CN203155488U - Full-automatic fluorescent powder coating equipment - Google Patents

Abstract

The utility model relates to a fully automatic fluorescent powder coating equipment. The equipment includes a lower computer system and an upper computer system. The lower computer system includes a fluorescent powder nozzle, an xyz axis motion control platform, a fully automatic loading/unloading device and a machine vision device. The upper computer system includes a coating control module, a motion control module and a machine vision control module; it is characterized in that the lower computer system also includes a nozzle constant temperature control device, a vacuum stirring and defoaming device and a laser thickness measuring device; Bubble control module; the coating control module is respectively connected to the phosphor nozzle and the nozzle constant temperature control device, the defoaming control module is connected to the vacuum stirring and defoaming device, the machine vision control module is respectively connected to the laser thickness measuring device and the machine vision device, and the motion control module is connected to the Xyz axis motion control platform and fully automatic loading/unloading device. The utility model greatly improves the phosphor coating accuracy of the phosphor coating equipment on high-power white LED chips or chip modules, thereby effectively improving the thermal resistance dispersion, chromaticity consistency, light output efficiency and other packaging quality of white LED packaging.

Description

A fully automatic fluorescent powder coating equipment

technical field

The utility model relates to the technical field of fluorescent powder coating, in particular to a fully automatic fluorescent powder coating equipment.

Background technique

 White LED is a new type of semiconductor all-solid-state lighting source. Compared with traditional lighting technology, this new type of light source has leading advantages such as high efficiency and energy saving, long life, small size, easy maintenance, green environmental protection, safe use, and good weather resistance. It is recognized as the first choice for future lighting sources.

White LED packaging is a key process to promote the rapid development of international semiconductor lighting and display, while phosphor coating is currently the mainstream technology for realizing the conversion from blue LED to white LED in the world. The core technology and equipment have been monopolized by foreign countries, which directly restricts the emerging LED industry in my country. Sustained development of strategic industries. At present, the traditional phosphor coating equipment made in China generally has the disadvantages of uneven coating thickness, low production capacity, and narrow adaptability. Therefore, independently developed a phosphor coating equipment with high production capacity, high coating precision, and can adapt to the ever-changing development of high-power white LED module packaging technology, getting rid of foreign technology monopoly, has become my country's LED packaging industry chain The only way to develop. This patent proposes a new type of LED phosphor coating process and equipment, based on existing phosphor coating equipment (for example: Tengsheng SD950 online jet dispensing machine, Anda TF-550B coating machine, etc.), including On the basis of existing structures such as phosphor nozzle, xyz axis motion control platform, automatic loading/unloading device and machine vision device, a vacuum stirring and defoaming device is added to simplify the existing coating process and effectively remove phosphor glue The tiny air bubbles contained after mixing; the constant temperature control device of the nozzle is added to control the constant temperature of the phosphor nozzle to achieve the purpose of reducing and stabilizing the viscosity of the phosphor powder in the phosphor nozzle; the laser thickness measuring device is added to use laser The triangulation method is used to measure the thickness distribution of the coated phosphor layer; and a set of phosphor coating learning algorithms is proposed to improve the accuracy of LED phosphor coating. These utility models can effectively improve the packaging quality of white LED packaging such as thermal resistance dispersion, chromaticity consistency, and light output efficiency, and apply related controller design methods and detection algorithm theories to the independent development of automatic phosphor coating equipment to promote Technological innovation of my country's LED packaging and testing industry.

Utility model content

The purpose of this utility model is to provide a fully automatic fluorescent powder coating equipment, on the basis of the existing fluorescent powder coating equipment (for example: Tengsheng SD950 online jet dispensing machine, Anda TF-550B coating machine, etc.) , a vacuum stirring and defoaming device is added to simplify the existing coating process, and the tiny air bubbles contained in the mixed phosphor powder and glue are effectively removed; a constant temperature control device for the nozzle is added to control the temperature of the phosphor nozzle to achieve reduction and stability. The purpose of the phosphor adhesive viscosity in the phosphor nozzle is described; the laser thickness measuring device is added to use laser triangulation to measure the thickness distribution of the coated phosphor layer; and a set of phosphor coating learning algorithms is proposed for Improve the coating accuracy of LED phosphor powder. It can effectively improve the consistency of phosphor powder coating amount and coating thickness, and improve the light source quality and yield of white light LEDs. The purpose of this utility model is achieved through the following technical solutions.

