Point light source light field distribution testing device

Abstract

The utility model provides a point light source light field distribution testing device, which comprises a daylighting piece, a diffusion sheet and a shooting device, a point light source piece is conveyed to a testing station by a conveying device, the testing station is arranged below the daylighting piece, the daylighting piece is arranged close to the point light source piece, the diffusion sheet is arranged at the top of the daylighting piece, and the shooting device is arranged on the testing station. The light collecting piece is arranged above the spot light source, the shooting device is arranged above the diffusion sheet, the light collecting piece collects light rays emitted by the spot light source at different angles, the light rays are scattered at the diffusion sheet, and the shooting device collects images on the diffusion sheet. According to the scheme, color testing of the light source and light field distribution are combined together, collection of all light emitting information of a point light source material can be completed through one-time testing, and the requirement for automatic testing of the LED light field is met.

Description

Technical Field

[0001] This utility model belongs to the field of LED light source testing, and in particular relates to a point light source light field distribution testing device. Background Technology

[0002] In various fields such as lighting and displays, each light-emitting device often integrates multiple LEDs. If one LED is defective, the entire light-emitting module will be defective, leading to further losses. Currently, commonly used LED colorimetric testing technology, in automated batch testing equipment, generally uses an integrating sphere to collect the light emitted by the LEDs. The integrating sphere is fixed on the test station, and each LED is sequentially transported to the test station via a transmission device to be lit and its optical characteristics tested. After entering the integrating sphere, the light emitted by the LED undergoes multiple diffuse reflections and is finally guided from the light outlet on the right side through an optical fiber to a spectrometer for single-point testing of the LED's color. However, because the light undergoes countless diffuse reflections, the intensity and color distribution information at different angles is lost. If the LED exhibits uniform colorimetric characteristics at different angles, there is no effective means of detection.

[0003] Existing emission angle detection technology uses a rotating device to rotate an LED by ±90 degrees. A fixed photometric probe then detects and records the light intensity at the current angle of the LED. Finally, the emission curve of the light source is reconstructed by integrating the data. However, this method has many application limitations. It can only test the light intensity distribution, not the color distribution and color difference. Since it is still a single-point test, a rotating device is required to rotate the light source under test, resulting in a slow testing speed, with each test taking several seconds to tens of seconds. The test data is limited, as it can only test the light field distribution on a certain axis plane of the light source under test, and cannot test the light field distribution on all other axis planes. The instruments are expensive, require a large space, and have a long testing time. In practical applications, it can only be used as a sampling inspection method and cannot achieve batch testing of the light source under test. Summary of the Invention

[0004] The purpose of this invention is to provide a point light source light field distribution testing device, which aims to solve the problems existing in the above-mentioned existing testing methods.

[0005] This invention is implemented as follows: a point light source light field distribution testing device includes a light-collecting component, a diffuser, and an imaging device. The point light source is delivered to the testing station by a conveying device. The testing station is located below the light-collecting component, and the light-collecting component is positioned close to the point light source. The diffuser is positioned on top of the light-collecting component, and the imaging device is positioned above the diffuser. The light-collecting component collects light emitted from the point light source at different angles, which is scattered at the diffuser. The imaging device captures the image on the diffuser.

[0006] A further technical solution of this utility model is: the light-collecting component adopts a fiber optic bundle prism, and the fiber optic bundle prism is provided with a number of regularly arranged capillary fiber arrays. The light emitted by the point light source component enters from one end of the capillary fiber array, is transmitted along the vertical direction of the capillary fiber array, and finally exits from the top plane of the fiber optic bundle prism to the diffuser.

[0007] A further technical solution of this utility model is that the angle range of the light emitted by the point light source collected by the fiber optic bundle prism is ±75 to 85 degrees.

[0008] A further technical solution of this utility model is: the light-collecting component adopts a convex lens group, the convex lens group includes several stacked convex lenses, light emitted from the point light source component at different angles enters the bottom convex lens, is refracted by several convex lenses, and is emitted from the top convex lens to the diffuser sheet, where the light is narrowed to a range of ±45 degrees when emitted.

[0009] A further technical solution of this utility model is that the angular range of the light emitted by the point light source collected by the convex lens group is ±75 to 85 degrees.

[0010] A further technical solution of this utility model is that the convex lens group includes at least two convex lenses.

[0011] A further technical solution of this utility model is: the shooting device includes a camera and a lens, the lens is disposed at the bottom of the camera, the lens faces the diffuser, and the image of the diffuser is imaged onto the sensor chip of the camera through the lens.

