JPS63198497A - Color encoder - Google Patents

Abstract

PURPOSE:To eliminate time phase difference between a luminance signal and a chroma signal by supplying a luminance signal to an adder via a delay circuit. CONSTITUTION:Three primary color signals supplied to respective terminals R, G, B are converted into a chroma signal consisting of a luminance signal Y, and color difference signals R-Y, B-Y by a matrix circuit 11 and outputted therefrom. The chroma signals R-Y and B-Y are supplied to modulation circuits 12, 13, and modulated on carrier waves outputted from an oscillator 14 and having different phases by 90 degrees by a 90-degree phase shifter 15, thereafter weighted in weight circuits K1, K2 to a necessary extent, and are supplied to an adder 16. A chroma signal outputted from the adder 16 is inputted to an adder 18 via a BPF 17. On the other hand, a luminance signal Y from the circuit 11 is delayed by a delay circuit 19 to have the same delay as the chroma signal, and inputted to the adder 18. By supplying a color burst signal and a synchronizing signal to the adder 18, a VBS signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color encoder that adds a luminance signal and a chroma signal via a signal processing circuit to an adder.

(Prior Art) The configuration shown in FIG. 13 is known as a color encoder used in NTSC color television broadcasting.

R (RED), G (GREEN).

The primary color signals applied to each terminal of B (BLLJE) are
The matrix circuit 1 generates a luminance signal (Y signal) and R-
It is converted into a chroma signal (C signal) consisting of Y and BY color difference signals and output.

Of these, the (R-Y) and (B-Y) signals, which are chroma signals, are both applied to modulation circuits 2 and 3, generated by an oscillator 4, and generated by a 90' phase shifter 5 to produce different colors with a 90'' phase shift. After being modulated into a carrier wave, the signal is weighted as necessary by weighting circuit Kt2, and then added to adder 6.

Further, the chroma signal output from the adder 6 passes through a bandpass filter 7 having the center frequency of the color carrier wave, and is added to the adder 8 together with the luminance signal. In addition to both signals, a color burst signal and a synchronization signal are added to the adder 8 to generate a VBS signal (Video Burst signal).
5ync, ) is output. This VBS signal is
etc. can be added.

By the way, in such a configuration, when observing the luminance signal and chroma signal output from the matrix circuit 1, there is a difference of 80 to 100 nS between the two signals input to the adder 8.
A time phase difference can be seen. This is because the paths of both signals from matrix circuit 1 to adder 8 are different, and modulator 2
, 3, etc., the chroma signal is delayed from the luminance signal. Figure 14 (a), (b), (
c) is a timing chart showing this situation, and the timing chart shown in FIG.
The output luminance signal for the input signal is shown in Fig. 14 (
Although there is almost no delay as shown in b), the output chroma signal is T (80 to 100) as shown in Fig. 14 (C).
ns), and a time phase difference occurs between the luminance signal and the chroma signal.

The existence of a time phase difference between the two signals means that the V
When playing back a video recorded with a BS signal, the image quality will be adversely affected. Figures 5(a) to (d>) show output signals when video is reproduced in this way via a color decoder, where Figure 15(a> is a Y signal and Figure 15(b) is a Y signal. RY signal, FIG. 15(C) shows the G-Y signal, and FIG. 15(d) shows the BY signal.

Here, Y is the average value of the R, G, and B outputs of the decoder,
It is shown as follows.

Y= (RDEC+GDEC+BDEC>/3, that is, R-Y, G-Y, B-Y are R, G, B of the decoder
It is obtained by subtracting Y from the output, and shows the change in R2O,B with respect to white.

As is clear from the figure, a time phase difference occurs between the Y signal representing the luminance signal and the RY, G-Y, and BY signals representing the chroma signal due to the influence of the color encoder. At the same time, the levels of the color signals in FIGS. 15(b) to 15(C) have decreased, meaning that most of the color information has been lost, and only the brightness is reproduced.

Such color encoders are applied to medical equipment such as color cameras, ultrasonic diagnostic devices, and endoscope devices. Particularly in ultrasound diagnostic equipment, characters are used to improve diagnostic effectiveness, unlike images for general television broadcasting.

Steep pulse-like signals such as markers and dots are used, and the pulse widths of these signals are set as short as 65 to 8 Qns. Time phase difference between both signals of color encoder 8
0 to 100ns is horizontal pixel 1P of ultrasound diagnostic equipment
This value corresponds to iX (vixels).

For this reason, especially in ultrasonic diagnostic equipment,
Although they can be displayed on a color monitor using RGB signals, they are recorded on a VTR.

When it comes to reproduction, it is difficult to reproduce colors.

For example, even if there is no time phase difference in the VTR recording and playback monitor display paths, as long as a color encoder is used, the dots on the monitor will have no color due to the time phase difference between the two signals, as shown in Figure 16, for example. As shown in the figure, only a small amount remains in the diagonally shaded area on the right side.