A fully automatic phosphor powder coating equipment, used to complete the phosphor powder coating process on LED chips, the equipment includes a lower computer system and an upper computer system, the lower computer system includes a fluorescent powder nozzle, an xyz axis motion control platform, a fully automatic Loading/unloading device and machine vision device; the upper computer system includes a coating control module, a motion control module and a machine vision control module; it is characterized in that the lower computer system also includes a nozzle constant temperature control device, a vacuum stirring and defoaming device and a laser measuring device. Thickness device; the upper computer system also includes a defoaming control module; the coating control module is connected to the phosphor nozzle and the constant temperature control device of the nozzle, the defoaming control module is connected to the vacuum stirring and defoaming device, and the machine vision control module is connected to the laser thickness measuring device and The machine vision device and the motion control module are respectively connected to the xyz axis motion control platform and the automatic loading/unloading device. the

In the above-mentioned automatic phosphor coating equipment, the phosphor nozzle can use a dispensing nozzle, an atomizing nozzle or a piezoelectric nozzle phosphor nozzle for spraying phosphor glue;

The nozzle constant temperature control device includes a heating wire and a thermistor, and the heating wire and the thermistor are installed inside or outside the phosphor nozzle for constant temperature control of the phosphor nozzle;

The vacuum stirring and defoaming device includes: a phosphor glue container for storing the phosphor glue to be coated; an electric stirring rod for stirring the phosphor glue; an air valve for extracting the air in the phosphor glue container, The air in the phosphor glue container to be coated with phosphor glue is drawn out through the air valve to form a vacuum environment. In the vacuum environment, the electric stirring rod is continuously stirred to stir the bubbles of the phosphor glue in the device from the bottom of the device to Phosphor glue surface is finally eliminated;

The laser thickness measuring device includes: a laser emitter for emitting measuring laser light; a photosensitive surface of the sensor for receiving the measuring laser light reflected back from the measured surface; a lens for converging the measuring laser light emitted by the laser emitter; The laser thickness measuring device is used to measure the thickness distribution of the coated phosphor layer by using laser triangulation;

The machine vision device includes an image sensor, and the image sensor adopts a CMOS sensor or a CCD sensor; the visual processing and control module is based on FPGA, CPLD, DSP, DSP+FPFA or DSP+CPLD; the interface module adopts a bus-based mode, including IEEE 1394a, USB or Ethernet for machine vision positioning of LED brackets and defect detection of phosphor layers after coating;

The xyz axis motion control platform of the nozzle adopts stepper motor, servo motor or linear motor, which is used to control the high-speed and high-precision movement of the phosphor nozzle in the direction of xyz axis;

The fully automatic loading and unloading device includes a loading box and an unloading box, which are used to respectively store the LED brackets to be coated and the LED brackets that have been coated; Bracket delivery work, including sending the LED bracket into the area to be coated in the upper box before coating, and transporting the coated LED bracket to the lower box after coating. The mechanical transfer device adopts a mechanical arm or a conveyor belt accomplish.

In the above-mentioned automatic phosphor coating equipment, the upper computer system includes:

The coating control module realizes the precise control of phosphor glue spraying amount, phosphor atomization control, and flow rate control of phosphor glue inside the phosphor nozzle, which is the key to realize the precise control of phosphor glue spraying amount and phosphor coating uniformity control The control module is used to control the amount of phosphor powder sprayed during the coating process of the phosphor nozzle, the uniformity of atomization, the spraying range and the constant temperature control device of the nozzle to control the heating and constant temperature of the phosphor nozzle to reduce and stabilize the phosphor glue inside the nozzle. viscosity;

The motion control module is used to control the xyz axis motion control device to move the fluorescent powder nozzle in the xyz axis, and is used for coordinated control of the xyz axis motion control device and the automatic loading and unloading device;

Control the vacuum stirring and defoaming device to perform defoaming work, which is used to control the vacuum stirring and defoaming device to perform the defoaming process on the newly mixed phosphor glue;

The machine vision control module controls the laser thickness measuring device and the machine vision device to perform thickness measurement and defect detection of the phosphor layer, and is used to control the laser thickness measurement device to perform laser thickness measurement on the coated phosphor layer, and control The machine vision and defect detection device performs defect detection on the sprayed phosphor layer.

