JPH06141345A - Color video signal transmitter - Google Patents

Abstract

PURPOSE:To simultaneously transmit multiplexed audio base band signal and color video signal by using a pair cables. CONSTITUTION:A color video signal transmitter 1 is provided with a Y/C separation section 3 separating brightness signal and a chroma signal of an NTSC composite video signal, a brightness signal modulation section 4 frequency- modulating the brightness signal, and a chroma signal low frequency conversion section 5 converting the chroma signal into a low frequency chrominance subcarrier, the brightness signal and the chroma signal are converted into a frequency of a band different from that of a base band audio signal, multiplexed and sent through a pair cable 9a, 9b. On the other hand, the color video signal receiver 1 is provided with a signal separator section separating the modulated brightness signal subject to frequency multiplex processing and the chroma signal subject to low frequency conversion, a brightness signal demodulation display section demodulating the brightness signal, and a chroma signal frequency conversion section restoring the chroma signal subject to low frequency conversion into the NTSC chrominance subcarrier, receives the video signal subject to frequency multiplexing sent through the pair cable 9a, 9b and reproduces it into the NTSC composite video signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color video signal transmitting device, a color video signal receiving device and a color video signal transmitting device using them in a network system such as a color camera door phone system.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional audio and video transmission system such as a color camera door phone system.

In FIG. 4, 9a and 9b are signal transmission lines of twisted pair cables or parallel cables, and
A pair cable is composed of a and 9b. Reference numeral 22 denotes a video / audio transmission device such as a camera doorphone slave unit, which sends an audio signal input by the microphone 18, the speaker 19 and the microphone 18 to the pair cables 9a and 9b, and outputs audio on the pair cables 9a and 9b. An audio signal transmission unit 20 having a function of outputting a signal to the speaker 19 and including a hybrid circuit and a color camera 8 such as a CCD
Composed of. An audio transmission terminal 21 such as an intercom communication device is connected on the pair cables 9a and 9b, and the video / audio transmission device 22 and the audio transmission terminal 21 can talk in a baseband bidirectional manner. Further, the image picked up by the camera 8 is transmitted to the monitor 16 as an NTSC signal using the coaxial cable 23 as a medium and is displayed on the display of the monitor 16.

[0004]

In such a conventional color camera doorphone system, the coaxial cable 23 for video transmission is provided separately from the pair cables 9a and 9b for voice communication.
Therefore, there is a problem that the pair cables 9a and 9b for voice call and the coaxial cable 23 for video transmission must be wired.

In view of the above problems of the conventional color video signal transmission device, the present invention is a color video signal transmission device capable of wire saving by transmitting an audio signal and a color video signal with a pair of pair cables. , A receiving device and a transmitting device are provided.

[0006]

SUMMARY OF THE INVENTION The present invention is a color NT
The video signal input section for inputting the SC composite video signal, the Y / C separation section for separating the luminance signal and the chrominance signal of the composite video signal, and the luminance signal separated by the Y / C separation section for the first predetermined The luminance signal modulator that frequency-modulates in the frequency band and the color signal separated by the Y / C separator are
A color signal low-pass converting unit for low-pass converting to a second predetermined frequency band; a signal mixing unit for mixing an output signal of the luminance signal modulating unit and an output signal of the color signal low-pass converting unit; A signal transmission unit for converting an output signal to a balanced type and transmitting the converted signal to a signal transmission path represented by a twisted pair cable as a video transmission signal, wherein the first and second predetermined frequency bands are base frequencies. A color video signal transmitting device having a frequency band that does not overlap with a frequency band of a band audio signal and multiplexing and transmitting a video transmission signal and a baseband audio signal.

Further, according to the present invention, a video transmission signal in which a frequency-modulated luminance signal and a low-frequency-converted chrominance signal transmitted on a signal transmission path are combined is received in a balanced type and converted into an unbalanced type signal. A signal receiving unit for converting, a signal separating unit for separating a signal output from the signal receiving unit into a frequency-modulated luminance signal and a low-frequency converted color signal, and a frequency-modulated luminance signal separated by the signal separating unit Luminance signal demodulation unit that demodulates and converts to a luminance signal of an NTSC video signal, and the low frequency conversion color signal separated by the signal separation unit is converted to a color signal of an NTSC video signal in a frequency band centered at 3.58 MHz. It is equipped with a color signal frequency converter and a video signal output unit that synthesizes and amplifies the luminance component and color signal of the NTSC video signal and outputs as a color NTSC composite video signal. Receiving a video transmission signal transmitted in signal transmission line in a frequency band which does not overlap with the frequency band, a color video signal receiving apparatus which outputs display an image on the display device.

