JPH046319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color signal recording device and method for recording NTSC and PAL color video signals with high density.

In order to perform high-density recording, household magnetic recording and reproducing devices (VTRs) do not have guard bands2.
A head helical scan method is used. This method utilizes the azimuth loss of the head in order to eliminate crosstalk components from adjacent video tracks during playback that occur due to the absence of a guard band. However, for color signals whose center frequency is band-converted to a low frequency of 1 MHz or less and recorded, removal of crosstalk components using the azimuth loss of the head cannot be expected. For this reason, crosstalk components with respect to color signals during reproduction are generally removed by utilizing the vertical correlation of video signals.

Furthermore, when a color signal is converted to a low frequency and recorded, the second-order distortion component of the low frequency color signal becomes a bead disturbance during reproduction, resulting in deterioration of image quality.

As described above, there are existing techniques in the prior art for removing crosstalk components of color signals and visually reducing bead interference caused by secondary distortion components of low-frequency color signals.

For example, when explaining the VHS system,
NTSC color signal uses 4-phase PS (Phase Shift)
The color signal is divided into one horizontal period (hereinafter referred to as 1H).
), the phase is shifted by 90 degrees for each field, and the direction of the phase shift is reversed for each field.
The PAL system uses a single-field 4PS system for color signals, in which only the color signal of one field is phase-shifted by 90 degrees every 1H, and the other field is recorded without any phase shift.

Similarly, to explain the β method, the color signal of the NTSC method uses one-field PI (Phase Invert).
method is used, and only the color signal of one field is used.
The phase is reversed every 1H, and the other field is recorded without phase shift. A frequency interleave method is used for PAL color signals, and 1/1/2 of the horizontal frequency (hereinafter referred to as _fH ) is used as the low-range color signal during recording.
An offset corresponding to 4 is provided between the fields.

However, with these conventional technologies, as mentioned above,
Because the color signal processing methods for the NTSC and PAL systems are different, dedicated circuits (especially IC circuits) are required for each.
This is problematic in terms of performance and cost.

An object of the present invention is to eliminate the drawbacks of the prior art as described above, to achieve a common color signal processing circuit in NTSC and PAL VTRs, and to provide a color signal recording system suitable for IC implementation that is effective in reducing costs through this commonality. The goal is to provide equipment.

In order to achieve the above object, the present invention includes a reference oscillator that oscillates at a specific oscillation frequency, and a low-frequency conversion carrier that generates a low-frequency conversion carrier whose phase changes at a predetermined frequency from the oscillation signal from the reference oscillator. a mixer for generating a low-pass converted carrier color signal by mixing the low-pass converted carrier from the low-pass converted carrier generator and a carrier color signal to be recorded; and a mixer for generating a low-pass converted carrier color signal; For the NTSC system, the ratio of the frequency of the low frequency conversion carrier color signal to the horizontal frequency is multiplied by 8.
It is slightly different from the case of the PAL method, and the value multiplied by 8 above is expressed as the product of prime numbers in either method, and it is assumed that there is a common prime number among the prime numbers of 3, 5, or 7. The frequency of the low-pass conversion carrier color signal of both of the above-mentioned methods is selected, and the low-pass conversion carrier generator includes a frequency divider with a frequency division ratio according to the common prime number, and this frequency divider is operated in either system, and many circuits can be used in both systems.

FIG. 1 shows an embodiment of a color signal processing circuit using the present invention.

In Fig. 1, 1 is a recording color signal input terminal, 2 is a recording color signal input terminal;
is the reproduced color signal input terminal, 3 is the first changeover switch, 4 is the ACC circuit (automatic color signal control circuit), 5 is the first converter (frequency converter), and 6 is the first
LPF (low pass filter), 7 is the first killer circuit, 8 is the recording color signal output terminal, 9 is the first
BPF (band pass filter), 10 is a comb filter, 11 is a second killer circuit, 12 is a reproduction color signal output terminal, 13 is a second changeover switch, 14 is a phase detector, 15 is a second LPF, 16 is the third changeover switch, 17 is the first VCO, 18 is the 90 degree phase shifter, 19 is the killer detector, and 20 is the third
LPF, 21 is burst gate pulse input terminal,
22 is a second converter, 23 is a second BPF,
24 is a horizontal synchronizing pulse input terminal, 25 is a control voltage generation circuit, 26 is a second VCO, 27 is a head switching pulse input terminal, 28 is a frequency division f _H output terminal, 29
is a VCO output signal input terminal, 30 is a phase correction signal input terminal, 31 is a phase shift signal output terminal, 32, 3
3 is a frequency dividing circuit, and 34 is a phase selection circuit.

