JPS6379495A - Color video signal transmitting method - Google Patents

Abstract

PURPOSE:To transmit the video signal of a band wider than that of a standard system by two-phase modulating orthogonally two color difference signals to have a carrier chrominance signal and separately transmitting a luminance signal and the carrier chrominance signal from a VTR to a CTV. CONSTITUTION:The luminance signal Y and the color difference signals I, Q outputted from the color video signal processing circuit 1 of the VTR are respectively fed to LPFs 1, 3, 5 band controlled by a standard NTSC and to LPFs 2, 4, 6 of the band wider than it. The I, Q signals of the outputs of the respective LPFs are made to the carrier chrominance signal by orthogonal two-phase modulators 11, 12 and fed to a transmission path. The luminance signal Y1 is fed to the transmission path via a Y/C mixing circuit 13 and the luminance signal Y2 is transmitted to the transmission path independently of the chrominance signal. At a TV side, switches 25, 29 are provided, either one of the luminance signal and the color difference signal of the standard system and the luminance signal and the color difference signal of the band wider than that of the standard system is selected by switching them and fed to a TV color signal processing circuit 35.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of transmitting color video signals from a color video signal transmitting device such as a video tape recorder or a video disc to a color video signal receiving device such as a color television. be.

2. Prior Art In the field of conventional consumer video tape recorders (abbreviated as VTR), VTR and color television (CT)
A composite video signal (combo-dift video signal) in which a luminance signal and a carrier color signal are frequency-multiplexed is used to transmit color video signals between the baseband (baseband) or broadcast wave band (RF band). It is being For example, as described in Broadcasting Technology Magazine, August 1983 issue, pages 59-71, when transmitting color video signals between a VTR and a so-called AV system TV, NTSCi is used from the video output terminal of the VTR. A baseband transmission format is used in which a baseband signal of a combined video signal is transmitted and received by the video input terminal of the AV system TV. This baseband transmission of composite video signals between a VTR and CTV can be said to be an excellent transmission method that causes less deterioration of the composite video signal than transmission in the broadcast wave band because it does not pass through an RF converter or filter. .

However, in standards such as the VH3 standard and β standard in NTSC consumer VTRs, 8tm VTRs, and even VHD video discs, the luminance signal and color signal are recorded separately (i.e.,
The luminance signal and color signal are treated as component signals and recorded separately. ) also outputs a composite video signal in which the luminance signal and the carrier color signal are frequency multiplexed as the output signal from the VTR, and transmits it to the CTV, where it is frequency-multiplexed again into the luminance signal and the carrier color signal using a comb filter, etc. The extra operations of frequency multiplexing and frequency separation are performed. In other words, in frequency multiplexing and frequency separation of luminance signals and carrier chrominance signals, the amplitude and phase information of the transmitted signal is lost due to imperfections in the Lylter and amplifier, and circuit noise is added, deteriorating the quality of the transmitted signal. have points.

Hereinafter, the conventional VTR and CT described above with reference to the drawings will be explained.
An example of a method for transmitting a color video signal as a composite video signal between Vs will be described. Figure 3 shows conventional VTR and CTV
FIG. 2 is a block diagram of main parts of an example of a color video signal transmission system between the two.

In FIG. 3, a luminance signal and a color signal to be recorded or reproduced in a VTR are outputted to output terminals 2.3 and 4 of a VTR color video signal processing circuit 1, respectively.

