JPH05304683A - Recording and reproducing device for color video signal - Google Patents

Abstract

PURPOSE:To eliminate noise by providing a plurality of horizontal delay devices synthesizing the I/O of one delay device and the output of the other delay device. CONSTITUTION:A synthesizing means 35 consists of a subtracter 35a subtracting the input of the 1st horizontal delay device 31 from the output of the 2nd horizontal delay device 32 and an amplitude limiting device 35b and a 2nd subtracter 35C. The limiting device 35b limits the signal amplitude of an output of the subtracter 35a. The subtracter 35C subtracts an output of the limiting device 35b from the output of a switch SW2 to be inputted to the device 31. When a carrier chrominance signal is outputted from a switch SW2, it is inputted in the synthesizing means 35, subtracting an input of the device 31 from an output of the device 32 to extract the noise component for two horizontal period. The limiting device 35b limits the circulating amount of the noise component, eliminating the noise component through subtraction. Further, a non-linear synthesizing means 27 synthesizes the I/O of the device 31 and the output of the device 32 of a carrier chrominance signal and eliminates the noise component for one horizontal period cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color video signal recording / reproducing apparatus applied to a video tape recorder or the like,
In particular, a color video signal recording / reproducing in which the carrier color signal separated from the color video signal is frequency-converted to a frequency lower than the recording band of the luminance signal and recorded on the recording medium, and the original carrier color signal is reproduced. It relates to the device.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a reproducing system based on a conventional color video signal recording / reproducing apparatus disclosed in Japanese Patent Publication No. 56-9073. Incidentally, a recording system for frequency-converting a carrier color signal separated from a color video signal into a region lower than a recording band of a luminance signal and recording it on a recording medium is also disclosed in the above publication and is well known. The description is omitted.

In FIG. 6, video heads 11a and 11 are shown.
The mixed signal reproduced alternately for each track of the magnetic tape 12 by b is supplied to the high-pass filter 15 via the reproduction preamplifiers 14a and 14b to separate the frequency-modulated luminance signal, while being supplied to the low-pass filter 19. Then, the low-frequency conversion carrier color signal whose phase has been changed (hereinafter also referred to as rotation) as described above is separated.

The reproduction frequency modulated luminance signal taken out from the high-pass filter 15 is supplied to the FM demodulator 17 after the AM component is removed by the limiter 16 and demodulated therein to become a reproduced luminance signal.

On the other hand, the phase rotation reproduction low-pass conversion carrier color signal taken out from the low-pass filter 19 is supplied to a frequency converter 20, where a predetermined center from an APC (Automatic Phase Composer) circuit 21 is supplied. The original color sub-carrier frequency fC (3.5 for NTSC color video signals is converted from the frequency signal to eliminate the time-axis fluctuation component due to tape speed deviation, etc.).
79545 MHz) to the carrier color signal.

The APC circuit 21 is constructed so as to receive a reproduced carrier color signal from a mixer (not shown) as an input signal and output a continuous wave synchronized with the phase of the color burst signal extracted therefrom. There is.

When the reproduced carrier color signal passes through the frequency converter 20, the frequency f output from the APC circuit 21 is output.
Since the original color subcarrier frequency fC is created as the frequency obtained by subtracting the low frequency conversion color subcarrier frequency fS from APC, the phase of the reproduced carrier color signal is inverted. Therefore, the phase rotation direction of 90 ° is reversed.

1 extracted from the frequency converter 20
The phase rotation reproduction carrier color signals having different phases by 90 ° for each H are supplied to the phase shifter 22, where four kinds of waveforms having different phases by 90 ° are created. The four types of signals phase-shifted by 0 °, 90 °, 180 °, and 270 ° respectively from the phase shifter 22 are simultaneously applied to the fixed contacts b1, b2, b3, and b4 of the changeover switch SW2, respectively.

The changeover switch SW2 has its movable contact 1H by the horizontal synchronizing signal separated from the reproduction luminance signal.
The fixed contacts b1 to b4 are sequentially switched and connected one step at a time. Further, the changeover switch SW2 is configured to alternately change the changeover direction from the X direction to the Y direction or from the Y direction to the X direction for each track scanning by a signal synchronized with the rotation of the head. ..

This switching direction is set in the same direction as that of the recorded signal at the time of recording so that the phase shifts by 90 ° together with the phase inversion effect of the frequency converter 20.

