System and method for determining spray characteristics

Abstract

A system and method are provided for determining spray characteristics of a powder or liquid spray. The method includes receiving spray characteristics of a powder or liquid spray, generating a spray map including correlating the received spray characteristics with spray application characteristics, operating parameters of a spray device, or both, wherein the correlation is determined using calibration of scan measurements, and outputting the spray map. In certain cases, the method further includes using the spray map to adjust operating parameters of the spray device to achieve specific performance in spray application.

Description

Technical Field

[0001] The following generally relates to powder or liquid spray devices, and more particularly to systems and methods for determining spray characteristics of powder or liquid sprays.

Background Art

[0002] Spray nozzles have a wide variety of applications, such as spray cooling systems, coating devices, irrigation and pesticide spraying in the agricultural field, and fuel injection systems for most engines. The spray formed by a spray nozzle is characterized by the size and spatial distribution of the droplets, which depend on the shape of the nozzle, the properties of the fluid, and operating settings such as the flow rate and pressure of the fluid. As an example, in automotive painting applications, the film thickness of the paint sprayed on the surface depends on factors such as, for example, the size of the spray droplets, the spray pattern or shape (the number of droplets flying through a unit area per second), the overlap distance, the number of painting passes, and the speed of the robot. Since a thick film thickness can cause defects and (due to the use of more paint) unnecessary additional costs, the tolerance on the film thickness is very strict.

Summary of the Invention

[0003] In one aspect, a processor-executable method for determining spray characteristics of a powder or liquid spray is provided, the method including receiving spray characteristics of the powder or liquid spray and generating a spray map that correlates the received spray characteristics with spray application characteristics, operating parameters of the spray device, or both, wherein the correlation is determined using calibration of scan measurements, and outputting the spray map.

[0004] In certain embodiments of the method, the method further includes adjusting operating parameters of the spray device to achieve a particular performance of the spray application using the spray map.

[0005] In another example of the method, the spray characteristics include one or more of droplet size, droplet distribution, droplet velocity, and spray pattern or shape.

[0006] In yet another example of the method, the operating parameters include one or more of bell speed, flow rate, shaping air flow rate, and electrostatic charge.

[0007] In yet another embodiment of the method, the scan measurements are performed at a plurality of distinct positions.

[0008] In yet another example of the method, the spray device moves radially, and generating the spray map includes determining the spatial position of each droplet as a function of the spray radius using the time at which each acquired scan was performed.

[0009] In yet another example of the method, calibration includes changing one or more operating parameters and determining the effect on the spray characteristics using the scan measurements.

[0010] In yet another example of the method, the spray map is generated using a model that correlates the spray characteristics with the operating parameters.

[0011] In yet another example of the method, generating the spray map includes correlating the spray characteristics with changes in the operating parameters and correlating the changes in the spray characteristics with the spray application characteristics.

[0012] In yet another example of the method, the spray application characteristics include one or more of color, film formation, film appearance and quality, evaporation, powder morphology, and transfer efficiency.

[0013] In another aspect, a system for determining spray characteristics of a powder or liquid spray is provided, the system comprising one or more processors in communication with a data memory, the processors receiving a scan module for receiving spray characteristics of the powder or liquid spray and generating a spray map correlating the received spray characteristics with spray application characteristics, operating parameters of the spray device, or both, determining this correlation using calibration of the scan measurements, and outputting the spray map.

[0014] In a particular instance of the present system, the system further includes an adjustment module that adjusts the operating parameters of the spray device to achieve specific performance of the spray application using the spray map.

[0015] In another instance of the present system, the spray characteristics include one or more of droplet size, droplet distribution, droplet velocity, and spray pattern or shape.

[0016] In yet another instance of the present system, the operating parameters include one or more of bell speed, flow rate, shaping air flow rate, and electrostatic charge.

[0017] In yet another instance of the present system, the scan measurements are performed at a plurality of distinct locations.

[0018] In yet another instance of the present system, the spray device moves radially, and generating the spray map includes determining the spatial position of each droplet as a function of the spray radius using the time at which each acquired scan was performed.

[0019] In yet another instance of the present system, the calibration includes changing one or more operating parameters and determining the effect on the spray characteristics using the scan measurements.

[0020] In yet another instance of the present system, the spray map is generated using a model that correlates the spray characteristics with the operating parameters.

[0021] In yet another example of the system, generating the spray map includes correlating spray characteristics with changes in operating parameters and correlating changes in spray characteristics with spray application characteristics.

[0022] In yet another example of the system, the spray application characteristics include one or more of color, film formation, film appearance and quality, evaporation, powder form, and transfer efficiency.

[0023] These and other aspects are contemplated and described herein. It will be understood that the above summary is illustrative of representative aspects of the systems and methods and is intended to assist the reader, a person skilled in the art, in understanding the forms for carrying out the invention described hereinafter.

[0024] The features of the invention will become more apparent in the forms for carrying out the invention hereinafter, to which reference is made. BRIEF DESCRIPTION OF THE DRAWINGS

[0025]

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Embodiments for Carrying Out the Invention

[0026] Here, embodiments will be described with reference to the drawings. For the sake of concise and clear illustration, the same reference numerals may be repeatedly used between the drawings to indicate corresponding or similar elements when it is judged appropriate. Furthermore, many specific details are shown so that the embodiments described in this specification can be fully understood. However, those skilled in the art will understand that the embodiments described in this specification can be implemented without these specific details. In other examples, detailed descriptions of known methods, procedures, and components are omitted so as not to obscure the embodiments described in this specification. Also, this description should not be construed as limiting the scope of the embodiments described in this specification.

[0027] Throughout the entire form for implementing this invention, various terms used can be interpreted as follows unless the context indicates otherwise. "Or" is used in an inclusive sense and is synonymous with what is described as "and / or". The singular articles and pronouns used throughout include their plurals and vice versa. Similarly, pronouns specifying gender also include the corresponding pronouns of the other gender, and it should not be understood that the use, implementation, performance, etc. of the content described in this specification are limited to a specific gender. The term "exemplary" should be interpreted as "illustrative (for the purpose of explanation)" or "exemplifying", and should not necessarily be interpreted as "preferred" over other embodiments. Further definitions may be described in this specification. These terms may also be applied to the examples before and after the terms as understood by reading the form for implementing this invention.

[0028] Any module, unit, component, server, computer, terminal, engine, or device that executes commands described herein may include a computer-readable medium, such as a storage medium, computer storage medium, or a data storage device (removable and / or non-removable) such as a magnetic disk, optical disk, or tape, or may be accessible to a computer-readable medium. The computer storage medium may include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage devices, magnetic cassettes, magnetic tape, magnetic disk storage devices, or other magnetic storage devices, or any other medium that can be accessed by an application, module, or both and can be used to store desired information. Any such computer storage media may be part of a device or accessible or connectable to a device. Further, unless the context clearly indicates otherwise, the processor or controller described herein may be implemented as a single processor or as multiple processors. The multiple processors may be arrayed or distributed, and any processing function referenced in this specification may be executed by one or more processors even if a single processor is illustrated. Any method, application, or module described herein may be implemented using computer-readable / executable instructions stored on or held by such a computer-readable medium and executable by one or more processors.

