CN104849025A - LED lamp on-line screening method based on brightness and color temperature test - Google Patents

Abstract

The invention relates to an LED color temperature detection and LED lamp quality detection method, and belongs to the technical field of LED detection. The method mainly comprises an LED lamp bead RGB tri-phosphor light intensity data acquisition and processing method, a method for calculating the LED lamp bead color temperature via the RGB tri-phosphor light intensity, and an LED lamp screening method according to the color temperature and the light intensity of each LED lamp bead of the LED lamp. The method for calculating the LED lamp bead color temperature via the RGB tri-phosphor light intensity comprises a method for calculating an XYZ tristimulus value via the RGB tri-phosphor light intensity, a method for calculating chromaticity coordinates via the XYZ tristimulus value, and a method for calculating the color temperature of the LED lamp beads via the chromaticity coordinates. The LED lamp screening method comprises determining the qualification condition of the LED lamps and choosing unqualified LED lamp beads of the unqualified LED lamps. Compared with the prior art, according to the method, the detection speed of the LED light source color temperature is fast, the qualification condition of the LED lamps can be determined, and the method is applicable to on-line detection of the LED lamps.

Description

A kind of online screening technique of LED lamp tested based on brightness and colour temperature

Technical field

The present invention relates to a kind of LED colour temperature to detect and LED lamp quality determining method, belong to LED detection technique field.

Background technology

The life-span is long, energy consumption is low, reliability is high, be easy to the features such as control because it has for LED light source, progressively replaces incandescent lamp and fluorescent lighting market, becomes lighting source of new generation.National governments are all vigorously supporting the development of white light LEDs, and many developed countries also set up special actively implementation by government.Along with the fast development of LED illumination technology in recent years, and the progressively expansion of its application, user has had higher quality to ask to LED illumination product, not only require that LED lamp ensures to some extent on the life-span, and require that the LED lamp bead of its inside has good consistance on luminosity and color.Thus just for LED detection technique proposes a difficult problem.

Nowadays, the instruments such as spectrometer, photometer, integrating sphere to be used for the brightness of LED and the test of colour temperature, although the advantage that these instruments have measuring accuracy high, it also has some shortcomings, such as: apparatus structure complexity, complicated operation, cost is high, test speed is slow.Therefore these instruments can only use in laboratory, are applied in above the experiment of some optic tests, cannot move towards production line.In order to can production line be moved towards, their features such as test speed just must be had fast, simple to operate.Therefore, in order to solve the consistency problem of LED lamp bead luminosity on production line in LED product and colour temperature, the present invention proposes a kind of online screening technique of LED lamp based on brightness and colour temperature test.

Summary of the invention

In view of the consistency problem of its lamp pearl brightness and colour temperature during LED lamp online production, the invention provides a kind of online screening technique of LED lamp tested based on brightness and colour temperature, to make up some vacancies of LED lamp online measuring technique on market.

A kind of online screening technique of LED lamp tested based on brightness and colour temperature provided by the invention, it comprises: the method for LED lamp bead RGB three primary colours light intensity data acquisition and processing, the method calculating LED lamp bead colour temperature by RGB three primary colours light intensity, the method for screening LED lamp according to colour temperature and the light intensity of each LED lamp bead in LED lamp.The described method calculating LED lamp bead colour temperature by RGB three primary colours light intensity comprises: by RGB three primary colours light intensity meter calculate XYZ tristimulus values method, to be calculated the method for chromaticity coordinates by XYZ tristimulus values, calculated the method for LED lamp bead colour temperature by chromaticity coordinates.Described LED lamp screening technique comprises: judge the Qualification of LED lamp and pick out underproof LED lamp bead in defective LED lamp.

