JPS6236994A - Device for automatically correcting hue - Google Patents

Abstract

PURPOSE:To attain accurate color correction even if variation in ICs exists by inserting an adjusting means adjusting the level of a color difference signal fed to a composite circuit between a demodulation circuit and the synthesis circuit. CONSTITUTION:When a R-Y color difference signal is generated at an output terminal 13 of a demodulating circuit 12 and a B-Y color difference signal is generated at an output terminal 15, a Q signal is generated at an output terminal of the 1st composite circuit 16. The signal is deviated from the Q axis toward the R-Y axis. In this case, a slider of the 2nd variable resistor 23 is placed at the lowermost position and the slider of the 1st variable resistor 21 is adjusted, then a part of the attenuated R-Y color difference signal and B-Y color difference signal to the input terminal 22 of the circuit 16 and the B-Y color difference signal is applied as it is to the input terminal 12, then the output signal of the circuit 16 becomes a signal Q', which is coincident with the Q axis. When the axis is deviated toward the B-Y axis, the slider of the resistor 21 is placed to the uppermost position and the slider of the resistor 23 is adjusted, then the output signal of the circuit 16 becomes the signal Q', which is coincident with the Q axis. Thus, the deviation is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an automatic hue correction device for a color television receiver that can automatically correct the hue.

(B) Prior Art An automatic hue correction device that automatically corrects hue has already been filed as Japanese Patent Application No. 60-50869 by the same applicant as the present application. The device is as shown in FIG. 3, and the composite video signal applied to the input terminal (1) is
The signal is amplified by a band amplification circuit (2) and a second band amplification circuit (3), and separated into a chroma signal and a burst signal by the second band amplification circuit (3). The chroma signal is then applied to a demodulation circuit 0 to be demodulated, and the burst signal is applied to a phase comparator (5) to be used to create a CW (local subcarrier) signal and an ice (auto chroma) signal. control) circuit (4) and used for gain control.

The phase comparator (5) is connected to the PLL together with VCOf61.
The burst signal and the ■Co
(Since the phase comparator (5) compares the phase of the output signal of VCOt61, a 1-CW signal is generated at the output terminal of VCOt61 in synchronization with the burst signal.

The CW multiplied signal is applied to the first and second phase shift circuits aα and Uυ via the hue adjustment circuit (9). 1st and 2nd
The phase shift circuits Ql and 01) have the CW multiplied signal phases φ1 and φ, respectively, and the deviations fscW 肚-y signal and CWs-v
Generate a signal. and the CW irises-v signal and the CWI
By applying the -Y signal to the demodulation circuit 02, the R-Y color difference signal and the B-Y color difference signal are demodulated, respectively. Furthermore, by matrixing the demodulated R-Y color difference signal and the B-Y color difference signal, a Jx-Y color difference signal is obtained.
The Y color difference signals are the first . 2nd and 3rd output terminal 0
31, Q4) and 05) to the subsequent stage and used for color reproduction.

The R-Y color difference signal obtained at the first output terminal 0□□□ and the third
The B-Y color difference signal obtained at the output terminal 0 is synthesized by the first synthesis circuit OQ, and a Q signal is generated at the output terminal. The Q signal is amplified on the amplifier circuit side and supplied as an adjustment signal to the average adjustment circuit (a). The average adjustment circuit (21) smoothes the adjustment signal and supplies it to the hue adjustment circuit (9) as an average adjustment signal.The R-Y color difference signal and the B-Y color difference signal are 2 is applied to the synthesis circuit OD, and the R-Y color difference signal and the inverted B
-Y color difference signals are combined, and an I signal is generated at the output terminal of the second combining circuit 0η. Then, the I signal is transmitted to the control circuit α
(2), and the reference signal (Vref) is applied to the control circuit OI.
compared to Now, if the level of the ■ signal is higher than the level of the reference signal, a control signal is generated from the control circuit OI, and the amplifier circuit (1) becomes operational and amplifies the Q signal. to generate the adjustment signal.

Then, the adjustment signal is averaged by an average adjustment circuit,
The signal is supplied to the hue adjustment circuit (9).

On the other hand, if the level of the I signal is lower than the level of the reference signal, the control signal is not generated and the amplifier circuit 0 mark does not operate, so that automatic hue correction is not performed.

