JPH0370438B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a video signal reproducing device, in which at least one of a reproduced luminance signal and a reproduced carrier color signal is reproduced from a magnetic recording medium on which a luminance signal and a carrier color signal are multiplexed and recorded. The present invention relates to a video signal reproducing device that restores an original video signal with reduced noise by de-emphasizing one signal to the frequency characteristics in the time axis direction. (Prior Art) FIG. 1 shows a schematic block system diagram of a video circuit system of a general video signal recording and reproducing apparatus. In the same figure,
The video signal to be recorded (especially the luminance signal) that enters the input terminal 1 is supplied to the pre-emphasis circuit 2, where the high frequency components are amplified.
The signal is supplied to the FM modulation circuit 3, where it undergoes frequency modulation such that the sync chip level and white peak level of the video signal each become a predetermined frequency. The FM video signal (modulated wave) taken out from the FM modulation circuit 3 is supplied to the magnetic head 4 via a recording amplifier (not shown), etc., and thereby recorded on the magnetic tape 5. On the other hand, during playback, the already recorded FM video signal on the magnetic tape 5 is played back by the magnetic head 6, passed through a playback amplifier (not shown), etc., and then sent to the FM demodulation circuit 7.
After being FM demodulated, it is supplied to the de-emphasis circuit 8. The de-emphasis circuit 8 is provided to attenuate the high frequency components amplified by the pre-emphasis circuit 2 and return them to their original state, and the output reproduced video signal is taken out from the output terminal 9. As is well known, the S/N (signal-to-noise ratio) of an FM video signal deteriorates as the frequency component increases, so the pre-emphasis circuit 2 increases the level of the high frequency component to increase the degree of modulation for that frequency. Therefore, the S/N of high frequencies can be improved. Conventionally, the pre-emphasis circuit 2 is configured with a filter using a CR shown in FIG.
The de-emphasis circuit 8 is configured by a filter using a CR shown in _FIG .
As shown in Figure B, the frequency _{is 1} for the input video signal.
Attempts have been made to provide characteristics that suppress the above-mentioned high frequency components more than the low frequency components. Here, the pre-emphasis characteristics shown in Fig. 2B and the pre-emphasis characteristics shown in Fig. 3B
The de-emphasis characteristics shown in (a) and (b) are mutually complementary characteristics. (Problems to be solved by the invention) By the way, the pre-emphasis circuit 2 of the conventional device
The de-emphasis circuit 8 generates a plurality of signals (on the left side of the P point) on the same horizontal scanning line that are slightly delayed positionally, as shown by F and E, with respect to the signal at the P point on the screen 10 shown in FIG. If a backward type transversal filter is used, the same horizontal scan signal displayed to the right of point P as shown by B and E in Figure 4. It subtracts or adds multiple signals that advance positionally little by little along the line, and pre-emphasis or de-emphasis is performed between the signals within one horizontal scanning line (for convenience, this is referred to as "horizontal emphasis"). ). Therefore, it was only possible to reduce high frequency noise in the horizontal direction of the screen. Furthermore, since the pre-emphasis circuit 2 relatively enhances high frequency components, for example, when pre-emphasizing a waveform as shown in FIG. 5A, the output signal waveform will overshoot as shown in FIG. 5B. In the rising portion from black to white where overshoot occurs, the instantaneous frequency of the FM signal output from the FM modulation circuit 3 becomes extremely high, and when this FM signal is recorded and reproduced on the magnetic tape 5, the above-mentioned overshoot occurs. When the UT exceeds a certain level, it deviates from the slice area of the limiter at the input stage of the FM demodulation circuit 7, causing a signal missing portion at the limiter output, which is FM demodulated as a low frequency in the FM demodulation circuit 7. As a result, it is known that a so-called inversion phenomenon occurs in which the FM demodulated output drops to black. For this reason, conventionally a circuit was provided at the input stage of the FM modulation circuit 3 to prevent the amplitude at the tip of the overshoot from exceeding a predetermined value, but since the conventional method was horizontal emphasis, the noise reduction effect was This is not sufficient, and in order to improve the S/N ratio, it is necessary to apply deep clipping, which poses a problem in that there is some kind of image quality deterioration at the rising and falling edges of the waveform. On the other hand, with respect to reproduced carrier color signals, noise has been conventionally reduced using line correlation, but this conventional circuit reduces noise as well as line correlation for reproduced carrier color signals that have no line correlation. Since signal components with no color are also subtracted from the input reproduced carrier color signal, there is a problem in that the vertical resolution deteriorates. Therefore, the present invention de-emphasizes the frequency characteristics in the time axis direction of at least one of the reproduced luminance signal and the carrier chrominance signal, thereby eliminating noise in the luminance signal and the carrier chrominance signal. It is an object of the present invention to provide a video signal reproducing device that solves at least one of the respective problems regarding reduction. (Means for Solving the Problems) The present invention provides a means for solving problems in the time axis direction with respect to at least one of a reproduced luminance signal and a reproduced carrier color signal in the original signal form extracted from a reproduced signal processing circuit. The de-emphasis circuit is provided with a de-emphasis circuit that provides a characteristic in which the level of the high-frequency component of the frequency is relatively attenuated compared to the reduced component, regardless of or in relation to the amplitude of the input signal. This will be explained with reference to Figure 6 and the following drawings. (Embodiment) FIG. 6 shows a block system diagram of a first embodiment of the apparatus of the present invention. In the figure, the standard television system (NTSC system or PAL system) input to input terminal 11
The color video signal is supplied to a low-pass filter 12 to separate the luminance signal, and is supplied to the bandpass filter 13 to separate the carrier color signal. The luminance signal is supplied to a pre-emphasis circuit 14, which will be described later and forms the main part of this embodiment, where the high-frequency component of the frequency in the time axis direction (hereinafter referred to as "temporal frequency") is compared to the low-frequency component. The level is increased relatively regardless of or depending on the amplitude of the input signal. The luminance signal taken out from the pre-emphasis circuit 14 is sent to the recording luminance signal processing circuit 1.
