KR20110101688A - Analysis method of led beam degradation characteristics and apparatus for the same - Google Patents

Abstract

A method and apparatus for analyzing an LED beam emission pattern before and after high dose gamma ray irradiation using a color CCD image are disclosed. In the beam degradation characteristic analysis method of the LED according to the present invention, the method comprises: irradiating a high-dose gamma ray to the LED, obtaining a beam pattern of the LED to which the obtained high-dose gamma ray is irradiated, and analyzing the obtained beam pattern of the LED It includes a step. According to such a configuration, it is possible to know the effect of irradiation of high-dose gamma rays for each type of LED, and ultimately, the extent to which the visible light wireless communication system can be applied to the sensor / communication network inside the reactor bundle.

Description

ANALYSIS METHOD OF LED BEAM DEGRADATION CHARACTERISTICS AND APPARATUS FOR THE SAME

The present invention relates to a method and an apparatus for analyzing beam degradation characteristics of LEDs, and more particularly, to analyze LED beam emission patterns before and after high-dose gamma-ray irradiation using color CCD images and projection profiling analysis. A method and apparatus therefor.

The sensor / communication system inside the in-containment building is wired. A review is underway to establish this as a wireless sensor / communication network system.In the preventive maintenance period with the reactor stopped, the sensor data is used to evaluate the health of the main equipment inside the reactor building during the preventive maintenance period with the reactor stopped. Cases of testing a wireless data transmission system for transmitting and receiving wirelessly have been reported.

However, there have been no reports of the application of wireless sensors / communication systems inside the reactor building during commercial operation to generate power by operating nuclear reactors, which is related to the safety of nuclear power plants by EMI and RFI caused by electromagnetic waves emitted from radio terminals. This can lead to malfunction of key equipment, systems and equipment.

For this reason, in order for a wireless communication system to be adopted in major equipment, systems, and facilities of a nuclear power plant safety system, it is necessary to prevent malfunctions as much as possible. In order not to cause malfunctions, the electric field strength of the wireless terminal must be weak and the straightness must be excellent.

On the other hand, since visible light is an optical wave, there is no interference between electromagnetic waves and high frequencies, and the wavelength is shorter than that of electromagnetic waves, so the light-of-sight (LOS) is excellent. Therefore, it is possible to build a communication line that does not directly affect the safety system equipment inside the reactor building using the visible light wireless communication system. However, in order to apply the visible light communication system to the sensors / telecommunication networks inside the reactor building, the visible light communication system must be verified for viability in a high dose gamma ray exposure environment having a design basis accident (DBA) requirement.

The present invention has been made in view of the above problems, and after irradiating high-dose gamma rays to the LED which is a key element of visible light wireless communication, the beam deterioration characteristics of the LED can be seen how it affects the beam characteristics of the LED An object of the present invention is to provide an analysis method and a device thereof.

Another object of the present invention is to provide a beam degradation characteristic analysis method and apparatus for analyzing LED light emission patterns before and after irradiation with high dose gamma rays using a CCD camera and a simple image processing algorithm.

Beam deterioration characteristic analysis method of the LED according to an embodiment of the present invention for achieving the above object comprises the steps of irradiating a high dose gamma ray to the LED, obtaining a beam pattern of the LED irradiated with the high dose gamma ray, And analyzing the beam pattern of the obtained LED.

The acquiring of the beam pattern of the LED may include supplying a DC current to the LED irradiated with high-dose gamma rays in an LED driving circuit, forming a pattern of a beam emitted from the LED on the imaging plate, and Obtaining a pattern of the beam as a CCD image. At this time, the step of acquiring the pattern of the beam as a CCD image is performed in a dark environment.

On the other hand, analyzing the beam pattern of the LED, separating the obtained beam pattern of the LED into RGB (Red, Green, Blue) components, obtaining the beam pattern characteristics of the LED through the RGB component, And comparing and analyzing the beam pattern characteristics of the LED and the beam pattern characteristics of the LED to which the high dose gamma ray is not irradiated.

In this case, the step of obtaining the beam pattern characteristics of the LED further comprises the step of performing a projection profiling process for each of the RGB components. And modeling a beam pattern of the LED through the projection profiling process as a Gaussian function.

In addition, comparing and analyzing the beam pattern characteristics may include comparing beam intensity and diffusion angle of an LED to which high dose gamma rays are irradiated and an LED not exposed to high dose gamma rays using the modeled Gaussian function. .

An apparatus for analyzing beam degradation characteristics of an LED according to an embodiment of the present invention, which provides the above analysis method, includes: an LED receiving current from an LED driving circuit; an imaging plate on which a pattern of beams generated from the LED is formed; And a CCD camera unit for acquiring a beam pattern of the LED formed on the plate as a CCD image, and a controller for analyzing beam pattern information of the LED obtained from the CCD camera unit.