<Problems to be Solved by the Invention> As described above, in conventional color encoders, there is a problem in that there is a time difference between the luminance signal and chroma signal that are output from the matrix circuit and input to the adder. .

The present invention was made in response to such problems, and it is an object of the present invention to provide a color encoder that eliminates the time phase difference that exists between a luminance signal and a chroma signal.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention is characterized in that a luminance signal is applied to an adder via a delay circuit.

(Function) The chroma signal output from the matrix circuit is input to the adder via a signal processing circuit such as a modulation circuit, and the luminance signal is input to the adder via a delay circuit. As a result, the time phase of the luminance signal can be delayed by the amount that the chroma signal is delayed in time phase through the signal processing circuit, so that the time phase difference between the two signals can be eliminated.

(Embodiment) FIG. 1 is a block diagram showing a color encoder according to an embodiment of the present invention, in which reference numeral 11 is a matrix circuit, reference numeral 12 is a modulation circuit, reference numeral 14 is a color carrier wave oscillator, reference numeral 15 is a 90' phase shifter, and 16 is a block diagram showing a color encoder according to an embodiment of the present invention.
．． 18 is an adder, 17 is a bandpass filter, K1 and 2 are weighting circuits, and the above configuration is the same as the configuration shown in FIG.

19 is a delay circuit, such as a delay line or CCD (Charg
output terminal TO of the luminance signal (Y signal) of the matrix circuit 11.
It is provided between I and the input terminal T11 of the adder 18, and is used to delay the luminance signal by a desired time and input it to the adder 18.

In the case of the present invention, the desired time for delaying the luminance signal is:
Below the output terminal of the chroma signal (C signal) of the matrix circuit 11. 2. The output from TO3 is delayed by passing through signal processing circuits such as modulation circuits 12 and 13, and then sent to adder 18.
The delay time is set to be the same as the delay time of the chroma signal input to the input terminal TI2 of the chroma signal. Further, a burst signal and the like are input to TI3.

FIG. 2 shows another embodiment of the present invention, in which a color encoder is actually applied to an ultrasonic diagnostic apparatus. VBS output from color encoder 10
The signal is input to the VTR 20. The output of the VTR 20 is outputted via the color decoder 30, and each output signal [)e
cR, DecG.

DeCB is added to the display. The output of the VTR 20 is input to a color encoder 30 and then separated into a luminance signal and a chroma signal. Further, the R-Y and G-Y signals of the chroma signal are passed through a bandpass filter 31 to demodulation circuits 32 and 33, respectively.
Added to [)em (RY), Dem (B-Y)
Output as a signal. These output signals Dem (R-
Y) and Dem(B-Y) signals are each passed through a low-pass filter 3.
4.35, for example 6MHz (1 in the actual NTSC system)
゜5 MHz), LPF (R-Y)
.

It is output as an LPF (B-Y) signal and input to the matrix circuit 36. The matrix circuit 36 is an inverse matrix to the matrix circuit 11 of the color encoder 10,
By performing the opposite operation, DecR, DecG
, DecB signal is output. These output signals are applied to a display.

37 is a sync separation circuit, and 38 is a notch filter for luminance signals.

Next, the operation of this embodiment will be explained.

The signals shown in FIGS. 3A and 3B are input to the R and G terminals of the matrix circuit 11 of the color encoder 10, respectively.

That is, input the R signal (1 Pi Similarly, input the C signal to the terminal.Adding the R and C signals in the same phase is to obtain a yellow color, and inputting the C signal alone is to obtain a green color.Such a yellow color .

The color green was chosen to be displayed as a dot on the monitor (display) of the ultrasound diagnostic device. Each of these input signals passes through the matrix circuit 11, and then the luminance signal in FIG. 4(a) and the R as in FIG. 4(b) and (c)
-Y and B-Y color difference signals are output as chroma signals. Among these, the chroma signals are modulated by the respective modulation circuits 12 and 13.
After being modulated by , the signal is output as shown in FIGS. 6(a) and 6(b). FIGS. 5(a) and 5(b) show waveforms of color carrier waves, which are modulation signals, each having a 90° phase shift. It is assumed that the R-Y and B-Y color difference signals are clamped at the beginning of horizontal synchronization, and that their respective offset voltages do not vary when input to the modulation circuit. The output signal of each modulation circuit is weighted according to the NTSC system and then inputted to an adder 16, and after passing through a bandpass filter, is outputted as a ROMA signal as shown in FIG.

On the other hand, the luminance signal is input to the adder 18 after passing through the delay circuit 19, and is added to the chroma signal shown in FIG. As a result, the adder 18, that is, the color encoder 10 outputs a VBS signal as shown in FIG.

