JPH01243794A - Color television calling device - Google Patents

Abstract

PURPOSE:To automatically cut the uncomfortable color of a subject and to switch an image to a monochromatic image under a environment where the illumination intensity of the subject goes to be low, by providing a color killer means in the color television of a slave device at the door. CONSTITUTION:A switching circuit 7 is provided as the color killer means to erase the color burst signal of 3.58MHz from a video signal. When the bright subject is image-picked up, since the signal to be over a level determined by a reference voltage generator 10, is outputted from an amplifier 3, a comparator 9 is not operated. When the dark subject is image-picked up, since the signal to be under the level determined by the generator 10, is outputted from the amplifier 3, the comparator 9 is operated and the switching circuit is opened. Thus, the color burst signal of 3.58MHz is interrupted and the composite video signal of no color burst signal is sent from a terminal 1a. Thus, a color, which is unnatural and dull, at the time of the dark subject is erased and a picture easy to see can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color television communication device, and in particular, a device for receiving a composite video signal captured by a color camera built into a doorway handset on a color monitor built into a living room unit. The present invention relates to a color television communication device.

[Prior Art] As shown in FIG. 2, a conventional color television communication device receives a composite video signal captured by a color camera 20 built into an entrance handset on a color monitor 21 built into a living room unit. The color camera 20 includes a lens 2a, a color filter 2b, and a CCD.
An image of a subject is captured by an imaging unit 2 comprised of 2c. Imaging unit 2
are timing pulse generator 6, camera synchronization signal generator 5
．． It is controlled by driver 4. With this control, the signal captured by the imaging unit 2 is sent to the amplifier 3.3MHz low-pass filter 11.
, the yellowness signal detector HDYe, the green chromaticity signal detector HDG, and the cyan chromaticity signal detector HDCy, and are sent to the luminance signal processor PY, red processor PR, green processor PG, and blue processor PB. The signals processed by the red processor PR, green processor PG, and blue processor PB pass through the matrix 12 to become R-Y color difference signals and B-Y color difference signals, and then go through low-pass filters 13 and 14 to the encoder 15 and the luminance signal processor. It is combined with the luminance signal formed by PY to form a composite video signal. The composite video signal is composed of a luminance signal, a synchronization signal, and a 3.58 MHz color burst signal, and the color monitor 21 identifies whether it is a composite video signal based on the presence or absence of the color burst signal organized on the back porch of the horizontal retrace period. do.

The color monitor 21 has the same configuration as a normal color television, and detailed description thereof will be omitted. In the figure, 22 is a first video amplifier, 23 is a delay circuit, 24 is a second video amplifier, 25
is a band amplifier, 26 is a color demodulator, 27 is a matrix circuit, 28 is a color cancellation circuit, 29 is a burst gate amplifier,
30 is a gate pulse delay circuit, 31 is a synchronous separation circuit, 3
2 is a color synchronous phase detector, 33 is a vertical deflection circuit, 34 is a horizontal deflection circuit, 35 is a high voltage rectifier circuit, 36 is a convergence circuit, and 37 is a picture tube.

[Problems to be Solved by the Invention] Conventional color TV communication devices must process signals captured by the imaging unit 2 in a very bright state during the day, and must image a subject in a dimly lit state at night. Since this change between the bright state and the dark state is extremely large, the signal-to-noise ratio (hereinafter referred to as S/N ratio) of the composite video signal is worse than that of the black-and-white video signal when the subject illuminance is low. A composite video signal with a poor S/N ratio has poor color reproducibility, and there are problems that need to be solved, such as poor color reproduction, especially in shadow areas. Furthermore, when trying to capture an image by illuminating a subject with infrared illumination in an environment such as nighttime where subject illumination is not available, the color camera 2o has problems that must be resolved, such as compiling a composite video signal with unnatural colors. There is.

[Purpose of the Invention] The present invention has been made in view of the above-mentioned points, and provides a color television communication device that automatically cuts out the harsh colors of the subject and switches to black-and-white video in an environment where the illuminance of the subject is low. The purpose is to provide.

[Means for Solving the Problems] A color television communication device according to the present invention includes a color camera provided in an entrance handset, and a color monitor that receives a composite video signal generated by the color camera.

a video signal level detection means for detecting the level of a video signal imaged by the color camera; and a 3.58 MHz color signal from the composite video signal when the video signal level obtained by the video signal level detection means is below a predetermined level. and color killer means for erasing burst signals.

