JP2744121B2 - Signal processing circuit of recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus for recording / reproducing a color video signal, and in particular, to reduce mutual interference between a luminance signal and a color signal of the color video signal. The present invention relates to a signal processing circuit.

2. Description of the Related Art In a 2-head helical scan type magnetic recording / reproducing apparatus (hereinafter, referred to as VTR), when recording a color video signal, a luminance signal and a chroma signal are separated from the color video signal by a Y / C separation circuit. Separate and convert the chroma signal to low frequency by performing FM modulation on the luminance signal. After that, the luminance signal subjected to FM modulation (hereinafter referred to as FM luminance signal) and the low-frequency converted chroma signal (hereinafter referred to as low-frequency conversion chroma Signal) is recorded on a magnetic tape by frequency division multiplexing. During playback, the FM luminance signal and the low-frequency conversion chroma signal are separated from the reproduced signal, After the frequency conversion of the band-converted chroma signal into the original frequency band, the obtained luminance signal and chroma signal are added to obtain a color video signal.

By the way, conventionally, as a Y / C separation circuit, an LPF (Low Pass Filter) is used to separate a luminance signal from a color video signal, and a BPF is used to separate a chroma signal.
(Bandpass filter) is used, but according to this, the high frequency component of the luminance signal is lost. Therefore,
Recently, a VTR has been developed in which a comb filter is used as a Y / C separation circuit to separate and record and reproduce a broadband luminance signal to obtain a high horizontal resolution.

However, if the separation performance of the Y / C separation circuit using the comb filter is not sufficient, a chroma signal remains in the separated luminance signal (hereinafter, this chroma signal is referred to as a residual chroma component), which causes color flicker and zero beat. There is a problem that occurs. In other words, although the reproduced signal from the magnetic tape has a time axis fluctuation due to jitter or the like, the reproduced chroma signal is subjected to frequency conversion of the low-frequency converted chroma signal with an output signal of an APC (automatic phase control) circuit. In this case, the time axis fluctuation is removed. On the other hand, since such a process of correcting the time axis fluctuation is not performed on the reproduced luminance signal, the residual chroma component in the luminance signal has a time axis fluctuation, and When the obtained luminance signal and chroma signal are added, the chroma signal and the residual chroma component interfere with each other to generate color flicker and zero beat.

As a technique for preventing such mutual interference, a technique has been known in which a reproduced luminance signal is supplied to a comb filter to remove a residual chroma component, and then added to the reproduced chroma signal (see, for example, Japanese Patent Application Laid-Open No. H11-157556). For example, JP-A-63-2718
No. 8). According to this, it is possible to suppress interference such as color flicker while maintaining a high horizontal resolution.

[Problems to be Solved by the Invention] By the way, when a luminance signal is passed through a comb filter, there is no deterioration in horizontal resolution, but there are deterioration in diagonal resolution and erroneous processing in a vertical decorrelation part. Image quality degradation occurs. Therefore, if the reproduced luminance signal is processed by the comb filter as in the above-described conventional technique, the image quality is inevitably deteriorated.

Moreover, in recent television receivers, a comb filter is mainly used as a Y / C separation circuit for separating a luminance signal and a chroma signal from an input color video signal. Therefore, when a color video signal output from the conventional VTR is supplied to such a television receiver,
The luminance signal in the color video signal has been processed by the two comb filters on the VTR side and the television receiver side, and the image quality is significantly deteriorated.

In addition, the comb filter has an expensive 1H delay circuit for delaying the signal by 1H (1H is one horizontal scanning period). Therefore, in the above-described conventional VTR, in addition to the recording system, the reproduction is performed in addition to the recording system. The system also requires an expensive 1H delay circuit.

An object of the present invention is to solve such a problem and to suppress the interference between the residual chroma signal and the chroma signal in the luminance signal while avoiding the image quality deterioration due to the deterioration of the horizontal resolution and the oblique resolution by using inexpensive means. It is another object of the present invention to provide a signal processing circuit of a recording / reproducing apparatus which can perform the above processing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a band including a residual chroma component of a reproduced luminance signal (hereinafter, referred to as a chroma band), the level of the luminance component in the band. A variable trap circuit is provided so that the amount of attenuation is increased as the value is lower, and a color video signal is obtained by adding the output luminance signal of the variable trap circuit and the reproduced chroma signal.