[0012] A further technical solution of this utility model is that the point light source, the light-collecting element, the diffuser, and the shooting device are located on the same vertical line.

[0013] The beneficial effects of this utility model are: this solution combines the color test of the light source with the light field distribution, so as to complete the collection of all luminous information of the point light source material in one test, and meet the needs of automated testing of LED light field. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the light-collecting component using a fiber optic bundle prism in this utility model;

[0015] Figure 2 This is a schematic diagram of the interior of the fiber optic bundle prism of this utility model;

[0016] Figure 3 This is a schematic diagram of the convex lens group used in the light-collecting component of this utility model;

[0017] Figure 4This is a schematic diagram of the image parameters on the diffuser sheet in this utility model;

[0018] Figure 5 This is a diagram showing the original data distribution of the Lambertian light source in this utility model;

[0019] Figure 6 This is a data distribution diagram after correction of the Lambertian light source in this utility model.

[0020] Figure reference numerals: 1-point light source, 2-fiber optic bundle prism, 3-diffuser, 4-lens, 5-camera, 6-convex lens, 7-capillary fiber array. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to directions in the accompanying drawings, while the terms "bottom surface," "top surface," "inner," and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0022] This utility model provides a point light source light field distribution testing device, including a light-collecting component, a diffuser 3, and an imaging device. The point light source 1 is delivered to the testing station by a conveying device. The testing station is located below the light-collecting component and is positioned close to the point light source 1. The diffuser 3 is positioned on top of the light-collecting component, and the imaging device is positioned above the diffuser 3. The light-collecting component collects light emitted from the point light source at different angles, which is scattered at the diffuser 3. The imaging device captures the image on the diffuser 3.

[0023] This invention combines color testing and light field distribution of a light source with two novel approaches, enabling the collection of all luminescence information of a point light source material in a single test, thus meeting the requirements for automated testing of LED light fields.

[0024] The first scheme uses a fiber optic bundle prism 2 device with a semi-circular arc surface at the bottom. Light from different directions emitted from the light source enters from the ends of each capillary fiber array 7 on the arc surface of the prism, then is propagated along the vertical direction of the fiber, and finally exits from the upper plane of the fiber optic bundle prism 2. This guides light from different angles of the light source to the same imaging plane, which facilitates further image data acquisition and makes full-field acquisition possible.

[0025] The first scheme uses a fiber bundle prism 2 as the main light-collecting device. The fiber bundle prism 2 contains a large array of regularly arranged capillary fibers 7, which can transmit the light color of each point at one end to the other end. The advantage of this scheme is that it only has a single light-collecting component, has low requirements for the accuracy of structural positioning, and is suitable for testing light sources with small size.

[0026] The point light source 1 is located at the bottom of the device. To collect as much light as possible from the point light source 1, it should be as close as possible to the fiber optic bundle prism 2. When used as a manual instrument, the point light source 1 can be completely close to the fiber optic bundle prism 2, allowing the prism 2 to collect all the light emitted from it. When used as an online automated instrument, the point light source 1 should be approximately 1-2 mm away from the bottom of the fiber optic bundle prism 2. This is because during online testing, the point light source 1 passes horizontally under the fiber optic bundle prism 2 one by one via a conveyor, and a sufficient safety distance must be maintained to avoid collisions. A conveyor belt can be used as the conveyor. In this case, the fiber optic bundle prism 2 can collect light from the point light source 1 within ±75 to ±85 degrees. However, considering that the point light source 1 is typically Lambertian light, the light at the edge angles is already very weak, and its impact on collecting most of the light from the point light source 1 is minimal.

[0027] Light emitted from the LED enters the fiber optic bundle prism 2. Inside the prism is a dense array of vertically arranged quartz capillary fibers 7, with the number of capillary fibers reaching the millions. Each ray of light incident on the bottom arc surface of the fiber optic bundle prism 2 is vertically guided to the top plane of the fiber optic bundle prism 2. A diffuser 3 covers the top of the fiber optic bundle prism 2, causing the light rays emitted from the top of the fiber optic bundle prism 2 to be scattered on the diffuser 3. This creates a light color distribution image on the diffuser 3, where each point corresponds to the color of light emitted from the light source at a different angle, effectively projecting the light field emitted by the light source onto a plane. (See attached diagram.) Figure 1 As shown, there is a gap between the fiber optic bundle prism 2 and the diffuser 3. In practical applications, the fiber optic bundle prism 2 and the diffuser 3 are in close contact. After the image on the diffuser 3 passes through the lens 4, it is imaged onto the sensor chip of the camera 5. The image on the diffuser 3 is then captured by the camera 5. The camera 5 here can be an industrial camera.

