JPH0514479B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a video signal recording/reproducing device.

BACKGROUND ART FIG. 13 shows a block system diagram of an example of a conventional video signal recording and reproducing apparatus. First, the operation during recording will be described. A composite color video signal input from an input terminal 1 is supplied to a Y/C separation circuit 2 and separated into a luminance signal Y and a carrier color signal C, respectively. The separated luminance signal passes through an emphasis circuit 3, an FM modulator 4, and a high-pass filter (hereinafter referred to as HPF) 5, respectively, and is supplied to an adder 6 as a frequency-modulated luminance signal (FM luminance signal).

On the other hand, the separated conveyed color signal is transferred to the terminal R during recording.
Through the switch circuit 7 connected to the side
The signal is supplied to the ACC circuit 8, level-adjusted, and then supplied to the balance modulator 9. Further, the horizontal synchronization signal obtained by sequentially passing the separated luminance signal through a switch circuit 10 connected to terminal R and a synchronization separation circuit 11 during recording is a phase comparator 12, an adder 13,
Voltage controlled oscillator (VCO) 14 and counter 15
More Phase Locked Loop (PLL)
PS
The balanced modulator 17 is subjected to known phase shift processing (Phase Shift processing) in which the phase is shifted by 90° every horizontal scanning period by the processing circuit 16 and the direction of the phase shift is reversed every field. supplied to Note that since the switch 24 is open during recording, the adder 13 does not perform an addition operation during recording.

Balanced modulator 17 adjusts the color subcarrier frequency of the standard color video signal from oscillator 18 (and thus
A signal with a frequency _S equal to 3.579545 MHz for the NTSC system and 4.433679 MHz for the PAL system, and a signal with a frequency of 40 _H from the PS processing circuit 16, for example.
Performs balanced modulation with the signal that has been subjected to the phase shift processing described above, and supplies the output signal to the balanced modulator 9 through a bandpass filter (hereinafter referred to as BPF) 19 as a signal with a frequency of ( _S + 40 _H ). .
As a result, a low-pass converted carrier color signal having a color sub-carrier frequency of 40 _H and subjected to the phase shift processing described above is extracted from the balanced modulator 9 through a low-pass filter (hereinafter referred to as LPF) 20. This low-frequency conversion carrier color signal is frequency-division multiplexed with the FM luminance signal by an adder 6, and then passed through a recording amplifier 21 to a head 22.
The signal is supplied to the magnetic tape 23, thereby being recorded on the magnetic tape 23.

Next, the operation during playback will be explained. The recorded frequency division multiplexed signal on the magnetic tape 23 is sent to the head 25.
is reproduced by the LPF through the reproduction amplifier 26.
27 and HPF 28, respectively. HPF28
The reproduced FM brightness signal separated by the FM
After being made into a reproduced luminance signal by the demodulator 29, it is supplied to the adder 31 through the de-emphasis circuit 30, and is also supplied to the sync separation circuit 11 through the switch circuit 10. Switch circuit 7 during playback
and 10 are respectively switched and connected to the terminal P side, and
Switch 24 is closed. For this reason, oscillator 1
The output phase error voltage of the phase comparator 32, which corresponds to the phase difference between the output signal of 8 and the reproduced color burst signal output from the burst sampling circuit 35, which will be described later, is supplied to the adder 13 in the PLL through the switch 24. This PLL is phase synchronized with the reproduced horizontal synchronization signal having jitter from the synchronization separation circuit 11,
A signal responsive to the phase shift of the reproduced color burst signal is extracted and supplied to the balanced modulator 17 through the PS processing circuit 16, where it is output to the oscillator 18.
is modulated in a balanced manner with the output signal of The output signal of the balanced modulator 17 is supplied to the balanced modulator 9 through the BPF 19 as a conversion signal with a frequency corresponding to the jitter ( _S + 40 _H ) or a frequency very close to this, and here the LPF 27, the switch circuit 7 and the ACC circuit 8 is sequentially passed through and balanced modulation (frequency conversion) with the reproduced low frequency conversion carrier color signal having jitter.