Use the coating process of above-mentioned automatic fluorescent powder coating equipment, it comprises the following steps:

4.1 Use a vacuum stirring and defoaming device to eliminate the bubbles inside the phosphor glue that has just been mixed in the device, and at the same time, heat the phosphor nozzle to the working temperature through the nozzle constant temperature control device;

4.2 After step 4.1 is completed, the LED bracket to be coated is transported to the coating work area through a fully automatic loading and unloading device;

4.3 After step 4.2 is completed, the machine vision module controls the machine vision device to locate the LED bracket to be coated, and obtain the position coordinates of the LED bracket to be coated on the workbench;

4.4 After step 4.3 is completed, move the phosphor spray head directly above the LED bracket to be coated through the xyz axis motion control device;

4.5 After step 4.4 is completed, if it is the first coating of the current type of LED bracket to be coated, use the initial coating control parameters corresponding to the current type of LED bracket to be coated to carry out the first phosphor coating of the current LED bracket to be coated If it is not the first coating of the current LED bracket type to be coated, use the LED bracket phosphor coating thickness distribution parameters measured in step 4.7 after the last coating is completed and correspond to the current LED bracket type to be coated. Initial control parameters, using phosphor coating iterative learning control algorithm to calculate the coating control parameters of the LED bracket to be coated this time;

4.6 Use the current coating control parameters calculated in step 4.5 to control the phosphor nozzle to complete the phosphor coating of the current LED bracket;

4.7 After step 4.6 is completed, the thickness distribution of the phosphor layer of the currently coated LED bracket is detected by the method of obtaining the thickness distribution of the phosphor coating based on the laser triangulation method, which is used for the phosphor coating learning control of step 4.5 In the iterative calculation of the algorithm, the next coating accuracy is calculated;

4.8 After step 4.7 is completed, detect the coating defect information of the phosphor layer through machine vision and defect detection devices;

4.9 Judging whether the coating is completed, if not, go to step 4.2; if finished, end.

In the above-mentioned coating process, the iterative learning control algorithm includes the following steps:

5.1 According to the type of LED bracket to be coated and the set coating thickness, select the initial control parameters of the current type of LED bracket to be coated, including: initial control parameters of phosphor spray time, initial control parameters of phosphor glue atomization, phosphor glue initial flow rate control parameters;

5.2 According to the thickness distribution of the last phosphor layer measured in step 4.7 and the set coating thickness in step 5.1, calculate the coating error of the last phosphor coating;

5.3 According to the coating error obtained in step 5.2, use the iterative learning control algorithm to calculate the correction amount of each control parameter of the current coating controller, including: phosphor powder spraying time control parameter correction amount, phosphor powder glue atomization control parameter Correction amount, phosphor glue flow rate parameter correction amount;

5.4 From the current theoretical control parameters and control parameter corrections obtained in steps 5.1 and 5.3, calculate the actual control value of the current coating controller;

In the above-mentioned coating process, the method for obtaining phosphor coating thickness distribution based on laser triangulation method comprises the following steps:

6.1 Turn on the laser thickness measuring device, and the laser emitter irradiates the surface to be tested, which are the surface of the high-power LED chip before phosphor powder coating and the phosphor powder coated surface after phosphor powder coating;

6.2 Filter the two laser spot images collected in step 6.1 with a smoothing filter;

6.3 Perform binary segmentation on the spot image obtained after filtering in step 6.2; based on the gray histogram of the image, obtain the segmentation threshold through iterative calculation;

6.4 Calculate the position of the center of mass of the laser spot;

6.5 Calculate the phosphor coating thickness distribution by laser triangulation method. the

Compared with the prior art, the utility model has the following advantages and technical effects: the proposed method of the utility model can be applied to the phosphor coating and packaging process of high-power white LED or LED chip modules, and can also Applied in wafer-level chip coating, it can precisely control the coating amount and coating thickness of coating glue with various viscosities, and ensure the consistency of coating thickness. On the basis of traditional full-automatic fluorescent powder coating equipment, the utility model integrates a spray head constant temperature control device, a laser thickness measuring device and a fluorescent powder glue vacuum stirring and defoaming module in the coating equipment, thereby simplifying the fluorescent powder coating process At the same time, the phosphor coating accuracy is improved.

Description of drawings

Figure 1 is a schematic diagram of phosphor coating equipment in the embodiment.

Figure 2 is a block diagram of the system structure of the phosphor coating equipment in the embodiment.

Fig. 3 is a process flow diagram of phosphor coating equipment in an embodiment.

Fig. 4 is a schematic diagram of a phosphor spray head constant temperature control device in an embodiment.

Fig. 5 is a schematic diagram of an optical path for laser measurement thickness distribution detection in an embodiment.

Fig. 6 is a schematic diagram of a vacuum stirring and defoaming device in an embodiment.

Detailed ways

The above content has fully explained the utility model. In order to have a clearer understanding of the technical characteristics, purpose and effect of the utility model, the specific implementation of the utility model is now described in detail with reference to the accompanying drawings.