5, where e.g. frequency modulation (FM)
etc. are subjected to predetermined signal processing. On the other hand, the conveyance color signal is transmitted to the recording conveyance color signal processing circuit 1.
For example, the frequency is converted so that the frequency band does not overlap with the frequency band lower than the frequency band of the FM luminance signal, and during the frequency conversion, the signal is supplied to The color subcarrier undergoes phase shift processing. Recording luminance signal processing circuit 15 and recording conveyance color signal processing circuit 16
The luminance signal and the carrier color signal, which are respectively subjected to the above-mentioned predetermined signal processing and converted into a predetermined signal form and taken out, are supplied to the recording amplifier 17, where they are mixed and amplified, and then sent to the recording rotary head. The information is recorded on the magnetic tape 19 by 18. On the other hand, during reproduction, the already recorded signal on the magnetic tape 19 is reproduced by the rotary reproduction head 20, and the reproduced signal is supplied to the high-pass filter 22 and the low-pass filter 23 through the preamplifier 21. For example, the FM luminance signal is separated by the high-pass filter 22 and demodulated into the original band luminance signal by the reproduced luminance signal processing circuit 24. On the other hand, low-pass filter 2
For example, the carrier color signal that has been low-band converted and recorded by 3 is separated from the reproduced signal, and this carrier color signal is supplied to the reproduced carrier color signal processing circuit 25, where the original signal form (bandwidth, phase, etc.) to become a reproduced transport color signal. The above-mentioned reproduced luminance signal is supplied to a de-emphasis circuit 26, which will be described later, which is a main part of this embodiment, and is given a time-frequency versus level characteristic complementary to that of the pre-emphasis circuit 14. Restored to waveform. The reproduced luminance signal output from the de-emphasis circuit 26 is mixed with the reproduced carrier color signal from the reproduced carrier color signal processing circuit 25. As a result, a reproduced color video signal is output from the mixing circuit 27 to the output terminal 28 in which noise components that cannot be removed by intra-screen emphasis (horizontal emphasis, vertical emphasis) are also reduced. In this embodiment, since the time-frequency versus level characteristic is de-emphasized by the de-emphasis circuit 26, the S/N ratio of the reproduced luminance signal can be improved, and the time-frequency versus level characteristic deteriorated by the de-emphasis circuit 26 can be improved. Since the level characteristics are emphasized and recorded by the pre-emphasis circuit 14 provided in the recording system in advance, the S/N ratio is improved from the de-emphasis circuit 26, and the reproduced luminance is maintained without deterioration of the time-frequency vs. level characteristics. A signal is extracted. In addition, as described later, the pre-emphasis circuit 1
4 and the de-emphasis circuit 26 have non-linear characteristics such that the time-frequency versus level characteristics change according to the amplitude of the input signal, when pre-emphasis and de-emphasis are applied to the above-mentioned time frequency, the still image Or, there is no problem with slow-moving videos, but overshoot occurs when fast-moving videos or screen changes occur, and as with horizontal and vertical emphasis, the image quality is affected by the information discarded in white clips and dark clips. However, since the amount of information that is discarded can be reduced, it is possible to improve the deterioration of image quality after edges such as at the time of screen switching. It will also be compatible with current VTRs. Next, a second embodiment of the device of the present invention will be described. FIG. 7 shows a block system diagram of a second embodiment of the device of the present invention. In the figure, the same components as those in FIG. 6 are denoted by the same reference numerals, and the explanation thereof will be omitted. In the first embodiment described above, a pre-emphasis circuit 11 and a de-emphasis circuit 26 were provided in the recording and reproducing path of the luminance signal, whereas in this embodiment, a pre-emphasis circuit 29 and a de-emphasis circuit 30 were provided in the recording and reproducing path of the carrier color signal. It is characterized by the provision of . That is, the pre-emphasis circuit 29 compares the high-frequency component of the time frequency of the carrier color signal with the low-frequency component, and relatively increases the level regardless of the amplitude of the input signal or in accordance with the amplitude, and outputs the signal to the recording carrier color signal processing circuit 16. supply to. In addition, the de-emphasis circuit 3
0 imparts a time frequency versus level characteristic complementary to that of the pre-emphasis circuit 29 to the reproduced carrier color signal taken out from the reproduced carrier color signal processing circuit 25 and outputs it. As a result, according to the present embodiment, the S/N ratio improvement effect similar to the S/N ratio improvement effect of the luminance signal in the first embodiment is achieved.