In this case, the controller performs the operation of obtaining the LED beam pattern characteristics by separating the obtained beam pattern of the LED into RGB components. The controller may perform projection profiling on the RGB components of the beam pattern of the LED to analyze beam pattern information of the LED. The control unit models a beam pattern of the LED through the projection profiling process as a Gaussian function and derives a Gaussian function through data fitting.

According to the present invention having the configuration as described above, first, it can be seen how the high-dose gamma rays affect the beam characteristics of the LEDs, and in particular, the effects on the various kinds of LEDs, ultimately visible light wireless Find out how applicable the communication scheme is to the sensors / communications inside the reactor building.

Second, it is possible to analyze the beam characteristics of the LEDs through image processing technology using a CCD camera, so that the beam degradation characteristics of the LEDs can be determined numerically according to the type of LEDs. It can be determined whether it can be employed in the visible light wireless communication system applied to.

1 is a configuration diagram schematically showing an apparatus for analyzing beam degradation characteristics of an LED according to an embodiment of the present invention;
2 is a flowchart illustrating a method of analyzing beam degradation characteristics of an LED according to an embodiment of the present invention;
3A and 3B are graphs of a projection profiling process for RGB components of an LED beam pattern, and
4 is a graph of applying a Gaussian model by taking only the green wavelength component of FIGS. 3A and 3B.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As mentioned earlier, since visible light is an optical wave, there is no electromagnetic and high frequency interference, and the wavelength is short, so the straightness is excellent. Thus, a communication line without directly affecting the safety system equipment inside the reactor building can be constructed. However, in order to apply the visible light communication system to the sensors / telecommunication networks inside the reactor building, the visible light communication system must be verified for viability in a high dose gamma ray exposure environment having a design basis accident (DBA) requirement. On the other hand, LED is a core element of visible light wireless communication, the beam degradation characteristic analysis device (1) of the LED according to the present invention is used to analyze the beam degradation characteristics of the LED irradiated with high-dose gamma rays, the high-dose gamma rays obtained through From the beam deterioration characteristics of the irradiated LED, it is possible to judge the applicability to the inside of the reactor building of visible light wireless communication.

The beam degradation characteristic analysis apparatus 1 of the LED includes an LED 10, an imaging plate 20, a CCD camera unit 30, and a controller 40. 1 is shown for more detailed description. 1 is a configuration diagram schematically showing an apparatus 1 for analyzing beam degradation characteristics of an LED according to an embodiment of the present invention.

LED 10 is a key element of visible light wireless communication, preferably a high-brightness LED is used. As the LED 10 employed in the beam deterioration characteristic analysis device 1 of the LED according to the present invention, an LED irradiated with a high dose gamma ray and an LED not exposed to the high dose gamma ray are used. In particular, high-dose gamma-irradiated LEDs are irradiated with high-dose gamma rays for 72 hours at a dose rate of 4 kGy / h that corresponds to the design criteria for RTD (resistance temperature detector) sensors for measuring the coolant temperature of the reactor coolant system. It is illustrated as being done. That is, the LED 10 irradiated with high dose gamma rays is irradiated with gamma rays of 288 kGy or more based on a cumulative exposure dose (TID, total irradiation dose).

As a result of the experiment, the LED 10 irradiated with high dose of gamma ray is colored brown. Therefore, by using the beam degradation characteristic analysis device 1 of the LED according to the present invention it can be seen how the coloration of the LED affects the beam characteristics of the LED.

The LED 10 receives a DC current from the LED driving circuit 11 and emits light. At this time, the DC current is preferably supplied in the range of 40 ~ 60mA. When the LED 10 emits light, the LED beam is irradiated onto the imaging plate 20 spaced apart from the LED 10. That is, the pattern of the LED beam is formed on the imaging plate 20. The imaging plate 20 is exemplified by glass, but is not limited thereto.

The CCD camera unit 30 is positioned to face the LED 10, and the imaging plate 20 is positioned between the CCD camera unit 30 and the LED 10. Therefore, the CCD camera unit 30 acquires the beam pattern of the LED 10 formed on the imaging plate 20 as a CCD image.

The controller 40 analyzes this by using the CCD image of the beam pattern of the LED 10 thus obtained. The analysis method of the control unit 40 will be described in detail together with the beam degradation characteristic analysis method of the LED according to an embodiment of the present invention. 2 is shown for more detailed description. 2 is a flowchart illustrating a method of analyzing beam degradation characteristics of an LED according to an embodiment of the present invention.

