JPH0632452B2 - Y / C separation circuit of video processing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used in a color television receiver or the like, and is used in a video processing unit that performs input processing of a video signal or the like. Y to separate the color carrier (C) signal
/ C separation circuit.

[Conventional example] Conventionally, since a color carrier signal to be input is phase-inverted for each scanning line in a video processing unit such as a color television receiver, for example, Y / Y as shown in FIG. A C separation circuit (comb filter) is provided.

In the figure, one scanning line portion of a luminance signal and a color carrier signal, for example, a video signal is delayed by one scanning line delay circuit 1,
The delayed one scanning line and the one scanning line actually input to the one scanning line delay circuit 1 are added by the adder 2 and subtracted by the subtractor 3. The signal obtained by the adder 2 is the luminance signal, and the signal obtained by the subtractor 3 is the chrominance carrier signal.

[Problems to be Solved by the Invention] In the Y / C separation circuit, since the display of the television receiver is based on the interlace system, one scanning line O _l , O _{l + 1} ( Odd number), or 1
The scanning lines E _l and E _{l + 1} (even numbers) are added together by the adder 2,
Subtraction processing is performed by the subtractor 3. That is, since the addition and subtraction are performed for one scan line and one scan line,
The color carrier signal is easily mixed with the luminance signal, and the luminance signal is easily mixed with the color carrier signal, which causes the vertical resolution of the display screen to be deteriorated and causes a cross color failure.

Therefore, next to the one scan line O _l, adding the E _l each other, it is conceivable to subtraction, this case, the total number scan lines of the display screen n
In this case, at least about n / 2 one scanning line delay circuits are required, which not only increases the size of the circuit board but also increases the cost.

The present invention has been made in view of the above problems, and an object thereof is to perform separation of a luminance signal and a chrominance carrier signal very well, to raise the vertical resolution of a display screen of a television receiver, and to prevent a cross color interference. Another object of the present invention is to provide a Y / C separation circuit capable of preventing the above.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is a video processing unit for input-processing a video signal input to a color television receiver or the like, and a luminance (Y) higher than that of the video signal. In a Y / C separation circuit for separating a signal and a color carrier (C) signal, a first one scanning line delay circuit for delaying the luminance signal by one scanning line and a first one scanning line delay circuit for delaying the color carrier signal by one scanning line 2 1 scanning line delay circuit, 1 scanning line segment delayed by the first 1 scanning line delay circuit, and 1 scanning line segment actually input to the 1st 1 scanning line delay circuit are subtracted. A first subtraction circuit,
A first adder circuit for adding one scanning line segment delayed by the second one scanning line delay circuit and one scanning line segment actually input to the second one scanning line delay circuit; The luminance signal output from the subtraction circuit of 1 is delayed by 2 scanning lines, and
A luminance signal output circuit for adding and outputting the luminance signal delayed by the scanning line and the luminance signal actually output by the first subtraction circuit, and a color carrier signal output from the first addition circuit. A color signal output circuit that delays by two scanning lines and that subtracts the color carrier signal delayed by two scanning lines and the color carrier signal actually output by the first adding circuit and outputs the subtracted color signal output circuit Is.

[Operation] In the above configuration, the input carrier signal by the comb filter,
For example, when the luminance signal and the color carrier signal are separated from the video signal, this luminance signal is obtained by adding one scanning line segment delayed by one scanning line segment, and conversely, the color carrier signal divides them. It is obtained by subtraction. The luminance signal is subtracted by the first scanning line delay circuit and the first subtraction circuit from the delayed one scanning line segment and the currently input one scanning line segment. The subtracted luminance signal is delayed by two scanning lines by the fourth and fifth scanning line delay circuits, and is actually input as the delayed one scanning line by the third adding circuit. It is added to one scanning line. As a result, the added luminance signal has the influence from the adjacent scanning line removed. The chrominance carrier signal is processed in exactly the same manner as the luminance signal.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. In the figure, the same parts as those in FIG.