[Operation] When the level of the luminance signal in the chroma band is high, even if color flicker occurs due to interference between the residual chroma component in the luminance signal and the chroma signal, it is not visually noticeable.
The lower the level of the luminance signal in the chroma band, the more noticeable the color flicker.

Therefore, when the level of the luminance signal in the chroma band is low, the amount of attenuation of the variable trap circuit is increased to sufficiently suppress the residual chroma component in the luminance signal so that color flicker and the like are not conspicuous. When the luminance signal is high, the attenuation of the variable trap circuit is reduced,
This luminance signal is not greatly attenuated. As a result, deterioration of the horizontal resolution can be prevented.

That is, when the chroma band is attenuated by the variable trap circuit, the luminance component in the chroma band is also attenuated, and the horizontal resolution is deteriorated. When the level of the luminance signal in the chroma band is low, color flicker and the like are conspicuous, but the luminance component in the chroma band is small and the horizontal resolution is originally low. Therefore, even if the horizontal resolution deteriorates due to the attenuation in the variable trap circuit, since the horizontal resolution is originally low, the deterioration in the horizontal resolution is inconspicuous. For this reason, the amount of attenuation of the variable trap circuit is increased so as to suppress conspicuous color flicker and the like.

On the other hand, when the luminance signal level in the chroma band is high, the color flicker and the like are originally inconspicuous. Therefore, even if the attenuation of the variable trap circuit is increased, the effect on the color flicker and the like does not appear. Rather, the luminance component in the chroma band is greatly attenuated by increasing the amount of attenuation of the variable trap circuit, and the horizontal resolution is noticeably deteriorated. For this purpose, the attenuation of the variable trap circuit is reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking a VTR as an example.

FIG. 1 is a block diagram showing an embodiment of a signal processing circuit of a recording / reproducing apparatus according to the present invention.
Is an AGC (automatic gain control) circuit, 3 is a Y / C separation circuit, 4 is a pre-emphasis circuit, 5 is an FM modulation circuit, 6 recording equalizers, 7 is an adder, 8 is a recording amplifier, 9 is a switch, 10
Is a rotating magnetic head, 11 is a reproduction amplifier, 12 is an FM equalizer, 13 is a limiter circuit, 14 is an FM demodulation circuit, 15 is a de-emphasis circuit, 16 is an output terminal, 17 is a dynamic trap circuit, 18 is an adder, 19 , 20 are output terminals, 21, 22 are LPF, 2
3 is a frequency converter, 24 ACC (automatic color control) circuits, 25 is a switch, 26 is a C-shaped comb filter, and 27 is BP
F and 28 are input terminals.

In the figure, at the time of recording, the switches 9 and 25 are closed on the REC side.

The color video signal input to the input terminal 1 is made to have a constant amplitude by the AGC circuit 2, and then a Y /
The signal is separated into a wideband luminance signal Y and a chroma signal C by a C separation circuit 3. This luminance signal Y is processed by a pre-emphasis circuit 4 and then modulated by an FM modulation circuit 5 to become an FM luminance signal Y _FM , processed by a recording equalizer 6 and processed by an adder 7.
Supplied to The chroma signal C passes through a switch 25, is processed by an ACC circuit 24, is frequency-converted by a converted signal from an input terminal 28 by a frequency converter 23, and unnecessary components are removed by an LPF 22 to convert the low-frequency converted chroma signal. the C _L. This low-frequency conversion chroma signal C _L is recorded by an adder 7 into a recording equalizer 6.
Is added to the FM luminance signal Y _FM .

Frequency division multiplex signal with FM luminance signal Y _FM and the low frequency converted chrominance signal C _L which is output from the adder 7 is amplified by the recording amplifier 8 is supplied to the rotary magnetic head 10 via the switch 9, It is recorded on a magnetic tape (not shown).

Next, during reproduction, the switches 9, 25 are closed to the PB side.

