KR910005538Y1 - B/w signal definition compensation circuit of color tv - Google Patents

Abstract

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Description

Black and white signal resolution correction circuit for color broadcasting

1 is a circuit diagram of the present invention.

FIG. 2A is a diagram of each waveform when the input signal has a chroma component, and b is a diagram of each waveform when the input signal has no chroma component.

* Explanation of symbols for main parts of the drawings

1: peak detection circuit. 2: comparator

3: 3.58 MHz trap 4: chroma signal processor

IC ₁ : Monostable Multivibrator IC ₂ , IC ₃ : CMOS Switch

OP ₁ , OP ₂ : Op amp AN: Endgate

I ₁ : Inverter

The present invention relates to a black and white signal resolution correction circuit for color broadcasting to correct the resolution of black and white signals in color TVs and monitors that reproduce color signals.

Conventionally, mono broadcasting is reproduced by outputting a color killer pulse in a mono signal by judging whether a mono signal and a color signal are present as a burst signal as a technique related to chroma signal processing.

That is, since the color signal and the mono signal are conventionally discriminated only by the presence or absence of a burst, the signal with the burst is determined as a color signal even if the signal is composed of only white or black, and the chroma processing unit RY (B-Y) is sent out.

At this time, in case of the bursted signal consisting of only white or black signal, when the color component is taken from the luminance / color separation filter, a signal near 3.58 MHz included in the burst and luminance components is output. This signal is applied to the chroma processing unit. Unnecessary noise waveforms appear on the output side of the color difference signal RY (B-Y).

The color-difference signal R-Y (B-Y) output including such a noise waveform is applied to the matrix circuit at the rear end to slightly deform the original black or vaccine code, thereby reducing the resolution.

The 3.58 MHz trap also attenuates the luminance signal around 3.58 MHz, which is another cause of lowering the resolution.

In view of the above, the present invention considers the color signal and the mono signal as the chroma signal instead of the burst signal, and in the case of a signal having a burst composed of a white or black signal, the signal is judged as a mono signal instead of a color signal. In order to prevent degradation, black and white signals without chroma components, even with burst signals, detect chroma signals, shorten the chroma signal input of the chroma processing unit to ground, and prevent the 3.58 MHz trap from operating. This is to prevent the resolution decrease due to the signal RY (B-Y) output and the resolution decrease due to the 3.58 MHz trap.

This will be described in detail with reference to the accompanying drawings.

Horizontal synchronizing signal a resistor (R ₁₎ and a capacitor (C ₁₎ which is the output of the monostable multivibrator (IC ₁₎ is applied to a monostable multivibrator (IC ₁₎ time constant is adjusted in a horizontal blanking period applied by the end The gate AN is configured to be enabled in addition to the horizontal blanking period, and the chroma signal is applied to the chroma signal processing unit 4 and is applied to the non-inverting terminal (+) of the op amp OP ₁ so that the inverting terminal ( The peak value of the chroma signal is output by the capacitor (C ₂ ) and the resistor (R ₂ ) connected to (−) and applied to the inverting terminal (−) of the op amp (OP ₂ ), and the resistance (+) is applied to the non-inverting terminal (+). R ₃ ) and the output of the comparator ₂ including the op amp OP ₂ having the reference voltage set to the variable resistor VR ₁ for improving noise characteristics are configured to be applied to the other side of the AND gate AN.

And the chroma signal processing section (4) between the CMOS switch input of 3.58MHz trap (3), an output terminal for connecting the CMOS switch (IC ₂₎ between the input and ground and outputs a luminance signal receives the video signal of the (IC ₃₎ the output of the AND gate (aN) CMOS switch after configuring connect (IC ₂₎ as soon applied to the N-type gate of the (IC ₃₎ at the same time, the after CMOS switches turn via an inverter _{(I 1) (IC 2)} (IC 3) It is configured to be applied to a P-type gate.

The effect of the present invention configured as described above is divided into a case of a signal having a chroma component and a case of a signal having no chroma component and will be described with reference to each waveform diagram of FIG. 2.

First, the case of a signal with chroma components is described.

That is, the output terminal (Q) of the monostable multivibrator (IC ₁₎ when the separated horizontal synchronizing signal when the signal with a burst signal and a chroma signal applied to the monostable multivibrator (IC ₁₎ as in claim 2a degree A In FIG. 2A, the horizontal blanking period is output at the roll level as shown in FIG.

At this time, in the monostable multivibrator (IC ₁ ), the time constant is adjusted by the resistor (R ₁ ) and the condenser (C ₁ ) according to the horizontal blanking period. Only the blanking period is output at the roll level.

The output of the monostable multivibrator IC ₁ as in B of FIG. 2A is applied to the input side of the AND gate AN so that the AND gate AN is enabled in the calculation other than the horizontal blanking period, that is, the burst Since the AND gate (AN) is not enabled in the period during which the signal comes out (horizontal blank key period), the circuit of the present invention does not affect the dead circuit at this time.