[0029] The following generally relates to powder or liquid spray devices, and more particularly to systems and methods for determining spray characteristics of a powder or liquid spray.

[0030] In the present disclosure, although generally referring to the application of spray paint using a spray coating apparatus, it should be understood that the present embodiment can also be used for any suitable powder or liquid spray coating, such as paint, evaporative cooling, or combustion.

[0031] In one application example, the spray of a pharmaceutical product is composed of a liquid consisting of a solid dissolved in a solvent. During the spray drying process, it is ideal for the solvent to evaporate, leaving only spherical and monodisperse hollow porous particles. Particles are formed when the concentration of the solid on the droplet surface reaches a predetermined critical level. Since the size and shape of the particles directly affect the performance of the spray-dried product, it is desirable for the solid to form a spherical shell and maintain its structure. Current methods used to predict droplet size generally lack the ability to capture the viscoelastic behavior of polymer spray solutions used in pharmaceutical applications. Advantageously, by using the embodiments described herein, it is possible to significantly improve production capacity and compound performance by generating a droplet size distribution that results in optimal particle size and shape.

[0032] In a specific example, automotive paint is applied using an electrostatic rotary bell-type atomizer. These utilize centrifugal force to move a thin coating film on the inner surface of the bell cup towards its outer edge, and function by breaking down the paint sheet into a cloud of droplets after it is released. Air jets and electrostatic forces are used to direct the paint towards the target surface. A robot manipulator is used to position the paint atomizer. It may take 3 to 5 months of trial and error to determine which robot motion path will minimize paint, cycle time, and material waste while forming a film with acceptable uniformity. To reduce the costs and time associated with bringing a new vehicle to market, there are also some common efforts to automate the robot motion path by simulating the paint application process.

[0033] The painting factory may be the largest source of regulated chemical substances including VOCs (about 35 g / m2 per painted automobile surface) and other air pollutants (the CO2 equivalent emissions are about 0.5 tons per vehicle). More than 80% of the environmental problems in automobile assembly are related to the painting process. The cost of the exclusion devices for recovering these emissions and treating hazardous waste is very high. Nevertheless, the efficiency of the painting process is extremely poor. The transfer efficiency, that is, the proportion of the sprayed paint that adheres to the surface, is only about 40% for the car body of an automobile and a mere 10% for small parts. By improving the transfer efficiency, it is possible to significantly reduce emissions and energy consumption. Based on these issues, by effectively utilizing the embodiments of the present disclosure, it is possible to reduce VOC emissions, improve transfer efficiency, and minimize the reprocessing of painted parts.

[0034] In some methods, a regression model that correlates a test matrix of operating parameters with the measured film formation may be used to determine the film thickness of the paint sprayed by a spray nozzle. However, this method is both time-consuming and costly. In such cases, the atomizer sprays onto a "scanner" and measures the resulting film formation. This technique has the limitation that, since the spray cannot be directly measured in real time, for example, it may not be possible to grasp the spray characteristics on the production line.

[0035] In another common method, the transfer efficiency of the paint sprayed onto the surface to be sprayed is determined by weighing the sample after spraying and calculating the amount of paint on the surface relative to the amount sprayed. In some cases, a method of increasing the electrostatic charge is adopted to solve this problem, but this may cause a short circuit in the robot, and furthermore, the atomization of the liquid progresses (the momentum required for extremely small droplets to collide with the surface is lost).

[0036] The size of the paint droplets impinging on the surface affects the color of the film and the flop (an indicator of the brightness change at different viewing angles). In some approaches, it is possible to measure the droplet size using a laser-based device that relies on reflection. However, the metal flakes within the rotating paint droplets can disrupt this signal, making it very difficult to accurately measure the size of the paint spray droplets.

[0037] Many process interventions can cause fluctuations in the spray characteristics and potentially damage the sprayed paint film. When attempting to control many process interventions (such as humidity, paint composition, temperature, and downdraft velocity), errors are likely to occur because the uncertainties on each parameter accumulate. In this embodiment, for example, by determining spray characteristics such as the droplet size, spray pattern, or shape, it becomes possible to use accurate control parameters for the spray.

[0038] In some current approaches, they are used to determine whether a particular paint should be sprayed wet (high solvent content in the impinging droplets) or dry (low solvent content) by trial and error on the manufacturing line.

[0039] To measure the particle size distribution, there are various methods using different techniques. For example, methods based on diffraction, phase Doppler methods, direct imaging methods, etc. can be mentioned. However, conventional direct imaging techniques generally only support operation within a research and development environment and do not fully meet the requirements for operation within a hazardous area. Due to their size, the laser system, high-speed camera, and optical system require each of these components to be installed separately within the working environment. Subsequently, the camera and the laser need to be aligned. This alignment is usually a time-consuming process and may need to be frequently re-executed due to the components shifting slightly over time, the possibility of the working position moving, or other devices within the working environment accidentally contacting the measuring equipment.

[0040] Furthermore, generally other methods for measuring particle size do not meet the minimum requirements for operating within a hazardous area and thus cannot function in many industrial environments where sprays are used.

[0041] Furthermore, current droplet measurement technologies generally do not instruct users on how the measured droplet size relates to the final color or coating quality (e.g., in the automotive painting industry), and thus understanding this relationship is left to the user. Additionally, there is no framework or process for users to apply measurement data to solve painting problems.

[0042] In other methods for measuring spray patterns and shapes, devices are used that provide information on how the spray is distributed in space. These approaches generally do not provide information on droplet size. Although these methods may be useful for estimating film thickness, they do not measure droplet size and thus do not provide users with useful information regarding evaporation, color, or the likelihood of surface defects.

[0043] Generally, current methods at least include problems such as non-uniform film thickness, low transfer efficiency, non-uniform color matching between parts, surface defects due to low-quality sprays, and overall increased emissions of volatile organic compounds and greenhouse gases due to errors.

[0044] In some cases, the quality of the spray (e.g., dirty cups, clogged atomization, etc.) can be qualitatively judged by using an image of the liquid ejected from the edge of the cup. This provides a good estimate of the droplet size distribution, but generally does not fully represent the droplet size that actually affects the surface, nor the spray pattern and shape (which are of particular interest in industrial fields), as there may be spatial variations that can affect film formation. Additionally, this method may require dealing with dirty cups, clogged atomization, etc.

[0045] In this embodiment, in the distance from the tip of the spray to the part, an image taken radially across the spray can be used to effectively extract the spray pattern and shape from the taken image. By using the relative frequency of droplets in the image at various radial positions, the pattern or shape of the spray can be obtained, and a flux spray map of the spray can be generated in real time on the production line.