In Fig. 3, the luminance signal (Y signal, Y signal in Fig. 2 (al)) is output from output terminal 2, and the chrominance signal (r signal, Q signal, I, Q signal in Fig. 2 Cbl) is output from output terminals 3 and 4. ) are output respectively.These Y, I and Q
The signals reach low-pass filter 1 (abbreviated as LPFI), LPF3 and LPF5, respectively, and the respective outputs are Y, il and Ql in Fig. 2 tc+, +d).
Bandwidth is limited as shown below. Y in NTSC standard system
, 1 and Q signals are respectively 4.
2 Mtlz, 1.5 MHz and 0.5 Mtlz. These are the output signals of LPF3 and LPF5! , and the Q1 signal reaches the quadrature two-phase modulator 11 with 3.5795
The subcarrier of 45 MHz is used for carrier suppression quadrature two-phase amplitude modulation and becomes a signal at the ridge in the Y/C mixing circuit 13.
Figure 2 shows the output signal of the LPFI (Y in C1).
1 signal and becomes the composite video signal shown in Figure 2 (hl).If 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
It is output from the output terminal 15 of the CTV, inputted from the input terminal 19 of the CTV, and reaches the Y/C separation circuit 24 in the CTV. Also V
When the composite video signal is transmitted from the TR to the CTV in the broadcast wave band, the output of the '//C mixing circuit is transmitted to the RF modulator 1.
4 and modulated into the broadcast wave band from the output terminal 16 of the VTR.
The signal reaches the input terminal 20 of the TV, is demodulated again into a baseband composite video signal in the RF demodulator 23, and reaches the Y/C separation circuit in the CTV. In the Y/C separation circuit, Figure 2 (hl
The composite video signal shown in
cl Y,) and the carrier color signal (e.g. tF6 in Fig. 2)
The signals are frequency-separated into K) and input to input terminals 33 and 34 of the TV color video signal processing circuit 35, respectively.

Problems to be Solved by the Invention As mentioned above, in the conventional transmission of color video signals between a VTR and a CTV, the luminance signal and the carrier color signal are transmitted in the form of a composite video signal that is frequency-multiplexed. During frequency multiplexing of the luminance signal and carrier chrominance signal and frequency separation on the TV side, imperfections in filters and amplifiers can damage the amplitude and phase information of the transmitted signal, causing waveform distortion and adding circuit noise. Therefore, there is a major problem in that the quality of the transmitted signal deteriorates.

In addition, for example, in the NTSC system, the luminance signal and the carrier chrominance signal are frequency multiplexed in a frequency interleaved relationship, and cross interference due to mutual interference between the luminance signal and the chrominance signal occurs.
There is a problem in that color and cross luminance become noise and have a large negative impact on image quality.

Furthermore, in the NTSC system, the luminance signal band is 4.2
Since the bands of MIIz and chrominance signals are determined to be 1.5MHz and 0.5MHz for the summer signal and Q signal, respectively, it is natural that the luminance and chrominance signals have wider bands than those determined by the NTSC standard. cannot be transmitted.

When an NTSC signal is used for broadcast radio waves, its composition as a composite video signal is effective, but when used in situations other than broadcast radio waves, it is often subject to restrictions as a composite video signal. This is a drawback.

In view of the above problems, the present invention provides a VTR that handles NTSC signals.
By making significant additional changes to the output circuit system of the CTV and the input circuit system of the CTV, it would be possible to easily transmit the luminance signal and carrier color signal between the VTR and the TV with a higher bandwidth and higher quality than when handling NTSC standard signals. This provides a transmission method that allows

In addition, EDTV (Exten TV) compatible with NTSC system
ded Definition TV) and HDTV (
This provides a transmission method that can be very effective for transmission near the baseband such as the former ghDefinjtion Tv).

Means for Solving the Problems In order to solve the above problems, in the present invention, for example, a luminance signal and a carrier color signal in a band wider than the band limited by the NTSC standard are separated and outputted from a VTR, Transmit to CTV. In a CTV, these wideband luminance signals and carrier color signals are switched to the luminance signal output and carrier color signal output of a Y/C separation circuit, and converted into wideband, high-quality R, G, and B signals in a color video signal processing circuit. It is converted and transmitted to the display unit.

Operation In the present invention, by the method described above, the conventional NTSC
Although VTRs and CTVs receive composite video signals,
This enables component transmission of high-quality color video signals with a wider band than that determined by the NTSC standard, without mutual interference such as cross color or cross luminance, and with less additional noise in the circuit system. It is particularly effective for component transmission of high quality video signals such as EDTVJpHDTV.