An N-ratio improvement effect is obtained for the carrier color signal. Next, embodiments of the pre-emphasis circuit 14 and the de-emphasis circuit 26 will be described. FIG. 8 shows a block diagram of a first embodiment of the pre-emphasis circuit 14. In the figure, the luminance signal input to the input terminal 32 is transmitted to the adder circuit 33 and the subtracter circuit 3.
4, respectively. The luminance signal taken out from the adder circuit 33 is supplied to a delay circuit 35. The delay circuit 35 is configured so that the input luminance signal is NTSC format or PAL format.
Regardless of the method, if the luminance signal is separated from the color video signal, the 2m field or (2m+1)
Field +0.5H or (2m+1) Field -
It has a delay time of 0.5H (where m is 0,
1, 2, . . . , H indicates one horizontal scanning period. same as below). This means that one field of the luminance signal of the NTSC color video signal is 262.5H (in the PAL format, the luminance signal is 262.5H).
312.5H), and for odd field delays
Since the phase is shifted by 0.5H, the delay time is set to be a period that is a natural number multiple of one field or a period that is very close to this, and a period that is a natural number multiple of the horizontal scanning period. The delayed luminance signal taken out from the delay circuit 35 is sent to a coefficient circuit 36 which multiplies it by a coefficient O ₁ (for example, 0.76).
is attenuated by and then supplied to the adder circuit 33,
Here, after being added and combined with the luminance signal from the input terminal 32, it is again supplied to the delay circuit 35. Further, the output delayed luminance signal of the delay circuit 35 has a coefficient O ₂ (for example,
0.14) through the subtraction circuit 3 through the coefficient circuit 37
4. The subtraction circuit 34 performs an operation of subtracting the luminance information from the coefficient circuit 37 from the input luminance signal from the input terminal 32 for a period that is a natural number multiple of about 1 field, so that the high frequency component of the time frequency of the input luminance signal is The output terminal 38 outputs a luminance signal (luminance signal to be pre-emphasized) to which a pre-emphasis characteristic whose level is relatively enhanced compared to the low-frequency component is given.
Output to. FIG. 9 shows a block diagram of a first embodiment of the de-emphasis circuit 26. In the figure, a reproduced luminance signal that has been converted into its original signal form is input to an input terminal 39. However, this reproduced luminance signal is given the pre-emphasis characteristic. This reproduced luminance signal is supplied to a delay circuit 42 through an adder circuit 40, and is also supplied to an adder circuit 41. _{The delay circuit 42 is selected to have the same delay time as the delay circuit 35, and supplies the delayed reproduced luminance signal to the adder circuit 10 through a coefficient circuit 43 that multiplies it by a coefficient N 1 (} for example, 0.87).
0.18) through a coefficient circuit 44
Supply to 1. The output signal of the adder circuit 40 is supplied to a delay circuit 42, and the output signal of the adder circuit 41 is output to an output terminal 45. Here, the output signal of the output terminal 45 has a characteristic in which the high frequency component of the time frequency of the input reproduced luminance signal is relatively attenuated in level compared to the low frequency component, and the pre-emphasis circuit shown in FIG. This is a reproduced luminance signal (de-emphasized reproduced luminance signal) to which a characteristic complementary to the characteristic is given, and is a reproduced luminance signal restored to the same waveform as the input luminance signal of the input terminal 32 of the pre-emphasis circuit. The pre-emphasis circuit 14 shown in FIG.
As is clear from comparing the de-emphasis circuit 26 shown in the figure, both circuits have substantially the same circuit configuration, and the coefficients O ₁ , O ₂ , N ₁ , and N ₂ of the coefficient circuits 36, 37, 43, and 44 are Differences and subtraction circuit 34
The only difference is that the circuit corresponding to the de-emphasis circuit 26 is an adder circuit. Then,
In the following description, illustration of the de-emphasis circuit 26 or 30 will be omitted as necessary. FIG. 10 shows a block diagram of a second embodiment of the pre-emphasis circuit 14. In the figure, the same components as those in FIG. 8 are designated by the same reference numerals, and their explanations will be omitted. A part of the luminance signal supplied from the adder circuit 33 to the delay circuit 35 is branched and supplied to the coefficient circuit 47, and a coefficient P ₂ (for example, 0.14) is applied to this input signal.
is multiplied by , and supplied to the subtraction circuit 34. Further, the coefficient circuit 46 applies a coefficient to the output delayed luminance signal of the delay circuit 35.
