KR19990085958A - Closed Circuit Camera with Improved Sensitivity - Google Patents

Abstract

CCD device which converts video signal into electrical signal and outputs it, removes clock signal from CCD signal output signal, detects only pure video signal component, and automatically gains to have constant signal level against ambient light change After control, the luminance signal and the color signal are separated from the image hold / auto gain / analog digital converter and the image signal input from the sample hold / auto gain / analog digital converter. A digital signal processor for processing luminance signal components such as contrast and pedestal and color signal components such as white balance, a vertical driver for buffering and outputting vertical and horizontal clock signals for driving CCD elements provided by the digital signal processor; Detects when the output signal of the digital signal processor falls below a certain level. A microcontroller for outputting a control signal for operating the switch circuit of the amplifier and switch, an amplifier and switch for amplifying the luminance signal and outputting the amplified signal according to the signal of the microcontroller, and supplied from the amplifier and the switch. It consists of an encoder that generates the composite video signal, which is the final video output signal by receiving the luminance signal and the color signal, and an EEPROM that stores the information necessary to operate the camera. By providing more than twice the current level, it provides CCTV cameras with improved sensitivity characteristics, which enhances sensitivity for use in dark environments that cannot be observed with existing products.

Description

Closed Circuit Camera with Improved Sensitivity

The present invention relates to a closed-circuit camera (hereinafter referred to as a "CCTV camera") with improved sensitivity characteristics. More specifically, an existing product is manufactured by increasing the sensitivity of a CCTV camera more than twice as much as the current level while processing images in real time. The present invention relates to a CCTV camera with improved sensitivity characteristics, which can be used in a dark environment where it cannot be observed.

In general, in order to monitor or monitor a space in a specific area, a closed-circuit monitoring system combining a closed-circuit television (CCTV) camera such as a CCD (Charge Coupled Device) camera and a monitor for a closed circuit is used. Two CCTV cameras are used, namely, color analog and digital.

Hereinafter, a conventional CCTV camera will be described with reference to the accompanying drawings.

1 is a configuration diagram of a conventional color analog CCTV camera, the signal output from the CCD element 10 is the system of the sample hold / automatic gain unit 20, the processor 30, and the encoder 40 Signal processing flow is achieved by outputting signals. The CCD device 10 converts an image into an electrical signal, and outputs a signal from several mV to several hundred mV due to the magnitude of the signal depending on the ambient illumination. On the other hand, the AGC circuit of the sample hold / auto gain unit 20 has a constant size in the form of a signal regardless of the change in illuminance so that the output signal of the CCD element 10 having a different signal size according to the change in ambient illuminance can be easily observed on the monitor. Create and print The vertical driving unit 60 provides the CCD device horizontal and vertical driving signals for driving the CCD device 10 from the clock signal generated by the timing generator 50. Output the signal accumulated in each cell.

The 1H delay unit 80 and the chroma 1H delay unit 90 have a role of correcting a delay time in the high pass filter of the color signal in the processor 30 and a time difference generated in the AGC amplification and color signal demodulation circuits.

The encoder 40 generates a luminance signal, a color signal output from the processor 30, and a composite synchronization signal provided from the synchronization signal generator 70 to generate a composite video signal, which is a final video output signal. It provides a composite video signal synthesized with a luminance signal, a color signal, and a synchronization signal.

In such a color analog system, the gains of the CCD element 10, the AGC circuit of the sample hold / auto gain unit 20, and the processor 30 can be determined. The sensitivity of the CCD element 10 depends on the size of the chip. On the other hand, the AGC circuit of the sample hold / auto gain unit 20 and the gain of the processor 30 exhibit almost the same characteristics for each manufacturer, which monitors the signal from the CCD element 10 under normal conditions. This is because the AGC circuit of the sample hold / auto gain unit 20 and the gain of the processor 30 are determined so as to be easily observed.

