JPS6159994A - Video tape recorder - Google Patents

Abstract

PURPOSE:To prevent the color saturation factor of an SECAM signal from lowering by alternating the increment factor of burst in the SECAM signal and that in a PAL signal when the SECAM signal is converted into a pseudo PAL signal for recorded and regeneration. CONSTITUTION: The PAL or SECAM signals are supplied to an input terminal 11 as image signals to be recorded. The image signals are supplied to the P terminal of a switch 12 as well as a SECAM/pseudo PAL conversion circuit 20. In the SECAM/pseudo PAL conversion circuit 29,the SECAM signals are converted into pseudo PAL signals, which are supplied to the Q terminal of a switch 12. Then a PAL/SECAM determination circuit 13 determines whether input image signals are PAL signals or SECAM signals. According to the result, the switch 12 is exchanged and also the increasing level of burst signal in a burst emphasis circuit 47 is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video tape recorder capable of selectively recording and reproducing PAL signals and SECAM signals.

The conventional SIECAM signal is that subcarriers with different frequencies for blue and red color difference signals are FM-modulated line-sequentially. Although the method is different from that of the PAL signal which is AM modulated, the line frequency and field frequency are the same as the PAL signal. Therefore, a method has been considered in which the SECAM signal is recorded as a color video signal on a magnetic tape by a PAL video tape recorder by converting the SECAM signal.

However, conventionally, line-sequential F'M modulated color signals for the blue and red color difference signals of the SECAM signal are converted into PAL signals.
Similar to the carrier color signal of the signal, the blue and red color difference signals are synchronized and converted into an AM-modulated color signal, and a burst signal similar to the burst signal of the PAL signal is added to this signal. Therefore, the conventional video signal conversion device connected to the PAL video tape recorder for the above purpose requires a delay circuit with a one-line delay time for synchronizing the blue and red color difference signals, and this delay circuit This has the disadvantage that the cost of the device is high because it is expensive.

Therefore, the line-sequential FM modulated color signals for the blue and red color difference signals of the SECAM signal are demodulated to obtain line-sequential baseband color signals for the blue and red color difference signals, and the line-sequential baseband color signals are obtained for the blue and red color difference signals. (The blue color difference signal is the first phase axis corresponding to the modulation axis of the blue color difference signal in the PAL signal, and the red color difference signal is relative to the first phase axis. AM modulation is performed on a second phase axis that is shifted by 90 degrees from each other to obtain line sequential AM modulated color signals for the blue and red color difference signals on modulation axes that are 90 degrees different from each other. It is conceivable to convert the SECAM signal into a video signal that can be called a pseudo PAL signal by adding burst signals having different phases as blue and red color difference signals to the color signal.

Problems to be Solved by the Invention As described above, a video signal conversion device that can be called a SECAM/pseudo-PAL conversion circuit, which converts a SECAM signal into a pseudo-PAL signal, can be configured as an adapter to convert an existing PAL video tape recorder. If connected to SECAM
The signal can be recorded as a color video signal on magnetic tape in a PAL video tape recorder.

However, in this case, the SECΔM/pseudo-PAL conversion circuit uses demodulated line-sequential blue and red color difference signals.
Although a stable oscillation circuit such as a crystal oscillation circuit that generates a subcarrier whose modulated frequency is equal to the subcarrier frequency of the PAL signal is required, and a delay circuit with a delay time of one line is not required. Note that the SECAM/pseudo-PAL conversion circuit as a video signal conversion device has a complicated configuration and is expensive.

In addition, since the pseudo PAL signal obtained from the SECAM/pseudo PAL conversion circuit described above is line sequential for the blue and red color difference signals, it is recorded and played back in a PAL video tape recorder and then color demodulated in a PAL television receiver. When the signals are synchronized and averaged in a circuit, there is a disadvantage that the degree of color saturation is lower than in the case of PAL signals.