A kind of online screening technique of LED lamp tested based on brightness and colour temperature provided by the invention, comprises following several step:

I) acquisition and processing is carried out to the luminous intensity data of LED lamp bead each in LED lamp;

II) luminous intensity is converted to XYZ tristimulus values;

III) chromaticity coordinates is calculated by XYZ tristimulus values;

IV) colour temperature of LED lamp bead is calculated by chromaticity coordinates;

V) according to the colour temperature of LED lamp bead each in LED lamp and light intensity, LED lamp is screened;

VI) underproof LED lamp bead is picked out according to the colour temperature of LED lamp bead each in LED lamp and light intensity.

Light intensity it is to be understood that involved in the present invention calculates and colour temperature result of calculation is not accurate calculates, and its result is just analyzed qualitatively to the light intensity of each LED lamp bead.

Accompanying drawing explanation

Fig. 1 is the online screening technique process flow diagram of LED lamp of the present invention

Fig. 2 is RGB three primary colours intensity collection system chart of the present invention

Fig. 3 be LED lamp of the present invention and lamp pearl thereof select process flow diagram

Embodiment

As shown in Figure 1, the present invention comprises altogether: carry out acquisition and processing to the luminous intensity data of LED lamp bead each in LED lamp, luminous intensity be converted to XYZ tristimulus values, calculated chromaticity coordinates by XYZ tristimulus values, calculated the colour temperature of LED lamp bead by chromaticity coordinates, according to the colour temperature of LED lamp bead each in LED lamp and light intensity is screened LED lamp, pick out underproof LED lamp bead 6 steps according to the colour temperature of LED lamp bead each in LED lamp and light intensity.

For the acquisition and processing of the luminous intensity data of LED lamp bead each in LED lamp, the present invention is divided into two aspects and carries out.Being the collection of data on the one hand, is the process of data on the other hand.As shown in Figure 2, for the collection of light intensity data, RGB three primary colours intensity collection system involved in the present invention forms primarily of 4 each several parts, is respectively optical filter, photoelectric conversion module, data selection passage, light intensity data acquisition module.Its principle of work is: when testing, the light that each LED lamp bead sends filters respectively through ruddiness optical filter, green glow optical filter and blue filter, carry out opto-electronic conversion (light intensity signal is converted to certain voltage signal) by the monochromatic light of photoelectric conversion module to red, green, blue three kinds of colors respectively after optical filtering, finally gathered by the voltage signal that data selection passage is corresponding to red, green, blue three kinds of light intensity respectively by intensity collection module.

Due in the driving power of driving LED light fixture containing high ordinary mail number or power frequency component, therefore need to carry out filtering process to the light intensity signal collected, its concrete disposal route is as follows:

I) by intensity collection module by data selection passage respectively to voltage signal continuous acquisition corresponding to red, green, blue three kinds of light intensity 10 times, institute's value is denoted as V respectively _r0, V _r1, V _r2, V _r3, V _r4, V _r5, V _r6, V _r7, V _r8, V _r9; V _g0, V _g1, V _g2, V _g3, V _g4, V _g5, V _g6, V _g7, V _g8, V _g9; V _b0, V _b1, V _b2, V _b3, V _b4, V _b5, V _b6, V _b7, V _b8, V _b9.

II) carry out mean filter to above-mentioned data to calculate:

${\stackrel{\‾}{V}}_r=(V_{r0}+V_{r1}+V_{r2}{+V}_{r3}+V_{r4}+V_{r5}+V_{r6}+V_{r7}+V_{r8}+V_{r9})/10$

${\stackrel{\‾}{V}}_g=(V_{g0}+V_{g1}+V_{g2}{+V}_{g3}+V_{g4}+V_{g5}+V_{g6}+V_{g7}+V_{g8}+V_{g9})/10$

${\stackrel{\‾}{V}}_b=(V_{b0}+V_{b1}+V_{b2}{+V}_{b3}+V_{b4}+V_{b5}+V_{b6}+V_{b7}+V_{b8}+V_{b9})/10$

In above three formulas represent the average of the data obtained after voltage signal continuous acquisition corresponding to red, green, blue three kinds of light intensity 10 times respectively.

