JP2516004B2 - Color-video signal conversion method and apparatus thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color video signal conversion method and apparatus, and more particularly, to an original SECAM after converting a SECAM color video signal into a PAL color video signal for transmission. The present invention relates to a method for converting a color image signal into a system and a conversion device for realizing such conversion.

As is well known, the current color television system is not unified worldwide, and there are three systems, NTSC system, PAL system and SECAM system, depending on the color signal transmission form. It uses a television system. Among them, the PAL method and SECAM method have the same number of scanning lines and the same field frequency, and the countries to be adopted are adjacent or close to each other.

On the other hand, among the helical scan VTRs that record and reproduce current color video signals, the mainstream ones are obtained by separating the luminance signal and carrier color signal from the color video signal and frequency modulating the carrier wave with the luminance signal. The frequency-modulated luminance signal (FM luminance signal) and the low-frequency conversion carrier color signal obtained by frequency-converting the carrier color signal to the lower frequency side of the frequency band of the FM luminance signal are frequency-division-multiplexed, and this frequency is multiplexed. A so-called low frequency band is used in which a division multiplex signal is recorded on a magnetic tape by a rotary head, and the reproduction frequency division multiplex signal is subjected to signal processing reverse to that at the time of recording to obtain a reproduction color video signal of a predetermined color television system. It is well known that the conversion color recording / reproducing system is adopted.

In this low-frequency conversion color recording / playback VTR,
To improve tape use efficiency, two adjacent recording tracks are recorded and reproduced with no guard band or with a narrow guard band by rotating heads with different azimuth angles. The crosstalk from the adjacent track of the low-frequency converted carrier color signal deteriorates the image quality, so that some sort of crosstalk countermeasure processing is performed.

As a crosstalk countermeasure processing, the present applicant has already applied for a VTR that converts an NTSC color video signal or a PAL color video signal into the above-mentioned signal form and records / reproduces it.
As disclosed in Japanese Patent Publication No. 6-9073 and Japanese Patent Publication No. 55-32273, the color subcarrier of the low-frequency conversion carrier color signal, which is an amplitude-modulated wave, is moved 90 times in a certain direction every horizontal scanning period (1H). Recording is performed by shifting by °, and at the time of reproduction, a reproduction carrier color signal in which the color subcarrier is shifted by 90 ° in 1H increments is obtained in a direction substantially opposite to that at the time of recording, and the color signal is passed through a comb filter. The so-called PS that obtains the reproduced carrier color signal from which crosstalk has been removed
(Phase Shift) method is known.

However, in a VTR that converts a SECAM color video signal into the signal form described above and records and reproduces the signal, the carrier color signal in the SECAM color video signal is a frequency modulated wave, unlike those of the NTSC and PAL systems, and Since this is a signal obtained by frequency-modulating a carrier with a line-sequential color difference signal, the above-described PS method cannot be adopted. Therefore, the VT of the low-frequency conversion color recording / reproducing method for recording / reproducing the SECAM color video signal
In R, for example, as disclosed in Japanese Patent Publication No. 58-36876 by the present applicant, the carrier chrominance signal is frequency-down-recorded, and during reproduction, even if the reproduction low-frequency conversion carrier chrominance signal is frequency-multiplied. And the reproduced carrier chrominance signal of the frequency band and the frequency shift.

However, in the VTR that records and reproduces the SECAM system color video signal, especially in the long time mode in which the tape running speed is slowed to record and reproduce for a long time, the deterioration of the color edge is more noticeable than that of the PS system VTR described above. . Because of this, the SEC
It is preferable to convert the AM system color video signal into a PAL system color video signal and record / reproduce by the PS system because the reproduced color image quality is improved. In addition, a magnetic tape on which a PAL system color video signal is recorded can be reproduced as a SECAM system color video signal, which is desirable.

In view of this, SECAM system color video signals are also recorded and reproduced as PAL system color video signals on magnetic tape.
The TR recording system requires a conversion device that converts the SECAM system color video signal into a PAL system color video signal (especially the carrier color signal), and the playback system converts the playback PAL system color video signal to S
A conversion device for converting to an ECAM type color video signal (particularly a carrier color signal) is required.

