JPH0683480B2 - Color video signal transmission method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting a color video signal from a color video signal transmission device such as a video tape recorder to a color video signal reception device such as a color television.

2. Description of the Related Art VTRs and color televisions (abbreviated as CTV) are used in the field of sucking conventional consumer video tape recorders (abbreviated as VTR).
A composite video signal in which a luminance signal and a carrier color signal are frequency-multiplexed is used for transmission of a color video signal between the base band (base band) and the broadcast wave band (RF band). For example, VTR and so-called AV system T as described in Broadcasting Technology Magazine, August 1983, pages 59-71.
VTR video (video) for transmitting color video signals with V
The baseband signal of the NTSC composite video signal is transmitted from the output terminal and received by the video input terminal of the AV system TV, which affects the baseband transmission. Such a VTR
It can be said that the baseband transmission of the composite video signal between the CTV and the CTV is an excellent transmission method compared to the transmission in the broadcast wave band, because the composite video signal is less deteriorated as much as it does not pass through the RF converter and the filter.

However, for example, V in an NTSC type consumer VTR
In the HS standard, the β standard, or the 8 mm VTR standard, the luminance signal and the chrominance signal are recorded separately, but as the output signal from the VTR, a composite video signal in which the luminance signal and the carrier color signal are frequency-multiplexed is output, Extra operations such as frequency multiplexing and frequency separation are performed in which the signals are transmitted to the CTV and frequency-separated again into a luminance signal and a carrier color signal by using a comb filter in the CTV. That is, in the frequency multiplexing and frequency separation of the luminance signal and the carrier color signal, the amplitude and phase information of the transmission signal is lost due to the imperfections of the filter and the amplifier, and further the circuit noise is added to deteriorate the quality of the transmission signal. Have a point

Hereinafter, an example of a method of transmitting a color video signal as a composite video signal between the above-described VTR and CTV will be described with reference to the drawings. FIG. 3 is a block diagram of a main part of an example of a conventional color video signal transmission system between a VTR and a CTV. In FIG. 3, a luminance signal and a color signal recorded or reproduced in the VTR are output to the output terminals 2, 3 and 4 of the VTR color video signal processing circuit 1, respectively. Third
In the figure, a luminance signal (Y signal, Y signal in FIG. 2 (a)) is output from the output terminal 2, and color signals (I signal, Q signal, I, Q signals in FIG. 2 (b) are output from the output terminals 3 and 4. ) Are output respectively. These Y, I and Q signals are respectively low pass filter 1 (abbreviated as LPF1), LPF3 and LPF.
5, the respective outputs are band-limited as shown by Y ₁ , I ₁ and Q ₁ in FIGS. 2 (c) and 2 (d). The band limits for the Y, I and Q signals in the NTSC standard are 4.2MHz, 1.5MHz and 0.5MHz respectively. LPF3 and LPF
The I ₁ and Q ₁ signals, which are the output signals of 5, are quadrature two-phase modulators 11
In this case, the carrier suppression quadrature two-phase amplitude modulation is performed by the 3.579545 MHz sub-carrier and becomes the K signal in FIG. 2 (g), which is the output signal of the LPF1 in the Y / C mixing circuit 13 in FIG. 2 (c).
It is frequency-multiplexed with the Y ₁ signal to form a composite video signal shown in FIG. When the transmission of the composite video signal from the VTR to the CTV is in the base band, the output of the Y / C mixing circuit is the output terminal 15 of the VTR.
Output from the CTV input terminal 19 and Y / C in the CTV
It reaches the separation circuit 24. Also, when the transmission of the composite video signal from the VTR to the CTV is in the broadcast wave band, the output of the Y / C mixing circuit is modulated in the broadcast band by the RF modulator 14 and is output from the VTR output terminal 16 to the CTV input terminal. At 20, the RF demodulator 23 demodulates the mixed video signal in the base band again and reaches the Y / C separation circuit in the CTV. In the Y / C separation circuit, the composite video signal shown in FIG. 2 (h) is converted into a luminance signal (for example, as shown in FIG. 2 (c)).
Y ₁ ) and the carrier color signal (for example, K in FIG. 2 (g)) are frequency-separated and input to the input terminals 33 and 34 of the TV color video signal processing circuit 35, respectively.