III) can obtain according to step 1 and step 2, after mean filter, the voltage signal that on light fixture, red, green, blue three kinds of light intensity of the n-th lamp pearl are corresponding can be expressed as following form:

${\stackrel{\‾}{V}}_{r_n}=(V_{r_{n}0}+V_{r_{n}1}+V_{r_{n}2}+V_{r_{n}3}+V_{r_{n}4}+V_{r_{n}5}+V_{r_{n}6}+V_{r_{n}7}+V_{r_{n}8}+V_{r_{n}9})/10---\left(1\right)$

${\stackrel{\‾}{V}}_{g_n}=(V_{g_{n}0}+V_{g_{n}1}+V_{g_{n}2}+V_{g_{n}3}+V_{g_{n}4}+V_{g_{n}5}+V_{g_{n}6}+V_{g_{n}7}+V_{g_{n}8}+V_{g_{n}9})/10---\left(2\right)$

${\stackrel{\‾}{V}}_{b_n}=(V_{b_{n}0}+V_{b_{n}1}+V_{b_{n}2}+V_{b_{n}3}+V_{b_{n}4}+V_{b_{n}5}+V_{b_{n}6}+V_{b_{n}7}+V_{b_{n}8}+V_{b_{n}9})/10---\left(3\right)$

IV) power frequency filtering is carried out to the data after mean filter, it has step: first the voltage signal corresponding according to red, green, blue three kinds of light intensity of all lamp pearls in step 1 and step 2 pair light fixture carries out a mean filter, use the same method again after (1-10*nt) ms (t is converted to time needed for digital voltage signal for light intensity signal, and n is the number of lamp pearl on light fixture) and carry out 1 mean filter.So carry out 10 mean filters (half period of power frequency component is 10ms) altogether, its value is denoted as respectively: ${\stackrel{\‾}{V}}_{r_{n}0},{\stackrel{\‾}{V}}_{r_{n}1},{\stackrel{\‾}{V}}_{r_{n}2},{\stackrel{\‾}{V}}_{r_{n}3},{\stackrel{\‾}{V}}_{r_{n}4},{\stackrel{\‾}{V}}_{r_{n}5},{\stackrel{\‾}{V}}_{r_{n}6},{\stackrel{\‾}{V}}_{r_{n}7},{\stackrel{\‾}{V}}_{r_{n}8},{\stackrel{\‾}{V}}_{r_{n}9};{\stackrel{\‾}{V}}_{g_{n}0},{\stackrel{\‾}{V}}_{g_{n}1},{\stackrel{\‾}{V}}_{g_{n}2},{\stackrel{\‾}{V}}_{g_{n}3},{\stackrel{\‾}{V}}_{g_{n}4},{\stackrel{\‾}{V}}_{g_{n}5},{\stackrel{\‾}{V}}_{g_{n}6},{\stackrel{\‾}{V}}_{g_{n}7},{\stackrel{\‾}{V}}_{g_{n}8},{\stackrel{\‾}{V}}_{g_{n}9};$ ${\stackrel{\‾}{V}}_{b_{n}0},{\stackrel{\‾}{V}}_{b_{n}1},{\stackrel{\‾}{V}}_{b_{n}2},{\stackrel{\‾}{V}}_{b_{n}3},{\stackrel{\‾}{V}}_{b_{n}4},{\stackrel{\‾}{V}}_{b_{n}5},{\stackrel{\‾}{V}}_{b_{n}6},{\stackrel{\‾}{V}}_{b_{n}7},{\stackrel{\‾}{V}}_{b_{n}8},{\stackrel{\‾}{V}}_{b_{n}9}.$

V) carry out mean value computation again to the data obtained in step 4, the voltage signal that red, green, blue three kinds of light intensity of final n-th lamp pearl are corresponding can be expressed as:

$V_{r_n}=({\stackrel{\‾}{V}}_{r_{n}0}+{\stackrel{\‾}{V}}_{r_{n}1}+{\stackrel{\‾}{V}}_{r_{n}2}+{\stackrel{\‾}{V}}_{r_{n}3}+{\stackrel{\‾}{V}}_{r_{n}4}+{\stackrel{\‾}{V}}_{r_{n}5}+{\stackrel{\‾}{V}}_{r_{n}6}+{\stackrel{\‾}{V}}_{r_{n}7}+{\stackrel{\‾}{V}}_{r_{n}8}+{\stackrel{\‾}{V}}_{r_{n}9})/10---\left(4\right)$

$V_{g_n}=({\stackrel{\‾}{V}}_{g_{n}0}+{\stackrel{\‾}{V}}_{g_{n}1}+{\stackrel{\‾}{V}}_{g_{n}2}+{\stackrel{\‾}{V}}_{g_{n}3}+{\stackrel{\‾}{V}}_{g_{n}4}+{\stackrel{\‾}{V}}_{g_{n}5}+{\stackrel{\‾}{V}}_{g_{n}6}+{\stackrel{\‾}{V}}_{g_{n}7}+{\stackrel{\‾}{V}}_{g_{n}8}+{\stackrel{\‾}{V}}_{g_{n}9})/10---\left(5\right)$

$V_{b_n}=({\stackrel{\‾}{V}}_{b_{n}0}+{\stackrel{\‾}{V}}_{b_{n}1}+{\stackrel{\‾}{V}}_{b_{n}2}+{\stackrel{\‾}{V}}_{b_{n}3}+{\stackrel{\‾}{V}}_{b_{n}4}+{\stackrel{\‾}{V}}_{b_{n}5}+{\stackrel{\‾}{V}}_{b_{n}6}+{\stackrel{\‾}{V}}_{b_{n}7}+{\stackrel{\‾}{V}}_{b_{n}8}+{\stackrel{\‾}{V}}_{b_{n}9})/10---\left(6\right)$

VI) because when incident solid angles one timing, light intensity signal and voltage signal are linear within the scope of certain condition, therefore red, green, blue three kinds of light intensity of final n-th lamp pearl can be expressed as:

$I_{r_n}=k_r{V}_{r_n}+b_r---\left(7\right)$

$I_{g_n}=k_g{V}_{g_n}+b_g---\left(8\right)$

$I_{b_n}=k_b{V}_{b_n}+b_b---\left(9\right)$

Wherein k _r, k _g, k _b, b _r, b _r, b _rconversion coefficient between light intensity and voltage.

Again as shown in Figure 1, after the RGB three primary colours light intensity data of LED lamp bead each on light fixture draws, need to draw XYZ tristimulus values further.Change for rgb value and XYZ value, the conversion relational expression that the rgb value that the present invention uses CIE (International Commission on Illumination) to recommend is converted to XYZ value calculates, and its conversion relational expression is as follows:

$\left.\begin{array}{c}X=0.3568R+0.2889G+0.2132B\\ Y=0.1173R+0.9000G-0.0611B\\ Z=0.0095R-0.5294G+1.6196B\end{array}\right\}---\left(10\right)$

Wherein, the parameter R in the present invention in (10) formula, G, B respectively by replace.

Be converted to chromaticity coordinates for by XYZ value, the formula that the present invention uses CIE to recommend equally, its expression formula is as follows:

$\left.\begin{array}{c}x=\frac{X}{X+Y+Z}\\ y=\frac{Y}{X+Y+Z}\end{array}\right\}---\left(11\right)$

After drawing chromaticity coordinates, the colour temperature of lamp pearl can be drawn further.Because not high to the precise requirements of colour temperature in the present invention, therefore for the calculating of colour temperature, the present invention adopts approximate formula method to calculate, and its expression formula is as follows:

CCT＝499K ³+3525K ²+6823.3K+5520.33 (12)

Wherein K=(x-0.3320)/(0.1858-y), CCT represents colour temperature.