As a result, the reproduced carrier color signal returned to the original phase in the original band is extracted from the balanced modulator 9 through the BPF 33, and further passed through the comb filter 34 for canceling crosstalk from adjacent tracks. Burst extraction circuit 35
The signal is also supplied to the adder 31, where it is multiplexed with the reproduced luminance signal to form a reproduced composite color video signal and output to the output terminal 36.

By the way, the emphasis circuit 3 and the de-emphasis circuit 30 are shown in FIG. 15A and FIG. 16A, for example.
It is composed of filters using R and C shown in Figure 15B and Figure 16B, respectively, and has complementary characteristics to suppress noise in the high frequency region and improve the S/N ratio. ing. However, this SN
Since the improvement in the signal to noise ratio was not sufficient, an emphasis (sub-emphasis) circuit with non-linear characteristics (emphasis is given to small amplitudes and non-emphasis is applied to large amplitudes) that changes the amount of emphasis according to the level of the input signal was installed to improve the signal-to-noise ratio. Some devices are known that are designed to improve this.

A conventional sub-emphasis circuit will be described below.

FIG. 17 shows a circuit diagram of an example of a sub-emphasis circuit of a conventional device. The video signal input to the terminal 51 is supplied to the limiter 53 via the high-pass filter 52, where the amplitude is limited to the signal shown in FIG. , which is then subtracted from the original video signal to produce the signal shown in _FIG .
The transfer characteristics of this entire circuit at high level and low level are as shown in FIG.

FIG. 20 shows a circuit diagram of another example (feedback type) of the conventional circuit. The video signal input to the terminal 51 is supplied to the limiter 53 via the high-pass filter 57, where the amplitude is limited to the signal shown in FIG. , which is then subtracted from the original video signal to produce the signal shown in _FIG . The transfer characteristics of this entire circuit at high level and at low level are as shown in FIG.

In the conventional circuit shown in FIG. 17, when impulse noise (FIG. 23A) enters, the output of the limiter 3 is as shown in FIG. 23B, and the signal taken out from the output terminal 6 is as shown in FIG. 23C. It will be as shown. On the other hand, in the conventional circuit shown in FIG. 20, when impulse noise (FIG. 24A) enters, the output of the limiter 53 becomes as shown in FIG. 24B, and the output terminal 56
The signal extracted is as shown in FIG. 24C.

Regarding general random noise, as shown in FIGS. 18B and 21B, the conventional circuit shown in FIG. 20 has a smaller residual noise period (t ₂ ) after the edge of the unit step than the conventional circuit shown in FIG. Although it is better than the conventional circuit, it is second-class in terms of impulse noise.
As shown in FIG. 3C and FIG. 24C, the conventional circuit shown in FIG. 17 is better than the conventional circuit shown in FIG. 20 because it does not generate the so-called horizontal noise like the circuit shown in FIG. 20.

As described above, there is no conventional circuit that can effectively deal with both random noise and impulse noise, and this phenomenon becomes more noticeable as the amount of emphasis (amount of noise improvement) is increased.

Problems to be Solved by the Invention Referring back to FIG. 13, the following will explain. In the conventional video signal recording and reproducing apparatus having the configuration shown in FIG.
As the Y/C separation circuit 2, a circuit having the configuration shown in FIG. 14A or B was used. The Y/C separation circuit shown in FIG.
In addition to separating the luminance signal by LPF40,
Although this circuit uses BPF41 to separate and output the carrier color signal, it is not possible to separate and output the high frequency component of the luminance signal that occupies the same band as the carrier color signal, and the carrier color signal cannot be output due to color boundaries. The low frequency component
It sometimes remained in the output luminance signal of the LPF 40 and was output slightly, degrading the image quality.