Problems to be Solved by the Invention Transmission of a color video signal between a conventional VTR and a CTV is performed in the form of an NTSC composite video signal which is a standard television signal in which a luminance signal and a carrier color signal are frequency-multiplexed as described above. Since it is transmitted, the amplitude and phase information of the transmission signal is damaged due to the incompleteness of the filter and the amplifier in the frequency multiplexing of the luminance signal and the carrier color signal on the VTR side or the frequency separation on the TV side, causing waveform distortion, There is a big problem that the quality of the transmission signal is deteriorated due to the addition of circuit noise.

In addition, for example, in the NTSC system, the luminance signal and the carrier color signal are frequency-multiplexed due to the frequency interleaving relationship, and cross color or cross luminance due to mutual interference between the luminance signal and the color signal gives noise to the image quality. There is a problem that the adverse effect is great.

Furthermore, in the NTSC system, the bandwidth of the luminance signal is 4.2MHz, and the bandwidth of the chrominance signal is 1.5M for the I and Q signals respectively.
Since it is decided to be Hz and 0.5MHz, it is natural that NT
It cannot transmit luminance signals and chrominance signals in a wider band than that specified by the SC system standard.

In view of the above problems, the present invention is a wide band and high quality luminance signal and carrier chrominance signal in a wider band than in the case of handling an NTSC standard signal by a simple addition change of an output circuit system of a VTR handling an NTSC signal and an input circuit system of a CTV. It is intended to provide a transmission method that enables easy transmission between a VTR and a TV.

Means for Solving the Problems In order to solve the above problems, in the present invention, for example, a synchronizing signal such as a vertical synchronizing signal and a horizontal synchronizing signal at the same timing as the NTSC composite video signal is provided, and a luminance signal of the NTSC signal. The high-quality luminance signal and carrier color signal are separated in a wider band than the color signal and output from the VTR and transmitted to the CTV. In the CTV, these broadband luminance signals and carrier color signals are switched to the luminance signal output and carrier color signal output of the Y / C separation circuit, and in the color video signal processing circuit, they become wideband and high quality R, G, B signals. To be converted.

Operation In the present invention, by the above method, although it is a VTR and CTV that handle a conventional NTSC composite video signal, it is wider than that determined by the standard of NTSC system, for example, the luminance signal band is 6 MHz, and the chrominance signal band is High-quality EDTV, etc., which has an effective display screen area aspect ratio of 9:16 at 1.5 MHz, has no cross interference such as cross color or cross luminance, and has less additional noise in the circuit system. Video signals can be transmitted.

Embodiment An embodiment of the color video signal transmission method of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of essential parts in an embodiment of the present invention. In Figure 1, VT
A luminance signal and a color signal recorded or reproduced in the VTR are output to the output terminals 2, 3 and 4 of the VTR color video signal processing circuit 1 in the R, respectively. In FIG. 1, a luminance signal (Y signal in FIG. 2A) is output from the output terminal 2, and color signals (I signal and Q signal in FIG. 2B) are output from the output terminals 3 and 4, respectively. It The Y signal output from the output terminal 2 is split into two systems, one of which is an NTSC system 4.2M.
It is input to LPF1 which limits the band of Hz, and the other is input to LPF2 having a pass band of 20 MHz wider than LPF1.
The I signal output from the output terminal 3 is branched into two systems, one of which is input to the LPF 3 which limits the band of the NTSC system, and the other of which is input to the LPF 4 having a pass band wider than the LPF 3, for example, 3 MHz. The Q signal output from the output terminal 4 is branched into two systems, one of which is input to the LPF 5 which limits the band of the NTSC system, and the other is input to the LPF 6 having a pass band wider than the LPF 5, for example, 3 MHz. As a result, the outputs of LPF1, LPF3, and LPF5 become the Y ₁ signal in FIG. 2 (c), the I ₁ signal in FIG. 2 (d), and the Q ₁ signal, respectively. Also LPF2, LPF4, LPF6
2 becomes the Y ₂ signal in FIG. 2 (e), and the I ₂ signal and Q ₂ signal in FIG. 2 (f). The I ₁ signal that is the output of LPF3 and the Q ₁ signal that is the output of LPF5 are subjected to carrier suppression quadrature two-phase amplitude modulation by the subcarrier in the NTSC system in the quadrature two-phase modulator 11, and become the K signal in FIG. 2 (g). It is converted and frequency-multiplexed with the Y ₁ signal which is the output of LPF ₁ in the Y / C mixing circuit 13 to form a composite video signal shown in FIG. When the transmission of the composite video signal from the VTR to the CTV is in the base band, the output of the Y / C mixing circuit is the output terminal 15 of the VTR.
Output from the CTV input terminal 19 and Y / C in the CTV
It reaches the separation circuit 24. If the transmission of the composite video signal from the VTR to the CTV is in the broadcast wave band, the output of the Y / C mixing circuit is modulated in the broadcast wave band by the RF modulator 14 and the output terminal 16 of the VTR is used.
Further, it reaches the input terminal 20 of the CTV and is demodulated again by the RF demodulator 23 into the composite video signal in the base band to be the Y / C separation circuit in the CTV.
Up to 24. In the Y / C separation circuit, the composite video signal shown in FIG. 2 (h) is converted into the luminance signal represented by the Y ₁ signal in FIG. 2 (c) and the carrier color represented by the k signal in FIG. 2 (g). The signals are frequency-separated and input to the input terminal 26 of the switch 25 and the input terminal 30 of the switch 29, respectively.