During recording, there are three selector switches 3, 13, and 16.
is connected to the position shown in the figure, and the color signal of the carrier frequency f _SC from the input terminal 1 is guided to the ACC circuit 4. This color signal is level-controlled by the ACC circuit 4, and the first
converter 5 and second changeover switch 13. The color signal guided to the first converter 5 is frequency-converted by the carrier signal from the second BPF 23, and the low-frequency converted color signal is extracted as the output of the first LPF 6. This low-range color signal passes through the first killer circuit 7 and is output from the output terminal 8. On the other hand, the color signal guided to the second changeover switch 13 is transmitted to the phase detector 14 and the killer detector 19.
guided by. The phase detector 14 performs phase detection of the burst signal, and the phase detector 14 and the second
PLL composed of LPF15 and first VCO17
(Phase Locked Loop)
The oscillation frequency of VCO 17 is made stable.
The killer detector 19 detects the burst signal to determine whether it is color or black and white, and this determination signal is passed through the third LPF 20 and guided to the first and second killer circuits 7 and 11, and outputs the killer circuit when black and white, respectively. cut. On the other hand, in the AFC circuit composed of the control voltage generation circuit 25, the second VCO 26, the frequency division circuits 32 and 33, and the phase selection circuit 34, the control voltage generation circuit 25, the second VCO 26, and the frequency division circuit 3
3, the second VCO2
A stable frequency signal is introduced to the output of 6. The output signal of the second VCO 26 passes through a frequency dividing circuit 32 and a phase selection circuit 34, and a signal S _L whose center frequency is equal to the carrier frequency of the low-range color signal is guided to the second converter 22. In the second converter 22,
Output signal S _L from AFC circuit and first VCO circuit 1
7 output signal S _S is performed, and the second
A carrier signal (S _S tS _L ) having the sum frequency of both signals is extracted from the output of the BDF 23 , and the carrier signal is guided to the first converter 5 . Therefore, a stable low-frequency color signal whose carrier frequency is phase-locked to the output signal of the AFC circuit is obtained at the output terminal 8.

During playback, there are three selector switches 3, 13, and 16.
is connected in a position opposite to that shown in the figure, and the low frequency color signal from the input terminal 2 is guided to the first converter 5 through the ACC circuit 4. This first converter 5
The low-range color signal guided by the second
The frequency is converted by the carrier signal from BPF 23, and the carrier frequency is _sent to the output of the first BPF 9.
color signals are obtained. Next stage comb filter 10
The color signal from which crosstalk components from adjacent video tracks have been removed is sent to the second killer circuit 1.
1 to the output terminal 12. On the other hand, a color signal having a carrier frequency f _SC is guided to the phase detector 14 and the killer detector 19 . In the phase detector 14, the first
Phase detection is performed between the output signal from the VCO having a center frequency of f _SC and the burst signal, and the detected output is guided to the control voltage generation circuit 25 to control the above-mentioned AFC circuit. The killer detector performs the same operation as during recording. On the other hand, the AFC circuit operates almost the same as during recording, and the above phase detection output is controlled by the second VCO 26 through the control voltage generation circuit 33.
Since the signal is fed back to the first converter 5, a reproduced color signal with a stable carrier frequency f _SC is obtained at the output terminal 12.

The present invention particularly relates to the portion of the AFC circuit in the example of the color signal processing circuit shown in FIG.

Figure 2 shows the color signal processing circuit shown in Figure 1.
This is an example in which the present invention is used in an AFC circuit.

In FIG. 2, 35 is an input terminal for a control voltage that switches between the NTSC system and PAL system, 36 is an input terminal for a horizontal synchronizing pulse or an equivalent signal,
37 is a first frequency dividing circuit composed of a 1/2 frequency dividing circuit 38 and a 1/4 frequency dividing circuit 39, 40 is a second frequency dividing circuit, and 41 is a third frequency dividing circuit whose frequency dividing ratio can be changed. Frequency dividing circuits 42 and 43 each have a different frequency dividing ratio;
44 is a changeover switch. In FIG. 2, the phase selection circuit 34 includes a phase correction circuit, and when the carrier wave of the color signal during reproduction is inverted, the phase correction signal from the input terminal 30 causes a phase shift signal to be output from the output terminal 31. is inverted.

