KR101372068B1 - Method of testing illumination apparatus using light emitting diode for target spectrum - Google Patents

Abstract

Disclosed is a method for testing performance of an illumination apparatus using light emitting diodes as a light source. The method comprises the steps of: setting a target spectrum which is close to blackbody radiation light or daylight, or shows the distribution of a specific spectrum identical to the spectrum of a standard light source; drawing a comparison spectrum acquired by measuring manufactured illumination apparatus; commonizing two spectrums into conversion spectrums by using a commonization coefficient so that the units and scales of the two conversion spectrums are synchronized; integrating and comparing the two conversion spectrums with each other through a specific section; and calculating the comparison result to draw a synchronization rate and comparing the drawn result with a reference synchronization rate. [Reference numerals] (AA) Start; (BB) End; (S100) Set a target spectrum; (S110) Set a comparison spectrum; (S120) Perform communization; (S130) Draw a synchronization rate through the calculation of a difference value; (S140) Compare the synchronization rate with a reference synchronization rate

Description

Method of Testing Illumination Apparatus using Light Emitting Diode for Target Spectrum}

The present invention relates to a performance test of a lighting apparatus using a light emitting diode, and more particularly, to a performance test of a lighting apparatus using a light emitting diode measuring the degree to which the spectrum of the light emitting diode is matched with a target spectrum and indicating this as a performance index. will be.

A light emitting diode is a device that performs a light emitting operation by recombination of electrons and holes. An n-type semiconductor layer for supplying electrons and a p-type semiconductor layer for supplying holes are provided in the light emitting diode to perform the light emission operation. In addition, a multi-quantum well structure is employed in the active layer where recombination of electrons and holes is performed to induce a quantum confinement effect. Therefore, the wavelength of light generated in the light emitting diode is characterized by the band gap energy of the barrier layer in the quantum well structure.

In addition, a fluorescent material is coated on the light emitting diode during the packaging process. The fluorescent material performs an operation of converting light of an incident short wavelength band into a long wavelength band. Thus, the light emitting diode can form white light having various spectra.

When implementing a lighting device using a light emitting diode, the light formed from the lighting device should be close to the white light. In particular, illumination is evaluated to have excellent quality as natural light approaches closer to the sunlight or the black body radiation. Therefore, the spectrum of the lighting device implemented using the light emitting diode needs to be similar to the spectrum of the single-day sunlight or the blackbody radiation.

Accordingly, the International Commission on Illumination has set the standard light source as a standard of light spectrum, and it is also defined as an industrial standard in Korea. For example, standard light sources include A, B, C, D, F, and the like, and these standards are subdivided, modified, and supplemented with the development of lighting technology. For example, in the case of the D light source, it supplements the C light source representing the average daylight in the clear sky, and is a standard in which the color temperature is arbitrarily adjusted. Typically, D65 is typical, D stands for daylight, and the number 65 stands for 6500K associated color temperature.

Testing how close the manufactured light source is to a standard light source generally measures the difference in the intensity of light at a particular wavelength. Therefore, the intensity of the standard set as the standard light source and the intensity of the actually measured light source are compared and analyzed at a specific wavelength to evaluate whether the standard light source is close to the standard light source.

The test method of the above-described light source contains various errors. For example, in the case where only the intensity at a specific wavelength is measured and compared, there is a disadvantage in that the overall intensity at other wavelengths implementing white light cannot be measured. In addition, there is a lack of logical correlation that such light coincides with the entire spectrum of the standard light source as a target even if the intensity at a specific wavelength matches. To compensate for this, intensities at a plurality of wavelengths are measured, and a plurality of intensities are compared with intensities of standard light sources. However, this method also has a disadvantage in that it is limited to the measurement of the typical wavelength band of the white light. Therefore, there is no accurate evaluation of how close the illumination device using the manufactured light emitting diode is to the standard light source as the target light source.

An object of the present invention is to provide a method for testing a lighting device by measuring the similarity to the target spectrum in the lighting device using a light emitting diode.

The present invention for achieving the above object, setting a target spectrum as a reference for the lighting device; Setting a comparison spectrum by measuring light intensity according to a wavelength of the illumination device; Setting commonization coefficients for each of the target spectrum and the comparison spectrum to perform a common operation of units and scales; And performing a comparison operation of the conversion target spectrum and the conversion comparison spectrum derived through the commonization operation to derive a coincidence ratio.

According to the present invention described above, the target spectrum and the comparison spectrum having different units and characteristic curves are matched to each other and the scale is matched using a commonization coefficient. Therefore, the measurement error which appears only by measuring the difference in the intensity of light at a specific wavelength is eliminated. In addition, the comparison of the conversion spectra is performed through the comparison of the integral value in a specific wavelength range. Therefore, the trend of the spectrum and the difference with the target spectrum in the interval of the wavelength of interest can be accurately compared, thereby determining whether or not the comparison spectrum follows the target spectrum.