[0046] In some cases, for each paint, a spray map correlating spray characteristics such as droplet size and spray pattern or shape with color and film formation can be determined. By using this spray map, it becomes possible to predict whether the finish and color of the painting are within the allowable range specified by the manufacturer. Furthermore, when the quality of the spray is not sufficient, appropriate corrective measures can be recommended to the painter using this embodiment. Advantageously, these corrective measures can significantly reduce the time required for paint inspection and reduce paint waste and emissions. On the assembly line, for example, spray characteristics such as droplet size and spray pattern or shape can be continuously monitored, so that the painter can confirm that the paint spray is within the specifications. Even if the paint spray does not meet the specifications, preventive maintenance can be carried out before defects occur.

[0047] Through experiments, the inventors have determined that spray characteristics, such as for example droplet size and spray pattern or shape, provide for an accurate characterization of powder or liquid spray coating, such as for example the appearance and quality of the film. Using the spray map and prediction model for film formation of the present embodiment means that the painter does not have to spend excessive time finding the optimal operating parameters for color matching required by the OEM or the spray rate and overlap necessary to match the film thickness. Generally, even if paint manufacturers provide recommended settings for the operating parameters of the atomizer, environmental factors (such as humidity and temperature) can affect the paint and the expected results may not be obtained. Advantageously, based on the spray map, a painter can be notified if the spray characteristics do not match the recommended specifications. This prevents painting from continuing if the coating (such as color) goes out of specification.

[0048] In the present disclosure, while generally referring to applications of spray coating, the determination of spray characteristics is applicable to any suitable application, as would be understood by a person skilled in the art. As a non-limiting example, the present system is applicable to pharmaceutical applications where spray characteristics, such as for example droplet size, directly affect the particle size and can be an important process parameter.

[0049] In automotive painting applications, the paint is solvent-based, with its main components being solvents that evaporate during spraying and the paint film fixing process. The rheology of the colliding droplets determines the paint film formation process on the surface and thereby the color. However, evaporation during droplet transport can be accelerated by electrostatic charges, making it difficult to grasp the rheology of the droplets at the time of collision. One advantage of the present system being described is that it can measure this evaporation rate (which is specific to each paint and affected by environmental conditions). If the droplet size does not fall within a predetermined specification range, feedback is provided to the painter. By constantly being aware of the droplet rheology, the painter can determine whether to spray a particular paint wet (high solvent content in the film) or dry (low solvent content) without trial and error. Furthermore, by ensuring the paint film quality while maintaining the droplet rheology at the time of collision within the specifications, it becomes possible to manufacture solvent-based paints with a lower solvent content. This can reduce the emissions of VOCs, which is one of the limiting parameters in automotive manufacturing.

[0050] Furthermore, by measuring the droplet velocity (one spray characteristic), the operator can grasp the average time required for the droplets to reach the object and thus the evaporation time scale. Figure 18 shows a graph of the experimental results of the cumulative relative volume of a spray containing solids dissolved in a solvent at several axial distances from the nozzle. This volume is normalized by the volume at a distance of 50 mm. In Figure 18, it is clearly shown that evaporation causes the relative volume of the spray to decrease as the distance from the nozzle increases.

[0051] In various current methods, to check the film thickness of a spray coating, an operator needs to spray the sample surface and then measure the film formation using an appropriate measuring device. This is both time-consuming and costly, and only generates measurements at one point. In other current methods, the atomizer sprays the sample onto a "scanner" and measures the resulting film formation. In this embodiment, a much faster method is provided that predicts the film thickness on the surface from an image of the spray, without the need to spray the sample panel or the surface of the sample, thereby preventing the generation of waste. Furthermore, other information regarding the spray (such as the appearance and quality of the film, color, flop, transfer efficiency, evaporation, film thickness, etc.) can be obtained from these images.

[0052] FIG. 1 shows various physical and logical components of one embodiment of a system for determining the spray characteristics of a powder or liquid spray 100. As shown, system 100 has several physical and logical components including a processing unit 102 (including one or more processors), a random access memory ("RAM") 104, a device interface 106, a user interface 108, a network interface 110, non-volatile storage 112, and a local bus 114 through which the processing unit 102 communicates with the other components. The processing unit 102 can execute or direct the execution of various modules as detailed below. The RAM 104 provides relatively responsive volatile storage to the processing unit 102. The user interface 108 enables an administrator or user to input, for example, via input devices such as a keyboard and mouse, and to provide information to an output device such as a display. The device interface 106 can be used to exchange data with other devices such as an imaging device 140 and / or an application device 142. The network interface 110 permits communication with other systems such as other computing devices and servers located remotely from the system 100, such as in a typical cloud-based access model. The non-volatile storage 112 stores an operating system and computer-executable instructions for implementing modules, as well as any data used by these services. Additional data described below can be stored in a database 116. During operation of the system 100, the operating system, modules, and related data can be retrieved from the non-volatile storage 112 and stored in the RAM 104 to facilitate execution.

[0053] System 100 includes one or more conceptual modules configured to be executed by processing unit 102. In one embodiment, these modules include a scan module 122, a mapping module 124, an adjustment module 126, and an output module 128. In some cases, some modules may be at least partially executed on dedicated hardware or separate hardware, while in other cases, at least some of the functions of some modules are executed on processing unit 102.

[0054] System 100 can be executed on computing device 26 and can access content on a server through a network such as the Internet via network interface 110. In further embodiments, System 100 may be executed only on a computing device or only on a server, or may be executed and / or distributed on any other computing device such as, for example, a desktop computer, a laptop computer, a smartphone, a tablet computer, a server, a smartwatch, a distributed computing device, or a cloud computing device(s). In some embodiments, the components of System 100 are stored and executed on a single computer system. In other embodiments, the components of System 100 are distributed among two or more computer systems that can be locally or remotely distributed.

[0055] When applying a solvent-based paint, if the film thickness is too thick, flow due to surface tension will occur, causing painting defects such as orange peel, so the film thickness is strictly controlled. To maintain an appropriate thickness, for example, it is necessary to balance several parameters as follows: · The local droplet flow of the atomizer, · The speed of the atomizer, · The distance between application paths (overlap), and · The number of overlaps.

[0056] The schematic diagram shown in FIG. 3 shows an example of a simplified coating trajectory in which the ESRB atomizer covers a flat surface with a series of coating trajectories.

[0057] The shape of the film on the surface is determined by the spray characteristics. The spray pattern or shape can be captured using the imaging device 140, for example, to continuously capture images from the central axis of the spray to its outer periphery. In this example, the relative abundance of droplets in the image is then utilized to determine the volume fraction as a function of the radial position. FIG. 4 shows an example of the volume fraction of the liquid as a function of the distance from the central axis of the spray acquired during the experiment.

