JPH0410793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a carrier color signal forming a color video signal and a luminance signal which is a frequency modulated signal, and a signal between the respective frequency bands of the carrier color signal and the luminance signal. A magnetic head that sequentially forms a recording track on a magnetic recording medium by mixing a frequency modulated signal occupying a frequency band with an audio signal reduces interference caused to the audio signal by the carrier color signal and the luminance signal. The present invention relates to a video signal and audio signal recording device for recording video signals and audio signals.

Background Art and Problems When a color television signal is recorded on a magnetic tape, the carrier color signal and luminance signal that form the color video signal are separated, and the carrier color signal is frequency-converted to a lower frequency band. After the brightness signal is converted into a frequency modulation (hereinafter referred to as FM modulation) signal on the high frequency band side, the two are mixed to create a recording track (hereinafter referred to as a tilted track) that is arranged at an angle with respect to the running direction of the magnetic tape. The mainstream format is that the audio signal is recorded using a recording track (hereinafter referred to as an audio track) extending in a direction along the running direction of the magnetic tape.

In such a recording format, a color video signal, that is, a carrier color signal converted to a low frequency band and a luminance signal converted to an FM modulated signal on the high frequency side are recorded on the gradient track, and both of these signals are supplied. Two rotating magnetic heads alternately scan the magnetic tape at an angle with respect to its traveling direction, thereby increasing the recording density and enabling long-term recording. To this end, it has been proposed not to provide gaps, so-called guard bands, between adjacent inclined tracks, but to allow the inclined tracks to be adjacent to each other. In this case, crosstalk between adjacent tilted tracks becomes a problem during playback, but by making the azimuth angles of the two rotating magnetic heads different from each other, the FM on the high frequency side during playback can be improved.
The azimuth loss for crosstalk components from adjacent tracks regarding the luminance signal used as a modulation signal is increased, and for the carrier chrominance signal that has been low-pass converted and has a small azimuth loss effect,
For example, the phase is recorded continuously in every other inclined track, and inverted every horizontal period in the remaining inclined tracks, so that the reproduced conveyance color By subjecting the signal to a predetermined phase restoration and passing it through a comb-shaped characteristic filter, crosstalk components from adjacent tracks can be removed, thereby solving the problem of crosstalk. Further, the audio track is continuously formed, for example, at the upper end of the magnetic tape by constantly contacting the running magnetic tape with a fixed head that receives audio signals.

By the way, when high-density recording of color video signals as described above is attempted, the running speed of the magnetic tape increases while the relative speed between the magnetic tape and the rotating magnetic head is maintained at a predetermined level. be made extremely slow. As a result, the relative speed between the fixed head forming the audio track and the magnetic tape becomes extremely low, resulting in a disadvantage that the quality of the recorded audio signal deteriorates.

Therefore, the audio signal is mixed with the color video signal as an FM modulated signal, supplied to the rotating magnetic head, and recorded on the inclined track together with the color video signal, so that the recorded audio signal can be transferred between the recording head and the magnetic tape. In addition, it is possible to reproduce color video signals and audio signals from the magnetic tape recorded in this way using a rotating magnetic head. A magnetic recording/reproducing device has been proposed. According to such a device, it is possible to prevent the quality of the recorded audio signal from deteriorating due to the low relative speed between the recording head and the magnetic tape, and it is also possible to perform speed changes such as slow playback and double speed playback on the recorded magnetic tape. During playback, the relative speed between the rotating magnetic head and the magnetic tape is the same as during normal playback, where the relative speed between the rotating magnetic head and the magnetic tape is the same as during recording. Since the signal does not change significantly compared to the conventional one, it is possible to obtain a reproduced audio signal from the rotating magnetic head that is not much different from that during normal reproduction, and therefore has the advantage of being able to obtain reproduced audio that is worth listening to. .

