JPH05292541A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a VTR which leaves the high-band component of a color signal interleaved in the spectrum of a luminance signal and FM-records this component together with the luminance signal and has a wide band of the color signal and is compatible with a conventional VTR. CONSTITUTION:A BPF 3 is provided which approximates the band which a low band conversion system has, and the color signal obtained by YC separation has the band limited by the BPF 3 and is subtracted from the original color video signal by an adder 5. Thus, the high-band component of the color signal which cannot be transmitted by the low band conversion system is added to the luminance signal and is subjected to FM modulation and is recorded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal recording / reproducing apparatus such as a VTR for converting a color signal into a low frequency band to record / reproduce the video signal.

[0002]

2. Description of the Related Art A system called a low-frequency conversion system is widely used as a recording / reproducing system for a domestic VTR color signal.
This is 3. when recording NTSC color video signals.
This is a method of frequency-converting (low-frequency conversion) a color signal in the vicinity of 58 MHz into a low frequency of about 600 kHz, and then frequency-multiplexing it with an FM-modulated luminance signal for recording, which is very difficult to reduce tape consumption. It is an efficient method.

[0003]

By the way, since the low frequency conversion method once converts to a low frequency, it is difficult to widen the band of the color signal. That is, if the carrier is selected to be about 600 kHz, the color signal band will be about 0.5 MHz.
Since only about ⅓ of 1.5 MHz transmitted by the SC color signal can be recorded, the image quality is greatly deteriorated. If the frequency of the carrier is changed to a higher value, the recordable color band increases, but the frequency band of the brightness signal decreases due to frequency-multiplexed recording with the FM-modulated brightness signal. You lose compatibility.

According to the present invention, the high frequency component of the color signal is interleaved in the spectrum of the luminance signal and is FM-recorded together with the luminance signal so that the band of the color signal is wide.
It is intended to provide a VTR compatible with.

[0005]

According to the present invention, at the time of recording, a high frequency component of a color signal which is not recorded by recording by low frequency conversion is left in the spectrum of the luminance signal and an FM modulation system similar to the luminance signal is used. And record.

Further, the low frequency component of the color signal is frequency-converted into the low frequency and recorded as in the conventional VTR.

[0007]

When reproducing, the high frequency component of the color signal transmitted between the spectra of the luminance signal is added to the low frequency component of the color signal transmitted from the low frequency conversion system to reproduce the color signal having a wide band. Is possible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a recording / reproducing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a recording / reproducing apparatus of the present invention, and FIG. 2 shows a frequency spectrum of a signal of each section.

In FIG. 1, the video signal having the frequency spectrum shown in FIG.
Color signals that are input to the C separation circuit 2 and have the frequency spectrum shown in FIG. 2B are separated. In FIG. 2, the horizontal axis represents frequency and the vertical axis represents the spectrum level of the video signal. When the video signal is an NTSC color video signal, the center is around 3.58 MHz as shown in the figure. The YC separation circuit 2 may use an ordinary comb filter composed of a glass delay line or the like.

Further, the separated color signals are frequency-converted into a low frequency band by the frequency conversion circuit 4 in the same manner as a color VTR of a normal low frequency band conversion system.

The output of the other YC separation circuit 2 passes through a bandpass filter (BPF) 3 having a phase and frequency characteristic equivalent to the recording / reproducing characteristic in the band of the low frequency conversion system, and then the original composite image. The signal is subtracted from the signal by the subtractor 5 to obtain the frequency spectrum shown in FIG. 2C. As a result, the high-frequency component of the color signal that cannot be sent by the low-frequency conversion system remains in the luminance signal, is FM-modulated by the FM-system signal processing circuit 6 as a luminance signal, and is then low-frequency converted. The color signals are added by the adder 7 to obtain the frequency spectrum shown in FIG. 2D, which is recorded on the tape by the RF recording system signal processing circuit 8. Home VT such as VHS and 8mm video
In R, in order to secure the SNR of high frequency components at the time of FM modulation,
In order to emphasize high-frequency components called emphasis and reduce crosstalk from adjacent tracks of color signals, PS,
It is common to use a method called the PI recording method, and even if this method is used, the effect of the present invention does not change.