[0058] In certain cases, assuming the spray is isotropic, the system 100 can interpolate the pattern and generate a film thickness shape considering the tip velocity of the atomizer and the flow rate of the liquid.

[0059] FIG. 5 shows an example of the theoretical film thickness and the experimental film thickness when the ESRB atomizer moves on a vertical plane at a speed (u) = 700 mm / s. As is clear from the experiment, the model is in good agreement with the experimental results. The system 100 can identify regions where the film thickness may vary significantly and recommend whether the overlap distance is too large. In some cases, a large overlap distance generally causes the film layer to undulate. In certain cases, the optimal overlap distance can be determined by drawing a regression line through the maximum value of the film thickness shape. Generally, when the standard deviation of the maximum value is large with respect to the regression line, the film is undulating and not uniform.

[0060] Generally, not all droplets have the momentum necessary to collide onto the surface. Droplets with a diameter below the penetration threshold may not be able to break through the boundary layer and do not contribute to film formation. The volume ratio of the total amount of droplets colliding with the surface, defined as the transfer efficiency. The transfer efficiency of the spray generally varies based on the values of specific operating parameters, while ensuring color matching at the same time. By improving the transfer efficiency, the amount of paint used is reduced, thereby reducing costs and also leading to a reduction in VOC emissions.

[0061] In some cases, theoretical film formation can be determined by assuming that droplets smaller than a predetermined cut-off diameter do not have the momentum to reach the surface. If the cut-off diameter is small (e.g., only droplets smaller than, for example, 5 μm do not collide), more droplets reach the surface, so the film becomes thicker. On the other hand, if the cut-off diameter is large (e.g., droplets smaller than, for example, 20 μm do not collide), the film becomes thinner and the smaller droplets become overspray. The transfer efficiency is defined as the volume ratio of droplets exceeding the cut-off diameter to the total number of droplets.

[0062] The appearance of the film (which may include color) applied by using the spray depends not only on the pigment of the paint but also on the spray characteristics and film formation. Unfortunately, many factors, such as the speed of the bell, the charge on the bell cup, temperature, and humidity, can affect the final color of the coating film. By determining the selected process parameters, system 100 can determine the control parameters of the spray system. In certain cases, system 100 can determine the spray characteristics of the droplet size and the spray pattern or shape.

[0063] The color of the coating film is generally directly related to spray characteristics, such as the size of the droplets. A particularly important indicator to monitor is flop, which is the change in brightness when the coating film is observed from different angles. As an example, the color on a painted panel can be measured and these measurements can be sent to the system. The received measurements can be combined with measurements of spray characteristics, as described herein, to generate a spray map. The spray map models flop as a function of spray characteristics. The formula for flop is based on the value of brightness measured at a specific angle with respect to specular reflection and can be represented, for example, by the following formula.

Number

[0064] The aluminum flakes contained in many metallic paints function like small mirrors and reflect light. The brightness caused by this reflection is maximum when observed at the reflection angle (based on the angle of incidence). However, the orientation of the flakes in the thick film is not always the same in some coating films.

[0065] As an example, the droplet size can be correlated with the color by using regression analysis. Figure 6 shows an example of how the spray map can ensure that the painting stays within the specifications. In this example, a single independent variable (the bell speed set to 46 RPM) is considered and the flop value is specified to be greater than 12. The average droplet size is D 32Although it is represented by, the painting map is not limited to using this statistical value. In the coating environment (such as a manufacturing line), instead of the operator spraying the part and checking whether the desired color can be obtained (the current common method), by using this system, the operator can measure the spray and analyze the measurement results. By using such measurement data, the spray map can, for example, determine recommendations for changes in operating parameters in order to keep within specifications. In the example of FIG. 6, in order to maintain the flop value within the allowable range (i.e., greater than 12), it is recommended to increase the bell speed by 5% and decrease D32 from 20.6 μm to 20.3 μm.

[0066] As another index to be monitored, there is a color vector (ΔE) based on the measured values of lightness, hue, and chroma received by the system. The formula for the color vector is as follows.

Equation

[0067] FIG. 7 shows the ΔE of a metallic paint and the Sauter mean diameter (D 32 ) measured in an experimental example for an atomizer operating at several bell speeds. In the shaded background, regions where the ΔE value exceeds 1.5 overlap, which is close to a level distinguishable by the human eye. There is a clear correlation between ΔE and the Sauter mean diameter. When the droplet size increases or decreases from 20.2 μm, a color change occurs. This color change becomes distinguishable by a human observer with only a change in the Sauter mean diameter of about 0.4 μm.

[0068] FIG. 2 shows a flowchart of a method for determining spray characteristics of a powder or liquid spray according to one embodiment. For clarity of explanation, method 200 is described with respect to determining the film thickness on a simple flat surface, but as will be understood by those skilled in the art, this method 200 is also applicable to more complex surfaces.

[0069] In block 202, the scan module 122 executes a scan via the imaging device 140 and determines measurement values of spray characteristics such as droplet size, droplet distribution, droplet velocity, and / or spray pattern or shape for a specific combination of paint and spray device with various operating parameters. In a further case, the scan module 122 can receive scan measurement values from the database 116, the network interface 110, or the user interface 108. The operating parameters can include, for example, bell speed, liquid or powder flow rate, shaping air flow rate, and charge amount. The scan measurement values refer to measurement values obtained at several positions and are measured, for example, at several radial positions at an arbitrary axial distance from an application device 142 (such as a bell cup of an ESRB atomizer, a spray nozzle, or a nozzle atomizer). In the example of the bell cup, while the imaging device 140 captures images at a constant frame rate, the bell cup can be moved radially at a constant speed to generate scan measurement values.

[0070] In block 204, the scan module 122 can process the acquired image / scan data and associate the diameter of each measured droplet with a spatial position. In some cases, this can be executed on the production line to confirm in real time that the spray meets the specifications.

[0071] Scan measurements can be performed to obtain the spatial position of each droplet in the spray. In a specific method, the atomizer is moved towards the device such that the first image is at the outer edge of the spray and the last image is at the center of the spray. In this case, the atomizer is arranged axially at a certain distance above (upstream) the device. Since the scan width, which is the distance from the initial position at the outer edge to the center, can be received and the time at which each image was taken is known, the position of each droplet can be determined as a function of the spray radius.

[0072] In block 206, mapping module 124 generates a spray map using the scan measurement values. The spray map includes a data set that includes a series of correlations between the measured droplet size and spray pattern or shape and spray application characteristics (e.g., color, flop, film formation, film appearance and quality, evaporation, powder form, and transfer efficiency). The spray map can be used to confirm that each paint spray applied falls within predetermined specifications. The spray map can be determined, for example, before paint is actually used on a production line. The spray map is generally unique for each paint and correlates the droplet size and spray pattern or shape with the final color information for different operating parameters of spray device 142. The operating parameters can include, for example, bell speed, liquid flow rate, shaping air flow rate, and charge amount.

