CN104977155A - Rapid measurement method of LED light distribution curve - Google Patents
Rapid measurement method of LED light distribution curve Download PDFInfo
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- CN104977155A CN104977155A CN201510387472.1A CN201510387472A CN104977155A CN 104977155 A CN104977155 A CN 104977155A CN 201510387472 A CN201510387472 A CN 201510387472A CN 104977155 A CN104977155 A CN 104977155A
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Abstract
The invention discloses a rapid measurement method of an LED light distribution curve. The method comprises the following steps that: (1), a pixel coordinate of an image formed by an image sensor and an LED luminous intensity space coordinate are calibrated, thereby realizing one-to-one mapping of LED luminous intensities and exit angles; (2), the image sensor shoots an LED light spot image formed on a receiving screen and a non-LED-light-spot receiving screen background image and a computer reads the images to light distribution curve measurement software; (3), image subtraction is carried out to deduct background interference information; (4), Gamma correction is carried out on images with background deduction; (5), gravity center marking is carried out on the images after Gamma correction; (6), pixel point gray values of horizontal bands where the image gravity centers are located are extracted; (7), light intensity correction is carried out; (8), a light distribution curve is drawn automatically according to a light intensity correction formula obtained by the step (7). The method has advantages of high operability, fast measurement speed, high environmental adaptation, and visual measurement result.
Description
Technical field
The present invention relates to applied optics field, particularly a kind of LED distribution curve flux method for fast measuring.
Background technology
Semiconductor light-emitting-diode LED is a kind of important optoelectronic device, and the light source such as incandescent lamp, fluorescent light of its principle of luminosity and traditional lighting has very big-difference, and optical characteristics is also different, and this takes corresponding adjustment with regard to requiring to the measuring method of LED photovoltaic characteristic.
The measurement of current LED radiation quantities, as luminous flux, colour temperature measurement can realize rapid, and distribution curve flux is as the important parameter of reflection light fixture light distribution situation, it is the important evidence instructing Lighting Design and light fixture to select, measure length consuming time, never have a kind of method of Quick Measurement for a long time.
The strong space distribution measuring method of tradition LED light mainly contains three kinds, rotary reflective mirror, motion reflector type and rotating lamp formula.The measurement of central rotation reflector type needs measured light to make class circular motion in a sizable spatial dimension, catoptron must rotate with identical angular velocity reverse sync with main shaft with asessory shaft simultaneously, and this metering system requires high to the stability of photoluminescence of measured light and system each axle synchronous axial system; Motion reflector type measuring method does motion on a large scale without the need to measured light in space, but light beam direction in measuring process that measured light reflexes on detector can change at any time, if detector sensitivity is in all directions inconsistent, photometric measurement result will be caused to there is comparatively big error; Rotation sweep is measured, and modal measuring method is employing photometric detector, and LED light source can be selected motionless, and photometric detector is around its rotation sweep, and also rotatable photometric detector is motionless, and LED light source rotates around a dead center point.The measuring method test duration of this rotation sweep is tediously long, poor real, and in Measuring Time, the junction temperature of LED may rise, and luminescence efficiency is declined, light intensity decreasing, cause the early stage of measuring process and later stage light intensity data inconsistent, cause larger measuring error.
The development of LED is very fast, and method of testing and testing level also should grow with each passing hour.Along with improving constantly of digital imaging techniques, by the process of digital picture and analysis, make by Luminance Distribution in image range to reflect that the true light distribution of reference object becomes possibility.
Summary of the invention
The present invention is long for solving traditional LED distribution curve flux test duration, and proving installation is complicated, the problem of testing time-effectiveness difference, proposes a kind of LED distribution curve flux method for fast measuring.
For realizing above goal of the invention, the technical scheme of employing is:
A kind of LED distribution curve flux method for fast measuring, comprises the following steps:
S1. by imageing sensor form hot spot on the pixel coordinate of image and LED receiving screen Strength Space coordinate demarcate, realize LED luminous intensity and light shooting angle maps one by one;
S2. the LED light spot image that formed and without receiving screen background image during LED illumination on imageing sensor shooting receiving screen, computing machine reading images is in distribution curve flux Survey Software;
S3. by Digital Image Processing function in software by image subtraction, background correction interfere information;
S4. be Gamma to the image of background correction to correct;
S5. the image binaryzation after Gamma being corrected, search binary edge and screen white region from black background, the area distributions of statistics marked area, the total number of regional pixel in the total also computed image in viewing area, find out area the maximum in each region, be labeled as center of gravity;
S6. center of gravity is extracted, accurate with the behavior of hot spot center of gravity place, respectively get 8 row grey scale pixel values up and down stored in numerical matrix, the every column data of this matrix is averaged, each column data mean value is approximately the gray-scale value that hot spot center of gravity is expert at;
S7. according to the calibration result of step 1, light intensity correction is done to the LED luminescent image after Gamma correction;
S8. LED distribution curve flux is automatically drawn according to step 7 gained correction formula.
