KR890004983Y1 - Chrominance signal compensate circuit - Google Patents

Abstract

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Description

Transient Response Characteristics of Color Difference Output Signals

1 is a block diagram of a conventional color reproduction circuit.

2 is a block diagram of a color reproduction circuit of the present invention.

3 is a transient response characteristic improvement circuit of FIG.

4 is an output waveform diagram of each part of FIG.

* Explanation of symbols for main parts of the drawings

B ₁ , B ₂ : Butter SW ₁ : Electronic switch

A, C: High pass filter B: Full-wave rectifier

CM ₁ : Comparator

The present invention relates to a transient response characteristic color quality compensation circuit of a color difference output signal capable of compensating for the color quality by accelerating the transient response characteristic of the color difference signal output from all color reproduction circuits.

In general, as shown in FIG. 1, the color reproduction circuit includes the color difference signals RY, GY, and the like, which are output from each of the demodulators 11, 12, and 13 of the color difference signal demodulator 1; (BY) is applied to each of the output sections 31, 32, and 33 of the matrix circuit section 3, and the y-signal Y output from the image amplification section 2 is the matrix circuit section 3, respectively. The color signals R, G, and B are output from the output sections 31, 32, and 33 by being applied to the output sections 31, 32, and 33 of the The color signals R, G, and B were applied to the electron gun of the CRT 4 and displayed.

However, in such a conventional circuit, since the transient characteristics of each passenger signal output from the chrominance signal demodulation unit 1 are not good, the living interface (white, yellow, cyan, green, magenta, red, blue, etc.) It was not clearly distinguished, and in particular, this phenomenon had the drawback of appearing more severely on still images than on moving images.

In view of this point, the present invention improves the transient response characteristics of each color difference signal output from the color difference signal demodulation unit so that the color boundary can be clearly distinguished, which will be described in detail with reference to the accompanying drawings. same.

2 is a block diagram of a color reproduction circuit according to the present invention, wherein each of the demodulators 11, 12, and 13 of the color difference signal demodulator 1 and the output units 31 of the matrix circuit unit 3 are described. The transient response characteristic improvement circuits 51, 52, and 53 are connected to each other between (32), (33), and the transient response characteristic improvement circuits (51), (52), (53). Is configured in the same manner as shown in FIG.

That is, the third also color-difference signal output terminal through a buffer (B _1), the electronic switch (SW _1), a ground capacitor (C ₁₎ and a buffer (B ₁₎ a color difference signal input terminal (IN) as shown in ( OUT, but the output side of the buffer (B ₁ ) is a high pass filter (A) consisting of a capacitor (C ₂ ) and a resistor (R ₁ ), an inverter (I ₁ ) and a diode (D ₁ ), (D ₂ ) based on the inverting input terminal (-) through a full-wave rectifier (B) composed of a capacitor, a high pass filter (C) composed of a capacitor (C ₃ ) and a resistor (R ₂ ), and a ground diode (D ₃ ) The non-inverting input terminal (+) of the comparator CM _{1 to} which the voltage Vref is applied is connected, and the output terminal of the comparator CM ₁ is connected to the control terminal of the electronic switch SW ₁ . Each color difference signal input terminal IN of each of the transient response characteristic improvement circuits 51, 52, and 53 is provided at the outputs of the demodulators 11, 12, and 13 of the color difference signal demodulator 1, respectively. Connected to the color difference signal output terminal OUT. Each output switch 31 of the circuit 3, 32, are respectively connected to the input side of the CPU 33.

In addition, the electronic switch SW ₁ remains open in the initial state, and when the high potential signal is applied and falls to the low potential signal, the electronic switch SW ₁ is short-circuited and then the high potential signal is applied to the low potential signal. It is supposed to be open.

Referring to the effects of the present invention configured in this way in detail as follows.

When the color difference signal is applied to the color difference signal input terminal IN and the color difference signal as shown in FIG. 4 (a) is output to the output side of the buffer B ₁ , the transient characteristic period (t ₁ -t ₂ ) of the output signals is output. ) Signal through the high pass filter (A) and then through the diode (D ₁ ) of the full-wave rectifier (B). Thereafter, while the color signal is kept constant, no signal is passed through the high pass filter A, and the waveform signal as shown in FIG. 4 (b) is output to the output side of the full-wave rectifier B. FIG. That is, during the transition period (t ₁ -t ₂ ) where the color difference signal increases, a high potential signal is output to the output side thereof by the diode D ₁ of the full-wave rectifier B, and then while the color difference signal is kept constant ( t _2- t ₃ ) has no signal through the high pass filter (A), so that the low potential signal is output to the output side of the full-wave rectifier (B), and then during the transient period when the color difference signal is reduced (t ₃ -t ₄ ). The high potential signal is output by the inverter I ₁ and the diode D ₂ of the full-wave rectifier B.

In this way, the signal output from the full-wave rectifier (B) passes through the high pass filter (C) again, so that the waveform signal as shown in FIG. ₁ ) is applied to the non-inverting input terminal (+).

Accordingly, the signal applied to the non-inverting input terminal (+) of the comparator CM ₁ is compared with the reference voltage Vref applied to its inverting input terminal (-) and is shown in FIG. A square wave signal as shown is output, and this output signal is applied to the control terminal of the electronic switch SW ₁ to control it.

That is, the output side of the electronic switch (SW ₁₎ is a signal the high potential at the output of the comparator (CM ₁₎ while keeping the open state to the initial state, the output is connected to it it falls to a low potential state, since a comparator (CM ₁₎ It opens when the high potential signal is output again and falls to the low potential state.

Accordingly, the color difference signal through the buffer (B ₁₎ is the fourth that the electronic switch (SW ₁₎ and a buffer so placed through (B ₂₎ a color-difference signal output terminal (OUT) when the electronic switch (SW ₁₎ is short-circuited ( e) A color difference signal as shown in the figure is output.

As can be seen from the waveform diagram of Fig. 4 (e), the initial transient response characteristic of the color difference signal is shortened from the time t ₁ -t ₂ to the time t ₂ -t _{2 '} and the late transient response characteristic of the color difference signal This time is greatly shortened from time t ₃ -t ₄ to time t _{3 '} -t ₄ .

As described above, the present invention has an advantage that the color difference signal can be clearly distinguished since the transient response characteristic time is greatly shortened.

Claims (1)

The color difference signal output terminal IN is connected to the color difference signal output terminal OUT through the buffer B ₁ , the electronic switch SW ₁ , the ground capacitor C ₂ , and the buffer B ₂ , but the buffer B ₁ ) the output side of the high pass filter (A) consisting of a capacitor (C ₂ ) and a resistor (R ₁ ), a full-wave rectifier (B) consisting of an inverter (I ₁ ) and diodes (D ₁ , D ₂ ), A high pass filter C consisting of (C ₃ ) and a resistor (R ₂ ) and a ground diode (D ₃ ) are sequentially applied to a non-inverting input terminal of a comparator (CM ₁ ) to which a reference voltage is applied to the inverting input terminal. And an output terminal thereof connected to a control terminal of the electronic switch (SW ₁ ).