In view of the above points, the present invention integrates a SECAM/pseudo-PAL conversion circuit as a video signal conversion device to provide an SEC
There is no need for a special oscillation circuit that generates subcarriers that are AM-modulated with line-sequential blue and red color difference signals that are demodulated during conversion from AM signals to pseudo-PAL signals, and the configuration is significantly simplified. In addition, the SECAM signal becomes a pseudo PA
The present invention proposes a new video tape recorder that suppresses a decrease in color saturation when the signal is converted to an L signal, recorded and played back, and displayed on a PAL television receiver.

Means for Solving the Problems In the present invention, the intensity signal of the PAL signal is FM-modulated to enhance the burst signal, and the frequency at which the fastest color signal including the burst signal is obtained from the oscillation circuit is the sub-frequency of the PAL signal. A SECAM/pseudo PAL conversion circuit is provided on the input side of the recording system that performs low frequency conversion using a frequency conversion carrier wave formed based on a reference carrier wave that is equal to the carrier wave frequency, and when the signal to be recorded is a PAL signal, the PAL signal is If the signal to be recorded is a SECAM signal, the SECAM/pseudo PΔ is supplied from the SECAM signal to the recording system.
The pseudo PAL signal converted by the L conversion circuit is supplied to the recording system, and the line sequential blue and red color difference signals demodulated by the SECAM/pseudo PAL conversion circuit are
The reference carrier obtained from the above-mentioned oscillation circuit of the recording system is used as the M-modulated subcarrier. Also, the reinforcement of the verse 1 signal in the recording system is performed using SECA in the recording system.
When the pseudo PAL signal obtained from the M/pseudo PAL conversion circuit is supplied, it is suppressed compared to when the PAL signal is supplied.

In the present invention, the FM-modulated signal of the PAL signal or pseudo-PAL signal reproduced from the magnetic tape is demodulated, and the carrier color signal is automatically gain-controlled based on the burst signal. A reproducing system is installed on the output side of a reproducing system that converts the carrier color signal back to its original frequency using a frequency converting carrier wave formed based on a reference carrier wave whose frequency obtained from an oscillation circuit is equal to the subcarrier frequency of the PAL signal. a signal selection processing circuit that obtains synchronized AM-modulated blue and red color difference signals from the output carrier color signal and the carrier color signal delayed by one line;
A color demodulation circuit that demodulates the AM-modulated blue and red color difference signals output from the signal selection processing circuit by synchronous detection to obtain baseband blue and red color difference signals is provided, and the above-mentioned color difference signals of the reproduction system are provided. The reference carrier obtained from the oscillation circuit is used as a subcarrier for synchronous detection of blue and red color difference signals in the color demodulation circuit.

Effect As described above, when the pseudo PAL signal obtained from the SECAM/pseudo PΔL conversion circuit is supplied to the recording system and recorded, if the enhancement of the burst signal in the recording system is suppressed, the burst of the carrier color signal in the reproduction system is suppressed. Since the AM modulated line sequential blue and red color difference signals are enhanced by signal-based automatic gain control, so-called ACC, when they are synchronized and averaged in the color demodulation circuit of a PAL television receiver. The decrease in color saturation can be suppressed to some extent. By the way, it is possible to reduce the amplitude of the burst signal when adding the burst signal in the SECAM/pseudo-PAL conversion circuit, but if this is done, the line AM modulated by ACC before the recording system burst signal is strengthened. There is an inconvenience that the successive blue and red color difference signals are intensified and the level ratio of the lung intensity signal and color signal recorded on the breath tape does not reach the desired ratio.

Embodiment FIG. 1 shows an example of the input system and recording system of the video tape recorder of the present invention, and FIG. 2 shows an example of the playback system and output system of the video tape recorder of the present invention. The input system is on the right, the recording system is on the right, the playback system is on the left of the dashed line 2 in Figure 2, and the output system is on the right.The recording and playback systems, with some exceptions, are the same as those of a normal PAL video tape recorder. Same.

