JP2001095011A - Yc separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize YC separating operation with higher accuracy for an extremely non-standard composite video signal down-converted from a MUSE signal to an NTSC signal. SOLUTION: This YC separator supplies a 2xn line delay signal with optimal line correlation to a comb filter when a down-converted signal is inputted by using an MN discriminating device 209, to discriminate whether an inputted signal is a MUSE-NTSC down-convert signal, line memories 202, 203 capable of switching the number of stages to 910 and 909, and a changeover SW 208 to switch a signal to be inputted in the comb filter to a signal delayed by n lines or a signal delayed by 2 xn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver, and more particularly to a YC separation device for accurately YC separating a composite video signal (hereinafter referred to as an MN composite signal) down-converted from the MUSE system to the NTSC system. It is.

[0002]

2. Description of the Related Art In recent years, a television receiver has been required to support various input sources. Among them, it is important how much each device in the image receiver can operate without errors with respect to non-standard signals such as VTRs, game machines, and MN composite signals. The YC separation device is also one of the devices that easily malfunctions. As a basic element of the YC separation apparatus, a comb filter using line correlation can be cited, and the principle thereof will be briefly described with reference to FIG. In the case of a standard NTSC signal, the phase of the color signal on the nth line and the phase of the color signal on the (n + 1) th line are inverted. On the other hand, the phase of the luminance signal is equal in any line. By using this characteristic and subtracting the (n + 1) th line from the (n + 1) th line (inverting and adding the (n + 1) th line), for example, assuming that the same picture pattern continues in the vertical direction, the color signals have the same phase and the gain is twice Is output as
Since the phase of the luminance signal is inverted, if added, the signal becomes a zero signal. As a result, only the color signal is output. Further, a luminance signal can be obtained by subtracting the color signal obtained from the original signal. In addition, the characteristic of inverting between color signal lines as described above is that the frequency of one horizontal cycle (hereinafter referred to as 1H) is f _H ,
Assuming that the frequency of the color subcarrier is f _SC , f _SC = 227.5
It is given by f _H. Conversely, it can be said that the establishment of this relationship is the premise of the comb filter operation. However, in the case of a non-standard signal, this relationship does not always hold, and a slight shift occurs. The operation at this time will be described with reference to FIG. The left sine wave of the n-th line is a color signal, and the right impulse wave is a luminance signal. Now
As a standard configuration, a one-line delay is applied to a line memory 91 by a quadrupled clock of a burst locked to a burst.
When it is assumed that the color signal is obtained by the 0 clock delay, the phase of the (n + 1) th line of the color signal is properly inverted,
For the luminance signal, 4f _SC = 227.5 × 4 (= 91
0) Since f _H does not occur, a signal obtained as a dotted line in the standard time shifts as a solid line in the non-standard time. Due to this shift, a false color signal (cross color) is generated in the area A of the color signal which should be a zero signal as shown in the figure. In addition, 91 of H which locked the clock of the line memory to H
If the clock is multiplied by 0, the phase of the luminance signal will be reversed, and the phase of the chrominance signal will not be coincident. As an apparatus for performing good YC separation using such a signal, for example, Japanese Patent Publication No. 9-2686115 (H0
4N 9/78).

[0003] An example of the above-described conventional YC separation apparatus will be briefly described below with reference to FIG. FIG.
1 is a block diagram of a YC separation device proposed in Japanese Patent Publication No. 9-2686115. FIG.
In the block diagram of FIG. 7, reference numeral 701 denotes a burst lock PLL device that generates a burst lock clock locked to a color burst of an input composite video signal. 7
An H-lock PLL device 02 generates an H-lock clock locked to the horizontal synchronizing signal of the input composite video signal. 703 is an A / D converter device. A phase detection device 704 detects the phase of the input sampling point. Reference numeral 705 denotes a frequency ratio detection device that detects a frequency ratio between the standard 4f _SC and the current 4f _SC . 70
Reference numeral 6 denotes a correction coefficient calculation device that outputs a correction coefficient for correcting a phase shift of a color signal when a non-standard signal is sampled by the H lock clock as described above according to a frequency ratio. 707 is a composite video signal input terminal. 708 is a comb filter, which operates on the H lock clock,
A provisional color signal is output by the line correlation operation. 709
Is a multiplier whose output is a color signal (C).

[0004] The operation of the above-configured YC separation apparatus will be described below. First, sampling is performed at 703 using the burst lock clock 70A as the H lock clock 70B and the sampling clock. Based on the sampling data, the phase between the burst and H is detected at 704. The detection method can be realized by a table lookup method using a ROM or the like. From the phase detection output, the frequency ratio is detected by 705. The correction coefficient of the C signal is obtained from the frequency ratio by 706, and 7
0F is output. This can be realized by a table lookup method using a ROM or the like. Further, the input composite video signal 70G becomes a provisional C signal 70H by a comb filter 708 operated by an H lock clock, and a C output 70I multiplied by the correction coefficient 70F is obtained.