In the present invention, as shown in FIG. 2, the above AFC circuit is composed of a 1/2 frequency divider circuit 38 and a 1/4 frequency divider circuit 39 which receives the output of the 1/2 frequency divider circuit 38 as an input signal. A first frequency dividing circuit 37, a second frequency dividing circuit 40 whose frequency division ratio is at least 1/3, 1/5, or 1/7, and switching the frequency division ratio between the NTSC system and the PAL system. The third frequency dividing circuit 41 is characterized in that it includes a third frequency dividing circuit 41.

In FIG. 2, as described above, the control voltage generating circuit 25, the second VCO 26, and the second and third frequency dividing circuits 40 and 41 constitute a PLL circuit. Therefore, by switching the frequency division ratio of the third frequency dividing circuit 41 between the NTSC system and the PAL system, the second
Signals with different frequencies can be obtained from the output of the VCO 26 using each method. This second VCO2
The output signal of 6 is counted down to 1/8 by the first frequency dividing circuit, and then the output signal of
By guiding the carrier signal of the sum frequency from the second converter 2 to the first converter 5, the carrier wave frequency of the low frequency color signal during recording is changed to NTSC.
You can switch between PAL and PAL formats. In other words, the carrier frequency of both types of low-pass color signals can be arbitrarily selected.

Furthermore, by making the first frequency dividing circuit 37 a 1/8 frequency dividing circuit, a 1/8 offset (corresponding to 1/8 f in frequency and 45 degrees in _H phase) is applied to the carrier frequency of the low frequency color signal in the PAL system. ) can be made.

As described above, using the present invention, the NTSC system and
The AFC circuit can also be used in the PAL color signal processing circuit.

In the present invention, in order to make the circuit more suitable for IC implementation, the first frequency dividing circuit 37 is configured with a 1/2 frequency dividing circuit 38 and a 1/4 frequency dividing circuit 39, and the second frequency dividing circuit 37 is configured with a 1/2 frequency dividing circuit 38 and a 1/4 frequency dividing circuit 39,
By replacing the high-speed frequency divider circuit that counts down the output signal of the VCO 26 with one 1/2 frequency divider circuit 38, the number of high-speed drive frequency divider circuits can be reduced, making it possible to
This makes it suitable for IC implementation. Similarly, in order to reduce the number of frequency dividing circuits driven at high speed, by selecting the frequency division ratio 1/m of the second frequency dividing circuit 40 to be 1/3, 1/5, or 1/7, The number of frequency dividing circuits driven at high speed by the second frequency dividing circuit 40 can be reduced to four or less.

Next, a specific example in which the present invention is applied to color signal processing of PAL and NTSC VTRs will be described.

FIG. 3 shows an example of an AFC circuit in a color signal processing circuit using the present invention.

In FIG. 3, 40 is a frequency division ratio of 1/m (where m is either 3, 5, or 7), 45 to 47 are frequency dividing circuits constituting the third frequency dividing circuit 41,
And each frequency division ratio is 1/l (l is an integer),
ml/8n+1, ml/2(4k+1) (k is an integer). 48 to 50 are D-type flip-flops (hereinafter referred to as FF), and 51 to 54 are output terminals for phase-shifted signals whose phases differ by 90 degrees, respectively. In the figure, an example of a configuration different from that in FIG. 2 is shown as the third frequency dividing circuit 41.

First, a case will be described in which the embodiment shown in FIG. 3 is used in a PAL system VTR.

In the PAL system, the changeover switch 44 is connected as shown, and the center frequency of the output signal of the second VCO 26 is (8n+1) _fH . By guiding this output signal to the first frequency dividing circuit 37, the FF 48
The Q output of is a signal with a center frequency of 1/2 (8n + 1) f _H , and the output of the 1/4 divider circuit made up of FF49 and 50 is a signal with a center frequency of (n + 1/8) f _H. is derived, and four phase-shifted signals having a center frequency of (n+1/8)f _H and phases different by 90 degrees are obtained at output terminals 51 to 54, respectively. This phase-shifted signal is guided through the phase selection circuit 34 to the second converter 22 shown in FIG. ) f _H , resulting in a signal with a 1/8 offset. This 1/8 offset gives a 1/4 line offset to the second-order distortion component of the low-range color signal during reproduction, and it is possible to visually reduce the beat disturbance caused by this second-order distortion component.