However, when recording is performed using such a device, the frequency band occupied by the audio signal converted into an FM modulated signal is The carrier chrominance signal and the FM modulation signal are placed close to each other between the respective frequency bands of the chrominance signal and the luminance signal, which is made into the FM modulation signal, and therefore the audio signal, which is made into the FM modulation signal, is low-band converted. There is a problem of interference caused by the luminance signal used as a signal. In other words, within the frequency band of the audio signal converted into an FM modulated signal, there are upper sideband components forming the high band part of the carrier color signal converted to a lower band, and lower sideband components forming the lower band part of the luminance signal converted into the FM modulated signal. Sideband components mix and interfere, and in the audio signal that is reproduced from the magnetic recording medium on which such recording is made and is made into an FM modulated signal, the level of the mixed carrier color signal component and luminance signal component becomes higher than the audio signal. A phenomenon in which the demodulation of the audio signal is not properly performed at such a portion due to the occurrence of a portion where the signal level is higher than that of the signal, that is, “audio signal breakage” occurs, or such a magnetic recording medium This causes problems such as beat noise in the reproduced audio signal obtained by demodulating the audio signal reproduced from the FM modulated signal.

Such a low-pass converted carrier color signal and FM
In order to prevent the interference of the luminance signal, which is used as a modulated signal, with the audio signal, which is used as an FM modulated signal, a band removal filter corresponding to the frequency band of the audio signal, which is used as an FM modulated signal, is used. A part of the upper sideband of the carrier chrominance signal and a part of the lower sideband of the luminance signal made into an FM modulated signal are removed to create a sufficient frequency band space for the audio signal made into an FM modulated signal. It is conceivable to insert an audio signal as an FM modulated signal after that. However, such a method uses low-pass converted carrier color signals and FM
This is not desirable because it unnecessarily narrows the frequency band of the luminance signal used as the modulation signal and deteriorates the frequency band characteristics of both signals.

Purpose of the Invention In view of the above, the present invention provides a low-pass-converted carrier color signal that forms a color video signal and a luminance signal that is made into an FM modulation signal, and a frequency band between the respective frequency bands of these signals. When mixing the FM modulated signal with the audio signal and recording it on a magnetic recording medium with a magnetic head, the frequency band characteristics of the low-frequency converted carrier color signal and the FM modulated luminance signal are minimized. It is an object of the present invention to provide a video signal and audio signal recording device that can reduce the interference of these carrier color signals and luminance signals with audio signals converted into FM modulated signals without causing deterioration. .

Summary of the Invention The video signal and audio signal recording device according to the present invention occupies a color signal frequency-converted to the lower frequency side and a frequency band higher than the frequency band of the color signal.
A video signal circuit unit that obtains a video signal consisting of a luminance signal made into an FM modulated signal, and a frequency band between the frequency band of the color signal whose frequency is converted to the lower frequency side and the frequency band of the brightness signal made into the FM modulated signal. An audio signal circuit section obtains an audio signal as an FM modulated signal occupying a frequency band, and a video signal obtained from the video signal circuit section and an audio signal obtained from the audio signal circuit section are mixed and recorded on a magnetic recording medium. The video signal circuit section includes a mixing circuit section that supplies signals to the magnetic head that sequentially forms a recording track, and a video signal circuit section that outputs an FM modulated signal mixed within the frequency band of the audio signal converted into an FM modulated signal. If the level of the low frequency part of the luminance signal and/or the high frequency part of the color signal frequency-converted to the low frequency side exceeds a predetermined level, /or the frequency band of the high frequency part of the color signal is narrowed, the low frequency part of the luminance signal is made into an FM modulated signal that mixes in the frequency band of the audio signal, and/or the color signal whose frequency is converted to the low frequency side It is configured to include a frequency band control section that operates to keep the level of the high frequency region below a predetermined level. With this configuration, for example, the signal may be mixed in the frequency band of an audio signal that is an FM modulated signal.
When the level of the lower sideband component forming the low frequency part of the luminance signal converted into the FM modulation signal is high, the lower sideband component of the luminance signal converted into the FM modulation signal is narrowed.
of the lower sideband component of the luminance signal as an FM modulated signal.
Interference with the audio signal as an FM modulated signal is prevented, while when the above-mentioned level is small,
The lower sideband of the luminance signal made into an FM modulated signal is hardly narrowed, so that the frequency band characteristics of the luminance signal made into an FM modulated signal are not substantially degraded. Similar processing can be performed on the upper sideband component that constitutes the high frequency portion of the color signal that has been subjected to frequency conversion.