[0005]

However, with the above configuration, the system becomes very complicated and the A /
It is very expensive due to the need for D, ROM and the like.
Also, even non-standard signals, there are almost no visually problematic signals unless a three-dimensional comb operation using frame correlation is performed. However, for the MN composite signal, f _H = 15.75 kHz, f _SC = 3.579545
MHz, f _SC = 227.2727f _H , 4f _SC = 90
9.09f _H ≒ 909f _H (f _SC = 227.
5f _H, that 4f _{S C} = 910f _H), holds the significant deviation relationship from the standard state to the static, also has almost without degrading the high-frequency component of the luminance signal, two-dimensional using a line correlation Even in the case of a comb, the cross color and dot disturbance as described above are liable to occur, and some measures are required.

[0006]

In order to solve the above-mentioned problems, a YC separation apparatus according to the present invention uses an MTS type NTS separator.
When separating a luminance signal and a chrominance signal from a composite video signal down-converted into the C system, a natural number is set to n and the number of stages can be switched between 909 and 910; A switching device that can switch and output a signal delayed by n horizontal periods and a signal delayed by 2 × n horizontal periods to an output terminal, and input n composite video signals delayed by n or 2 × n horizontal periods. And a conventional color filter that outputs a color signal using the line correlation and outputs a luminance signal by adding or subtracting the color signal and a composite video signal with a delay. Only one line memory needs to be added, and the number of stages is switched in a coexistence system of PAL and NTSC which originally uses two-line correlation. Almost no increase in cost and easy since it is possible to cope with only.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a YC separation apparatus for separating a luminance signal and a chrominance signal from a composite video signal down-converted from the MUSE system to the NTSC system. A delay device capable of delaying an input composite video signal by 2 × n horizontal periods and outputting a signal delayed by 2 × n horizontal periods to an n-th output terminal; A comb filter device that receives a composite video signal as input, outputs a color signal using the line correlation thereof, and outputs a luminance signal by adding or subtracting the color signal and a composite video signal with a delay. A YC separation device characterized in that it is possible to perform YC separation of a composite video signal down-converted from the MUSE system to the NTSC system with a high degree of accuracy and using line correlation. Such an action can be performed YC separation with high precision MN composite signal by providing n-number of lines with optimal line correlation to comb filtering. According to a second aspect of the present invention, in the delay device according to the first aspect, the number of stages is 9
2 × n line memories capable of switching between 09 and 910, and a switching device capable of switching and outputting a signal delayed by n horizontal periods and a signal delayed by 2 × n horizontal periods to an nth output terminal 2. The YC separating apparatus according to claim 1, further comprising: a line filter having a line correlation optimum for a MN composite signal and a signal other than the MN composite signal for a comb filter using line correlation. By providing the n lines having the following expression, there is an effect that highly accurate YC separation of the MN composite signal can be performed. According to a third aspect of the present invention, there is provided a device for detecting a composite video signal down-converted from the MUSE system to the NTSC system, and the output of the switching device according to the second embodiment is switched by the output thereof. 2. The YC separation apparatus according to claim 1, wherein the MN composite signal and other signals are detected by a comb filter using line correlation, and n lines having optimum line correlations are detected. Has the effect of performing highly accurate YC separation of the MN composite signal. According to a fourth aspect of the present invention, in the detecting apparatus for a composite video signal down-converted from the MUSE system to the NTSC system according to the third embodiment, the number of sampling clocks locked to a burst in one frame period is counted. 2. The YC separation apparatus according to claim 1, wherein the MN composite signal and the other signals are detected by performing a clock count of one frame with respect to a comb filter using line correlation, and are optimally detected. N lines having high line correlation can be provided based on the detection result, so that highly accurate YC of the MN composite signal can be obtained.
It has the effect that separation can be performed. According to a fifth aspect of the present invention, the MUSE method according to the third aspect is changed to NT.
A detecting device for detecting a composite video signal down-converted to the SC system, counting an input clock, resetting the value once per frame, and holding the reset value immediately before resetting; A subtraction device that outputs a difference between an input value and a certain set value,
A first comparison device that receives the output of the subtraction device, compares the result with a certain set value, and outputs a result, and a second device that receives the output of the subtraction device, compares the result with a certain set value, and outputs the result. 2. The YC separation device according to claim 1, further comprising: a second comparison device; and an AND device that receives outputs of the first and second comparison devices and outputs a logical product. The MN composite signal and other signals are detected by performing a clock count of one frame with respect to the comb filter using the line correlation and comparing and calculating with a precision of a set value set to a certain value. Since n lines having line correlation can be provided based on the detection result, there is an effect that highly accurate YC separation of the MN composite signal can be performed. Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows a block diagram of a YC separation apparatus according to a first embodiment of the present invention. FIG.
In the figure, 101 is an input terminal to which an MN composite is input. 102 and 103 are line memories,
The number of stages is set to 909. 104 is a subtraction device, 10
Reference numeral 5 denotes an amplifier having a gain of ２, and reference numeral 106 denotes a band-pass filter (hereinafter, referred to as BPF) for band limitation.
The two components form a two-line comb filter. 107 is a subtraction device for extracting a luminance (Y) signal. 108 is a delay device for delay adjustment. This system operates with a quadruple burst clock locked to a burst of an input signal. The operation of the YC separation device configured as described above will be described below with reference to FIGS. First, FIG. 4 shows a signal waveform. A black circle is an example of a sampling point when sampling is performed at 4 f _SC . The signal input from 101 is the n-th line signal 10A, which is delayed by 909 sampling times (hereinafter referred to as 1 sampling time = 1T) in the line memory 102, and
0B. Further, the (n + 1) th line signal 10B is further delayed by 909T by the line memory 103, and
A line signal 10C is obtained. At this time, the phase of the C signal between the n-th line signal and the (n + 2) -th line signal is 4f _SC of 18
Since 18T is delayed, 1818/4 = 45 of f _SC
This results in a delay of 4.5 waves, and as a result, the phase is inverted. The Y signal is 4f _SC = 9 as described above.
1H = 909.09 since the value of _H. 09.09fH is satisfied.
T, and 2H = 1818.18. This gives 1
The phase of Y at the time of delay of 818T is only shifted by 0.18 clock, and an extremely good correlation can be obtained as compared with a normal line correlation. This relationship is shown in FIG. The n-th line signal 10A and the (n + 2) -th line signal 10C thus obtained are subtracted by 104, and the gain is reduced by １０５ by 105.
Then, a C signal 10E is obtained by passing through the BPF 106. The Y signal 107 is obtained by subtracting the obtained C signal 10E from 10G obtained by the delay device 106.

