阅读说明：本技术 基于高光谱的荧光粉发光特性透射式测试装置和方法 (Hyperspectrum-based transmission-type testing device and method for luminescent characteristics of fluorescent powder ) 是由 郭自泉 刘必靖 杨宸 林苡 吕毅军 高玉琳 陈忠 于 2019-10-14 设计创作，主要内容包括：基于高光谱的荧光粉发光特性透射式测试装置和方法,涉及发光器件领域,包括LED激发光源、荧光粉片、三维控制台、恒流源、控温模块、显微镜、高光谱仪和计算机；LED激发光源设于三维控制台上；恒流源连接LED激发光源；控温模块设于三维控制台上；荧光粉片置于LED激发光源的正上方；显微镜设于荧光粉片的上方；高光谱仪设于显微镜的上方,高光谱仪用于收集和处理显微镜透过的光并得到高光谱数据；计算机连接高光谱仪,计算机用于将接收的高光谱数据进行计算得到二维几何空间的荧光粉光学参数。可精确得到荧光粉像素级别的发光图像以及获得相应像素点上的光谱数据,从而精确地得到荧光粉微米尺度空间上发光特性。(A hyperspectral-based transmission-type testing device and method for the luminescent property of fluorescent powder relate to the field of luminescent devices and comprise an LED excitation light source, a fluorescent powder sheet, a three-dimensional control console, a constant current source, a temperature control module, a microscope, a hyperspectral meter and a computer; the LED excitation light source is arranged on the three-dimensional control table; the constant current source is connected with the LED excitation light source; the temperature control module is arranged on the three-dimensional console; the fluorescent powder sheet is arranged right above the LED excitation light source; the microscope is arranged above the fluorescent powder sheet; the hyperspectral meter is arranged above the microscope and used for collecting and processing light transmitted by the microscope and obtaining hyperspectral data; and the computer is connected with the hyperspectral spectrometer and is used for calculating the received hyperspectral data to obtain the optical parameters of the fluorescent powder in the two-dimensional geometric space. The luminescent image of the phosphor powder pixel level and the spectrum data on the corresponding pixel point can be accurately obtained, so that the luminescent characteristic of the phosphor powder in the micron-scale space can be accurately obtained.)

1. High spectrum-based transmission-type testing device for luminescent characteristics of fluorescent powder is characterized in that: the device comprises an LED excitation light source, a fluorescent powder sheet, a three-dimensional control platform, a constant current source, a temperature control module, a microscope, a hyperspectral meter and a computer;

the LED excitation light source is arranged on the three-dimensional control platform, and the three-dimensional control platform is used for adjusting the position of the LED excitation light source;

the constant current source is connected with the LED excitation light source and is used for providing constant current to drive the LED excitation light source;

the temperature control module is arranged on the three-dimensional control platform and is positioned at the bottom of the LED excitation light source, and the temperature control module is used for controlling the temperature of the LED excitation light source;

the fluorescent powder sheet is arranged right above the LED excitation light source;

the microscope is arranged above the fluorescent powder sheet and is used for transmitting the emission light of the fluorescent powder sheet and the excitation light of the LED excitation light source;

the hyperspectral meter is arranged above the microscope and used for collecting and processing light transmitted by the microscope and obtaining hyperspectral data;

the computer is connected with the hyperspectral spectrometer and used for calculating the received hyperspectral data to obtain the optical parameters of the fluorescent powder in the two-dimensional geometric space.

2. The hyperspectral-based transmission-type test device for the luminescent property of the fluorescent powder according to claim 1, which is characterized in that: the LED excitation light source is arranged at the bottom of the reflection cup, and the fluorescent powder sheet is arranged at the top of the reflection cup.

3. The hyperspectral-based transmission-type test device for the luminescent property of the fluorescent powder according to claim 1, which is characterized in that: the LED excitation light source comprises a blue or near-ultraviolet LED excitation light source.

