JP2013144274A - Method for measuring amount of droplet, method for measuring particle size distribution, and droplet discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring an amount of droplets capable of accurately measuring the amount of droplets, and a droplet discharge device capable of accurately controlling the amount of droplets by using this.SOLUTION: The first analysis controller 9 determines the quality of a nozzle 13 by crawling up of a liquid and calculates the volume of a spherical body 31 based on an image data of a leading end part of the nozzle 13 photographed by a first camera 7 and a spherical body 31 formed in the leading end part, and performs the feedback control of the amount of droplets discharged from a droplet discharge head based on the calculated volume.

Description

  The present invention relates to a droplet amount measuring method for measuring the amount of droplets ejected from a nozzle, a particle size distribution measuring method for measuring the particle size distribution of particles contained in the ejected liquid, and a droplet ejecting droplets from the nozzle. The present invention relates to a discharge device.

  In the droplet discharge device, a droplet discharge head including a pressure supply device and a nozzle is provided, and when the pressure supply device pushes the internal liquid to the nozzle, the liquid is discharged from the nozzle as droplets. To do. Even if the same amount (volume) of liquid (liquid material) is extruded from the pressure supply device, the amount of liquid droplets ejected from the nozzle (sometimes referred to as the ejection amount) is due to manufacturing variations of the liquid droplet ejection head and nozzles. It depends on the shape and type of liquid. Since the droplet amount is an important factor that determines the quality of the pattern formed by the applied liquid, control of the droplet amount is important.

  Therefore, conventionally, a droplet is discharged from a nozzle and the amount thereof is measured, the measured droplet amount is compared with a target droplet amount, a difference is obtained, and the liquid to be pushed out from the pressure supply device to the nozzle is measured. Feedback control for adjusting the amount is performed (for example, Patent Document 1).

  Moreover, measuring the application | coating shape of the pattern formed on the workpiece | work is also performed (for example, patent document 2).

  On the other hand, the droplet discharge device is also used for manufacturing a light emitting element such as an LED (Light Emitting Diode) package. In manufacturing a light emitting element, a liquid in which phosphor particles are mixed with resin is discharged from a droplet discharge device. In the light emitting element, not only the volume of the ejected liquid but also the dispersion state (density) and particle size of the phosphor particles contained in the liquid affect the chromaticity of the light emitting element. For this reason, a manufacturing method has been proposed in which a light emitting element is turned on to discharge a droplet while measuring the chromaticity, and the discharge is stopped when the target chromaticity is reached (for example, Patent Document 3).

JP 2002-542920 A JP 2003-28616 A JP 2009-260244 A

  However, the conventional techniques 1 and 2 as described above have a problem in that the droplet amount feedback control cannot be performed with high accuracy and the droplet amount cannot be controlled with high accuracy.

  For example, in Patent Document 1, a droplet amount is measured using a weight sensor. In the measurement using the weight sensor, if the distribution of particles contained in the liquid to be discharged varies, the volume is converted even with the same weight. In other words, if the particles are not uniformly dispersed in the liquid mixture obtained by mixing particles with different specific gravities in the liquid, even if the weight is the same in the part with a high particle content and the part with a low particle content The volume changes. In such a case, even if feedback control is performed, the amount of droplets varies.

  In addition, Patent Document 1 describes that a visual device for measuring the diameter, area, and volume of a droplet may be used as a measuring device other than the weight sensor, but specifically describes anything. It has not been. Since the liquid droplets flying in the air are deformed by air resistance, it is considered that the area and volume cannot be accurately detected even if the diameter is measured.

  In Patent Document 2, the shape of a pattern formed on a work changes under the influence of wettability between the work and liquid. For this reason, it is considered that the volume of the droplet cannot be measured with higher accuracy than the pattern applied on the workpiece.

  On the other hand, in the manufacturing method described in Patent Document 3, there is a problem that the manufacturing cost of the light emitting element increases and the product cannot be provided at low cost.

  In other words, the procedure of discharging the droplet while turning on the light emitting element and measuring the chromaticity and stopping the discharge when the target chromaticity is reached is complicated and takes a long time to manufacture. . In order to reduce the manufacturing cost, it is necessary to develop a droplet discharge device that can check the dispersion state (density), particle size, etc. of the phosphor particles in the liquid to be discharged and manage it including the chromaticity of the liquid. Become.

