KR101475468B1 - Infrared camera system with infrared LED - Google Patents

Abstract

The present invention relates to an infrared LED camera system,
An infrared LED array in which a plurality of infrared LEDs are arranged and arranged so as to face the photographing direction of the camera, an image pickup device unit for converting the image inputted through the camera lens into an electric signal, And an infrared LED control unit for controlling a light output of the infrared LED array based on the digital image data output from the image signal processing unit, An infrared LED camera system, wherein the infrared LED control unit controls the infrared LED array so that the total light output of the infrared LED array is maintained within a range in which the image is not saturated, and is determined to have brightness lower than a predetermined reference value in the entire area of the image Area of the infrared LED array The light transmitting the output of the infrared LED is set to a light transmitting area per characterized in that the control to more increase.

Description

[0001] The present invention relates to an infrared LED camera system,

The present invention relates to an infrared LED camera system, and more particularly, to an infrared LED camera system used for nighttime monitoring, in which an infrared LED light emission control is separately performed on a subject and a back background through image analysis, The present invention relates to an infrared LED camera system configured to be able to prevent a hunting phenomenon when an LED is turned on / off so that a clear nightly surveillance image can be obtained with respect to both a subject and a background.

A CCTV (Closed Circuit Television) camera generally used for surveillance purposes uses sunlight in the daytime and a separate lighting means such as an infrared LED (Light Emitting Diode) at night.

Since the infrared LED camera uses the infrared LED as the lighting means, the camera does not see the light in the naked eye when shooting at night, but the camera can detect the infrared light and shoot the subject clearly.

Since such an infrared LED camera uses infrared LED lighting, not general lighting, its use is spreading to an underground parking lot or a public place at night where illumination does not need to be brightened.

However, when the subject is too close to the infrared LED camera, the captured image may become saturated and the subject may not be able to be identified.

As an example of a conventional technique for solving such a problem, there has been attempted a method of adjusting a camera exposure state through an AE (Auto Exposure) function of a camera to make a close object appear clearer.

However, such an exposure adjustment method has a disadvantage in that a close subject can be made visible by the AE adjustment, but the background is darker, making shooting difficult. In video surveillance, shooting of main subjects is also important, but since the surrounding images corresponding to the background are often important, these disadvantages have been a limiting factor in practical applications.

As another example of the related art, a method of adjusting the dimming of the infrared LED array using PWM (Pulse Width Modulation) control has been attempted.

However, such a control method has a limitation in clearly capturing both the subject and the background because the infrared LED array is turned on and off as a whole.

Korean Patent No. 10-1228338 (registered on Jan. 25, 2013) has been proposed as an example of related prior art. The prior art includes an infrared LED control unit that illuminates corresponding LEDs among a plurality of infrared LEDs when a subject included in the image data is dark. However, in the prior art, But it still has a limitation in that it can not propose a configuration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an infrared LED camera system which is used for night-time monitoring, in which an infrared LED floodlighting control is separately performed on a subject and a back- And an object of the present invention is to provide an infrared LED camera system configured to be able to prevent a hunting phenomenon at the time of ON / OFF of an infrared LED, so that a clear nightly surveillance image can be obtained with respect to both a subject and a background.

According to an aspect of the present invention, there is provided an infrared LED array including a plurality of infrared LEDs arrayed to face a photographing direction of a camera, An image signal processor for converting an electrical signal transmitted from the image pickup element into a digital image signal and performing a digital image signal processing; An infrared LED camera system configured to include an infrared LED controller for controlling a light output of an infrared LED array, wherein the infrared LED controller controls the total light output of the infrared LED array to be maintained within a range in which the image is not saturated, The brightness of the entire region of the image is lower than a predetermined reference value The infrared LED camera system, characterized in that the control such that the light-transmitting output of the infrared LED is set to the light-transmitting region of the infrared LED array even higher is disclosed for the area that might be.

Preferably, the infrared LED control unit divides the entire area of the image into a plurality of unit areas, sets a control area composed of at least one unit area, and sets the control area corresponding to each control area based on the brightness of each control area And can be configured to individually control the light output of the infrared LED.

Preferably, the control area is set to be composed of a plurality of unit areas, and the first average value of the brightness of the plurality of unit areas included in each control area is calculated, and the first average value is calculated for the corresponding control area The light output of the infrared LED may be individually controlled.