4. A hyperspectral-based transmission-type test method for the luminescent characteristics of fluorescent powder is characterized by comprising the following steps:

1) placing an LED excitation light source on a temperature control module, setting the temperature of the temperature control module to be T, placing a transparent substrate right above the LED excitation light source, connecting the LED excitation light source with a constant current source, and setting a driving current to be I;

2) moving the three-dimensional control table, adjusting the transparent substrate to be under a microscope, enabling light emitted by the LED excitation light source to penetrate through the transparent substrate, entering the hyperspectral spectrometer through the microscope, collecting and processing the corresponding hyperspectral data by the hyperspectral spectrometer and the computer, and measuring the hyperspectral data to obtain two-dimensional photons of the LED excitation lightNumber distribution B_m×n；

3) Replacing the transparent substrate with a fluorescent powder sheet, and setting the current and temperature conditions same as those in the step 1);

4) moving the three-dimensional control table to enable the position of the fluorescent powder sheet to be the same as that in the step 2), repeating the process in the step 2), and measuring to obtain LED exciting light two-dimensional photon number distribution BB_m×nAnd the number distribution Y of the photons emitted from the phosphor_m×n；

5) And calculating the fluorescent powder conversion efficiency and the fluorescent powder quantum efficiency distribution of the two-dimensional geometric space of the fluorescent powder sheet.

5. The hyperspectral-based transmission-type test method for the luminescent property of the fluorescent powder according to claim 4, which is characterized in that: in the step 2), the total number B of the LED exciting light photons with different wavelengths of each pixel is obtained through integral calculation, and the corresponding two-dimensional matrix is marked as B_m×n：

In the step 4), the total number BB of the LED exciting light photons and the total number Y of the light photons emitted by the fluorescent powder of different wavelengths of each pixel are obtained through integral calculation, and the corresponding two-dimensional matrixes are BB_m×nAnd Y_m×n：

Where m, n represent the two-dimensional spatial position coordinates of the pixel.

6. The hyperspectral-based transmission-type test method for the luminescent property of the fluorescent powder according to claim 5, which is characterized in that: in step 5), the calculated phosphor conversion efficiency

wherein (lambda)₁,λ₂) Is the wave band of LED exciting light (lambda)₃,λ₄) The wavelength band in which the phosphor emits light.

Technical Field

The invention relates to the field of luminescent devices, in particular to a hyperspectral transmission type testing device and method for luminescent characteristics of fluorescent powder.

Background

A Light Emitting Diode (LED) is a semiconductor Light Emitting device that converts electrical energy into Light energy. In recent years, the solar cell panel has the advantages of energy conservation, environmental protection, small volume, long service life, high response speed and the like, and is widely applied to the application fields of illumination and display such as mobile phone backlight sources, display screens, plant illumination, traffic signals, automobile illumination, intelligent illumination and the like.

Current white LEDs are typically implemented using three main approaches. The first is that multiple single color LEDs emit light that is mixed to produce white light. The second method is to use a 430-470 nm blue LED to excite yellow fluorescent powder to form white light, is also the most common method for the current commercial LEDs, and has the characteristics of low cost, high luminous efficiency, simple process and the like. And the third is to use 350-400 nm near ultraviolet light to excite various fluorescent powders (such as red, green and blue three-primary-color fluorescent powders) to form white light.

In the second type of white LED, a mixture of phosphor and transparent silicone is typically applied directly to the LED chip surface and then cured. However, the package structure is prone to cause over 60% of light to be re-absorbed by the LED chip for exciting the phosphor, which causes the temperature of the LED device to increase, thereby affecting the light efficiency and reliability of the LED device. To effectively solve this problem, a packaging structure of a remote excited phosphor patch (remote phosphor) of an LED is proposed by the researchers in the industry. The detection of the luminescence characteristics of the fluorescent powder sheet has significant significance for guiding and improving the luminescence of the white light LED of the packaging structure.

At present, most of the luminescence property detection of fluorescent powder, fluorescent powder glue mixture or fluorescent powder sheet (in the invention, the fluorescent powder is called as the fluorescent powder for short) is stopped on the whole detection of the fluorescent powder. The specific method is to detect the luminous performance of the fluorescent powder excited by the blue LED chip through an integrating sphere and a spectrometer. For example, chinese utility model patent (CN 203259477U) discloses a fluorescent powder optical measurement device, which is configured with a plurality of excitation light sources, and flexibly switches the excitation light sources and the fluorescent powder to realize excitation measurement of a plurality of fluorescent powders. For example, chinese utility model patent (CN 201043952Y) discloses a fluorescent powder excitation spectrum measuring device, in which monochromatic light emitted from an excitation light source is vertically incident on a tray filled with fluorescent powder to measure the light emitted from the fluorescent powder. For example, chinese patent application (CN 107228849B) discloses a transmission-type testing apparatus for temperature-variable spectral characteristics of white LED fluorescent powder, which uses a transmission-type measuring method to measure the spectral characteristics of the fluorescent powder for white LED under temperature-variable conditions by using an integrating sphere.

