JPS6329303A - Video signal recording device - Google Patents

Abstract

PURPOSE:To suppress an inverting phenomenon by emphasizing and recording the level of a part of the lower side band wave of a frequency modulated video signal, setting the level emphasizing quantity of the lower side band wave to a smaller quantity as the frequency modulated video signal has a high carrier frequency and recording it to recording medium. CONSTITUTION:A luminance signal to come into an input terminal is frequency-modulated by an FM modulator 2, and made into a modulated frequency luminance signal (FM luminance signal), and thereafter, an adder circuit 4 adds a low area converting conveying chrominance components are added. At the time of an A mode, the input frequency dividing multiplexing signal of a terminal 5 attenuates a high frequency component including an FA of an FM luminance signal YA, increases the high frequency component of <=1MHz, adds a recording equalizer characteristic and removes it to an output terminal 16. At the time of a B mode, a part of the lower side band wave of an FM luminance signal YB is level-increased, the level increasing quantity is selected to the quantity smaller than the time of the A mode and outputted to the output terminal 16. Thus, after a frequency dividing multiplexing signal including the FM luminance signal is amplified through the output terminal 16 and an electric current amplifier 17 to the necessary level and recorded into the magnetic tape by a rotary head 19. Thus, the occurrence of the inverting phenomenon can be prevented beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal recording device, and more particularly to a video signal recording device that selectively switches the carrier frequency of a frequency-modulated video signal and records it on a recording medium.

2. Description of the Related Art In recent years, there has been an increasing demand for higher resolution video equipment, and various methods have been proposed. For example, a large screen display of 28 inches or more is desired to have a high resolution, and some home-use displays have a horizontal resolution of 560 Tv lines, for example. In addition, in television broadcasting, research is being conducted to further increase the resolution while maintaining compatibility with the current system (for example, the Society of Television Engineers 7J
Vo140, Na3. “Small special feature EDTV and ID-cho V” (May 1986 issue), etc.). Furthermore, among the video signal reproducing devices δ, there is one that realizes a horizontal resolution of 400 TV lines in the case of video disc reproducing “A”.

In response to this trend toward higher image quality, it is desired that higher resolution be achieved even in helical skitton type VTRs using the low frequency conversion color recording and reproducing method.

In the current VTR standard 0 mode (hereinafter referred to as standard quality mode or A mode), the video signal recorded by the recording system (video signal recording device) of such a VTR is as shown in FIG. 5(A). As shown in FIG.
(FM luminance signal YA with a carrier frequency shift of Z and low-pass converted carrier color signal C with a color subcarrier frequency of 629kHz)
It becomes a frequency division multiplexed signal consisting of A.

On the other hand, in recent years, the performance of magnetic tape and the performance of rotary heads have significantly improved. It has become possible to record and play back high-quality images with a higher horizontal M resolution than images recorded and played back in -[- mode (also referred to as B mode). .

Therefore, when focusing only on image quality, the above-mentioned video signal description 8! The device may be configured, but in standard definition mode (A mode), inexpensive magnetic tape can be used, and in high definition mode (8 modes), it is possible to record video signals already recorded on magnetic tape. It has the advantage that it can be reproduced even with a conventional video signal reproducing device dedicated to standard definition mode, which is not compatible with standard definition mode, so it is difficult to abandon standard definition mode. Therefore, the present invention relates to the above, B.
The present invention relates to a video signal recording VA device capable of switching recording between both modes.

Problems to be Solved by the Invention Here, when frequency modulating a video signal (for example, a Ti degree-multiplied signal and recording it on a magnetic recording medium, a recording equalizer is used to emphasize the level of non-sideband waves of the frequency-modulated video signal. Traditionally, it has been done to record the S
/N good reproduction video signal is obtained. However, if the amount of enhancement described above is too large, it will have the effect of emphasizing the lower sideband and suppressing the upper sideband during magnetic recording and reproduction (
For example, NHK Technical Research 21 (4), P, 226-2
72 (19 [39), etc.]. ), the reproduction level of the lower sideband wave becomes extremely large compared to the reproduction level of the upper sideband wave or FM+m transmission, and in this case, it is known that a so-called inversion phenomenon occurs in the reproduced image. .

On the other hand, in magnetic recording and reproduction, there is generally a property that the higher the frequency, the smaller the reproduction output is due to various losses, as shown in FIG. For this reason, in a video signal recording device capable of recording by switching between both A and B modes, if the recording equalizer characteristics are the same in both modes, in the case of B mode (high image quality mode), even if the magnetic recording medium is Even if one with a large area output is used, considering that in B mode (high image quality mode) the FMll & transmission frequency is raised to the limit of the capabilities of the high performance magnetic recording medium to improve resolution. Even if it is appropriate in mode (standard image quality mode), Ff in B mode (high image quality mode)
The reproduction level of the vl carrier wave and the upper side band wave will be lower than the reproduction level of the lower side band wave, making it easy for an inversion phenomenon to occur.