[0073] The correlations of the spray map can be determined using, for example, calibration using a fractional factorial experiment method. During this calibration, one or a combination of the operating parameters is changed, and the effects (i.e., correlations) on the droplet size and spray pattern or shape can be determined using the received scan measurement values. Thus, by obtaining scan measurement values of the droplet size and / or spray pattern and shape, system 100 can determine the spray flux and then store the correlation mapping between the scan measurement values and the spray application characteristics (e.g., film thickness and coverage rate) on the surface. Further, by understanding the correlation between the scan measurement values and the operating parameters, system 100 can map how changes in the operating parameters affect the droplet size and spray pattern or shape, and thus can very accurately interpolate how such parameters ultimately affect the deposition on the spray surface.

[0074] Calibration of the spray map can be carried out using experiments (such as the Box-Behnken method), and it is possible to capture the fluctuations of important process parameters that occur when the operating parameters are changed. Color, film formation, film appearance and quality, evaporation, powder morphology, and / or transfer efficiency generally correlate with droplet size and spray pattern or shape, and thus generally tend to correlate with operating parameters. An example of a method for correlating all these parameters is to use multivariate analysis, where a new coating map can be created for each paint.

[0075] In certain cases, the data structure of each spray map is composed of coefficients that correlate the influence of operating parameters on spray characteristics (droplet size, droplet distribution, droplet velocity, and spray pattern or shape). One method of modeling the influence of operating parameters is to use the following regression model.

Equation

[0076] In some cases, spray application characteristics such as color, film formation, film appearance and quality, evaporation, powder morphology, and / or transfer efficiency can be identified and correlated with spray characteristics rather than corresponding operating parameters. This can be done to avoid the influence of process parameter variations such as differences in environmental factors (e.g., humidity and temperature) between the paint manufacturer's facility and the paint application environment (e.g., an automobile manufacturing line). In such cases, operating parameters (e.g., bell speed and fluid flow rate) are directly correlated with spray characteristics, and further those spray characteristics can be correlated with application characteristics (e.g., color, film formation, evaporation, and transfer efficiency). For example, the influence on the color of the paint can be correlated with changes in spray characteristics (e.g., droplet size, droplet distribution, droplet velocity, and spray pattern or shape). In the application environment, calibration procedures can be used to generate optimal spray characteristics and show the user how to adjust the spray to stay within specifications.

[0077] As an example, an operator can specify spray characteristics that result in optimal color and film formation while creating a painting map. Since the influence of each operating parameter in the trials specified by the design of the experiment is captured by the spray map, if external parameters affect the spray characteristics (such as temperature, an important concern between warm and cool months), the system can recommend corrective measures. For example, in a high-temperature environment, evaporation increases as a result and the droplets become smaller than the optimal size. Returning to the example of the bell speed in Figure 6, the system can use the spray map to recommend, for example, reducing the bell speed by a certain percentage to increase the droplet size.

[0078] Advantageously, the present embodiment provides a method in which color, film formation, and transfer efficiency are functions of spray characteristics (e.g., droplet size, droplet distribution, droplet velocity, and / or spray pattern or shape). When creating a spray map, the correlation of how the droplet size changes with the change of specific operating parameters can be determined, and then the correlation of how the change of these parameters affects color, film formation, and transfer efficiency can be determined.

[0079] The data of the spray map can be summarized in the database 116, and the system 100 can use such a spray map during production.

[0080] In some cases, in block 208, the adjustment module 126 can refer to the spray map and compare the application of the coating film with the predetermined specifications to determine various adjustments of the operating parameters. For example, if the droplet size is smaller than the value recommended in the specifications, the color of the paint may appear lighter than desired, and it can be recommended to increase the droplet size by lowering the bell speed. Advantageously, since the present system 100 can utilize the accurate correlations stored in the spray map, it can take into account changes in environmental conditions such as temperature and humidity (which may have a significant impact on spray characteristics) and quickly correct using the scan measurements performed at the original position of the spray.

[0081] Generally, the specifications regarding color and film formation are set by each paint manufacturer. During the creation of the spray map, the operator can input the specifications and tolerances. The spray map correlates the specifications and tolerances (e.g., color, film formation, and transfer efficiency) with the spray characteristics.

[0082] In some cases, the spray map can include multi-stage optimization based on user input. For example, when an operator specifies a certain tolerance range for film thickness and color, the spray map can be used to determine the optimal parameters for maximizing transfer efficiency while ensuring that the color and film thickness fall within the tolerance range.

[0083] In block 210, the output module 128 can output the spray map and / or recommendations to the user interface 108, the network interface 110, and / or the database 116. In some cases, the output module 128 can output the recommendations to the device interface 106 and instruct the coating apparatus to change one or more operating parameters as determined within block 208.

[0084] Advantageously, the inventors have confirmed that the droplet size and spray pattern or shape can be accurately correlated with spray deposition, rather than attempting to roughly estimate spray deposition from coating parameters (e.g., the rotational speed of the bell cup). This improvement in accuracy enables significant cost reduction and efficiency improvement in actual operation.

[0085] In an example of this embodiment applied to pharmaceutical use, the spray characteristics can be controlled by adjusting specific operating parameters such as, for example, liquid supply rate, concentration, or viscosity. By monitoring the effects of different combinations of these process parameters on the spray characteristics, a response map can be generated using, for example, regression analysis. The spray map can be used to recommend to the operator or automatic controller a method of adjusting the parameters so that the particle size, which is an important process parameter, is maintained within the specification range, taking into account each operating parameter.

[0086] As an example of mapping operating parameters, correlating the distance from the spray nozzle to the pattern or shape of the spray (i.e., the relative volume of the spray) can be mentioned, thereby determining the evaporation rate. The evaporation rate is the attenuation of the rate at which the volume decreases due to the formation of a shell by a solid that hinders the diffusion of the solvent to the outer surface of the droplet. After creating a spray map using the system 100, for example, by using regression analysis, the optimal distance from the nozzle at which the size of the droplets indicating the completion of particle formation does not change can be recommended.

[0087] In a particularly advantageous case, as shown in FIG. 8, the imaging device 140 can include a device for characterizing fast-moving particles so that it can characterize in real time the size of the droplets of the spray and the pattern or shape of the spray. The device 140 can include an illumination module 402, a camera module 404, and an image analysis module 406. These modules can be interconnected or communicate with each other using any suitable method. In some cases, the device 140 can further include a housing 408 that houses the camera module 404 and the illumination module 402, and in some cases, the image analysis module 406 as well. In other cases, the image analysis module 406 may be located at a location remote from the housing 408.

[0088] In the following disclosure, the functions and operations of the illumination module 402, the camera module 404, and the image analysis module 406 will be described as being executed on the device 140, but it should be understood that it is also possible for the system 100 to execute one or more of these operations and functions.