However, the above-mentioned measuring apparatus and method can only measure the overall light emission characteristics of the phosphor, and lacks the evaluation of the spatial light emission characteristics of the phosphor on a micron scale (the phosphor particles are on a micron scale). The micron space luminescence characteristics of the phosphor are important for evaluating and guiding the improvement of the phosphor performance.

Disclosure of Invention

The invention aims to solve the problem that the fluorescent powder in the prior art is lack of measurement of the luminescent characteristic in the micrometer scale space, provides a hyperspectral transmission type testing device and method for the luminescent characteristic of the fluorescent powder, and can accurately obtain luminescent images of the fluorescent powder at the pixel level and obtain spectral data on corresponding pixel points, so that the luminescent characteristic of the fluorescent powder in the micrometer scale space is accurately obtained.

In order to achieve the purpose, the invention adopts the following technical scheme:

the hyperspectral-based transmission-type testing device for the luminous property of the fluorescent powder comprises an LED excitation light source, a fluorescent powder sheet, a three-dimensional control platform, a constant current source, a temperature control module, a microscope, a hyperspectral meter and a computer;

the LED excitation light source is arranged on the three-dimensional control platform, and the three-dimensional control platform is used for adjusting the position of the LED excitation light source;

the constant current source is connected with the LED excitation light source and is used for providing constant current to drive the LED excitation light source;

the temperature control module is arranged on the three-dimensional control platform and is positioned at the bottom of the LED excitation light source, and the temperature control module is used for controlling the temperature of the LED excitation light source;

the fluorescent powder sheet is arranged right above the LED excitation light source;

the microscope is arranged above the fluorescent powder sheet and is used for transmitting the emission light of the fluorescent powder sheet and the excitation light of the LED excitation light source;

the hyperspectral meter is arranged above the microscope and used for collecting and processing light transmitted by the microscope and obtaining hyperspectral data;

the computer is connected with the hyperspectral spectrometer and used for calculating the received hyperspectral data to obtain the parameters of the two-dimensional geometric space, such as the phosphor conversion efficiency, the phosphor quantum efficiency and the like.

The LED excitation light source is arranged at the bottom of the reflection cup, and the fluorescent powder sheet is arranged at the top of the reflection cup.

The fluorescent powder sheet is prepared by uniformly spin-coating a mixture of fluorescent powder and silica gel on a transparent substrate by a spin coater, and curing at high temperature (generally higher than 100 ℃). The transparent substrate is made of materials such as a acrylic Plate (PMMA), transparent quartz glass and a transparent PC plate. The phosphor flakes may be phosphor-in-glass (phos-glass) or phosphor ceramic.

The phosphor in the invention comprises aluminate, borate, nitride, oxide, oxynitride, silicate, phosphate, sulfate or tungstate, etc., and can also be other fluorescence conversion materials, such as quantum dot materials, including perovskite, cadmium stannide or copper indium sulfide, etc.

The LED excitation light source comprises a blue or near-ultraviolet LED excitation light source, and the LED material is mainly a III-V nitride system represented by GaN.

The invention relates to a hyperspectral-based transmission-type test method for the luminescent property of fluorescent powder, which comprises the following steps:

1) placing an LED excitation light source on a temperature control module, setting the temperature of the temperature control module to be T, placing a transparent substrate right above the LED excitation light source, connecting the LED excitation light source with a constant current source, and setting a driving current to be I;

2) moving the three-dimensional control table, adjusting the transparent substrate to be under a microscope, enabling light emitted by the LED excitation light source to penetrate through the transparent substrate, entering the hyperspectral spectrometer through the microscope, collecting and processing the corresponding hyperspectral data by the hyperspectral spectrometer and the computer, and measuring to obtain two-dimensional photon number distribution B of the LED excitation light_m×n；

3) Replacing the transparent substrate with a fluorescent powder sheet, and setting the current and temperature conditions same as those in the step 1);

4) moving the three-dimensional control table to enable the position of the fluorescent powder sheet to be the same as that in the step 2), repeating the process in the step 2), and measuring to obtain LED exciting light two-dimensional photon number distribution BB_m×nAnd the number distribution Y of the photons emitted from the phosphor_m×n；

5) And calculating the fluorescent powder conversion efficiency and the fluorescent powder quantum efficiency distribution of the two-dimensional geometric space of the fluorescent powder sheet.