2. Description of the Related Art A first conversion device for converting a SECAM-system carrier color signal into a PAL-system carrier color signal has conventionally been, for example, a 1H delay circuit for a carrier color signal in an input SECAM system color video signal and a 1H delay signal for its input / output signal. After being synchronized by a switch circuit for switching each of them, it is supplied to two FM demodulators in parallel and two types of color difference signals (RY) and (BY) which are synchronized by this are taken out in parallel, respectively. Further, with these two types of color difference signals, the PAL color subcarrier frequency 4.433619MHz (hereinafter referred to as 4.43MHz) is subjected to carrier-suppressed quadrature two-phase amplitude modulation, and the color subcarriers of the color difference signal (RY) are set every 1H. Phase inversion was performed and both signals were multiplexed to generate a carrier color signal conforming to the PAL system.

Further, a second conventional conversion device for obtaining a SECAM system color signal from a PAL system color signal is, for example, a color difference signal (BY) from a carrier color signal in an input PAL system color video signal.
And a color difference signal (R-
The second carrier color signal whose modulation signal is Y) is separated using a 1H delay circuit, an adder for adding the input / output signals of the 1H delay circuit, and a subtractor for subtracting the input / output signal of the 1H delay circuit. Then, the first carrier color signal is a color difference signal (B-
Y) frequency-modulates (FM) the 4.25MHz carrier and
An M-modulated wave is generated, while the second carrier color signal is phase-inverted every 1H and then AM demodulated to obtain a color difference signal (RY) of 4.40.
FM the carrier wave of 625MHz (hereinafter referred to as 4.41MHz)
After generating the FM modulated wave, the first and second FM modulated waves are alternately selected and output every 1H by the switch circuit, and SECA is performed.
It was configured to output as an M system carrier color signal.

Here, the color information of the carrier color signal in the input SECAM system color video signal of the first conversion device and the output of the first conversion device
Color information of PAL system carrier color signal and AM in the second converter
The color difference signal obtained by supplying the color information of the demodulated color difference signal and the SECAM system carrier color signal extracted from the second conversion device to a television receiver (hereinafter referred to as TV) and demodulating on the TV. The relative relationship with the color information of the above is summarized for each line (scanning line) as shown in FIG. In the figure,
“S → P” indicates the output PAL system carrier color signal of the first conversion device, and “after PAL demodulation” is the color difference signals (R−Y) and (B−Y) demodulated by AM in the second conversion device. ), “After SECAM demodulation on TV” indicates the color difference signal demodulated on the TV. Further, "R" indicates a color difference signal (RY), "B" indicates a color difference signal (BY), the numbers immediately before "R" and "B" indicate line numbers, and "R". Immediately after "0"
And “π” indicates that the carrier phase of the color difference signal (RY) is 0 °.
And the case of 180 ° are shown respectively (the same applies to FIG. 4).

As can be seen from FIG. 3, the two types of color difference signals (RY) and (BY) that are demodulated by AM in the second conversion device and taken out in parallel are the PAL system carriers from the first conversion device. Since the carrier color signal obtained by subtracting and adding the signal of the current input line number of the color signal and the signal one line before is AM demodulated, the column of "after PAL demodulation" in FIG. It becomes as shown in.

Here, the two types of color difference signals (RY) after this PAL demodulation
And (B-Y) in the second converter,
FM modulated, converted to line-sequential signal, and SECAM again
Although it is supplied to the SECAM system TV after being converted into a system-carried color signal, the color-difference signal surrounded by a square is selected as the color-difference signal forming the line-sequential color-difference signal in the column “after PAL demodulation” in FIG. In this case, the two types of color difference signals obtained by demodulating in the TV and the two types of color difference signals forming the carrier color signal in the input SECAM system color video signal of the first conversion device are:
The same color difference signal is generated on the same line (in other words,
(The first line of the first frame has the same kind of color difference signal as shown in FIG. 3). If a color difference signal not enclosed by a square is selected, different kinds of color difference signals may be obtained on the same line. You can see from Figure 3. When the former input / output is the same color sequence and the latter input / output is a different color sequence, if conversion is performed at random, each will occur with a probability of 50%.