The reproduction signal from the magnetic tape by the rotating magnetic head 10 passes through the switch 9 and is amplified by the reproduction amplifier 11.
It is supplied to the FM equalizer 12 and the LPF 21. FM equalizer 1
In 2, FM luminance signal Y _FM from the reproduced signal is separated, the amplitude difference by the characteristics difference of the two rotary magnetic heads 10 used is corrected. FM luminance signal output from FM equalizer 12
Y _FM is amplitude-limited by a limiter circuit 13 and demodulated to a baseband luminance signal Y by an FM demodulation circuit 14. This luminance signal Y is processed by a de-emphasis circuit 15 having a characteristic opposite to that of the pre-emphasis circuit 4, and is output from an output terminal 16.

In the LPF 21, the reproduced signal is converted from the low-frequency converted chroma signal C.
_L is separated. The low-frequency conversion chroma signal C _L passes through a switch 25, is processed by an ACC circuit 24, and is frequency-converted by a frequency converter 23 using a conversion signal from an input terminal 28.
Unnecessary components are removed by the BPF 27 to become the chroma signal C in the original frequency band. This chroma signal C is a C-shaped comb filter 26.
To remove the crosstalk component from the adjacent track on the magnetic tape, and output from the output terminal 20.

Luminance signal Y output from day-emphasis circuit 15
Is further processed by a dynamic trap circuit 17 and added to a chroma signal C output from a C-shaped comb filter 26 by an adder 18. The color video signal obtained by this addition processing is output from the output terminal 19.

 The above is the schematic operation of this embodiment.

By the way, if the separation performance of the Y / C separation circuit 3 composed of a comb filter is not sufficient, the luminance signal Y separated by this has a residual chroma component. Therefore, when reproducing a magnetic tape on which the luminance signal Y and the chroma signal C have been processed as described above and recorded, the luminance signal Y reproduced from the magnetic tape must have a residual chroma component. become. The VTR can reproduce a magnetic tape recorded on another VTR. For this,
Even if the separation performance of the Y / C separation circuit 3 is sufficient, if there is a residual chroma component in the luminance signal recorded on the magnetic tape to be reproduced, the luminance signal reproduced from this magnetic tape is There is a residual chroma signal.

Meanwhile, although not shown, converts the signal inputted from the input terminal 28 an input color burst signal of the chroma signal C outputted from the color burst signal or BPF27 of the low frequency converted chrominance signal C _L which is input to the frequency converter 23 AP to do
Generated by the C circuit, and a phase lock in the low-band converting chrominance signal C _L or chroma signal C. As a result, in the chroma signal C output from the C-shaped comb filter 26, the time axis fluctuation due to jitter or the like generated during reproduction is removed. On the other hand, since the reproduced luminance signal Y output from the day-emphasis circuit 15 has not undergone such processing for time-axis fluctuation correction, it has undergone time-axis fluctuation, and The existing residual chroma components also undergo the same time axis fluctuation. Therefore, when the chroma signal C and the luminance signal Y are directly added to form a color video signal, a residual chroma component whose frequency fluctuates due to a time axis fluctuation in the luminance signal Y and a time axis fluctuation are removed. When the chroma signal C interferes with each other, color flicker and zero beat occur.

In this embodiment, a dynamic trap circuit 17 is provided to prevent this. This dynamic trap circuit 17 is used to control the color subcarrier frequency of the chroma signal C.
f _SC (f _SC = 3.58 MHz in NTSC system; f _SC = 4.4 in PAL system)
(3 MHz), and has a trapping characteristic in the vicinity of the color subcarrier frequency f _SC , that is, in the chroma band, and the degree of attenuation changes according to the amplitude of the input signal.

That is, the luminance signal Y output from the de-emphasis circuit 15 is trapped by the dynamic trap circuit 17 and added to the chroma signal C output from the C-comb filter 26 by the adder 18 to form a color video signal. However, when the amplitude of the luminance signal Y in the chroma band is small, the attenuation of the dynamic trap circuit 17 increases. As a result, the luminance component of the luminance signal Y in the chroma band is attenuated, but the residual chroma component present in this chroma band is also sufficiently attenuated, and color flicker and zero beat are suppressed. On the other hand, when the amplitude of the luminance signal Y in the chroma band is large, the attenuation of the dynamic trap circuit 17 becomes small, and the attenuation of the signal component in the chroma band becomes small.