FIG. 3 shows a block diagram on the reproducing side when the recording shown in FIG. 1 is performed. The signal having the frequency spectrum shown in FIG. 2D, which is reproduced by the reproduction RF system signal processing circuit 9, is demodulated by the FM demodulation circuit 10 and the high frequency conversion circuit 11, respectively, as in the case of the normal low frequency conversion system VTR.
C and the signal having the frequency spectrum shown in FIG. 2B, and the signal having the frequency spectrum shown in FIG.

At this time, since it is necessary to accurately match the phases of the signals transmitted from both systems, the high-frequency component of the chrominance signal in the luminance signal and the chrominance signal converted into the low-frequency component are separately provided. It is necessary to use the time base collectors 13 and 14 to change the time base.

At this time, the horizontal synchronizing signal of the luminance signal is sufficient as the time axis reference, but a burst wave may be inserted in the front porch of the luminance signal. Further, the color burst originally present in the NTSC signal can be used as it is.

As described above, the low frequency component of the color signal is transmitted by the low frequency conversion transmission system, and the high frequency component is transmitted by the direct FM transmission system, so that a wide color signal band can be realized.

Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 4 shows a second recording / reproducing apparatus of the present invention.
5 is a block diagram of the embodiment of FIG. 5, and FIG. 5 shows a frequency spectrum of a signal of each part.

In FIG. 4, the video signal having the frequency spectrum shown in FIG.
The luminance signal input to the YC separation circuit 16 and having the spectrum shown in FIG. 5B is separated. Further, the separated color signals are frequency-converted into the low frequency band by the low frequency band conversion circuit 17 like the color VTR of the normal low frequency band conversion system.

Further, the C output of one YC separation circuit 16 passes through the BPF 18 assuming the band of the low frequency conversion system and becomes the spectrum shown in FIG. 5D, and then the subtractor 19 for the original color signal. And subtracted to obtain a signal having the frequency spectrum shown in FIG. 5C. This is the high frequency component of the color signal that is not normally transmitted in the low frequency conversion color signal transmission system. This high-frequency component is further inverted in phase for each field by a switching circuit 21 for switching between inversion / non-inversion for each field, and the luminance signal component separated by the YC separation circuit 16 and the adder 20. Is added. As a result, the high frequency components of the color signal are interleaved in the luminance signal. Therefore, the high frequency component of the color signal that cannot be sent by the low frequency conversion system becomes a color signal of opposite phase in the field and remains in the luminance signal.
The frequency is modulated by the FM system signal processing circuit 22, and the adder 23
Is added and recorded with the low-frequency component of the color signal that has been low-frequency converted.

The high frequency component of the color signal to be added to the luminance signal is
The level can be made higher than it was when the video signal was originally a composite video signal. Thereby, the SN ratio of the high frequency component of the color signal can be improved. This can be easily realized by adjusting the addition ratio k of the adder 20. FIG. 6 shows a block diagram on the reproducing side when the recording shown in FIG. 4 is performed.

The signal of the frequency spectrum shown in FIG. 5F reproduced by the RF reproduction system signal processing circuit 24 is input to the high frequency conversion circuit 25 as in the case of the normal low frequency conversion system VTR, and becomes the spectrum of FIG. 5D. Is played. This is the low frequency component of the color signal. Further, the luminance signal including the high frequency band of the color signal demodulated by the FM demodulation circuit 26 is the YC separation circuit 2
In FIG. 7, the luminance signal and the chrominance signal of the high frequency component of the wavenumber spectrum shown in FIGS. 5B and 5E are separated.

Further, the high-frequency component of the color signal is inverted in phase for each field by the phase inversion circuit 28 to be a signal of the spectrum shown in FIG. Is added to the luminance signal together with the low frequency component of the color signal.