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

FIG. 1 shows a main part of an example of a video signal and audio signal recording device according to the present invention. In this example, two channels of stereo left and right signals are supplied as audio signals, and these two channels of audio signals are mixed with a color video signal as four FM modulated audio signals, first to fourth. , which is designed to be recorded on a magnetic recording medium.

In this example, a color signal input terminal 1 supplies a carrier color signal C ₀ forming a color video signal.
This carrier color signal C ₀ is supplied to the frequency conversion circuit 3 via the automatic color signal level control circuit 2, and from this frequency conversion circuit 3, the frequency is changed to the low frequency band side so that the carrier wave frequency f _c becomes, for example, 688kHz. The converted, low-pass converted carrier color signal (hereinafter referred to as
A low-pass converted color signal) C is obtained, which is extracted through a low-pass filter 4. In addition, in the frequency conversion circuit 3, when recording is performed in which adjacent recording tracks on a magnetic recording medium are adjacent to each other as described above, in order to remove crosstalk components from adjacent tracks during reproduction,
The phase of the low frequency conversion color signal C is controlled.

From the luminance signal input terminal 5, a luminance signal _ln forming a color video signal together with the carrier color signal _C0 is supplied. This luminance signal l _n is obtained by resistor 6 and variable resistor 7.
The luminance signal ( (hereinafter referred to as FM brightness signal)
LM is obtained, which is extracted through a high-pass filter 13. In this FM luminance signal LM, the tip of the synchronization signal of the luminance signal l _n has a frequency f _s , for example,
FM modulation is performed such that f _s = 4 MHz, and the white peak (maximum amplitude part) is a frequency f _p higher than f _s by a predetermined amount, for example, 1.2 MHz, for example, f _p = 5.2 MHz. can get.

The frequency spectra of the low-pass converted color signal C obtained from the above-mentioned low-pass filter 4 and the FM luminance signal LM obtained from the high-pass filter 13 are shown in FIG. 2 (vertical axis is level l, horizontal axis is frequency l). f), the frequency band of the low-frequency converted color signal C having the carrier frequency f _c is located on the low-frequency side,
The frequency band of the FM luminance signal LM is expanded to the high-frequency side.
In FIG. 2, between the upper limit of the band of the low-frequency conversion color signal C and the lower limit of the band of the FM luminance signal LM, a frequency band A indicated by a dotted line is
This is the band that should be occupied by an audio signal converted into an FM modulated signal, which will be described later. In this frequency band A, the center frequency f _a is, for example, about 1.56MHz and the width is about 0.62MHz, and the upper sideband that forms the high frequency part of the low-frequency conversion color signal C enters the lower limit side, and the upper limit side is about 0.62MHz. On the side, a lower sideband forming the low frequency portion of the FM luminance signal LM regulated by the high-pass filter 13 enters.

