KR20030036484A - True Day Night Camera - Google Patents

Abstract

PURPOSE: A monitoring camera with multi-illuminance is provided to monitor an object with high resolution and sensitivity even in a low-illuminance state. CONSTITUTION: A monitoring camera is constructed in such a manner that an image that has passed through a lens and a filter is converted into an electric signal by a CCD, a correlated double sample(14) extracts a video signal component from the signal output from the CCD to control gain of the video signal, and a digital signal processor processes digital video data to output a video signal. The filter is composed of an optical low pass filter and a glass filter that are arranged in parallel with each other. In a low illuminance state having no light, a filter changer removes color burst and the optical low pass filter is replaced by the glass filter so that the camera operates as a monochrome camera. In a specific illuminance state having lights, the filter changer restores the color burst and the glass filter is replaced by the optical low pass filter so that the camera operates as a color camera.

Description

True Day Night Camera {True Day Night Camera}

The present invention relates to a multi-illuminance monitoring camera, and more particularly, to a camera capable of monitoring a subject in a state of good resolution or sensitivity even in a low illuminance state without light in a constant illuminance environment.

CCD cameras are widely used as the most obvious means of surveillance in security surveillance, and classified into B / W CAMERA and COLOR CAMERA depending on the color reproducibility of the captured subject screen. The demand for color cameras is increasing rapidly according to the development of camera development technology and the colorization of market demand. The color camera can provide the monitor with the color information of the subject, so that the subject (water) can be used during the day compared to the monochrome camera. While the recognition rate is high, the monitoring efficiency is good, but at night, even in a little dark environment, the sensitivity is significantly worse than that of the black and white camera, so the monitoring ability is lost.

The sensitivity characteristics of a camera, which shows its surveillance capability in dark environments (low light conditions), are represented by the minimum illuminance value, which reduces the amount of light to the subject being captured by the camera and reduces the camera's video signal output level (LEVEL: IRE). The unit is expressed in units and 1IRE is 7.14mV), which is a measure of the brightness of the light irradiated on the subject with a light meter (LUXMETER). It's a camera that gives you the ability to monitor even darker places, and you get a brighter screen when you're capturing an equally dark subject.

The sensitivity characteristics of color CD cameras are generally around 1.5 lux, which is about 1/10 worse than that of monochrome cameras at about 0.15 lux.

Various methods have been tried to compensate for the shortcomings of the color camera, and a representative method is a day / night function.

It is the color bust that indicates the degree of gain of the color in the color camera.

The color burst is a sine wave pulse corresponding to a color carrier frequency (about 3.58 MHz) as a component having several cycles loaded on a color signal of an image signal, and used as a reference signal when reproducing a color signal component.

The color burst works by removing the luminance (black and white component signals of the color signal) in accordance with the illumination, without programmatically eliminating circuits.

This method uses a day / night filter, which can initially be monitored with a color camera like a black and white camera at low light (without luminance), and can capture objects at about 0.3 lux, almost similar to a black and white camera. It has better resolution than black and white cameras.

However, due to the residual components of the low-light chroma (color signal components not completely removed by the program), there is a limit in determining the resolution or the object due to the color color noise, and in the general illumination, the color may not be reproduced properly or the moire There was a problem that a bad phenomenon such as two colors overlapping) occurs.

The present invention has been made to solve the above-described problems, the object of the present invention is to monitor the environment, the user is more comfortable to watch while watching the image in color at a constant illumination (brightness of day light), In the absence of light (low light), multi-illuminance that can be used for all surveillance cameras such as indoor or external observation can be monitored for day and night by watching the image in black and white as if the user directly monitors the surrounding environment. To provide a surveillance camera.

In order to achieve the above object, the present invention is composed of a glass filter and an optical low pass filter (OLPF, Optical Low Pass Filter) when the low light conditions to change the OLPF to a glass filter in the state of removing the color burst (killing) constant illumination In the future, the company will offer a multi-illumination surveillance camera that will replace OLPF with color burst.

1 is an overall block diagram of a camera according to the present invention.

2 is a block diagram of a filter change circuit according to the present invention.

3 is a circuit diagram of an AGC control comparison unit shown in FIG. 2.

4 is a circuit diagram of the motor driving unit illustrated in FIG. 2.

FIG. 5 is a circuit diagram of the motor initial position setting unit shown in FIG. 2.

FIG. 6 is a comparator IC hysteresis curve diagram of FIG. 3.

<Description of the symbols for the main parts of the drawings>

10 Lens 12 CCD

14: CDS16: DSP

18: video driver 20: timing signal generator

22: D / A conversion unit 24: storage unit

26: color removing unit 28: motor drive unit

30: filter 30a: optical low pass filter (OLPF)

30b: transparent filter 100: AGC control comparison unit

200: motor driving unit 300: filter change motor

400: initial position setting unit 500: C signal control unit

Hereinafter, the configuration and operation of the present invention will be described with reference to the accompanying drawings.

