JPS6377290A - Hue variable circuit - Google Patents

Abstract

PURPOSE:To attain the video reproduction of any primary color with an optimum hue by generating two color difference signals from a primary color signal, making the hue variable with a variable gain circuit and a hue variable circuit composed of subtracting and adding circuits and converting them to the primary color signal. CONSTITUTION:Variable gain circuits 3-6 can make a gain variable with the control signal of cosine sine signal generating circuits 9 and 10 which are control signals, and therefore, the signal is obtained in which the output of the circuits 3 and 6 is sintheta-folded and the output of circuits 4 and 5 is costheta- folded. When color difference signals R-Y and B-Y are inputted to input terminals 1 and 2, the outputs of circuits 3 and 4 come to be (R-Y) sintheta, (R-Y) costheta, and the outputs of circuits 5 and 6 come to be (B-Y)costheta and (B-Y)sintheta. The output of an adding circuit 7 comes to be [(R-Y) costheta+(B-Y)sintheta] and the output of a subtracting circuit 8 comes to be [(B-Y)costheta-(R-Y)sintheta]. When these outputs are converted to an RGB signal with a matrix circuit, the hue of the primary color signal can be variable.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is capable of varying the hue of a demodulated color difference signal of a color television signal and a color difference signal generated from red, green, blue (RGB) primary color signals. This paper relates to a variable color difference circuit that makes it possible.

(Prior art and its problems) Color television receivers are capable of adjusting the hue of both sides according to viewing conditions or preference.

A hue variable circuit for adjusting the hue is generally provided before color demodulation.

Therefore, in recent years, television receivers are increasingly being used not only to receive only the transmitted waves, but also as monitors and displays for other equipment, such as video tape recorders, video disks, computers, and the like.

The signals supplied to the television receiver from these other devices are RF multiplied signals or primary color signals of red, green, and blue (hereinafter sometimes referred to as RGB). However, with conventional hue variable circuits, it is not possible to vary the hue of the RGI3 primary color signal.
There has been a need for a hue variable circuit that can vary the hue of GB primary color signals.

(1,000 yen to solve the problem) In order to solve the above problem, the present invention aims to
first and second variable circuits to which a color difference signal (R-Y) of the video signal is supplied, and a second color difference signal (B-Y) of the video signal;
Y) is supplied with a third variable gain circuit, I'j and a fourth variable gain circuit, and a third variable gain IT? A subtraction circuit that sends out a difference signal between the output signals of the first variable gain circuit and an addition circuit that sends out a sum signal of the respective output signals of the second and fourth variable gain circuits from the output signal of the second variable gain circuit. , a variable voltage source that generates a control DC voltage
a sine signal generation circuit that sends out a control signal of f (x) to control the gain of the first and fourth variable gain 19 circuits; The present invention provides a variable hue circuit characterized in that it includes a cosine signal generating circuit that controls the gain of the second and third variable gain circuits.

(Example) First, the basis of the invention of the hue variable circuit of the present invention will be explained with reference to FIG. 2, which is an explanatory diagram.

If the amplitude of the quadrature two-phase modulated carrier color signal is X, the luminance signal is Y, and the phase angle is θ, then the color difference signal (R-Y), (B
The demodulated signal of -Y) has a relationship as shown in FIG. 2, that is, the following m, equation (2) holds true.

R-Y-Xsin a ・(11B-Y
＝ It can be expressed by equations (3) and (4).

(RY)' = Xsin <a+θ)-Xsin
αcO8θ〒XCO3αS1nθ ・(3)(B-Y
)' =Xcos (α10)-X cos a c
osθ−Xsin αsinθ ・(4i above +3)
, Substitute equations (1) and [2) into equation [4] to obtain the following (5)
, '6) formula is obtained.

(RY)' - (RY)cos θ+(B-Y
) sin θ ゛(51(
B-Y)' = (B-Y)cas θ(R-
y) sin θ・(6)
Above (5), ! When transferring the baseband color difference signal from Equation 61, the color difference signal (R-Y)' is the input color difference signal <R-Y) and <B-Y), respectively.
The color difference signal (B
-Y)' is the input color difference signal (B-Y), (R-Y
) is multiplied by CO3θ and sinθf8, respectively, and then subtracted.