[0089] FIG. 9 shows an exemplary embodiment of the illumination module 402, including a light source 410 (e.g., a stacked laser diode array, a light emitting diode (LED), or a near infrared (NIR) laser diode, etc.), a pulse generator 412 (also called a current amplifier or a function generator), a synchronization substrate 418, and an optical element 420 for adjusting the beam. In one embodiment, a laser diode array can be used as the light source 410 because it is high-brightness and compact. In some cases, the light source 410 includes a suitable driver such as a laser driver for the laser diode array. In most cases, a short flash in the order of nanoseconds is required to freeze the movement of the particles, so the light intensity must be made high enough to properly irradiate the particles. Using the nominal value of the light intensity of a typical laser diode, since its duration is short, there may be a case where sufficient light energy is not supplied to capture an image with a camera sensor. Therefore, in such a short flash, the optical power must be increased significantly. To achieve this, the illumination module 402 includes a pulse generator 412 that can supply a current to achieve a high-intensity nanosecond flash. As an example, the energy of the laser pulse is about 65 uJ, and the duration of the flash can be about 10 ns to 100 ns.

[0090] Advantageously, the illumination module 402 can use a high-output NIR laser diode or LED instead of a low-output visible wavelength laser. Advantageously, the NIR laser can be made more compact than a visible spectrum laser with the same output. There is an inverse relationship between the output and the wavelength of the laser. While most other methods use visible wavelengths, the illumination module 402 can use an NIR laser diode to obtain equivalent brightness on the captured image and can use light that more effectively penetrates the spray.

[0091] The light generated from the light source 410 may be a combination of beams from each diode or LED. For image processing, the optical element 420 can be used to adjust the beam into a uniform flat-top shaped non-coherent light or semi-coherent light. In most cases, the beam should be flat-top in order not to amplify a specific part of the image, and thus the image analysis will be accurate. A uniform flat-top shape generally means that various regions of the entire laser have the same brightness. Most lasers, in their natural state, have a brighter center of the beam, and the brightness decreases as the distance from the center increases. In image processing, this characteristic is disadvantageous because uniform illumination is desired for all parts of the image. If a specific part is over-illuminated, it may result in overexposure and the loss of parts of the captured image and data, or if the amplified part is at the appropriate exposure level, other parts may be underexposed and data may be lost. Optical components may be used to create a laser beam that has the same or similar brightness at all positions across the laser beam, i.e., a laser beam whose shape is said to be "flat".

[0092] Generally, in the case of coherent light, a prominent diffraction pattern is formed around the object in the image plane, making image analysis more difficult. Therefore, the beam is generally composed of non-coherent light or semi-coherent light. In an example of the optical element 420, the beam can be formed by first passing it through a homogenizing light rod that serves to homogenize the light and reduce coherence. Next, the coherence of the light can be further reduced by passing the beam through a diffuser plate. The beam can then pass through a device that collimates the light, such as an aspheric doublet lens for example. Additionally, a microlens array, a liquid light guide, or an optical fiber cable can also be used. It should be understood that any suitable method can be employed to reduce the coherence of the light.

[0093] The light source 410 can be driven by a pulse generator 412 that receives a trigger signal from the synchronization board 418. This pulse generator 412 can generate, for example, high-voltage and / or high-current pulses with a specific short duration of, say, 1 nanosecond. The duration of the optical pulse and the voltage and current parameters can be controlled using the pulse generator 412 that receives the trigger signal from the synchronization board 418. This trigger signal is generally generated by the camera module 404 and sent to the synchronization board 418 to correct any noise between the output of the camera module 404 and the illumination module 402. The trigger signal can be an electrical pulse output by a camera used as a trigger to activate the light source 410 to illuminate the field of view. In most cases, the trigger signal is automatically generated just before the camera is set to take an image.

[0094] The camera of the camera module 404 outputs a synchronization signal that may contain noise. In some cases, due to such noise, if the synchronization signal is sent directly to the pulse generator 412, it may cause the light source 410 to malfunction. Thus, the synchronization board 418 can be used between the camera module 404 and the pulse generator 412. The synchronization board 412 can, in some cases, accurately detect the camera's signal above the background noise and output a noise-reduced signal to the pulse generator 412. The synchronization board 418 can use any suitable noise reduction algorithm.

[0095] Upon receiving the trigger signal from the synchronization board 418, the pulse generator 412 then sends a pulse (often a high-voltage, high-current pulse) to the light source 410, and the pulse is converted into light. The connection from the pulse generator 412 to the light source 410 generally has a very low inductance. In many cases, the pulse generator 412 can be placed close to the light source 410 to maximize the energy transfer to the light source 410.

[0096] Generally, in other methods, the magnification of the objective lens changes with the distance to the object to be photographed. For this reason, it is difficult for the user to calibrate the particles and droplets randomly distributed in the space. In order to eliminate the need for such focusing and calibration, the camera module 404 can use a telecentric lens. Since the telecentric lens only accepts light perpendicular to the lens surface, any object at a distance within the field of view remains the same size. The inventors conducted tests of examples to determine an appropriate combination of (i) the resolution and pixel size of the camera, and (ii) a telecentric lens with an appropriate magnification, focal length, and depth of field suitable for capturing small particles such as 5 μm. As a result, it was possible to measure particles up to 5 microns used in hazardous location requirements. In the test, the resolution was in the range of 6 to 18 MPix, the pixel size was 0.9 μm to 3 μm, the magnification was 0.5 times to 3 times, and the focal plane distance (working distance) was 100 mm to 400 mm.

[0097] In some cases, the optical output can be limited to meet the hazardous location (Haz Loc) requirements. In such cases, by keeping the optical output below 85 μJ per pulse, the intrinsic safety of the light source 410 can be ensured. As an advantage, the combination of the camera and lens of the camera module 404 can handle high sensitivity even at low illuminance / low output, similar to a camera with physically small pixels to use a telecentric lens with high transmittance and low magnification and to supplement the low-magnification lens. With this arrangement of the camera module 404, the illumination module 402 can use a small and low-output laser. Advantageously, it is possible to use lenses with various magnifications at the same working distance without changing the required working position. Generally, lenses with low magnification are physically small, and such lenses are more compact than other methods.

[0098] Housing 408 can advantageously accommodate all optical and electronic components internally. This fixes the positions of the lighting module 402 and the camera module 404, eliminating the need for the user to worry about finding generally appropriate settings and simplifying the measurement procedure. Housing 408 also advantageously protects the components from spray mist environments and other external environments. This feature is very important because housing 408 is generally placed in-line and can in some cases be placed inside sprays or particle streams. In such environments, housing 408 can effectively protect the components from moisture. Housing 408 also advantageously isolates its internal components from the external environment. In some cases, it can function even in spray environments with a very high risk of explosion due to the chemical composition of the particles, such as in dangerous locations or industrial sites. In the event of a spark or small explosion inside the housing, it is extremely important to prevent it from causing further ignition or explosion inside the spray environment.