1 is an overall block diagram of a camera according to the present invention.

The light (image) passing through the lens 10 and the filter 30 is converted into an electrical signal by the CCD 12, and the component of the image signal in the signal output from the CCD 12 is CDS (Correlated Double Sample, 14). ), And the gain of the raw video signal in the form of the extracted analog signal is controlled.

The CDS 14 removes noise components by double sampling and outputs only image information.

The filter is composed of a daytime OLPF (30a) and a nighttime transparent filter (30b) side by side, and alternately move according to the illuminance to match the lens 10 and the CCD surface.

The D / A converter 22 converts the gain-adjusted signal into an analog signal, and the storage unit 24 stores image data.

The DSP (Digital Signal Processor) 16 processes digital image data and outputs the video image signal through the video driver 18.

The timing signal generator 20 generates a timing signal necessary for each part inside the camera and sends it to each part.

The input voltage of the gain control (AGC CONT) of the CDS 14 varies depending on the illuminance. When the illuminance is large, the voltage is inversely related to the decrease.

When the AGC CONT becomes a reference voltage (for example, 2.6V (2Lux)), the output is received by the color killing block 26 and the C CONT output of the hysteresis characteristic curve shown in FIG. 6 is GND.

The C CONT output of the color remover 26 GNDs the color output signal (color burst signal C) of the DSP 16 to output a black and white video signal.

The motor driver 28 receives the C CONT output of the color remover 26 as an input and drives the motor to replace the OLPF 30a, which is the daytime filter, at the reference level (2.6V) of the CDS 14, which becomes black and white. And replace it with the transparent filter 30b which is a night filter.

The filter change method described above will be described in more detail with reference to FIGS. 2 to 6.

The filter change circuit is largely composed of an ACG control comparator 100, a motor driving unit 200, a motor initial position setting unit 400, a filter change motor 300, and a C signal controller 500.

The AGC control comparator 100 includes a comparator voltage output unit 110 formed of a comparator IC U1, a comparator reference voltage unit 120 formed of a resistor and a diode, and a burst killing unit 130 formed of a transistor Q1. And a capacitor C1.

The output AGC CONT terminal of the CDS 14 outputs a voltage of about 2.14 V or less in general illuminance, and a voltage of 3 V or less in 2.6 V or more in low light.

At this time, the comparison voltage output unit 110 is a reference voltage applied to the comparator reference voltage unit 120 and outputs a voltage depending on the hysteresis curve of FIG. 6 according to the AGC CONT voltage.

The comparator standard voltage block 120 includes an AGC CONT voltage at which the output C CONT voltage of the comparison voltage output unit varies from 3V to 0V and OV to 3V depending on the hysteresis curve as shown in FIG. Determine the AGC CONT voltage.

The capacitor C1 generates a normal output voltage such that the distorted voltage according to the hysteresis curve of the comparison voltage output unit is not output due to the output voltage of the AGC CONT that changes rapidly in a specific environment.

That is, to prevent the problem that the filter is continuously changed (OLPF 30a ⇔ glass filter 30b) by continuously supplying power to the filter change motor 300 at a certain illuminance.

According to the capacity of the capacitor C1, the camera is changed from black and white to color and from color to black and white for a certain time (about 10 seconds) when the filter is replaced.

The burst killing block 130 blocks or outputs a C (color burst) signal according to the output voltage of the comparison voltage output unit.

When the AGC control comparator 100 changes from daytime to low night with high illumination, the control gain (AGC CONT) voltage in the CDS 14 is changed from low voltage to high voltage, and the AGC CONT voltage is When 2.6V (2Lux), the output is received by the comparator IC U1 of FIG. 3 and the color burst signal control (C CONT) voltage is GND by the hysteresis characteristic curve as shown in FIG.

As a result, the signal is applied to the C signal controller 500 of the DSP 16 by the transistor Q1 to perform color killing.

That is, the color burst (C) signal is cut off and black and white.

At the same time, the C CONT voltage is input to the motor driving unit 200 of FIG. 4.

On the other hand, when the light intensity changes from low night to high day, the control gain (AGC CONT) voltage in the CDS 14 is changed from high voltage to low voltage, and when the AGC CONT voltage reaches 2.14V, the output is converted to the comparator IC of FIG. The color burst signal control (C CONT) voltage becomes 3V according to the hysteresis characteristic curve shown in FIG.

As a result, the signal is not applied to the C signal controller 500 of the DSP 16 by the transistor Q1, so that the color burst C signal is alive and becomes color.

At the same time, the C CONT voltage is input to the motor driving unit 200 of FIG. 4.

In the hysteresis curve of FIG. 6, when AGC CONT changes from a low voltage to a high voltage, the output voltage C CONT follows a-line, and when the AGC CONT changes from a high voltage to a low voltage, the output voltage C CONT follows a b-line.