Next, the automatic hue correction operation will be explained. If there is a chroma signal that is deviated by α degree from the ■ axis shown by A in FIG. 4, the level of the Q signal will be B, and the level of the ■ signal will be C. The level C of the above ■signal is set as a reference signal (V r
ef ), the Q signal is amplified by the amplifier circuit, smoothed by the average adjustment circuit (1), and applied as an average adjustment signal to the hue adjustment circuit (9). When the average adjustment signal is applied to the hue adjustment circuit (9), the CW multiplied signal phase rotates according to the level of the average adjustment signal, and the first and second phase circuits (0I and OLD) rotate accordingly. The phases of the output signals CWl-T and CWm-Y are also rotated. This means that the demodulation axis rotates in the demodulation circuit 04, and as shown in FIG.
It rotates by degrees to become the (R-Y) axis, and the B-Y axis is also rotated by α degrees to become the (B-Y) axis. In this case, since the Q signal is created from the R-Y color difference signal and the B-Y color difference signal, the I-axis and Q-axis also rotate according to the rotation of the demodulation axis.
When the correction is completed, the chroma signal A overlaps the I axis, and the level of the Q signal becomes zero. In other words, this automatic correction rotates the demodulation axis so that the level of the Q signal becomes small.

Automatic hue correction is performed only when there is an I signal of a predetermined level or higher. Therefore, automatic hue correction is performed only when the chroma signal exists near the I-axis, that is, near the skin color.

Further, automatic correction of hue is performed according to the level of the Q signal, and when the Q signal is dog, a large correction is performed, and when it is small, a small correction is performed, so the automatic correction is performed depending on the level of the Q signal. It will only be relevant.

l/1 Problems to be Solved by the Invention The circuit of FIG. 3 is used as a demodulator circuit 021. The phase shift circuit (101 and old) and hue adjustment circuit (9) are built into ICI, the first and second synthesis circuits and a, and the control circuit α■ and amplifier circuit 08 are built into IC2. In the case of integration (wr), there are many types of ICIs, each with a different demodulation angle and demodulation ratio. Moreover, even in the case of the same IC, it changes due to variations. The same applies to the first synthesis circuit of IC2. Therefore, the Q signal obtained by combining the RY color difference signal and the BY color difference signal may not match on the Q axis, and correct correction cannot be performed. Therefore, it is necessary to align the Q signal on the Q axis, but if the first synthesis circuit is built into an IC, there is a problem that adjustment cannot be performed.

The present invention has been made in view of the above points, and includes a demodulation circuit and a synthesis circuit that synthesizes a Q signal using a color difference signal obtained at the output terminal of the demodulation circuit. An adjusting means for adjusting the magnitude of the applied color difference signal is inserted between the two.

(E) Effect According to the present invention, the levels of the two color difference signals applied to the synthesis circuit are adjusted by a variable resistor so that the Q signal coincides with the Q axis. etc., accurate hue correction can be performed.

(F) Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which one end of Qυ is connected to the first output terminal 0 of the demodulation circuit n'lI, and the movable terminal is connected to the One end is connected to the other end of the first variable resistor (21), and the other end is connected to the third input terminal of the demodulator circuit (21).
This is a second variable resistor connected to the output terminal (l (g)) and whose movable terminal is connected to the second input terminal H of the first composite circuit OD. are given the same figure numbers and the explanation will be omitted.

As shown in FIG.
If a color difference signal is generated, a Q signal is generated at the output terminal of the first combining circuit Q61. This Q signal is from the Q axis to R-
Since it is shifted in the Y-axis direction, it must be corrected. In that case, by positioning the movable terminal of the second variable resistor Q3) at the lowest end and adjusting the movable terminal of the first variable resistor (21), the attenuated Part of the R-Y color difference signal and the B-Y color difference signal are applied, and the B-Y color difference signal is directly applied to the second input terminal C24) of the first combining circuit αQ, so that the first combining circuit 06 ) output signal becomes Q as shown in FIG. 6, and coincides with the Q axis. Therefore, the output signal of the first combining circuit 00 is R
- If there is a deviation in the Y-axis direction, the deviation can be corrected by adjusting the first variable resistor (21) as described above. To check the correction, check the chroma signal that corresponds to the correct skin tone.
This is achieved by applying the voltage to the demodulation circuit α, connecting a voltmeter to the output terminal of the amplifier group, and adjusting the first variable resistor Qυ so that the reading becomes zero.