[0028] The second approach uses a multi-curved convex lens group. Light emitted from the light source from different directions enters the convex lens 6 and is refracted multiple times by the convex lens 6, changing the direction of the light source and narrowing the original emission angle of ±90 degrees to ±45 degrees or less. Then, a diffuser 3 is placed on the upper end of the convex lens group, so that different angles can be projected onto the same imaging plane, which facilitates further image data acquisition.

[0029] A convex lens group is used as the main light-collecting device. The convex lens group consists of 2-3 convex lenses 6. Since the large-size fiber bundle prism 2 is expensive and difficult to manufacture, the convex lens group is more suitable when the light source being measured is relatively large.

[0030] The point light source 1 is located at the bottom of the device. In order to collect as much light as possible from the point light source 1, it should be as close as possible to the convex lens group. When used as a manual instrument, the point light source 1 can be completely close to the convex lens group so that the convex lens group can collect all the light emitted from the point light source 1. When used as an online automated instrument, the point light source 1 is about 1-2 mm away from the bottom of the convex lens group. This is because during online testing, the point light source 1 passes horizontally under the convex lens group one by one through the conveyor device. To avoid collisions with the convex lens group, a sufficient safety distance needs to be maintained. At this time, the convex lens group can collect light from the point light source 1 within ±75 to ±85 degrees.

[0031] Light emitted from the point light source 1 enters the convex lens group, and the emission angle of the light source is gradually narrowed by several convex lenses 6. A diffuser 3 is placed on top of the convex lens group, causing the light rays emitted from the convex lens group to be scattered on the diffuser 3. In this way, a light color distribution image is formed on the diffuser 3, where each point corresponds to the color of light emitted by the light source from a different angle, that is, the light field emitted by the light source is projected onto a plane. The image on the diffuser 3 is then imaged onto the sensor chip of the camera 5 after passing through the lens 4, and the image on the diffuser 3 is acquired by the camera 5 through shooting.

[0032] The testing method for this solution is as follows:

[0033] Data Acquisition and Processing. An industrial camera placed above diffuser 3 acquires images of diffuser 3. The color and brightness of each pixel in the image correspond to the color and intensity of light emitted from the light source at each azimuth angle; that is, this image contains all the light field information of the light source. The color attribute is obtained by analyzing the RGB pixel values ​​of each point captured by the imaging device. The weighted sum of the RGB pixel values ​​of each point captured by the imaging device yields the light intensity value of each point light source.

[0034] In the first approach, it is necessary to obtain the pixel coordinates of the captured image corresponding to each azimuth angle of the light source. This requires calculating the physical coordinates (x, y) of the light rays on diffuser 3 for each different vertical tilt angle and horizontal rotation angle. The corresponding calculation formulas are as follows:

[0035] θv: The angle between the ray and the perpendicular normal;

[0036] θh: The angle between the light rays and the horizontal plane;

[0037] x: The physical coordinates x of the projection of the light ray onto diffuser 3;

[0038] y: The physical coordinates of the light ray projected onto diffuser 3;

[0039] r: Radius of the concave surface at the bottom of the beam prism;

[0040] h: The height of the light source being measured from the center of the concave surface at the bottom of the beam prism;

[0041] A: The arm length between the projection point of the light ray on diffuser 3 and the center point;

[0042]

[0043] x = sinθ h ·A

[0044] y = cosθ h ·A.

[0045] In the second approach, since the color camera captures red, green, and blue images on diffuser 3, and different colors of light have different refractive indices due to their different wavelengths, they ultimately form light spot distributions of different sizes on diffuser 3. Therefore, it is necessary to separate the red, green, and blue layers of the image and obtain the corresponding color pixels based on the light spot distribution of different layers. Each light path at different azimuth angles is calibrated. By comparing the coordinates of the laser spots in the captured images with those of lasers of different azimuths and colors, the correspondence between the light color at each point and its corresponding coordinate point in the image is deduced. The corresponding color pixels are obtained based on the light spot distribution of different layers. The color attribute of each point of the point light source is obtained from the RGB pixel values ​​of each pixel. The light intensity attribute of the point light source is obtained by weighted summation of the RGB pixel values ​​of each pixel, resulting in an RGB array value that constitutes point cloud data of the light field distribution. Based on the light field distribution and characteristics of different tested light sources, their emission characteristics are analyzed, and it is determined whether they meet the test standards.