[Embodiment of the Invention] Hereinafter, an embodiment of a color television communication device according to the present invention will be described in detail with reference to FIG.

Components that are the same in FIG. 1 and FIG. 2 are designated by the same reference numerals, so their explanation will be omitted.

In FIG. 1, numeral 1 is a color camera built into the entrance cordless handset. The color camera 1 has a lens 2a and a color filter 2b.
, has an imaging section 2 equipped with a CCD 2c, and the imaging section 2 that takes an image of a subject (not shown) is controlled by a timing pulse generator 6, a camera synchronization signal generator 5, and a driver 4, which is controlled by an amplifier 3. Outputs the captured video signal.

A rectifier 8, a comparator 9°, and a reference voltage generator 10 are provided as video signal level detection means for detecting the level of this video signal. Also, from the composite video signal, 3.58
A switching circuit 7 is provided as color killer means for erasing the MHz color burst signal. During normal operation, the switching circuit 7 transmits the 3.58MHz color burst signal generated by the camera synchronization signal generator 5 to the yellowness signal detector HDYe and the green chromaticity detector I-IDG.
, is sent to the cyan chromaticity signal detector HDCy. When opened, the 3.58 MHz color burst signal is cut off. The switching circuit 7 is opened by the output of the comparator 9 when the level of the video signal output from the amplifier 3 falls below the level determined by the reference voltage generator 10.

When the switching circuit 7 is opened, the outputs of the red processor PR, green processor PG, and blue processor PB are not organized into the R-Y color difference signal and the B-Y color difference signal in the matrix 12, so that only the luminance signal processor PY operates.

[Operation of the invention] When imaging a bright object, the amplifier 3 outputs a video signal higher than the level determined by the reference voltage generator 10, so the comparator 9 does not operate.
The color burst signal is transmitted from the camera synchronization signal generator 5 to the yellowness signal detector HDYe via the switching circuit 7.
, a green chromaticity signal detector HDG, and a cyan chromaticity signal detector HDCy. Therefore, a composite video signal is sent from the terminal 1a of the color camera 1 to the terminal 21a of the color monitor 21 of the room unit shown in FIG. The color monitor 21 that has received the composite video signal sends the color burst signal separated from the first video amplifier 22 to the color synchronization phase detector 32 via the burst gate amplifier 29. Picture tube 37
You can monitor color images.

When imaging a dark object, a video signal lower than the level determined by the reference voltage generator 10 is output from the amplifier 3, so the comparator 9 operates and the switching circuit 7 is opened. Therefore, the 3.58 MHz color burst signal is cut off, and a composite video signal without the color burst signal is sent out from the terminal 1a. Since there is no color burst signal in the color monitor 21 that received this composite video signal, 1
The color erasing circuit 28 operates, and a black and white image can be monitored on the picture tube 37. This eliminates unnatural dull colors when photographing a dark subject, resulting in an image that is easy to view.

[Effects of the Invention] The color TV communication device according to the present invention has a structure in which the color camera installed in the entrance handset is equipped with a color killer means, so that when the illuminance of the subject becomes low such as at night, the color in the composite video signal is automatically detected. The feature is that it cuts the color signal component. Therefore, when the illuminance of the subject is low, it is possible to obtain clear black and white images without unnatural dull colors. A similar effect can also be obtained by using infrared illumination at night.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a color television conversation device according to the present invention, and FIG. 2 is a block diagram of a conventional color television conversation device. 1...Color camera 7...Switching circuit (color killer means) 8
... Rectifier (video signal level detection means) 9 ...
... Comparator (Video signal level detection means) 10 ... Reference voltage generator (Video signal level detection means) Agent Patent attorney -Yo Moritani

Claims (1)

[Claims] A video signal level for detecting a level of a video signal imaged by the color camera in a color television communication device equipped with a color camera provided in an entrance handset and a color monitor that receives a composite video signal generated by the color camera. It is characterized by comprising a detection means and a color killer means for erasing the 3.58 MHz color burst signal from the composite video signal when the video signal level obtained by the video signal level detection means is below a predetermined level. Color TV communication device.