As a means to remove crosstalk components of color signals from adjacent video tracks, for example, the above low-frequency color signal may be phase-shifted by 90 degrees every 1H in one field, and left as is without phase shift in the other field. There is a way to record it. In this case, for example, the low-range color signal of video track A that records a field delayed by 90 degrees every 1H has a center frequency, assuming that the low-range color signal carrier frequency f _L is
f _L −f _H /4, resulting in a spectrum with f _H /2 intervals. In addition, the center frequency of the low-frequency color signal of video track B, which recorded the field without phase shift, is
It becomes a spectrum with f _H /2 intervals at f _L. During playback, the low frequency color signal of video track A is changed to 90% every 1H.
When the phase is advanced step by step and returned to the original color signal in which the carrier frequency is f _S and the phase is continuous, this color signal becomes a spectrum with a center frequency of f _S and an interval of f _H /2, and the video track B The crosstalk component from the signal has a spectrum with a center frequency of f _S +f _H /4 and an interval of f _H /2. Also, if the low-frequency color signal of video track B is restored to the original frequency color signal, this color signal becomes a spectrum with a center frequency of f _S and an interval of f _H /2, and the crosstalk component from video track A is The center frequency is f _S +f _H /4 and the spectrum is spaced at f _H /2 intervals. In this way, the color signal from the main track and the crosstalk component are
Since f _H /4 interleaving is performed, crosstalk components can be removed by a comb filter using a 2H delay line. This crosstalk component removal effect is the same even when the phase shift direction is advanced by 90 degrees.

Next, a case will be described in which the embodiment shown in FIG. 3 is used in an NTSC system VTR.

In the NTSC system, the changeover switch 44 is connected in the opposite way to that shown in the figure, and the center frequency of the output signal of the second VCO 26 is 2(4n+1) _fH . This output signal is counted down to 1/8 by the first frequency dividing circuit 37, and phase-shifted signals whose center frequency is (n+1/4) f _H and whose phases differ by 90 degrees are obtained at terminals 51 to 54. It will be done. Therefore, in the same way as described above, the carrier frequency of the low-range color signal during recording is (n+1/4) _fH , which has a 1/4 offset. This 1/4 offset gives a 1/2 line offset to the second-order distortion component of the low-range color signal during playback, making it possible to visually reduce beat interference as in the PAL system.

As a means for removing crosstalk components of color signals from adjacent video tracks, for example, there is a method in which the above-mentioned low-range color signal is reversed in phase every 1H in one field, and recorded as is in the other field. In this case, for example, the low frequency color signal of video track A, which records fields whose phases are reversed every 1H, has a spectrum with a center frequency of f _L -f _H /2 and an interval of f _H . Furthermore, the low-frequency color signal of video track B recorded as is without reverse phase has a spectrum with a center frequency of f _L and an interval of f _H . During playback, when the carrier wave frequency is returned to the original color signal _{with fS} , the color signals from each main video track become a spectrum with center frequency _fS and intervals of _fH , and the crosstalk components from adjacent video tracks are centered. The frequency is f _S +f _H /2, resulting in a spectrum with f _H intervals. In other words, the main color signal and crosstalk component are
Since f _H /2 interleaving is performed, crosstalk components can be removed by a comb filter using a 1H delay line.

In FIG. 3, the frequency division ratio of the frequency divider circuit 46 is
ml/8n-1 may be selected, and the low range color signal in the PAL system is offset by 1/8, and the same effect as described above can be obtained. In addition, the frequency division ratio of the frequency dividing circuit 47 is
You may choose ml/2 (4n-1).

As described above, in the embodiment shown in FIG. 3 using the present invention, color signal processing for each method can be performed by simply switching the frequency division ratio of the third frequency dividing circuit between the NTSC method and the PAL method. I can do it.

FIG. 4 shows an embodiment of the phase selection circuit 34 suitable for the AFC circuit of FIG. 3.

In FIG. 4, 55 is an input terminal for the output signal of the second VCO 26, 56 to 60 are FFs, and 61 to 72
is a NAND gate, 73 is an AND gate, 74~7
7 is an inverter. Phase-shifted signals from the first circuit 37 whose phases differ by 90 degrees are led to the input terminals 51 to 54, and these four phase-shifted signals are
The signal is selected by a multiplexer circuit composed of FFs 4 to 68, and guided to the output terminal 31 through a latch circuit composed of FFs 56 and a phase correction circuit composed of NAND gates 16 to 63 and FFs 57. Here, the latch circuit of FF56 is used to synchronize the timing of the 90 degree phase shift every 1H during recording and playback, and both are connected to the second VCO.
It is phase-locked to the output signal of 26. Further, the above phase correction circuit detects the phase inversion of the carrier wave of the reproduced color signal with the killer detector 19 shown in FIG. Q and Q, the phase of the multi-phase signal input from the output terminal 31 to the second converter 22 shown in FIG. 1 is inverted, and the carrier wave of the reproduced color signal is corrected. FF58~
60 and NAND gates 69-72 and AND gate 7
3 and inverters 74 to 77 are circuits for generating select signals input to the multiplexer circuit.