However, conventionally, there is usually a correlation between the color sequence of the input SECAM type carrier color signal of the first conversion device and the phase of the color burst signal in the output PAL type carrier color signal. Since there is no correlation between the phase of the color burst signal in the input PAL system carrier color signal and the color sequence of the output SECAM system carrier color signal in the second conversion device, the above-mentioned two types of color sequences Occurs with a probability of 50%, and in this case, two kinds of states having different characteristics of line flicker and line flicker due to system conversion are caused in the vicinity of a portion where the hue suddenly changes after demodulation in the TV.

This will be described more specifically with reference to FIG.
Now, assuming that the image of the color video signal to be transmitted is red from the first line to the third line and blue from the fourth line to the 625th line in each frame, 1R, 2R and 3R are shown in FIG. The color difference signal (RY) indicated by 1 exists, which is referred to as "r", and the color difference signals (BY) indicated by 1B, 2B, 3B.
Does not exist (this is marked as "o"). Similarly, there is no color difference signal (RY) for each line indicated by 4R to 625R.
The color difference signal (BY) of each line shown by 625B exists (this is referred to as "b"). Therefore, when FIG. 3 is rewritten, it becomes as shown in FIG.

In FIG. 4, a portion surrounded by a broken line in the column of “after SECAM demodulation on TV” indicates a color flicker region that appears near a portion where the hues of the third line and the fourth line suddenly change.
This is a region where the amplitude is different from other regions of the same hue, and color bleeding appears to blink on the screen.

In FIG. 4, the column “after PAL demodulation” transmits the color difference signal enclosed by a square. The case where the input and output have the same color sequence and the color difference signal not enclosed by a square are transmitted. Comparing both flicker areas in the case of different color sequences of input and output, the flicker area width is 3 lines in the case of color sequences having the same input and output, and 2 lines in the case of color sequences having different inputs and outputs. In the same color sequence for output, the two types of color difference signals in the 6th line have small amplitudes r and b, whereas in the color sequence with different input and output, the two types of color difference signals in the 5th line are “2 × r”. , A large amplitude of “2 × b”.

Conventionally, as described above, the input and output were not intentionally set to a predetermined constant color sequence, so there is a 50% probability that two states with different bleeding line numbers and flicker characteristics will occur. There was a problem that it occurred.

The present invention was created in view of the above points, and it is an object of the present invention to provide a color video signal conversion method and apparatus capable of performing conversion such that input / output always becomes a color sequence having a predetermined relationship. And

Means for Solving the Problems A color video signal conversion method of the present invention comprises a first system conversion circuit for converting a carrier color signal in a SECAM system color video signal into a PAL system carrier color signal, and a PAL system carrier color. It comprises a transmission line for transmitting a signal and a second system conversion circuit for converting the PAL system carrier color signal into a SECAM system carrier color signal, and the first system conversion circuit is a color difference signal of the PAL system carrier color signal ( R-Y) and the color sequence in the SECAM system carrier color signal are fixed to either one of the two predetermined relationships, and the color difference signal (RY) is fixed.
The color sequence information is transmitted according to the polarity of the.

That is, two types of color difference signals that have been synchronized are extracted from the carrier color signal in the SECAM system color video signal, and they are modulated and added to generate a carrier color signal that complies with the PAL system and sent to the transmission path. Here, the phase of the first switching signal necessary for the above-mentioned synchronization and the phase of the carrier wave for each horizontal scanning period of the first and second modulated waves forming the PAL carrier color signal are A predetermined phase relationship is always established between the inverted carrier wave of the second modulated wave and the phase of the first control signal for performing the phase inversion.