Preferably, a first average value of each control area included in the reference image frame and a predetermined number of consecutive frames temporally preceding the reference image frame are compared with each other based on an image frame corresponding to a light emission output control time point of the infrared LED array A second average value of the first average values of the same control regions included in the control region is calculated and the light output of the infrared LED corresponding to the control region is individually controlled based on the second average value.

Preferably, the range of the light transmitting region of the infrared LED can be adjusted by adjusting the focus of the light projecting control lens provided on the front surface of the infrared LED array, or adjusting the view angle of the infrared LED array.

According to the present invention, infrared LED light emission control is separately performed on a subject and a back background through image analysis in nighttime monitoring of an infrared LED camera system, so that a clear night vision image . ≪ / RTI >

In addition, it is possible to prevent the hunting phenomenon when the infrared LED is turned on / off, thereby providing an advantage that the infrared LED floodlight control can be performed stably.

1 is an overall configuration diagram of a general video security system,
2 is a block diagram of an infrared LED camera system according to an embodiment of the present invention;
3 is a detailed block diagram of a video signal processor and an infrared LED controller according to an embodiment of the present invention.
4 is an exemplary layout of LEDs of an infrared LED array according to an embodiment of the present invention,
5 is a diagram illustrating an example of the layout of LEDs of an infrared LED array according to another embodiment of the present invention.
6 is a configuration diagram of an infrared LED driving circuit according to an embodiment of the present invention,
7 is a configuration diagram of an infrared LED driving circuit according to another embodiment of the present invention,
8 is a diagram illustrating an example of a video area setting according to an exemplary embodiment of the present invention.
9 is a diagram illustrating an example of a video area setting according to another embodiment of the present invention.
10 is a diagram illustrating an example of a video area setting according to another embodiment of the present invention.
11 is a conceptual diagram for explaining a second average value calculation process according to another embodiment of the present invention,
12 is a schematic diagram for explaining the setting of the range of the light transmitting region of the infrared LED using the light transmission control lens according to the embodiment of the present invention,
13 is a schematic view for explaining the range setting of the light transmitting region of the infrared LED using the light transmission control lens according to another embodiment of the present invention,
FIG. 14 is a schematic diagram for explaining the range setting of the light emitting region of the infrared LED using the view angle adjustment according to the embodiment of the present invention,
FIG. 15 is a schematic view for explaining the range setting of the light transmitting region of the infrared LED using the view angle adjustment according to another embodiment of the present invention;
16 is a block diagram showing the ITU video data standard.

The present invention may be embodied in many other forms without departing from its spirit or essential characteristics. Accordingly, the embodiments of the present invention are to be considered in all respects as merely illustrative and not restrictive.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises", "having", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, components, Steps, operations, elements, components, or combinations of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and a duplicate description thereof will be omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a general image security system, which illustrates an image security system to which the infrared LED camera system of the present embodiment is applied.

A camera 200 for capturing an image of a monitoring object, an image storing means 30 for storing the captured image, and a control means 100 for controlling the operation of the camera 200 or the image storing means 30 A video security system is constructed.

A solid line 50 indicates a video signal transmission line using a coaxial cable or the like, and a dotted line 60 indicates a control signal transmission line using a serial communication cable. The power line is not separately shown for the sake of explanation.

In the case of a UTC (Up-the-Coax) camera, a video signal transmission and a control signal transmission may be performed together using a coaxial cable, so that a serial communication cable may not be separately provided.

Since a plurality of such image security systems have already been known, a detailed description thereof will be omitted.

FIG. 2 is a block diagram of an infrared LED camera system according to an embodiment of the present invention. FIG. 3 is a detailed block diagram of an image signal processor and an infrared LED controller according to an embodiment of the present invention. FIG. 5 is a diagram illustrating an exemplary layout of LEDs of an infrared LED array according to another embodiment of the present invention.

The infrared LED camera system of this embodiment is provided with an infrared LED array 202 in which a plurality of infrared LEDs are arranged and arranged so as to face the photographing direction of the camera 200. [ The infrared LED array 202 may be a SMD (surface-mounted device) type in which a plurality of infrared LED chips are mounted as illustrated in FIG. 4, and a plurality of infrared LED lamps may be mounted Gt; lamp < / RTI > type. FIG. 5 is an infrared LED array 202 applied to a bullet-type camera, and a hollow portion is formed so that a camera lens can be installed through the center.