Method for analyzing the beam degradation characteristics of the LED according to the present invention comprises the steps of irradiating a high dose gamma ray to the LED 10 (S10), obtaining a beam pattern of the LED 10 irradiated with the high dose gamma ray (S20), And the step (S30) of analyzing the obtained beam pattern of the LED (10).

First, the method for analyzing the beam degradation characteristics of the LED is to determine whether the LED 10, which is a core element of visible light wireless communication, is viable in a high dose gamma ray exposure environment. Dose gamma radiation is irradiated (S10). In this case, the high-dose gamma ray is exemplified as irradiating more than 288 kGy based on the cumulative exposure dose (TID) as described above.

When the target LED 10 is prepared in this way, the beam pattern of the LED 10 irradiated with the high-dose gamma ray is obtained (S20). The beam pattern obtaining step includes the current supplying step (S21) to the LED 10, the LED. The beam pattern forming step (S22) of (10), and the CCD image acquisition step (S23) of the LED 10 beam pattern.

First, a DC current is supplied from the LED driving circuit 11 to the LED 10 irradiated with the high dose gamma ray (S21). At this time, the DC current is preferably supplied at 40 ~ 60mA as described above. The LED 10 emits light by supplying current, and the LED beam forms a pattern on the imaging plate 20 exemplified by glazing (S22). When the beam pattern of the LED 10 is formed on the imaging plate 20, the camera unit 30 obtains a CCD image (S23).

Meanwhile, the obtaining of the beam pattern of the LED 10 as a CCD image is preferably performed in a dark room environment. This is to reduce the influence of background lighting as much as possible while acquiring the CCD image.

When the beam pattern of the target LED 10 is obtained as a CCD image, the controller 40 analyzes the obtained beam pattern of the LED 10.

The analyzing of the beam pattern (S30) may include separating RGB components of the LED 10 beam pattern (S31), projecting profiling process (S32), Gaussian function deriving step (S33), and the LED 10 beam pattern. Characteristic comparison analysis step (S34) is included.

First, the beam pattern of the obtained LED 10 is separated into RGB (Red, Green, Blue) components (S31). In this case, in order to compare the beam degradation characteristics of the LEDs exposed to the high dose gamma rays and the beam degradation characteristics of the LEDs not exposed to the high dose gamma rays, the beam pattern for the LEDs not exposed to the high dose gamma rays is also obtained and converted into RGB components. It is preferable to separate.

After the beam pattern of the LED 10 is separated into RGB components, projection profiling is performed on each RGB image (S32). Through this projection profiling process, the intensity distribution curve of the LED 10 beam can be obtained. This projection profiling technique is to integrate the intensity of the LED 10 beam in the X-axis or Y-axis direction by the following equations (1) and (2).

By using the above method, it is possible to obtain the intensity distribution of the LED 10 beam that is robust to noise and local changes. The intensity distribution of the LED 10 beam through the projection profiling process is illustrated in FIGS. 3A and 3B. 3A is a graph of LED 10 not exposed to high dose gamma rays, and FIG. 3B is a graph of LED 10 irradiated with high dose gamma rays. In both graphs, the Y axis represents the intensity of the beam arbitrarily, and the X axis represents the X axis of image coordinates. At this time, the LED 10 used a high brightness green LED.

Meanwhile, as shown in FIGS. 3A and 3B, the intensity distribution of the LED 10 beam obtained by the projection profiling technique shows a Gaussian distribution. Accordingly, the beam pattern (intensity distribution) of the LED 10 through the projection profiling process is modeled as a Gaussian function by using Equation 3 below, and a Gaussian function is derived through data fitting (S33). ).

Where A is amplitude and w is width. A graph comparing the derived Gaussian model to the LED 10 irradiated with high dose gamma rays and not exposed to the high dose gamma rays is illustrated in FIG. 4. In this case, the Y axis represents a normalized beam intensity, and the X axis represents an X axis of image coordinates. 4 is a Gaussian model obtained by taking only the green wavelength component from the distribution curves of FIGS. 3A and 3B. After applying the Gaussian model to the LED 10 before and after irradiation with high dose gamma rays, an initial value of the DC component y is obtained. The components are shown by removing each.

When the Gaussian function is derived, the beam intensity and the diffusion angle of the LED 10 irradiated with the high dose gamma ray and the LED 10 not exposed to the high dose gamma ray are compared (S34). Through this comparison, it is possible to compare and analyze the beam pattern characteristics of the LED 10 according to the irradiation of high-dose gamma rays.