It is multiplied by P ₁ (for example, 0.76) and output to the adder circuit 33. This embodiment differs from the first embodiment of the pre-emphasis circuit 14 shown in FIG. 8 in that the delay circuit 35 is not provided in the signal path from the input terminal 32 through the subtraction circuit 34 to the output terminal 38. The de-emphasis circuit shown in FIG. 10, which has characteristics complementary to the pre-emphasis circuit, has the same configuration as that in FIG.
For example, the coefficients of the coefficient circuit corresponding to 6 and 47 are
0.87 and 0.18, and the only difference is that the circuit corresponding to the subtraction circuit 34 is an addition circuit, so illustration is omitted. Next, a third embodiment of the pre-emphasis circuit 14 will be described with reference to FIG. In FIG. 11, the same components as those in FIG. 10 are designated by the same reference numerals, and their explanations will be omitted. In FIG. 11, coefficient circuit 4
8 is a circuit that multiplies the output signal of the adder circuit 33 by a coefficient K ₂ (for example, about 0.24) and outputs the result to the subtractor circuit 34, and corresponds to the coefficient circuit 47 in FIG. The luminance signal extracted from the subtraction circuit 34 is supplied to a non-linear circuit 49. The nonlinear circuit 49 is, for example, an amplitude limiter that limits the amplitude of an input signal to a constant value, and is configured so that input signals with an amplitude smaller than this constant value are passed through and output as they are without amplitude limiting. ing. The signal taken out from the non-linear circuit 49 is converted into a coefficient by a coefficient circuit 50.
After being multiplied by K ₃ (for example, about 1.3), the addition circuit 51
Here, it is added and combined with the input luminance signal and output to the output terminal 52. As a result, the output terminal 52 has a non-linear pre-emphasis characteristic in which the high-frequency component of the time frequency of the input luminance signal is relatively enhanced in level according to the amplitude of the input signal compared to the low-frequency component. The applied luminance signal is applied. That is, this embodiment is the same as the first and second embodiments of the pre-emphasis circuit 14 shown in FIGS. 8 and 10 in that it is a feed-forward type pre-emphasis circuit, but this embodiment has the following features: The difference is that the first and second embodiments have linear pre-emphasis characteristics, whereas they have non-linear pre-emphasis characteristics. The configuration of the de-emphasis circuit 26 shown in FIG. 11, which has characteristics complementary to the pre-emphasis circuit 14, is such that the coefficients of the coefficient circuits corresponding to the coefficient circuits 48 and 50 are, for example, 0.13 and 0.57; For example, the coefficient of the coefficient circuit is 0.87
The circuit configuration is the same as that shown in FIG. 11 except that a subtraction circuit for subtracting the output signal of the coefficient circuit from the input reproduced luminance signal is used instead of the addition circuit 51. The above are examples of the pre-emphasis circuit 14 and the de-emphasis circuit 26 provided in the transmission path of the luminance signal.Next, we will discuss each example of the pre-emphasis circuit 29 and the de-emphasis circuit 30 provided in the transmission path of the carrier color signal. explain. FIG. 12 shows a block diagram of a first embodiment of the pre-emphasis circuit 29. In the figure, input terminal 55
The incoming carrier color signal is supplied to a delay circuit 58 through an arithmetic circuit 56, and is also supplied to a subtraction circuit 57. Here, if the input carrier color signal is a carrier color signal separated from the NTSC color video signal, its color subcarrier frequency is, as is well known, 227.5 times the horizontal scanning frequency, and due to the fraction of 0.5. The color subcarrier has a phase difference of 0.5 period, or 180°, at the beginning and end of 1H. Also 1
The field is 262.5H, and the phase of the carrier color signal with an odd field time difference from each other is 0.5H
It will shift. Therefore, the two signals calculated by the calculation circuit 56 (also 64, which will be described later) need to be in phase and added without any phase shift. Therefore, the delay time of the delay circuit 58 and the calculation circuit 5
The relationship between whether the operation of 6 is addition or subtraction is as follows. First, when the delay time is 4 m field (=2 m frame), the 4 m field is 1050 mH, which is an even number H, so the arithmetic circuit 56 is set to perform an addition operation. Next, when the delay time is (4m + 1) field - 0.5H or (4m + 3) field + 0.5H,
In either case, the delay time is an even number multiple of H, so the arithmetic circuit 56 is set to perform the addition operation. On the other hand, the delay time of the delay circuit 58 is (4 m
+1) If you select one of the delay times of field +0.5H, (4m+2) field (=2m+1 frame), and (4m+3) field -0.5H, the delay time will be an odd multiple of H.