FIG. 5 shows a time chart showing the operation of this select signal generation circuit.

5a is a horizontal synchronizing pulse or an equivalent signal from the terminal 36, 5b is a head switching pulse from the terminal 27, and 5c and 5h are NTSC/PAL system switching signals from the terminal 35. Become. 5d, 5i are FF60, 5e,
5j is FF59's Q, 5f and 5k are FF58's Q
5g and 5l are the outputs of the AND gate 73. When using PAL system, AND with FF58-60
Select signals from gate 73 are 5d to 5g, respectively.
Terminal 5 is applied only when one field is used.
Phase shift signals 1 to 54 are sequentially selected every 1H.
FF58-60 and AND gate 7 when using NTSC system
The select signals from 3 are as shown in 5i to 5l, respectively, and terminals 52 and 54 are used only when one field is selected.
Phase-shifted signals whose phases differ by 180 degrees are switched and selected every 1H.

FIG. 6 shows a specific embodiment of the second and third frequency dividing circuits in FIG. 3.

In Figure 6, 78-90 are FF, 91-9
7 is a NAND gate, 98 is an AND gate, 99,
100 is an inverter. In one embodiment of FIG. 6, the frequency division ratio of the second frequency dividing circuit 40 is set to 1/3, and the third
The frequency division ratio of the frequency divider circuit 41 is 1/117 in the PAL system.
In contrast, the NTSC format is set to 1/126. In this case, the oscillation frequency of the second VCO 26 is 351f _H for the PAL system and 378f _H for the NTSC system, and the carrier wave frequencies of the low-range color signal are (44-1/8) f _H and (47 + 1/4) f H, respectively. A frequency with _H and 1/8 and 1/4 offsets is selected.

In Figure 6, for example, the value of m in Figure 3 is 3.
The FF is driven at high speed by the second frequency dividing circuit 40.
The number is two, which is the minimum number in the present invention.
Furthermore, the third frequency divider circuit 41 is designed to be a frequency divider circuit that counts down to 1/9 in both the PAL system and the NTSC system.
1/3 frequency divider circuit composed of FF80, 81 and FF8
This is done using a 1/3 frequency divider circuit consisting of 2.83 frequency dividers to reduce the number of FFs that constitute the frequency divider circuit. The frequency of the Q output of the FF82 counted down by 1/9 is 13f _H in the PAL system and 14f _H in the NTSC system. A frequency dividing circuit composed of seven FFs 84 to 90 in the next stage switches the frequency dividing ratio according to each method. For example, in the PAL system, the input signal from terminal 35 is "Low", and the AND of the Q outputs of FF89 and 90
is fed back to the D input of the FF84, so the frequency division ratio is 1/13. In addition, in the NTSC system, terminal 35
The input signal from FF90 becomes “High” and the Q of FF90
Since the output is fed back to the D input of FF84, the frequency division ratio is 1/14. In this way, the counted down signal having the frequency f _H is led to the terminal 28 .

As described above, in the embodiment shown in FIG. 6, it is possible to easily switch the frequency division ratio of the third frequency divider circuit 41 in each method, and by using the frequency divider circuit in both methods, the frequency division ratio can be easily changed. Configure the circuit
The FF has been reduced, making the circuit more suitable for IC implementation.

FIG. 7 shows an embodiment of a third frequency divider circuit in which the frequency division ratio of the third frequency divider circuit 41 of the AFC circuit according to the present invention shown in FIG. 3 is made different.

In FIG. 7, the third frequency divider circuit is the same as that in FIG. 3 in the case of the PAL system, and the frequency division ratio of the frequency divider circuit 101 is different from that of the frequency divider circuit 47 in FIG. 3 in the case of the NTSC system. Therefore, since the PAL method is the same as the embodiment in Fig. 3, we will not particularly explain it here.
The case of NTSC system will be explained.

In this embodiment, the third frequency divider circuit in the NTSC system is composed of a frequency divider circuit 45 with a frequency division ratio of 1/l and a frequency divider circuit 101 with a frequency division ratio of ml/8k. The frequency division ratio by the frequency dividing circuit is 1/8k.
Therefore, the oscillation frequency of the second VCO26 is (8k)
f _H , and this signal is divided into 1/8 by the first frequency dividing circuit 37.
The frequency of the counted down signal is k·f _H. Therefore, as described above, the carrier wave frequency of the low-range color signal during recording is k·f _H , and there is no 1/4 offset. Therefore, when recording, low-range color signals are
By shifting the phase by 90 degrees every 1H, the phase of the second-order distortion component of the low-range color signal during reproduction is reversed every 1A period. In other words, this second-order distortion component is 1/
It has a 2-line offset and can visually reduce beat interference.

