KR200182490Y1 - The closed circuit tv system havign agc amplifier - Google Patents

Abstract

The present invention relates to a closed-circuit television system, and more particularly, to obtain a clearer video signal by improving a problem caused by noise generated in low light, and thus, to provide a clearer video signal at night or in low light. A closed circuit television system that can overcome vulnerabilities.

The closed circuit television system of the present invention processes a signal input through the lens 3a and the CCD 9 incorporated in the closed circuit camera body 1, and outputs the signal to the monitor 15. VSP including a DCS circuit portion for removing noise, an AGC circuit portion for amplifying to a constant level, a gamma circuit portion for adjusting the linearity of a video signal, a white clip circuit portion, a set-up circuit portion, a SAG correction circuit portion, and the like. (13) and a pulse generator (11) incorporating pulses and automatic IRIS functions required for the solid-state imaging unit and the image processing unit, wherein the output signal of the AGC circuit unit included in the VSP (13) is supplied. It further comprises a variable AGC amplifier 19 for amplifying and outputting a clear video signal to a monitor even in low light conditions.

Description

The closed circuit TV system havign AGC amplifier

The present invention relates to a closed-circuit television system, and more specifically, to obtain a clearer video signal by improving a problem caused by noise generated at low illuminance. A closed circuit television system that can overcome vulnerabilities.

Closed-circuit television (CCTV) is mainly used to monitor places that are difficult for humans to monitor directly. In other words, install a camera that can be remotely controlled in a place where people are resident and difficult to monitor, such as outside areas of buildings, underground parking lots, etc. . Referring to Figures 1 and 2 the operating state of a conventional closed-circuit television system is as follows.

1 is a side view of a camera body 1 conventionally used, and FIG. 2 is a schematic configuration diagram of a closed circuit television system including a camera body 1. The lens unit 3 is positioned at the front end of the camera body 1, and electronic circuits and devices necessary for capturing an image of a subject are embedded in the camera body 1. The light rays emitted from the subject 7 located in the direction of the lens unit 3 of the camera body 1 are inputted through the lens 3a of the lens unit 3, and then modulated by the CCD 9 again. Is output. The CCD 9 is a solid-state image pickup device that converts an optical signal into an electrical signal. The signal output from the CCD 9 is processed by the video signal processor (hereinafter referred to as 'VSP') 13 and then output through the monitor 15, and the operator can visually recognize it through the monitor 15. .

However, in the conventional closed circuit television system as described above, when operating in a low light condition, there is a problem that the image quality of the video output is degraded due to the increase in noise on the circuit, making it difficult to identify on the monitor.

This occurs during processing in the VSP. That is, conventionally, when gain is set on the VSP 13, the current signal level is always detected in a detection block included in the AGC circuit part embedded in the VSP 13, and is smaller than the reference level. The gain was increased, and when the gain was higher than the reference level, the gain was set to be lowered to be a constant level.

In particular, in the low light state, the state becomes lower than the reference level. In the AGC circuit part of the VSP 13, the gain is increased. At this time, noise is increased and it is difficult to see a clear image on the monitor 15. In addition, setting a low reference level at low illumination improves sensitivity, but results in deterioration of S / N and image quality.

The present invention has been made to solve the above problems, the object of the present invention is to improve the problem caused by noise generated in low light (低照度) can obtain a clearer video signal, at night or in low light The present invention provides a closed circuit television system capable of overcoming a weakness of a conventional closed circuit camera.

The closed-circuit television system of the present invention for achieving the above object processes a signal input through the lens (3a) and the CCD (9) built in the closed-circuit camera body 1 and outputs it to the monitor (15). A DCS circuit portion for removing noise in the input signal, an AGC circuit portion for amplifying to a constant level, a gamma circuit portion for adjusting the linearity of the video signal, a white clip circuit portion, a set-up circuit portion, A closed circuit television system comprising a VSP (13) including a SAG correction circuit portion and the like, and a pulse generator (11) with built-in pulses and automatic IRIS functions required for a solid-state image pickup portion and an image processing portion. It further comprises a variable AGC amplification unit 19 for amplifying the output signal of the included AGC circuit unit to output a clear image signal to the monitor even in low light conditions.

1 is a schematic view showing the appearance of a closed circuit camera conventionally used;

2 is a schematic block diagram of a closed circuit television system conventionally used;

3 is a schematic block diagram of a closed circuit television system according to the present invention;

4 is a flowchart showing an operating state of the present invention.

<Explanation of symbols for main parts of the drawings>

1: camera body 3: lens unit

3a: lens 5: signal output terminal

7: Subject 9: CCD

11: pulse generator 13: VSP

15: monitor 19: AGC amplifier

Hereinafter, a closed circuit television system of the present invention will be described in detail with reference to the accompanying drawings.