Arithmetic circuit 56 is set to perform a subtraction operation. The carrier color signal taken out from the delay circuit 58 whose delay time has been selected from among the above ~ is multiplied by the same coefficient O ₁ as the coefficient circuit 36 in the coefficient circuit 59, and then the phase adjuster 60
is supplied to the arithmetic circuit 56, where it is added or subtracted as described above. The phase adjuster 60 is an unnecessary circuit if the delay time of - out of - is accurately obtained by the delay circuit 58. However, since the delay time actually obtained by the delay circuit 58 is not an accurate predetermined delay time and has an error, if it is supplied to the arithmetic circuit 56 with this error (without performing phase adjustment). ,
Since the coefficient O ₁ operates equivalently as if it were multiplied by a coefficient having a value different from the predetermined value, the desired pre-emphasis characteristic cannot be obtained. Therefore, the phase adjuster 60 adjusts the phase of the output signal of the coefficient circuit 59 to a period that is a natural number multiple of one field or a period close to that, and a period that is a natural number multiple of H.
By adjusting the phase to be exactly the same as the phase of the delayed carrier color signal, the desired pre-emphasis characteristic can be obtained. On the other hand, the output delayed carrier color signal of the delay circuit 58 is
The signal is supplied to a coefficient circuit 61, where it is given the same coefficient as the coefficient _O2 , and then supplied to a subtraction circuit 57. The subtracting circuit 57 performs a subtraction operation of subtracting the output carrier color signal of the coefficient circuit 61 from the input carrier color signal of the input terminal 55, and outputs the obtained signal to the output terminal 62 as a pre-emphasized carrier color signal. This output signal is a carrier color signal to which a pre-emphasis characteristic is added in which the level of the high-frequency component of the time frequency of the input carrier color signal is relatively enhanced compared to the low-frequency component. It is output as a pre-emphasis carrier color signal). FIG. 13 shows a block diagram of a first embodiment of the de-emphasis circuit 30. In the same figure, a reproduced carrier color signal that has been returned to the original band is input to an input terminal 63, and this reproduced carrier color signal is input to the subtraction circuit 63.
4 and an adder circuit 69, respectively. The output signal of the arithmetic circuit 64 is fed back to the arithmetic circuit 64 through a delay circuit 65 having the same delay time as the delay circuit 58, a coefficient circuit 66, and a phase adjuster 67, and is added via the coefficient circuit 68. It is supplied to circuit 69. Like the phase adjuster 60, the phase adjuster 67 is a circuit that performs phase adjustment to obtain an accurate delayed output. Further, the coefficient N ₁ of the coefficient circuit 66 is, for example, 0.87, and the coefficient N ₂ of the coefficient circuit 68 is, for example, 0.18.
It is. Addition circuit 69 adds the reproduced carrier color signal from input terminal 63 and the reproduced carrier color signal from coefficient circuit 68 and outputs the resulting signal to output terminal 70 . This output signal is a reproduced carrier color signal (de-emphasized reproduced carrier color signal) to which a de-emphasis characteristic is applied, in which the level of the high-frequency time-frequency components of the input reproduced carrier color signal is relatively attenuated compared to the low-frequency components. be. Further, this de-emphasis characteristic is exactly complementary to the pre-emphasis characteristic in which the level is attenuated by the amount of level enhancement of the pre-emphasis characteristic. Next, a second embodiment of the pre-emphasis circuit 29 will be described. FIG. 14 shows a block diagram of the second embodiment of the pre-emphasis circuit 29. In the figure, the same components as those in FIG. 12 are denoted by the same reference numerals, and the explanation thereof will be omitted. The coefficient circuit 71 supplies a signal obtained by multiplying the output delayed carrier color signal of the delay circuit 58 by a coefficient P ₁ to the arithmetic circuit 56 through the phase adjuster 60 . Further, the coefficient circuit 72 is supplied with a branched part of the carrier color signal supplied from the arithmetic circuit 56 to the delay circuit 58 , multiplies this input signal by a coefficient P ₂ and supplies the multiplied signal to the subtraction circuit 57 . As a result, a pre-emphasized carrier color signal similar to that shown in FIG. 12 is extracted from the subtraction circuit 57. In this example, the 12th
Compared to the first embodiment of the pre-emphasis circuit 29 shown in the figure, a delay circuit 58 is provided in the signal path from the input terminal 55 to the output terminal 62 via the arithmetic circuit 56, coefficient circuit 72, and subtraction circuit 57. do not have. The de-emphasis circuit shown in FIG. 14, which has characteristics complementary to the pre-emphasis circuit, has the same configuration as that in FIG.
For example, the coefficients of the coefficient circuit corresponding to 1 and 72 are
0.87 and 0.18, and the only difference is that the circuit corresponding to the subtraction circuit 57 is an addition circuit, so illustration thereof is omitted. Next, a third embodiment of the pre-emphasis circuit 29 will be described with reference to FIG. 15. In Figure 15,
Components that are the same as those in FIG. 14 are given the same reference numerals, and their explanations will be omitted. In FIG. 15, the coefficient circuit 73 calculates a coefficient K ₂ for the output signal of the arithmetic circuit 56.
(for example, about 0.24) and outputs the result to the subtraction circuit 57, which corresponds to the coefficient circuit 72 in FIG.