On the other hand, the Y/C separation circuit shown in FIG. 14B passes the composite color video signal from the input terminal 42 through a comb filter consisting of a 1H delay line 43 and a subtracter 44, separates the carrier color signal, and separates the carrier color signal. of
While outputting to the output terminal 48 through BPF45,
The subtracter 47 subtracts the input composite color video signal through the level adjuster 46 to separate the luminance signal and outputs it to the output terminal 49. However, this Y/C separation circuit has 1H delay line 4.
3 and the subtractor 44 to extract only frequency components that are integer multiples of the horizontal scanning frequency _H and in the vicinity thereof. High-frequency components of the luminance signal that occupy the same band as the carrier color signal can also be waved, but Y/C cannot be separated accurately for composite color video signals related to patterns with low vertical correlation, resulting in a deterioration of image quality. There was a problem with getting it to work.

Furthermore, since the reproduced composite color video signal outputted from the output terminal 36 is a so-called composite signal in which a luminance signal and a carrier color signal are multiplexed, it is difficult to display this reproduced composite color video signal on a monitor on a display device. When dubbing and recording with other VTRs, it is necessary to perform Y/C separation again in these devices, causing the above-mentioned problems.

Next, let's consider the aforementioned sub-emphasis circuit. The transmission band, which was previously around 3MHz, has been changed to
In recent years, various proposals have been made to increase the image quality by shifting the carrier frequency to the higher frequency side, increasing it to approximately 5 MHz or more, and increasing the image quality. deteriorates.

Therefore, it is necessary to increase the amount of emphasis in the sub-emphasis circuit mentioned above, but as mentioned above, if the amount of emphasis is too large, it will not be possible to reduce random noise and impulse noise, and if the amount of emphasis is too large, it will not be possible to reduce the random noise and impulse noise. Y/C
The carrier color signal component in the luminance signal that could not be removed by the separation circuit 2 is amplified by this emphasis amount, which causes a problem in that Y/C mutual interference worsens and image quality deteriorates.

The present invention addresses signal degradation due to Y/C separation,
There is no mutual interference, cross color, dot interference, etc., and on the other hand, even if the amount of emphasis is increased, random noise and irregular noise can be reduced.
It does not generate side-scanning noise and can significantly improve the signal-to-noise ratio.Even if the emphasis amount is increased, there is no carrier color signal that could not be removed with conventional Y/C separation, and high It is an object of the present invention to provide a recording/reproducing device that can obtain high quality images.

Means for Solving the Problems The device of the present invention has a set of input terminals into which a luminance signal and a carrier color signal are input separately, and a time constant circuit that passes the input luminance signal through a high frequency component. This is taken out, amplitude limited, and returned to the input side via a coefficient circuit to be added or subtracted from the input luminance signal.The time constant is Ts, and the amount of emphasis when the input luminance signal is at a small level is X+1. , where T is the time constant corresponding to the frequency at which the emphasis effect starts, there is a sub-emphasis circuit with a ratio linear characteristic set to T>Ts>T/(X+1), and a main emphasis circuit with a linear characteristic that emphasizes the output of the sub-emphasis circuit. an assist circuit; means for generating a frequency modulated luminance signal from the output signal of the main emphasis circuit; means for generating a low-pass converted carrier color signal; means for frequency-division multiplexing the frequency-modulated luminance signal and the low-pass converted carrier color signal; and recording the frequency-division multiplexed signal on a recording medium; means for reproducing the frequency-division multiplexed signal and separating the frequency-modulated luminance signal and the low-pass-converted carrier chrominance signal, respectively; demodulation means for demodulating the separated frequency-modulated luminance signal; a main de-emphasis circuit which is supplied with the output of the demodulation means and has characteristics complementary to the main de-emphasis circuit; and a main de-emphasis circuit which is supplied with the output of the main de-emphasis circuit to obtain a reproduction luminance signal. a sub-emphasis circuit having characteristics complementary to the sub-emphasis circuit; a frequency conversion means for returning the separated low frequency converted carrier color signal to a reproduced carrier color signal of the original band; and output terminals for separately outputting the reproduced luminance signal.

