JP3052582B2 - Luminance signal / color signal separation circuit and television receiver or video signal recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NTSC color television receiver and a video signal recording / reproducing apparatus, and more particularly to an improved luminance signal / chrominance signal separation circuit (hereinafter referred to as luminance signal / color signal). Separation circuit).

[0002]

2. Description of the Related Art In recent years, color television receivers have been required to have higher image quality as the screen size increases. In particular, there is a demand for improvement in the performance of a luminance signal / color signal separation circuit that greatly affects image quality.

Hereinafter, a conventional luminance signal / color signal separation circuit will be described. FIG. 3 is a block diagram of a conventional luminance signal / color signal separation circuit. In FIG.
Reference numeral 1 denotes a one-line delay circuit that delays a video signal by one horizontal scanning period. Reference numeral 2 denotes a first subtractor for subtracting the output of the one-line delay circuit from the video signal. Reference numeral 3 denotes an attenuator for halving the output amplitude of the subtractor. Reference numeral 4 denotes a band-limiting filter that passes only the vicinity of the color subcarrier frequency out of the output of the attenuator 3 to generate a color signal. Reference numeral 5 denotes a second subtractor for subtracting the output of the band-limiting filter from the video signal to generate a luminance signal.

The operation of the conventional luminance signal / chrominance signal separation circuit configured as described above will be described below. First, the input video signal is delayed by one horizontal scanning period by the line delay circuit 1. Here, in the NTSC system, since the phase of the color subcarrier is shifted by 180 degrees every one horizontal scanning period, the luminance is obtained by taking the difference between the video signal and the video signal delayed by one horizontal scanning period by the first subtractor 2. The signal is canceled and only the color signal component remains. Then, the color signal is finally obtained by extracting only the necessary color sub-carrier frequency vicinity from the necessary colors by the attenuation calculator 3. Further, a luminance signal is obtained by subtracting the color signal from the video signal by the band limiting filter 4.

[0005]

However, in the above configuration, when a video signal having a change in a luminance signal or a chrominance signal in the vertical direction as shown in FIG. At the boundary between the luminance signal or the chrominance signal in the vertical direction, cross luminance, which is leakage of the color signal component into the luminance signal, and cross color, which is leakage of the luminance signal component into the chrominance signal, occur. There was a problem that.

The present invention solves the above-mentioned conventional problems, and obtains a stable image with less cross luminance and cross color even for a video signal in which a luminance signal or a chrominance signal changes in the vertical direction. It is an object of the present invention to provide a luminance signal / chrominance signal separation circuit capable of performing the above operation.

[0007]

In order to achieve this object, a luminance signal / chrominance signal separation circuit according to the present invention comprises a band-limiting filter for passing only a portion of a video signal near a color subcarrier frequency, and an output of the band-limiting filter. A one-line delay circuit that delays by one horizontal scanning period, an adder that takes the sum of the output of the one-line delay circuit and the output of the band-limiting filter, an inverter that inverts the output of the adder, In the output, the output of the one-line delay circuit, and the output of the band limiting filter, the corresponding portions of each signal are arranged in order of magnitude.
Te and intermediate value selecting circuit for selecting the intermediate signal, a first subtractor creating the color signal from the output of said band-limiting filter by subtracting the output of the intermediate value selection circuit, from the video signal of the first subtracter It has a configuration that includes a second subtractor that subtracts an output to generate a luminance signal.

[0008]

With this configuration, first, only the vicinity of the color subcarrier frequency in the video signal is extracted by the band limiting filter. Then, the signal and the one-line delay circuit
The intermediate value selection circuit detects a change in the color signal in the vertical direction with respect to the signal delayed in the horizontal scanning period and the signal obtained by adding the two in the adder, and when there is no change in the luminance signal or the color signal, The output of the adder is output as is, the first subtractor subtracts the signal from the signal before being delayed by one horizontal scanning period to obtain a color signal, and the second subtractor subtracts the color signal from the video signal to obtain a luminance signal. And the same luminance signal and color signal as those of the conventional luminance signal / chrominance signal separation circuit are output. However, if there is a change in the luminance signal in the vertical direction, the output of the first subtractor is canceled out to zero and the color signal becomes zero because the intermediate value selection circuit outputs the signal before being delayed by one horizontal scanning period at the boundary. The cross color appearing in the output can be eliminated, and the cross luminance appearing in the luminance signal output can be eliminated. If there is a change in the color signal in the vertical direction, the intermediate value selection circuit outputs a signal delayed by one horizontal scanning period at the boundary, so that the output becomes zero because the output of the first subtractor is one horizontal scanning period. It is possible to eliminate the cross color appearing in the color signal output by outputting the signal before being delayed as it is, and also eliminate the cross luminance appearing in the luminance signal output.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 6 denotes a band-limiting filter that passes only the vicinity of the color subcarrier frequency of a video signal, 7 denotes a one-line delay circuit that delays the output of the band-limiting filter 6 by one horizontal scanning period, and 8 denotes the 1-line delay circuit. An adder that takes the sum of the output of the line delay circuit 7 and the output of the band limiting filter 6;
Reference numeral 9 denotes an inverter for inverting the output of the adder 8, and reference numeral 10 denotes an intermediate for selecting a signal having an intermediate value among the output of the inverter 9, the output of the one-line delay circuit 7, and the output of the band limiting filter 6. The value selection circuit 11 is provided with the band limiting filter 6.
Is a first subtractor that subtracts the output of the intermediate value selection circuit 10 from the output of the first selector to generate a color signal, and 12 is a second subtractor that subtracts the output of the first attenuator 11 from the video signal to generate a luminance signal.