Again as shown in Figure 1, after LED lamp bead colour temperature meter calculates, screening LED lamp according to colour temperature and light intensity further and pick out underproof lamp pearl, as shown in Figure 3, its concrete steps are as follows:

I) colour temperature of lamp pearls all in LED lamp is numbered, is denoted as CCT respectively ₁, CCT ₂... CCT _n;

II) the one-dimension array C [n] (n equals the number of lamp pearl in LED lamp) that a length is n is defined;

III) by CCT ₁, CCT ₂... CCT _nascendingly to sort, after having sorted by ascending order stored in (final minimum color temperature value incorporates in C [0], and maximal value incorporates in C [n-1]) in array C [n];

IV) color temperature value in C [0] and C [n-1] is taken out, whether the difference calculating these two colour temperatures is greater than the colour temperature threshold value (the less coherence request to LED lamp bead colour temperature of colour temperature threshold value is higher) of user's setting, if be greater than colour temperature threshold value, then think that colour temperature consistance is defective, thus LED lamp is defective, continue to pick out underproof lamp pearl.Get average to all colour temperatures in array C [n], its average is denoted as take out color temperature value CCT minimum and maximum in array C [n] _max, CCT _min, compare with size, be greater than then think that colour temperature is CCT _minlamp pearl defective, otherwise think that colour temperature is CCT _maxlamp pearl defective, and the data of defective lamp pearl to be rejected from array C [n], from step 2, again select underproof lamp pearl;

V) make mean value computation respectively to red, green, blue three kinds of light intensity of lamp pearls all on light fixture, computing formula is as follows:

$\left.\begin{array}{c}{\stackrel{\‾}{I}}_r=(I_{r_1}+I_{r_2}+...+I_{r_n})/n\\ {\stackrel{\‾}{I}}_g=(I_{g_1}+I_{g_2}+...+I_{g_n})/n\\ {\stackrel{\‾}{I}}_b=(I_{b_1}+I_{b_2}+...+I_{b_n})/n\end{array}\right\}---\left(13\right)$

VI) if be less than colour temperature threshold value, the absolute value of the difference between the average then obtaining red, green, blue three kinds of light intensity of each lamp pearl and red, green, blue three kinds of light intensity of all lamp pearls respectively, and then summation operation is done to the absolute value of calculated difference, specific formula for calculation is as follows:

$S_{I_n}=\sqrt{{(I_{r_n}-{\stackrel{\‾}{I}}_r)}^2}+\sqrt{{(I_{g_n}-{\stackrel{\‾}{I}}_g)}^2}+\sqrt{{(I_{g_n}-{\stackrel{\‾}{I}}_g)}^2}---\left(14\right)$

Wherein in the present invention represent the absolute value sum of the difference in light fixture between red, green, blue three kinds of light intensity of the n-th lamp pearl and the average of red, green, blue three kinds of light intensity of all lamp pearls;

VII) define the one-dimension array S [n] (n equals the number of lamp pearl in LED lamp) that a length is n, will be worth by ascending order successively stored in (final minimum color temperature value incorporates in S [0], and maximal value incorporates in S [n-1]) in array S [n];

VIII) value in array S [n] is taken out, and the size of the Intensity threshold that the maximal value compared in S [n] array and user set (the less coherence request to LED lamp bead light intensity of Intensity threshold is higher), if the maximal value in S [n] array is greater than Intensity threshold, then think that light intensity consistance is defective, thus LED lamp is defective, and think that the lamp pearl that in S [n] array all values are greater than the Intensity threshold of user's setting corresponding is defective, if be less than Intensity threshold, then think that LED lamp is qualified.

Claims (8)

1. a kind of online screening technique of LED lamp tested based on brightness and colour temperature involved in the present invention, is characterized in that comprising: a kind of method of LED lamp bead RGB three primary colours light intensity data acquisition and processing, a kind of a kind of method of being screened LED lamp by the method for RGB three primary colours light intensity calculating LED lamp bead colour temperature, colour temperature according to each LED lamp bead in LED lamp and light intensity.

2. according to claim 1, it is characterized in that the method for described a kind of LED lamp bead RGB three primary colours light intensity data acquisition and processing is divided into two aspects and carries out, is the acquisition system of light intensity data on the one hand, is the disposal route of light intensity data on the other hand.