Therefore, the reproduction carrier color signal obtained from the movable piece of the changeover switch SW2 is changed over in the X direction by the changeover switch SW2 while the video head 11a is scanning the track A, and the angle is increased by 90 ° every 1H. When the video head 11b is scanning the track B, the changeover switch SW2 is changed over in the Y direction to sequentially advance the phase by 90 ° every 1H. The three line outputs C2, C1 are delayed by being input to and delayed by one horizontal period delay device 31, 32.
C0 is obtained. That is, the output of the switch SW2 is C
2, the output of the one horizontal period delay device 31 is -C2,
The output of the one horizontal period delay device 32 is C0, the output of the inverter 33 as the phase inverting means is C1, and three line outputs C2, C1, C0 of them are input to the non-linear synthesizing means 27.

The non-linear synthesizing means 27 has two maximum value selectors (hereinafter, MAX) for selecting the maximum amplitude value and the minimum amplitude value for the three line outputs C2, C1 and C0, respectively.
27a, 27b, two minimum value selectors (hereinafter referred to as MINs) 27c, 27d, and the two MAs described above.
MIN27 for selecting the minimum value of the outputs of X27a and 27b
e, a MAX 27f that selects the maximum value of the outputs of the two MINs 27c and 27d, and an adder 27g that combines the output from the MIN 27e and the output from the MAX 27f.
It consists of and.

Therefore, the three input line outputs C
2, C1 and CO are the two MAXs 27a and 27b and the two MINs 27c and 27d, and the maximum and minimum values of the respective amplitudes are selected, and then the minimum value (MIN) of the selected maximum amplitudes is selected. The calculated maximum value (MAX) of the minimum amplitude values is input to the adder 27g and combined.
The combined value is MIN {MAX (C0, C1), MAX (C1, C2)} + MAX {MIN (C0, C1), MIN (C1, C2)}, which is the output reproduced luminance signal of the FM demodulator 17. Then, the signal is delayed by one horizontal period and multiplexed for band sharing, and then output from the output terminal 25 as a reproduced color video signal.

In the above synthetic formula, MAX
(P, Q) means comparing two signals P and Q and outputting the larger one, and MIN (P, Q) means comparing two signals P and Q and outputting the smaller one. ing.

FIG. 7 is a waveform diagram showing the operation when a signal having line correlation is present. In this case, the changeover switch SW2
Two signal outputs C0 and C2 separated by two horizontal periods
Is a description of.

First, the signal component of the track A is restored by the phase shifter 22 and becomes equal. As for the crosstalk amount of the track B, the signal after two horizontal periods is delayed by 180 ° in the recording side phase shifter, and further delayed by 180 ° in the reproducing side face shifter 22 to be equal. That is,
The two signal outputs C0 and C2 are equal.

When signals of the above conditions are input to the non-linear synthesizing means 27, MA is generated in the sections T1 and T2 in FIG.
The signal output is selected by X27a, 27b and MIN 27c, 27d.

Since C0 = C2, where it is unclear which one is selected, C0 will be a representative and C2 will be added. In this way, the output of the non-linear synthesizing means 27 becomes C0 + C1 and becomes the sum of the outputs before and after the delay of one horizontal period, and the crosstalk and the noise for each horizontal period can be removed.

[0019]

Since the conventional color video signal recording / reproducing apparatus is configured as described above, it is possible to remove the crosstalk and the noise for each one horizontal period, but two horizontal periods. There is a problem that the noise for each cycle cannot be removed.

The present invention has been made to solve the above-mentioned problems, and in addition to the function of removing the crosstalk and the noise for each horizontal period, noise for every two horizontal periods is also added. It is an object to obtain a color video signal recording / reproducing device that can be removed.

[0021]

According to another aspect of the present invention, there is provided a color video signal recording / reproducing apparatus in which a phase of a carrier color signal whose frequency has been converted into a low frequency band is set in a predetermined direction by about 90 ° every horizontal period. The recording medium is recorded on a recording medium with the phase transition direction changed between adjacent recording tracks, and during reproduction, the phase transition direction at the time of recording is substantially determined from the recorded low frequency conversion carrier color signal. In the opposite direction and 1
A cascade-connected first 1-horizontal period delay device and second 1-horizontal delay device for obtaining and inputting a carrier color signal having an original color sub-carrier frequency whose phase is shifted by about 90 ° for each horizontal period and inputting the carrier color signal The horizontal period delay device and the output of this second one horizontal period delay device are fed back to the input side of the first one horizontal period delay device to extract noise for every two horizontal period periods, and this noise component is transferred as described above. First synthesizing means for subtracting and removing from the color signal, an input of the first one horizontal period delay device, an output of the first one horizontal period delay device, and an output of the second one horizontal period delay device And a second synthesizing means for synthesizing and reproducing.