The color flicker and the zero beat are generated irrespective of the amplitude of the luminance component in the chroma band of the luminance signal Y if the residual chroma component exists in the luminance signal Y. However, from a visual point of view, color flicker and zero beat are very conspicuous when the amplitude of the luminance component in the chroma band is small, but become inconspicuous when the amplitude is large.

Therefore, when the amplitude of the luminance component in the chroma band of the luminance signal Y is small, the degree of attenuation of the dynamic trap circuit 17 is increased, so that the residual chroma component is sufficiently attenuated, and color flicker and zero beat become inconspicuous. At this time, the luminance component of the luminance signal Y in the chroma band is also attenuated and the horizontal resolution is affected. However, since this luminance component has a small amplitude from the beginning, even if this is attenuated, the horizontal resolution is hardly deteriorated. It is negligible. When the luminance component of the luminance signal Y in the chroma band has a large amplitude, the color flicker and the zero beat are hardly noticeable, so that the dynamic trap circuit 17 does not need to attenuate the residual chroma component in the luminance signal Y. Rather, when the residual chroma component is attenuated, the luminance component of the luminance signal Y in the chroma band is also attenuated, and the originally high horizontal resolution is deteriorated.

As described above, in this embodiment, the dynamic trapping circuit 17 processes the luminance signal Y to generate a color video signal, so that the residual chroma in the luminance signal Y is not affected by the horizontal resolution. Color flicker and zero beat due to mutual interference between the signal and the chroma signal can be made inconspicuous. In addition, the deterioration of the oblique resolution and the erroneous processing operation in the vertical non-correlation part when the comb filter is used as in the above-mentioned prior art do not occur, and a reproduced image of good image quality can be obtained.

FIG. 2 shows the dynamic trap circuit 17 in FIG.
FIG. 13 is a block diagram showing a specific example of the embodiment, in which 29 is an input terminal,
30 is an output terminal, 31 and 32 are subtractors, 33 is a trap circuit, 34
Is a limiter circuit, and 35 is an attenuation circuit.

In the figure, a reproduced luminance signal Y output from a de-emphasis circuit 15 (FIG. 1) is input from an input terminal 29 and supplied to subtracters 31, 32 and a trap circuit 33. A trap circuit 33 a trap chroma band of the reproduced luminance signal Y around the color sub-carrier frequency f _SC. In the subtractor 32,
The output signal of the trap circuit 33 is subtracted from the input reproduced luminance signal Y, and a signal component in the chroma band of the reproduced luminance signal Y (hereinafter referred to as a chroma band component) is obtained.

The chroma band component of the reproduced luminance signal Y obtained from the subtractor 32 is supplied to a limiter circuit 34. The limiter circuit 34 has a non-linear limiter characteristic, and receives the input reproduced luminance signal Y.
The greater the amplitude of the chroma band component is, the more the amplitude is limited. That is, as the amplitude of this component increases, the ratio of the output amplitude to the input amplitude of the limiter circuit 34 decreases,
As the input amplitude decreases, the output amplitude equals the input amplitude. The output signal of the limiter circuit 34 is supplied to the attenuator 31 via the attenuator 35. The output signal of the attenuator 35 is subtracted from the input reproduced luminance signal Y by the subtracter 31, and the subtracted signal is supplied from the output terminal 30 to the adder 17 in FIG.

FIG. 3 shows the frequency characteristics of the dynamic trap circuit 17 shown in FIG. 2 when the gain of the limiter circuit 34 is about 30 dB.

When the attenuation characteristic of the output is shown with respect to the chroma band component of about 0 to -30 dB of the input reproduced luminance signal Y, as shown in the figure, the smaller the input amplitude, the greater the degree of attenuation. For example, if the attenuation of the attenuator 35 is appropriately selected, the attenuation of the above-mentioned chroma band component of the dynamic trap circuit 17 is within 1 dB for 0 dB input and 3 d for -10 dB input.
B, 10dB for -20dB input, 20dB for -30dB input
You can choose to a degree.

Generally, Y / C consisting of the comb filter shown in FIG.
The degree of attenuation of the residual chroma component in the luminance signal Y of the separation circuit 3 is about 30 dB depending on the adjustment accuracy. The luminance signal Y and the chroma signal C are recorded / reproduced as described above, and simply added to obtain a color video signal. Is formed, interference such as color flicker can be visually detected. According to the results of the experiment, if the degree of attenuation of the residual chroma component is about 45 dB or more, interference such as color flicker is hardly a problem.