First, to explain an example of the input system and recording system shown in FIG.
An AL signal or a SECAM signal is provided. This video signal to be recorded is supplied to the terminal P of the switch 12 on the one hand, and to the SECAM/pseudo-PAL conversion circuit 20 on the other hand. In the SECAM/pseudo-PAL conversion circuit 20, when the video signal to be recorded is a SECAM signal, the SECAM signal is converted into a pseudo-PAL as described later.
The signal is converted into a pseudo PAL signal, and the pseudo PAL signal is supplied to the terminal Q of the switch 12. The video signal to be recorded from the input terminal 11 is also supplied to the PAL/SECAM discrimination circuit 13, and the PAL/SECAM discrimination circuit 13 determines whether the video signal to be recorded is a PAL signal or not.
It is determined whether the video signal to be recorded is an AM signal, and a determination signal having a different level is obtained from the PΔL/SECAM determination circuit 13 depending on whether the video signal to be recorded is a PAL signal or a SECAM signal. The discrimination signal output from this PAL/SECAM discrimination circuit 13 is supplied to the switch 12 as a switching control signal, and when the video signal to be recorded is a PAL signal, the switch 12 is switched to the P side. The PAL signal to be recorded is taken out from the SECA 12, and the video signal to be recorded is taken out from the SECA
When it is the M signal, the switch 12 is switched to the terminal Q side, and the SECAM/pseudo PAL conversion circuit 20 takes out from the switch 12 a pseudo PAL signal converted from the SECAM signal to be recorded.

Conversion from a SECAM signal to a pseudo PAL signal in the SECAM/pseudo PAL conversion circuit 20 is performed as follows. That is, the SECAM signal is supplied to the SECAM decoder 21, FM-modulated line-sequential blue and red color difference signals of the SECAM signal are demodulated, and the demodulated line-sequential blue and red color difference signals are sent to the balanced modulation circuit. 22, a subcarrier whose frequency is equal to the subcarrier frequency of the PAL signal and whose phase differs by 90 degrees from the blue and red color difference signals is AM-modulated with the demodulated line sequential blue and red color difference signals. The AM modulated line sequential blue and red color difference signals are supplied to the burst adding circuit 23, and the AM
A burst signal having a frequency equal to the subcarrier frequency of the PAL signal and a phase different from the blue and red color difference signals is added to the modulated line sequential blue and red color difference signals. In this case, the subcarrier AM-modulated in the balanced modulation circuit 22 and the burst signal added in the burst addition circuit 23 have a frequency equal to the subcarrier frequency of the PAL signal obtained from the crystal voltage controlled oscillation circuit 31, as described below. A carrier wave with a certain r S =4.43 MHz is used.

In the recording system, the PAL signal or pseudo-PAL signal output from the switch 12 is supplied to a low-pass filter 41 to extract a tumor intensity signal, and the tumor intensity signal is supplied to a luminance signal recording processing circuit 42 where it is FM modulated. The FM-modulated luminance signal is extracted through a bypass filter 43 and supplied to a synthesis circuit 44.

In addition, the PAL signal or pseudo PA output of the switch 12
The L signal is supplied to the bandpass filter 45 -r, PA
The carrier color signal of the L signal or pseudo-PAL signal is extracted. The carrier color signal of the PAL signal is as shown in Fig. 3.
On every other line, the blue color difference signal is AM modulated on the B-Y axis and
1 for the B-Y axis for the M-modulated red color difference signal.
A burst signal F3 p with a phase advanced by 35 degrees is added,
On the other every other line, the blue color difference signal is AM-modulated on the B-Y axis, and the A signal is on the phase axis delayed by 90 degrees with respect to the B-Y axis.
1 for the B-Y axis for the M-modulated red color difference signal.
A burst signal Bm whose phase is delayed by 35 degrees is added. On the other hand, as shown in FIG. 4, for example, in every other line, the carrier color signal of the pseudo PAL signal is B-
A burst signal Bp with a phase that is 135 degrees ahead of the Y axis is added, and on every other line, a red color difference signal that is AM modulated with a phase that is 90 degrees behind the B-Y axis is added. A burst signal Bm having a phase delayed by 135 degrees with respect to the BY axis is added.

This carrier color signal is supplied to an ACC circuit 46 and subjected to automatic gain control based on the burst signal, and the controlled carrier color signal is supplied to a burst emphasis circuit 47 to enhance the burst signal.