Operation The signal input to the input terminal is generated into the frequency modulated luminance signal and the low frequency converted carrier color signal, and then frequency division multiplexed by the recording means and then recorded on the recording medium. Therefore, in the recording system, the input signal is converted into the frequency division multiplexed signal and recorded without passing through the Y/C separation circuit at all.

In this case, in the sub-emphasis circuit,
Since there is no carrier color signal component in the luminance signal that cannot be removed by the Y/C separation circuit, it is possible to sufficiently increase the amount of emphasis.

On the other hand, in the reproducing system, among the reproduced frequency modulated luminance signal and the reproduced low-pass conversion carrier color signal that are reproduced from the recording medium and separated, the reproduced frequency modulated luminance signal is the reproduced luminance demodulated by the demodulating means. It becomes a signal. Further, the reproduced low-band converted carrier color signal is returned to the reproduced carrier color signal of the original band by the frequency conversion means.

Therefore, even in the reproduction system, the reproduction signal is outputted in the form of a component signal without generating and outputting a multiplexed signal (composite signal) of the luminance signal and the carrier color signal.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a block system diagram of one embodiment of the present invention. In the figure, the same components as those in FIG. 13 are given the same numbers, and their explanations will be omitted. In Figure 1, 1
00 is a luminance signal Y input terminal, and 101 is a carrier color signal C input terminal. The luminance signal input terminal 100 is connected to the main emphasis circuit 3 via a sub-emphasis circuit (non-linear) 60, and
It is connected to the terminal R of the switch 10, which is the same as in the conventional example, and the carrier color signal input terminal 101 is connected to the terminal R of the switch 7, which is the same as in the conventional example.

On the other hand, 102 is a luminance signal output terminal, and 103 is a carrier color signal output terminal. The main day enhancement circuit 30 is connected to the luminance signal output terminal 102 via the sub-day enhancement circuit (non-linear) 61, and each output of the burst sampling circuit 35 and the comb filter 34 is connected to the carrier color signal output terminal. 103
It is connected to the.

Here, the luminance signal Y and the carrier color signal C are input to the input terminals 100 and 101 in a separately separated state. In this case, the deviation of the FM modulation is
It is assumed that the frequency is set between 5.4MHz and 7MHz. The luminance signal and the carrier color signal are supplied to the respective recording circuits in the same way as in the conventional circuit, and are balanced-modulated by the balanced modulator 9, resulting in a low-frequency converted carrier color signal and the HPF via the sub-emphasis circuit 60, which will be described later.
The FM luminance signal taken out from 5 is frequency-division multiplexed by an adder 6 as in the prior art, and then recorded on a magnetic tape 23 by a head 22.

With this, for example, the output signal of a VTR that outputs a reproduced luminance signal and a reproduced carrier color signal without converting it into a composite signal during reproduction can be transferred to the input terminal 10.
By inputting signals to 0 and 101 respectively, dubbing can be recorded on the magnetic tape 23 as a frequency division multiplexed signal of a predetermined standard without converting it into a composite signal, and in this case, the image quality deteriorates due to the Y/C separation described above. It is possible to perform dubbing recording with good image quality without any problems.

Next, to explain the operation during reproduction, the reproduced carrier color signal taken out from the comb filter 34 is sent to the output terminal 103 along with the output of the burst sampling circuit 35.
taken out from On the other hand, a main day emphasis circuit 30 and a sub day emphasis circuit 6 to be described later.
The reproduced luminance signal that has passed through 1 is taken out from the output terminal 102.

In this case, the reproduced video signal is not combined,
Since the carrier color signal and the luminance signal are in the form of component signals that are transmitted separately and simultaneously, there is no mutual interference caused by the combination of the luminance signal and the carrier color signal as in the prior art. In addition, output terminal 10
The output signals 2 and 103 are output to be dubbed and recorded on another VTR.