Furthermore, in the case of B mode (high image quality mode), the playback output level of the FM carrier wave is small, and in order to compensate for the negative S/N of the playback signal, the frequency modulated video It is conceivable to increase the frequency shift of the signal, but in that case, the level of sideband waves increases, making inversion more likely to occur.

Therefore, in view of the above points, the present invention provides a video signal recording device that solves the above problems by varying the sideband emphasis ω (of a frequency modulated video signal) to an appropriate value according to the mode. The purpose is to

Means for Solving the Problems The video signal recording device δ of the present invention includes the level of at least a portion of the upper side band of a frequency modulated video signal in two or more modes having different carrier frequencies, and the carrier wave and the upper side band of the frequency modulated video signal. In addition to recording with relative emphasis compared to the level of sideband waves,
The structure is such that a frequency modulated video signal having a higher carrier wave frequency is recorded on a recording medium with the lower side band level emphasis h1 set to a smaller value.

Effect 11 A frequency modulated video signal that is switched to a unique mode and recorded on a recording medium has at least a part of its lower sideband that is relatively emphasized compared to other parts, and the amount of emphasis is A value is selected and recorded according to the mode.

The amount of emphasis of this lower sideband is selected to be smaller as the carrier frequency of the frequency modulated video signal is higher.

As a result, in the process of magnetic recording and reproduction, even if the reproduction output decreases as the frequency increases, the level of the lower sideband wave will not become higher than the levels of the carrier wave and the upper sideband wave at the 8i end.

ACTUAL FLI EXAMPLE FIG. 1 shows a circuit diagram of a first embodiment of the present invention. In the figure, the luminance signal that has entered the input terminal 1 is supplied to the FM modulator 2, which modulates the frequency of the carrier wave to obtain a frequency of 9'J.
After being made into the A luminance signal (FM luminance signal), it is supplied to the adder circuit 4, where it is added (frequency division multiplexed) with the low-frequency converted carrier color signal from the input terminal 3. In addition, FM modulator 2
is configured to be switched to a predetermined carrier wave frequency according to the specified mode by an input control signal input from the terminal 20 specifying either the A or B mode.

As a result, the frequency-divided multi-Φ signal taken out from the adder circuit 1 is as shown in Fig. 5 (
As shown in FIG. 5(B), it consists of an FM luminance signal YA and a low frequency conversion carrier color signal CA, and when the image quality is high (B mode), as shown in FIG. Vj, and a converted carrier color signal Cs. Here, FM Luminance Shinzuki Y
o has a carrier frequency of, for example, 5 at the sync chip level.
．． 4MHz.

The white peak level is selected to be 7.0 MHz, and the carrier frequency is higher than that of the FM luminance signal YA, and ll! The two transmit frequencies are the transmit frequency shifts in the ventricle. Further, the low-band converted carrier color lP'; 308 occupies the same band as the low-band converted carrier color signal CA shown in FIG. 5(A).

The frequency side multiplexed signal of any one of the two types of modes taken out from the adder/Q circuit 4 is 9; child 5.
The signal is supplied to the recording equalizer 1f amplifier 6 via the recording equalizer 1f, where it is given a predetermined recording equalizer characteristic of 1.1. A feedback circuit 15 is provided in the feedback path between the output I- of the recording equalizer amplifier 6 and the input terminal. Feedback circuit 15 includes capacitors 7.10. resistance 8
．． 9. Consisting of a 12° coil 11 and a switch circuit 13, the coil 11. The resistor 12 and the switch circuit 13 are connected in parallel with each other.

The switch circuit 13 receives the switching signal from the input terminal 14! s Off when in semi-quality mode (A mode),
It is configured to be turned on in high image quality mode (8 mode). Therefore, first, to explain the operation at the A'E- mode, since the switch circuit 13 is off at this time, a 9° resistor capacitor 10 and a coil 11 are connected between the input terminal of the recording equalizer amplifier 6 and the ground. The circuit configuration is such that the resistor 12 is connected in parallel to the coil 11, and the coil 11 provides greater feedback as the frequency increases. Therefore, in this A mode, the input frequency of the terminal 5 In the division multiplexed signal, as shown by the solid line ■ in Fig. 2, the high frequency components including the carrier frequency leakage FA of the FM luminance signal YA of the AT need are attenuated, the culm level that becomes the low frequency is emphasized, and the low The low frequency components of 1 MHz or less, where the range-converted carrier color signal CA is present, are enhanced to a maximum of 6 cB and are taken out to the output terminal 16 after being given a recording equalizer characteristic. That is, the lower sideband wave of the FM luminance signal YA is outputted to the output terminal 16 with its level enhanced compared to its carrier wave and upper sideband wave.