By the way, the I ₂ signal which is the output signal of the LPF 4 and the Q ₂ signal which is the output signal of the LPF 6 are subjected to the quadrature two-phase amplitude modulation by the subcarrier in the NTSC system in the quadrature two-phase modulator 12, and the K ₂ signal in FIG. 2 (i). It is output from the output terminal 18 of the VTR, reaches the input terminal 22 of the CTV, and reaches the input terminal 31 of the switch 29 in the CTV. The Y ₂ signal, which is the output signal of LPF _2, is the output terminal 1 of the VTR.
It is output from 7 and reaches the input terminal 21 of the CTV, and the switch 2 in the CTV
5 to the input terminal 27. When outputting the Y ₁ signal to the output terminal 28 of the switch 25, the input terminal 26 and the output terminal 28 are conducted, and when outputting the Y ₂ signal, the input terminal 27 and the output terminal 28 are connected.
And conduct. When outputting the K signal to the output terminal 32 of the switch 29, the input terminal 30 and the output terminal 32 are electrically connected,
When outputting the K ₂ signal, the input terminal 31 and the output terminal 32 are electrically connected. The two output terminals 28 and 32 of the switch 25 and the switch 29 are respectively a TV color video signal processing circuit 35.
Connected to input terminals 33 and 34 of. Ie switch
In 25 and 29, the luminance signal and the carrier color signal input to the TV color video signal processing circuit can be switched. That is, it is possible to input a luminance signal and a carrier color signal having a wider band than that of the NTSC standard signal to the TV color image processing circuit. Now
Since the broadband carrier color signal input from the input terminal 34 of the TV color image processing circuit 35 is also modulated by the NTSC subcarrier, the I ₂ signal and the Q ₂ signal or the RY signal having the 3 MHz band and It is easy to demodulate into a BY signal or the like. By controlling the pass band of the filter of the carrier chrominance signal demodulation circuit with I ₁ signal, Q ₁ signal, I ₂ signal and Q ₂ signal, etc., a color difference signal with a good signal-to-noise ratio can be obtained, resulting in high quality in a wide band. RGB signals can be obtained.

As described in detail above, in the transmission of a color video signal between an NTSC VTR and a CTV, it is possible to easily transmit a high-quality luminance signal and color signal in a wider band than the NTSC standard.

In the embodiments, the VTR is used as the transmission source of the broadband luminance signal and the chrominance signal, and the CTV is used as the receiver, but the transmission source is any media such as a video disc or a laser disc, CATV or a new type. It can be applied to all transmission systems such as broadcasting formats. The receiver can be applied not only to CRT CTV but also to any color video signal display device such as flat panel display using liquid crystal and projection TV. Further, in the embodiment, the case of handling the Y, I and Q signals was described, but Y ₁ R-Y and B
The present invention can be applied to the case where all color video signals are handled because there is a one-to-one correspondence between these color video signals even when handling -Y signals and R ₁ G and B signals.

Further, in the embodiments, the case of the NTSC system is described, but the present invention can be applied to a color video signal transmission system that handles all composite video signals including internationally standardized systems such as PAL system and SECAM system. Is.

