JPS62198284A - Video signal recording and reproducing system for video tape recorder - Google Patents

Abstract

PURPOSE:To increase the information transmission quantity of a luminance signal and to improve the resolution of a reproduced video signal by filling up a gap on a transmission of the luminance signal existing in a frequency band between integer multiples of a horizontal frequency, with other information. CONSTITUTION:A luminance signal in a base band has a strong correlativity in the vertical direction on a screen. Accordingly, a luminance signal spectrum concentrates in an integer multiple of a horizontal synchronizing frequency fH. On the contrary, a signal which enters between integer multiples of fH of the luminance signal spectrum becomes a noise component which cannot constitute a picture element extending over a wide range on the screen. Accordingly, a gap exists in a frequency band which is between integer multiples of fH in a transmission of the luminance signal, and this gap is filled up by a low band conversion high band luminance signal component which has brought a high band frequency component of the luminance signal to a low band conversion, by which an information transmission of density of the maximum 2 times of a conventional luminance signal can be executed without raising a carrier- frequency of the luminance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a video signal recording and reproducing method for a video tape recorder that improves the transmission video signal density of the video tape recorder.

[Technical Background of the Invention] Conventionally, the horizontal resolution of television receivers was about 250 lines, but in recent years, high-resolution television receivers with a horizontal resolution of about 500 lines have become popular.

For this reason, conventional home video tape recorders (VTRs)
> The information density of the video signal is insufficient for the above-mentioned high-resolution television receiver, and a situation has arisen in which the original performance of the high-resolution television receiver cannot be demonstrated.

Therefore, in 1/2-inch home VTRs that use the Beta format, the brightness FM
By increasing the carrier frequency of the signal to 800 MHz, the transmission band of the luminance FM signal is widened, and the information contained in the luminance signal is increased in density.
This allows you to obtain high-resolution images.

[Problems with the Background Art] However, as described above, if the carrier frequency of the luminance FM signal is increased to increase the information density of the luminance signal, this broadband luminance FM signal will be reduced to 1! ! There is less margin on the high frequency side of the frequency characteristics of the reproduced luminance FM signal until a peculiar phenomenon called inversion occurs when adjusting the brightness, and deterioration of image quality due to the inversion phenomenon becomes a problem. Therefore, since the broadening of the luminance FM signal is also done taking this inversion phenomenon into consideration, VT
It has been difficult to dramatically improve the resolution of R.

In addition, in home VTRs that use the VH3 system, which is one of the 17'2 formats, the relative speed of the video head with respect to the magnetic tape is slower than that of the Beta system described above, so it is possible to increase the brightness by increasing the carrier frequency of the brightness FM signal. There is a problem in that it is particularly difficult to widen the band of FM signals.

[Object of the Invention] In view of the above-mentioned drawbacks, it is an object of the present invention to improve the resolution of reproduced video signals without widening the transmission bandwidth of the current luminance signal and while maintaining compatibility with conventional video signals. It is an object of the present invention to provide a video signal transmission system for a video tape recorder that can be used in a video tape recorder.