On the other hand, as shown in FIG. 7, if the R-Y color difference signal is generated at the first output terminal (13) of the demodulation circuit (12) and the B-Y color difference signal is generated at the third output terminal 0ω, then the first Synthesis circuit (1
A Q signal is generated at the output terminal of 0. Since this Q signal deviates from the Q axis in the B=Y axis direction, it must be corrected. In that case, by positioning the movable terminal of the first variable resistor (21) at the uppermost end and adjusting the movable terminal of the second variable resistor (23), the first input terminal (221
The R-Y color difference signal is applied as is, and the second
Attenuated B-'YY color difference signal R- to input terminal C4)
Since a part of the Y color difference signal is applied, the first synthesis circuit Oe
As shown in FIG. 7, the output signal becomes Q and coincides with the Q axis. Therefore, if the output signal of the first combining circuit OQ deviates in the BY-axis direction, the deviation can be corrected by adjusting the second variable resistor 0 as described above.

FIG. 2 shows another embodiment of the present invention, in which one end of the first variable resistor (21) is connected to the first output terminal H of the demodulation circuit (12).
and the other end is grounded, and one end of the second variable resistor (c) is connected to the third output terminal 09 of the demodulator circuit Q.
The other end is grounded.

As shown in FIG. 8, the demodulation circuit (+21 first output terminal (
If an R-Y color difference signal is generated at the first output terminal and a B-Y color difference signal is generated at the third output terminal 0, the first synthesis circuit Qf
A Q signal is generated at the output terminal of 9. Since this Q signal deviates from the Q axis in the RY axis direction, it must be corrected. In that case, by adjusting the movable terminal of the first variable resistor H and positioning the hook terminal of the second variable resistor (2) at the top end, the first input terminal (C) of the first composite circuit 0e Since the attenuated R-Y color difference signal is applied and the B-Y color difference signal is directly applied to the second input terminal Ci'4) of the first combining circuit (16), the first combining circuit (16) The output signal becomes Q as shown in FIG. 8 and coincides with the Q axis. Therefore, if the output signal of the first synthesis circuit OQ deviates in the RY axis direction, the deviation can be corrected by adjusting the first variable resistor (2υ) as described above.

On the other hand, as shown in FIG. 9, the first output terminal 0 on the demodulation circuit side
:1 has the R-Y color difference signal, and the third output terminal (one has the B-Y color difference signal
If a color difference signal is generated, a Q signal is generated at the output terminal of the first combining circuit OQ. This Q signal is from the Q axis to B-Y
It is axially misaligned and must be corrected.

In that case, by positioning the movable terminal of the first variable resistor (2I) at the top end and adjusting the movable terminal of the second variable resistor (2I), the first input terminal (221) of the first combining circuit (16) ,R
-Y color difference signal is applied as is, and the attenuated B color difference signal is applied to the second input terminal 0141 of the first synthesis circuit (16).
Since the -Y color difference signal is applied, the output signal of the first synthesis circuit QB) becomes Q as shown in FIG. 9 and coincides with the Q axis. Therefore, if the output signal of the first synthesis circuit deviates in the BY-axis direction, the deviation can be corrected by adjusting the second variable resistor C (as described above).

(g) Effects of the Invention Therefore, according to the present invention, the output signal of the first combining circuit can be adjusted by adjusting the two variable resistors, and the output signal can be correctly aligned with the Q axis. Also, the conventional I
By simply connecting an external variable resistor to C, the level of the color difference signal is adjusted to match the output signal of the first synthesis circuit with the Q axis, so there is no need to increase the number of pins on the IC (see above). Adjustments can be made.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the present invention, FIG. 3 is a circuit diagram showing a conventional hue automatic correction device, and FIGS. FIG. 5 is a vector diagram for explaining the operation of FIG. 3, and FIGS. 6, 7, 8, and 9 are vector diagrams for explaining the present invention. Explanation of main drawing numbers (9)...hue adjustment circuit, 02...demodulation circuit,
(1(D...first composite circuit, (2I)...first variable resistor, ■3)...second variable resistor. Applicant Sanyo Electric Co., Ltd. and one other representative Patent attorney Shizuka Sano Husband: RY axis α!- B-Y!m

Claims (1)

[Claims] An automatic hue correction device having a synthesis circuit for synthesizing a Q signal using a color difference signal obtained at an output end of a demodulation circuit, and automatically adjusting a hue adjustment circuit according to the output signal of the synthesis circuit, An automatic hue correction device characterized in that an adjustment means for adjusting the magnitude of the color difference signal applied to the synthesis circuit is inserted between the demodulation circuit and the synthesis circuit.