In the chroma signal, the op amp OP ₁ of the peak detection circuit 1 is applied to the non-inverting terminal (+) to obtain the point-to-peak waveform as shown in C of FIG. 2a toward the output side through the diode D ₁ . The peak-to-peak waveform is applied to the inverting terminal (−) of the op amp OP ₂ of the comparator ₂ .

At this time, the operational amplifier so (OP ₂₎ a non-inverting terminal (+), the resistance (R ₃₎ and the reference voltage set by the variable resistor (VR ₁₎ to improve the noise characteristic is applied to the output side of the operational amplifier (OP ₂₎ Compares the two input signals and applies the same signal as in d of FIG. 2a to the input side of the AND gate AN.

Therefore, the AND gate (AN) and the B and D waveforms of Figure 2a (Anding) and outputs the waveform as shown in E of Figure 2a and the output of this (AN) is a CMOS switch (IC ₂ ) (IC ₃ ) ) as soon applied to the N-type gate at the same time, the inverter (I ₁₎ and then the inverted applied doemeurosseo CMOS switch to the P-type gate of the CMOS switch _{(IC 2) (IC 3)} (IC 2) through the (IC ₃₎ are all "off "State.

Therefore, when there is a chroma signal, the chroma coral is input to the chroma signal processing unit 4 and output as the color difference signal RY (BY), while the video signal outputs the luminance signal Y through the 3.58 MHz trap 3. All circuit operations will operate normally to reproduce the color broadcast.

We also look at the case of signals without chroma components.

At this time, since the chroma signal on the non-inverting terminal (+) input side of the op amp OP ₁ of the peak detection circuit 1 is not applied, the output of the peak detection circuit 1 is almost 0 V as shown in FIG. (-) to the inverting terminal of a becomes the output of these peak-to-peak detection circuit (1) outputs the operational amplifier (oP ₂₎ of the so applied to the output side of the operational amplifier (oP _2), thereby outputting the wave as in the 2b-degree D do.

On the other hand, the output of the monostable multivibrator IC ₁ whose time constant is adjusted to the horizontal blanking period is output as shown in B of FIG. 2B and applied to one side of the AND gate AN, and the output of the comparator 2 is of FIG. 2B. Since it is input as in D, the output of the AND gate AN is output as in E of FIG. 2B.

Therefore, the high level output of the AND gate (AN) is a CMOS switch (IC ₂₎ (IC ₃₎ CMOS switch (IC ₂₎ (IC ₃₎ after the reversal as soon applied to the N-type gate at the same time via an inverter (I ₁₎ of The CMOS switch IC ₂ (IC ₃ ) is turned "on" by being applied to the P-type gate.

In this case, when there is no chroma signal, when the CMOS switch IC ₂ (IC ₃ ) is "on", the chroma signal input terminal of the chroma signal processing unit 4 is shorted to ground, and the input and output terminals of the 3.58 MHz trap 3 are shorted. By preventing the normal operation, the resolution resistance caused by the color difference signal RY (B-Y) output and the resolution degradation caused by the 3.58 MHz trap 3 are prevented.

As described above, the present invention determines a color signal and a mono signal as a chroma signal so that when the transmission signal is mono, the signal is reproduced in mono, and when the transmission signal is color, the color signal is reproduced in color. It can switch automatically and does not discriminate color or mono based on the burst signal. When the chroma signal is too small, it can be processed as a mono signal to reproduce clear images. There is an effect that can be made.

Claims (3)

A pulse generator for adjusting the time constant of the horizontal synchronization signal and outputting it in the horizontal blanking period, a peak value detecting circuit (1) for detecting and outputting a peak signal waveform of the chroma signal, and a comparison unit comparing the peak waveform with a reference voltage (2), a logic circuit for controlling the driving of the switching element by combining the outputs of the comparator 2 and the pulse generator, and the driving of the chroma signal processing unit 4 and the filter means by the driving of the switching element is controlled. Black and white signal resolution correction circuit for color broadcasting. The peak detection circuit 1 of claim 1, wherein the peak-to-peak detection circuit 1 applies a chroma signal to a non-inverting terminal (+) of an op amp (OP ₂ ) in which a resistor (R ₂ ) and a capacitor (C ₂ ) are connected to an inverting terminal (-). A black and vaccine resolution correction circuit for color broadcasting configured to input and output peak-peak waveforms. 2. The collar according to claim 1, wherein the filter means is constituted by a 3.58 MHz trap (3) to drive the switching element to the output of a logic circuit that detects when there is no chroma signal to block operation of the 3.58 MHz trap (3). Black, vaccine resolution correction circuit for broadcasting.