In addition, the infrared LED array 202 may be divided into a plurality of sub-arrays 2022 to 2026 as the most basic operation mode, May be separately installed or controlled. FIG. 2, FIG. 4, or FIG. 5 illustrate the arrangement of the individual infrared LEDs, together with the arrangement of sub-arrays that can be implemented by the modification. In this case, the arrangement type and number of the subarrays 2022 to 2026 and the like can be set corresponding to the size, direction, and number of areas of the image captured by the camera. For example, when a plurality of control areas (Area 1, 2, 3, ...) are set as the whole area of the image as shown in FIG. 9, the infrared LED array 202 The sub-arrays 2022, 2024, 2026, ... can be set. FIG. 6 is a block diagram of an infrared LED driving circuit (in the case of matrix control) according to an embodiment of the present invention, and FIG. 7 is a block diagram of an infrared LED driving circuit As a constitutional diagram, the infrared LED array 202 may be driven by an infrared LED driving circuit as illustrated in Fig. 6 or Fig. It can also be understood that the infrared LED driving circuit corresponds to the TR array 202a of Fig.

The infrared LED camera system of the present embodiment further includes an imaging element unit 210 that converts an image incident through the camera lens 204 into an electrical signal and an electric signal transmitted from the imaging element unit 210 A video signal processing unit 208 for converting the digital video signal into a digital video signal and performing a digital video signal processing, and a video signal processor 208 for controlling the light output of the infrared LED array 202 based on the digital video data output from the video signal processor 208 An infrared LED control unit 206 is provided. The image pickup element unit 210 generally converts an image into an analog signal and the image is converted into a digital signal according to the characteristics of the image pickup element unit 210. [

For example, a well-known CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor can be used as the imaging element unit 210.

The image signal processing unit 208 may be regarded as performing a function similar to a known ISP (Image Signal Processor). The image signal processing unit 208 converts an electrical signal transmitted from the image pickup device unit 210 into a digital image signal, And performs signal processing. Examples of such digital image signal processing include gamma correction, interpolation, spatial conversion, image effect, image scale, AWB (Auto White Balance), AE (Automatic Exposure), AF (Automatic Focus), and the like. The digital image data output from the image signal processing unit 208 may be RGB data or YCbCr data according to the configuration of the image signal processing unit 208. [

The infrared LED control unit 206 may be similar to a known digital signal processor (DSP) or a field programmable gate array (FPGA) And controls the light output of the infrared LED array 202 on the basis of the light output from the infrared LED array 202.

The infrared LED control unit 206 analyzes digital image data (ITU-R standard or non-standard digital image data) having various resolutions. For example, when H-Sync, V-Sync, and Field signals are provided, the start of active video (SAV), end of active video (EAV), Field, and V-Sync are discriminated . When various sync signals Sync are embedded in the digital video data, the digital video data is analyzed to determine SAV, EAV, Field, and V-Sync.

The infrared LED control unit 206 of the present embodiment performs the control so that the total light output of the infrared LED array 202 becomes high within a range in which the image is not saturated based on the image output from the image signal processing unit 208, Control is performed such that the light output of the infrared LED set to emit light in the corresponding area of the infrared LED array 202 is controlled to be higher for an area determined to have brightness lower than a predetermined reference value among the entire area of the image.

Here, the term 'maintaining and controlling the total light output of the infrared LED array 202 to be high within a range in which the image is not saturated' means that the total light output of the infrared LED array 202 for the entire region of the image is increased When it is detected that saturation occurs in a specific area based on the digital image data output from the image signal processing unit 208, it can be understood that the control is performed in such a manner that the total light output is lowered to an appropriate level so that the saturation of the area is eliminated have.

While maintaining the total light output of the infrared LED array 202 so that the total brightness of the image is maximized within the range where saturation does not occur, the total light output of the infrared LED array 202 is maintained in an area determined to have brightness lower than a predetermined reference value Control is performed so that the light output of the infrared LED set to emit light in the corresponding area of the infrared LED array 202 becomes higher, and the brightness of the corresponding area is individually increased. The light emission output of the infrared LED can be made, for example, through current amount control or ON / OFF control. As a result of this control, it is possible to obtain the brightest and brightest nightly surveillance image within the range in which saturation does not occur over the entire area.

In an example of a configuration that can be practically implemented for commercial products, the saturation of the image is determined by referring to the AE (Auto Exposure) value output from the image signal processing unit 208, and by controlling the infrared LEDs so as not to saturate the image . ≪ / RTI > At this time, the infrared LED control unit 206 stores the AE level, and maintains the illuminance within a range in which saturation is not achieved with respect to the saturation part.