In the step 2), the total number B of the LED exciting light photons with different wavelengths of each pixel is obtained through integral calculation, and the corresponding two-dimensional matrix is marked as B_m×n(where m, n represent the two-dimensional spatial location coordinates of the pixel):

in the step 4), the total number BB of the LED exciting light photons and the total number Y of the light photons emitted by the fluorescent powder of different wavelengths of each pixel are obtained through integral calculation, and the corresponding two-dimensional matrixes are BB_m×nAnd Y_m×n：

In step 5), the calculated phosphor conversion efficiency

And quantum efficiency of phosphor

Is defined as:

wherein (lambda)₁,λ₂) Is the wave band of LED exciting light (lambda)₃,λ₄) The wavelength band in which the phosphor emits light.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the invention is not limited to measuring the overall luminescence characteristic of the fluorescent powder sheet, and can also obtain optical parameters such as pixel level fluorescent Powder Conversion Efficiency (PCE) and fluorescent Powder Quantum Efficiency (PQE) and two-dimensional geometric space distribution thereof, wherein the fluorescent powder Conversion Efficiency and the fluorescent powder quantum Efficiency are two important parameters for evaluating the fluorescent powder performance. The fluorescent powder conversion efficiency and quantum efficiency data on the two-dimensional geometric space can reflect the uniformity of fluorescent powder particle distribution, can also reflect the optical space distribution condition of exciting light from the side surface, and can be used for assisting in guiding the optimal optical design of a light source.

2. The invention can not only carry out micro-morphology characterization, but also test the luminescence property at the same time, thereby judging whether the distribution of the phosphor powder in the prepared phosphor powder sheet is uniform in the colloid, and can also be used for researching the influence of the phosphor powder with different particle sizes on the luminescence property, such as the scattering and absorption of the phosphor powder particles to light.

3. The invention is provided with the temperature control module, and the temperature control module is integrated in the test system, so that the influence of temperature on the pixel-level light-emitting characteristic of the fluorescent powder sheet can be researched.

4. The invention adopts a transmission mode, and is more suitable for the light-emitting process of the LED excited fluorescent powder compared with a reflection mode.

5. The invention provides constant current to drive the LED excitation light source through the temperature control of the temperature control module and the constant current source, so that the LED excitation light source can obtain relatively stable light output.

6. According to the invention, the three-dimensional control console is used for controlling the position of the temperature control module, the LED, the fluorescent powder sheet and the reflecting cup which are combined below the microscope, and hyperspectral images of the fluorescent powder sheet at different positions can be conveniently shot by adjusting the three-dimensional control console, so that the micron-scale light emitting condition of the fluorescent powder sheet at different spatial positions can be obtained.

Drawings

FIG. 1 is a schematic diagram of the apparatus of the present invention;

FIG. 2 shows two-dimensional distributions of the quantum efficiencies of three different phosphor flakes in the example.

Reference numerals: the device comprises a high-speed spectrometer 1, a microscope 2, a fluorescent powder sheet 3, a reflecting cup 4, a constant current source 5, a three-dimensional control platform 6, a temperature control module 7, an LED excitation light source 8, a transparent substrate 9 and a computer 10.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

As shown in fig. 1, the embodiment of the present invention includes an LED excitation light source 8, a fluorescent powder sheet 3, a reflective cup 4, a three-dimensional console 6, a constant current source 5, a temperature control module 7, a microscope 2, a high-speed spectrometer 1, and a computer 10;

the LED excitation light source 8 is arranged at the bottom of the reflection cup 4, the reflection cup 4 is arranged on the three-dimensional control platform 6, and the three-dimensional control platform 6 is used for adjusting the position of the LED excitation light source 8;

the constant current source 5 is connected with the LED excitation light source 8, and the constant current source 5 is used for providing constant current to drive the LED excitation light source 8;

the temperature control module 7 is arranged on the three-dimensional control platform 6 and is positioned at the bottom of the LED excitation light source 8, and the temperature control module 7 is used for controlling the temperature of the LED excitation light source 8;