The fluorescent powder coating lower computer system described in the utility model is shown in Fig. 1 and Fig. 2, and the lower computer system includes: fluorescent powder spray head 12, spray head constant temperature control device 13, spray head xyz axis motion control device 14, the whole Automatic loading and unloading device 15, vacuum stirring and defoaming device 16, laser thickness measuring device 17, machine vision and defect detection device 18. The phosphor coating equipment control module, that is, the upper computer system 11 includes: a coating control module 19 , a motion control module 20 , a vacuum stirring and defoaming control module 21 , and a machine vision control module 22 .

Wherein, the phosphor nozzle 12 can use a dispensing nozzle, an atomizing nozzle or a piezoelectric nozzle phosphor nozzle for spraying phosphor glue;

The nozzle constant temperature control device 13 includes a heating wire and a thermistor, and the heating wire and the thermistor are installed inside or outside the phosphor nozzle for constant temperature control of the phosphor nozzle;

The nozzle xyz axis motion control platform 14 can use a stepper motor, a servo motor or a linear motor to control the high-speed and high-precision movement of the phosphor nozzle in the xyz axis direction;

Fully automatic loading and unloading device 15, including a loading box and an unloading box, which are used to store the LED brackets to be coated and the LED brackets that have been coated; The delivery of the bracket can be realized by using a robot arm or a conveyor belt; it is used to send the LED bracket into the area to be coated in the upper box before coating, and transport the coated LED bracket to the lower box after coating .

Vacuum stirring and defoaming device 16 includes a phosphor glue container for storing the phosphor glue to be coated; an electric stirring rod for stirring the phosphor glue; an air valve for extracting the air in the phosphor glue container; The air valve draws out the air inside the phosphor glue container containing the phosphor glue to be coated to form a vacuum environment. In the vacuum environment, the electric stirring rod is continuously stirred to stir the bubbles of the phosphor glue in the device from the bottom of the device to the phosphor. The surface of powder glue is finally eliminated;

The laser thickness measuring device 17 includes a laser emitter for emitting measuring laser light; the photosensitive surface of the sensor is used for receiving the measuring laser light reflected back from the measured surface; a lens is used for converging the measuring laser light emitted by the laser emitter; Laser thickness measuring device, using laser triangulation method, for measuring the thickness distribution of the coated phosphor layer;

The machine vision device 18 includes an image sensor, adopts a CMOS sensor or a CCD sensor, the visual processing and control module is based on FPGA, CPLD, DSP, DSP+FPFA or DSP+CPLD, and the interface module adopts a bus-based method, including IEEE 1394a, USB or Ethernet for machine vision positioning of LED brackets and defect detection of phosphor layers after coating;

The phosphor coating host computer system 11 described in this utility model is shown in Figure 2, including:

The coating control module 19 realizes accurate control of phosphor glue spraying amount, phosphor atomization control, and flow rate control of phosphor glue inside the phosphor nozzle, and is the basis for realizing precise control of phosphor glue spraying amount and uniformity control of phosphor powder coating key control module. It is used to control the spraying amount of phosphor powder, the uniformity of atomization, the precise control of the spraying range during the coating process of the phosphor nozzle, and control the constant temperature control device of the nozzle to heat the phosphor nozzle to reduce the viscosity of the phosphor slurry inside the nozzle;

The motion control module 20 is used to control the xyz axis motion control device to move the phosphor spray head in the xyz axis with high speed and high precision. It is used for high-precision coordinated control of xyz axis motion control device and fully automatic loading and unloading device;

The vacuum stirring and defoaming control module 21 controls the vacuum stirring and defoaming device to perform defoaming. It is used to control the vacuum stirring and defoaming device to perform the defoaming process on the newly mixed phosphor glue;

The machine vision control module 22 controls the laser thickness measuring device and the machine vision device to perform thickness measurement and defect detection of the phosphor layer. It is used to control the laser thickness measuring device to perform laser thickness measurement on the coated phosphor layer, and to control the machine vision and defect detection device to perform defect detection on the sprayed phosphor layer.

As shown in Figure 3, the fully automatic phosphor coating process includes the following steps:

Step 31, use a vacuum stirring and defoaming device to eliminate the bubbles inside the phosphor glue that has just been mixed in the device, and at the same time, step 32, heat the phosphor nozzle to the working temperature through the nozzle constant temperature control device;

Step 33, transport the LED bracket to be coated to the coating work area through a fully automatic loading and unloading device;

Step 34, after step 33 is completed, control the machine vision device through the machine vision module to locate the LED bracket to be coated, and obtain the position coordinates of the LED bracket to be coated on the workbench;

Step 35, using the xyz axis motion control device to move the phosphor spray head directly above the LED bracket to be coated;

Step 40, after step 35 is completed, if it is the first coating of the current type of LED bracket to be coated, use the initial coating control parameters corresponding to the current type of LED bracket to be coated to perform the first fluorescence of the current LED bracket to be coated powder coating; if it is not the first coating of the current LED bracket type to be coated, then use the LED bracket phosphor coating thickness distribution parameters measured in step 38 after the last coating is completed to be the same as the current LED bracket type to be coated. For the corresponding initial control parameters, use the iterative learning control algorithm for phosphor coating to calculate the coating control parameters of the LED bracket to be coated this time.