3. according to claim 2, it is characterized in that: the acquisition system of described light intensity data, primarily of 4 part compositions, is respectively optical filter, photoelectric conversion module, data selection passage, light intensity data acquisition module.

4. according to claim 2, it is characterized in that: the disposal route of described light intensity data comprises the calculating of data filtering process, light intensity data.

5. according to claim 4, it is characterized in that: described filter processing method comprises mean filter and power frequency filtering, the voltage signal that red, green, blue three kinds of light intensity of final n-th lamp pearl are corresponding can be expressed as:

$\left\{\begin{array}{c}{V}_{r_n}=({\stackrel{\‾}{V}}_{r_{n}0}+{\stackrel{\‾}{V}}_{r_{n}1}+{\stackrel{\‾}{V}}_{r_{n}2}+{\stackrel{\‾}{V}}_{r_{n}3}+{\stackrel{\‾}{V}}_{r_{n}4}+{\stackrel{\‾}{V}}_{r_{n}5}+{\stackrel{\‾}{V}}_{r_{n}6}+{\stackrel{\‾}{V}}_{r_{n}7}+{\stackrel{\‾}{V}}_{r_{n}8}+{\stackrel{\‾}{V}}_{r_{n}9})/10\\ V_{g_n}=({\stackrel{\‾}{V}}_{g_{n}0}+{\stackrel{\‾}{V}}_{g_{n}1}+{\stackrel{\‾}{V}}_{g_{n}2}+{\stackrel{\‾}{V}}_{g_{n}3}+{\stackrel{\‾}{V}}_{g_{n}4}+{\stackrel{\‾}{V}}_{g_{n}5}+{\stackrel{\‾}{V}}_{g_{n}6}+{\stackrel{\‾}{V}}_{g_{n}7}+{\stackrel{\‾}{V}}_{g_{n}8}+{\stackrel{\‾}{V}}_{g_{n}9})/10\\ V_{b_n}=({\stackrel{\‾}{V}}_{b_{n}0}+{\stackrel{\‾}{V}}_{b_{n}1}+{\stackrel{\‾}{V}}_{b_{n}2}+{\stackrel{\‾}{V}}_{b_{n}3}+{\stackrel{\‾}{V}}_{b_{n}4}+{\stackrel{\‾}{V}}_{b_{n}5}+{\stackrel{\‾}{V}}_{b_{n}6}+{\stackrel{\‾}{V}}_{b_{n}7}+{\stackrel{\‾}{V}}_{b_{n}8}+{\stackrel{\‾}{V}}_{b_{n}9})/10\end{array}\right..$

6. according to claim 4, it is characterized in that: the calculating of described light intensity data, red, green, blue three kinds of light intensity of its final n-th lamp pearl can be expressed as:

$\left\{\begin{array}{c}{I}_{r_n}=k_r{V}_{r_n}+b_r\\ I_{g_n}=k_g{V}_{g_n}+b_g\\ I_{b_n}=k_b{V}_{b_n}+b_b\end{array}\right.$

Wherein k _r, k _g, k _b, b _r, b _r, b _rconversion coefficient between light intensity and voltage.

7. according to claim 1, it is characterized in that: a kind of described method by RGB three primary colours light intensity calculating LED lamp bead colour temperature comprises following three steps:

I) conversion relational expression that the rgb value using CIE (International Commission on Illumination) to recommend is converted to XYZ value obtains XYZ tristimulus values, and its conversion relational expression is as follows:

$\left\{\begin{array}{c}X=0.3568R+0.2889G+0.2132B\\ Y=0.1173R+0.9000G-0.0611B\\ Z=0.0095R-0.5294G+1.6196B\end{array}\right.$

Wherein parameter R, G, B respectively by replace;

XYZ value is converted to chromaticity coordinates by the formula II) using CIE to recommend, and its expression formula is as follows:

$\left\{\begin{array}{c}x=\frac{X}{X+Y+Z}\\ y=\frac{Y}{X+Y+Z}\end{array}\right.;$

III) adopt approximate formula method that chromaticity coordinates is converted to colour temperature, its expression formula is as follows:

CCT＝499K ³+3525K ²+6823.3K+5520.33

Wherein K=(x-0.3320)/(0.1858-y), CCT represents colour temperature.