the fluorescent powder sheet 3 is arranged on the top of the reflecting cup 4, namely right above the LED excitation light source 8;

the microscope 2 is arranged above the fluorescent powder sheet 3, and the microscope 2 is used for transmitting the emission light of the fluorescent powder sheet 3 and the excitation light of the LED excitation light source 8;

the hyperspectral meter 1 is arranged above the microscope 2, and the hyperspectral meter 1 is used for collecting and processing light transmitted by the microscope 2 and obtaining hyperspectral data;

the computer 10 is connected with the hyperspectral spectrometer 1, and the computer 10 is used for calculating the received hyperspectral data to obtain the parameters of the two-dimensional geometric space, such as the phosphor conversion efficiency, the phosphor quantum efficiency and the like.

In this embodiment, the LED excitation light source 8 is a blue LED excitation light source, the transparent substrate 9 is a transparent PMMA substrate, and the phosphor sheet 3 is a yellow YAG phosphor sheet.

By adopting the device, the hyperspectral transmission-type test method for the luminescent property of the fluorescent powder comprises the following steps:

1) placing an LED excitation light source 8 on a temperature control module 7, setting the temperature of the temperature control module 7 to be T, placing a transparent substrate 9 which is not coated with fluorescent powder right above the LED excitation light source 8, connecting the LED excitation light source 8 with a constant current source 5, and setting a driving current to be I;

2) moving the three-dimensional control table 6, adjusting the transparent substrate 9 under the microscope 2, allowing light emitted by the LED excitation light source 8 to penetrate through the transparent substrate 9, entering the hyperspectral spectrometer 1 through the microscope 2, collecting and processing the hyperspectral spectrometer 1 and the computer 10 to obtain corresponding hyperspectral data, and measuring to obtain two-dimensional photon number distribution B of the LED excitation light_m×n；

3) Replacing the transparent substrate 9 with the fluorescent powder sheet 3, and setting the current and temperature conditions same as those in the step 1);

4) moving the three-dimensional control platform 6 to enable the position of the fluorescent powder sheet 3 to be the same as that in the step 2) (accurately aligning by selecting some characteristic points), repeating the process in the step 2), collecting hyperspectral images and spectral data, obtaining the photon number sum (BB) of the LED exciting light of each pixel and the photon number sum (Y) of the fluorescent powder emitting light of the pixel at the moment through integral calculation, and respectively recording the two-dimensional photon number sums corresponding to the two-dimensional matrix as two-dimensional photon number scoresFabric BB_m×nAnd the number distribution Y of the photons emitted from the phosphor_m×n；

5) Since the data collected by the hyperspectrum is the number of photons, and the quantum efficiency of the phosphor is defined as the ratio of the number of photons emitted by the phosphor to the number of photons of the excitation light of the LED in the portion for conversion, the phosphor conversion efficiency and the distribution of the phosphor quantum efficiency in the two-dimensional geometric space of the phosphor sheet 3 can be calculated by the equations (1) and (2), as shown in fig. 2.

In the embodiment of the invention, the preparation method of the fluorescent powder sheet comprises the following steps:

firstly, uniformly mixing a fluorescent powder and silica gel mixture according to a certain mass ratio, removing bubbles under a vacuum condition, uniformly spin-coating a certain amount of fluorescent powder and silica gel mixture on a transparent substrate (PMMA) by a spin coating instrument according to a set rotating speed, and finally curing under a high-temperature condition (generally higher than 100 ℃, such as 150 ℃).

Preparing three different fluorescent powder tablets by the method, wherein the conditions are that (a) the rotating speed of a spin coater is 700r/min, and the mass ratio of the fluorescent powder to the silica gel is 1: 1; (b) the rotating speed of the spin coater is 700r/min, and the mass ratio of the fluorescent powder to the silica gel is 2: 3; (c) the rotating speed of the spin coater is 900r/min, and the mass ratio of the fluorescent powder to the silica gel is 2: 3.

Referring to fig. 2, it is found by comparing the two-dimensional phosphor quantum efficiencies of different phosphor patches that the ratio of phosphor to silica gel has a significantly greater influence on the phosphor quantum efficiency than the rotation speed. The device and the method can clearly obtain the condition of the luminous uniformity distribution of the fluorescent powder by combining calculation.