JP2004229034A - Day/night camera incorporating infrared illumination - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the image quality of pictures taken at night by a day/night camera capable of outputting monitor images day and night, with respect to a monitor camera using a CCD as an imaging device. <P>SOLUTION: When discriminating it on the basis of a signal inputted from an illuminance measuring element that the brightness of a pickup object is lower than a prescribed brightness, a control part 20 performs control of removing an infrared cut filter from the front of the imaging device, selecting and outputting black-and-white signals on the basis of a signal processing result of a video signal obtained from the imaging device, and lighting infrared illumination. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surveillance camera using a CCD as an image sensor, and more particularly to a day / night camera capable of outputting a surveillance image regardless of day or night.
[0002]
[Prior art]
Using a CCD that has sensitivity in the wavelength range from visible light to infrared light, a so-called day / night camera that outputs a color image when the outside is bright and outputs a monitoring image with low illuminance as a black and white image when the outside is dark It has been put to practical use as a camera. When a color image is output, light in the infrared region is not required. Therefore, an infrared cut filter is arranged in front of the CCD so that a good image can be obtained. Japanese Patent Application Laid-Open No. H11-239356 discloses an example of such a technique.
[0003]
[Problems to be solved by the invention]
Conventional day / night cameras output daytime color images and nighttime low-light black-and-white images with a certain level of resolution. Dissatisfaction in sharpness remained.
[0004]
[Means for Solving the Problems]
According to the present invention, a day / night camera is equipped with infrared illumination so that a clear surveillance image can be output even in the darkness where the illuminance is zero, not to mention under low illuminance.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing a configuration of a day / night camera with a built-in infrared illumination according to the present invention. Reference numeral 10 denotes a lens, 11 denotes an infrared cut filter, 12 denotes dummy glass, 13 denotes an image sensor, and 14 denotes a video signal amplifier circuit. Reference numeral 15 denotes a luminance signal processing circuit that processes a luminance signal in the video signal, and reference numeral 16 denotes a color difference signal processing circuit that processes a color difference signal in the video signal. Reference numeral 17 denotes an encoder that synthesizes a video signal from a luminance signal and a color difference signal. Reference numeral 18 denotes a switching circuit for erasing the color burst signal from the video signal. If the color burst signal is cut off, the color difference signal processing circuit 16 does not operate. It is output to the outside via the encoder 17.
[0006]
Reference numeral 19 denotes a filter switching unit that inserts and removes the infrared cut filter 11 from the front of the image sensor 13. Reference numeral 21 denotes an illuminance measurement element, and a signal output from the illuminance measurement element is input to the control unit 20. Reference numeral 22 denotes an infrared light, which is composed of a plurality of infrared light emitting diodes. An illumination control circuit 23 turns on and off the infrared light 22 and controls the light emission intensity. Reference numeral 24 denotes a rectifier circuit that rectifies a signal obtained from the luminance signal processing circuit 15 and sends the rectified signal to the illumination control circuit 23. Reference numeral 25 denotes an illuminance reference setting unit that changes a reference value for brightness determination performed by the control unit 20. Reference numeral 26 denotes a shielding member provided around the lens 10 and spreading like a flange.
[0007]
When the control unit 20 of the day / night camera with the built-in infrared illumination configured as described above determines that the brightness of the imaging target is brighter than a predetermined brightness based on a signal input from the illuminance measurement element 21, the control unit 20 drives the filter switching unit 19. Then, the infrared cut filter 11 is inserted into the front surface of the image sensor. At the same time, the switching circuit 18 is controlled so that the color burst signal passes. Then, the encoder 17 combines the signals input from the luminance signal processing circuit 15 and the color difference signal processing circuit 16 and outputs a color video signal.
[0008]
When the control unit 20 determines that the brightness of the imaging target is lower than the predetermined brightness based on the signal input from the illuminance measurement element 21, the control unit 20 drives the filter switching unit 19 and causes the infrared cut filter 11 to And the dummy glass 12 is inserted instead. The dummy glass is for adjusting the optical distance to the infrared cut filter. At the same time, a signal is sent to the switching circuit 18 to control to erase the color burst signal. Here, if the color burst signal is cut off, the color difference signal processing circuit 16 does not operate, so that a monochrome video signal by only the luminance signal processing circuit 15 is output to the outside via the encoder 17.
[0009]
Further, when the control unit 20 determines that the brightness of the imaging target is lower than a predetermined brightness based on the signal input from the illuminance measurement element 21, the control unit 20 sends a signal to the illumination control circuit 23 to turn on the infrared illumination. Control. By the above series of controls by the control unit 20, a day / night camera that can obtain a clear monitoring image from a bright state in the daytime to a dark state with zero illuminance is realized.
[0010]
The lens 10 uses an auto iris lens that automatically adjusts the iris according to the ambient illuminance. In the present invention, in order to further improve the image state in a state where the image signal is switched to a black and white video signal, a luminance signal is used. After the signal obtained from the processing circuit 15 is rectified by the rectifier circuit 24, the signal is sent to the illumination control circuit 23, and the emission intensity of the infrared illumination 22 is adjusted according to the state of the luminance signal. By doing so, a more stable night vision image can be obtained by the automatic iris and the automatic adjustment of the infrared illumination.
[0011]
If a reference value for the brightness determination performed by the control unit 20 can be changed and an illuminance reference setting unit 25 for setting the reference value is provided, the value of the ambient illuminance at which the color image is switched to a black-and-white image is determined by the environment of the installation site. It can be set according to. By doing so, it is possible to meet the demands at individual installation sites, such as to delay switching to black and white images as much as possible, even if the surroundings become dark and the color screen becomes difficult to see.
[0012]
The illuminance measuring element 21 is installed so as to be buried in a flange-shaped shielding member 26 provided around the lens 10 so that the light of the infrared illumination 22 is not directly or reflected by the window of the case to be incident. I do. This stabilizes the control system for detecting the illuminance, turning on the infrared illumination, and adjusting the emission intensity of the infrared illumination.
[0013]
【The invention's effect】
According to the present invention, since the day / night camera has built-in infrared illumination, a day / night camera capable of obtaining a clear surveillance image from a bright state in daytime to darkness with zero illuminance is realized. Since the emission intensity of the infrared illumination according to the state of the luminance signal can be obtained, a more stable night-vision image can be obtained by the automatic iris and the automatic adjustment of the infrared illumination. Since the value of the ambient illuminance at which the color image is switched to the black and white image can be set according to the environment of the installation site, the usability is improved. Since the illuminance measuring element is installed so as to be buried in the shielding member provided around the lens and extending in a flange shape, light of infrared illumination is prevented from being incident, and the control system can be stabilized.
[0014]
The standard for switching between color video and black and white video is based on the signal obtained from the dedicated illuminance measurement element instead of detecting the state of the video signal. There is no need to consider, and the control is simplified. Further, since the control of the emission intensity of the infrared illumination is performed based on the state of the luminance signal, there is no coexistence with the switching control between the color image and the black and white image, and it is possible to eliminate the adverse influence between the control systems. As a result, a low-cost and stable operation assured camera is realized even though it is a day / night camera that performs complicated control, and the spread of this type of surveillance camera is promoted.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a day / night camera with a built-in infrared illumination according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Lens 11 ... Infrared cut filter 12 ... Dummy glass 13 ... Imaging element 14 ... Video signal amplifying circuit 15 ... Luminance signal processing circuit 16 ... Color difference signal processing circuit 17 ... Encoder 18 ... Switching circuit 19 ... Filter switching unit 20 ... Control unit 21 ... Illuminance measuring element 22 ... Infrared illumination 23 ... Illumination control circuit 24 ... Rectifier circuit 25 ... Illuminance reference setting unit 26 ... Shielding member