The carrier color signal taken out from the subtraction circuit 57 is supplied to a non-linear circuit 74. Like the non-linear circuit 49, the non-linear circuit 74 is, for example, an amplitude limiter that limits the amplitude of an input signal to a constant value, and for input signals whose amplitude is smaller than this constant value, the amplitude is not limited. It is configured to pass through and output as is. The signal taken out from the non-linear circuit 74 is multiplied by a coefficient K ₃ (for example, about 1.3) by a coefficient circuit 75 and then supplied to an adder 76 where it is added and synthesized with the input carrier color signal and sent to an output terminal 77. Output to. As a result, the output terminal 77 has a non-linear pre-emphasis characteristic in which the high-frequency components of the temporal frequency of the input carrier color signal are relatively enhanced in level according to the amplitude of the input signal compared to the low-frequency components. A carrier color signal to which is given is given. That is, this embodiment is the same as the first and second embodiments of the pre-emphasis circuit 29 shown in FIGS. 12 and 14 in that it is a feed-forward type pre-emphasis circuit, but this embodiment has the following features: The difference is that the first and second embodiments have linear pre-emphasis characteristics, whereas they have non-linear pre-emphasis characteristics. The configuration of the de-emphasis circuit 30 shown in FIG. 15, which exhibits complementary characteristics to the pre-emphasis circuit 29, is such that the coefficients of the coefficient circuits corresponding to the coefficient circuits 73 and 75 are, for example, 0.13 and 0.57; The coefficients of the coefficient circuits are also set to different values, and the circuit configuration is the same as that shown in FIG. 14, except that the addition circuit 76 is replaced by a subtraction circuit that subtracts the output signal of the coefficient circuit from the input reproduced carrier color signal. . The above-described embodiments of the pre-emphasis circuits 14, 29 and the de-emphasis circuits 26, 30 are all of the feed-forward type.Next, the pre-emphasis circuit and the de-emphasis circuit of the feedback type will be explained. FIG. 16 shows a block system diagram of an embodiment in which the pre-emphasis circuit 29 and the de-emphasis circuit 30 each share the same circuit. First, to explain the operation during playback, during playback, switches 81 and 8
3, 93 and 94 are respectively switched and connected to the contact P side. As a result, the reproduced carrier color signal that has entered the input terminal 80 is supplied to the arithmetic circuit 84 through the switch 81, the arithmetic circuit 84, the delay circuit 85, the coefficient circuit 86, and the phase adjuster 87, where the The signal is subtracted from or added to the reproduced carrier color signal after a period approximately equal to a natural number times one field and after a period equal to a natural number times H. The output signal of the arithmetic circuit 84 is supplied to a delay circuit 85, and is also supplied to an arithmetic circuit 89 through a coefficient circuit 88, where it is subtracted from the reproduced carrier color signal from the switch 81, and then further processed by a non-linear circuit 90 and a coefficient. It is supplied to the arithmetic circuit 92 through the circuit 91, where the switch 8
1 is subtracted from the reproduced carrier color signal. Therefore,
A reproduced carrier color signal to which a non-linear de-emphasis characteristic has been added is taken out from the subtraction circuit 92 and outputted to an output terminal 95 through a switch 94.
According to this embodiment, by including the non-linear circuit, it is possible to reduce the rate at which the de-emphasis circuit cannot completely restore the original waveform (for example, if the gain of the differential amplifier 82 is G,
(The deviation is only 1/G). On the other hand, during recording, switches 81, 83, 93,
and 94 are respectively connected to the contact R side. As a result, the carrier color signal input to the input terminal 80 is sent to the arithmetic circuit 84 through the switch 81, the differential amplifier 82, the switch 83, the arithmetic circuit 84, the delay circuit 85, the coefficient circuit 86, and the phase adjuster 87, respectively. Supplied. The relationship between the delay time of the delay circuit 85 and the subtraction operation of the arithmetic circuit 84 is the same as the delay time of the delay circuit 58 and the addition/subtraction operation of the arithmetic circuit 56. The carrier color signal taken out from the arithmetic circuit 64 is supplied to a delay circuit 85, and is also supplied to a subtraction circuit 89 through coefficient circuits 88, where it is subtracted from the carrier color signal from the switch 83, and is then inactivated. It is supplied to a linear circuit 90. The non-linear circuit 90 has the same configuration as the non-linear circuits 49 and 74, and the output carrier color signal of the subtraction circuit 89 is extracted with the amplitude of a portion larger than a constant value being limited in amplitude, and is further output through the coefficient circuit 91 to the subtraction circuit. 9
2, where it is subtracted from the carrier color signal from switch 83. This circuit obtains a pre-emphasis characteristic that is the opposite of the de-emphasis circuit during playback by placing it in the feedback loop. Therefore, the switch 9 from the differential amplifier 82
4 to the output terminal 95 becomes a non-linear pre-emphasized carrier color signal as in FIG. The coefficients L ₁ , L ₂ and L ₃ of the coefficient circuits 86, 88 and 94 are, for example, 0.87,
Selected as 0.13 and 0.57. The relationship between the circuit formats of the pre-emphasis circuits and de-emphasis circuits of the embodiments of the apparatus of the present invention described above and the drawing numbers showing the embodiments corresponding to the formats is summarized as shown in the following table.