According to the present invention described above, the lighting device manufactured using the light emitting diode can be accurately calculated through the derivation of the coincidence rate Ccord. Therefore, whether the fabricated lighting apparatus follows the target light source in the desired wavelength band can be accurately tested.

1 is a flowchart for performing a performance test through comparison with a target spectrum of a lighting device employing a light emitting diode according to a preferred embodiment of the present invention.
2 to 4 are graphs illustrating the flow chart of FIG. 1 according to a wavelength band according to a preferred embodiment of the present invention.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

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.

Example

1 is a flowchart for performing a performance test through comparison with a target spectrum of a lighting device employing a light emitting diode according to a preferred embodiment of the present invention.

Referring to FIG. 1, first, a target spectrum is set (S100).

The target spectrum is preferably a standard light source A, D65 and the like prescribed by the International Lighting Commission. For example, the target spectrum may be set to D65. The interval of the wavelength in the set target spectrum is about 5nm, the interval of the wavelength is 300nm to 830nm. The wavelength section is preferably set within a wavelength band having meaning as white light. If the lower limit is set to a value of less than 300 nm, the wavelength is included in the target spectrum until the wavelength band does not contribute to white light. In addition, when the upper limit is set to a value exceeding 830 nm, an excessive long wavelength of light may be set as a target spectrum to cause an error in performance test. Table 1 below extracts a part of standard light source D65 as a target spectrum.

λ, nm Standard Illuminant D65 380 49.975500 385 52.311800 390 54.648200 395 68.701500 400 82.754900 405 87.120400 410 91.486000 415 92.458900 420 93.431800 425 90.057000 430 86.682300 435 95.773600 440 104.865000 445 110.936000 450 117.008000

Therefore, the intensity according to the wavelength in the target spectrum is represented by f (λ). For example, f 380 becomes 49.9755.

Referring back to FIG. 1, a comparison spectrum is set (S110). The comparison spectrum is set to the measured value of the illuminating device of the manufactured light emitting diode. That is, the intensity of light measured for each wavelength is set as a comparison spectrum. For example, the comparison spectrum can be set in Table 2 below. The measurement range of the comparison spectrum is the same as the range of the wavelength set in the target spectrum. Thus, the comparison spectrum is measured in the wavelength range of 300 nm to 830 nm.

λ, nm Specimen (W / nm) 380 0.000002 385 0.000005 390 0.000013 395 0.000033 400 0.000066 405 0.000079 410 0.000057 415 0.000039 420 0.000031 425 0.000028 430 0.000036 435 0.000058 440 0.000106 445 0.000173 450 0.000243

Therefore, the intensity according to the wavelength of the measured comparative spectrum is represented by g (λ). For example, g 300 is 0.000002.

Referring back to FIG. 1, unitization of both spectra is performed by setting a commonization coefficient (S120). For example, the commonization coefficient a of the target spectrum f (λ) and the commonization coefficient b of the comparison spectrum g (λ) are set. In addition, the determination of the commonization coefficients is set at the intermediate value of the wavelength band to be measured and compared. For example, when it is desired to select common and coefficients from 300 nm to 830 nm, the intermediate wavelength value is first determined. Therefore, the intermediate wavelength is 565 nm.

Therefore, the set commonization coefficient is expressed by the following equations (1) and (2).

In Equations 1 and 2, Mapp means an approximation of the target spectral maximum. In addition, λc means an intermediate wavelength value of the wavelength range of the target spectrum.

For example, Mapp is set to an approximation of the maximum value of the target spectrum. Therefore, it is preferably set to 80% to 120% of the maximum value. If the approximation of the maximum value is less than 80% of the maximum value, the target spectrum itself may be scaled down as a whole, thereby causing a problem in that it does not reflect the change in minute intensity for each wavelength band. In addition, when Mapp exceeds 120% of the maximum value, the change in size in the target spectrum is excessively enlarged, which increases the possibility of error in subsequent calculations.

Therefore, based on Table 1, the approximate value Mapp of the maximum value of the target spectrum may be set to 100.

The commonization is performed using the commonization coefficients derived according to Equations 1 and 2 described above. Performing the commonization results from derivation of the transform spectra using the commonization coefficient. For example, the conversion target spectrum is represented by af (λ), and the conversion comparison spectrum is represented by bg (λ).

Referring to FIG. 1, a difference value between a transform target spectrum and a transform comparison spectrum is calculated using a commonization coefficient (S130).

The calculation of the difference value is performed through the integration of the difference values of the two converted spectra in which the units are matched in the range of the specified wavelength band λstt to λstop and the ratio of the spectral curve is matched. The difference value is calculated according to Equation 3 below.

In addition, the coincidence rate Ccord for the standard spectrum using the difference value Ddiff derived from Equation 3 is as shown in Equation 4 below.