8. according to claim 1, it is characterized in that: described a kind of colour temperature according to each LED lamp bead in LED lamp and light intensity comprise the method that LED lamp is screened to screen LED lamp according to colour temperature and light intensity and to pick out underproof lamp pearl, and its concrete steps are as follows:

I) colour temperature of lamp pearls all in LED lamp is numbered, is denoted as CCT respectively ₁, CCT ₂... CCT _n;

II) the one-dimension array C [n] (n equals the number of lamp pearl in LED lamp) that a length is n is defined;

III) by CCT ₁, CCT ₂... CCT _nascendingly to sort, after having sorted by ascending order stored in (final minimum color temperature value incorporates in C [0], and maximal value incorporates in C [n-1]) in array C [n];

IV) color temperature value in C [0] and C [n-1] is taken out, whether the difference calculating these two colour temperatures is greater than the colour temperature threshold value (the less coherence request to LED lamp bead colour temperature of colour temperature threshold value is higher) of user's setting, if be greater than colour temperature threshold value, then think that colour temperature consistance is defective, thus LED lamp is defective, continue to pick out underproof lamp pearl; Get average to all colour temperatures in array C [n], its average is denoted as take out color temperature value CCT minimum and maximum in array C [n] _max, CCT _min, compare with size, be greater than then think that colour temperature is CCT _minlamp pearl defective, otherwise think that colour temperature is CCT _maxlamp pearl defective, and the data of defective lamp pearl to be rejected from array C [n], from step 2, again select underproof lamp pearl;

V) make mean value computation respectively to red, green, blue three kinds of light intensity of lamp pearls all on light fixture, computing formula is as follows:

$\left\{\begin{array}{c}{\stackrel{\‾}{I}}_r=(I_{r_1}+I_{r_2}+...+I_{r_n})/n\\ {\stackrel{\‾}{I}}_g=(I_{g_1}+I_{g_2}+...+I_{g_n})/n\\ {\stackrel{\‾}{I}}_b=(I_{b_1}+I_{b_2}+...+I_{b_n})/n\end{array}\right.$

VI) if be less than colour temperature threshold value, the absolute value of the difference between the average then obtaining red, green, blue three kinds of light intensity of each lamp pearl and red, green, blue three kinds of light intensity of all lamp pearls respectively, and then summation operation is done to the absolute value of calculated difference, specific formula for calculation is as follows:

$S_{I_n}=\sqrt{{(I_{r_n}-{\stackrel{\‾}{I}}_r)}^2}+\sqrt{{(I_{g_n}-{\stackrel{\‾}{I}}_g)}^2}+\sqrt{{(I_{g_n}-{\stackrel{\‾}{I}}_g)}^2}$

Wherein in the present invention represent the absolute value sum of the difference in light fixture between red, green, blue three kinds of light intensity of the n-th lamp pearl and the average of red, green, blue three kinds of light intensity of all lamp pearls;

VII) define the one-dimension array S [n] (n equals the number of lamp pearl in LED lamp) that a length is n, will be worth by ascending order successively stored in (final minimum color temperature value incorporates in S [0], and maximal value incorporates in S [n-1]) in array S [n];

VIII) value in array S [n] is taken out, and the size of the Intensity threshold that the maximal value compared in S [n] array and user set (the less coherence request to LED lamp bead light intensity of Intensity threshold is higher), if the maximal value in S [n] array is greater than Intensity threshold, then think that light intensity consistance is defective, thus LED lamp is defective, and think that the lamp pearl that in S [n] array all values are greater than the Intensity threshold of user's setting corresponding is defective, if be less than Intensity threshold, then think that LED lamp is qualified.