LED receiving screen in step S1 is cylindrical translucent receiving screen, bulb-shaped translucent receiving screen, or the general translucent receiving screen of arc, LED is placed on the axial centerline of receiving screen, and LED, LED receiving screen and imageing sensor three keep coaxial relation.
Imageing sensor in step S1, S2 is CCD camera or CMOS camera.
In step S2, distribution curve flux Survey Software is the distribution curve flux Survey Software possessing Digital Image Processing function with Matlab platform development, and computing machine reads in single picture to software every kind of a situation and processes.
The full color passage of Gamma calibration object obtain to by imageing sensor LED luminescent image in step S4.
Compared with prior art, the invention has the beneficial effects as follows:
LED distribution curve flux method for fast measuring provided by the invention has rapidity, be different from the scanning method of traditional measurement distribution curve flux completely, not to each position angle scanning survey one by one, only imageing sensor need be used to take projected spot figure and the hot spot receiving screen Background of LED to be measured, by carrying out color range computing based on the software that Matlab platform is developed, calculate the strong correction formula of LED light, LED distribution curve flux can be obtained, in the error range allowed, one-shot measurement can be completed in several seconds.The present invention is conceived to the deficiency of traditional LED distribution curve measuring method, the method for fast measuring that a kind of workable, environmental suitability is strong, measurement result has intuitive is proposed, eliminate the measuring process of classic method complexity, shorten the Measuring Time that classic method is tediously long, the object of Quick Measurement can be realized in the scope that error allows, there is very high using value.
Accompanying drawing explanation
Fig. 1 is the schematic top plan view of preferred embodiment provided by the invention;
Fig. 2 is Quick Measurement LED distribution curve flux effect schematic diagram in preferred embodiment provided by the invention;
Fig. 3 is workflow diagram of the present invention.
Embodiment
Accompanying drawing, only for exemplary illustrated, can not be interpreted as the restriction to this patent;
Below in conjunction with drawings and Examples, the present invention is further elaborated.
Embodiment
Be illustrated in figure 1 the schematic top plan view of provided by the invention one better embodiment, comprise LED 1, cylindrical translucent receiving screen 2 that bottom surface radius is 10cm, coaxial CCD camera 3 of placing and the computing machine 4 be connected with CCD camera.
As shown in Figure 3, a kind of LED distribution curve flux method for fast measuring provided by the invention comprises the following steps:
S1. by CCD camera become the volume coordinate of spot intensity on the pixel coordinate of image and LED receiving screen to demarcate, realize LED luminous intensity and light shooting angle maps one by one.Design the cylindrical translucent receiving screen that a bottom surface radius is 10cm, the luminescent center of LED is on the axis perpendicular to this cylindrical receiver screen bottom surface, receiving screen each point on horizontal line residing for LED is 10cm to LED luminescent center distance simultaneously, a length is selected to be 31.4cm and the demarcation band of 36 deciles, coat chequered with black and white color respectively, be attached to receiving screen by-level band position, the central angle of length correspondence 5 ° on receiving screen of each white or black region, CCD camera shooting receiving screen demarcates band, the change of gray scale between band pixel is demarcated by distribution curve flux Survey Software record, realize pixel coordinate one_to_one corresponding in LED luminous position central angle and image,
Formed LED light spot image and without receiving screen background image during LED illumination on S2.CCD camera shooting receiving screen, computing machine reading images in distribution curve flux Survey Software, products for further process;
S3. by Digital Image Processing function in software by two image subtractions, background correction interfere information;
S4. be Gamma to the image of background correction to correct, adopt the gamma coefficient of 0.43445 to do Gamma correction to the full color passage that CCD camera institute obtains LED luminescent image;
S5. the image binaryzation process after Gamma being corrected, search binary edge and screen white region from black background, the area distributions of statistics marked area, the total number of regional pixel in the total also computed image in viewing area, find out area the maximum in each region and be marked, other region is set to 0.Draw an elliptic region at area maximum, obtain under pixel meaning and to have with region that the long and short axle of transverse of standard second order centre distance is short, eccentricity, thus extract the barycenter in this region, be the center of gravity (x of image spot
0, y
0);
S6. in the image after correcting through Gamma, accurate with the behavior of hot spot center of gravity place, respectively get 8 row grey scale pixel values up and down stored in numerical matrix, the every column data of this matrix is averaged, each column data mean value is approximately the gray-scale value that hot spot center of gravity is expert at, namely using hot spot center of gravity be 0 ° to the left and right two ends each 0.5 ° as a test point, extract the gray-scale value of this pixel in image stored in numerical matrix;
S7. light intensity correction is done to the LED luminescent image after Gamma correction.As shown in Figure 1, LED luminescence is distributed as the light of arbitrarily angled θ, and the direction of CCD camera and this light intensity direct projection exists departing from of α angle, if O point in the center of circle is tested LED position, CCD camera position at P point, OP=L, OA=r, suppose any point C within the scope of the hot spot that can obtain in CCD camera, corresponding pixel wide is h, and the subtended angle being in central horizontal line at O point is θ, BC=h=rsin θ, BP=l=L-d, then the maximum hot spot angular range that CCD camera can obtain is ± θ
m, cos θ
mthe angle of=r/L, CP and OC is α, α=θ+β, then
the hot spot of LED projection is I in the actual light intensity of C point
real, CCD camera become the light intensity of image to be I
image, therefore to close between respective pixel point gray-scale value and the light intensity of this point in image be I
image=I
realcos α, therefore actual light intensity is modified to
S8. LED distribution curve flux is automatically drawn according to step 7 gained light intensity correction formula.