Further, as a means for removing crosstalk components of color signals from adjacent video tracks, there is a method in which the direction of the 90 degree phase shift is reversed for each field and recorded. In this case, for example, the low frequency color signal of video track A, which records a field whose phase advances by 90 degrees every 1H, has a center frequency of f _L + f _H /4 and f _H
It becomes a spectrum of intervals. In addition, the low frequency color signal of video track B, which recorded fields delayed by 90 degrees every 1H, has a center frequency of f _L - f _H /4 and f _H
It becomes a spectrum of intervals. When the original color signal with a carrier frequency of f _S is restored during playback, each main color signal becomes a spectrum with a center frequency of f _S and an interval of f _H , and the crosstalk component from video track B to A has a center frequency of f S. becomes a spectrum with f _H intervals at f _S + f _H /2, and the crosstalk component from video track A to B has a center frequency of f _H at f _S - f _H /2.
It becomes a spectrum of intervals. In this way, since the main color signal and the crosstalk component are each interleaved by f _H /2, the crosstalk component can be removed in the same manner as described above.

Figure 8 uses the third frequency divider circuit in Figure 7.
An example of a phase selection circuit 34 suitable for an AFC circuit is shown.

In FIG. 8, 101 to 109 are NAND gates, 110 is an AND gate, and 111 to 113 are inverters. This phase selection circuit 3 in Fig. 8
4 performs almost the same operation as the example shown in FIG. The difference is the circuit that generates the select signal to the multiplexer circuit. In PAL system, terminal 35 is “Low”
FF58, which is a cyclic shift register.
The Q output of ~60 and the output of AND gate 73 are equal to 5d~5g of the time chart shown in FIG. In the NTSC system, terminal 35 is “High”
Then, the head switching pulse of terminal 27 is “Low”
In this case, the output pulse of the shift register composed of the above FF58-60 and AND gate is
The gates 73, FF58, FF59, and FF60 rotate in reverse, and when the head switching pulse is "High", they rotate in the normal direction. This select signal causes terminals 51 to 54 to
The phase-shifted signals are sequentially selected every 1H, and their direction is reversed for each field by the head switching pulse.

This makes it possible to shift the above-mentioned low-range color signal by 90 degrees every 1H.

As a specific example of the values of the second and third frequency dividing circuits shown in FIG. 7, for example, m=3, l=5, n=
43, if k = 45, the oscillation frequency of the second VCO 26 will be 345f _H for the PAL system and 360f _H for the NTSC system.
And the carrier wave frequencies of the low-range color signals are (43+1/8)f _H and 45f _H , respectively. In this way, the low-range color signal of the PAL system has a 1/8 offset, and the NTSC system has no offset.

FIG. 9 shows another embodiment of the third frequency dividing circuit according to the present invention.

In Fig. 9, 114 is a horizontal synchronizing pulse or equivalent input terminal, and 115 is a frequency division ratio.
ml/8P-1 (where P is an integer) frequency dividing circuit, and 116 is a changeover switch. In this case, the frequency dividing circuit 47 in the NTSC system is the same as the example in FIG.
Here, we will specifically explain the PAL system.

In this embodiment, in the PAL system, the frequency division ratio of the third frequency dividing circuit is changed every 1H by the switch 116, so the oscillation frequency of the second VCO 26 is
It switches between (8n+1)f _H and (8P-1)f _H every 1H. In this case, the carrier frequency of the low gamut color signal is (n
+1/8) f _H and (P-1/8) f _H , with a 1/8 offset. Therefore, cross-beat interference caused by second-order distortion components of low-frequency color signals is visually reduced.

In addition, to remove crosstalk components from color signals from adjacent video tracks, the above-mentioned low-range color signals are recorded as they are without phase shifting, and when played back, they are returned to the color signals at the original carrier frequency. The color signal and the crosstalk component are spectrally interleaved by f _H /4. Therefore, crosstalk components can be removed by a comb filter using a 2H delay line.

In this case, the phase selection circuit outputs a signal fixed to one of the outputs of the first frequency dividing circuit 37 in the PAL system, and is similar to the embodiment in FIG.
In the NTSC system, the output of the first frequency divider circuit 37, whose phase is inverted only during one field, may be switched every 1H, and a fixed signal may be output during the other field, as shown in Fig. 4. This can be easily inferred from an example of a phase selection circuit.