[Summary of the Invention] The present invention focuses on the fact that information transmission ports for luminance signals can be increased by filling gaps in luminance signal transmission that exist in frequency bands between integral multiples of the horizontal frequency with other information. death,
The high-frequency luminance signal component of the luminance signal is separated and low-frequency converted, and the low-frequency converted high-frequency luminance signal component is added to the low-frequency luminance signal component of the original luminance signal to obtain a recording luminance signal, and the above-mentioned A low-frequency converted high-frequency luminance signal component is extracted from the reproduced luminance signal obtained by reproducing the luminance signal recorded as shown in FIG. By adding the low 1tii 1 degree signal component of the original reproduced luminance signal to obtain the final reproduced luminance signal, it is possible to maintain compatibility with the conventional luminance signal without expanding the transmission bandwidth of the current luminance signal. This is to achieve the purpose of improving the resolution of video signals that are magnetically recorded and reproduced.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
FIG. 1 is a block diagram showing an embodiment of a recording system of a video signal recording and reproducing method of a video tape recorder according to the present invention. 1
is the input composite video signal 100 for one horizontal scanning period (1
H) A one-day delay circuit, 2 is an adder that adds the original composite video signal 100 to the composite video signal delayed by one horizontal scanning period and removes the color signal component, and 3 is the input luminance signal. 4 is a low-pass filter that extracts a low-band luminance signal component 300 from the input luminance signal 200; 4 is a band-pass filter that extracts a high-band luminance signal component 401 from the input luminance signal 200; 5;
6 is a balanced modulator that converts the high frequency luminance signal component 401 into a low frequency luminance signal using a reference signal having a constant frequency supplied from the voltage controlled oscillator 8; 6 is a low frequency converted signal component from the balanced modulator 5; 7 is an adder that adds the low-pass converted high-frequency luminance signal component 402 to the low-pass luminance signal component 300; Balanced modulator 5
a voltage controlled oscillator that outputs a constant frequency reference signal to
10 is a horizontal synchronization separation circuit that separates a horizontal synchronization signal from a composite video signal 100, and 10 is a horizontal synchronization signal separated by 1/2.
11 is a frequency divider that divides the oscillation signal of the voltage controlled oscillator 8, and 12 is a horizontal synchronization signal obtained from the frequency divider 10 and whose frequency is divided to 1/2. , a phase comparison circuit which inputs the frequency-divided oscillation signal from the voltage controlled oscillator obtained from the frequency divider 11 and compares the phases of the two, and 13 removes unnecessary parts from the phase comparison result of the phase comparison circuit 12. A low-pass filter is supplied to the voltage controlled oscillator 8; 14 is a brightness signal modulation circuit that performs FM modulation on a brightness signal obtained by combining the low-band brightness signal component 300 and the low-band converted high-band brightness signal component 402; An adder adds the FM modulated luminance signal 500 and a separately obtained low frequency conversion color signal 600 to synthesize a recorded video signal; 16 is a recording head for recording the recorded composite video signal on a tape (not shown); 30 is a low frequency converter; This is a delay line that performs time alignment between the range luminance signal component 300 and the low-range converted high-range luminance signal component/102.

Next, the operation of this embodiment will be explained. First, before going into the description of the embodiments, the principle of the present invention will be explained. Luminance signals in the baseband have a strong correlation in the vertical direction on the screen. In other words, the correlation after one horizontal scanning period is strong. Therefore, the luminance signal spectrum is concentrated at integral multiples of the horizontal synchronization frequency (hereinafter referred to as f). Conversely, a signal that falls between integral multiples of fH in the luminance signal spectrum spreads over a wide range on the screen and becomes a noise component that does not constitute a pixel. Therefore, due to the above relationship, a gap exists in the frequency band between integral multiples of fH in the transmission of the luminance signal, and this gap is converted into a low-frequency converted high-frequency luminance signal component obtained by converting the high-frequency component of the luminance signal to a low frequency band. By filling it with , it is possible to transmit information with a density up to twice that of a conventional luminance signal without increasing the carrier frequency of the luminance signal.

By the way, Fig. 2 (A) is an example showing the frequency spectrum of the low-range luminance signal component, and the luminance signal spectrum is concentrated at integral multiples of fH. Fig. 2 (B) shows the frequency spectrum of the low-range luminance signal component. This is an example showing the luminance signal spectrum of the low-frequency luminance signal component, and when converting to low-frequency range, the frequency spectrum is such that it is concentrated in the gap in the frequency spectrum of the low-frequency luminance signal, and when the two are added, the low-frequency luminance signal can be obtained. A low-frequency converted high-frequency luminance signal is inserted into the gap, and the information density of the obtained luminance signal can be improved.

Next, an explanation will be given of an embodiment showing a recording system of a VTR that realizes the principle of the above invention. The composite video signal 100 is added in an adder 2 to a degree video signal delayed by 1H from a 1H delay line 1 made of a glass delay line, etc., and becomes a luminance signal @200 from which the 3.58MH2 subcarrier color signal is removed. . This luminance signal 200 becomes a low-frequency luminance signal component 300 from which high-frequency components are removed by a low-pass filter (approximately 3MH1), which is further delayed by a delay line 30 and then input to an adder 7.