[Table] Note that although illustrations of the pre-emphasis circuit and de-emphasis circuit indicated by parts a to c in the above table are omitted, these circuits are also included in the device of the present invention. For example, the pre-emphasis circuit and de-emphasis circuit of c are constructed from the circuit shown in FIG.
and the subtraction circuit 92 are deleted, and the output terminal of the coefficient circuit 89 is connected to the contact R of the switch 93 and the contact P of the switch 94 (coefficients L ₁ , L ₂
be the same as N ₁ and N ₂ in FIG. 13). In addition, the pre-emphasis circuit and de-emphasis circuit in column b are the first
The phase adjuster 87 is removed from FIG. 6, the delay time of the delay circuit 85 is set to be the same as that of the delay circuit 35, the arithmetic circuit 84 is replaced with an adder circuit, and the luminance signal is input to the input terminal 80. Become. Further, the configurations of the pre-emphasis circuit and de-emphasis circuit in the column a can be easily inferred from the above explanation of the pre-emphasis circuit and de-emphasis circuit in the columns b and c, so the explanation will be omitted. In addition, in FIG. 16, a pre-emphasis circuit having the configuration shown in FIG. 15 may be inserted into the feedback loop of the differential amplifier 82 to obtain de-emphasis characteristics. (Application example) Note that the present invention is not limited to the above embodiments, but includes a pre-emphasis circuit 14 and a de-emphasis circuit 26 in the luminance signal transmission path, and a pre-emphasis circuit 2 in the carrier color signal transmission path.
9. The device may be configured to include a de-emphasis circuit 30 (that is, pre-emphasis and de-emphasis may be performed separately on both the luminance signal and the carrier color signal). Also, the 6th
Pre-emphasis and de-emphasis may be performed on the carrier chrominance signal in the first embodiment shown in the figure, and on the luminance signal in the embodiment shown in FIG. 7, with respect to spatial frequencies in the vertical direction. The luminance signal in FIG. 7 may be further subjected to horizontal emphasis. In addition, delay circuits 35, 42, 58, 65, 85
Each delay time has been explained as being around a period that is a natural number multiple of one field and a period that is a natural number multiple of H. However, by adding or subtracting a number of hours to this delay time, By obtaining the delay time by adding or subtracting an arbitrary time shorter than 180 ns, which is the time required to horizontally scan two adjacent horizontal scanning lines by the vertical distance (interval) on the screen, It is also possible to perform emphasis in a diagonal direction with respect to the direction and the vertical direction of the screen. The above delay time may be determined by selecting the delay time of the delay circuit 35 or the like, or by selecting the delay time of the delay circuit 35 or the like, or the delay time of the phase adjuster 60, 6.
7, 87 may be adjusted. Furthermore, it can be applied to PAL color video signals, in which case the pre-emphasis circuit 29
Delay circuit 58 and de-emphasis circuit 3 in
The delay times of the delay circuit 65 in 0 and furthermore the delay circuit 85 and the addition/subtraction operations of the arithmetic circuits 56, 64, and 84 are as follows. This is because in the carrier color signal of the PAL system, the carrier wave of one of the two color difference signals is inverted every 1H, and approximately 1/4 of the carrier wave is inverted every 1H.
This is because the phase is offset by H and furthermore, the phase is inverted for each frame.Also, in order to perform pre-emphasis and de-emphasis on the time frequency, it is necessary to select a time that is extremely close to a period that is a natural number multiple of one field. It is. Set the delay time to 8m field (however, m=0,
1, 2,…), (8m+1) field+1.5H,
(8m+2) Field -1.0H, (8m+3)
Field +0.5H, (8m+4) field ±
2.0H, (8m+5) field -0.5H,
(8m+6) field +1.0H, and (8m+7)
When the field is -1.5H, the input and output are in phase, so the arithmetic circuits 56, 64, and 84 perform addition operations. Meanwhile, the delay time is 8m field ±2H,
(8m+1) field -0.5H, (8m+2) field +1.0H, (m+3) field -
1.5H, (8m+4) field, (8m+5)
Field +1.5H, (8m+6) Field -
In the case of 1.0H and (8m+7) field +0.5H, the input and output are in reverse phase, so the calculation circuits 56, 64,
84 is a subtraction operation. (Effects of the Invention) As described above, according to the device of the present invention, de-emphasis is performed on the frequency characteristics in the time axis direction of at least one of the reproduced luminance signal and the luminance signal carrier color signal. Therefore, it has the following features. Since de-emphasis can be performed independent of the horizontal or vertical spatial frequency of the video signal,
It has a noise reduction effect even on noise that cannot be removed by in-screen de-emphasis in the horizontal direction, vertical direction, etc., and can therefore improve the S/N ratio of the reproduced luminance signal and/or the reproduced carrier color signal. , without degrading vertical resolution. Depending on the amplitude of the input signal, non-linear de-emphasis is performed such that when the amplitude is large, de-emphasis is not performed much in the time axis direction. It is possible to reduce the amount of overshoot that occurs, thereby reducing the amount of information discarded due to white clips and dark clips.