Step 36, using the current coating control parameters calculated in step 40 to control the phosphor spray head to complete the phosphor coating work of the current LED bracket;

Step 37, after step 36 is completed, the thickness distribution of the phosphor layer of the currently coated LED bracket is detected by the method of obtaining the thickness distribution of the phosphor coating based on the laser triangulation method, which is used for the phosphor coating of step 36 In the iterative calculation of the learning control algorithm, the next coating accuracy is calculated.

Step 38, after step 37 is completed, the coating defect information of the phosphor layer is detected by machine vision and defect detection device;

Step 39, judging whether the coating is completed, if not, go to step 40; if finished, go to step 41.

Step 41 , move the coated LED bracket to the unloading rack through the unloading mechanism.

The above iterative learning control algorithm includes the following steps:

(1) According to the type of LED bracket to be coated and the set coating thickness, select the initial control parameters of the current type of LED bracket to be coated, including: initial control parameters of phosphor powder spraying time, initial control parameters of phosphor powder glue atomization, fluorescence Initial control parameters of powder and rubber flow rate;

(2) Calculate the coating error of the last phosphor coating according to the phosphor coating thickness distribution of the last coating obtained based on the laser triangulation method and the set coating thickness in step (1);

(3) According to the coating error obtained in step (2), use the iterative learning control algorithm to calculate the correction amount of each control parameter of the current coating controller, including: phosphor powder spraying time control parameter correction amount, phosphor powder glue Atomization control parameter correction amount, phosphor glue flow rate parameter correction amount;

(4) From the current theoretical control parameters and control parameter corrections obtained in steps (1) and (3), calculate the actual control value of the current coating controller;

The method for obtaining the phosphor coating thickness distribution based on the laser triangulation method includes the following steps:

(1) Turn on the laser ranging sensor and irradiate the surface to be measured, which are the surface of the high-power LED chip before phosphor powder coating and the phosphor powder coated surface after phosphor powder coating;

(2) Filter the two laser spot images collected in step (1) with a smoothing filter;

(3) Binary segmentation is performed on the spot image obtained after filtering in step (2); based on the gray histogram of the image, the segmentation threshold is obtained through iterative calculation;

(4) Calculate the position of the center of mass of the laser spot;

(5) The laser triangulation method is used to calculate the thickness distribution of the phosphor coating.

The above-mentioned laser ranging sensor is used to emit laser light for measuring the thickness distribution of phosphor powder coating.

As an example, a fully automatic phosphor coating process, as shown in Figure 3, includes the following steps:

The implementation method of process 31 is as follows: first mix the epoxy resin glue with the fluorescent powder, the specific gravity of the mixed colloid is 1.60-1.80g/cm3, and the viscosity is 4000-5500 Pa·s; as shown in Figure 6, the mixed colloid Pass the phosphor glue into the phosphor glue inlet 51, open the valve V-3, so that the phosphor glue enters the vacuum stirring and defoaming device 16, open the valve V-1 and use the gas channel 53 to extract the air in the phosphor glue container 54 Form a vacuum, turn on the stirring motor 56 to rotate the stirring rod 55, and carry out vacuum defoaming treatment. After the process of defoaming is completed, then open the valve V-2 of the phosphor glue, and the phosphor glue after defoaming flows in from the outlet channel 52 Phosphor powder nozzle 12 miles.

Please refer to FIG. 3 , the implementation method of process 32 is as follows: as shown in FIG. 4 , the phosphor nozzle 12 is heated to the working temperature through the constant temperature control device 13 , and the phosphor glue after mixing and defoaming flows into the phosphor nozzle 12 After the phosphor powder is glued into the channel, the coating control module 19 in the phosphor coating equipment control module uses the PID control (proportional integral differential control) method to control the nozzle constant temperature control device 13 to heat the phosphor nozzle 12, and wait for the phosphor nozzle to stabilize When it is near the set working temperature T. Generally, the working temperature can be set according to different viscosities of the phosphor glue, where the viscosity of the phosphor glue is roughly inversely proportional to the working temperature.