[0046] The second approach differs from the first only in the method of light propagation and collection; both ultimately use an imaging device, so the software for analyzing parameter compliance is identical. However, in obtaining the image coordinates corresponding to each luminous point, due to the complexity of the lens's optical path and considering the refractive index differences of the three primary colors, red, green, and blue lasers are used separately. Each optical path at different azimuth angles is calibrated. By comparing the laser beams of different orientations and colors with the laser spot coordinates in the captured image, the correspondence between the light color of each point and its corresponding coordinates in the image is deduced, and a series equation formula for azimuth angle and coordinate position is fitted.

[0047] In the first scheme, due to the different angles at which light rays emitted from different azimuth angles of the light source enter the fiber bundle prism 2, the coupling efficiency varies. Combined with factors such as the diffuser plate and camera lens distortion, the intensity distribution of each pixel in the image ultimately captured by camera 5 is not entirely equal to the light intensity emitted from each azimuth angle of the light source, although the intensity of each pixel is proportional to the theoretical value. Similarly, in the second scheme, due to the difference in refractive index of the convex lens, the intensity distribution of each pixel in the image ultimately captured by camera 5 is not entirely equal to the light intensity emitted from each azimuth angle of the light source. Therefore, a standard light source can be designed. The RGB values ​​of the pixel positions obtained by the imaging device are only the raw values ​​captured by the camera. Due to attenuation after passing through the optical path, intensity calibration is necessary. A standard Lambertian beam is used to illuminate the optical path, and the correction coefficient for each point is calculated by dividing the theoretical value by the raw value. A Lambertian beam is placed at the sample acquisition position of this device and lit. Assuming the RGB pixel values ​​acquired by the camera are I... R I G I B Let θv be the angle between the ray and the perpendicular normal, and Let It be the intensity at the tip of the Lambertian ray. The formula is calculated as follows:

[0048] Intensity value of Lambert rays at a certain azimuth angle:

[0049] I s =I t ·cosθv

[0050] Correction factor for each pixel's RGB value:

[0051]

[0052]

[0053] Since the color and intensity of the standard light source at each azimuth angle are known, the compensation coefficient for each azimuth angle is calculated by testing the standard light source. The bit value of each pixel after compensation is the actual value of the light source under test. The RGB array values ​​after coefficient correction constitute the point cloud data of the light field distribution. Based on the light field distribution and characteristics of different light sources under test, corresponding algorithms are written to analyze their luminescence characteristics and determine whether they meet the test standards.

[0054] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A point light source light field distribution testing device, characterized in that, The device includes a light-collecting component, a diffuser, and an imaging device. The point light source is delivered to the testing station by a conveying device. The testing station is located below the light-collecting component and is positioned close to it. The diffuser is positioned on top of the light-collecting component, and the imaging device is positioned above the diffuser. The light-collecting component collects light emitted from the point light source at different angles, which is then scattered at the diffuser. The imaging device captures the image on the diffuser.

2. The point light source light field distribution testing device according to claim 1, wherein, The light-collecting element is a fiber bundle prism, which contains a number of regularly arranged capillary fiber arrays. The light emitted by the point light source enters from one end of the capillary fiber array, is transmitted along the vertical direction of the capillary fiber array, and finally exits from the top plane of the fiber bundle prism to the diffuser.

3. The point light source light field distribution testing device according to claim 2, wherein, The angle range of the light emitted by the point light source collected by the fiber optic bundle prism is ±75~85 degrees.

4. The point light source light field distribution testing device according to claim 1, wherein, The light-collecting element adopts a convex lens group, which includes several stacked convex lenses. Light emitted from the point light source at different angles enters the bottom convex lens, is refracted by several convex lenses, and is emitted from the top convex lens to the diffuser. When emitted, the light is narrowed to a range of ±45 degrees.

5. The point light source light field distribution testing device according to claim 4, characterized in that, The convex lens group collects light emitted from the point light source in an angle range of ±75~85 degrees.

6. The point light source light field distribution testing device according to claim 4, characterized in that, The convex lens group contains at least two convex lenses.

7. The point light source light field distribution testing device according to claim 1, wherein, The shooting device includes a camera and a lens. The lens is located at the bottom of the camera and faces the diffuser. The image of the diffuser is imaged onto the sensor chip of the camera through the lens.

8. The point light source light field distribution testing device according to claim 1, wherein, The point light source, light-collecting element, diffuser, and imaging device are located on the same vertical line.

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