In FIG. 1, a luminance (Y) signal is obtained by an adding circuit 2 and a chrominance carrier (C) signal is obtained by a subtracting circuit 3 from an input video signal or the like. The luminance signal and the chrominance carrier signal are delayed by one scanning line by the first scanning line delay circuit 4 and the second scanning line delay circuit 5, respectively. The luminance signal delayed by the first one scanning line delay circuit 4 and the luminance signal (next one scanning line) actually input to the first one scanning line delay circuit 4 are sent to the first subtraction circuit 6. And the color carrier signal delayed by the second 1-scan line delay circuit 5 and the color carrier signal actually input to the second 1-scan line delay circuit 5 (next 1
The scanning line segment) is added by the first addition circuit 7. The luminance signal output from the second subtraction circuit 6 is delayed by two scanning lines in the luminance signal output circuit 8, and the delayed luminance signal and the luminance signal actually output from the first subtraction circuit 6 And are added, and the luminance signal Y ₀ is obtained by this addition. Therefore, the luminance signal output circuit 8 includes the fourth and fifth one scanning line delay circuits 8 for delaying two scanning lines of the luminance signal.
a and 8b, and a second adder circuit 8c for adding the brightness signal delayed by the two scanning lines and the brightness signal actually output from the first subtraction circuit 6. On the other hand, the chrominance carrier signal output from the first adding circuit 7 is delayed by two scanning lines in the chrominance signal output circuit 9, and the delayed luminance signal is actually output from the first adding circuit 7. Luminance signal is subtracted, and the color carrier signal C ₀ is obtained by this subtraction. Therefore, the color signal output circuit 9 includes sixth and seventh scanning line delay circuits 9a and 9b for delaying two scanning line components of the color carrier signal, and a color carrier signal and a second scanning line delay circuit for delaying the two scanning line components. A second subtraction circuit 9c for subtracting the color carrier signal actually output from the first addition circuit 7 is provided.

Next, the operation of the Y / C separation circuit having the above configuration will be described based on the chart of FIG. In addition, L ₁ , L ₂ , ... Corresponds to one scanning line segment (raster) in the horizontal direction of the display screen.

First, from the addition circuit 2 and the subtraction circuit 3, it is assumed that the luminance signal and the color carrier signal are separated from the input video signal as in the conventional case.

That is, as shown in FIGS. 4A to 4D, when a video signal (Y + C) including a luminance signal and a color carrier signal is input in the order of rasters L ₁ , L ₂ , ... The scanning line delay circuit 1 delays one scanning line, and the delayed video signal and the video signal actually input to the one scanning line delay circuit 1 are added by the addition circuit 2 and the subtraction circuit 3 is added. Is subtracted. As a result, the addition circuit 2 outputs a luminance signal separated from the video signal, and the subtraction circuit 3 outputs a color carrier signal.

The luminance signal is delayed by one scanning line in the first one scanning line delay circuit 4 (see FIG. 6E), and the delayed luminance signal and the first one scanning line delay circuit 4 actually The input luminance signal is subtracted by the first subtraction circuit 6 (see (f) in the figure). As a result, the from the first subtraction circuit 6, a raster L ₁ of the input video _{signal, L 2, L 3, L} 4, ... to, addition, although delayed subtraction processing time, raster L ₁ at substantially the same timing , L ₂ , L _{3
-L 1, L 4 -L 2,} ... ( luminance signal) is outputted.

The luminance signal obtained by the first subtraction circuit 6 is delayed by two scanning lines by the third and fourth one scanning line delay circuits 8a and 8b (see (h) in the figure), and then delayed. And the luminance signal actually output from the first subtraction circuit 6 is the second luminance signal.
Are added by the adder circuit 8c (see (g) in the same figure). As a result, raster L ₁ of the input _{signal, L 2, L 3, L} 4, ... to, substantially raster L ₁ at the same _{time, L 2, L 3, L} 4, ... ( luminance signal) is outputted.