Further, in the present embodiment, the case where the luminance signal and the carrier color signal are transmitted through a plurality of different transmission paths has been described, but the luminance signal and the carrier color signal are frequency-multiplexed in different frequency bands, and further, It is also possible to perform time-axis compression multiplexing or transmission. For example, a chrominance signal has two color difference signals having a band of 5 MHz, is modulated by a subcarrier having a frequency twice the NTSC subcarrier frequency, is converted into a carrier color signal, and has this carrier color signal and a frequency band of 20 MHz. It is also possible to separately transmit, receive, and display the baseband luminance signal.

In addition, the color signals are two color difference signals with a band of 3MHz and NTSC.
It is also possible to modulate with a subcarrier having a frequency twice the subcarrier frequency, convert it into a carrier color signal, frequency-multiplex this carrier color signal and a luminance signal with a different frequency band, transmit, receive, and display. It is possible.

As described above, the transmission of the color video signal between the consumer VTR and the CTV is performed in the form of, for example, the composite video signal of the NTSC system, and the band of the luminance signal and the color signal is limited by the NTSC standard. However, the quality of the transmitted color video signal is deteriorated due to the interference due to the mutual interference, the waveform distortion due to the Y / C separation filter, and the additional noise of the circuit system.

According to the present invention, it is possible to transmit a high-quality luminance signal or chrominance signal in a wider band than the luminance signal or chrominance signal of NTSC standard by using VCR or CTV of NTSC standard. Especially VTR
When the color video signal output such as is not a recorded and reproduced NTSC color video signal such as a broadcast wave but is a luminance signal or a color signal that does not particularly pass through the NTSC system in a video camera, etc. The effect is very large. Furthermore, even when a component type color video signal is reproduced in a VTR, the color difference signal is converted to a carrier color signal and then transmitted, so that even if recorded as a component type color video signal, high-quality color Video signals can be transmitted.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of an embodiment of the present invention, and FIGS. 2 (a) to (i) are diagrams for explaining a relationship between a luminance signal and a color signal in a frequency band in the embodiment of the present invention and a conventional example. And FIG. 3 is a block diagram of a main part in the conventional example. 1 ... VTR color video signal processing circuit, 5 ... LPF1, 6 ...
… LPF2,7 …… LPF3,8 …… LPF4,9 …… LPF5,10 ……
LPF6, 11 ... Quadrature two-phase modulator, 12 ... Quadrature two-phase modulator,
13 …… Y / C mixing circuit, 14 …… RF modulator, 23 …… RF demodulator, 24 …… Y / C separation circuit, 25 and 29 …… Switch, 35
...... TV color video signal processing circuit.

Front page continued (72) Inventor Ryotomi Nagaoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Noriaki Gentsu, No. 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. Inventor Sasaki Nagasaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-84190 (JP, A)

Claims (5)

[Claims] 1. A wider band than the bands of two color difference signals forming a composite video signal which is a standard television signal, and a different number of scanning lines, a different number of effective scanning lines, a different aspect ratio, and a different field. Two color difference signals having all or any one of the characteristics with frequency are obtained by quadrature two-phase modulation with a color subcarrier that constitutes the composite video signal or a color subcarrier that can be created from frequency information of the composite video signal. And a luminance signal having the same number of effective scanning lines and an effective screen aspect ratio as those of the two color difference signals are separately transmitted via the output terminals of the component color image signals, and the composite image is transmitted. A color video signal characterized by transmitting a signal in which the carrier color signal and the luminance signal are frequency-multiplexed via an output terminal for transmitting a signal. Transmission method. 2. The color video signal transmission method according to claim 1, wherein the brightness signal has a wider band than a brightness signal forming the composite video signal. 3. A color video signal transmission method according to claim 1, wherein a composite video signal in which a transmitted luminance signal and carrier color signal are frequency-multiplexed is also transmitted at the same time. 4. The color video signal transmission method according to claim 1, wherein the luminance signal and the carrier color signal which are separately transmitted are transmitted through a plurality of different transmission paths. 5. A luminance signal and a carrier chrominance signal, which are separately transmitted, are switched to a luminance signal and a carrier chrominance signal whose frequency is separated from each other in the composite video signal receiving device. The color video signal transmission method according to claim 1.