The hue variable circuit of the present invention is made based on the above principle, and a block system diagram of one embodiment thereof is shown in 1F. In the figure, 1 and 2 are input terminals to which color difference signals are supplied. The signal supplied to this input terminal 1 is
is supplied to each of 19 externally controllable variable gain circuits 3.4. 85,
6 are supplied to each of them.

The variable gain circuit 4.5 receives an output signal from the cosine signal generation circuit 9 for controlling the gain.
．． 6 are each supplied with an output signal from a sine signal generating circuit 10 for controlling the gain.

The cosine signal generating circuit 9 and the sine signal generating circuit 10 are supplied with the DC voltage X from the variable voltage source 13 as a control signal, thereby generating CO3f (x), respectively.

A control signal expressed as sin f (x) is generated.

Furthermore, the output signals of the variable gain 1q circuits 4 and 6 are added to the adder circuit 7.
The output signals of the variable gain circuit 3.5 are respectively supplied to the two input terminals of the subtraction circuit 8, and the output signals of the addition circuit 7 and the subtraction circuit 8 are supplied to the output terminal 1.
1.12 respectively.

Next, the operation of the hue variable circuit of the present invention having such a configuration will be explained.

The variable gain circuits 3 to 6 are composed of, for example, well-known double-balanced amplifier circuits, and the gain thereof can be freely varied by an external abrasion control signal. Since the circuit 9 and the sine signal generation circuit 10 each have a relationship of sin θ and COS θ, the output signal of the variable gain circuit 3.6 is multiplied by sin θ, and the output signal of the variable gain circuit 19 4°5 is A signal multiplied by COS θ will be obtained.

Therefore, when the color difference signal (R-Y) is supplied to the input terminal 1, the output of the variable gain circuit 3.4 has the sign (R-Y), respectively.
Y) sin θ, (RY) becomes a signal multiplied by cos θ. On the other hand, when the color difference signal (B-Y) is supplied to the input terminal 2, the output signals of the variable gain circuits 5 and 6 become signals multiplied by (B-Y) cos θ and (B-y > sin θ), respectively.

Therefore, the output signal of the adder circuit 7 is E (RY)COS
o + (B-Y) sin θ] times the signal, and the output signal of the subtraction circuit 8 is [(B-Y) cos 0-(R-Y
) sin θ times the signal.

As described above, the embodiment of FIG. 1 is a circuit that satisfies the above-described equations (5) and (6), and a hue variable circuit for a desired color difference signal can be obtained.

(Effects of the Invention) According to the present invention, from the RGB primary color signals, (RY), (
By creating a color difference signal (B-Y), changing the hue of these two color difference signals using the hue variable circuit of the present invention, and then converting it into an RGB signal using a matrix circuit, it is possible to change the hue of the RGB primary color signals. , RGB supplied externally
It has the advantage of being able to reproduce video with the optimum hue even with primary color signals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the hue variable circuit of the present invention, and FIG. 2 is a diagram for explaining the present invention in detail. 1.2...Input terminal, 3~G...Variable gain circuit, 7
... Addition circuit, 8...5! calculation circuit, 9... cosine signal ordering circuit, 10... sine signal generation circuit, 11.12
...Output terminal, 13...Variable voltage source, ×...Sub-part DC voltage. Patent applicant: Victor Japan Co., Ltd. -・2゛pa... Representative: Kunio Umiki +, ゛2. ;F Figure 1 Figure 2

Claims (1)

[Claims] The first color difference signal (RY) of the video signal is supplied.
and a second variable gain circuit, third and fourth variable gain circuits to which the second color difference signal (B-Y) of the video signal is supplied, and a first a subtraction circuit that sends out a difference signal between the output signals of the variable gain circuit;
An adder circuit that sends out a sum signal of the respective output signals of the second and fourth variable gain circuits, a variable voltage source that generates a control DC voltage x, and a control signal of sinf(x) using this control voltage x. a sine signal generating circuit that controls the gains of the first and fourth variable gain circuits by controlling the gains of the first and fourth variable gain circuits; A hue variable circuit characterized by comprising a cosine signal generating circuit for controlling the hue.