는 측정되는 파장대역 λstt 내지 λend 범위에서의 변환 목표 스펙트럼의 적분치를 나타낸다. 또한,

는 변환 목표 스펙트럼과 변환 비교 스펙트럼의 차이값의 적분치를 나타낸다. 따라서, 상기 일치율 Ccord는 변환 목표 스펙트럼에 대한 변환 비교 스펙트럼의 일치율을 나타낸다.In Equation (4)

Denotes the integral value of the conversion target spectrum in the wavelength band lambda stt to lambda end measured. Also,

Denotes the integral of the difference between the conversion target spectrum and the conversion comparison spectrum. Thus, the coincidence rate Ccord represents the coincidence rate of the transform comparison spectrum with respect to the transform target spectrum.

Subsequently, referring to FIG. 1, it is determined whether the comparison spectrum matches the target spectrum (S140). For this purpose, the reference coincidence rate Cstd for determining the measured coincidence rate Ccord is set. The reference matching ratio is a value that can be set differently according to the user of the lighting apparatus in which the light emitting diode is used. Therefore, when the match rate Ccord is determined to be equal to or greater than the reference match rate Cstd, the manufactured lighting device is determined to be good.

2 to 4 are graphs illustrating the flow chart of FIG. 1 according to a wavelength band according to a preferred embodiment of the present invention.

Referring to Fig. 2, a comparison spectrum of the set target spectrum and the measured light is shown. The target spectrum is indicated by a dotted line and the comparative spectrum is indicated by a solid line. In particular, the target spectrum does not appear in units according to the criteria of the International Lighting Organization. In addition, the target spectrum shown in FIG. 2 represents D65. The measured comparative spectrum shows the intensity of the light measured from the fabricated illuminator and the unit is W / nm. Thus, both curves differ in units and no agreement in magnitude appears.

Referring to FIG. 3, the unit of the comparison spectrum is removed through conversion and converted into converted spectra. For this purpose, the center wavelength of the two spectra is determined, the commonization coefficients a and b are determined, and the transform spectra are calculated. The two transformed spectra by the transform spectrum are transformed to have similar sized ranges. That is, the conversion target spectrum is converted to af (λ), and the conversion comparison spectrum is converted to bg (λ).

Referring to FIG. 4, λstt and λstop, which are upper and lower wavelength ranges for similarity measurement, are determined for two transformed spectra through commonization, and a comparison operation is performed on the transformed target spectrum and the transformed comparison spectrum. This allows us to compute the coincidence rate Ccord. Thereafter, the calculated match rate Ccord may be used to determine how much the measured lighting apparatus follows the target spectrum by comparing with the preset reference match rate Cstd. Through this, it is possible to determine the degree to which the lighting device manufactured using the light emitting diode matches the natural light or the target light source, and compare the characteristics in the wavelength band to be measured.

In the above-described present invention, the unity and the unity of scales are performed by using a commonization coefficient between a target spectrum and a comparison spectrum having different units and characteristic curves. Therefore, the measurement error which appears only by measuring the difference in the intensity of light at a specific wavelength is eliminated. In addition, the comparison of the conversion spectra is performed through the comparison of the integral value in a specific wavelength range. Therefore, the trend of the spectrum and the difference with the target spectrum in the interval of the wavelength of interest can be accurately compared, and thus it is determined whether the comparison spectrum follows the target spectrum.

According to the present invention described above, the lighting device manufactured using the light emitting diode can be accurately calculated through the derivation of the coincidence rate Ccord. Therefore, whether the fabricated lighting apparatus follows the target light source in the desired wavelength band can be accurately tested.

Claims (7)

Setting a target spectrum as a reference for the lighting device;
Setting a comparison spectrum by measuring light intensity according to a wavelength of the illumination device;
Setting commonization coefficients for each of the target spectrum and the comparison spectrum to perform a common operation of units and scales; And
And performing a comparison operation of the conversion target spectrum and the conversion comparison spectrum derived through the commonization operation to derive a matching rate. The method of claim 1, wherein performing the commoning operation comprises:
Setting the commonization coefficient and the comparison spectrum of the target spectrum with the commonization coefficient; And
And deriving a conversion target spectrum using the commonization coefficient of the target spectrum and deriving a conversion comparison spectrum using the commonization coefficient of the comparison spectrum. The method of claim 1, wherein after deriving the coincidence rate,
And determining whether or not the lighting device is good by comparing a predetermined reference matching rate with the derived matching rate. The method of claim 1, wherein the target spectrum is a standard light source A or D65. The method of claim 1, wherein the commonization coefficients are represented by Equation 1 and Equation 2 below.
[Equation 1]

&Quot; (2) "

a is a commonization coefficient of the target spectrum, b is a commonization coefficient of the comparison spectrum, and Mapp is an approximation of the target spectrum maximum. f (λc) is the intensity at the middle wavelength of the target spectrum, and g (λc) is the intensity at the middle wavelength of the comparison spectrum. The method according to claim 5, wherein the conversion target spectrum is af (λ), and the conversion comparison spectrum is bg (λ). The method of claim 6, wherein the matching ratio is derived according to Equation 3 and Equation 4 below.
&Quot; (3) "

&Quot; (4) "

Diff is the difference value, Ccord is the coincidence rate, λstt is the operation start wavelength of the integral operation, and λstop is the operation end wavelength of the integration operation.

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