The low-pass converted color signal C obtained from the low-pass filter 4 is transmitted through a resistor 14, a coil 15, and a capacitor 16.
The signal is supplied to a mixing circuit 19 and a bandpass filter 20 via a variable trap circuit 18 formed of a variable resistor 17 and a variable resistor 17. This variable trap circuit 18
The trap center frequency is set to match the center frequency f _a of the frequency band A mentioned above, and therefore, the attenuation band of the variable trap circuit 18 allows the upper limit side of the band of the low-frequency converted color signal C to be That is, the upper limit of the upper sideband is regulated. The bandpass filter 20 has a frequency band A as its passband, and therefore, on its output side, an upper sideband component C forming the high frequency part of the low frequency converted color signal C that falls into the frequency band A. _u is obtained. This upper sideband component C _u is supplied to the level detection circuit 21, and a detection output corresponding to the level detected from the level detection circuit 21 is obtained, and this detection output is sent to the time constant circuit 21.
2. From the time constant circuit 22, in response to changes in the rise and fall of the detection output from the level detection circuit 21, for example, gradual rises and falls with rise and fall times within one horizontal period are generated. An output indicating a change in is obtained, and this is supplied to the control end of the variable resistor 17. The resistance value of the variable resistor 17 decreases as the output of the time constant circuit 22 increases, and as a result, the attenuation band of the variable trap circuit 18 expands as the output of the time constant circuit 22 increases. do. Therefore, the attenuation band of the variable trap circuit 18 is changed according to the level of the upper sideband component C _u obtained from the bandpass filter 20.
As the level of C _u increases, the attenuation band of the variable trap circuit 18 expands, and as a result, the upper side band of the low-frequency converted color signal C is narrowed, and the upper side band component that enters the frequency band A The level of C _u is reduced. In other words, the upper sideband component C _u of the low frequency converted color signal C entering the frequency band A is prevented from exceeding a predetermined level. Then, when the level of the upper sideband component C _u is below a predetermined level, the upper sideband of the low frequency conversion color signal C is not narrowed. Note that since the time constant circuit 22 is provided, even if the level of the upper sideband component C _u exceeds a predetermined value, if the duration is less than the predetermined time determined by the time constant circuit 22, the low frequency The upper sideband of the converted color signal C is not narrowed. In this way, the mixing circuit 19 receives a low-frequency converted color signal C that prevents the upper sideband C _u entering the frequency band A from exceeding a predetermined level.
is supplied.

On the other hand, the FM obtained from the high-pass filter 13
The luminance signal LM is supplied to a mixing circuit 19 and a bandpass filter 23. Band pass filter 23
Similar to the bandpass filter 20, the frequency band A
Therefore, the lower sideband component LM _l , which constitutes the low frequency part of the FM luminance signal LM that falls into the frequency band A, is obtained on the output side. This lower sideband component LM _l is the level detection circuit 24
A detection output corresponding to the detected level is obtained from the level detection circuit 24, and this detection output is supplied to the time constant circuit 25. Time constant circuit 2
5 to 1, for example, in response to changes in the rise and fall of the detection output from the level detection circuit 24.
An output showing gradual rise and fall changes with rise and fall times within the horizontal period is obtained, which is fed to the control end of the variable resistor 7 of the variable low-pass filter 9. The resistance value of the variable resistor 7 decreases as the output of the time constant circuit 25 increases, so that the pass band of the variable low-pass filter 9 changes as the output of the time constant circuit 25 increases. Therefore, the range is narrowed to the low frequency side. Therefore, the passband of the variable low-pass filter 9 is changed according to the level of the lower sideband component LM _l obtained from the bandpass filter 23. In this case, the lower sideband component LM _l is As the value increases, the passband of the variable low-pass filter 9 is narrowed to the lower side, and the luminance signal l _n passing through the variable low-pass filter 9
As a result, the highest modulation frequency in the FM modulation circuit 12 is reduced, and the lower side band of the FM luminance signal LM is substantially narrowed. As a result, the level of the lower sideband component LM _l entering the frequency band A is reduced. That is, the lower sideband component LM _l of the FM luminance signal LM entering the frequency band A is prevented from exceeding a predetermined level.
Then, when the level of the lower sideband component LM _l is below a predetermined level, the lower sideband of the FM luminance signal LM is not narrowed. Note that since the time constant circuit 25 is provided, even if the level of the lower sideband component LM _l exceeds a predetermined level, the duration time is determined by the time constant circuit 2.
If the time is less than the prescribed time specified in 5.
The lower sideband of the FM luminance signal LM is not narrowed.
In this way, the mixing circuit 19 has frequency band A.
The FM luminance signal LM is supplied in such a way that the lower sideband component LM _l entering the FM luminance signal does not exceed a predetermined level.