In FIG. 9, the frequency division ratio of the frequency dividing circuit 47 is
Even if you select ml/2 (4k-1), you can obtain the same effect as above.

Furthermore, if the frequency dividing ratio of the frequency dividing circuit 47 is selected as ml/8k, the NTSC system in the embodiment shown in FIG. 7 and the PAL system in the above embodiment can be used.
It will be easy to understand that similar effects can be obtained.

FIG. 10 shows another embodiment of the third frequency dividing circuit according to the present invention.

In FIG. 10, the PAL system is the same as the example in FIG. 3, and here, the NTSC system will be particularly explained.

The NTSC system in this embodiment is shown in Figure 9.
It is based on the same idea as the PAL method. The carrier frequencies of the low-range color signals in this case are (k+1/4) f _H and (P-1/4) f _H , both of which have a 1/4 offset. Therefore, the second-order distortion component of the low-range color signal is 1/
There is a two-line offset, and crossbeat interference is visually reduced.

In addition, crosstalk components of color signals from adjacent video tracks are interleaved with the main color signal by f _H /2 during playback without phase shifting the low-frequency color signals, so a comb-shaped filter using a 1H delay line is used. Can be removed.

As described above, in the present invention, the third frequency dividing circuit 41
By changing the configuration of
Various color signal processing for the PAL system becomes possible.

The present invention is not limited to the configuration of the frequency dividing circuit described here, but includes many more configurations.

By using the present invention, NTSC and
The color signal processing circuit compatible with the PAL system can be used in common, and the AFC circuit can have a relatively simple configuration. Furthermore, by reducing the number of frequency dividing circuits, it is possible to reduce the number of elements when integrated into an IC, and to reduce power consumption by reducing the number of FFs that drive at high speed.

Furthermore, by using both the NTSC method and the PAL method as described above, an IC with excellent economic efficiency can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of a color signal processing circuit using the present invention, Fig. 2 is a block diagram showing a circuit configuration of the present invention, and Fig. 3 is a block diagram showing an embodiment of a color signal processing circuit using the present invention.
A block diagram showing an embodiment of the AFC circuit, FIG. 4 is a circuit diagram showing an embodiment of the phase selection circuit used in the AFC circuit of FIG. 3, and FIG. 5 shows the operation of the phase selection circuit of FIG. 4. 6 is a circuit diagram showing an embodiment of the third frequency dividing circuit used in the AFC circuit of FIG. 3, and FIG. 7 is a third frequency dividing circuit forming a part of the present invention. FIG. 8 is a block diagram showing an embodiment of the phase selection circuit used in the AFC circuit including the circuit of FIG. FIG. 10 is a block diagram showing another embodiment of the third frequency dividing circuit forming a part of the present invention. 25; control signal generation circuit, 26; second VCO,
32, 33; Frequency dividing circuit, 34; Phase selection circuit, 3
7; first frequency divider circuit, 38; 1/2 frequency divider circuit, 3
9; 1/4 frequency divider circuit, 40; second frequency divider circuit, 4
1; Third frequency dividing circuit.

Claims (1)