Please refer to Fig. 3, the implementation method of operation 33 is as follows: the fully automatic loading and unloading device 15 moves and fixes the LED chip support group to be coated in the feeding trough 9 on the workbench of the motion control device 14; Zero coordinates are set in the computer system 11. The fully automatic loading and unloading device can use a mechanical arm to grab or a conveyor belt delivery device to transport the LED bracket to complete the loading work.

Please refer to Fig. 3, the implementation method of operation 34 is as follows: the machine vision and defect detection device 18 carries out the machine vision positioning work to the LED bracket to be coated fixed on the workbench, and by calculating the gray scale of the image, locates the LED bracket to be coated currently The precise position of the covered LED chips.

Please refer to FIG. 3 , the implementation method of process 35 is as follows: the spray head 12 is accurately moved to the coating area through the xyz axis motion control device 14, and various dimensional information and various movements of the LED bracket to be coated are input into the host computer system 11 Control the coating parameters, including the distribution of the LED chip array, the distance between the LED chips, the coating route of the nozzle, and the moving speed of the nozzle; after the LED chip bracket group is placed and fixed on the workbench of the motion control device, the upper computer The system 11 moves the phosphor spray head 12 over the LED chip to be coated with high speed and high precision according to the input parameter information. The vertical distance between the nozzle and the LED chip depends on the size of the LED chip.

Please refer to FIG. 3 , the implementation method of the process 36 is as follows: the control parameters of the current phosphor nozzle 12 are calculated by the coating control module 19 in the host computer system 11 , and the coating is performed this time. The specific algorithm is as follows:

A phosphor coating learning control algorithm, including the following:

According to the target coating thickness, the coating controller calculates the current control parameters for the coating control device module, including: phosphor powder spraying time theory control parameters, phosphor powder glue atomization theory control parameters, phosphor glue flow rate theory Parameter vector of control parameters. Among them, the spraying time control parameters can be obtained by calculating the amount of phosphor powder sprayed each time, the flow rate of the phosphor glue in the phosphor nozzle, and the diameter of the nozzle; the phosphor atomization air pressure control parameters can be determined by the size of the LED chip, the phosphor nozzle The flow rate of the inner phosphor glue and the distance between the nozzle and the surface of the LED chip are calculated; the flow rate control parameters of the phosphor glue are calculated comprehensively based on the spraying time control parameters and the phosphor atomization air pressure control parameters.

Calculate the last coating error according to the thickness of the phosphor layer measured last time and the target coating thickness; according to the coating error obtained in the previous step, use the iterative learning control algorithm to calculate the current coating control The correction amount of the control parameters of the device module, including: the correction amount of the spraying time control parameter, the correction amount of the phosphor atomization control parameter, and the correction amount of the phosphor glue flow rate control parameter;

The above iterative learning algorithm can use different learning operators, and the goal is to improve the thickness accuracy of the phosphor coating. For example, using a "PID-type" iterative learning algorithm as follows:

为理论控制参数向量，包括：喷涂时间控制理论控制参数、荧光粉雾化控制理论控制参数和荧光粉胶流速控制理论控制参数；

为当前涂覆控制器的真实控制参数向量；

为上一次荧光粉涂层的厚度误差向量；

、、

为常数增益矩阵。 in, for time,

is the theoretical control parameter vector, including: spraying time control theoretical control parameters, phosphor atomization control theoretical control parameters and phosphor glue flow rate control theoretical control parameters;

is the real control parameter vector of the current coating controller;

is the thickness error vector of the last phosphor coating;

, ,

is a constant gain matrix.

The actual control parameter vector of the current coating controller is calculated from the current theoretical control parameter and the correction amount of the control parameter obtained in the above steps; based on the actual control amount, the phosphor nozzle is controlled to perform the coating work.

Please refer to Fig. 3, the implementation method of process 37 is as follows: the thickness of the fluorescent powder layer is detected by the laser thickness measuring device 17, and the laser thickness measuring device 17 follows the phosphor powder nozzle to move to the top of the LED chip through the motion control device 14. Measure the distance between the laser detection device 17 and the LED chip to be coated before the phosphor powder is coated; wait for the coating to be completed, and then measure the distance between the laser detection device 17 and the upper surface of the phosphor layer The accurate thickness of the phosphor layer can be obtained by subtracting the two obtained distances.

Please refer to FIG. 3 , the implementation method of process 38 is as follows: check out the surface defects of the currently coated phosphor layer through machine vision and defect detection device 18, and follow the phosphor spray head through machine vision and defect detection device 18 through motion control device 14 Move above the LED chip to obtain a high-definition image of the current phosphor coating, divide the phosphor coating in the image into several areas, and then compare the gray distribution map obtained for each area with the corresponding standard uniform coating The phosphor layer is compared to determine whether the current phosphor coating is defective.