After all, the sensitivity of CCTV cameras depends on how large and good CCD devices are used.However, due to the limitations (part size) and price of CCD structures, the sensitivity characteristics of CCD devices used in industrial applications are It is differentiated within 10% to 20%.

2 is a configuration diagram of a conventional digital CCTV camera, unlike the analog CCTV camera of FIG. 1, the analog digital converter 100 and the digital signal processor 110 for signal processing in a digital manner It has a built-in structure.

In the digital CCTV camera as well as the analog CCTV camera, the sensitivity characteristics of the CCTV camera are determined by the gains of the CCD element 10, the AGC 20, and the digital signal processor 110.

In other words, the device used in the digital camera also has the same gain characteristics as the components of the analog camera, so as a result, the conventional analog or digital CCTV camera is almost the same level as any company product. It has sensitivity characteristics, and sensitivity is determined by gain characteristics provided by IC components.

In general, one of the most important characteristics of CCTV cameras depends on the sensitivity characteristic of how dark the object can be identified.

However, the sensitivity of conventional CCTV cameras depends on the gain characteristics of CCD devices, AGCs, and processors. Therefore, when manufacturing CCTV cameras using these components, the sensitivity characteristics depend entirely on the component characteristics. There is a very difficult problem.

Although recent methods have been commercialized to increase the sensitivity of CCTV cameras by accumulating CCD signals for a certain amount of time, these methods accumulate a certain amount of time, making it impossible to process real-time images. When processing an image in real time, it has to have the same sensitivity characteristics as the conventional method, and since it requires many components such as a memory device, there is a disadvantage in terms of cost.

An object of the present invention is to solve the conventional problems as described above, while processing the image in real time, by increasing the sensitivity of the CCTV camera more than two times higher than the current level can be used in a dark environment that cannot be observed with existing products. It is to provide a CCTV camera with improved sensitivity, so that the sensitivity is improved.

1 is a block diagram of a conventional color analog CCTV camera.

2 is a block diagram of a conventional digital CCTV camera.

3 is a block diagram of a CCTV camera having improved sensitivity characteristics according to the first embodiment of the present invention.

4 is a detailed circuit diagram illustrating an amplifier and a switching unit of a CCTV camera having improved sensitivity characteristics according to the first embodiment of the present invention.

5 is a detailed circuit diagram of a monochrome CCTV camera having improved sensitivity characteristics according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: CCD element 20: sample hold / auto gain part

30: processor 40, 170: encoder

50: timing generator 60: vertical drive unit

70: synchronization generating unit 80: 1H delay unit

90: chroma 1H delay unit 100: analog log converter

110,150: digital signal processor 120: timing / synchronization generator

130,180: microcontroller 140: sample hold / auto gain / analog digital converter

160: amplifier and switching unit 190: EEPROM

As a means for achieving the above object, the configuration of the present invention comprises a CCD element for converting and outputting an image signal into an electrical signal, and removing the clock component signal from the signal output from the CCD element, and removing the component of the pure video signal. And a sample hold / auto gain / analog digital converter which detects only and converts the digital signal into a digital signal for signal processing in a digital manner after automatic gain control to have a constant signal level with respect to ambient illumination changes. A digital signal processor for processing luminance signal components such as image quality, contrast, and pedestal, and processing color signal components such as white balance by separating luminance signals and color signals from digital image signals input from the hold / auto gain / analog digital converter unit; Vertical and horizontal clock for driving CCD elements provided by the digital signal processor A vertical controller that buffers the signal and supplies it to the CCD element, a microcontroller that detects when the output signal of the digital signal processor falls below a predetermined level and outputs a control signal for operating the switch circuit of the amplifier and the switch, and a luminance signal An amplifier and switching unit for amplifying and outputting an amplified signal according to the signal of the microcontroller, an encoder for receiving a luminance signal and a color signal supplied from the amplifier and switching unit and generating a composite video signal as a final video output signal; It includes an EEPROM that stores information necessary to operate the camera.