Next, the operations of the sub-emphasis circuit 60 and the sub-emphasis circuit 61 in FIG. 1 will be explained.

FIGS. 2A and 2B show circuit diagrams of a first embodiment of sub-emphasis circuits 60 and 61 applied to the apparatus of the present invention, respectively. The time constant of the high-pass filter 72 in the sub-emphasis circuit 60 (recording section) shown in FIG. 2A is Ts, and the coefficient of the coefficient circuit 73 is approximately X.
Letting T be the time constant corresponding to the frequency at which the emphasis effect starts, it is set as T>Ts>T/(X+1) (1). As a result, the transfer characteristics of the entire circuit at high level and at low level are as shown in FIG. 5A.

In FIG. 2A, the video signal a ₁ (FIG. 3A) inputted to the terminal 71 is converted into the signal c ₁ by the high-pass filter 72.
(FIG. 3C), and the amplitude is limited by the limiter 74 to produce a signal d ₁ (FIG. 3D). The signal d ₁ is supplied to an adder 76 via a coefficient circuit 75 for setting a time constant, in which a coefficient K is set, and is made into a signal b ₁ (FIG. 3B), while a coefficient X is set. The signal is supplied to an adder 77 via a coefficient circuit 73 for setting the amount of emphasis, and outputted from an output terminal 78 as a signal e ₁ (E in FIG. 3). As shown in FIG. 3C, the time constant immediately after the waveform falls is T≈Ts, and the time constant thereafter is T=(1/1+K)Ts.

Next, impulse signal a ₂ is applied to terminal 71 (Fig. 4A).
When the signal enters, the high-pass filter 72 converts it into a signal C ₂ (FIG. 4C), and the limiter 74 limits the amplitude to generate a signal d ₂ (FIG. 4D). The signal d ₂ is supplied to the adder 76 via the coefficient circuit 75 to generate the signal b ₂
(FIG. 4B), and is also supplied to the adder 72 via the coefficient circuit 73 and outputted from the output terminal 78 as a signal e ₂ (FIG. 4E).

Let Ts be the time constant of the high-pass filter 72 in the sub-day emphasis circuit (reproduction system) shown in FIG. 2B, X be the coefficient of the coefficient circuit 79, and T be the time constant corresponding to the frequency at which the noise reduction effect begins. , T>Ts>T/(X+1) (1). As a result, the transfer characteristics of the entire circuit at high level and at low level are as shown in FIG. 5B.

Here, in Figure 2 A and B, the time constant Ts is
When Ts={(K+1)/(X+1)}T, the range of K of the coefficient circuit 75 is set to O<K<X in order to satisfy the above equation (1). The transfer function of the circuit in Figure 2B is as follows: OUT/IN=1+{1/(1+K)}Ts/1+{(1+
K)/(1+K)}Ts, and the transfer function of the circuit of FIG. 2A is the reciprocal of the above equation.

In FIG. 2B, the video signal a ₃ (FIG. 6A) input to the terminal 71 is converted into the signal c ₃ by the high-pass filter 72.
(FIG. 6C), and the amplitude is limited by the limiter 80 to produce a signal d ₃ (FIG. 6D). The signal d ₃ is supplied to an adder 81 via a coefficient circuit 75 for setting a time constant, in which a coefficient K is set, and is made into a signal e ₃ (Fig. 6E), while a coefficient X is set. It is supplied to the subtracter 82 via a coefficient circuit 79 that sets the amount of noise reduction (de-emphasis amount), and is taken out from the output terminal 78 as a signal b ₃ (FIG. 6B). As shown in Figure 6C, the time constant immediately after the fall of the waveform is T≒Ts, and the time constant after that is T
= {(1+K)/(1+K)}Ts.

As described above, since the present invention uses a feedback type circuit, as for random noise, unlike the conventional circuit shown in FIG. 20, the time during which the noise remains is short.