That is, the conventional luminance signal is a signal obtained by combining two scanning lines (see (c) in the same figure), but the luminance signal Y ₀ according to the present invention is a signal of only one scanning line ( Same figure
(See (f)).

On the other hand, also in the chrominance carrier signal, as in the case of the luminance signal, the chrominance carrier signal C ₀ by the signal of only one scanning line is obtained. The detailed description is omitted because it is the same as the case of the luminance signal.

As described above, since the obtained luminance signal and chrominance carrier signal are not a combination (addition, subtraction) of adjacent one scanning lines, it is possible to remove the influence from the adjacent scanning lines, and to reduce the vertical direction of the display screen. The resolution can be improved and the cross color interference can be reduced. In particular, in the case of a communication system using interlace, one scanning line or one scanning line, for example, O _l , O _{l + 1} (see FIG. 4) is combined (added, subtracted), and thus more effective. Is.

[Effects of the Invention] As described above, according to the Y / C separation circuit of the present invention, it is possible to remove the influence of the adjacent scanning line from the luminance signal and the chrominance carrier signal separated from the input signal, It is possible to improve the vertical resolution of the display screen of a color television receiver or the like and prevent a cross color failure.
Moreover, according to the present invention, a slight one-scan line delay circuit,
Since it can be configured with an addition circuit and a subtraction circuit,
It can be done at low cost.

[Brief description of drawings]

FIG. 1 shows a Y / C of a video processing unit showing an embodiment of the present invention.
FIG. 2 is a schematic block diagram of a separation circuit, FIG. 2 is a chart diagram for explaining the operation of the Y / C separation circuit, FIG. 3 is a schematic block diagram of a conventional Y / C separation circuit, and FIG. Y
FIG. 11 is a display screen diagram for explaining a raster scan system of a television receiver in which the / C separation circuit is used. In the figure, 1 is a 1-scan line delay circuit, 2 is an adder circuit, 3 is a subtractor circuit, 4 is a first 1-scan line delay circuit, 5 is a second 1-scan line delay circuit, and 6 is a first subtractor circuit. , 7 is a first adder circuit, 8 is a luminance signal output circuit, 8a is a third scan line delay circuit, 8b is a fourth scan line delay circuit, 8c is a second adder circuit, and 9 is a color signal. An output circuit, a fifth scanning line delay circuit 9a, a sixth scanning line delay circuit 9b, and a second subtraction circuit 9c.

Claims (1)

[Claims] 1. A Y-shaped filter for separating a luminance (Y) signal and a color carrier (C) signal from the video signal by a comb filter of a video processing unit which inputs and processes a video signal input to a color television receiver or the like. In the / C separation circuit, a first 1-scan line delay circuit 4 that delays the luminance signal by 1 scan line, a second 1-scan line delay circuit 5 that delays the chrominance carrier signal by 1 scan line, and A first subtraction circuit 6 for subtracting one scanning line segment delayed by the first one scanning line delay circuit 4 and one scanning line segment actually input to the first one scanning line delay circuit 4; A first adder circuit 7 for adding one scanning line segment delayed by the second one scanning line delay circuit 5 and one scanning line segment actually input to the second one scanning line delay circuit 5; A third and a fourth scanning for delaying the luminance signal output from the first subtraction circuit 6 by two scanning lines Delay circuit 8a, 8b
And a luminance signal output circuit 8 having a second adding circuit 8c for adding the luminance signal delayed by two scanning lines by the delay circuits 8a and 8b and the luminance signal actually output from the first subtracting circuit 6. The color carrier signal output from the first adding circuit 7
Fifth and sixth one-scan line delay circuits 9a for delaying the number of scan lines,
9b and a color carrier having a second subtracting circuit 9c for subtracting the color carrier signal delayed by two scanning lines by the delay circuits 9a and 9b from the color carrier signal actually output from the first adding circuit 7. And a signal output circuit 9, wherein the luminance signal and the color carrier signal output from the luminance signal output circuit 8 and the color carrier signal output circuit 9 are output signals of the Y / C separation circuit. Y / C separation circuit of processing unit.