As a means for achieving the above object, another configuration of the present invention is a CCD element for converting and outputting an image signal into an electrical signal, and removing the clock component signal from the signal output from the CCD element, Sample hold / auto gain / signal processing unit that detects only and automatically processes gain of brightness, such as image quality, contrast, and pedestal, to have a constant signal level against changes in illuminance. A timing synchronizing unit for providing a clock, a vertical driving unit for receiving and buffering the vertical and horizontal clocks for driving the CCD elements provided by the timing synchronizing unit to drive the CCD element, and an output of the sample hold / auto gain / signal processing unit Compares the video signal with the reference voltage and detects when the voltage is below a certain voltage. A level detector for outputting a control signal for driving, and an amplifier and switching unit for receiving a video signal from the sample hold / auto gain / signal processing unit and amplifying and outputting luminance in a low light environment according to the control signal of the level detector. It is done by

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. Shall be.

3 is a block diagram of a CCTV camera having improved sensitivity characteristics according to the first embodiment of the present invention. As shown in FIG. 3, the configuration of a CCTV camera having improved sensitivity characteristics according to the first embodiment of the present invention includes a CCD device 10 for detecting an image and converting the image into an electrical signal, a sample hold and an automatic gain control unit; The sample hold / auto gain / analog digital converter unit 140, which integrates the function of the analog log converter, and the digital signal which separates the luminance signal and the color signal from the work signal and processes the luminance signal component and the color signal component. A processor 150, a vertical driver 60 for buffering and outputting vertical and horizontal clock signals for driving a CCD element, and an amplifier and switch unit for amplifying and outputting 6 dB of luminance signals according to a control signal of the microcontroller 180 ( 160, an encoder 170 for generating and outputting a composite video signal, an EEPROM 190 for storing information necessary for the user to operate the camera, and a built-in software program. Sikimyeo executing various functions of the camera by the addition is made to the microcontroller 180 has a function of controlling the operation of each part.

4 is a detailed circuit diagram illustrating an amplifier and a switching unit of a CCTV camera having improved sensitivity characteristics according to the first embodiment of the present invention. As shown in FIG. 4, the amplifier and the switching unit of the CCTV camera having the improved sensitivity characteristics according to the first embodiment of the present invention may be configured through the buffer transistor Q1 through the output signal YOUT of the digital signal processor 150. The 6dB amplifier is connected, and the switch circuit is connected to the output terminal of the 6dB amplifier and the output signal DS of the microcontroller 180.

The operation of the CCTV camera having improved sensitivity characteristics according to the first embodiment of the present invention by the above configuration is as follows.

The CCD device 10 converts an image into an electrical signal and outputs a signal ranging from several mV to several hundred mV according to the ambient light intensity and outputs a signal from several mV to several hundred mV. In order to easily observe the signal of 10), the AGC circuit of the sample hold / auto gain / analog digital converter unit 140 outputs a signal having a constant size regardless of the illuminance change.

The signal from the CCD device 10 is converted into a digital signal through the sample hold / auto gain / analog digital converter 140 and is input to the digital signal processor 150.

The digital signal processor 150 communicates with the microcontroller 180 and performs various signal processing digitally by a control program embedded in the microcontroller 180.

Although the automatic voltage gain control of the sample hold / auto gain / analog digital converter 140 is set as a condition of the maximum voltage gain, it is difficult to observe an object on a monitor at a very low CCD signal output. Therefore, in a dark environment or a situation in which the aperture of the lens is closed very much, there is a problem that the sensitivity of the camera cannot be raised by the conventional method. In the present invention, the signal is detected by the digital signal processor 150 so as to increase the sensitivity even in a dark environment where the CCD signal is output very low, and the amplification and output through the 6dB (double) amplifier in the amplifier and switch unit 160 and In a constant light environment, the switch circuit is switched to output the light through the 6dB amplifier without removing the possibility of signal saturation at a constant light intensity.

That is, in the present invention, as shown in Figure 3, the amplifier and the switching unit 160 consisting of a 6dB amplifier and a switch circuit is inserted between the processor and the encoder, which is an existing system configuration, to minimize the use of parts and control operation Digital control was adopted to improve the efficiency of the system.