Here, the discrimination signal output from the PAL/SECAM discrimination circuit 13 described above is supplied to the burst emphasis circuit 17 as a control signal for the degree of enhancement, and the video 13 to be recorded is
If the signal is a PAL signal and the PAL signal is supplied to the recording system, the burst signal will be doubled, and if the video signal to be recorded is a SECAM signal, the recording system will perform SECAM/pseudo-PAL conversion. When the pseudo P8 signal obtained from the circuit 20 is supplied, the burst signal is 1.
It is enhanced by about 65 times.

The carrier color signal whose burst signal has been enhanced in this manner is supplied to the frequency conversion circuit 48 and subjected to low frequency conversion. That is, the luminance signal obtained from the low-pass filter 41 is supplied to the horizontal synchronization signal separation circuit 32 to extract the horizontal open jlJ] signal, and the horizontal synchronization signal is supplied to the P-LL multiplier circuit 33 to determine the horizontal frequency of the PAL signal. For example, fc = 688, which is the subcarrier frequency after low-pass conversion with a constant relationship to
A kHz carrier wave is obtained, and the carrier wave is supplied to the frequency conversion circuit 34, and the above-mentioned crystal voltage controlled oscillation circuit 3.
1, the carrier wave whose frequency is set to f S =4.43 MHz, which is the subcarrier frequency of the PAL signal, as described later, is supplied to the frequency conversion circuit 34, and the frequency is changed from the frequency conversion circuit 34 through the bypass filter 35 to r.
A carrier wave for frequency conversion of s + f c =5.12 MHz is obtained, and this carrier wave for frequency conversion is transmitted to the phase control circuit 3.
6 and is phase-controlled for eliminating crosstalk from adjacent trunks during reproduction of the carrier color signal in the case of high-density recording, and the controlled carrier wave for frequency conversion is supplied to the frequency conversion circuit 48. The carrier color signal is low-pass converted so that the subcarrier frequency becomes fc=688kHz.

Here, the carrier color signal output from the ACC circuit 46 before low frequency conversion is supplied to the burst gate circuit 37 to extract the burst signal, and the extracted burst signal is supplied to the phase comparator circuit 38 to crystallize the crystal. Voltage controlled oscillation circuit 3
The phase is compared with the carrier wave obtained from 1, and the phase comparison circuit 3
The APC (automatic phase control) error voltage Vp of the output of the switch 39 is supplied to the terminal P of the switch 39, and the constant voltage Vc is supplied to the terminal Q of the switch 39. And the aforementioned PAL
The discrimination signal output from the /SECAM discrimination circuit 13 is supplied to the switch 39 as a switching control signal, and when the video signal to be recorded is a PAL signal and the PAL signal is supplied to the recording system, the switch 39 is connected to the terminal. tfA is turned off to the P side, and the APC error voltage Vp is applied to the crystal voltage controlled oscillation circuit 3.
1, the oscillation frequency of the crystal voltage controlled oscillation circuit 31 is controlled, and the video signal to be recorded is
When the pseudo-PAL signal obtained from the S-CAM/pseudo-PAL conversion circuit 20 is supplied to the recording system in the case of C8M, the switch 39 is switched to the terminal Q side and the constant voltage V
By supplying c to the crystal voltage controlled oscillation circuit 31, the oscillation frequency of the crystal voltage controlled oscillation circuit 31 is fixed exactly to the subcarrier frequency of the PAL signal, as described above.

The carrier color signal subjected to low frequency conversion in the frequency conversion circuit 48 is extracted through a low-pass filter 49 and supplied to the synthesis circuit 44 . Then, in the synthesis circuit 44, the FM
The modulated precision signal and the low frequency converted carrier color signal are combined, and the combined signal is supplied to the rotary magnetic heads 52 and 53 through the recording amplifier circuit 51.
2 and 53, tracks are recorded on the magnetic tape by alternately forming tracks that are inclined with respect to the running direction of the magnetic tape for each field.

Here, on the magnetic tape, as shown by the phase of the burst signal in FIG.
Regarding the pseudo PAL signal converted from the AM signal, B
- Burst signal Bp with a phase advanced by 135 degrees with respect to the Y axis
The line to which Bm is added and the line to which the burst signal Bm with a phase delayed by 135 degrees with respect to the BY axis is added, respectively, are tigers.