Therefore, by setting the characteristic of the dynamic trap circuit 17 so as to obtain an attenuation of about 20 dB as described above with respect to the residual chroma component of -30 dB, the residual chroma component in the reproduced luminance signal Y is reduced. It can be suppressed to -50 dB or less, and interference such as color flicker is not a visual problem.

Further, for the chroma band component having a large amplitude of about 0 to -10 dB, the attenuation of the dynamic trap circuit 17 can be suppressed to about 1 to 3 dB, so that the deterioration of the horizontal resolution can be almost ignored. In addition, since processing using the correlation between 1H such as a comb filter is not performed, there is no deterioration in the oblique resolution and no erroneous processing in the vertical non-correlation part.

FIG. 4 shows the dynamic trap circuit 17 shown in FIG.
FIG. 3 is a circuit diagram showing a specific circuit configuration of FIG.

In the figure, a portion surrounded by a broken line constitutes a trap circuit 33, and transistors Q2, Q3, resistors R4, R5, R6 and current sources I2, I3 constitute a subtractor 32. Input terminal 29
The reproduced luminance signal input from the
Supplied from the emitter of Q1 to the base of transistor Q2,
On the other hand, from the emitter of the transistor Q1 to the trap circuit 33
, And is supplied to the transistor Q3 to perform a subtraction process.

The transistors Q5 and Q6, the resistor 12, the current sources I5 and I6, and the switch S1 constitute a limiter circuit. Also, transistors Q7, Q8, resistors R13, R15, R16, R17, R18 and current source I
7, I8 constitute a subtractor 31, and resistors R15, R16, R17, R18
Corresponds to the attenuation circuit 35. The amount of attenuation is resistance R16 and R15,
It is determined by the ratio between the resistors R17 and R18. In addition, the limiter circuit 34
Is a current limiting type limiter circuit which is limited by the currents of the current sources I5 and I6.

The switch S1 is for enabling the limiter circuit 34 to be turned on and off. When the residual chroma component in the luminance signal due to the Y / C separation is sufficiently attenuated, the dynamic trap circuit 17 becomes unnecessary, and when such a luminance signal is passed through the dynamic trap circuit 17, the chroma band component is removed. Is attenuated and the definition of the image is degraded.
Therefore, when the residual chroma component is sufficiently suppressed and the luminance signal is reproduced, the limiter circuit 34 is switched by the switch S1.
Is turned off to prevent the dynamic trapping circuit 17 from performing a trapping operation, thereby preventing deterioration in image definition.

For example, in FIG. 1, when the separation performance of the Y / C separation circuit 3 is high and the residual chroma component is sufficiently suppressed to separate the luminance signal, the magnetic tape processed and recorded by such a recording system is reproduced. In this case, the residual chroma component of the luminance signal output from the de-emphasis circuit 15 is sufficiently suppressed.In such a case, the switch S1 is opened to turn off the limiter circuit 34, and the dynamic trap circuit 17 What is necessary is just to make it not operate. Conversely, if the reproduced image is degraded due to color flicker, such as when reproducing a magnetic tape recorded on another VTR, the switch S1 is closed, the limiter circuit 34 is turned on, and dynamic trapping is performed. What is necessary is just to make the circuit 17 perform a trap operation. The switch S1 is controlled by a control signal input from the input terminal 36 in response to a user operation or the like.

FIG. 5 is a circuit diagram showing an example of a band elimination filter (BEF). FIG. 6 shows the frequency characteristics of this BEF.

Such a BEF can be used in place of the trap circuit 33 in FIG. According to this, the dynamic trap circuit 17 can have an attenuation characteristic in the chroma band of f _SC ± 500 KHz, and the residual chroma component can be attenuated in a wide band.

FIG. 7 shows the dynamic trap circuit 17 in FIG.
FIG. 14 is a block diagram showing another specific example, in which 41 is a tank circuit, and portions corresponding to FIG. 2 are denoted by the same reference numerals.

This embodiment, in FIG. 2, a subtracter 32, which was provided with a tank circuit 41 instead of a trap circuit 33, f _SC
And the same effect as in the specific example shown in FIG. 2 can be obtained.