For example, according to the information obtained from the illustration of FIG. 4, the maximum amplitude of the LED beam is reduced by about 11% and the beam spread angle (w / A) is reduced due to the coloring of the LED 10 by irradiation of high dose gamma rays. It can be seen that about 5.5% increase. On the other hand, if it is assumed that the data transmission distance between the LED 10 and the light receiving element PD is constant, it means that the amount of light incident on the LED 10 beam to the effective cross-sectional area of the light receiving element decreases when the beam width increases. As can be seen, the above results indicate that irradiation of high dose gamma rays degrades the performance of the LED 10.

In the above embodiment, the experiment was performed by exemplifying only the green high-brightness LED 10, and the beam deterioration characteristics of the LED 10 may be analyzed by applying to various LEDs 10 such as red, blue, yellow, and white. For example, if the comparison target for the characteristic change of the LED 10 according to the irradiation of high-dose gamma rays is the beam intensity deviation I (var) and the beam spread angle deviation Φ (var), Equation 4 And deterioration of beam characteristics of the LEDs 10 in various wavelength bands by using Equation 5.

For reference, beam characteristic degradation of LEDs 10 in various wavelength bands is shown in Table 1 below.

Table 1 shows the beam intensity deviation I (var) and the beam spreading angle deviation Φ (var) with respect to the LEDs 10 in each wavelength band. Therefore, through the beam degradation characteristics analysis method of the LED according to an embodiment of the present invention, it is possible to determine the effect of high-dose gamma rays on the various types of LED (10). As a result, referring to Table 1, if the visible light wireless communication system is applied to the inside of the reactor building, the result is that it is efficient to use the LED 10 of the red wavelength band as a light source. However, this only considers the LED 10 element, and it is assumed that the light receiving element PD and the driving circuits for constructing the visible light wireless communication system are robust in the high dose gamma ray irradiation environment of the design standard accident requirement.

The method of analyzing beam degradation characteristics of an LED according to an embodiment of the present invention as described above may be utilized for designing a transmitter of a visible light wireless data transmission system in a high radiation area inside a nuclear power plant containment building using LED beam intensity degradation characteristics. Can be.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1: LED beam degradation characteristic analysis device 10: LED
11: LED drive circuit 20: imaging plate
30: camera unit 40: control unit

Claims (11)

Irradiating high dose gamma rays to the LEDs;
Obtaining a beam pattern of the LED to which the high dose gamma ray is irradiated; And
Analyzing a beam pattern of the obtained LED;
Beam degradation characteristics analysis method of the LED comprising a. The method of claim 1,
Acquiring the beam pattern of the LED,
Supplying a DC current to the LED irradiated with high dose gamma rays in an LED driving circuit;
Forming a pattern of a beam emitted from the LED on the imaging plate; And
Acquiring a pattern of the beam as a CCD image;
Beam degradation characteristics analysis method of the LED comprising a. The method of claim 2,
The method of analyzing the beam degradation characteristics of the LED, characterized in that the step of acquiring the pattern of the beam as a CCD image in a dark room environment. The method according to claim 1 or 3,
Analyzing the beam pattern of the LED,
Separating the obtained beam pattern of the LED into RGB (Red, Green, Blue) components;
Obtaining beam pattern characteristics of the LEDs through the RGB components; And
Comparing and analyzing the beam pattern characteristics of the LED and the beam pattern characteristics of the LED to which the high dose gamma ray is not irradiated;
Beam degradation characteristics analysis method of the LED comprising a. The method of claim 4, wherein
Obtaining the beam pattern characteristics of the LED,
And a projection profiling process for each of the RGB components. The method of claim 5,
And modeling a beam pattern of the LED through the projection profiling process as a Gaussian function and deriving a Gaussian function through data fitting. The method of claim 6,
Comparing and analyzing the beam pattern characteristics,
And comparing the beam intensity and the diffusion angle of the LED irradiated with the high dose gamma ray and the LED not exposed to the high dose gamma ray using the modeled Gaussian function. LED receiving current from the LED driving circuit;
An imaging plate on which a pattern of beams emitted from the LED is formed;
A CCD camera unit acquiring a beam pattern of the LED formed on the imaging plate as a CCD image; And
A controller which analyzes beam pattern information of the LED obtained from the CCD camera unit;
Beam degradation characteristic analysis apparatus of the LED comprising a. The method of claim 8,
The control unit is a beam degradation characteristic analysis device of the LED, characterized in that for performing the operation to obtain the beam pattern characteristics of the LED by separating the obtained beam pattern of the LED into RGB components. 10. The method of claim 9,
And the controller is configured to perform projection profiling on the RGB components of the beam pattern of the LED to analyze beam pattern information of the LED. The method of claim 10,
And the controller is configured to model the beam pattern of the LED through the projection profiling process as a Gaussian function and to derive a Gaussian function through data fitting.

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