At the same time, this luminance signal @200 is input to a band pass filter 4 of about 3 to 4M87, where the high frequency luminance signal component 4
01 and is input to the balanced modulator 5. In the balanced modulator 5, the high frequency luminance signal component 401 inputted thereto is converted to a low frequency by the reference signal given from the voltage controlled oscillator 8. The low-pass filter 6 removes unnecessary components from this low-frequency converted component, and the desired low-frequency converted high-frequency luminance signal component 402 is inputted to the adder 7 . Here, FIG. 3(A) shows the frequency characteristics of the luminance signal 200, FIG. 3(B) shows the frequency characteristics of the low-range brightness signal component 300, and FIG. 3(C) shows the frequency characteristics of the high-range brightness signal component 401. shows the frequency characteristics of

Therefore, in the adder 7, as shown in FIG. The result is sent to the luminance signal modulation circuit 14 as FM
It is modulated and becomes an FM modulated luminance signal 500, which is sent to the adder 15.
is input. The adder 15 adds the separately generated low frequency conversion color signal 600 and the FM modulated luminance signal 500 to form a recording video signal, which is recorded by the head 16 onto a tape (not shown).

On the other hand, the oscillation signal of the voltage controlled oscillator 8 is frequency-divided by a frequency divider 11 and then input to a phase comparator circuit 12 .

A signal obtained by dividing the horizontal synchronization signal separated by the horizontal synchronization separation circuit 9 from the composite video signal 100 to 1/2 frequency by the frequency divider 10 is input to the phase comparison circuit 12. A phase comparison between the frequency-divided signal of the voltage-controlled oscillator 1 and this horizontal synchronizing signal is performed in the phase comparison circuit 12, and the result is fed back to the voltage-controlled oscillator 8 via the low-pass filter 13. As a result, the reference signal supplied by the voltage controlled oscillator 8 to the balanced modulator 5 becomes a phase-locked signal having a constant frequency. Here, if the oscillation frequency of the voltage controlled oscillator 8 is fvco, this fvco is set so as to satisfy the following relational expression.

f = (2(n+1＞/2)fH””(1)VC
O (f −f ><f <f...
-(2) 2 1 VCO1 However, fl and f2 are the cutoff frequencies of bandpass filter 4 (fl x f2). As a result, fVCO is 2
A suitable frequency is around M1-IZ.

FIG. 4 is a block diagram showing an embodiment of the reproduction system of the video signal recording and reproduction method of the video tape recorder of the present invention. Playback video signal 70 played back by playback head 17
After being amplified by the preamplifier 18, the U luminance signal 800 is input to the luminance signal/chrominance signal separation circuit 19, where it is separated into a luminance signal B00 and a low frequency converted color signal 900.
is input to the luminance signal demodulation circuit 20 and demodulated there, and then becomes a low-frequency luminance signal component 1000 with high-frequency components cut by the low-pass filter 21. This low-band luminance signal component 1000 is delayed by 1H by a broadband 1H delay line 22 such as a charge-coupled device, and then subtracted by a subtracter 23 from the original low-band luminance signal component 1000 that is not delayed by 1H. Signal components without 1H correlation are extracted from . Unnecessary components are removed from this component by the bandpass filter 24, resulting in a low-frequency converted high-frequency luminance signal component 1100. This low-frequency converted high-frequency luminance signal component 1io
o is frequency-converted by the balanced modulator 25 into the original high-band luminance signal component 1200 based on the reference signal from the voltage controlled oscillator 26 supplied to this modulator, and is output to the adder 27. The adder 27 receives 1000 low-range luminance signal components.
is delayed by the delay line 28, and the high-frequency luminance signal component 12
00 and is inputted, and a reproduced luminance signal 1300 is created in which the low-frequency converted luminance signal component 1000 and the high-frequency luminance signal component 1200 are synthesized. This reproduced luminance signal 1300 is added to the sub-carrier color signal 1400 created by processing the low frequency conversion color signal 900 in an adder 29, and a reproduced composite video signal is synthesized and outputted from the adder 29.