As described above, the low-pass converted color signal C and the FM luminance signal LM are made such that the upper sideband component C _u and lower sideband component LM _l entering the frequency band A do not exceed a predetermined level. The mixed signals are mixed in a mixing circuit 19, and the composite signal is supplied to mixing circuits 26 and 27 as a video signal V to be recorded. Here, the circuit configuration from the color signal input terminal 1 and the luminance signal input terminal 5 to the mixing circuit 19 forms a video signal circuit section that obtains the video signal V consisting of the low-frequency converted color signal C and the FM modulated luminance signal. This means that

Furthermore, left signal SL and right signal SR of stereo audio signals are supplied to audio signal input terminals 31 and 32, respectively. This left signal SL passes through an automatic gain control amplifier circuit 33, a pre-emphasis circuit 34, and a clamp circuit 35 in order, and is supplied to first and second FM modulation circuits 36 and 37, respectively. Also,
Similarly, the right signal SR is also connected to the automatic gain control amplifier circuit 3.
8, a pre-emphasis circuit 39, a clamp circuit 40, and then supplied to third and fourth FM modulation circuits 41 and 42, respectively. The first and second FM modulation circuits 36 and 37 have frequencies f ₁ and
Frequency f ₂ higher than f ₁ , e.g. f ₁ = 1.33MHz and f ₂ =
1.48MHz carrier wave with the same frequency deviation width for the left signal SL, for example, about 100 to 150kHz.
FM modulation is performed, and left signals (hereinafter referred to as left FM signals) LF ₁ and LF ₂ , which are FM modulated signals having mutually different frequency shift bands, are obtained at each output end.
Further, third and fourth FM modulation circuits 41 and 42
is a carrier wave with a frequency f ₃ higher than f ₂ and a frequency f ₄ higher than f ₃ , for example, f ₃ = 1.63 MHz and f ₄ = 1.78 MHz, respectively, with the same frequency deviation width as above in the right signal SR. Right signals RF ₃ and RF ₄ (hereinafter referred to as right FM signals) which are FM modulated signals with different frequency shift bands are obtained at each output end. The two left FM signals obtained in this way
LF ₁ and LF ₂ and the two right FM signals RF ₃ and RF ₄ are
Corresponding bandpass filters 43, 44, 4, respectively.
5 and 46. These left FM signals LF ₁
and LF ₂ , and the right FM signals RF ₃ and RF ₄ have frequency spectra as shown in Figure 3 (horizontal axis is frequency/f)
As shown in Figure 2, the frequency shift bands are different and are located at regular intervals, but the adjacent frequency shift bands are very close to each other and the overall frequency band is relatively small. It is narrow and located in the frequency band A mentioned above.

The left FM signal LF ₁ and the right FM signal RF ₃ from the bandpass filters 43 and 45 are mixed by a mixing circuit 47 and supplied to an amplifier circuit 48 . Also, the left FM signal LF ₂ from bandpass filters 44 and 46
and the right FM signal RF ₄ are mixed in a mixing circuit 49,
The signal is supplied to the amplifier circuit 50. And the amplifier circuit 4
The mixed output of the left FM signal LF ₁ and the right FM signal RF ₃ from the amplifier circuit 50 is supplied to the mixing circuit 26, and the mixed output of the left FM signal LF ₂ and the right FM signal RF ₄ from the amplifier circuit 50 is supplied to the mixing circuit 27. supplied to Here, audio signal input terminals 31 and 32 are connected to amplifier circuits 48 and 50.
The circuit configuration up to forms an audio signal circuit section that obtains an audio signal converted into an FM modulated signal.