According to a second aspect of the present invention, there is provided a color video signal recording / reproducing apparatus in which the phase of a carrier color signal whose frequency has been converted into a low frequency band is shifted in a predetermined direction by approximately 90 ° every horizontal period, and the phase thereof is changed. Recording is performed on the recording medium by making the transition directions different from each other between adjacent recording tracks, and at the time of reproduction, in the direction substantially opposite to the phase transition direction at the time of recording from the recorded low-frequency conversion carrier color signal reproduced. Approximately 90 for each horizontal period
A first cascaded first horizontal period delay device and a cascaded second horizontal period delay device for obtaining and inputting a carrier color signal having an original color subcarrier frequency whose phase is shifted by °, and delaying it. The output of the second one horizontal period delay device is fed back to the input side of the first one horizontal period delay device to extract the noise in every two horizontal period periods in opposite phase, and this noise component is converted into the carrier color signal. First combining means for adding and removing, an input of the first one horizontal period delay device, an output of the first one horizontal period delay device and an output of the second one horizontal period delay device are combined. It is provided with a second synthesizing means for reproducing.

In the color video signal recording / reproducing apparatus according to the third aspect of the present invention, the phase of the carrier color signal whose frequency has been converted into the low frequency range is shifted in a predetermined direction by approximately 90 ° for each horizontal period, and the phase thereof is changed. Recording is performed on the recording medium by making the transition directions different from each other between adjacent recording tracks, and at the time of reproduction, in the direction substantially opposite to the phase transition direction at the time of recording from the recorded low-frequency conversion carrier color signal reproduced. Approximately 90 for each horizontal period
Input of a first cascaded first horizontal period delay device and a cascaded second horizontal period delay device for obtaining and inputting a carrier color signal having an original color subcarrier frequency whose phase is shifted by ° By feeding back to the side and extracting noise in every two horizontal feedback cycles in opposite phase, and inputting this noise component, the subtracted values of the outputs of the first and second amplitude limiters having different gains are the carrier color signals. To the input of the first one horizontal period delay device, the output of the first one horizontal period delay device, and the second one. A second synthesizing means for synthesizing and reproducing the output of the horizontal period delay device is provided.

[0024]

In the color video signal recording / reproducing apparatus according to the present invention, the first synthesizing means subtracts the input of the first one horizontal period delay device from the output of the second one horizontal period delay device to obtain 2 A noise component for each horizontal period is extracted, the noise component is subtracted from the input carrier color signal to be removed, and then the carrier color signal is input to the second synthesizing means, whereby crosstalk and one horizontal Noise is removed for each period cycle.

In the color video signal recording / reproducing apparatus according to the second aspect of the invention, in the first synthesizing means, the carrier color signal inputted from the output of the second one horizontal period delay device is subtracted, and every two horizontal period cycles. By extracting the noise component of 1 in the opposite phase, adding the noise component to the carrier color signal to remove it, and then inputting this carrier color signal to the second synthesizing means.
The same effect as the invention of claim 1 is obtained.

In the color video signal recording / reproducing apparatus according to a third aspect of the present invention, in the first synthesizing means, the carrier color signal input from the output of the second one horizontal period delay device is subtracted to generate noise for every two horizontal period cycles. The noise components are removed by extracting the components in the opposite phase, subtracting the outputs of the first and second amplitude limiters having different gains, and adding the subtraction result to the carrier color signal. After that, by inputting this carrier color signal to the second synthesizing means, crosstalk and noise in each horizontal period are removed, and feedback in the burst portion or the non-correlation portion having a high amplitude level is eliminated. It is possible to prevent the circulation of these parts.

[0027]

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the invention of claim 1. The same parts as those of the conventional device shown in FIG. In FIG. 1, 35
Is a first synthesizing means. As shown in FIG. 2, the first synthesizing means 35 includes a first subtractor 35a for subtracting the input of the first horizontal period delay device 31 from the output of the second horizontal period delay device 32, and a first subtractor 35a. From the amplitude limiter 35b that limits the signal amplitude of the output, and the second subtractor 35c that subtracts the output of the amplitude limiter 35b from the output of the switch SW2 to obtain the input of the first one horizontal period delay device 31. It is configured.

Next, the operation will be described. The operation until the carrier color signal is output from the changeover switch SW2 is exactly the same as that of the conventional apparatus shown in FIG.
The operation of the first combining means to which this carrier color signal is input will be described.