FIG. 8 is a block diagram showing another embodiment of the signal processing circuit of the recording / reproducing apparatus according to the present invention. In FIG. 8, reference numerals 42 and 43 denote switches, and parts corresponding to those in FIG. .

In the embodiment shown in FIG. 1, a dedicated C-shaped comb filter 26 is provided to eliminate the crosstalk component in the reproduced chroma signal C. However, in the embodiment shown in FIG.
This C-shaped comb filter for removing crosstalk components is also used as a C-shaped filter constituting a Y / C separation circuit in a recording system.

That is, in FIG.
2,43 closes to the REC side. The color video signal output from the AGC circuit 2 is supplied to a Y / C separation circuit 3 via a switch 42, where it is separated into a luminance signal Y and a chroma signal C. It is supplied to the circuit 24.

At the time of reproduction, the switches 42 and 43 close to the PB side. The reproduced chroma signal C output from the BPF 27 passes through the switch 42,
The crosstalk component is removed by the C-shaped comb filter supplied to the Y / C separation circuit 3 and constituting the same. The reproduced chroma signal C output from the Y / C separation circuit 3 is supplied to an adder 18 and an output terminal 20.

In this way, the number of comb filters using expensive 1H delay lines can be reduced as compared with the embodiment shown in FIG.

FIG. 9 is a block diagram showing still another embodiment of the signal processing circuit of the recording / reproducing apparatus according to the present invention, wherein 44 is a color level detecting circuit, 45 is a dynamic trap circuit, and corresponds to FIG. The same reference numerals are given to the same parts, and the duplicate description will be omitted.

In the figure, a color level detection circuit 44 detects the level of the chroma signal C output from the C-shaped comb filter 26, and adjusts the amount of attenuation of the dynamic trap circuit 45 according to this level.

In the case of a light color (that is, a portion where the level of the chroma signal is low), the amount of the residual chroma component in the luminance signal is originally small, so that the interference between the residual chroma component and the chroma signal is small. Therefore, in this case, the amount of attenuation of the dynamic trap circuit 45 is reduced so that the definition of the luminance signal is not degraded.

In a dark portion (that is, a portion where the level of the chroma signal is high), the amount of the residual chroma component in the luminance signal is large, so that interference between the residual chroma component and the chroma signal increases.
For this purpose, the amount of attenuation of the dynamic trap circuit 45 is increased.

FIG. 10 shows the dynamic trap circuit 45 in FIG.
Attenuation characteristics according to the chroma signal level of
10 (a) is for a light color (low chroma signal level), FIG. (B) is for a normal dark color, and FIG. (C) is a dark color (high chroma signal level). It is. Even if the level of the luminance component in the chroma band is the same, the lower the level of the chroma signal, the smaller the amount of attenuation of the dynamic trap circuit 45.

FIG. 11 is a block diagram showing a specific example of the color level detection circuit 44 and the dynamic trap circuit 45 in FIG. 9, wherein 35 'is a variable attenuation circuit, 48 is a full-wave rectifier circuit, and 49 is a block diagram.
Is a detection circuit, and 50 is an amplifier, and portions corresponding to the above-mentioned drawings are denoted by the same reference numerals.

In this figure, a dynamic trap circuit 45 has the same configuration as the dynamic trap circuit 17 in FIG. 1, but differs in that an attenuation circuit 35 'of variable attenuation is used.

Hereinafter, the operation of this specific example will be described. The reproduced chroma signal C input from the input terminal 46 is full-wave rectified by the full-wave rectifier circuit 48, detected by the detection circuit 49, and the level of the reproduced chroma signal C is detected. You. The output signal of the detection circuit 49 is an amplifier 50
And is output from the output terminal 47 as a control signal A. The control signal A is input from the input terminal 51 to the dynamic trap circuit 45, and the attenuation of the variable attenuation circuit 35 'is controlled by the control signal A as shown in FIG.

The embodiments of the present invention have been described above, but the present invention is not limited to only these embodiments. For example, according to the present invention, not only a VTR but also a color video signal is Y / C-separated by a comb filter, processed and recorded and reproduced, and a luminance signal and a chroma signal are mixed to generate a color video signal. The present invention can be applied to any recording and reproducing apparatus.