Next, when impulse noise a ₄ (A in FIG. 7) enters the terminal 71, the high-pass filter 72 outputs the signal c ₄
(FIG. 7C), and the amplitude is limited by the limiter 80 to produce a signal d ₄ (FIG. 7D). The signal _d4 is supplied to the adder 81 via the coefficient circuit 75, and the signal
e ₄ (Fig. 7E), while being supplied to the subtracter 82 via the coefficient circuit 79 and the signal b ₄ (Fig. 7B)
and is taken out from the output terminal 78. In this case, the time constant Ts of the high-pass filter 72 is set to T>Ts>
Since it is set as T/(X+1), the waveform after the fall of the output d ₄ of the limiter 80 (D in FIG. 7) can be improved compared to the conventional circuit shown in FIG. As shown in FIG. 24B, so-called horizontal noise as shown in FIG. 24C is hardly generated.

In addition, in the case of a noise canceller that is performed only on the playback side of a VTR, the coefficient It is.

FIGS. 8A and 8B show circuit diagrams of a second embodiment of the sub-emphasis circuit applied to the device of the present invention. Similarly to the first embodiment, the sub-emphasis circuit (recording system) shown in FIG.
It is assumed that Ts is set as shown in equation (1) above, and the transfer characteristics of the entire circuit are as shown in FIG. 5A.

The video signal that enters the terminal 71 is passed through the high-pass filter 7.
2 to a limiter 83 where the amplitude is limited, and then supplied to a subtracter 85 via a coefficient circuit 84 that sets a time constant having a coefficient k set therein. The output of the limiter 83 is taken out from the output terminal 78 via a coefficient circuit 86 and an adder 87, which set the amount of emphasis set to a coefficient X/(X+1).

Similarly to the first embodiment, the sub-emphasis circuit (reproduction system) shown in FIG. As shown below.

The video signal that enters the terminal 71 is passed through the high-pass filter 7.
2 to a limiter 83 where the amplitude is limited, and then supplied to a subtracter 85 via a coefficient circuit 84 that sets a time constant having a coefficient k set therein. The output of the limiter 83 is taken out from the output terminal 78 via a subtracter 88 and a coefficient circuit 86 that sets a noise reduction amount (de-emphasis amount) set to a coefficient X/(X+1).

Here, in Fig. 8A and B, the time constant Ts is
When Ts=(1-k)T, the range of k of the coefficient circuit 84 must be O<k<
Set to {X/(X+1)}. The transfer function of the circuit in Figure 8B is: OUT/IN = 1+{1/(1-k)(X+1)}Ts/1+{
1/(1-k)}Ts, and the transfer function of the circuit of FIG. 8A is the reciprocal of the above equation.

FIGS. 9A and 9B show circuit diagrams of a third embodiment of a sub-emphasis circuit applied to the apparatus of the present invention. In FIGS. 9A and 9B, the high-pass filter 72 in FIGS. 8A and B is replaced with a high-pass filter 89, and the coefficient circuit 86 in FIGS. 8A and B is replaced with a coefficient circuit 90 of coefficient (1+K)X/(X+1). This is what I did. In Figures 9A and B,
The time constant Ts of the high-pass filter 89 is Ts={1/(1
+K)}T, the range of K of the coefficient circuit 90 is set to O<K<X in order to satisfy the above equation (1). The transfer function of the circuit in Figure 9B is: OUT/IN=1+{(K+1)/(X+1)}Ts/1+
(1+K)Ts, and the transfer function in FIG. 9A is the reciprocal of the above equation.

FIGS. 10A and 10B show circuit diagrams of a fourth embodiment of the sub-emphasis circuit applied to the device of the present invention.
In FIG. 10A, the high-pass filter 72 in FIG. 8B is replaced by a high-pass filter 89, the coefficient circuit 86 in FIG. 8B is replaced by a coefficient circuit 91 of coefficient (1-k)X, and the subtracter in FIG. 85 and 88 are adders 87 and 92, and FIG. 10B is the high-pass filter 7 of FIG. 8A.
2 is a high-pass filter 89, the coefficient circuit 86 in FIG. 8A is a coefficient circuit 91, and the adder 8 in FIG.
7. The subtracter 85 is replaced by a subtracter 85 and an adder 92, respectively.