First, the noise component for every two horizontal period cycles is extracted by subtracting the input of the first one horizontal period delay device 31 from the output of the second one horizontal period delay device 32. On the other hand, the noise component for every two horizontal period cycles extracted from the carrier color signal having the original color sub-carrier frequency, which is the output of the changeover switch SW2, is subtracted by the amplitude limiter 35b by limiting the amount of circulation. The noise component is removed every two horizontal period cycles.

The carrier color signal from which the noise component has been removed every two horizontal period cycles is the second non-linear synthesizing means 2
By being input to 7, the crosstalk and the noise component for each horizontal period are also removed.

Embodiment 2 FIG. 3 shows an embodiment of the first synthesizing means 35 in the invention of claim 2, in which the output of the changeover switch SW2 is subtracted from the output of the second one horizontal period delay device 32. No. 3 subtractor 35d, an amplitude limiter 35b that limits the signal amplitude of this output, and a first adder 35e that adds the output of the changeover switch SW2 and the output of the amplitude limiter 35b. ..

With this configuration, by subtracting the output of the changeover switch SW2 from the output of the second one horizontal period delay device 32, the noise component for every two horizontal period periods is extracted in the opposite phase. On the other hand, by adding the noise component for each two horizontal period cycles of the opposite phase to the carrier color signal having the original color sub-carrier frequency, which is the output of the changeover switch SW2, by limiting the amount of circulation by the amplitude limiter 35b. The noise component is removed every two horizontal period cycles. The carrier color signal from which the noise component has been removed every two horizontal period cycles is the second non-linear synthesizing means 27.
Is also input to the crosstalk and noise components in each horizontal period are also removed.

Embodiment 3 FIG. 4 shows an embodiment of the first synthesizing means in the invention of claim 3, and the third one for subtracting the output of the changeover switch SW2 from the output of the second one horizontal period delay device 32. Subtractor 3
5d, a first amplitude limiter 35g for limiting the signal amplitude of this output, and a second amplitude limiter 35h having a gain smaller than that of the first amplitude limiter 35g but having the same amplitude limit level.
And a fourth subtractor 35f that subtracts the output of the second amplitude limiter 35h from the output of the first amplitude limiter 35g, and the output of the changeover switch SW2 and the output of the fourth subtractor 35f. And a first adder 35e.

With this configuration, by subtracting the output of the changeover switch SW2 from the output of the second one horizontal period delay device 32, the noise component for every two horizontal period cycles is extracted in the opposite phase. The noise component for every two horizontal period cycles of the opposite phase is
After inputting to the second amplitude limiters 35g and 35h and subtracting the outputs of both the amplitude limiters by the subtractor 35f, the original color sub-carrier which is the output of the subtractor 35f and the output of the changeover switch SW2. By adding the carrier color signal having the frequency, the noise component for every two horizontal period cycles is removed. The carrier color signal from which the noise component has been removed every two horizontal period cycles is input to the non-linear synthesizing means 27, so that the crosstalk and the noise component every one horizontal period period are also removed.

Since the first amplitude limiter 35g, the second amplitude limiter 35h, and the fourth subtractor 35f have the characteristic that they do not output when the input level exceeds a certain level, as shown in FIG. For example, if the amplitude limit level is set to a level lower than the burst level, there is no feedback at the burst portion or the non-correlation portion having a high amplitude level, so that the circulation of these portions can be prevented.

In the above embodiment, the second synthesizing means 2
Although 7 is a non-linear one, it is not limited to this as long as it is a synthesizing means having a frequency characteristic showing a comb-shaped characteristic. For example, C0
A linear one such as + 2C1 + C2 may be used, or another non-linear combining means may be used.

[0038]

As described above, the first or second aspect of the present invention is provided.
According to the invention, the carrier color signal is input to the first synthesizing means, noise in every two horizontal period cycles is extracted in the positive or negative phase, and this noise component is subtracted from the input carrier color signal or Since noise components are added to the carrier color signal for every two horizontal period cycles and then the carrier color signal is input to the second synthesizing means, crosstalk and one horizontal period cycle are performed. In addition to removing noise, it is possible to remove noise every two horizontal period cycles, and the noise removal effect is improved.

According to the third aspect of the invention, the carrier color signal is input to the first synthesizing means, and the noise obtained by extracting the noise in every two horizontal period cycles in the opposite phase as in the second aspect of the invention. The components are input to the first and second amplitude limiters having different gains, the subtracted values of the outputs of the both amplitude limiters are added to the input carrier color signal, and then the second combination means is provided. Since it is configured to be input, it has the same noise removal effect as in claims 1 and 2, and if the amplitude limit level is set to a level lower than the burst level, for example, in the burst portion or the non-correlation portion with a high amplitude level, There is no return, and it is possible to prevent the patrol of these parts.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a color video signal recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing an embodiment of a first synthesizing means in the invention of claim 1;

FIG. 3 is a block diagram showing an embodiment of a first synthesizing means in the invention of claim 2;

FIG. 4 is a block diagram showing an embodiment of a first synthesizing means according to the invention of claim 3;

FIG. 5 is a diagram for explaining the operation of each part of the first combining means shown in FIG.