Claims (4)

Image pickup device, an infrared cut filter, insertion of the infrared cut filter in front of the image pickup device, a filter switching unit that performs extraction, an illuminance measurement element that measures the brightness of the imaging target, and infrared illumination, A lighting control circuit, and a control unit,
The control unit, when determining that the brightness of the imaging target is brighter than a predetermined brightness based on a signal input from the illuminance measurement element, drives the filter switching unit to image the infrared cut filter. The color signal is selected and output based on the signal processing result of the video signal obtained from the image sensor at the same time, and the brightness of the object to be imaged is determined based on the signal input from the illuminance measurement device. When it is determined that it is darker than the brightness of, the filter switching unit is driven, the infrared cut filter is extracted from the front surface of the image sensor, based on the signal processing result of the video signal obtained from the image sensor at the same time, A day and night camera with built-in infrared illumination, which controls to select and output a black and white signal and to turn on the infrared illumination. La. The lighting control circuit controls a light emission intensity of the infrared light according to a strength of a signal obtained from a luminance signal processing circuit among signals obtained from the imaging device. 2. The day / night camera with built-in infrared illumination according to 1. The illuminance reference setting unit that changes a reference value for brightness determination performed by the control unit, wherein the control unit performs control based on a setting value of the illuminance reference setting unit. Item 4. A day / night camera with built-in infrared illumination according to item 2. The illuminance measurement element is provided so as to be buried in a flange-shaped shielding member provided around the lens of the imaging element, and the light of infrared illumination is directly or reflected by a window of a case and does not enter. The infrared / illumination built-in day / night camera according to claim 1, wherein:

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