In FIGS. 10A and 10B, the time constant Ts of the high-pass filter 89 is Ts=[{1/{(1-K)(X+1)}]
In the case of T, the range of k of the coefficient circuit 84 is set to O<K<(X/X+1) in order to satisfy the above equation (1). The transfer function of the circuit in Figure 10B at small amplitude is OUT/IN=1+(1-K)Ts/1+(1-K)(X+
1) Ts, and the transfer function in FIG. 10A is the reciprocal of the above equation.

Incidentally, as shown in FIG. 11A, the recording system circuit may be arranged such that the circuit shown in the second to fourth embodiments is provided in the return path of the operational amplifier 94 as the reproducing circuit 93. In addition, as shown in Figure B, the reproduction system circuit is the first
The recording circuit 96 shown in the fourth embodiment may also be provided in the return path of the operational amplifier 94.

In addition, as shown in Figure 12, the recording system (sub-emphasis circuit) and the reproduction system (sub-emphasis circuit)
may be used for both in one circuit. During recording, the switch 95 is turned off and the recording output is taken out from the output terminal _78R , while during reproduction, the switch 95 is turned on and the playback output is taken out from the output terminal _78P .

Effects of the Invention According to the device of the present invention, a predetermined frequency division multiplexed signal can be generated based on an input signal without ever separating a luminance signal and a carrier chrominance signal from a composite signal that is band-sharing multiplexed. Since it is recorded, signal deterioration due to Y/C separation can be completely eliminated, and signals of good image quality can be recorded and dubbed.Also, luminance signals and carriers can be separated without Y/C separation. Since the color signal and the color signal are output separately, there is no signal deterioration due to Y/C separation or mutual interference due to the combination of two signals, and there is no crosstalk caused by incomplete Y/C separation. Since there is no interference such as color or dot interference, it is possible to reproduce and display high-quality color images.Also, since the sub-emphasis circuit uses a feedback type, the residual noise period after the edge can be reduced against random noise. In addition, since the time constant Ts of the time constant circuit is set as T>Ts>T/(X+1), the waveform after the fall of the limiter output can be changed to the conventional feedback form for impulse noise. This can be improved over the noise reduction circuit of
So-called horizontal noise does not occur, and overall, even if the amount of sub-emphasis is increased, both random noise and impulse noise can be effectively dealt with, and a high S/N ratio can be achieved. Y/C that conventionally existed in signals
Since there are no carrier color signal components that could not be removed by separation, even if the amount of sub-emphasis is increased, the deterioration in image quality caused by this can be eliminated. Therefore, wideband recording/playback is possible, and ultra-high resolution and ultra-high You can get high quality VTR.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram of an embodiment of the device of the present invention, FIG. 2 is a circuit diagram of a first embodiment of a sub-emphasis circuit applied to the device of the present invention, and FIGS. 3 and 4 are diagrams of the device of the present invention. A signal waveform diagram for explaining the operation of the recording system of the sub-emphasis circuit; FIG. 5 is a transfer characteristic diagram of the device of the present invention; FIGS. 6 and 7 are signal waveform diagrams for explaining the operation of the reproduction system of the sub-emphasis circuit of the device of the present invention; 8 to 10 are circuit diagrams of second to fourth embodiments of the sub-emphasis circuit of the device of the present invention, FIG. 11 is a circuit diagram in which a reproducing circuit or a recording circuit is provided in the return path of an operational amplifier, and FIG. The figure shows a circuit diagram in which a single circuit serves as a sub-emphasis circuit for both the recording system and the reproduction system, Figure 13 is a circuit diagram of an example of a conventional circuit, Figure 14 is a circuit diagram of a conventional Y/C separation circuit, and Figure 15 , FIG. 16 is a circuit diagram of a conventional emphasis circuit and de-emphasis circuit, FIG. 17 is a circuit diagram of an example of a conventional sub-emphasis circuit, and FIGS. 18 and 19 are signal waveform diagrams and transmission of the circuit shown in FIG. 17, respectively. FIG. 20 is a circuit diagram of another example of the conventional sub-emphasis circuit, FIGS. 21 and 22 are signal waveform diagrams and transfer characteristic diagrams of the circuit shown in FIG. 20, and FIGS. 23 and 24 are FIG. 22 is a signal waveform diagram of the circuit shown in FIG. 17 and the circuit shown in FIG. 20, respectively. 3...Main emphasis circuit, 4...FM modulator, 9, 17...Balanced modulator, 27...Low-pass filter (LPF) for low-pass conversion carrier color signal separation, 28
...High-pass filter (HPF) for frequency modulated luminance signal separation, 29...FM demodulator, 30...Main day emphasis circuit, 60...Sub emphasis circuit, 61...Sub day emphasis circuit, 7
2, 89...High frequency filter, 73, 75, 79,
84, 86, 90, 91... Coefficient circuit, 74, 8
0,83...Limiter, 100...Luminance signal input terminal, 101...Carrier color signal input terminal, 102...
...Reproduction luminance signal output terminal, 103...Carrier color signal output terminal.