The carrier color signal of the PAL system that has passed through the transmission line is
After being demodulated into two types of color difference signals, two types of frequency-modulated waves obtained by separately frequency-modulating two types of SECAM-compliant carrier waves with these two types of demodulated color difference signals are generated every horizontal scanning period. The signals are switched alternately and are taken out as SECAM system carrier color signals. A second control signal for inverting the phase of the second modulated wave or its demodulated color difference signal among the first and second modulated waves forming the PAL system carrier color signal every horizontal scanning period. And the second switching signal for switching between the two types of frequency-modulated waves is always in a predetermined phase relationship with the first control signal.

Further, the color video signal conversion device according to the third aspect of the invention claims that the carrier color signal in the SECAM system color video signal is 1
A 1H delay circuit for delaying a horizontal scanning period (1H), a first switch means for outputting two synchronized carrier color signals in parallel, and a first for outputting first and second color difference signals respectively in parallel Demodulating means, first modulating means for generating the first and second modulated waves, an adding circuit for outputting a PAL system carrier color signal, and a SECAM system carrier color signal. P
Second demodulation means for extracting the first and second demodulation color difference signals in parallel from the AL system carrier color signal, the second modulating means for generating the first and second frequency-modulated waves, and the SECAM system carrier color It is an apparatus which comprises a second switch means for outputting a signal and realizes the conversion from the PAL system to the SECAM system in the color video signal conversion method described in claim 1.

In the color video signal conversion method, the second control signal, the second
The switching signal and the first control signal are always kept in a predetermined phase relationship, and the color sequence of the original SECAM system carrier color signal before conversion to the PAL system carrier color signal and the converted PAL system It is possible to establish a predetermined relationship with the color sequence of the SECAM-type carrier color signal obtained by further converting the carrier color signal.

Here, when the color sequence of the original SECAM system carrier color signal before conversion and the color sequence of the SECAM system carrier color signal after conversion are to be set in a predetermined relationship,
Since the original SECAM system carrier color signal is converted to the PAL system carrier color signal and transmitted through a transmission path such as a recording medium,
The color sequence information of the SECAM type carrier color signal must be transmitted through the transmission path in some form.

A possible transmission method of the color sequence information is to transmit a pilot signal. That is, this method indicates, for example, by "1" or "0" whether the current line is the transmission line of the color difference signal (RY) or (BY) in the original SECAM type carrier color signal. This is a method of multiplexing a signal obtained by modulating a carrier wave by AM, FM or the like with the binary signal with a converted PAL system color video signal as a pilot signal and transmitting the multiplexed signal.

However, in this method, the number of transmission channels is increased by the amount of pilot signals. Therefore, for example, when a magnetic tape is used as the transmission path, the tape usage amount increases, and the PA
This is not desirable because the bandwidth of the L system color video signal is reduced and the image quality is slightly degraded.

On the other hand, according to the present invention, the above-mentioned color sequence information is carried to the phase of the second modulated wave modulated by the color difference signal (RY) of the converted PAL system carrier color signal. It is possible to prevent an increase in channels, prevent an increase in tape usage, and prevent deterioration of image quality.

Conventionally, as described above, when the SECAM method carrier color signal is converted to the PAL method carrier color signal, the color sequence information of the SECAM method carrier color signal is transferred to the subsequent PAL method carrier color signal.
There is no intention to transfer to the AM system conversion stage, and when converting the PAL system carrier color signal to the SECAM system, such color sequence information is received, and the SECAM system carrier color signal after conversion is received based on the color sequence information. I'm not trying to control the color sequence. Therefore, the conventional conversion method cannot link the color sequences of both the SECAM system before conversion and the SECAM system after conversion and the intention thereof.

By linking both color sequences, the present invention has a 50% probability of not linking them.
In order to prevent the generation of color images of different types and to transmit the color sequence information for linking, the phase of the carrier wave of the second modulated wave in the converted PAL system carrier color signal is used. There are features.