This VBS signal is input to the VTR 20, and output from the VTR 20 to the color decoder 30 during playback. It is assumed that the VTR 20 has a straightforward frequency characteristic. The VBS signal input to the color decoder 30 is separated into a luminance signal and a chroma signal, but the chroma signals R-Y and G-B signals that have passed through the bandpass filter 31 are processed by demodulation circuits 32 and 33 as shown in FIG. The output is as shown in a) and (b). These output signals are passed through a low-pass filter 34°3
5, the signal is output as shown in FIGS. 10(b) and 10(c) and input to the matrix circuit 36.

It is assumed that the luminance signal notch filter 38 has ideal characteristics and can obtain a luminance signal equivalent to that in the color encoder 10.

The luminance signal shown in FIG. 10 (a) and RY shown in FIGS. 10 (b) and (c) applied to the matrix circuit 36.

The G-Y signal is output as shown in FIG. 11 (a>, (b), and (c)).

FIG. 11(a) shows the output from the matrix circuit 36, that is, the color decoder 30 in this manner.

In the DecR, DecG, and DecB signals of (b) and (c), almost all color information is lost compared to the RGB signal input to the color encoder 10, and only luminance is reproduced.

However, by calculating the average Y of those three signals as Y = (DecR+DecG+DecB)/3, the remaining small amount of color information can be reduced to Dec.
It can be indicated as R-'i', DecG-Y, DecB-Y.

Figures 2 (a) to (d> show each signal obtained in this way compared with the Y signal, and Figure 12 (a> is Y).
The signal, Fig. 12 (b) is the DeCR-Y signal, Fig. 12 (
c) is the DeCG-Y signal.

FIG. 12 (d> shows the [)ecB-Y signal.

As is clear from the comparison with the conventional results shown in FIGS. 15(a> to (d)), although the levels of each color signal in FIGS. (
The time phase of the peak portion of each color signal from b) to (d>) is (a)
can match the time phase of Y (luminance signal). This is the same as when the luminance signal output from the matrix circuit 11 of the color encoder 10 is input to the adder 18 via the delay circuit 19, and the chroma signal is delayed via a signal processing circuit such as a modulation circuit. This can be obtained by making the time pass.

By eliminating the time phase difference between the luminance signal and chroma signal in this way, even if the output signal obtained from the color decoder contains only a small amount of color information (even if the saturation is low),
Hue can be reproduced using this small amount of color information. For example, in the time phase 11 portion of FIG. 12(a), a yellow color corresponding to the time phase t1' portion of FIG. 3(a) is obtained, and in the time phase 12 portion, a green color can be obtained in the same manner. Therefore, in ultrasound diagnostic equipment, these yellow,
The green color can be displayed as a dot on the monitor.

Although the present embodiment has been described using the NTSC system as an example, the present invention is not limited to this, and the same effect can be obtained by applying it to other color-only systems such as the PAL system.

[Effects of the Invention] As described above, according to the present invention, since the luminance signal output from the matrix circuit is added to the adder via the delay circuit, the time phase difference that exists between it and the chroma signal can be reduced. It can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a color encoder according to an embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention,
Figure 3 (a), (b), Figure 4 (a) to (C), Figure 5
Figures (a), (b), Figures 6 (a), (b), Figures 7, 8, and 9 (a). (b), FIG. 10 (a> to (C)), FIG. 11 (a> to (C)), and FIG. 12 (a) to (d) are signal waveform diagrams for detailed explanation of the present invention, Figure 13 is a block diagram showing a conventional example, Figures 14 (a) to (C) and Figure 15 (a).
> to (d> are signal waveform diagrams showing drawbacks of the conventional example, No. 16
The figure shows a monitor image of a conventional example. 10... Color encoder, 11... Matrix circuit, 12.13... Modulation circuit. 14...Emitter, 15...90° phase shifter, 16.1
8... Adder, 17... Bandpass filter, 19...
delay circuit. (G) (a) (b)
(b) D@CR (b) Figure 15 Figure 12 Procedure for writing amendments) 7 March 24, 1988 Patent Application No. 229175 of 1988 2, Title of Invention Color Encoder 3, Person Who Makes Amendment Case Relationship with Patent applicant 4, agent 5, date of amendment order (shipment date) February 23, 1988 6, subject of amendment (1) column for brief explanation of drawings in specification, content of amendment ( 1) "Fig. 14 (a) to (C>and") written in page 14, line 10 to line 11 of the specification is corrected to "Fig. 14 (a) and (b) and".

Claims (2)

[Claims] (1) In a color encoder that outputs a luminance signal and a chroma signal from a matrix circuit and adds the luminance signal and chroma signal via a signal processing circuit to an adder, the luminance signal is added to the adder via a delay circuit. Features a color encoder. (2) The color encoder according to claim 1, wherein the signal processing circuit is a modulation circuit.