As a result, the high-frequency components of the color signal are included in FIG.
The original signal shown in A is reproduced. As in the first embodiment, since it is necessary to accurately match the phases of the signals,
A time base collector 30 is separately provided for each of the high-frequency component and the low-frequency component of the color signal in the luminance signal.
It is necessary to use 31 to take the time base fluctuation.

The reproducing circuit of FIG. 6 has a phase inverting circuit 28. However, when the recorded tape of FIG. 4 is reproduced using a conventional VTR having no phase inversion circuit 28,
Even if the high-frequency component of the color signal has its phase inverted in each field and is demodulated as a color, it becomes an opposite phase color for each field, which does not cause visual interference.

[0024]

As described above, according to the present invention, the low frequency component of the chrominance signal is frequency-converted into the low frequency region and AM recorded as in the conventional case, and the high frequency component of the chrominance signal is the same as the luminance signal of the normal composite signal. By interleaving between frequency spectra and performing FM recording together with the luminance signal, the band of the color signal can be easily widened in the VTR of the low frequency conversion system. Further, it is compatible with the conventional recording / reproducing apparatus of the low frequency conversion system, and when the tape containing the high frequency components of the color signals recorded by this system is reproduced by the conventional VTR, it does not cause a great disturbance.

[Brief description of drawings]

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

2A is a frequency spectrum diagram of a video signal input to the recording / reproducing apparatus of the present embodiment, FIG. 2B is a frequency spectrum diagram of a color signal separated by a YC separation circuit, and FIG. 2C is an output of a subtractor. Frequency spectrum diagram of signal (D) Frequency spectrum diagram of output signal of adder

FIG. 3 is a block diagram of a reproducing unit of the recording / reproducing apparatus of this embodiment.

FIG. 4 is a block diagram showing another embodiment of the recording / reproducing apparatus of the present invention.

FIG. 5A is a frequency spectrum diagram of a video signal input to the recording / reproducing apparatus of this embodiment. FIG. 5B is a frequency spectrum diagram of a luminance signal separated by a YC separation circuit. (D) is the frequency spectrum diagram of the color signal output from the BPF. (E) is the frequency spectrum diagram of the phase-inverted high frequency color signal. Output signal frequency spectrum diagram

FIG. 6 is a block diagram of the reproducing unit.

[Explanation of symbols]

 2 YC separation circuit 3 band pass filter 4 low frequency conversion circuit 5 adder 6 FM system signal processing circuit 7 adder 9 RF recording system signal processing circuit 10 FM demodulation circuit 11 high frequency conversion circuit 21 field unit phase inversion circuit

Claims (6)

[Claims] 1. In a recording / reproducing apparatus for frequency-converting a color signal of a composite color video signal into a low frequency range and frequency-multiplexing with an FM-modulated luminance signal, a high-frequency component of a color signal which is not transmitted by low frequency conversion. And a video signal recording / reproducing apparatus, wherein the video signal is multiplexed and recorded with the luminance signal. 2. A recording / reproducing apparatus for a video signal according to claim 1, wherein when the high frequency component of the color signal is multiplexed with the luminance signal, the phase is inverted by 180 degrees for each field for recording. 3. A video signal recording / reproducing apparatus according to claim 1, wherein when the high frequency component of the chrominance signal is multiplexed with the luminance signal, the recording is performed while increasing the level. 4. A high-frequency component of a chrominance signal obtained by subtracting a chrominance signal that has passed through a band-pass filter equivalent to a recording / reproducing characteristic of a transmission system for low-pass conversion from an original chrominance signal into a luminance signal. 4. The video signal recording / reproducing apparatus according to claim 1, wherein the video signal recording / reproducing apparatus is multiplexed. 5. At the time of reproduction, the reproduced low frequency color signal and the demodulated luminance signal are subjected to time base variation by using a time base collector, and then the color signal is converted to a high frequency range and added to the luminance signal. The video signal recording / reproducing apparatus according to any one of claims 1 to 4, wherein 6. The image according to claim 1, wherein a burst wave is inserted into the front porch of the luminance signal, and the time axis fluctuation is removed by using the burst wave during reproduction. Signal recording / reproducing device.