The present invention adds an amplifier to the outside of the VSP that processes the video in a closed circuit television, so that the noise does not increase even when the gain is amplified in a low light condition, so it can output excellent image quality, which can be useful at night or underground parking lot. .

First, the operation state of the VSP 13 and the pulse generator 11 of the conventional closed-circuit television system is as follows.

The noseVSP 13 is an IC for image signal processing, which is a CDS circuit which receives an output signal of the CCD 9 to remove noise, an automatic gain control (AGC) circuit which amplifies the input signal at a constant signal level, Gamma circuits, white clip circuits, set-up circuits, SAG correction circuits, sync. Mix circuit and output drive circuit are built in.

In particular, the AGC circuit consists of a gain control, a gain control max, a gain amplifier, a detection block, and has a range of about 4 to 32 dB. . As described above, the detection block serves to adjust the gain by comparing the signal level currently input with the reference level.

AGC (Auto Gain Control) is a circuit designed to increase the gain in order to clearly recognize the subject 7 when capturing dark areas, and the gain is limited to the value designed for the VSP. If the gain is maximized, a lot of noise is generated in low light and a clear screen cannot be obtained.

Reference numeral 11 denotes a pulse generator, which includes functions necessary for generating pulses required for the solid state imaging unit and the image processing unit including the solid state imaging element and the automatic IRIS function. Since the VSP is conventionally used, detailed circuits and explanations are omitted.

AGC amplifier 19 according to the present invention, with reference to Figure 3, is further added to the conventional VSP (13). The AGC amplifier 19 is not built into the VSP 13 but is installed as a separate external circuit. It is apparent that the AGC amplifier 19 can be configured using an amplifier for small signal amplification. And you can get about 4-52dB dain gain.

The control of the AGC amplifier 19 may be configured to automatically amplify when a low light condition is detected, or the operator may manually adjust the amplification degree by reporting an image output displayed on the monitor 15.

An operating state of the present invention having the above configuration will be described using the flowchart of FIG. 4.

When the operation of the closed circuit television system is started, the light input from the subject 7 is input through the lens portion 3 of the camera body 1. A lens 3a for condensing is provided inside the lens unit 3, and the focused light is input to the CCD 9 built in the camera main body 1, and thereafter, as an electric signal corresponding to the light. Is modulated.

The modulated signal is input to the VSP 13 as an electrical signal and processed. In the VSP 13, the intensity of the photographed place is determined by comparing the input electric signal with the signal. At this time, if the circumference of the subject 7 is dark, that is, in a low light condition, it is necessary to amplify the signal large in order to obtain a clear image output. This is determined by the signal control operation section.

Amplification of the signal is performed in the AGC amplifier 19. At this time, the degree of amplification can be variably controlled according to the sensed intensity of illumination. The amplified signal is output through the monitor 15 after being processed normally. Therefore, the operator can see a clearer video screen.

As a result of the comparison of the illuminance, if it is determined that the illuminance is not low, the AGC amplifier 19 outputs the AGC thrust signal normally without amplifying the AGC thrust signal. That is, it outputs as processed by the preset gain by the AGC circuit part of the VSP 13. This low light condition is very useful for use at places such as night or underground parking lot. That is, even if the lighting is operated at night, in order to save energy mostly, low illumination is maintained because of low illumination, and the underground parking lot also maintains low illumination, and thus has a complementary effect by the present invention.

Thus, according to the present invention, there is an advantage that the output of the video screen can be remarkably improved by amplifying the signal outside the AGC circuit part of the VSP 13. The amplification degree of the AGC amplifier 19 may be configured to be adjusted manually or automatically by the operator.

As described above, according to the present invention, it is possible to obtain a clearer video signal by improving the problem caused by noise generated in low light, and to overcome the weakness of the conventional closed circuit camera at night or low light. have.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that the present invention may be modified or changed within the spirit and scope of the present invention. something to do.

Claims (2)

The DCS circuit unit which removes noise in the input signal by processing the signal input through the lens 3a and the CCD 9 built in the closed circuit camera body 1 and outputting it to the monitor 15, A VSP 13 including a AGC circuit section for amplifying at a level, a gamma circuit section for adjusting the linearity of a video signal, a white clip circuit section, a set-up circuit section, a SAG correction circuit section, and the like, and a solid-state imaging section; In a closed circuit television system comprising a pulse generator 11 with built-in pulses and an automatic IRIS function required for an image processing unit, And a variable AGC amplifier (19) for amplifying the output signal of the AGC circuit part included in the VSP (13) to output a clear image signal to the monitor even in a low light condition. The method of claim 1, The AGC amplifier 19 is a closed circuit television system, characterized in that automatically adjusts the amplification degree in accordance with the low light conditions, or the operator adjusts manually by looking at the monitor screen.