Since the microcontroller 180 always communicates with and controls the digital signal processor 150, the microcontroller 180 detects the signal output of the digital signal processor 150 in a dark environment.

The output signal of the digital signal processor 150 is detected by the microcontroller 180 through the SDO pin, and when the ambient light becomes dark, the output signal of the digital signal processor 150 is also lowered. The controller 180 detects this and outputs a control signal DS in a high state. That is, when the signal is output from the digital signal processor 150 to the amplifier and the switching unit 160 below the reference value corresponding to the dark environment, the microcontroller 180 sends the control signal DS to the amplifier and the switching unit 160. By outputting and operating the switch circuit, the output of the 6dB amplifier is output through the switch circuit so that the signal amplified twice compared to the existing signal is output as the video output through the encoder 170.

However, under a certain level of illumination, since the signal output of the digital signal processor 150 is greater than or equal to the reference value, the microcontroller 180 does not operate the switch circuits of the amplifier and the switching unit 160, so that the video signal output does not saturate. The sample hold / auto gain / analog digital converter 140 appears on the monitor as a constant level signal according to the operation of the AGC circuit.

The operation of the amplifier and switching unit 160 will be described in more detail with reference to FIG. 4 as follows.

The output signal YOUT of the digital signal processor 150 passes through the low pass filter and the buffer transistor Q1 and is then connected to the 6dB amplifier and the switch circuit. The signal passing through the buffer transistor Q1 is connected to the switch circuit via two paths. One is a first input connected through a capacitor C14 without going through a 6dB amplifier, and the other is a second input connected through a capacitor C13 and a 6dB amplifier and a capacitor C15. The first input is a path through which the output signal of the digital signal processor 150 is transmitted as it is, and the second input is a path through which the output signal of the digital signal processor 150 is amplified by 6 dB (doubled). These first and second input signals are connected to pin 1 (IN1) and pin 2 (IN2) of the video switch, and in the video switch, the first or second input is performed by the control signal DS from the microcontroller 180. It will output one of the signals.

In the operation of the video switch, when the control signal DS applied to the control pin CTL is high, the second pin IN2 signal of the second input is output, and the control signal applied to the control pin CTL. When (DS) is in a low state, the first pin (IN1) signal of the first input is output.

When the peripheral illumination becomes dark and the output signal of the digital signal processor 150 falls below a certain level, the microcontroller 180 detects this and emits the control signal DS of the video switch to a high state. The internal switch of the video switch is switched to pin 2 (IN2) which is the second input by being input to the video switch via the resistor R13. In this way, the output signal of the digital signal processor 150 is eventually increased by 6 dB and then output, and is then output as the final video signal via the encoder 170.

In addition, when the peripheral illuminance again becomes higher than a predetermined illuminance, the output signal of the digital signal processor 150 also increases, and when the output signal of the digital signal processor 150 increases above a predetermined level, the microcontroller 180 outputs a video output signal. In order to prevent the saturation of the video signal, the control signal DS of the video switch is output in a low state, so that the output signal of the digital signal processor 150 is provided to the rear circuit as a general signal level level through the capacitor C14.

In this way, the function of automatically detecting the output signal level of the digital signal processor 150, and by using the 6dB amplifier and video switch to increase the voltage gain of the CCD signal more than twice in low light environment to improve the sensitivity characteristics compared to conventional products It can be increased more than 2 times and it has a function of automatic sensitivity switching corresponding to the change of ambient light.

The present invention can be used in any apparatus for observing an image using a CCD element. 5 is a block diagram of a monochrome CCTV camera having improved sensitivity characteristics according to a second embodiment of the present invention. The system configuration of the monochrome CCTV camera with improved sensitivity characteristics according to the second embodiment of the present invention is very simple. That is, in the monochrome CCTV camera system having improved sensitivity characteristics according to the second embodiment of the present invention as shown in FIG. 5, the basic configuration is the sample hold / auto gain / signal processing unit 200 in addition to the CCD element 10. And the three main IC components of the level detector 210, the amplifier and the switching unit 160. In order to apply the inventive concept in such a simple configuration, the level detector 210 is additionally required in addition to the 6 dB amplifier and the video switch of the amplifier and the switching unit 160.