The colors are recorded in a state where the colors are not arranged in a direction perpendicular to the direction in which the colors extend.

Therefore, in the case of variable speed playback, when the rotating magnetic head diagonally traverses the track as shown by arrow 5, as shown by the phase of the burst signal in Figure 6, each time the rotating magnetic head moves from one track to the adjacent track. The line sequential aspect of the reproduced conveyed color signal will be disrupted.

An example of the reproduction system and output system shown in Fig. 2 will be explained as follows.
In the reproduction system, signals alternately reproduced from the magnetic tape by the rotating magnets 52 and 53 are supplied to an amplification and synthesis circuit 54, where they are amplified and synthesized into one signal. The output signal of the amplification and synthesis circuit 54 is supplied to a bypass filter 61 to extract an FM-modulated luminance signal, and the FM-modulated λ;V degree signal is supplied to a carp degree signal reproduction processing circuit 62 and demodulated. The demodulated luminance signal is extracted through a low-pass filter 63.

Further, the output signal of the amplification/synthesis circuit 54 is supplied to a low-pass filter 64 to extract a low-pass converted carrier color signal of the PAL signal or pseudo-PAL signal, and the low-pass converted carrier color signal is sent to the ACC circuit 64. and is automatically gain controlled based on the berth 1 signal. in this case,
When the signal to be reproduced is pseudo PΔL-3, since the enhancement of the perspective word is suppressed during recording as described above, the carrier color signal is enhanced.

This system? The low frequency converted carrier color signal is supplied to a frequency conversion circuit 66 and converted to the original frequency. That is, the frequency from the crystal oscillation circuit 71 is the subcarrier frequency of the PAL signal, f S = 4.43 MHz. $
A carrier wave XO is obtained, which is supplied to the frequency conversion circuit 72, and a carrier wave whose frequency is set to [c=688kHz as described later is obtained from the voltage controlled oscillation circuit 73,
By supplying this to the frequency conversion circuit 72, a carrier wave for frequency conversion with a frequency of f s + f c = 5.12 MHz is obtained from the frequency conversion circuit 72 through the bypass filter 74, and this carrier wave for frequency conversion is subjected to phase control. The reproduced carrier color signal is supplied to a circuit 75 and subjected to phase control in order to eliminate crosstalk from adjacent tracks, and the controlled carrier wave for frequency conversion is supplied to a frequency conversion circuit 66 to provide a low frequency converted carrier. The color signal is converted back to its original frequency. The carrier color signal converted to the original frequency is extracted through a bandpass filter 67 and further through a comb filter 68 for removing the wolf talk from the adjacent trunk.

Here, the carrier color signal of the original frequency obtained from the comb filter 68 is supplied to a burst gate circuit 76 to extract a burst signal, and the extracted burst signal is supplied to a phase comparator circuit 77 to generate a crystal oscillation. The phase is compared with the reference carrier wave XO obtained from the circuit 71, and the PC error voltage to the output of the phase comparison circuit 77 is sent to the voltage controlled oscillation circuit 7.
3, the voltage side '41' controls the oscillation frequency of the oscillation circuit 73.

From the luminance signal and carrier color signal obtained in the above manner in the reproduction system, a PAL signal or pseudo PAL signal,
A video output of a SECAM signal and red, green, and blue primary color signals is obtained.

That is, the carrier color signal obtained from the comb filter 68 of the reproduction system is supplied to the signal selection processing circuit 81. Further, the luminance signal obtained from the low-pass filter 63 is supplied to the horizontal synchronization signal bone 1Ti11 circuit 78 to extract the horizontal JIJI signal, and the horizontal synchronization signal is sent to the PLL frequency dividing circuit 79.
A signal HH which is inverted for each line is obtained, and this signal HH is supplied to the signal selection processing circuit 81.