Next, in the converter for converting the SECAM system carrier color signal into the PAL system carrier color signal, the input carrier color signal and the output carrier color signal of the 1H delay circuit are generated by the first switching means based on the discrimination signal. The first and second signals are supplied to the first demodulating means after being converted into two carrier color signals which are switched by every one horizontal scanning period by one switching signal and are synchronized with each other. The second color signals are respectively taken out in parallel.

The first and second color difference signals are supplied to the first modulating means, where the first color difference signal is the first of the first and second carrier waves that are 90 ° out of phase with each other according to the PAL method. A carrier wave is amplitude-modulated to be a first modulated wave, and
The second color difference signal amplitude-modulates the second carrier wave, and the phase of the second carrier wave is one horizontal scanning period by the first control signal which is always in a predetermined phase relationship with the first switching signal. The second modulated wave is inverted every time. These first and second modulated waves are added and synthesized by the adder circuit and then output as a PAL system carrier color signal. Therefore, the transmission order of the color difference signals in the input carrier color signal of the SECAM system and the phase of the carrier wave of the second modulated wave in the output PAL system carrier color signal (in other words, the phase of the color burst signal) are always predetermined. It will be output after being specified by the relationship.

Further, the PAL system carrier color signal is supplied to the second demodulation means, the first and second modulated waves are respectively demodulated, and the second modulated wave or the demodulated color difference signal thereof is a color burst signal phase. The phase inversion is performed every horizontal scanning period by the second control signal obtained from the above, whereby the first and second demodulated color difference signals are obtained.

These first and second demodulated color difference signals are supplied to the second modulation means, where the two types of carrier waves complying with the SECAM system are frequency-modulated separately to form first and second frequency-modulated waves. After being converted, it is supplied to the second switch means, where the second control signal has a predetermined phase relationship with the second control signal.
Are alternately selected and output every horizontal scanning period.

As a result, the SECAM-system carrier color signal in which the phase of the carrier wave of the second modulated wave in the input PAL-system carrier color signal and the predetermined color sequence are always maintained is taken out from the second switch means. Therefore, the phase of the carrier wave of the second modulated wave in the input PAL carrier color signal and its original SECAM
The color sequence of the carrier color signal of the method is kept constant, and if it is known, both the color sequence of the original SECAM method carrier color signal before conversion and the output SECAM method carrier color signal after conversion are set. Can be constant.

Embodiment FIG. 1 shows a block system diagram of an embodiment of an essential part of a method of the present invention for converting a SECAM system carrier color signal into a PAL system carrier color signal and an apparatus thereof. In the figure, the carrier color signal in the SECAM type color video signal that has entered the input terminal 1 is supplied to the terminal 3a of the switch circuit 3 through the 1H delay circuit 2, and immediately after that is supplied to the switch circuit 3 to 3b. At the same time, the discrimination signal is supplied to the discrimination signal demodulator 4, and the discrimination signal transmitted every predetermined period in the SECAM system carrier color signal is demodulated here.

The output signal of the discrimination signal demodulator 4 is supplied to a waveform shaping circuit 5, where, for example, a color difference signal (R-
In the transmission line of Y), a high level, color difference signal (BY)
Is applied to the data input terminal of the D-type flip-flop 6 after being shaped into a low-level square wave inverted every 1H. On the other hand, a horizontal synchronizing signal separated and output from the luminance signal in the SECAM type color video signal by a known means is applied to the clock terminal CK of the D-type flip-flop 6 via the input terminal 7. As a result, from the D-type flip-flop 6, the color difference signal (R-
Y) and (BY) have different levels for each transmission line 2
A square wave of values is taken. The two square waves output from the D-type flip-flop 6 to the switch circuit 3 and the switch circuit 14, which will be described later, are inverted every 1H, and their relative phases are always maintained in a constant phase relationship.