[0011] In the luminance signal / color signal separation circuit configured as described above will be described with reference to FIG.
First, only the vicinity of the color subcarrier frequency in the video signal a is extracted by the band limiting filter 6 (b in FIG. 1) . Then, the signal b and the signal c obtained by delaying the signal b by one horizontal scanning period by the one-line delay circuit 7 and the signal d obtained by summing the two by the adder 8 are converted into a vertical color signal by the intermediate value selection circuit 10. Detect changes in And the first subtractor 11
The signal e output from the intermediate value selection circuit 10 is
Extract only the vicinity of the color subcarrier frequency in the video signal a
The difference signal f (f = be) from the obtained signal b is used as a color signal.
Output, and in the second subtractor 12,
A signal obtained by subtracting the difference signal f from the video signal a (a-
f) as a luminance signal,
-And cross luminance are eliminated.
You. Next, using the waveform diagram of FIG.
Luminance and chrominance signals that do not cause sulminance can be obtained.
Explain that Although not shown in FIG.
If there is no change in the luminance signal or color signal,
From signal a near the color subcarrier frequency by band limiting filter
Is extracted from the signal b after 1H delay of the extracted signal b.
Is the signal that causes cross color and cross luminance.
No color component exists, so the separated color signal and luminance signal
No cross color and no cross luminescence occur. Figure
2 shows a waveform when the luminance signal changes in the vertical direction.
The waveform a is a luminance signal in the input video signal a.
And the waveform of the color signal, and the waveform b is the input video signal a
Shows the waveform after passing through the band-pass filter 6;
c is only around the color subcarrier frequency by the band limiting filter
Of the signal c after delaying the extracted signal b by 1H
And a waveform d is a signal obtained by adding the signal b and the signal c.
Is a signal d inverted from the above. Further, the waveform e is
An intermediate value between these signals b, c and d is an intermediate value.
Shows the waveform of the signal e selected by the selection circuit 10
The intermediate value selection circuit 10 determines that each signal is, for example, large
If b <c <d, the value of c is selected, and d <
If b = c, the value of b is selected, and b = c = d (=
In the case of 0), an operation is performed to select c = 0. Follow
Thus, the waveforms of the signals b, c and d are as shown in FIG.
In this case, the signal selected by the intermediate value selection circuit 10
The waveform of signal e is divided as shown in FIG.
Then, in the first half of the first section, the signal b, the signal c, and the signal
The magnitude of the amplitude of d is d <b = c, and in the latter half, b
= C <d, the intermediate value selection circuit in the first section
The output from 10 is b, and the waveform of signal e is the waveform of signal b.
It becomes the same as the shape. Similarly, in the section 2, the signal e = signal
No. b. In the first half of Category 3, d <b <c, in the second half
Satisfies c <b <d, so the intermediate value selection in section 3
The output from the circuit 10 is b, and the signal b of the section 3 is 0.
Therefore, the signal e = 0. Also, in Category 4
Since b = c = d = 0, the signal e = 0. Ward
In the first half of minute 5, d <c <b, and in the second half, b
<C <d, the waveform of the signal e of the section 5 becomes c.
Since c = 0, the signal e = 0 also in the section 5
Becomes Further, in the first half of the section 6, b <d <c
In the latter half, since c <d <b, the signal e of section 6
Is d, and d = 0, so in Section 6,
Also, the signal e = 0. When this is arranged, the division (1,
2, 3, 4, 5, 6) corresponding to the intermediate value selection circuit 10
Is (b, b, 0,0,0,0).
A waveform e of FIG. Therefore, the signal e is the luminance signal
Other divisions except for the same waveform as waveform b in divisions 1 and 2
Are all 0, and the signal b and the signal
Taking the difference (be) from the signal e, the waveform of the difference signal f
By taking the difference between waveforms b and e as shown in FIG.
Waveform f. In the second subtractor 12,
The waveform of the difference (af) between the input video signal a and the signal f is shown in FIG.
By taking the difference between the waveform a and the waveform f as shown in FIG.
It becomes like a luminance signal output waveform (af). Luminance signal
Y, color signal C and cross color, cross luminance
The signal waveform of FIG.
In minutes 1 to 6, the state of each signal is summarized as follows.
Swell. Waveform a ⇒ (Y, Y, 0, 0, Cr, -Cr) Waveform b ⇒ (h, h, 0, 0, Cr, -Cr) Waveform c ⇒ (h, h, h, 0, 0, Cr) Waveform [b + c] ⇒ (2h, 2h, h, 0, Cr, 0) Waveform d ⇒ (-2h, -2h, -h, 0, -Cr, 0) Waveform e ⇒ (h, h, 0, 0, 0, 0) Waveform f: be ⇒ (0, 0, 0, 0, Cr, Cr) → color signal Waveform [af] ⇒ (Y, Y, 0, 0, 0, 0) → luminance signal As described above, the signal e has a cross color during the luminance signal period,
Has only the signal component h that causes cross luminance
Since the signal becomes a waveform signal, the first subtractor 11
From the signal b that has passed through the band limiting filter 11
By subtracting the signal e, the color signal and the signal component h are included.
Remove only the signal component h from the signal b
Color signals can be separated. Further, the signal f is
Since it is only a complete color signal, the second subtractor
By subtracting the signal f from the input video signal a,
It can separate luminance signals without cross luminance.
You.