[Claims] 1. A reference oscillator that outputs an oscillation signal at a reference oscillation frequency, a frequency divider that divides the oscillation signal from the reference oscillator to a predetermined frequency, and a frequency-divided signal output from the frequency divider. A phase switch that outputs a phase shift signal in which the phase shifts by a predetermined amount every horizontal period in one field and no phase shift in the other field, and the color of the color signal system to be recorded. a color subcarrier oscillator that oscillates at a frequency approximately equal to the subcarrier frequency; a first mixer that mixes the phase shift signal from the phase switch and the oscillation signal from the color subcarrier oscillator; and mixing from the first mixer. It consists of a second mixer that mixes the output and the carrier color signal to be recorded to generate a low frequency converted carrier color signal, and when the color signal method to be recorded is the NTSC method, the reference oscillation frequency of the reference oscillator. is selected to be an integer multiple of the horizontal frequency, and the multiple of this integer multiple is selected to be a value that causes an excess or deficit of 1/4 when divided by 8, which is a multiple of 3, and the phase change in the phase switch is If the predetermined amount is selected as 180 degrees and the color signal method to be recorded is PAL method,
The reference oscillation frequency of the reference oscillator is selected to be an integer multiple of the horizontal frequency, and the multiple of this integer multiple is a multiple of 3, and is selected to be a value that causes an excess or deficit of 1/8 when divided by 8, and the phase A color signal recording device characterized in that the predetermined amount of phase shift in the switch is selected to be 90 degrees. 2. The color signal recording device according to claim 1, wherein the frequency divider includes a 1/8 frequency dividing circuit. 3 The reference oscillation frequency of the reference oscillator is selected to be 378 times the horizontal frequency when the color signal system to be recorded is the NTSC system, and is selected to be 375 times the horizontal frequency when the color signal system to be recorded is the PAL system. 2. The color signal recording device according to claim 1, wherein the color signal recording device is selected to have a value of . 4. A reference oscillator that outputs an oscillation signal at a reference oscillation frequency, a first frequency divider that divides the oscillation signal from the reference oscillator to a predetermined frequency, and one field from the divided signal output from the frequency divider. A phase switcher that outputs a phase shift signal in which the phase shifts by a predetermined amount every horizontal period, and in the other field, the phase shift does not occur every horizontal period, and a color subcarrier frequency of the color signal system to be recorded. a color subcarrier oscillator that oscillates at approximately equal frequencies; a first mixer that mixes the phase shift signal from the phase switch and the oscillation signal from the color subcarrier oscillator; and a mixed output from the first mixer that is recorded. a second mixer that generates a low-pass converted carrier color signal by mixing the desired carrier color signal; and a second mixer that includes a 1/3 frequency divider and divides the oscillation signal at the reference oscillation frequency to a predetermined frequency. It consists of a frequency divider and a control circuit that controls the reference oscillation frequency of the reference oscillator according to the phase difference between the frequency division signal from the second frequency divider and the comparison signal related to the horizontal synchronization signal. If the signal system is NTSC, the reference oscillation frequency of the reference oscillator is selected as an integer multiple of the horizontal frequency, and this integer multiple is a multiple of 3 and when divided by 8, it has an excess of 1/4 or If the value that causes the shortage is selected, the predetermined amount of phase shift in the phase switch is selected to be 180 degrees, and the color signal system to be recorded is PAL,
The reference oscillation frequency of the reference oscillator is selected to be an integer multiple of the horizontal frequency, and the multiple of this integer multiple is a multiple of 3, and is selected to be a value that causes an excess or deficit of 1/8 when divided by 8, and the phase A color signal recording device characterized in that the predetermined amount of phase shift in the switch is selected to be 90 degrees. 5. The color signal recording device according to claim 4, wherein the first frequency divider includes a 1/8 frequency dividing circuit. 6 The reference oscillation frequency of the reference oscillator is selected to be 378 times the horizontal frequency when the color signal system to be recorded is the NTSC system, and is selected to be 375 times the horizontal frequency when the color signal system to be recorded is the PAL system. 5. The color signal recording device according to claim 4, wherein the color signal recording device is selected to have a value of . 7. The color signal recording device according to claim 4, wherein the 1/3 frequency divider is provided at the first stage of the second frequency divider. 8. A reference oscillator that oscillates at a specific oscillation frequency,
A low-frequency conversion carrier generator that generates a low-frequency conversion carrier whose phase changes at a predetermined frequency from the oscillation signal from the reference oscillator, and a low-frequency conversion carrier from the above-mentioned low-frequency conversion carrier generator should be recorded. It consists of a mixer that generates a low-frequency converted carrier color signal by mixing the low-frequency converted carrier color signal with the carrier color signal, and a magnetic head that records the low-frequency converted carrier color signal on a magnetic tape. The value obtained by multiplying the ratio to the frequency by 8 is the same as that for the NTSC system.
Slightly different from the case of the PAL method, the value multiplied by 8 above is expressed as the product of prime numbers in either method, so that there is a common prime number among the prime numbers of 3, 5, or 7. , the frequencies of the low-pass conversion carrier color signals of both of the above-mentioned methods are selected, and the low-pass conversion carrier generator includes a frequency divider with a frequency division ratio according to the above-mentioned common prime number, and this frequency divider is A color signal recording device characterized in that it can be operated in either method. 9. The color signal recording device according to claim 8, wherein the low frequency conversion carrier generator includes a 1/8 frequency dividing circuit. 10 Mixing the carrier color signal to be recorded and a low-frequency conversion carrier, converting the carrier color signal into a low-frequency conversion carrier color signal, and recording this converted low-frequency conversion carrier color signal on a magnetic tape. , the value obtained by multiplying the ratio of the frequency of the low frequency conversion carrier to the horizontal frequency by 8 is the same as in the case of the NTSC system.
There is a slight difference between the PAL method and the above value multiplied by 8. In both methods, the value multiplied by 8 is expressed as the product of prime numbers, and it is assumed that there is a common prime number among the prime numbers of 3, 5, or 7. A color signal recording method characterized in that, the frequency of the low-pass conversion carrier color signal of both of the above methods is selected.