Furthermore, detection times! From 91, rotating magnetic heads 52 and 5
3 is a detection signal J indicating a transition from one track to an adjacent track when crossing the track diagonally as described above.
D is obtained, and this detection signal JD is sent to the signal selection processing circuit 81.
supplied to

Specifically, the detection circuit 91 is a burst gate circuit 76.
The burst signal obtained from the crystal oscillation circuit 71 is supplied to the phase comparator circuit 92, the carrier wave Xo obtained from the crystal oscillation circuit 71 is supplied to the terminal O of the switch 93, and the phase of the lIa transmitted wave XO is inverted by the inverter 94. The output carrier wave XI is supplied to the terminal I of the switch 93, and the output signal HH of the above-mentioned PLL frequency dividing circuit 79 is supplied to the switch 93 as a switching control signal. 0 side and the carrier wave XO is taken out from the switch 93. At the same time, on the line where the signal 1-IH is at a low level, the switch 93 is switched to the terminal ■ side and the carrier wave x■ is taken out from the switch 93. 93, carrier waves X and J whose phase is inverted every line are obtained, and this carrier wave
J is supplied to the phase comparison circuit 92, and the phase comparison circuit 92
The burst signal obtained from the pulse 1-gate circuit 76 is compared in phase with the carrier wave XJ of the output of the switch 93, and the output voltage of the phase comparison circuit 92 is taken out as the detection signal JD.

Therefore, as is clear from FIG. 6, when the rotating magnetic head diagonally crosses the trunk as shown by arrow 5 in FIG. 5, the detection signal JD remains on the same track. The detection signal JD maintains a positive or negative value and inverts from positive to negative or from negative to positive when the rotating magnetic head moves from one track to an adjacent trunk.

Although not shown, the signal selection processing circuit 8I includes a delay circuit that delays the input carrier color signal by one line, and selectively switches and extracts the input carrier color signal and the carrier color signal delayed by one line. a switch; an addition circuit for adding the input carrier color signal and the carrier color signal delayed by one line; and a subtraction circuit for subtracting the carrier color signal delayed by one line from the input carrier color signal; It has a switch that selectively switches and takes out the signal of the output of the subtracting circuit and the signal whose phase is inverted with respect to the signal, and the signal H)T which is inverted for each line of the output of the PLL frequency dividing circuit 79 and the detection circuit 9
The above-mentioned detection signal JD obtained from 1 is supplied to the signal selection processing circuit 81, and the above-mentioned switches are switched and controlled based on the signal HH to the detection signal JD.
The output terminal 82 receives a carrier color signal JG in which the line sequential aspect of the PAL signal or pseudo PAL signal is corrected to a normal one.
is taken out, and an AM-modulated blue color difference signal BY and an AM-modulated red color difference signal RY, which are synchronized PAL signals or pseudo-PAL signals, are taken out at output terminals 83 and 84.

That is, if the input carrier color signal is TH and the time-delayed carrier color signal of one line is DL, the rotating magnetic heads 52 and 53 diagonally traverse the tracks from one track to the next as described above. When moving to the track, the input carrier color signal TH and delayed carrier color signal DL are
When a PAL signal is reproduced, it becomes as shown in the upper part of FIG. 7, and when a pseudo PAL signal is reproduced, it becomes as shown in the lower part of FIG. The carrier color signal JG obtained at the output terminal 82 is obtained by extracting the input carrier color signal TH when the detection signal JD is positive, and extracting the delayed carrier color signal DL when the detection signal JD is negative. Therefore, when a PAL signal is reproduced, as shown in the upper part of FIG. 7, and when a pseudo PAL signal is reproduced, as shown in the lower part of FIG. 7, there is a rotating magnetic head. Although the line immediately after transitioning from a track to an adjacent track does not have a normal phase, the line sequential mode has been corrected to a normal one. Further, when a PAL signal is reproduced, the AM-modulated blue color difference signal BY obtained at the output terminal 83 is the input carrier color (IT number T H
and the delayed conveyance color signal DL are added and averaged. Therefore, as shown in the upper part of FIG. It has only the AM modulated blue color difference signal component, and when a pseudo PAL signal is reproduced, the signal HI-1 is at a high level and the detection signal JD
is positive, or when the signal HH is at a low level and the detection signal JD is negative, the input carrier color signal TH is taken out; otherwise, the delayed one-pass color signal DL is taken out; As shown in the lower part of FIG. 7, each line except the line immediately after the rotating magnetic head transfers from one trunk to an adjacent trunk has only the component of the AM-modulated blue color difference signal. Furthermore, when a PAL signal is reproduced, the AM-modulated red color difference signal RY obtained at the output terminal 84 is detected when the signal HH is at a high level and the detection signal JD is positive, or when the signal HH is at a low level. When the signal JD is negative, the delayed carrier color signal DL is subtracted from the input carrier color signal TH to extract the averaged result, and in other cases, the delayed carrier color signal DL is subtracted from the input carrier color signal TH. It is obtained by subtracting and averaging the continuous color signal DL, then inverting the phase (subtracting and averaging the manually delivered color signal TH from the delayed color signal DL). As shown in the upper part of Figure 7, each line except the line immediately after the rotating magnetic head transitions from one track to the adjacent track has only the component of the AM-modulated red color difference signal, which is a pseudo-PAL signal. When the signal is regenerated, the signal HH is at a high level and the detection signal J
When D is positive or signal HH is low level, detection signal JD
When is negative, the delayed carrier color signal DL is extracted; otherwise, the input carrier color signal TH is extracted. Therefore, as shown in the lower part of FIG. Each line, except for the line immediately after transferring to the adjacent trunk, contains only the AM-modulated red color difference signal component.