Note that the low frequency emphasis characteristic is also created by the 31 emphasis characteristic created by the capacitor 7 and the resistor 8.9 in the feedback loop.

Next, to explain the operation in B mode, since the switch circuit 13 is turned on at this time, the coil 11 and the resistor 12 are short-circuited, and the resistor 9 is connected between the input terminal of the recording equalizer amplifier 6 and the ground. Only the capacitor 10 is connected in series, resulting in an lζ circuit configuration and '8 I&. Therefore, the high frequency feedback over-enhancement effect of the coil 11 is eliminated, and only the high frequency feedback enhancement effect of the capacitor 7 and the resistor 8.9 is achieved.

Therefore, in this 8-mode mode, the terminal 50 input frequency v1
The multiplexed signal is taken out to the output terminal 16 after being given a recording equalizer characteristic in which the imbalance of low frequencies is reduced compared to the A mode, as shown by the dashed line (■) in FIG. That is, in the B-mode FM brightness signal Y8, a part of the lower sideband is enhanced in level compared to the carrier wave and upper sideband of the carrier frequency shift Fa, and the amount of level enhancement is greater than that in the A-mode. is also selected to be small and output to the output terminal 16.

Note that in this embodiment, the level of the lower sideband wave in B mode is only emphasized on a part of the lower sideband wave, but even with this, the desired effect can be obtained practically, and the constant change for switching is possible. is I
! There is a feature that can be achieved in Iko.

In this way, the level of the lower sideband was enhanced.
The frequency component 1 or 1 multiplexed signal of the M luminance signal is supplied to the current amplifier 17 via the output terminal 16, where it is amplified to a required level and then supplied to the rotary head 19 via the rotary transformer 18. and recorded on a magnetic tape (not shown).

Next, a second embodiment of the apparatus of the present invention will be described. FIG. 3 shows a block system diagram of the main parts of the second embodiment of the apparatus of the present invention. In the figure, the same components as in FIG. 1 are given the same reference numerals. In FIG. 3, an A-mode feedback circuit 23 and a B-mode feedback circuit 24 are installed in parallel in the feedback loop of the recording equalizer amplifier 22, and their output j signals are sent from a terminal 26 by a switch circuit 25. Based on the mode switching signal, only one of them is selectively output and fed back to the recording equalizer amplifier 22.

When the output signal of the A-mode feedback circuit 23 is fed back, the input wave number division multiplexed signal is given a low-frequency emphasis characteristic as shown by the solid line ■ in FIG. 4(A) and FIG. and is output to the output terminal 16. On the other hand, when the output signal of the B-mode feedback circuit 24 is fed back, the input frequency-divided signals are all lower side band waves of the B-mode FMi degree signal Y'e, as shown in FIG. 4(B). The signal is outputted to the output terminal 16 with the level enhanced across the band and with a low-frequency emphasis characteristic that makes the emphasis ♀ smaller than in the A mode.

FIGS. 6(A) and 6(B) respectively show circuit diagrams of a third embodiment and a modification thereof of the essential parts of the apparatus of the present invention.

In FIGS. 6(A) and 6(B), the same components as in FIG. 1 are given the same reference numerals. In FIG. 6 (A>), the recording equalizer 7 block 28 is shown as a solid line in FIG.
It has the recording current vs. frequency characteristic of the standard image quality mode (A mode) as shown in Figure (A), and the switch circuit 32
is turned on only in high image quality mode (B mode) by a switching signal from terminal 33.

As a result, in high image quality mode (B mode), the resistor 29
．． By the circuit consisting of the coil 30 and the resistor 31, the input frequency υl multiplexed signal is relatively amplified by comparing the high frequency to the low frequency and is supplied to the recording equalizer amplifier 28, so that the output terminal 16 at this time is The FM luminance signal Y8 in the output frequency division multiplexed signal to the standard definition mode (A
The emphasis of the lower sideband wave is smaller than in the case of (mode).

Furthermore, the recording equalizer amplifier 35 shown in FIG. 6(B) has the characteristics shown by the dashed line ■ in FIG. 2, or the characteristics shown in FIG.
The switch circuit 39 is turned on only in the standard picture quality mode (A mode) by switching from the terminal 40 (+m signal).

