] As explained above, according to the television receiver of the present invention, a stable adjustment point is obtained without being affected by the adjustment circuit even when changing channels or receiving a multicolor television signal. be able to.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing chroma signal processing and deflection signal processing blocks of a television receiver according to an embodiment of the present invention, and FIG. 2 is a system diagram in which the embodiment of the present invention is applied to multicolor vision signals. FIG. 3 is a conventional system diagram. 3...TOF 4...BPF 5...Automatic adjustment circuit 6...Color difference signal demodulation circuit 7...・・・・・・
・・Color synchronization reproduction circuit 8.18・Crystal 16・・・・・Oscillation circuit

Claims (2)

[Claims] (1) At least one signal processing circuit out of the circuits that process the video signal, chroma signal, and deflection signal of the composite video signal, and an oscillator for generating a reference signal different from that for reproducing the color subcarrier and horizontal frequency. A television receiver comprising: means for supplying a reference signal generated by the oscillator to the signal processing circuit for signal processing or control. (2) The television receiver according to claim 1, wherein the oscillation frequency of the oscillator for generating the reference signal is set to a frequency that is a positive multiple of the horizontal frequency.