In sum, a kind of LED distribution curve flux method for fast measuring that the present invention proposes, focus on utilizing digital image-forming and image processing techniques to analyze the distribution of LED luminous intensity, and carrying out color range computing based on the software that Matlab platform is developed, light intensity correction, reaches the object of Quick Measurement distribution curve flux.
Above embodiment is only and technological thought of the present invention is described, can not limit protection scope of the present invention with this, every technological thought proposed according to the present invention, and any change done on technical scheme is inherited, all falls within scope.
Claims (7)
1. a LED distribution curve flux method for fast measuring, is characterized in that comprising the steps:
S1. by imageing sensor form hot spot on the pixel coordinate of image and LED receiving screen Strength Space coordinate demarcate, realize LED luminous intensity and light shooting angle maps one by one;
S2. the LED light spot image that formed and without receiving screen background image during LED illumination on imageing sensor shooting receiving screen, computing machine reading images is in distribution curve flux Survey Software;
S3. by Digital Image Processing function in software by image subtraction, background correction interfere information;
S4. be Gamma to the image of background correction to correct;
S5. the image binaryzation after Gamma being corrected, search binary edge and screen white region from black background, the area distributions of statistics marked area, the total number of regional pixel in the total also computed image in viewing area, find out area the maximum in each region, be labeled as center of gravity;
S6. extract center of gravity, accurate with the behavior of hot spot center of gravity place, respectively get 8 row grey scale pixel values up and down stored in numerical matrix, to this matrix often row gray-scale value average, each column data mean value is approximately the gray-scale value that hot spot center of gravity is expert at;
S7. according to the calibration result of step 1, light intensity correction is done to the LED luminescent image after Gamma correction;
S8. LED distribution curve flux is automatically drawn according to step 7 gained correction formula.
2. LED distribution curve flux method for fast measuring as claimed in claim 1, is characterized in that: LED receiving screen is cylindrical translucent receiving screen, bulb-shaped translucent receiving screen, or the translucent receiving screen of arc, and LED is placed on the axial centerline of receiving screen.
3. LED distribution curve flux method for fast measuring as claimed in claim 1, is characterized in that: the imageing sensor in described step S1, S2 is CCD camera or CMOS camera.
4. LED distribution curve flux method for fast measuring as claimed in claim 1, is characterized in that: in described step S1, LED light source, hot spot receiving screen and imageing sensor three keep coaxial relation.
5. LED distribution curve flux method for fast measuring as claimed in claim 1, is characterized in that: described step S2 Computer reads in single picture to software every kind of a situation and processes.
6. LED distribution curve flux method for fast measuring as claimed in claim 1, is characterized in that: the full color passage of Gamma calibration object obtain to by imageing sensor LED luminescent image in described step S4.
7. LED distribution curve flux method for fast measuring as claimed in claim 1, is characterized in that: described distribution curve flux Survey Software is the distribution curve flux Survey Software possessing Digital Image Processing function with Matlab platform development.
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Cited By (6)
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| CN107044908A (en) * | 2016-12-30 | 2017-08-15 | 长安大学 | It is a kind of quickly to match somebody with somebody light detection method |
| CN110068448A (en) * | 2019-05-05 | 2019-07-30 | 深圳市康康网络技术有限公司 | Measurement method, device, terminal device and the readable storage medium storing program for executing of distribution curve flux |
| WO2019169821A1 (en) * | 2018-03-05 | 2019-09-12 | 深圳市奥拓电子股份有限公司 | Intelligent detection method and system for led lamp, and storage medium |
| CN110514406A (en) * | 2019-07-12 | 2019-11-29 | 佛山市青松科技股份有限公司 | A kind of detection method of LED lamp panel, electronic equipment and storage medium |
| WO2019237414A1 (en) * | 2018-06-13 | 2019-12-19 | 苏州晶品新材料股份有限公司 | Lossless real-time measurement method for junction temperature of led light source |
| CN112484967A (en) * | 2020-11-18 | 2021-03-12 | 深圳市汇顶科技股份有限公司 | Light intensity detection method, light intensity detection device, light intensity parameter determination method, light intensity parameter determination device, equipment and storage medium |
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Cited By (7)
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| CN110514406B (en) * | 2019-07-12 | 2021-04-06 | 佛山市青松科技股份有限公司 | Detection method of LED lamp panel, electronic equipment and storage medium |
| CN112484967A (en) * | 2020-11-18 | 2021-03-12 | 深圳市汇顶科技股份有限公司 | Light intensity detection method, light intensity detection device, light intensity parameter determination method, light intensity parameter determination device, equipment and storage medium |
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