JPH0478294A - Transient phenomenon improvement device - Google Patents

Abstract

PURPOSE:To obtain a switching pulse whose S/N is comparatively stable and to match the timing of a luminance signal and a chrominance signal by improving the transient phenomenon of the chrominance signal with a pulse formed by the luminance signal only when the chrominance signal is changed. CONSTITUTION:A signal such as a signal (h) is formed at a differential device 25 from a NON-DELAY signal and a 2-DELAY signal of a color difference signal and a signal (i) is generated by a threshold voltage VC at a comparator 27. Then signals (e), (i) are fed to an AND circuit 29 and signals (f), (i) are fed to an AND circuit 30, and each output is used for a switching signal. The signals (e), (i) are ANDed and when its output is at a high level, a NON-DELAY signal is selected and when both the signals are at a low level, a 1-DELAY signal is selected, then an improved waveform such as a signal (j) is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal processing device for a color television receiver, a video tape recorder, etc., and particularly to a device for improving transient phenomena of a carrier color signal.

[Conventional technology]

FIG. 4 is a diagram showing a conventional color signal contour correction device.

In FIG. 4, 1 is a demodulator 1.2 is a demodulator 2.3 is a low pass filter 1 (hereinafter referred to as LPF 1), 4 is a low pass filter 2 (hereinafter referred to as LPF 2), and 5 is a delay line 1-1. .7 is delay line 1-2.6 is delay line 2-1.8
Delay lines 2 to 2.28 are detectors, 10 is a 3-man power output switch 1.11 is a 3-man power output switch 2.12 is a modulator 1, 13 is a modulator 2, and 14 is an adder.

The carrier color signal input from the 0 color signal input, the operation of which will be explained next, is converted into a color difference signal by demodulators 1 and 2. Note that demodulator 1 and demodulator 2 have a 90°
A carrier wave synchronized with the burst signal of the phase difference carrier color signal is added. Since the color difference signals converted by demodulator 1 and demodulator 2 contain twice as many components as the carrier wave,
Each LPF3. The signal is then removed by the LPF 4 into components twice the carrier wave.

Thereafter, each color difference signal is transferred to delay line 5. Delay line 7 and delay! 6. It is input to delay line 8. It is assumed that these four delay lines each have the same delay amount A. At this time, L
Based on the output of PF, the N0NDELAY signal, I
Three signals are obtained: a DELAY signal and a 2DELAY signal.

These 3 signals are connected to 3 human power 1 output switch 1
Enter 0.11. These switches are controlled by the output of the detector. The outputs of the three single-output switches 10 and 11 are input to the modulator 1213, respectively, and the adder 14
are mixed and returned to the carrier color signal.

FIG. 5 is a diagram specifically explaining the detector shown in FIG. 4.

In the figure, 18 is a differencer 1, 19 is a differencer 2, 20 is an absolute value circuit 1, 21 is an absolute value circuit 2, 22 is a differencer 3, 23 is a comparator 2, and 24 is a comparator 2.

The operation will be explained below. When the N0NDELAY signal, I DELAY signal, and 2DELAY signal are shown as broken lines, solid lines, and dashed-dotted lines in Figure 6 (a), the absolute value is 1.
The output is as shown in Fig. 6 (a). Here, the broken line represents the output of the differentiator 18, and the solid line represents the absolute value taken by the absolute value circuit 20.

FIG. 6(C) shows the output of the absolute value circuit 21 and operates in the same way as the former. Thereafter, the outputs of the respective absolute value circuits 20 and 21 are inputted to the differentiator 22, and a waveform as shown in FIG. 6(d) is obtained. ■ in Figure 6 (b).

■1 is the threshold voltage of comparators 23 and 24, respectively, and as shown in the figure, VA is higher than the center potential, and ■
, is set lower than the center potential. The output of the comparator 23 is Hi when the waveform of FIG. 6(d) is higher than ■, and the output of the comparator 24 is f( when the waveform of FIG. 6(d) is lower than V, Suppose that i is output.

Here, the three-manpower one-output switches io and ii select the 2DELAY signal when the output of the comparator 23 is Hi;
When the output of both is Hi, the NONDELAY signal is selected, and when both are Lo, the IDELAY signal is selected. Therefore, the output of the switch rises as shown in FIG. 6(e).

The falling time is shortened and transient phenomena are improved.

[Problem to be solved by the invention]

The conventional color signal contour correction device is configured as described above, and extracts the transient phenomenon part from the color signal itself to create the switching pulse. Therefore, if the S/N of the color signal is poor, the switching pulse may fluctuate. There are problems such as inaccurate pulses being emitted, switching points being swayed, and ``jaggies'' appearing on the screen.

This invention was made to solve the above-mentioned problems, and it is an object of the present invention to provide a color signal contour correction device in which "jaggies" on a screen are less noticeable.

[Means for Solving the Problems] The transient phenomenon improvement device according to the present invention is capable of: This is to correct the contour of the signal.

[Operation] The transient phenomenon improvement device according to the present invention generally uses a luminance signal with a better S/N than a color signal, so there is less fluctuation in the switching point, and as a result of the improvement, the timing of the luminance signal and the color signal match. do.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure shows a transient phenomenon improvement device according to an embodiment of the present invention,
In the figure, the operations 1 to 13 are exactly the same as in the conventional example, so the means for creating the switch pulse and the detector will be explained.

9 is a detector that generates a signal to control the switch, 15 is a low-pass filter for luminance signal 3.16 is a delay line 3-1.1
7 is a delay line 3-2.

Next, the operation will be explained. The luminance signal input from the luminance signal input is band-limited by the low-pass filter 3 and time-aligned with the chrominance signal. The band of the luminance signal is up to about 5MHz, and the band of the color signal is about 500K.
This is because there is too much difference from Hz, so if a switching pulse is created in the same band as the brightness signal, it will be interposed and no improvement will be made.