[0008]

According to the present invention, the luminance signal modulator and the color signal low frequency converter convert the color video signal into a frequency band which does not overlap with the baseband audio signal, and can transmit and receive the frequency band. A cable can transmit baseband audio signals and color video signals.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the color video signal transmitting apparatus of the present invention, and the configuration will be described together with the operation. In FIG. 1, reference numeral 1 is a color video signal transmitting apparatus which is an embodiment of the present invention. A color camera 8 such as a CCD is connected to the color video signal transmission device 1 and outputs an NTSC composite video signal thereto.
The NTSC composite video signal output by the camera 8 is
It is input to the video signal input unit 2 of the color video signal transmission device 1. NTSC input to the video signal input section 2
The composite video signal is separated into a baseband luminance component signal and a chrominance signal having a subcarrier frequency of 3.58 MHz by a Y / C separation unit 3 including a comb filter. The signal of the brightness component separated and extracted by the Y / C separation unit 3 is input to the brightness signal modulation unit 4, and is frequency-modulated by the brightness signal modulation unit 4 around 4 MHz, for example. On the other hand, the color component signals separated and extracted by the Y / C separation unit 3 are input to the color signal low frequency conversion unit 5, and the color signal low frequency conversion unit 5 converts the subcarrier frequency of 3.58 MHz to, for example, VTR.
It is converted to the low-frequency conversion color subcarrier frequency of 629 kHz, which is the same as the VHS method. The luminance signal frequency-modulated by the luminance signal modulator 4 and the chrominance signal converted to the low-frequency sub-carrier frequency by the color signal low-frequency converter 5 are input to the signal mixer 6 and then input to the signal mixer 6. Are frequency-multiplexed. The luminance signal and the chrominance signal, which are frequency-multiplexed by the signal mixing unit 6, are input to the signal transmitting unit 7, amplified by the signal transmitting unit 7, and matched with the characteristic impedance of the pair cables 9a and 9b which are transmission media. The output impedance and the balanced type are sent to the pair cables 9a and 9b. Here, the video signal transmitted by the color video signal transmitting device 1 to the pair cables 9a and 9b is the frequency band of the baseband audio signal, that is, 0.
It is composed of signals in a frequency band that does not overlap with 3 to 3.4 kHz.

In FIG. 2, reference numeral 10 is a color video signal receiving apparatus which is an embodiment of the present invention. The above-mentioned video signal, which has been multiplexed and modulated in a frequency band that does not overlap with the baseband audio signal transmitted on the paired cables 9a and 9b, which is a transmission medium, is received by the signal receiving unit 11 in the color video signal receiving apparatus 10. To be done. The signal receiving unit 11 has a function of converting a balanced input signal into an unbalanced signal, and is configured by a transformer or the like. The signal output from the signal receiving unit 11 is input to the signal separating unit 12, and the signal separating unit 12 outputs 4
The signal is separated into a frequency-modulated luminance component signal centered on MHz and a color component signal converted to a low-frequency subcarrier frequency of 629 kHz. The signal separation unit 12 is composed of a high pass filter, a low pass filter, and the like. The signal of the frequency-modulated luminance component separated and extracted by the signal separation unit 12 is input to the luminance signal demodulation unit 13 and demodulated by the luminance signal demodulation unit 13 into a baseband video signal of only the luminance signal. On the other hand, the low-frequency conversion color signal separated by the signal separation unit 12 is input to the color signal frequency conversion unit 14, and is converted into a color signal having a subcarrier frequency of 3.58 MHz of the NTSC composite video signal by the color signal frequency conversion unit 14. To be converted.
The luminance signal demodulated by the luminance signal demodulation unit 13 and the color signal converted to the original color subcarrier frequency of 3.58 MHz by the color signal frequency conversion unit 14 are input to the video signal output unit 15, and the video signal is output. The signal output section 15 mixes the luminance signal and the chrominance signal, and has an output impedance of 75 ohms and NTSC.
It is output as a composite video signal. This NTSC
The composite video signal is input to the external monitor 16 to display a color video.

FIG. 3 is a block diagram showing a color camera doorphone system, which is an embodiment of a color video signal transmission device using the color video signal transmission device 1 and the color video signal reception device 10 of the present invention.