As described above, according to the present embodiment, 909T
By providing two line memories that can delay
It is possible to perform highly accurate YC separation of the MN composite signal.

(Embodiment 2) FIG. 2 shows a block diagram of a YC separation apparatus according to a second embodiment of the present invention. In FIG. 2, reference numeral 201 denotes an input terminal to which a composite video signal is input. Reference numerals 202 and 203 denote line memories which switch the number of delay stages between 909 and 910 according to a switching control input described later. 208 is a switching SW
The switching control is the same as the switching control input of the line memory. Reference numeral 204 denotes a subtractor, 205 denotes a 1/2 amplifier, and 210 denotes a BPF, which forms a comb filter as in the first embodiment. 206 is a subtraction device for extracting a luminance (Y) signal. Reference numeral 209 denotes an MN composite signal detection device, which determines that the input is an MN composite signal and controls the output based on the result. 211 is a delay device for delay adjustment.

The operation of the above-configured YC separation apparatus will be described below with reference to FIG.

In step 209, it is determined whether the input signal is an MN composite signal or a normal signal.
Output to According to the output of 20H, the number of delay stages of 202 and 203 is set to 909T for an MN composite signal and 910T for a normal signal. In addition, the signal 20D input to the comb filter device is switched between one line delay and two line delay by 208.

As a result, 20D is a two-line delay signal of 909T for an MN composite signal, and 91 D for a normal signal.
It becomes a one-line delay signal of 0T. Subsequent operations are the same as those in the first embodiment in the case of the MN composite signal, and a description thereof will be omitted. In the case of a normal signal, the YC separation operation is performed by the line correlation with the one-line delay signal as in the conventional case.
As described above, according to the present embodiment, the line memory capable of switching the number of delay stages to 909 and 910 by the control signal, the MN composite signal detection device for detecting the MN composite signal, and the input to the comb filter adaptively By providing the signal switching device, it is possible to coexist the highly accurate YC separation operation of the MN composite signal and the conventional YC separation operation of the normal signal in one system.

(Embodiment 3) FIG. 3 is a detailed block diagram of an MN composite detection device according to a second embodiment of the present invention. In FIG. 3, reference numeral 301 denotes an input terminal to which a clock signal locked to a burst is input. A counter 302 resets its value by a reset input. However, the output retains the value when reset. 303 is a subtraction device. 30
Reference numerals 4 and 305 denote comparison devices which compare the set value with the input value and output the result. 306
Is a two-input AND device and outputs a logical product. The operation of the MN composite detector configured as described above will be described below with reference to FIG.