The 'brightness' of the image may be obtained, for example, by analyzing the luminance signal among digital image data output from the image signal processor 208. FIG. 16 is a block diagram showing the ITU image data standard. Referring to FIG. 16, only the Y signal among the luminance data (Y) and color difference data (Cb, Cr) data is selectively used for analysis.

If data is not transmitted as a luminance signal and a color difference signal but is output as RGB data, luminance data may be extracted by the following calculation method. The coefficients of Equation (1) may be variously changed according to the encoding scheme.

On the other hand, the reference value used for determining the low brightness area of the whole area of the image can be appropriately set in consideration of the brightness and sharpness of the required image.

FIG. 8 is a diagram illustrating an example of a video area setting according to an exemplary embodiment of the present invention. FIG. 9 is a view illustrating an exemplary video area setting according to another exemplary embodiment of the present invention. Fig.

8 to 10, the infrared LED control unit 206 divides and sets the entire area of the image into a plurality of unit areas Y1-1, Y1-2, ..., and at least one A control area formed of a unit area may be set, and the light output of the infrared LED corresponding to each control area may be individually controlled based on the brightness of each control area. 8 to 9, the first control area (Area 1) includes Y1-1 to Y1-4, Y2-1 to Y2-4, Y3-1 to Y3-4, and Y4-1 to Y4 -4, and the remaining control areas (Area 2, 3, ...) may be configured in the illustrated form.

At this time, although the actual shape of the area where the actual infrared LED array 202 or the individual infrared LEDs affect the brightness may be regarded as a circle, the setting of the control area may be set to a rectangle. Also, as illustrated in Fig. 10, it is also possible to set the control area to be partially overlapping. That is, the size of the control region to be used may be changed according to the projection angle of the infrared LED array 202 or the individual infrared LEDs constituting the infrared LED array 202 (this is referred to as a view angle for convenience) Overlapping may occur in control regions that affect them.

As described above, the control area is set to include a plurality of unit areas. The control area calculates a first average value of brightness of a plurality of unit areas included in each control area, and calculates a first average value The light output of the infrared LED corresponding to the control area can be separately controlled.

For example, in the case of the first control area (Area 1), 16 units of Y1-1 to Y1-4, Y2-1 to Y2-4, Y3-1 to Y3-4, and Y4-1 to Y4-4 Calculates a first average value for each brightness (luminance) measured for each region, determines that the first average value is the brightness of the first control region (Area 1), and based on this, (Area 1) of the infrared LED.

11 is a conceptual diagram for explaining a second average value calculation process according to another embodiment of the present invention.

11, on the basis of the image frame (Frame 1) corresponding to the light emission output control time point (or the time point synchronized with the light emission output control time) of the infrared LED array 202, Included in a predetermined number of consecutive frames (Frame 2, 3, 4) temporally preceded by a first average value of each control area (Area 1, 2, 3, Calculates a second average value for the first average values of the same control areas (Area 1, 2, 3, ...), and outputs the light output of the infrared LED corresponding to the control area based on the second average value . Here, the image frames sequentially generated in time may be used as they are, but the selected image frames may be used at predetermined time intervals according to the setting.

For example, when controlling the light output of the infrared LED array 202 for each of the image frames, a phenomenon in which the infrared LED is turned on and off too frequently, that is, a hunting phenomenon may occur.

In the present embodiment, the first average value for each control region is used to prevent frequent ON / OFF of the individual infrared LEDs, and for the first average values of the same control regions included in the predetermined number of consecutive frames, And a second average value is calculated and used for control to prevent the hunting phenomenon for each control area unit.

In other respects, it can be understood that the image frames Frame 2, 3, 4 which temporally precedes the infrared LED light emission control at the synchronization point of the image frame Frame 1 serve as a buffer. For example, it can be understood that the image frames Frame 3, 4 and 5 temporally preceding the image frame Frame 2 serve as a buffer.

With this configuration, the infrared LED light emission control can be performed more stably without hunting phenomenon.

FIG. 12 is a schematic view for explaining the setting of the range of the light transmitting region of the infrared LED using the light projecting control lens according to the embodiment of the present invention, and FIG. 13 is a cross- Fig. 14 is a schematic view for explaining the range setting of the light-transmitting area of the infrared LED using the view angle adjustment according to the embodiment of the present invention, Fig. 15 is a schematic view for explaining setting of the light- Fig. 7 is a schematic diagram for explaining the range setting of the light emitting region of the infrared LED using the view angle adjustment according to the embodiment. In each drawing, (b) shows a camera screen.