[0099] Advantageously, the lighting module 402 can miniaturize the housing 408 and minimize the overall size of the device 140. FIG. 10 shows an exemplary embodiment of the housing 408. In this example, the lighting probe 454 of the housing 408 with the lighting module 402 can be cylindrical. In this example, the camera probe 452 of the housing 408 with the camera module 404 can also be cylindrical. The image processing unit 456 of the housing 408 with at least the image analysis module 406 can be connected to the camera probe 452 and the lighting probe 454. The housing 408 can include conduits for accommodating communication channels for communication between components. In other examples, it will be understood that any suitable configuration can be used for the arrangement of the housing and the probes. In this example, the housing 408 is made of stainless steel, but in further examples, it can be other suitable materials such as aluminum.

[0100] FIG. 16 shows a cross-sectional view of an example of the camera probe 452, and FIG. 17 shows a cross-sectional view of an example of the laser probe 454. In some cases, each of the illumination probe 454 and the camera probe 452 can be provided with a front window that forms a housing sealed to prevent the intrusion of dust and liquid. In some cases, a purge plate can be disposed in front of the front window of the camera probe 452 to prevent the accumulation of particles and debris.

[0101] In this example, the camera probe 452 includes a front cover 602, a purge inlet 604, a lens assembly 606, and a camera 608. In this example, the laser probe 454 includes a front cover 702, a purge inlet 704, a collimating optical element 706, a homogenizing optical element 708, a laser 710, a synchronization substrate 712, and a pulse generator 714.

[0102] The probe can be manufactured from any suitable material, such as aluminum and a quartz disk for the window. The glass for the window can be compressed between an internal retaining ring and the probe body. Two O-rings can be used to seal each window. One is placed in a groove and compressed on the probe body, and the other is placed in a groove within the window and compressed around the quartz glass. A threaded hole can be provided within the body of the window, and a through hole can be provided within the probe body. For example, one such hole can supply compressed air to the window portion, creating an air curtain of air flow to keep droplets away from the glass surface and keep the display screen clean.

[0103] FIG. 12 shows a schematic diagram of an exemplary embodiment of the image analysis module 406. In this example, the image analysis module 406 includes a plurality of physical and logical components, including a processing unit ("PU") 460, a random access memory ("RAM") 464, an input / output (I / O) interface 472, a data storage area 480, and a local bus 484 that enables the PU 460 to communicate with other components. The PU 460 can include one or more processors, such as a central processing unit or an image processing unit. The RAM 464 provides a relatively responsive volatile storage area for the PU 460. The I / O interface 472 enables a user to input, for example, via a keyboard and a mouse. The I / O interface 472 can also output information to output devices such as, for example, a display and a speaker. The I / O interface 472 can also enable communication with other modules and / or systems, or computing devices. The data storage area 480 stores an operating system, a program including computer-executable instructions for image analysis, and derived or related processes. During operation, the operating system, the program, and the data are retrieved from the data storage area 480 and stored in the RAM 464 to facilitate execution. In one embodiment, the PU 460 can be configured to execute various conceptual sub-modules, such as, for example, a trigger sub-module 490 and an analysis sub-module 492. In a further embodiment, the functions of the image analysis module 406 can be executed on appropriate dedicated hardware or on a specific microprocessor. In some cases, the I / O interface 472 can include, for example, a user interface through a web browser or a cloud computing interface, thereby facilitating integration with existing systems.

[0104] The image analysis module 106 can execute a number of processes, such as the following, for example, with respect to paint spraying. ·Perform statistical and visual results for comparing various nozzles as follows: ·Move the nozzle into the field of view of the camera, ·Obtain an image of the droplets from the spray, ·Determine in real time statistics regarding the size distribution of the droplets, ·Collect as much data as possible required from different nozzles and sprays, and ·Save the data for comparison in post-processing. ·Verify that there is no damage to the nozzle. ·Verify the spray during the cleaning cycle and / or when changing the paint color to ensure that the spray characteristics remain unchanged compared to the paint / nozzle manufacturer's recommended values or the facility's specifications. ·Prevent improper painting by ensuring the uniformity of the spray before applying the paint. ·As described above, measure the characteristics and statistics of the droplet size and confirm that the statistical values do not change within a specific tolerance range, thereby ensuring that the spray characteristics remain unchanged over time compared to the paint or nozzle manufacturer's recommended values or the facility's specifications.

[0105] Next, referring to FIG. 13, shown therein is a method 500 for evaluating the characteristics of fast-moving particles according to an embodiment. This method 500 can be executed when at least some of the sprays are located between the illumination probe 454 and the camera probe 452.

[0106] In block 502, the trigger sub-module 490 or the camera module 404 transmits a trigger to the illumination module 402 using, for example, a TTL (Time-to-Live) trigger output signal.

[0107] In block 504, the illumination module 402 generates a pulse output such as a laser pulse.

[0108] In block 506, the camera module 404 captures an image on the image sensor. In some cases, such an image may be a shadowgraph image of particles located between the illumination module 402 and the camera module 404.

[0109] In block 508, the analysis sub-module 492 receives the image captured from the camera module 404.

[0110] In block 510, the analysis sub-module 492 determines the characteristics of the particles, such as size and shape, detected in the captured image, and in some cases, determines statistical values based on such characteristics. Various suitable statistical quantities are determined from particle characteristics such as, for example, the mean value, standard deviation, Sauter mean diameter, minimum size, maximum size, percentile, volume percentile, and span.

[0111] In block 512, the analysis sub-module 492 outputs the analysis results. For example, the shadowgraph image, size distribution, and characteristic evaluation of the statistical quantity are output to the data storage area 480 or to a display or other computing device via the I / O interface 472.

[0112] In an exemplary embodiment, the camera module 504 includes an image sensor, an optically isolated trigger, a flash as a light source, and two GPIOs (General-Purpose Input / Output). The output of the flash can be DC-isolated using an optical coupler as shown in the circuit diagram of FIG. 14, protecting the camera module 104 and the image analysis module 406 from surges. The output of the optical coupler can be used as an open collector or open emitter output. That is, the output signal can be connected to ground or the power supply voltage. The exposure of the camera can be synchronized with the light source 410 so that an image is recorded by the image sensor. The formed image can be, for example, a shadowgraph of the particles within the field of view of the image sensor. The shadowgraph generates a shadow used to identify the form of the particles. The form can be any geometric information about the particles and includes, for example, diameter, perimeter, area, aspect ratio, and eccentricity.

[0113] Shadowgraphy is a technique that generates and analyzes the shadow of an object rather than the object itself. In shadowgraphy, since the light source 410 is placed behind the imaging object, the object blocks the light from reaching the camera, and a shadow (dark region) is formed on the camera sensor. Since these shadows have exactly the same shape as the object itself, the form of the object can be determined by detecting and analyzing the shadows in the image.