At 302, the number of input clocks is counted. A frame reset pulse 30H, which generates a pulse once per frame, is input to 302 and reset. Since the value at this time is 1H = 910T as described above for a standard signal, 910 × 525 = 47.
7750. In the case of an MN composite signal, 1H =
Since it is 909.0908T, its value is 479273 (theoretical value). This value is output as 30A. The set value 30I is subtracted from the obtained value 30A by the subtraction circuit. If a standard time value of 477750 is set in 30I, 0 is output as the output signal 30B for the standard signal and -577 for the MN composite signal. 30B
Is compared with the set value 30F by the first comparison device 304, and outputs a logic “1” to the output 30C if the value is larger than 30F. Similarly, the second comparator 305 sets the set value 30
G is compared with G, and if it is smaller than 30G, a logical "1" is output to the output 30D. The AND of 30C and 30D is 30
By taking the value at 6, the output 30E is set to logic "1" if 30F <30B <30G. This 3
0F to a value slightly smaller than -477, and 30G to -4
If set to a value slightly larger than 77, MN
A composite signal can be detected. As described above, according to this embodiment, the input signal of the comb filter and the number of stages of the line memory are switched by providing the clock counter that counts the clock and the comparison device that evaluates the output with two set values. A control signal can be obtained, and an MN composite signal can be detected to increase the accuracy of YC separation. Note that the first and second
In the embodiment, the comb filter has a two-line correlation, but there is no problem with a comb filter using a correlation of three or more lines. In that case, two line memories are required every time one line input signal is increased.

[0015]

As described above, according to the present invention, a line memory capable of switching the number of delay stages to 909 and 910 by a control signal and an MN for detecting an MN composite signal are provided.
By providing a composite signal detection device and a device that adaptively switches the input signal to the comb filter, highly accurate YC separation of the MN composite signal can be performed, and the system can coexist with the normal signal system. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of a YC separation device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a YC separation device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating the operation of a YC separation device according to a third embodiment of the present invention.

FIG. 4 is an operation explanatory diagram in the first and second embodiments of the present invention.

FIG. 5 is a diagram illustrating the operation of YC separation.

FIG. 6 is an explanatory diagram of an operation in a conventional YC separation device.

FIG. 7 is a block diagram of a conventional YC separation apparatus.

[Explanation of symbols]

 101, 201, 301 Input terminal 102, 103, 202, 203 Line memory 104, 107, 204, 206 Subtractor 105, 205 1/2 gain amplifier 106, 210 BPF 208 Switching SW 209 MN composite discriminator 302 Counter 303 Subtractor 304, 305 Comparison device 306 AND device 701 Burst lock PLL device 702 Line lock PLL device 703 A / D device 704 Phase detection device 705 Frequency ratio detection device 706 Correction coefficient operation device 708 Com filter 709 Multiplier

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Moribe 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hitoshi Ando 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) GK02 5C066 AA03 BA02 BA18 CA01 CA07 CA08 DC02 EA03 EC13 EC14 GA02 GA04 GA05 GB01 KA12 KC04 KC06 KC11 KD06 KE02 KE07

Claims (5)

[Claims] 1. A YC separation device for separating a luminance signal and a chrominance signal from a composite video signal down-converted from a MUSE system to an NTSC system, wherein a natural number is n and an input composite video signal is delayed by 2 × n horizontal periods. A delay device capable of outputting a signal delayed by 2 × n horizontal periods to an nth output terminal, n composite video signals delayed by 2 × n horizontal periods, and an input composite video signal that is not delayed As an input, output a color signal using the line correlation,
A comb filter device for outputting a luminance signal by addition or subtraction of the color signal and the composite video signal with a delay, wherein the MUSE system has a high accuracy with less malfunctions.
YC of composite video signal down-converted to SC
A YC separation device capable of performing separation. 2. The delay device according to claim 1, wherein 2 × n line memories whose number of stages can be switched between 909 and 910, and a signal delayed by n horizontal periods to an n-th output terminal. 2. The YC separation device according to claim 1, further comprising: a switching device capable of switching and outputting a signal delayed by × n horizontal periods. 3. The apparatus according to claim 1, further comprising a detecting device for detecting a composite video signal down-converted from the MUSE system to the NTSC system, wherein the output of the switching device according to claim 2 is switched by the output. YC separation device. 4. The method according to claim 3, wherein
2. The YC separation apparatus according to claim 1, wherein the detection apparatus for the composite video signal down-converted to the SC system counts the number of sampling clocks locked to a burst in one frame period. 5. The MUSE system according to claim 3, wherein
A detecting device for detecting a composite video signal down-converted to the SC system, counting an input clock, resetting the value once per frame, and holding the reset value immediately before resetting; A subtraction device that outputs a difference between an input value and a certain set value,
A first comparing device that receives the output of the subtraction device and compares it with a certain set value and outputs H if the input value is larger, and receives the output of the subtraction device and compares it with a certain set value And a second comparison device that outputs H if the set value is larger, and outputs of the first and second comparison devices,
The YC separation device according to claim 1, further comprising an AND device that outputs a logical product.