The carrier color signal JG obtained at the output terminal 82 and whose line sequential form has been corrected to a normal one is supplied to the burst replacement circuit 85, and the signal HH output from the PLL frequency dividing circuit 79 is supplied to the burst replacement circuit 85.
The detection signal JD obtained from the detection circuit 91 and the reference carrier wave XO of f s =4.43 MHz obtained from the ice crystal oscillation circuit 71 are supplied to the burst replacement circuit 85. The burst signals, including those on lines that do not have the above-mentioned regular phase, are replaced with the desired ones, and the low-pass filter 63 of the carrier color signal and reproduction system in which this burst signal is replaced.
The luminance signals obtained from the PAL signal are supplied to the combining circuit 86 and combined, and a PAL signal or a pseudo PAL signal is derived from the output terminal 95. Furthermore, the synchronized AM-modulated blue color difference signals BY and A obtained at the output terminals 83 and 84 are
The M-modulated red color difference signal RY is supplied to the color demodulation circuit 87, and the signal HH output from the PLL frequency dividing circuit 79, the detection signal JD obtained from the detection circuit 91, and the crystal oscillation circuit 71
The group t of f S =4.43M I-I z obtained from
The $ carrier wave xO is supplied to the color demodulation circuit 87, where the blue color difference signal and the red color difference signal are respectively demodulated by synchronous detection, and the demodulated baseband blue color difference signals B-Y and The red color difference signal R-Y and the luminance signal obtained from the low-pass filter 63 are supplied to the SECAM encoder 88 and encoded, and output to the output terminal 96.
In addition, the baseband blue color difference signal B-Y and red color difference signal R-Y output from the color demodulation circuit 87 and the luminance signal obtained from the low-pass filter 63 are outputted to the matrix circuit 89. 71-, and a red signal to output terminal 97.98.99.

Green and blue primary color signals R, G, and B are derived.