Embodiment Hereinafter, an embodiment of the color video signal transmission method of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of main parts in one embodiment of the present invention. In Figure 1, V
Output terminal 2 of VTR color video signal processing circuit 1 in TR
, 3 and 4 respectively output a luminance signal and a color signal to be recorded or reproduced in the VTR. In Fig. 1, the luminance signal (Y in Fig. 2 fal) is output from the output terminal 2.
signal) output terminals 3 and 4 output the color signal (Fig. 2(b)
summer signal and Q signal) are output respectively. Output terminal 2
The output Y signal is branched into two systems and one is NTS
Input to LPF 1 which performs C method band limitation, and the other one is more than LPFI! Input to LPF2 with wide overband. Further, the (2) signal outputted from the output terminal 3 is branched into two systems, one of which is input to an LPF 3 that limits the band of the NTSC system, and the other is input to an LPF 4 having a wider passband than the LPF 3. The Q signal output from output terminal 4 is branched into two systems, one of which is input to an LPF that limits the band of the NTSC system, and the other is input to an LPF that has a wider passband than LPF5.
Enter. As a result, LPF 1°LPF3. LPF5
The outputs are the Y1 signal in FIG. 2 tel, the 11 signal and the Q1 signal in FIG. 2 fdl, respectively. Also LPF2. The outputs of LPF4 and LPF6 are the second
Y2 signal in figure te+, ■2 in figure 2 ffl
signal and Q2 signal. ■1 which is the output of LPF3
The signal and the Q1 signal, which is the output of the LPF 5, are subjected to carrier suppression quadrature two-phase amplitude modulation using a subcarrier in the NTSC system in a quadrature two-phase modulator 11, and then converted into a signal in the Y/C mixing circuit 13 (see FIG. 2). At this point, it is frequency multiplexed with the Y signal output from LPF 1, resulting in a composite video signal shown in FIG. 2 (hl).

When the composite video signal is transmitted from the VTR to the CTV in the baseband, the output of the Y/C mixing circuit is output from the output terminal 15 of the VTR and input from the input terminal 19 of the CTV.
It reaches the Y/C separation circuit 24 in the TV. Also, from the VTR
When the composite video signal is transmitted to the TV in the broadcast wave band, the output of the Y/C mixing circuit is changed to the broadcast wave band by the RF modulator 14 and is sent from the output terminal 16 of the VTR to the input terminal 20 of the CTV. It is then demodulated into a baseband composite video signal again in the RF demodulator 23 and sent to the Y/C separation circuit 24 in the CTV.
leading to. In the Y/C separation circuit, the composite video signal shown in FIG. 2 (hl) is frequency-separated into a luminance signal shown by the K1 signal in FIG. Input terminal 26 of switch 25, respectively
and is input to the input terminal 30 of the switch 29. By the way, the I2 signal which is the output signal of LPF4 and the Q2 signal which is the output signal of LPF6 are N
In the TSC system, the subcarrier is quadrature two-phase amplitude modulated and becomes the 21st K (11) signal, which is output from the output terminal 18 of the VTR and reaches the input terminal 22 of the CTV.
It reaches the input terminal 31 of the switch 29 inside. Also LPF2
The K2 signal which is the output signal of is output from the output terminal 17 of the VTR, reaches the input terminal 21 of the CTV, and reaches the input terminal 27 of the switch 25 in the CTV. When outputting the K1 signal to the output terminal 28 of the switch 25, the input terminal 26 and the output terminal 28 are brought into conduction, and when the K2 signal is outputted, the input terminal 27 and the output terminal 28 are brought into conduction. Also switch 2
When outputting a signal to output terminal 32 of 9, input terminal 3
0 and the output terminal 32, and when outputting the K1 signal, the input terminal 31 and the output terminal 32 are electrically connected. Two output terminals 2 and 32 of switch 25 and switch 29 are connected to input terminals 33 and 34 of a TV color video signal processing circuit 35, respectively. That is, the switches 25 and 29 can switch between the luminance signal and the carrier color signal input to the TV color video signal processing circuit. That is, it is possible to input a luminance signal and a carrier color signal having a wider band than the NTSC standard signal to the TV color video processing circuit. Now, the input terminal 3 of the TV color video processing circuit 35
Since the wideband carrier color signal input from 4 is also modulated with the NTSC subcarrier, it is easy to demodulate it into wideband I2 and Q2 signals or RY and BY signals. The passband of the filter of the carrier color signal demodulation circuit is set to 11 signals, Q1 signal, I2 signal and Q2.
By controlling with a signal or the like, a color difference signal with a good signal-to-noise ratio can be obtained, and as a result, a wide band and high quality RGB signal can be obtained.

As detailed above, the color difference between NTSC VTR and CTV! In transmitting IL image signals, it is possible to easily transmit higher quality luminance signals and color signals in a wider band than the NTSC standard.