In FIG. 3, as described in the conventional color video signal transmission apparatus of FIG. 4, 9a and 9b are signal transmission paths of twisted pair cables or parallel cables, and 9
A pair cable is composed of a and 9b. The video / audio transmission device 17 such as a camera doorphone slave unit includes a microphone 18,
The audio signal input through the speaker 19 and the microphone 18 is sent to the pair cables 9a and 9b,
The audio signal transmission unit 20 having a function of outputting the audio signal transmitted to the speakers a and 9b to the speaker 19 and including a hybrid circuit, the color camera 8 such as a CCD, and the color video signal transmission device of the present invention. It consists of 1. An audio transmission terminal 21 such as an intercom communication device is connected on the pair cables 9a and 9b, and the video / audio transmission device 17 and the audio transmission terminal 21 can talk in a baseband bidirectional manner. Also, the image captured by the camera 8 is input to the color video signal transmission device 1, and the color video signal transmission device 1 frequency-modulates the input NTSC composite video signal to obtain the frequency of the luminance signal and the low-frequency conversion color signal. The multiplexed signal is output to the pair cables 9a and 9b. The color video signal receiving apparatus 10 of the present invention is connected to the pair cables 9a and 9b, and the color video signal receiving apparatus 10 receives the video signals transmitted to the pair cables 9a and 9b and converts them into the original NTSC composite video signals. Play,
Output to the monitor 16.

The image picked up by the camera 8 as described above is transmitted through the pair cables 9a and 9b as a medium and is displayed on the display of the monitor 16.

Thus, the frequency band of the baseband audio signal transmitted on the pair cables 9a and 9b is about 0.
It is 3 to 3.4 kHz, and the transmission frequency band of the video signal that the color video signal transmission device 1 sends to the pair cables 9a and 9b is that the color signal is about 629 kHz ± 500 kHz and the luminance signal is about 4 MHz ± 500 kHz. Since the frequency bands of the audio signal and the video signal do not overlap, the audio signal and the video signal can be simultaneously transmitted by the pair of pair cables 9a and 9b.

[0016]

As is apparent from the above description,
According to the present invention, since a color video signal can be converted into a frequency band that does not overlap with a baseband audio signal and transmitted and received, it is possible to save wiring by transmitting an audio signal and a color video signal with a pair of pair cables. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color video signal transmission device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a color video signal receiving apparatus according to an embodiment of the present invention.

FIG. 3 is a block configuration diagram of a color camera doorphone system using the color video signal transmission device and the color video signal reception device of the above-described embodiment of the present invention.

FIG. 4 is a block diagram of a conventional color camera door phone system.

[Explanation of symbols]

 1 Color Video Signal Transmitting Device 2 Video Signal Input Unit 3 Y / C Separation Unit 4 Luminance Signal Modulating Unit 5 Color Signal Low Frequency Converter 6 Signal Mixing Unit 7 Signal Sending Unit 8 Camera 9a, 9b Pair Cable 10 Color Video Signal Receiving Device 11 signal receiving unit 12 signal separating unit 13 luminance signal demodulating unit 14 color signal low-frequency converting unit 15 video signal outputting unit 16 monitor 17 video / audio transmitting device 18 microphone 19 speaker 20 audio signal transmitting unit 21 audio transmitting terminal 23 coaxial cable

Claims (3)

[Claims] 1. A video signal input section for inputting a color NTSC composite video signal, and a Y / C separation section for separating a luminance signal and a color signal of the composite video signal.
A luminance signal modulator for frequency-modulating the luminance signal separated by the Y / C separator into a first predetermined frequency band, and a color signal separated by the Y / C separator for a second predetermined frequency band. A color signal low-frequency conversion unit that performs low-frequency conversion to a frequency band of: a signal mixing unit that mixes an output signal of the luminance signal modulation unit and an output signal of the color signal low-frequency conversion unit; A signal transmitting section for converting the signal into a balanced type signal and transmitting the converted signal to a signal transmission path typified by a twisted pair cable as a video transmission signal, wherein the first and second predetermined frequency bands are baseband. A color video signal transmitting apparatus having a frequency band that does not overlap with a frequency band of an audio signal, wherein the video transmission signal and the baseband audio signal are multiplexed and transmitted. 2. A signal reception for receiving a video transmission signal in which a frequency-modulated luminance signal and a low-frequency converted color signal transmitted on a signal transmission path are combined in a balanced type and converted into an unbalanced type signal. Unit, a signal separation unit that separates the signal output from the signal reception unit into a frequency-modulated luminance signal and a low-frequency-converted color signal, and demodulates the frequency-modulated luminance signal separated by the signal separation unit. And a luminance signal demodulation unit for converting into a luminance signal of an NTSC video signal, and a color for converting the low-pass conversion color signal separated by the signal separation unit into a color signal of an NTSC video signal in a frequency band centered at 3.58 MHz. The baseband audio signal is provided with a signal frequency conversion unit and a video signal output unit that synthesizes and amplifies the luminance component and color signal of the NTSC video signal and outputs as a color NTSC composite video signal. Color video signal receiving apparatus in the frequency band to receive the video transmission signal transmitted to the signal transmission path, and outputs display an image on a display device which does not overlap with the frequency band of. 3. The video signal transmitting device according to claim 1 and the video signal receiving device according to claim 2 are connected to a twisted pair cable in a home bus system, and a baseband audio signal and a video signal are multiplexed and transmitted. A color video signal transmission device characterized by.