The switch circuit 3 is applied with a square wave from the D-type flip-flop 6 as a switching signal, and a first frequency-modulated wave (FM modulated wave) in which an input SECAM carrier color signal is modulated by a color difference signal (BY). During the 1H period, the input carrier color signal is selectively output from the common terminal 3c, the output carrier color signal of the 1H delay circuit 2 is selectively output from the common terminal 3d, and the second carrier signal modulated by the color difference signal (RY) is output. FM modulated wave is input terminal 1
In the next 1H period, the output is switched alternately every 1H so that the output carrier color signal of the 1H delay circuit 2 is selectively output from the common terminal 3c and the input carrier color signal is selectively output from the common terminal 3d. Controlled.

Thereby, carrier color signals, which are two types of FM modulated waves having different carrier frequencies, are taken out in parallel from the common terminals 3c and 3d of the switch circuit 3, and are separately outputted to the SECAM demodulators 8 and 9. It is supplied and FM demodulated here. As a result, a color difference signal (BY) is extracted from the SECAM demodulator 8, and at the same time, a color difference signal (RY) is extracted from the SECAM demodulator 9. These two kinds of synchronized color difference signals (BY) and (RY) are separately supplied to the PAL modulators 10 and 11, in which the frequency supplied by the 4.43 MHz oscillator 12 is 4.43 MHz. Identical to MHz and out of phase with each other 9
Two types of carriers different in 0 ° are subjected to carrier suppression amplitude modulation separately.

The output modulated wave of the PAL modulator 11 is phase-inverted by the inverter 13 and then supplied to the terminal 14a of the switch circuit 14, while being directly supplied to the terminal 14b of the switch circuit 14. The switch circuit 14 is switched and controlled by the square wave from the D-type flip-flop 6 so as to alternately select and output the input modulated waves of the terminals 14a and 14b every 1H.

As a result, the phase of the carrier wave is 1H from the switch circuit 14.
A second modulated wave, which is inverted every time, is taken out and supplied to the adder circuit 15 at the next stage, where the second modulated wave is shared with the first modulated wave from the PAL modulator 10 and output to the output terminal 16 after being band-multiplexed. Is output. The signal output to the output terminal 16 is a carrier color signal conforming to the PAL system, and a PAL color burst signal generated by a known means (not shown) is multiplexed in a predetermined section, for example, the carrier of the aforementioned VTR. It is supplied to a color signal recording system.

Thus, according to the present embodiment, the switch circuit 3 and the
14 is switched by two kinds of square waves having a fixed phase relationship with each other, the transmission order of the color difference signal in the input SECAM carrier color signal at the input terminal 1 and the output second modulated wave of the switch circuit 14 And the color burst signal phase are always kept in a predetermined specific relationship.

Next, another embodiment of the method of the present invention for converting a PAL system carrier color signal into a SECAM system carrier color signal and an embodiment of the apparatus will be described with reference to the block system diagram of FIG. In the figure, the PAL output from the output terminal 16 is input to the input terminal 18.
The carrier color signal in the system color video signal comes in via a recording system and a reproducing system of a magnetic tape, for example. The input PAL type carrier color signal is supplied to the adder circuit 20 and the subtractor circuit 21 through the 1H delay circuit 19, respectively, and is also supplied to the adder circuit 20 and the subtractor circuit 21 without being delayed. As a result, of the first modulated wave in which the carrier phase is always constant and the second modulated wave in which the carrier phase is inverted every 1H, which constitutes the PAL carrier color signal, Modulated wave is extracted from the adder circuit 20, and the second modulated wave is subtracted from the adder circuit 20.
Taken out from 21.

Further, the PAL system carrier color signal is supplied to the burst gate circuit 22, where the color burst signal is separated and extracted and supplied to the discrimination signal generator 23, and by discriminating its phase, the PAL system carrier color signal A discrimination signal for discriminating the phase of the carrier wave of the second modulated wave is generated. This discrimination signal is applied to the data input terminal of the D-type flip-flop 24. In the D-type flip-flop 24, the horizontal synchronizing signal separated and extracted from the luminance signal in the input PAL system color video signal by a known means is applied to the clock input terminal CK through the terminal 25, so that the discrimination signal is output from the output terminal. It outputs a square wave that inverts every 1H as if it was sampled with the horizontal sync signal.