Effects of the Invention According to the present invention, the luminance signal of the PAL signal is FM modulated,
Hearth 1 - Intensifies the signal and converts the carrier color signal including the burst signal to a lower frequency using a frequency converting carrier formed on the basis of a base carrier whose frequency obtained from the oscillation circuit is equal to the subcarrier frequency of the PAL signal. A SECAM/pseudo-PAL conversion circuit is provided on the input side of the recording system, and when the signal to be recorded is a PAL signal, the PAL signal is supplied as is to the recording system, and the signal to be recorded is SECA.
When it is an M signal, the SECAM/pseudo-PAL conversion circuit supplies a pseudo-P edge signal subtracted by 1 from the SECAM signal to the recording system, and also converts the SECAM/pseudo-PAL
The reference carrier wave obtained from the above-mentioned oscillation circuit of the recording system is used as the subcarrier wave that is AM-modulated with the line-sequential blue and red color difference signals demodulated in the conversion circuit, and the PAL signal reproduced from the magnetic tape or The FM-modulated luminance signal of the pseudo PAL signal is demodulated, the carrier color signal is automatically gain controlled based on the burst signal, and the frequency at which the carrier color signal including the burst signal is obtained from the oscillation circuit is the subcarrier frequency of the PAL signal. On the output side of the reproduction system, which converts the frequency to the original frequency using a frequency conversion carrier wave formed based on a reference carrier wave equal to A signal selection processing circuit obtains synchronized AM modulated blue and red color difference signals from the signal, and demodulates the AM modulated blue and red color difference signals output from the signal selection processing circuit by synchronous detection, respectively. A color demodulation circuit that obtains baseband blue and red color difference signals is provided, and the base IC transmission wave obtained from the above oscillation circuit of the reproduction system is used for synchronous detection of the blue and red color difference signals in the color demodulation circuit. A special oscillation circuit that generates a subcarrier that is AM-modulated with line-sequential blue and red color difference signals that are demodulated during conversion from SECAM signals to pseudo-PAL signals during recording; Also, there is no need for a special oscillation circuit that generates a subcarrier for demodulating the synchronized AM-modulated blue and red color difference signals during reproduction by the same 1υ1 detection, and the configuration is significantly simplified. . In addition, when the recording system is supplied with a pseudo PAL signal obtained from a SECAM/pseudo PAL conversion circuit, the burst signal in the recording system is enhanced by PA
Since it is suppressed compared to when the L signal is supplied, SECA
The M signal is converted to a pseudo PAL signal and recorded/played.
Decrease in color saturation when displayed on an AL television receiver is suppressed.

[Brief Description of the Drawings] Fig. 1 is a connection diagram showing an example of the input system and recording system of the video tape recorder of the present invention, and Fig. 2 shows an example of the playback system and output system of the video tape recorder of the invention. The connection diagrams and FIGS. 3 to 7 are diagrams for explaining the operation.

Claims (1)

[Claims] The SECAM signal is demodulated into its FM-modulated line-sequential blue and red color difference signals, and the demodulated line-sequential blue and red color difference signals have a frequency equal to the subcarrier frequency of the PAL signal and a phase of blue and red. Subcarriers different by 90 degrees are AM-modulated with a red color difference signal, and the frequency is equal to the subcarrier frequency of the PAL signal and the phase is blue and red color difference signals for the AM modulated line sequential blue and red color difference signals. A SECAM/pseudo PAL conversion circuit adds different burst signals to the pseudo PAL signal and converts it into a pseudo PAL signal, and FM modulates the luminance signal of the PAL signal or the pseudo PAL signal obtained from the above SECAM/pseudo PAL conversion circuit, and converts the burst signal into a pseudo PAL signal. A recording system that converts a carrier color signal including a burst signal to a lower frequency using a frequency converting carrier wave formed based on a reference carrier wave whose frequency obtained from an oscillation circuit is equal to the subcarrier frequency of a PAL signal, and a magnetic tape. demodulates the FM-modulated luminance signal of the PAL signal or pseudo-PAL signal reproduced from the PAL signal, performs automatic gain control of the carrier color signal based on the burst signal, and adjusts the carrier color signal including the burst signal to the frequency obtained from the oscillation circuit. is PA
A reproduction system converts the frequency to the original frequency using a frequency conversion carrier wave formed based on a reference carrier wave equal to the subcarrier frequency of the L signal, and a carrier color signal output from this reproduction system, which is delayed by one line. a signal selection processing circuit that obtains synchronized AM-modulated blue and red color difference signals from the carrier color signals; a color demodulation circuit that demodulates and obtains baseband blue and red color difference signals;
A reference carrier wave obtained from the oscillation circuit of the recording system is used as a subcarrier wave to be modulated, and the enhancement of the burst signal in the recording system causes the SECAM wave to be modulated in the recording system.
/ When the pseudo PAL signal obtained from the pseudo PAL conversion circuit is supplied, it is suppressed compared to when the PAL signal is supplied, and the reference carrier obtained from the oscillation circuit of the reproduction system is blue in the color demodulation circuit. and a videotape recorder used as a subcarrier for synchronous detection of red color difference signals.