In the embodiment, we have described a case in which a VTR is used as the transmission source of the wideband luminance signal and color signal, and a CTV is used as the receiver, but the transmission source can be any type of pancake media such as video discs or laser discs, or CAT.
It can be applied to all kinds of transmission systems such as V and new broadcasting layers.

Further, as a receiver, it can be applied not only to a CRT (CTV), but also to any color video signal display device such as a flat display using a liquid crystal or the like, or a projection TV. Furthermore, in the embodiment, the case where Y, ■, and Q signals are handled has been described, but when handling Y, RY, and B-Y signals, R, G, and B signals, etc., there is a difference between these color video signals. Since there is a one-to-one correspondence, the present invention can be applied to cases where any color video signal is handled.

Furthermore, although the embodiments have been described using the NTSC system, the present invention can also be applied to color video signal transmission systems that handle all composite video signals, including internationally standardized systems such as the PAL system and SECAM system. It is possible.

Furthermore, in this embodiment, a case has been described in which the luminance signal and the carrier color signal are transmitted through a plurality of different transmission paths, but the luminance signal and the 11 color signals may be frequency-multiplexed into different frequency bands, or Furthermore, it is also possible to perform time axis compression multiplexing and transmit. For example, the color signal is modulated with a subcarrier with a frequency twice the NTSC subcarrier frequency, converted to a carrier color signal, and frequency-multiplexed with this carrier color No. 13 and a baseband luminance signal in a different frequency band, and then transmitted. etc. are also possible.

Effects of the Invention Conventionally, color video signals are transmitted between a consumer VTR and a CTV in the form of a composite video signal of the NTSC system, for example, as described above, and the bands of luminance signals and color signals are limited by the NTSC standard. In addition, the quality of the transmitted color video signal is degraded by interference due to mutual interference, waveform distortion due to Y/C separation filters, and additional noise from the circuit system.

According to the present invention, there is a great effect that it is possible to transmit brightness signals and color signals with higher quality in a wider band than the brightness signals and color signals of the NTSC standard using an NTSC standard VTR or CTV. In particular, if the color video signal output from a VTR or other device is not one recorded or played back from an NTSC color video signal such as a broadcast wave, but is a luminance signal or color signal that does not pass through the NTSC system from a video camera, etc., the luminance signal Since the color signal and color signal are always treated as separate component signals, the image quality improvement effect of the present invention is very large. In particular, when the present invention is applied to the transmission of high-definition video signals such as HDTV and HDTV, it is possible to transmit component signals while maintaining compatibility with conventional receivers. HD T
This is a very effective means for transmitting the V signal once it has been demodulated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts in an embodiment of the present invention, and FIGS. 2(a) to (11) explain the relationship in frequency bands between luminance signals and chrominance signals in an embodiment of the present invention and a conventional example. The explanatory diagram and FIG. 3 are block diagrams of main parts in the conventional example. 1... VTR color video signal processing circuit, 5...
...LPFI, 6...LPF2.7...
...LPF3.8...LPF4.9...
...LPF5.10...LPF6.11...
... Quadrature two-phase modulator, 12... Quadrature two-phase modulator, 13... Y/C mixed circuit, 14...
...RF modulator, 23...RF demodulator, 24.
...Y/C separation circuit, 25 and 29...
- Switch, 35...TV color video signal processing circuit. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 2

Claims (4)

[Claims] (1) Convert two color difference signals to NTSC, PAL, or S
A color subcarrier determined by a composite video signal standard such as the ECAM system is quadrature-two-phase modulated to produce a carrier color signal, and the luminance signal and the carrier color signal are separated and sent to a color video signal transmitter and a color video signal. A color video signal transmission method characterized by transmitting between receiving devices. (2) The color video signal transmission method according to claim (1), wherein the luminance signal and the carrier color signal, which are transmitted separately, are transmitted through a plurality of different transmission paths. (3) The luminance signal and carrier color signal that are separated and transmitted are N
Claims characterized in that the luminance signal and carrier chrominance signal each or at least one of which has a wider band than the luminance signal and chrominance signal defined by a composite video signal standard such as TSC, PAL, or SECAM system. The color video signal transmission method according to item (1). (4) The luminance signal and carrier chrominance signal that are separated and transmitted can be switched to frequency-separated luminance signals and carrier chrominance signals from a composite video signal such as NTSC, PAL or SECAM system in the color video signal receiving device. A color video signal transmission method according to claim (1).