The algorithm of the above machine vision control module is as follows:

，荧光粉未涂覆前入射主光线入射到大功率LED芯片表面46的A点上，经透镜成像43后像点落在传感器感光面44的C点。荧光粉的涂覆厚度为H，B点为荧光粉涂覆完成后入射主光线在荧光粉涂覆面45上的入射点，D点为B点在传感器感光面上的像点，C点到D点的距离为

。由三角关系推导可得： As shown in Figure 5, the incident chief ray sent from the laser 1 passes through the converging lens 42 and forms an angle θ with the normal of the measured object surface, and the imaging chief ray forms an angle φ with the normal, and the focal length of the imaging lens 43 is

, before the phosphor powder is not coated, the incident chief ray is incident on point A on the surface 46 of the high-power LED chip, and the image point falls on point C on the photosensitive surface 44 of the sensor after being imaged by the lens 43 . The coating thickness of the phosphor powder is H, point B is the incident point of the incident chief light on the phosphor powder coating surface 45 after the phosphor powder coating is completed, point D is the image point of point B on the photosensitive surface of the sensor, point C to D The point distance is

. Derived from the triangle relation:

The above principle analyzes the thickness measurement principle of a certain point on the laser beam. The thickness measurement of other points can also obtain the thickness according to this principle, and then the thickness distribution map of the phosphor coating can be obtained.

The ROF model can better remove image noise and maintain the edge information of the image. The specific description is as follows:

为含噪图像，

是

的BV半范，C为实数域，参数

为正则化参数。 in, for the original image,

is a noisy image,

yes

The BV seminorm of , C is the field of real numbers, and the parameter

is a regularization parameter.

The collected coating image is denoised and preprocessed using the ROF model above, and then edge detection is performed.

Edge detection is a detection method characterized by local operations, including the method of edge detection operator combined with threshold segmentation, edge detection based on region growth, etc. In the patented algorithm, the region growth method is mainly used to obtain the boundary matrix of the component, and based on the gray histogram of the image, the nearest segmentation threshold is obtained through iterative calculation.

The implementation process of laser thickness measurement, machine vision and defect detection is further detailed below:

(1) Turn on the laser transmitter and irradiate the surface to be tested. The surfaces to be tested are the surface of the high-power LED chip before phosphor powder coating and the phosphor powder coated surface after phosphor powder coating;

(2) Use the image acquisition terminal to collect two laser spot images before and after phosphor coating; using the two laser spot images, use laser triangulation to calculate the thickness distribution of the phosphor coating, and judge whether it is based on the set thickness standard. There are defects of too thick, too thin and uneven thickness;

(3) Turn off the laser transmitter, adjust the angle of the image sensor so that the receiving surface of the image sensor is parallel to the phosphor coating surface, and then use the image acquisition terminal to collect the phosphor coating image after phosphor coating;

(4) Perform filtering and edge detection on the phosphor coating image collected in step (3), then compare it with the standard phosphor coating image template, and finally check whether there is any irregularity on the coating surface of the phosphor coating according to the comparative analysis. Defects from rules, glue and foreign objects.

In step (2), the method for obtaining the phosphor coating thickness distribution based on the laser triangulation method is as follows:

① Filter the collected two laser spot images with a smoothing filter;

② Binary segmentation is performed on the spot image obtained after filtering in step ①; based on the gray histogram of the image, the segmentation threshold is obtained through iterative calculation;

③ Calculate the position of the center of mass of the laser spot;

④Using laser triangulation method to calculate the thickness distribution of phosphor coating.

In step (4), the detection method for the irregularity of the coating surface, glue and foreign matter defects is as follows:

① Establish a standard phosphor coating template;

②Denoise the phosphor coating image collected in the preceding step (3) with the ROF model;

③ Perform deblurring and enhanced preprocessing on the phosphor coating image obtained after denoising in step ②, and make a copy;

④ Perform edge detection on one of the phosphor coating images in step ③, fill the obtained closed phosphor coating surface and calculate the area of the phosphor coating surface, compare it with the set area standard, and judge whether there is Defects that the coating surface is too large or too small;

⑤ Perform pattern matching on the other phosphor coating image in step ③ with the standard phosphor coating template image to determine whether there are defects such as irregular coating, foreign matter, or glue.

Please refer to Figure 3, the implementation method of process 39 is as follows: judge whether the current LED bracket coating work is completed through the host computer system 11. If complete, then go to process 41; if not complete, then go to process 40.