The motor driving unit 200 includes an uplink voltage output unit 210 including two flip-flops U2 and U3 and a reverse rotation output unit 220 including two transistor pairs Q2 and Q3.

When the flip-flop U2 is output high according to the output voltage of the comparison voltage output unit 110, the alternate voltage output block 210 rotates forward, and the filter change motor 300 rotates forward. When the flip-flop U3 is output high, the filter change motor 300 reversely rotates.

The regular rotation and inverse rotation output block 220 amplifies the output voltage of the crossover voltage output unit 210 and prevents a malfunction of the filter change motor 300.

That is, the motor driving power is amplified so that the problem of not being replaced according to the weight or conditions of the filter change motor during the motor driving does not occur.

The motor driving unit 200 receives a control signal from the AGC control comparison unit 100 to rotate the filter change motor 300 forward or reverse to replace the OLPF 30a and the glass filter 30b.

The motor initial position setting unit 400 of FIG. 5 connected by the motor driving unit 200 ensures that the filter matching the CCD surface by the motor driving unit 200 is always the OLPF 30a when power is applied.

That is, when power is first applied, the capacitor C2 is charged and discharged, thereby driving the transistor Q4 to apply a voltage to both ends of the resistor R1, thereby causing a current to flow through the diode D1.

This current is applied to the forward rotation flip-flop U2 so that the filter change motor 300 rotates forward so that the OLPF coincides with the CCD plane.

This is to prevent the unstable screen from being output to the monitor because the position of the glass filter 30b or the OLPF 30a does not coincide with the CCD surface and is unstable in the normal state after the camera is shipped.

That is, the present invention receives the AGC CONT output of the CDS 14 from the AGC control comparator 100 and when the level of the CDS to be black and white is higher than a predetermined voltage, the filter change motor 300 for replacing the OLPF is rotated to reverse the glass. If the filter is replaced and the level of the CDS is lower than the predetermined voltage, replace the OLPF by rotating the filter change motor forward to replace the glass filter.

As described above, according to the present invention, the user monitors the image more comfortably while watching a color image at a constant illuminance (day light brightness), and monitors the image in black and white in the absence of light (low light). By watching, the user can monitor the surrounding environment as if it is the user's own environment.

Claims (7)

The image passed through the lens and the filter is converted into an electrical signal by the CCD, and the gain of the raw video signal in the form of the extracted analog signal is controlled by extracting the components of the video signal from the CDS signal output from the CCD. A surveillance camera in which video data is processed and output as a video signal; The filter is composed of an optical low pass filter (OLPF) and a glass filter arranged side by side, when the low light condition without light, the color bust is removed by the filter change means and the OLPF is replaced with a glass filter to operate as a black and white camera, the light is Color illumination is restored by the filter change means when the constant illuminance, and the glass filter is replaced by OLPF to operate as a color camera. The method according to claim 1, wherein the filter change means, A filter change motor which moves the filter in different directions by forward or reverse rotation so that the glass filter or the OLPF matches the CCD surface, An AGC control comparator for outputting a voltage of Culver Burst (C) signal control of different voltages according to the gain control (AGC CONT) voltage of the CDS and applying it to the motor driving unit and the C signal controller; A motor driving unit for driving the filter change motor forward or reversely by the C signal control; And a C signal control unit configured to block color burst by the C signal control so as to be black and white or color without blocking. The method of claim 2, wherein the AGC control comparison unit, The comparison voltage output unit configured to GND the output of the C signal control or to constantly output the voltage of the C signal control according to the AGC CONT voltage as a reference voltage of the comparator reference voltage unit; A comparator reference voltage unit for determining an AGC CONT voltage in which the output voltage of the comparison voltage output unit changes from a constant voltage to a ground voltage (0 V), and an AGC CONT voltage changing from a ground voltage OV to a constant voltage; And a burst killing unit configured to block or output a color burst signal according to an output voltage of the comparison voltage output unit. The multi-illuminance monitoring camera according to claim 3, further comprising a capacitor configured to be replaced over time at the time when the filter is replaced according to the capacity. 4. The multiple illuminance of claim 3, wherein the AGC CONT voltage at which the output voltage changes from a constant voltage to a ground voltage (0V) is 2.6V, and the AGC CONT voltage at which the output voltage changes from a ground voltage OV to a constant voltage is 2.14V. Surveillance Camera. The method of claim 2, wherein the motor driving unit, A crosslink voltage output unit configured to have two flip-flops and outputting two flip-flops selectively high according to the output voltage of the AGC control comparison unit; And a forward / reverse output unit configured to amplify the output voltage of the crossover voltage output unit and prevent a malfunction of the filter change motor. The multi-illuminance monitoring camera according to claim 2 or 6, further comprising a motor initial position setting unit configured to always match the OLPF to the CCD surface by rotating the filter change motor forward when power is applied to the camera.