Deterioration in image quality after edges (such as at the time of screen switching) can be reduced. In the reproducing device equipped with the above-mentioned non-linear de-emphasis circuit, the amplitudes of the luminance signal and the carrier color signal are not so attenuated and reproduced.
Even if the luminance signal and carrier color signal reproduced from the magnetic tape recorded by the current VTR are passed through a non-linear de-emphasis circuit, they can be restored to approximately the original signal waveform with virtually no problems, and therefore playback is compatible with the current VTR. can.

[Brief explanation of drawings]

Fig. 1 is a block system diagram showing an outline of the video circuit system of a general video signal recording/reproducing device, Fig. 2A,
B is a diagram showing a conventional pre-emphasis circuit and its frequency characteristics, FIGS. 3A and 3B are diagrams each showing a conventional de-emphasis circuit and its frequency characteristics, and FIG. 4 is a diagram explaining a conventional pre-emphasis and de-emphasis method. 5A and 5B are diagrams showing input signal and output signal waveforms of a conventional pre-emphasis circuit, FIGS. 6 and 7 are block diagrams showing respective embodiments of the device of the present invention, and FIGS. 8 and 10. 11 and 11 are block system diagrams respectively showing the first to third embodiments of the pre-emphasis circuit in the block system shown in FIG. 6, and FIG. 9 is a first embodiment of the de-emphasis circuit in the block system shown in FIG. 6. 12, 14 and 15 are block system diagrams showing the first to third embodiments of the pre-emphasis circuit in the block system shown in FIG. 7, and FIG. 13 is the block system diagram shown in FIG. FIG. 16 is a block system diagram showing a first embodiment of the de-emphasis circuit in the illustrated block system, and FIG. 16 is a block system diagram showing another embodiment of the main part of the device of the present invention. 2...Pre-emphasis circuit, 5, 19...Magnetic tape, 8...De-emphasis circuit, 11...
. . . Color video signal input terminal, 12, 23 . 24...Reproduction luminance signal processing circuit, 25...Reproduction carrier color signal processing circuit, 26...De-emphasis circuit for reproduction luminance signal, 28...Reproduction color video signal output terminal, 29...Pre-emphasis circuit for carrier color signal, 30 ... De-emphasis circuit for reproduced carrier color signal, 32 ... Luminance signal input terminal, 3
4, 57, 89, 92...subtraction circuit, 35, 4
2, 58, 65, 85...Delay circuit, 36, 3
7, 43, 44, 46, 47, 48, 50, 5
9,61,66,68,71,72,73,7
5, 86, 88, 91...Coefficient circuit, 38, 52
...Pre-emphasized luminance signal output terminal, 39
...Reproduced luminance signal input terminal, 45...Reproduced de-emphasis luminance signal output terminal, 49, 74, 9
0...Non-linear circuit, 55...Carrier color signal input terminal, 56, 64, 84... Arithmetic circuit, 60, 6
7, 87... Phase adjuster, 62... Pre-emphasized carrier color signal output terminal, 63... Regenerated carrier color signal input terminal, 70, 77... De-emphasized reproduced carrier color signal output terminal, 80... Input terminal,
82... Differential amplifier, 95... Output terminal.

Claims (1)

[Claims] 1. A luminance signal and a carrier color signal separated from a color video signal are converted into a predetermined signal format suitable for recording and reproduction by separate recording signal processing circuits, and then both signals are multiplexed and recorded. After separating the luminance signal and the carrier chrominance signal, each converted into a predetermined signal form, from the multiplexed signal reproduced from the recorded recording medium, the reproduced luminance signal and the reproduced carrier chrominance signal in the original signal form are passed through separate reproduction signal processing circuits. In the video signal reproducing apparatus that obtains a signal, a signal in the time axis direction is applied to at least one of the reproduced luminance signal and the reproduced carrier color signal in the original signal form extracted from the reproduced signal processing circuit. 1. A video signal reproducing device comprising a de-emphasis circuit that provides a characteristic in which high-frequency components are relatively attenuated in level compared to low-frequency components. 2. After converting the luminance signal and carrier color signal separated from the color video signal into a predetermined signal format suitable for recording and reproduction by separate recording signal processing circuits, the recording medium on which both signals were multiplexed and recorded was reproduced. A video signal reproducing device which separates a luminance signal and a carrier chrominance signal, each converted into a predetermined signal form, from a multiplexed signal and passes them through separate reproduction signal processing circuits to obtain a reproduced luminance signal and a reproduced carrier chrominance signal in the original signal form. At the time, high frequency components in the time axis direction are detected in at least one of the reproduced luminance signal and the reproduced carrier color signal in the original signal form extracted from the reproduced signal processing circuit. 1. A video signal reproducing device comprising a de-emphasis circuit that provides a non-linear characteristic whose level is relatively attenuated according to the amplitude of an input signal compared to a low-frequency component.