Note that the voltage controlled oscillator 26 is the same as the voltage controlled oscillator in the recording system shown in FIG. The same frequency is supplied to the balanced modulator 25. At this time, jitter components included in the VTR mechanical system are also removed by the phase-locked loop controlling the voltage controlled oscillator 26. In addition, only the main parts of the circuits shown in Figures 1 and 4 are shown, and the actual circuits include a high-frequency emphasis recording circuit for the purpose of noise reduction, a high-frequency control circuit that restores the original state during playback, and Various frequency characteristic correction circuits and the like are provided.

Further, the circuit of the 1H delay line 22 and subtracter 23 shown in FIG. 4 may be used in common with the comb filter in a VTR equipped with a luminance signal circular filter.

According to this embodiment, a luminance signal synthesized from a high-frequency luminance signal component 401 as a low-frequency converted high-frequency luminance signal component 402 with respect to a low-frequency luminance signal component 300 of the original luminance signal is recorded, and at the time of reproduction, a luminance signal is recorded. Low-frequency conversion from luminance signal High-frequency luminance signal component 11
00 is extracted and frequency-converted to the original high-frequency luminance signal component, and then the low-frequency luminance signal component 100 of the reproduced luminance signal is extracted.
By adding it to 0 to obtain the reproduced luminance signal 1300,
It is possible to substantially increase the band of the luminance signal by 1 MH2 or more without increasing the carrier frequency of the i-degree signal, thereby increasing the amount of transmitted information and improving the resolution of the screen. Furthermore, since the carrier frequency of the luminance signal remains the same, even when a tape recorded using this method is played back on a conventional VTR, no inversion occurs and compatibility with the conventional method can be maintained. In particular, this system can easily increase the resolution of VH3 system VTRs in which the relative speed of the tape and video head is slower than that of the Beta system.

[Effects of the Invention] As described above, according to the video signal recording and reproducing method of the video tape recorder of the present invention, the high frequency component of the luminance signal is separated and converted to low frequency, and the low frequency converted high frequency luminance signal component is converted to low frequency. The recorded luminance signal is obtained by adding it to the low frequency component of the original luminance signal, and the low frequency converted high frequency luminance signal component is extracted from the reproduced luminance signal obtained by reproducing the recorded luminance signal as described above. By converting this into the original high-frequency luminance signal component, and adding this high-frequency converted luminance signal component to the low-frequency luminance signal component of the original reproduced luminance signal to obtain the final reproduced luminance signal, This has the effect of improving the resolution of video signals that are magnetically recorded and reproduced without widening the current transmission bandwidth of luminance signals and maintaining compatibility with conventional models.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a recording system to which the video signal recording and reproducing method of a video tape recorder of the present invention is applied; FIG. 2 is a frequency spectrum of a luminance signal that explains the principle of this defense; The figure is a waveform diagram explaining the luminance signal processing process shown in the circuit shown in Figure 1, and Figure 4 shows an embodiment of a playback system to which the video signal recording and playback method of the video tape recorder of the present invention is applied. It is a block diagram. 1, 22...1H delay line 2, 7.15.27.29...Adder 3...Low pass filter 4...Band pass filter 5.25...
・Balanced modulator 8, 26...voltage controlled oscillator 14・
... Brightness signal modulation circuit 20 ... Brightness signal demodulation circuit 2
3. Kuzukasen Agent Patent Attorney Nori Chika Ken Shu Canshu Uji HiroshiFigure 2Figure 3

Claims (1)

[Claims] 1) The luminance signal is separated into a high-frequency luminance signal component and a low-frequency luminance signal component, and the high-frequency luminance signal component is divided into a low-frequency luminance signal component such that the horizontal frequency is interleaf with the low-frequency luminance signal component. 1. A video signal recording system for a video tape recorder, characterized in that a recorded luminance signal is obtained by converting the low-frequency converted high-frequency luminance signal component to the low-frequency luminance signal component. 2) Extract the low-frequency converted high-frequency luminance signal component from the reproduced luminance signal reproduced from the head, convert it into the original high-frequency luminance signal component, and convert this high-frequency luminance signal component into the reproduced luminance signal. A video signal recording and reproducing method for a video tape recorder, characterized in that a final reproduced luminance signal is obtained by combining the lower frequency luminance signal components of