Therefore, the square waves always have a constant relative phase relationship with each other. One square wave is applied to the switch circuit 27 as a switching signal, and the other square wave is applied to the switch circuit 32 described later as a switching signal. Based on the square wave, the switch circuit 27 alternately selects and outputs the second modulated wave extracted from the subtraction circuit 21 and the signal obtained by passing the second modulated wave through the inverter 26 every 1H.
As a result, the phase of the carrier wave from the switch circuit 27 becomes H.
Then, the second modulated wave that is always constant is extracted.

The PAL demodulators 28 and 29 in which the first modulated wave from the adder circuit 20 and the second modulated wave output from the switch circuit 27 correspond separately
To the color difference signals (BY) and (RY) by AM demodulation. Color difference signal (B
-Y) is supplied to the SECAM modulator 30, where the carrier of 4.25 MHz is frequency-modulated and converted into a first FM modulated wave. At the same time, the color difference signal (RY) is transferred to the SECAM modulator 31.
The carrier wave of 4.41 MHz is frequency-modulated and converted into the second FM modulated wave.

The switch circuit 32 is switched by the square wave from the D-type flip-flop 24, and alternately outputs the above-mentioned first and second FM modulated waves to the output terminal 33 every 1H. As a result, the carrier color signal conforming to the SECAM system is taken out to the output terminal 33.

Here, the switching phase of the switch circuit 32 and that of the switch circuit 27 are held in a predetermined phase relationship, and the switching phases of the switch circuits 3 and 14 are also set in a predetermined phase relationship. The color sequence of the SECAM type AM carrier color signal input to the input terminal 1 and the color sequence of the SECAM type carrier color signal output to the output terminal 33 have a predetermined relationship.

The present invention is not limited to the above-mentioned embodiment, and includes various other modifications. For example, the circuit section including the inverter 13 and the switch circuit 14 in FIG. 1 may be inserted between the SECAM demodulator 9 and the PAL modulator 11, or the circuit section may be connected to the PAL from the 4.43 MHz oscillator 12.
It may be provided in the carrier wave transmission path reaching the modulator 11. Also,
The PAL demodulator 29 in FIG. 2 may be provided between the output end of the subtraction circuit 21 and the input ends of the inverter 26 and the switch circuit 27, or the 1H delay circuit 19, the addition circuit 20 and the subtraction circuit 21.
One PAL demodulator may be provided at the common input terminal of.

Further, the present invention is particularly suitable for application to the PS type VTR described above, but is not limited to this, and it is needless to say that the present invention is also applicable to other VTRs, recording media such as disks, and other transmission paths. is there.

EFFECTS OF THE INVENTION As described above, according to the present invention, the transmission order of the color difference signals in the input carrier color signals of the SECAM system and the conversion order thereof are obtained.
It is possible to always set a fixed relative phase relationship with the color burst signal phase in the PAL system carrier color signal.
When converting the L-type input carrier color signal to the SECAM-type carrier color signal, the color burst signal phase in the PAL-type carrier color signal and the transmission order of the color-difference signals in the output SECAM-type carrier color signal are predetermined relative to each other. It is possible to set the phase relationship, and as described above, both the color sequences of the original SECAM method carrier color signal and the final converted output SECAM method carrier color signal can always have a predetermined fixed relationship, so that the hue is You can always obtain images with the same characteristics for bleeding and flicker in the vicinity of rapidly changing images.
Conversion from M system carrier color signal to PAL system carrier color signal, and
Conversion from the PAL system transport color signal to the SECAM system transport color signal can be performed without the need for special signals, and it is possible to prevent image quality deterioration due to increased tape consumption and transmission band reduction. It has features.