[0114] In most cases, the image analysis module 406 can consider various factors such as, for example, (i) whether the droplets or particles are in focus or out of focus and how to identify and correct such effects, (ii) what impact the movement of the droplets or particles has on the image quality and measurement, and (iii) how accurately the edges of the particles are defined. Further, the image analysis module 406 can automatically perform image acquisition, image processing, user interface, and data processing. The image captured by the camera module 404 can be either processed in real time by the image analysis module 406 or stored in the data storage area 480 and processed later.

[0115] The parameters regarding the flash output of the camera module 104 can be set by the user. In some cases, the flash output can have two modes: high active and low active. In the high active mode, the digital output is set to "high" during exposure. In the low active mode, the digital output is set to "low" during exposure. The flash delay sets the delay time of the digital output. After the exposure starts, the activation of the digital output is delayed by the time set by the flash delay. The digital output that sets the switching time of the digital output by the duration operates for the time set in the duration.

[0116] To capture a high-contrast image of the particle spray, in one example, the flash (e.g., an array of light-emitting diodes (LEDs)) can be triggered for hundreds of nanoseconds. Since the exposure time is short, generally a very high illuminance is required. As an example, the flash can include a high-output green LED (PT-120LED, consuming 30 A at 5.9 V and outputting a maximum luminous flux of 5200). As an example, an LED driver module that can apply high-current (up to 240 A) and high-voltage (up to 100 V) pulses to the LED can be used. This LED driver can generate pulses with a pulse width of 60 ns to 1 μs. The pulse width can be determined by the trigger input signal.

[0117] Generally, since the maximum pulse width that the camera module 404 can generate is only 40 μs, in some cases, the input signal of the LED driver cannot be triggered by the flash output signal of the camera module 404. To achieve a short control pulse, it is possible to use a programmable version of the pulse generator 412.

[0118] As an example, the pulse generator 412 has four types of trigger modes as shown in FIG. 15, but any suitable number and type of triggers can be used. By selecting an appropriate trigger mode, an appropriate arrangement of the flashes can be determined. Trigger modes 1 and 4 (Trgmode1 and Trgmode4) can be used when the flash output signal of the camera module 104 is set to active high. Trigger modes 0 and 5 (Trgmode0 and Trgmode5) can be used when the flash output signal of the camera module 404 is set to active low. The number of pulses generated can be determined by the user via the shots syntax.

[0119] While the pulse generator 412 is connected to the LED driver, the voltage mode is active by default and can be used for calibration to change to the current mode. min is the minimum value of the voltage (a value slightly higher than the threshold voltage of the diode, for example, 12V), and the overcurrent is the maximum diode current used for calibration. If an error occurs during calibration, min is shown to need to be increased. When the LED is replaced, the pulse generator cannot detect the change, so calibration needs to be performed again. When calibration is completed, the mode can be automatically switched to the current mode. The laser diode 110 can be turned on in the current mode using an appropriate syntax after the current, voltage, repetition frequency, trigger mode, and number of shots are adjusted.

[0120] Advantageously, the device 140 can measure the size of particles up to, for example, 5 microns. In one example, pulses with a duration of 10 to 100 nanoseconds can be generated. In one example, the wavelength of the light was 532 nm or 905 nm, but it can be changed according to each specific application. Depending on the optical system, in one example, the depth of field can range from 50 μm to 1 mm.

[0121] Advantageously, the device 140 can provide a modular design that can be used in a plurality of environments and industries. The system 100 enables easy replacement of certain components for different applications without changing the functionality and operating principles of the device 140. For example, the camera can be changed to high resolution or low resolution, the pixel size can be increased or decreased, or the lens can be changed to a higher magnification or lower magnification.

[0122] Although the present invention has been described with reference to certain specific embodiments, various changes will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined within the claims appended hereto. The entire disclosure of all the cited references above is incorporated herein by reference.

Claims

1. A method executable by a processor for determining spray characteristics of a powder or liquid spray, the method comprising: receiving the spray characteristics of the powder or liquid spray; generating a spray map including correlating the received spray characteristics with spray application characteristics, operating parameters of a spray device, or both, wherein the correlation is determined using calibration of scan measurements; outputting the spray map.

2. The method of claim 1, further comprising adjusting operating parameters of the spray device to achieve a specific performance in the application of the spray using the spray map.

3. The method of claim 1, wherein the spray characteristics include one or more of droplet size, droplet distribution, droplet velocity, and spray pattern or shape.

4. The method of claim 1, wherein the operating parameters include one or more of bell speed, flow rate, shaping air flow rate, and electrostatic charge.

5. The method of claim 1, wherein the scan measurements are performed at several different positions.

6. The method of claim 5, wherein the spray device moves radially and generating the spray map includes determining the spatial position of each droplet as a function of the spray radius using the time at which each received scan was performed.

7. The method of claim 1, wherein the calibration includes changing one or more operating parameters and determining the effect on the spray characteristics using the scan measurement values.

8. The method of claim 1, wherein the spray map is generated using a model that correlates the spray characteristics to the operating parameters.

9. The method of claim 1, wherein generating the spray map includes correlating changes in spray characteristics with changes in operating parameters and correlating changes in spray characteristics with spray application characteristics.

10. The method of claim 1, wherein the spray application characteristics include one or more of color, film formation, film appearance and quality, evaporation, powder form, and transfer efficiency.

11. A system for determining spray characteristics of a powder or liquid spray, the system comprising one or more processors in communication with a data memory, a scan module that receives the spray characteristics of the powder or liquid spray Generating a spray map that includes correlating the received spray characteristics with spray application characteristics, operating parameters of the spray device, or both, wherein the correlation is determined using calibration of the scan measurement, and outputting the spray map, and a mapping module for performing the above.

12. The system according to claim 11, further comprising an adjustment module that adjusts the operating parameters of the spray device to achieve specific performance in the application of the spray using the spray map.

13. The system according to claim 11, wherein the spray characteristics include one or more of droplet size, droplet distribution, droplet velocity, and spray pattern or shape.

14. The system according to claim 11, wherein the operating parameters include one or more of bell velocity, flow rate, air flow rate for shaping, and electrostatic charge.

15. The system according to claim 11, wherein the scan measurement is performed at several distinct positions.

16. The system according to claim 15, wherein the spray device moves radially, and the generation of the spray map includes determining the spatial position of each droplet as a function of the spray radius using the time at which each scan was taken.

17. The system according to claim 11, wherein the calibration includes changing one or more operating parameters and determining the effect on the spray characteristics using the scan measurement values.

18. The system according to claim 11, wherein the spray map is generated using a model that correlates the spray characteristics with the operating parameters.

19. The system according to claim 11, wherein the generation of the spray map includes correlating spray characteristics with changes in operating parameters and correlating changes in spray characteristics with spray application characteristics.

20. The system according to claim 11, wherein the spray application characteristics include one or more of color, film formation, film appearance and quality, evaporation, powder form, and transfer efficiency.

Images