JP2985259B2 - Cable TV signal transmission system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a signal transmission system applied to a cable television.

[Summary of the Invention] The present invention is to independently transmit the R signal, the G signal, and the B signal constituting a wide picture size video signal using different channels, and to convert the wide picture size video signal. By transmitting independently the composite video signal of the normal image size obtained by using a channel different from the above-mentioned channel, it is possible to receive a signal with high color resolution at low cost and receive broadcast for large screen at low cost It is.

[Related Art] In recent years, television broadcasts have been viewed and viewed on a large-screen wide screen (for example, 2.4 m wide). However, in a normal broadcast format, the color resolution is as low as about 50 lines. . For this reason, a technique has been proposed for increasing the color resolution by independently transmitting the luminance signal and the chroma signal using different channel stations in satellite broadcasting.

[Problems to be Solved by the Invention] However, if a plurality of channels are used in satellite broadcasting as described above, two expensive tuners for satellite broadcasting must be prepared on the receiving side as well as on the transmitting side. However, there is a disadvantage that the transmission method becomes very expensive.

Therefore, an object of the present invention is to provide a transmission system that can receive a broadcast for a large screen at low cost.

[Means for Solving the Problems] A signal transmission system for a cable television according to the present invention for achieving the above object uses an R signal, a G signal, and a B signal which constitute a video signal of a wide picture size using different channels. The composite video signal of the normal picture size obtained by converting the video signal of the wide picture size is transmitted independently using a channel different from the above-mentioned channel.

[Operation] For a video signal of a wide image size, three tuners need to be installed on the receiving side because three channels are used. However, since the signal is transmitted by a cable, the video signal is transmitted at a low frequency and is not affected by disturbance. It is sufficient to prepare three inexpensive tuners.

Even when only one tuner is provided, the same broadcast as the wide image size can be received in the normal image size.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of a signal transmission system showing one embodiment of the present invention. In FIG. 1, a transmitting device A on the broadcasting side and receiving devices B ₁ and B ₂ on the user side are connected via a cable c to form a cable television system. Cable television has one to n channels. Transmitter A has n modulators M ₁ ~M _n corresponding to the n-channel from one channel, each modulator M ₁ ~M _n modulation television signals at different frequencies f ₁ ~f _n respectively I do. On the other hand, the R signal, G signal, and B signal output from the camera 1 have a wide image size (aspect ratio: 9:16)
Of a television signal, these color signals are respectively input to three modulators M ₁ ~M _3. These color signals are transmitted as television signals of 1 to 3 channels, respectively. The R signal, G signal and B signal of the camera 1 are also guided to an image size converter 2, where they are converted into a composite signal having a normal image size (aspect ratio is 3: 4). The result of the conversion, the vertical without the television signal on the screen by inserting an image signal of the black, the composite signal is directed to the modulator M _4, are transmitted as a television signal of four channels. Although not well shown in the other modulator M ₅ ~M _n led the television signal, the output of this all of the modulator M ₁ ~M _n is transmitted is superimposed at the adder 3.

One receiving device B ₁ represents a three tuners C ₁ -C _3, television signals from the cable c to the tuners C ₁ -C ₃ is input. Tuner C ₁ to frequency f _1, the tuner C ₂ to frequency f _2, the tuner C ₃ is tuned respectively to the frequency f _3. The output of each tuner C ₁ -C ₃ is guided to the projector view the picture, for example, in large-screen widescreen (width 2.4 m) (not shown).

The other receiving devices B ₂ has only one tuner C _4, is tuned to the frequency f ₄ is a television signal from the cable c as in the input to the tuner C _4. The output of the tuner C ₄ are guided for example to the small screen of the monitor (not shown).

In the above configuration, when broadcasting from channels 1 to 4 starts, the R signal of the television signal of the camera 1 is converted into a 1-channel television signal.
The G signal is a 2-channel television signal, and the B signal is a 3-channel television signal.
And the normal size composite signal is also transmitted as a 4-channel television signal. One receiving device B ₁ receives broadcasts from channel 1 to channel 3, tuner C ₁ receives an R signal,
The tuner C ₂ is G signal, the tuner C ₃ may receive respectively the B signals, these signals projector image is sent to the (not shown) to the wide screen is displayed. This video has a high color resolution because each color signal is transmitted on an independent channel. Then, it is necessary to three tuners C ₁ -C ₃ is a very inexpensive because it is intended to receive a signal transmitted by the cable c. Other receiving devices B ₂ receives the broadcast of 4 channels, the television signal of the composite is displayed on the monitor (not shown). Thus, users with three tuners C ₁ -C ₃ can receive the broadcast suitable for a large screen, and a user who has only a single tuner C ₄ is not able to receive broadcast for large-screen You can receive the same broadcast.

It should be noted that, for example, Y
When handling signals (4.5 MHz), RY signals (1.5 MHz), and BY signals (1.5 MHz), it is preferable to convert the signals to RGB signals before transmitting.

[Effects of the Invention] As described above, according to the present invention, the R signal, the G signal, and the B signal constituting a video signal of a wide image size are transmitted independently using different channels, and Since the composite video signal of the normal image size obtained by converting the video signal of the size is independently transmitted using a channel different from the above-described channel, if three inexpensive tuners for cable TV are used, a high color resolution can be obtained. It is possible to receive a signal and to receive a broadcast for a large screen at low cost.

Further, even if the user has only one tuner, it is not possible to receive a broadcast for a large screen, but it is possible to receive the same broadcast.

In addition, when transmission is performed wirelessly using a plurality of channels as in satellite broadcasting, a disturbance such as a time lag occurs due to disturbance, but the present invention has an advantage that such a trouble does not occur because the signal is transmitted through a cable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram of a signal transmission system showing one embodiment of the present invention. c ... Cable.

Claims (1)

(57) [Claims] An R signal, a G signal and a B signal constituting a wide picture size video signal are transmitted independently using different channels, and the wide picture size video signal is converted. A signal transmission system for a cable television, wherein a composite video signal of a normal image size is independently transmitted using a channel different from the above-mentioned channel.