Then, in the mixing circuit 26, the mixing circuit 19
The video signal V from the mixing circuit 19 is mixed with the left FM signal LF ₁ and the right FM signal RF ₃ , and in the mixing circuit 27, the video signal V from the mixing circuit 19 and the left FM signal are mixed.
LF ₂ and the right FM signal RF ₄ are mixed. As mentioned above, the left FM signals LF ₁ and LF ₂ and the right FM signal
Since RF ₃ and RF ₄ are located within the frequency band A mentioned above, from the mixing circuit 26,
A composite signal of the low-pass converted color signal C, the FM luminance signal LM, and the left FM signal LF ₁ and right FM signal RF ₃ inserted into the frequency band A between the frequency bands of these two signals is obtained, and , the mixing circuit 27 synthesizes the low frequency conversion color signal C, the FM luminance signal LM, and the left FM signal LF ₂ and right FM signal RF ₄ inserted into the frequency band A between the frequency bands of these two signals. I get a signal. In this case, the frequency band A includes the upper sideband component C _u of the low-frequency conversion color signal C and the FM luminance signal.
Since the upper sideband component LM _l of the LM is prevented from being mixed in at a level higher than a predetermined level, the low frequency conversion color signal for the left FM signals LF ₁ and LF ₂ and the right FM signals RF ₃ and RF ₄ is prevented. The upper sideband component of C or
The interference of the lower sideband components of the FM luminance signal LM is significantly reduced.

Mixing circuits 26 and 27 thus obtained
The composite signals from the recording amplifiers are supplied to rotating magnetic heads 53 and 54 via recording amplifier circuits 51 and 52, respectively. These rotating magnetic heads 53 and 54
are assumed to have different azimuth angles,
Inclined tracks without guard bands are alternately formed on the magnetic tape, and the composite signal from the mixing circuit 26 and the composite signal from the mixing circuit 27 are recorded alternately.

As described above, the low-pass _converted color signal C _and By controlling the sidebands of the FM luminance signal LM, it is possible to reduce the The upper sideband component of the gamut-converted color signal C and
With the interference of the lower sideband component of the FM luminance signal LM with the audio signal, which is an FM modulated signal, being significantly reduced, the low frequency converted color signal C, the FM luminance signal LM
It is possible to mix and record the audio signal and the FM modulated signal.

In addition, in this example, the time constant circuits 22 and 2
5 is provided for the upper sideband component forming the high band part of the low band conversion color signal C for the audio signal converted into the FM modulated signal or the lower sideband component forming the low band part of the FM luminance signal LM. Even if there is interference at a level higher than the predetermined level, it will not have a substantial adverse effect on the reproduced audio signal if it is for an extremely short period of time, for example, several microseconds or less. This is because there is no need to narrow the sideband of the low-pass converted color signal C or the FM luminance signal LM, and only when the above-mentioned interference continues for more than a predetermined time, the sideband of the low-pass converted color signal C or the FM luminance signal LM is narrowed. This is to narrow the sideband.

Furthermore, in the example of FIG. 1, in order to control the sideband of the luminance signal _ln , the pre-emphasis circuit 1
The variable low-pass filter 9 disposed on the input side of the pre-emphasis circuit 10 may also be disposed on the output side of the pre-emphasis circuit 10.