The range of the light transmitting region of the infrared LED can be adjusted by adjusting the focal point of the light transmission control lens 300 provided on the front surface of the infrared LED array 202 or adjusting the view angle of the infrared LED array .

In order to control the infrared LED array 202 as described above, for example, it is preferable that the range of the light emitting region of the infrared LED is matched to the entire region of the image as shown in FIG.

For this purpose, for example, a light control control lens 300 is further provided on the front surface of the infrared LED array 202, and the range of the light transmitting area of the infrared LED can be adjusted by adjusting the focus of the light transmission control lens 300 .

The focus control of the light emission control lens 300 can be performed by a known varifocal lens structure, FIG. 12 illustrates a manual adjustment method using the lens position shift lever 400, FIG. 13 illustrates a lens position An automatic adjustment method using the moving drive motor 500 will be described. Such a manual or automatic focal length lens structure allows the size of the light emitting region of the infrared LED to be adjusted to the size of the image captured by the camera.

As another example, a view angle adjusting means of an infrared LED may be further provided on the front surface of the infrared LED array, and the range of the light transmitting region of the infrared LED may be adjusted by the view angle adjusting means.

The view angle adjusting means may be, for example, a well-known infrared LED fixing means, and may be manufactured by changing the shape angle of the infrared ray fixing portion according to the view angle of the required infrared ray LED, or by changing the angle of the infrared ray fixing portion In the case of a possible structure).

As shown in FIG. 15, since the infrared LED is not disposed at the center of the bullet-type camera, the infrared LED disposed at the center portion covers the center portion of the image captured by the camera. Or an infrared LED may be installed so that the edge portion and the view angle are different from each other.

In matching the range of the image as described above with the range of the transmissive area of the infrared LED, an area in which one infrared LED is projected onto the subject must be appropriately designed in accordance with the specification of the infrared LED. For example, in consideration of the factors related to the view angle of the infrared LED, the information about the camera lens, the size of the image sensor (image pickup device), the resolution of the image sensor, Should be set. For example, when a CCD sensor is used, the angle of view of the image sensor can be obtained by the following Equation (2). However, in calculating the expression (2), the angle of view of the lens is calculated and the projection angle of the infrared LED array (light projector) is calculated. At this time, it is assumed that there is no light attenuation according to the distance of the infrared LED array (light emitter).

Table 1 below illustrates the type and size of a typical image sensor.

Image Sensor Type One" 2/3 " 1/2 " 1/3 " 1/4 " Landscape Image Sensor 12.8 mm 8.8 mm 6.4mm 4.8mm 3.6mm Image Sensor Vertical 9.6 mm 6.6mm 4.8mm 3.6mm 2.7mm

200: camera 202: infrared LED array
206: Infrared LED control unit 208: Video signal processing unit
210:

Claims (5)

An infrared LED array in which a plurality of infrared LEDs are arranged and arranged so as to face the photographing direction of the camera, an image pickup device unit for converting the image inputted through the camera lens into an electric signal, And an infrared LED control unit for controlling a light output of the infrared LED array based on the digital image data output from the image signal processing unit, As an infrared LED camera system,
Wherein the infrared LED control unit comprises:
While maintaining the total light output power of the infrared LED array high within a range in which the image is not saturated, the area of the entire region of the image, which is determined to have brightness lower than a predetermined reference value, So that the light output of the infrared LED is set higher,
The entire area of the image is divided into a plurality of unit areas, a control area composed of at least one unit area is set, and the light output of the infrared LED corresponding to each control area is individually controlled based on the brightness of each control area Respectively,
A first average value for brightness of a plurality of unit areas included in each control area is calculated and a light output of an infrared LED corresponding to the control area is individually controlled based on the first average value,
A first average value of each control area included in the reference image frame and a predetermined number of consecutive frames temporally preceded by the reference image frame, respectively, based on an image frame corresponding to a light emission output control time point of the infrared LED array, Wherein the control unit is configured to calculate a second average value for the first average values of the same control areas and independently control the light output of the infrared LED corresponding to the control area based on the second average value.
delete delete delete The method according to claim 1,
Wherein the range of the light transmitting region of the infrared LED is adjustable by adjusting the focus of the light projecting control lens provided on the front surface of the infrared LED array or adjusting the view angle of the infrared LED array.

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