With the above configuration, the operation of the monochrome CCTV camera with improved sensitivity characteristics according to the second embodiment of the present invention is as follows.

When the signal is output from the CCD element 10, the AGC circuit of the sample hold / auto gain / signal processing unit 200 is adapted to the change in the illuminance so as to easily observe the signal of the CCD element 10 having a different signal size according to the change in ambient illumination. Regardless of the size, make sure that a certain amount of signal is output

The output level of the signal is detected by combining the level detector 210 using the comparator or the like from the output of the sample hold / auto gain / signal processing unit 200, and the amplifier and the switching unit are output to the comparator of the level detector 210. By driving the video switch of 160, the same concept as in the first embodiment of the present invention can be applied to a black and white CCTV camera system or another system using a CCD element.

As described above, in the embodiment of the present invention, the sensitivity of the CCTV camera is increased by more than twice the current level while processing the image in real time, thereby improving the sensitivity to be used in a dark environment that cannot be observed with existing products. A closed circuit camera with improved excitation sensitivity can be provided. This effect of the present invention may be modified and used by those skilled in the art without departing from the gist of the present invention in the field of CCTV cameras.

Claims (3)

CCD device for converting and outputting video signal into electrical signal, and removing clock signal from the signal output from the CCD device, detecting only the pure video signal, and having a constant signal level for the change in ambient light. Sample hold / auto gain / analog digital converter which converts and outputs a digital signal for digital signal processing after automatic gain control, and digital image input from the sample hold / auto gain / analog digital converter. A digital signal processor for separating luminance signals and color signals from the signals and processing luminance signal components such as image quality, contrast, and pedestal, and color signal components such as white balance, and the vertical and horizontal driving of CCD elements provided by the digital signal processor. A vertical driver for buffering a clock signal and supplying it to the CCD; A microcontroller that detects when the output signal of the frame signal processor falls below a predetermined level and outputs a control signal for operating the switch circuit of the amplifier and the switching unit, and amplifies the luminance signal and amplifies the signal according to the signal of the microcontroller An amplifier and switching unit for outputting a signal, an encoder for receiving a luminance signal and a color signal supplied from the amplifier and switching unit, and generating a composite video signal as a final video output signal; and an EEPROM storing information necessary for operating a camera. Closed circuit camera with improved sensitivity characteristics, characterized in that comprises The method of claim 1, The amplifier and the switching unit, the output signal of the digital signal processor via a buffer transistor, the 6dB amplifier is connected, and the switch circuit is connected to the output terminal of the 6dB amplifier and the output signal of the microcontroller is characterized in that the sensitivity Closed circuit camera with improved characteristics CCD device that converts video signal into electrical signal and outputs it, and removes clock signal from signal output from the CCD device and detects only pure video signal component, and automatically has constant signal level with respect to peripheral illumination change. A sample hold / auto gain / signal processing unit for processing and outputting luminance signals such as image quality, contrast, and pedestal after gain control, a timing synchronization generator for providing various clocks necessary for the operation of the camera, and the timing synchronization generator A vertical driver for driving the CCD device by receiving and buffering the supplied vertical and horizontal clocks for driving the CCD device, and comparing the output video signal of the sample hold / auto gain / signal processing unit with a reference voltage to detect a predetermined voltage below a predetermined voltage. And a level detector for outputting a control signal for operating the switch circuit of the switching unit, and the sample hole. A closed circuit having improved sensitivity characteristics, comprising: an amplifier and a switching unit which receives a video signal from a signal / auto gain / signal processing unit and amplifies and outputs luminance in a low light environment according to a control signal of the level detector. camera