FIG. 4 shows parts of another example of the video signal and audio signal recording device according to the present invention, and parts corresponding to the parts shown in FIG. 1 are given the same reference numerals as in FIG. 1. . In this example, the resistance value of the variable resistor 17 in the variable trap circuit 18 for controlling the sideband of the low frequency converted color signal C is the same as that for controlling the sideband of the luminance signal _ln . They are commonly controlled by the output of a time constant circuit 25, which controls the resistance value of the variable resistor 7 in the variable low-pass filter 9. Therefore, in this case,
According to the level of the lower sideband component LM _l of the FM brightness signal LM that falls into the frequency band A shown in FIG. 2, the lower sideband component LM l of the FM brightness signal LM is controlled and the lower sideband component LM _l is At the same time, the upper sideband of the low-pass converted color signal C is also controlled, and the upper sideband component C _u of the low-pass converted color signal C that falls into the frequency band A is set to a predetermined level. It is designed not to become more than that. Other configurations and operations are similar to the example shown in FIG.

FIG. 5 shows a portion of still another example of the video signal and audio signal recording device according to the present invention. This example:
In the example shown in FIG. 1, the variable low-pass filter 9 is removed and the FM luminance signal LM
A variable trap circuit 18' formed of a resistor 14', a coil 15', a capacitor 16', and a variable resistor 17' is provided on the output side of the high-pass filter 13, which provides This corresponds to a configuration in which the output of the time constant circuit 25 is supplied to the control end of the circuit 17'.

The variable trap circuit 18' is similar to the variable trap circuit 18 provided for controlling the sideband of the low frequency converted color signal C in the example shown in FIG. The attenuation band is assumed to correspond to the center frequency f _a of the frequency band A shown in FIG. 2, and as the resistance value of the variable resistor 17' becomes smaller, the attenuation band becomes wider. Therefore, due to the attenuation band of the variable trap circuit 18',
The lower limit of the band of the FM luminance signal LM, that is, the lower limit of the lower sideband, is regulated, and the variable resistor 1
The resistance value of 7' is made to decrease as the output of the time constant circuit 25 increases, and therefore,
The attenuation band of the variable trap circuit 18' is the lower sideband component of the FM luminance signal LM that falls into the frequency band A.
As the level of LM _l increases, it expands, so in this case as well, as the level of the lower sideband component LM _l increases, the lower sideband of the FM luminance signal LM increases. control is performed so that the lower sideband component LM _l does not exceed a predetermined level. The other parts are the same as the example shown in FIG.

Furthermore, the above-mentioned control of the sideband of the FM luminance signal LM can also be performed in the pre-emphasis circuit 10 for the luminance signal l _n in each of the above-mentioned examples. FIG. 6 shows an example of a specific configuration of the pre-emphasis circuit 10 in such a case. Here, the pre-emphasis circuit 10 performs a non-linear emphasis operation, and a luminance signal l _n is supplied to the base, and a load resistor 6 is supplied to the collector.
An emphasis section 64 has a resistor 62 and a capacitor 63 connected in parallel between the emitter of a transistor 61 connected to 0 and ground, and a capacitor 65, resistors 66 and 67, diodes 68 and 69, and a capacitor 65 connected to the output side thereof. The compressor section 71 is formed of a variable voltage source 70. Then, the variable voltage source 70 in the compressor section 71
By changing the voltage value of, for example, by the output of the time constant circuit 25 shown in FIG _.
As a result, the luminance signal l _n obtained at the output terminal 72 of the pre-emphasis circuit 10 is controlled by the sideband components of the FM luminance signal LM supplied to the FM modulation circuit 12. Level controlled. In that case, as the output of the time constant circuit 25 increases, the level of the sideband component of the FM luminance signal LM decreases, and the sideband component of the FM luminance signal LM is substantially narrowed. , the lower sideband component LM _l of the FM luminance signal LM falling into the frequency band A shown in FIG. 2 is prevented from exceeding a predetermined level.

Note that in the above example, the low-frequency conversion color signal C
Both the sideband of the FM luminance signal LM and the sideband of the FM luminance signal LM are controlled, but only one of these controls, for example,
Only the sidebands of the FM luminance signal LM may be controlled.