[Effects of the Invention] As described above, according to the present invention, the degradation of the horizontal resolution is minimized, and the degradation of the oblique resolution is not caused.
It is possible to prevent interference between the chroma signal and the residual chroma component in the luminance signal, thereby preventing the occurrence of color flicker and the like.

Furthermore, the number of comb filters using expensive 1H delay lines can be reduced, and the cost of the device can be reduced.

Further, according to the present invention, the amount of attenuation of the dynamic trap circuit is controlled even according to the level of the chroma signal.
The interference between the residual chroma component in the luminance signal and the chroma signal can be effectively prevented without deteriorating the definition of the image.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a signal processing circuit of a recording / reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing a specific example of a dynamic trap circuit in FIG. 1, and FIG. FIG. 4 is a circuit diagram showing a specific circuit configuration of the dynamic trap circuit shown in FIG. 2;
FIG. 5 is a circuit diagram showing a band attenuation filter usable in the embodiment shown in FIG. 2, FIG. 6 is an attenuation characteristic diagram thereof,
FIG. 7 is a block diagram showing another specific example of the dynamic trap circuit in FIG. 1, and FIGS. 8 and 9 are block diagrams showing another embodiment of the signal processing circuit of the recording / reproducing apparatus according to the present invention. FIG. 10 is a characteristic diagram showing the operation of the dynamic trap circuit in FIG. 9, and FIG. 11 is a block diagram showing a specific example of the color level detection circuit and the dynamic trap circuit in FIG. is there. 1 ... color video signal input terminal, 3 ... Y / C separation circuit, 5 ... FM modulation circuit, 7 ... adder, 10 ... rotating magnetic head, 14 ... FM demodulation circuit, 16 ... reproduction Luminance signal output terminal, 17 ... Dynamic trap circuit, 18 ... Adder, 19 ... Reproduced color video signal output terminal, 20 ... Reproduced chroma signal output terminal, 22 ... LPF, 23 ... Frequency converter, 26 ... C comb filter, 27 ... BPF, 42,
43 ... Switch, 44 ... Color level detection circuit, 45 ...
Dynamic trap circuit.

Claims (5)

(57) [Claims] 1. A separating means comprising a comb filter for separating a composite video signal into a luminance signal and a chroma signal, and recording and mixing the luminance signal and the chroma signal to mix a recording signal on a recording medium. Recording processing means for generating;
Reproduction processing means for separating the signal reproduced from the recording medium into the luminance signal and the chroma signal and performing reproduction processing respectively; adding the luminance signal and the chroma signal output from the reproduction processing means to a composite A signal processing circuit of a recording / reproducing apparatus having an adding means for generating a video signal, wherein a chroma band component in the luminance signal is compared with a low-frequency component of the luminance signal output from the reproducing processing means. A signal processing circuit for a recording / reproducing apparatus, comprising: a variable trap circuit that attenuates the signal as the signal amplitude of the band component decreases, and supplies an output luminance signal of the variable trap circuit to the adding unit. 2. An operation according to claim 1, wherein said variable trap circuit is controlled to attenuate a chroma band component in said luminance signal output from said reproduction processing means and to pass said luminance signal without attenuation. A signal processing circuit for a recording / reproducing apparatus, comprising means for arbitrarily selecting. 3. The chroma signal according to claim 1, wherein the chroma signal output from the reproduction processing means is a C signal.
A signal processing circuit of a recording / reproducing apparatus, wherein the signal is supplied to the adding means after a crosstalk component removal process from an adjacent track on the recording medium is performed by a comb filter. 4. The chroma signal according to claim 1, wherein the chroma signal output from the reproduction processing means is subjected to crosstalk component removal processing from an adjacent track on the recording medium by the separation means, and then the addition is performed. A signal processing circuit of the recording / reproducing apparatus, which is supplied to the means. 5. The variable trap according to claim 1, 2, 3 or 4, further comprising a level detecting means for detecting a level of the chroma signal inputted to the adding means, wherein the variable trap is provided in accordance with a detection output of the level detecting means. A signal processing circuit for a recording / reproducing apparatus, wherein the signal processing circuit controls an amount of attenuation of the circuit.