FIG. 6 is a block diagram showing a conventional color video signal recording / reproducing apparatus.

FIG. 7 is a waveform response diagram for explaining the operation of the conventional device.

[Explanation of symbols]

 12 magnetic tape (recording medium) 27 second synthesizing means 31 first one horizontal period delay device 32 second one horizontal period delay device 35 first synthesizing means 35g first amplitude limiter 35h second amplitude limiting device vessel

Claims (3)

[Claims] 1. A color video signal recording / reproducing apparatus for frequency-converting a carrier color signal separated from a color video signal into a low frequency band, recording it on a recording medium, and reproducing the original carrier color signal in the low frequency band. The phase of the carrier color signal frequency-converted to
The phase shifts in a predetermined direction by about 90 ° for each horizontal period,
And, the phase transition direction is made different from each other between adjacent recording tracks and recorded on the recording medium, and at the time of reproduction, the phase transition direction at the time of recording is substantially determined from the recorded low frequency conversion carrier color signal. 90 in the opposite direction and every horizontal period
A first cascaded first horizontal period delay device and a cascaded second horizontal period delay device for obtaining and inputting a carrier color signal having an original color subcarrier frequency whose phase is shifted by °, and delaying it. The output of the second 1-horizontal period delay device is fed back to the input side of the 1st 1-horizontal period delay device to extract noise for every 2 horizontal period periods, and this noise component is subtracted from the carrier color signal. The first synthesizing means for removing, the input of the first one horizontal period delay device, the output of the first one horizontal period delay device and the output of the second one horizontal period delay device are synthesized and reproduced. A color video signal recording / reproducing apparatus provided with a second synthesizing means. 2. A color video signal recording / reproducing apparatus for frequency-converting a carrier color signal separated from a color video signal into a low frequency band, recording it on a recording medium, and reproducing the original carrier color signal in the low frequency band. The phase of the carrier color signal frequency-converted to
The phase shifts in a predetermined direction by about 90 ° for each horizontal period,
And, the phase transition direction is made different from each other between adjacent recording tracks and recorded on the recording medium, and at the time of reproduction, the phase transition direction at the time of recording is substantially determined from the recorded low frequency conversion carrier color signal. 90 in the opposite direction and every horizontal period
A first horizontal period delay device and a second horizontal period delay device which are cascaded to obtain a carrier color signal having an original color subcarrier frequency whose phase is shifted by °, and input and delay the carrier color signal; The output of the second 1-horizontal period delay device is fed back to the input side of the 1st 1-horizontal period delay device to extract noise in every 2 horizontal period periods in anti-phase, and this noise component is added to the carrier color signal. And removing the first first horizontal period delay device, the input of the first one horizontal period delay device, the output of the first one horizontal period delay device, and the output of the second one horizontal period delay device. A color video signal recording / reproducing apparatus provided with a second synthesizing unit for reproducing by reproducing. 3. A color video signal recording / reproducing apparatus for frequency-converting a carrier color signal separated from a color video signal into a low frequency band, recording it on a recording medium, and reproducing the original carrier color signal in the low frequency band. The phase of the carrier color signal frequency-converted to
The phase shifts in a predetermined direction by about 90 ° for each horizontal period,
And, the phase transition direction is made different from each other between adjacent recording tracks and recorded on the recording medium, and at the time of reproduction, the phase transition direction at the time of recording is substantially determined from the recorded low frequency conversion carrier color signal. 90 in the opposite direction and every horizontal period
A first cascaded first horizontal period delay device and a second cascaded horizontal period delay device for obtaining and inputting and delaying a carrier color signal having an original color sub-carrier frequency whose phase is shifted by .degree. The output of the second 1-horizontal period delay device is fed back to the input side of the 1st 1-horizontal period delay device, noise is extracted in anti-phase every two horizontal period periods, and the gain of inputting this noise component is changed. First combining means for adding the subtracted values of the outputs of the first and second amplitude limiters to the carrier color signal to remove the noise component from the carrier color signal;
Of the first horizontal period delay device, the output of the first one horizontal period delay device, and the output of the second one horizontal period delay device are combined to reproduce the color video signal. Recording / playback device.