Claims (1)

[Claims] 1. A set of input terminals into which a luminance signal and a carrier chrominance signal are input separately, and the input luminance signal is taken out via a time constant circuit that passes high frequency components and amplitude limited, This is fed back to the input side via a coefficient circuit and added or subtracted from the input luminance signal.The time constant of the time constant circuit is Ts, the amount of emphasis when the input luminance signal is at a small level is X+1, and the emphasis effect is Let T be the time constant corresponding to the frequency at which means for generating a frequency-modulated luminance signal from the output signal of the main emphasis circuit; and a low-pass conversion carrier occupying a band lower than the frequency-modulated luminance signal from the carrier chrominance signal input to the input terminal. An image comprising: means for generating a color signal; and means for frequency-division multiplexing the frequency-modulated luminance signal and the low-pass conversion carrier color signal, and recording the frequency-division multiplexed signal on a recording medium. Signal recording device. 2. A set of input terminals into which the luminance signal and the carrier color signal are input separately, and the input luminance signal is taken out via a time constant circuit that passes high frequency components to limit the amplitude, and is sent via a coefficient circuit. The configuration is such that the time constant is Ts, and the amount of emphasis when the input brightness signal is at a small level is X.
+1, and if T is the time constant corresponding to the frequency at which the emphasis effect starts, then there is a sub-emphasis circuit with non-linear characteristics set to T>Ts>T/(X+1), and a main emphasis circuit with linear characteristics that emphasizes the output of the sub-emphasis circuit. an assist circuit; means for generating a frequency modulated luminance signal from the output signal of the main emphasis circuit; means for generating a low-pass converted carrier color signal; means for frequency-division multiplexing the frequency-modulated luminance signal and the low-pass converted carrier color signal and recording the frequency-division multiplexed signal on a recording medium; and the recording medium. means for reproducing the frequency-division multiplexed signal and separating the frequency-modulated luminance signal and the low-pass converted carrier chrominance signal, respectively; demodulation means for demodulating the separated frequency-modulated luminance signal; a main day emphasis circuit which is supplied with the output of said demodulation means and has characteristics complementary to said main emphasis circuit; and said main day emphasis circuit which is supplied with the output of said main day emphasis circuit to obtain a reproduced luminance signal. a sub-emphasis circuit having complementary characteristics to the sub-emphasis circuit; a frequency conversion means for returning the separated low frequency converted carrier color signal to a reproduced carrier color signal of the original band; A recording/reproducing device for a video signal, comprising an output terminal that separately outputs the reproduced luminance signal.