Please refer to Fig. 3, the implementation method of operation 40 is as follows: the coating defect information detected by the thickness of the phosphor layer and the machine vision and defect detection device 18 detected by the laser thickness measuring device 17 is used as the data of the learning algorithm; The computer system 11 then uses these detection information to use an iterative learning algorithm to calculate the control parameters for the next coating.

Please refer to Figure 3, the implementation method of process 41 is as follows: the fully automatic loading and unloading device 15 grabs and moves the coated LED bracket on the workbench of the motion control device 14 to the unloading chute 8.

Claims (3)

1. A fully automatic phosphor coating equipment, used to complete the phosphor coating process on LED chips, the equipment includes a lower computer system and an upper computer system, the lower computer system includes a phosphor nozzle, xyz axis motion control platform, Fully automatic loading/unloading device and machine vision device; the upper computer system includes a coating control module, a motion control module and a machine vision control module; it is characterized in that the lower computer system also includes a nozzle constant temperature control device, a vacuum stirring and defoaming device and Laser thickness measurement device; the host computer system also includes a defoaming control module; the coating control module is connected to the phosphor nozzle and the constant temperature control device of the nozzle, the defoaming control module is connected to the vacuum stirring and defoaming device, and the machine vision control module is connected to the laser thickness measurement device and machine vision device, the motion control module is respectively connected to the xyz axis motion control platform and the automatic loading/unloading device. 2. The fully automatic phosphor coating device according to claim 1, wherein the phosphor nozzle can use a glue dispensing nozzle, an atomizing nozzle or a piezoelectric nozzle phosphor nozzle for spraying phosphor glue; The nozzle constant temperature control device includes a heating wire and a thermistor, and the heating wire and the thermistor are installed inside or outside the phosphor nozzle for constant temperature control of the phosphor nozzle; The vacuum stirring and defoaming device includes: a phosphor glue container for storing the phosphor glue to be coated; an electric stirring rod for stirring the phosphor glue; an air valve for extracting the air in the phosphor glue container, The air in the phosphor glue container to be coated with phosphor glue is drawn out through the air valve to form a vacuum environment. In the vacuum environment, the electric stirring rod is continuously stirred to stir the bubbles of the phosphor glue in the device from the bottom of the device to Phosphor glue surface is finally eliminated; The laser thickness measuring device includes: a laser emitter for emitting measuring laser light; a photosensitive surface of the sensor for receiving the measuring laser light reflected back from the measured surface; a lens for converging the measuring laser light emitted by the laser emitter; The laser thickness measuring device is used to measure the thickness distribution of the coated phosphor layer by using laser triangulation; The machine vision device includes an image sensor, and the image sensor adopts a CMOS sensor or a CCD sensor; the visual processing and control module is based on FPGA, CPLD, DSP, DSP+FPFA or DSP+CPLD; the interface module adopts a bus-based mode, including IEEE 1394a, USB or Ethernet for machine vision positioning of LED brackets and defect detection of phosphor layers after coating; The xyz axis motion control platform of the nozzle adopts stepper motor, servo motor or linear motor, which is used to control the high-speed and high-precision movement of the phosphor nozzle in the direction of xyz axis; The fully automatic loading and unloading device includes a loading box and an unloading box, which are used to respectively store the LED brackets to be coated and the LED brackets that have been coated; Bracket delivery work, including sending the LED bracket into the area to be coated in the upper box before coating, and transporting the coated LED bracket to the lower box after coating. The mechanical transfer device adopts a mechanical arm or a conveyor belt accomplish. 3. The fully automatic phosphor coating equipment according to claim 1, characterized in that the host computer system includes: The coating control module realizes the precise control of phosphor powder spraying amount, phosphor atomization control, and flow rate control of phosphor powder glue inside the phosphor nozzle, which is used to control the phosphor powder spraying amount and atomization uniformity during the phosphor nozzle coating process , the spraying range and control nozzle constant temperature control device controls the heating and constant temperature of the phosphor nozzle to reduce and stabilize the viscosity of the phosphor glue inside the nozzle; The motion control module is used to control the xyz axis motion control device to move the fluorescent powder nozzle in the xyz axis, and is used for coordinated control of the xyz axis motion control device and the automatic loading and unloading device; Control the vacuum stirring and defoaming device to perform defoaming work, which is used to control the vacuum stirring and defoaming device to perform the defoaming process on the newly mixed phosphor glue; The machine vision control module controls the laser thickness measuring device and the machine vision device to perform thickness measurement and defect detection of the phosphor layer, and is used to control the laser thickness measurement device to perform laser thickness measurement on the coated phosphor layer, and control The machine vision and defect detection device performs defect detection on the sprayed phosphor layer.

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