As a result, in standard image quality mode (A mode), the resistor 3
6. By a circuit consisting of a capacitor 37 and a resistor 38,
Since the input frequency v1 multiplexed signal is relatively attenuated by comparing the high frequency to the low frequency and is supplied to the recording equalization amplifier 35, the FM in the output frequency division multiplexed signal to the output terminal 16 at this time is The luminance signal YA is in high image quality mode (
The emphasis m of the lower sideband is greater than in B mode),
As a whole, the characteristics shown in the solid line (■) in FIG. 2 (or in FIG. 4) are given.

Furthermore, 0′! In FIGS. 6 (Δ) and (B), the high acid emphasizing circuit and the low frequency emphasizing circuit may be provided on the output side of the recording equalizer amplifier 28.35.

Next, a fourth embodiment of the device of the present invention will be described with reference to the block system diagram shown in FIG. In the figure, the same components as in FIG. 1 are given the same reference numerals. The frequency division multiplexed signal from the input terminal 5 is supplied to the adder circuit 42, while passing through a low-pass filter 43 and a level adjuster 44, respectively.
is supplied to

As a result, the adder circuit 42 outputs a frequency division multiplexed signal in which the low frequency components of the passband of the low-pass filter 43 are emphasized.

Here, the upper limit cutoff frequency of the low-pass filter 43 is, for example, 3.4 MHz, and the level adjustment 8 by the level adjuster 44 is performed in accordance with the mode switching signal from the input terminal 45 in the high image quality mode (B mode). Standard image quality mode (A
By attenuating the output signal of the low-pass filter 43 more than in the standard image quality mode (A mode), the characteristics shown by the dashed line ■ in Fig. 2 can be obtained in the high image quality mode (B mode). ) In some cases, characteristics such as those shown by the solid line ■ in FIG. 2 can be obtained.

Note that in each of the above embodiments, high image quality mode (B mode)
Although it has been explained that the lower sideband is emphasized in the case of , the lower sideband may not be emphasized at all.

Note that the present invention is not limited to the above embodiments, and the frequency modulated video signal is not limited to the FM luminance signal, but also the FM luminance signal.
An M composite color video signal may also be used. Furthermore, the present invention can be similarly applied to three or more types of modes.

Effects of the Invention As described above, according to the present invention, the higher the carrier frequency of a frequency modulated video signal, the lower the level emphasis ω of its upper sideband, which is 6 extremely higher than each level of the carrier wave and upper sideband. Therefore, it is possible to prevent the occurrence of the reversal phenomenon, and especially when using a high-performance recording medium that can obtain playback output higher than the required level up to high frequencies, it is possible to prevent the occurrence of the reversal phenomenon. Even if the carrier frequency of the video signal is increased to near the limit of the recording/reproduction band of a high-performance recording medium, the inversion phenomenon is unlikely to occur, and the recording can be performed in such a way that a high-resolution reproduction image can be obtained satisfactorily. It is.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the device of the present invention, FIG. 2 is a diagram showing an example of the recording current vs. frequency characteristic provided by the device of the present invention, and FIG. FIG. 4 is a diagram showing another example of the recording current vs. frequency characteristic provided by the device of the present invention, and FIG. 5 is a diagram showing the image recorded by the device of the present invention. & Figures 6 (A) and (B) showing the frequency spectrum of the signal
7 is a circuit system diagram showing a third embodiment of the main part of the device of the present invention and a modification thereof, FIG. 7 is a block system diagram showing a fourth embodiment of the main part of the device of the invention, and FIG. 8 is a general circuit diagram. FIG. 3 is a diagram showing an example of reproduction output versus frequency characteristics in magnetic recording and reproduction. 1... Luminance signal input terminal, 2... FM modulation problem, 3
...low frequency conversion carrier color signal input terminal, 4...addition circuit, 6゜22.28.35...recording equalizer amplifier,
13... Swing circuit, 15... Feedback circuit, 23... Feedback circuit for A mode, 24...
...Feedback circuit for B mode, 44...Level adjuster. Patent Applicant Victor Company of Japan Co., Ltd. Figure 1 Figure 4 @ Figure 5 Unaccounted for, (Mse)

Claims (1)

[Claims] Frequency modulated video signals have different carrier frequencies n
A video signal recording device that records on a recording medium by switching to any one mode among n types of modes (where n is an integer of 2 or more), and which records a frequency modulated video signal in the n types of modes. The level of at least a part of the sideband is recorded while being emphasized relatively compared to the level of its carrier wave and the upper sideband, and the higher the carrier frequency of the frequency modulated video signal, the higher the level emphasis of the lower sideband. A video signal recording device characterized in that the video signal is recorded on a recording medium by setting the video signal to a small value.