The luminance signal then passes through delay line 16 and delay line 17.

Assuming that the delay device of one delay line is A, a signal with no delay (hereinafter referred to as YNONDELAY signal) and an IA delayed signal (hereinafter referred to as YI DELAY signal) with the LPF output as the reference.
2A delayed signal (hereinafter referred to as Y2DEL signal), 2A delayed signal (hereinafter referred to as Y2DEL
AY signals) are obtained, respectively.

FIG. 2 is a diagram specifically explaining the detector shown in FIG. 1.

In the figure, 18 is a differencer 1.19 is a differencer 2.20 is an absolute value circuit 1.21 is an absolute value circuit 2.22 is a differencer 3.23 is a comparator 1.24 is a comparator 2.25 is a differencer The comparator 4.26 has an absolute value of 3.27.

The operation will be explained below. The N0NDELAY signal, IDELA¥ signal, and 2DELAY signal are
) are respectively indicated by a broken line, a solid line, and a - dotted chain line, the output of the absolute value circuit 20 is as shown in FIG. 3 (+)). Here, the broken line represents the output of the differencer 18, and the solid line represents the absolute value taken by the absolute value circuit 20. Figure 3 (C
) is the output of the absolute value circuit 21 and operates in the same way as the former. Thereafter, the outputs of the respective absolute value circuits 20 and 21 are inputted to the differentiator 22, and a waveform as shown in FIG. 3(d) is obtained.

Va and Vg in FIG. 3(d) are the threshold voltages of the comparators 23 and 24, respectively, and as shown in the figure, 1 is set higher than the center voltage, and 2 is set lower than the center potential. The output of the comparator 23 has the waveform shown in Fig. 3 (cl).
, outputs Hi when HiO.

This is shown in FIG. 3(e). The output of the comparator 24 is the third
It is assumed that when the waveform in Figure (e) is Lo than ■1, a Hi signal is output. This is shown in Figure 3). The luminance signal changes more than the chrominance signal, and if it is switched with a pulse made only from the luminance signal (Fig. 3 (e), line), it will cause a malfunction. N0N
Using the DELAY signal and the 2DELAY signal, a signal as shown in FIG. Here, the fact that there is no change in the signal on the right side of the signal (g) indicates that only the luminance signal (a) has changed and the color signal (g) has not changed.

Next, the (e) signal and (i) signal are sent to the AND circuit 29, and (f
) signal and (i) signal are input to the AND circuit 30, and their respective outputs are used as switching signals. (e) signal and (i)
AND the signal and when the output is Hi, N0NDELA
By taking the Y signal and selecting the IDELAY signal at 00 o'clock, an improved waveform as shown in (j) can be obtained.

In other words, according to this embodiment, the transient part of the color signal is extracted,
Transient phenomena can be improved using the switching pulse created by the luminance signal only when the color signal is changing, so the switching point is stable and color contour correction can be performed without "jaggies" appearing on the screen. can be done.

〔Effect of the invention〕

As described above, according to the transient phenomenon improvement device according to the present invention, since the transient phenomenon of the color signal is improved by the pulse generated by the luminance signal only when the color signal is changing, A more stable switching pulse can be obtained than a luminance signal with a relatively good S/N ratio, there is less jaggedness at the color change, and malfunctions that occur due to the use of luminance signals can be prevented, and the timing of the luminance signal and color signal can be matched. It has the effect of

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a transient phenomenon eye opening device according to an embodiment of the present invention, Fig. 2 is a diagram illustrating the detector in Fig. 1 in detail, and Fig. 3 is a diagram for explaining the operation of Fig. 2. Figure 4 is a diagram showing the conventional transient phenomenon improvement device, Figure 5 is the waveform diagram of
FIG. 6 is a diagram explaining the detector in detail in detail, and FIG. 6 is a waveform diagram for explaining the operation of FIG. 5. In the figure, l is a demodulator 1.2 is a demodulator 2.3 is a low-pass filter 1.4 is a low-pass filter 2.5 is a delay line 1-1.7 is a delay line 1-2.6 is a delay line 2-1 .8 is the delay line 2-2.28 is the detector, lO is the 3-manpower 1-output switch 1.11 is the 3-manpower 1-output switch 2.12 is the modulator 1.13 is the modulator 2.14 is the adder, 9 15 is a low-pass filter for brightness signals. 16 is a delay line 3-1. 17 is a delay line 3-2.
．． 29.30 is an AND circuit. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A device for improving the transient phenomenon of a carrier color signal, comprising: a first delay means for delaying the input color difference signal for a predetermined time; and a second delay means for delaying the input color difference signal for a time longer than the first delay time. a delay means; a third delay means for band-limiting the input luminance signal and then delaying the input luminance signal for a predetermined time; and a fourth delay means for delaying the band-limited input luminance signal for a time longer than the third delay time. , means for calculating the absolute value A of the amplitude difference between the band-limited input luminance signal and the output signal of the third delay means, and the output signal of the third delay means and the output of the fourth delay means. The means for calculating the absolute value B of the amplitude difference with the signal compares the magnitude of the above two absolute values A and B, and selects the above input color difference signal during the period when A<B, and when A=B. 1st above
means for selecting the output signal of the delay means, and selecting and outputting the output signal of the second delay means during the period A>B; and means for selecting and outputting the output signal of the second delay means; A means for calculating the absolute value C of the amplitude difference, a means for comparing whether the absolute value C is larger or smaller than a certain level, and when it is large, the above selection result is output, and when it is small, it is always
and means for outputting an output signal of the delay means.