Effects of the Invention As is clear from the above description, according to the video signal and audio signal recording device according to the present invention, the color signal frequency-converted to the lower frequency side and the luminance converted into the FM modulated signal form a color video signal. When recording on a magnetic recording medium with a common magnetic head by mixing a signal and an audio signal that is an FM modulated signal that occupies a frequency band between the respective frequency bands of these two signals, the audio signal that is an FM modulated signal is mixed. The level of the sideband component that forms the low frequency part of the luminance signal that is an FM modulated signal mixed in the frequency band of the audio signal, or
Furthermore, the level of the sideband component forming the high frequency part of the color signal frequency-converted to the low frequency side is detected, and depending on the detection level, the sideband component and the low frequency side of the luminance signal, which is converted into an FM modulation signal, are detected. At least one of the sidebands of the frequency-converted color signal is controlled and the FM
A sideband component that forms the low frequency range of a luminance signal that is an FM modulated signal that enters the frequency band of an audio signal that is a modulated signal, and a sideband that forms a high frequency range of a color signal that has been frequency-converted to the low frequency side. Since the component is prevented from exceeding a predetermined level, the frequency band of the color signal converted to the low frequency side and the luminance signal converted to the FM modulation signal is not narrowed more than necessary. Frequency-converted color and luminance signals
Interference with audio signals converted into FM modulated signals can be significantly reduced. Therefore, the frequency band characteristics of the frequency-converted chrominance signal and the luminance signal converted into an FM modulated signal are kept as low as possible to be recorded on the low frequency side, and the frequency band characteristics of the audio signal converted into an FM modulated signal are not deteriorated as much as possible. Eliminate the occurrence of "audio signal breakage" and beat noise in the reproduced audio signal due to interference of the color signal frequency-converted to the lower frequency side and the luminance signal converted to the FM modulation signal. You will be able to do that.

[Brief explanation of drawings]

FIG. 1 is a block connection diagram showing essential parts of an example of a video signal and audio signal recording device according to the present invention, and FIG.
3 and 3 are frequency spectrum diagrams used to explain the operation of the example shown in FIG. FIG. 3 is a block connection diagram and a circuit diagram showing an example part of FIG. In the figure, 1 is a color signal input terminal, 3 is a frequency conversion circuit, 4 is a low-pass filter, 5 is a luminance signal input terminal, 9 is a variable low-pass filter, 10 is a pre-emphasis circuit, 12, 36, 37 , 41 and 4
2 is an FM modulation circuit, 13 is a high-pass filter, 1
8 and 18' are variable trap circuits, 19, 26,
27, 47 and 49 are mixing circuits, 20 and 23 are band pass filters, 21 and 24 are level detection circuits, 22 and 25 are time constant circuits, 31 and 32 are audio signal input terminals, and 53 and 54 are rotating magnetic heads. be.

Claims (1)

[Claims] 1. A video signal for obtaining a video signal consisting of a color signal frequency-converted to the lower frequency side and a luminance signal that is a frequency modulated signal occupying a frequency band higher than the frequency band of the color signal. a circuit section, an audio signal circuit section for obtaining an audio signal as a frequency modulated signal occupying a frequency band between the frequency band of the color signal and the frequency band of the luminance signal, and an image obtained from the video signal circuit section. a mixing circuit unit that mixes the signal and the audio signal obtained from the audio signal circuit unit and supplies the mixed signal to a magnetic head that sequentially forms a recording track on a magnetic recording medium, the video signal circuit unit However, the low frequency part and/or the luminance signal mixed in the frequency band of the audio signal are
Alternatively, if the level of the high frequency portion of the color signal exceeds a predetermined level, the frequency band of the low frequency portion of the luminance signal and/or the high frequency portion of the color signal is narrowed and the audio signal is A video signal comprising: a frequency band control unit that operates to reduce the level of the low frequency portion of the luminance signal and/or the high frequency portion of the color signal mixed in the frequency band of the video signal to a predetermined level or less; Audio signal recording device.