[Brief description of drawings]

FIG. 1 is a block system diagram showing an embodiment of the main part of the method of the present invention and its apparatus, and FIG. 2 is a block system diagram showing another embodiment of the main part of the method of the present invention and the embodiment of the device. The figure shows the relative relationship between the color information in each process when the carrier color signal is converted in the order of SECAM system, PAL system, and SECAM system, and the demodulated color information in the television receiver to which the final output SECAM system carrier color signal is supplied. And FIG. 4 is a diagram showing a specific example of FIG. 1 …… SECAM type carrier color signal input terminal, 2,19 …… 1H delay circuit, 3,14,27,32 …… switch circuit, 4 …… discrimination signal demodulator, 6,24 …… D type flip-flop, 7,25 …… Horizontal sync signal input terminal, 8,9 …… SECAM demodulator, 10,11 …… PAL modulator, 12 …… 4.43MHz oscillator, 13,26 …… Inverter, 1
5, 20 …… Adder circuit, 16 …… PAL system carrier color signal output terminal, 18 …… PAL system carrier color signal input terminal, 21 …… Subtraction circuit, 22 …… Burst gate circuit, 28, 29 …… PAL demodulation vessel,
30, 31 SECAM modulator, 33 SECAM type carrier color signal output terminal.

Claims (3)

(57) [Claims] A carrier color signal in a SECAM color video signal is converted into a PAL carrier color signal, and the polarity of a color difference signal (RY) in the PAL carrier color signal and the SECAM color are determined. The color sequence information is fixed to one of the two types of relationships existing between the color sequence of the carrier color signal in the video signal and the color sequence information.
A first system conversion circuit for transmitting and outputting depending on the polarity of the color difference signal (RY) in the L system carrier color signal; and a transmission line for transmitting the output PAL system carrier color signal of the first system conversion circuit, The PAL system carrier color signal from the transmission line is supplied, and the PAL system carrier color signal is converted into a SECAM system carrier color signal, and the sequence information is detected from the vector of the color burst signal in the PAL system carrier color signal. A second system conversion circuit for outputting a SECAM system carrier color signal in which a color sequence is fixed in a predetermined relationship with a polarity of a color difference signal (RY) of the PAL system carrier color signal. Color video signal conversion method. 2. The color video signal conversion method according to claim 1, wherein a magnetic recording medium is used as the transmission path. 3. A 1H delay circuit for delaying a carrier color signal in a SECAM system color video signal for one horizontal scanning period, and an input carrier color signal and an output carrier color signal of the 1H delay circuit,
First switch means for switching in parallel each of the two carrier color signals which are switched every horizontal scanning period by the first switching signal generated based on the discrimination signal, and the first switch means are connected in parallel. First demodulation means for separately frequency-demodulating the two carrier color signals taken out to output the first and second color difference signals in parallel, and the first color difference from the first demodulation means. The first carrier wave is amplitude-modulated from the first carrier wave of the first and second carrier waves that are 90 ° out of phase with each other in accordance with the PAL method, and a second modulated wave is generated by the second color difference signal. The second carrier wave is amplitude-modulated, and the phase of the second carrier wave is inverted every horizontal scanning period by the first control signal which is always in a predetermined phase relationship with the first switching signal. Second
A first modulating means for generating a modulated wave of the above, and an adding circuit for adding and synthesizing the first and second modulated waves by the first modulating means and outputting a PAL system carrier color signal to a transmission line. , The PAL system carrier color signal obtained by system conversion of the SECAM system carrier color signal is supplied from the transmission line, and the first modulated wave and the one horizontal scanning period constituting the PAL system carrier color signal The second modulated wave in which the phase of the carrier wave is inverted every time is demodulated, and the second modulated wave or the demodulated color difference signal thereof is made horizontal by the second control signal obtained from the color burst signal phase. Second demodulating means for inverting the phase for each scanning period to extract the first and second demodulated color difference signals in parallel, and two kinds of SECAM-compliant carrier waves for the first and second demodulated color difference signals separately. Second demodulation means for frequency demodulating to first and second frequency-modulated waves and , A second switching signal that is always in a predetermined phase relationship with the second control signal causes the first
And the second frequency-modulated wave are alternately selected and output, and the SE
A color video signal conversion device comprising: second switch means for outputting a SECAM type carrier color signal of a color sequence having a predetermined relationship with a color sequence of a CAM type carrier color signal.