As described above, according to this embodiment, the band limiting filter 6 that passes only the vicinity of the color subcarrier frequency of the video signal, and the one-line delay circuit that delays the output of the band limiting filter 6 by one horizontal scanning period 7, an adder 8 for taking the sum of the output of the one-line delay circuit 7 and the output of the band limiting filter 6, an inverter 9 for inverting the output of the adder 8, and an output of the inverter 9. An intermediate value selecting circuit 10 for selecting a signal having an intermediate value between the output of the one-line delay circuit 7 and the output of the band limiting filter 6, and subtracting the output of the intermediate value selecting circuit 10 from the output of the band limiting filter 6. By providing a first subtractor 11 for producing a color signal and a second subtractor 12 for producing the luminance signal by subtracting the output of the first attenuator 11 from the video signal, Cross-luminance and Kurosukara occurring at the boundary in the screen with reduction - can be eliminated.

[0013]

As described above, the present invention provides a band limiting filter for passing only the vicinity of the color subcarrier frequency of a video signal, a one-line delay circuit for delaying the output of the band limiting filter for one horizontal scanning period, An adder for taking the sum of the output of the one-line delay circuit and the output of the band-limiting filter;
An inverter for inverting an output of the adder, an intermediate value selecting circuit for selecting a signal having an intermediate value among an output of the inverter, an output of the one-line delay circuit, and an output of the band limiting filter; By providing a first subtractor that subtracts the output of the intermediate value selection circuit from the output of the limiting filter to produce a color signal, and a second subtractor that subtracts the output of the attenuator from the video signal to produce a luminance signal, It is possible to realize an excellent luminance signal / color signal separation circuit capable of eliminating cross luminance and cross color occurring at the boundary of a screen having a change in luminance signal or color signal in the direction.

[Brief description of the drawings]

FIG. 1 is a block diagram of a luminance signal / color signal separation circuit according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation of the luminance signal color / signal separation circuit in the embodiment.

FIG. 3 is a block diagram of a conventional luminance signal / color signal separation circuit.

FIG. 4 is a signal waveform diagram for explaining the operation of a conventional luminance signal / color signal separation circuit.

[Explanation of symbols]

 7 1-line delay circuit 6 Band limit filter 8 Adder 9 Inverter 10 Intermediate value selection circuit 11, 12 Subtractor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-222593 (JP, A) JP-A-1-319387 (JP, A) JP-A-2-94988 (JP, A) JP-A-4-199 46486 (JP, A) JP-A-6-6824 (JP, A) JP-A-63-232782 (JP, A) JP-A-63-304789 (JP, A) JP-A-1-108890 (JP, A) JP-A-1-206794 (JP, A) JP-A-1-208988 (JP, A) JP-A-62-188584 (JP, A) JP-A-2-125596 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 9/44-9/898

Claims (2)

(57) [Claims] 1. A band-limiting filter that passes only near a color subcarrier frequency of a video signal, a one-line delay circuit that delays an output of the band-limiting filter by one horizontal scanning period, and an output of the one-line delay circuit. the size of the adder summing the output of the band-limiting filter, and inverter for inverting the output of said adder, the output of the output and the band limiting filter and output the 1-line delay circuit of the inverter
An intermediate value selection circuit by arranging in order to select the intermediate signal, a first subtracter for making a color signal by subtracting the output of the intermediate value selection circuit from an output of the band-limiting filter, the movies <br/> image and a second subtracter for making the luminance signal from the signal by subtracting the output of said first subtracter, eliminating cross-luminance and cross-color generated in the boundary on the screen in the vertical direction there is a change in the luminance signal or color signal A luminance signal / color signal separation circuit characterized in that: 2. A color television receiver or a video signal recording / reproducing device comprising the luminance signal / color signal separation circuit according to claim 1.