  As a factor for changing the chromaticity of the liquid, in addition to the dispersion state (density) of the phosphor particles, the particle size distribution of the phosphor particles can be increased. A laser light scattering method (laser diffraction method) is generally used to measure the particle size distribution per unit area. In the laser light scattering method, the particle size is identified from the scattering pattern, and the number of particles is identified from the intensity of the scattered light.

  However, when measuring the particle size distribution of the liquid, if the sample has a thickness such as a liquid having a high viscosity, or if the particle concentration is high, multiple scattering of light scattered by the particles tends to occur. When multiple scattering occurs, the scattering angle is widened and light scattered from small particles is considered, and an error occurs in the particle size distribution. The liquid containing the phosphor particles used in the manufacture of a light emitting device in which phosphor particles are mixed with resin is exactly in this state.

  In order to eliminate such an error, it is also conceivable to measure the particle size distribution using a laser light scattering method using a diluted liquid as a sample. However, this method requires a dilution step, and it cannot be said that the particle size distribution per unit area obtained with the diluted liquid is the same as that of the liquid (stock solution) before dilution, which is not accurate.

  The present invention has been made in view of the above problems, and a first object is to provide a droplet amount measuring method capable of measuring the droplet amount with high accuracy, and to control the droplet amount with high accuracy by using this method. It is to provide a droplet discharge device.

  The second object of the present invention is to provide a laser light scattering method for particle size distribution in a liquid without diluting the liquid, for example, even in a liquid in which phosphor particles are mixed in a resin. A droplet discharge apparatus that can be used and measured, and that can be used, for example, in a manufacturing process of a light-emitting element, can be used to manage the liquid droplet discharge apparatus including the chromaticity of the liquid to be discharged. Is to provide.

  In order to solve the above problems, a droplet amount measuring method of the present invention is a droplet amount measuring method for measuring a droplet amount ejected from a nozzle, and is just before separation formed on the tip of the nozzle. A pass / fail judgment step for detecting the quality of the liquid droplet just before separation, detecting the amount of the droplet rising to the outer periphery of the nozzle based on the taken image data, And a volume calculation step of calculating a volume of the droplet determined to be good in the determination step based on the image data used for detecting the amount of scooping.

  According to this, since the droplet amount is measured not as a weight but as a volume, even if the distribution of particles contained in the discharged liquid varies, the discharged droplet amount can be made constant. In addition, in obtaining the droplet amount as a volume, an image of the droplet formed immediately before separation formed on the tip of the nozzle is taken, and the volume is calculated from this. Therefore, it is possible to calculate more accurately than taking an image of a droplet flying in the air in which deformation due to air resistance has occurred or an image of a droplet that has already landed, and calculating the volume.

  In addition, from the image of the droplet immediately before separation, which was formed at the tip of the nozzle, the amount of droplet rising to the outer periphery of the nozzle was detected, and the quality of the droplet was judged to be good. Since only droplets are targeted, it is possible to measure the amount of droplets more accurately.

  In order to solve the above problems, a droplet discharge device of the present invention is a droplet discharge device that discharges droplets from a nozzle by extruding a liquid from a pressure supply unit connected to the nozzle. An imaging unit that images the formed droplet and nozzle immediately before separation, and an amount of rising of the droplet to the outer peripheral portion of the nozzle based on image data captured by the imaging unit, and immediately before separation A pass / fail judgment unit for judging pass / fail of the liquid droplet, a volume calculation unit for calculating the volume of the liquid droplet judged as good by the pass / fail judgment unit based on the image data used for the detection of the scooping amount, And a feedback control unit that adjusts a liquid push-out amount in the pressure supply unit based on the volume of the droplet calculated by the volume calculation unit.

  According to the above configuration, the liquid ejection amount in the pressure supply device is adjusted on the basis of the droplet amount measuring method of the present invention, so that it is possible to provide a droplet discharge device capable of controlling the droplet amount with high accuracy.

  The droplet discharge device of the present invention may further include a nozzle cleaning unit that cleans the nozzles when the pass / fail determination unit determines NO.

  In order to solve the above problems, the particle size distribution measuring method of the present invention is a particle size distribution measuring method for measuring the particle size distribution of particles contained in a liquid using a laser light scattering method. A thinning step for sandwiching and thinning the particles having the largest diameter among the particles contained in the liquid into a thin layer, and a scattered light obtained by irradiating the thinned liquid with laser light and scanning And a particle size distribution measuring step for measuring the particle size distribution based on the above.

  According to this, the liquid is sandwiched between transparent plates and thinned so that the particles do not overlap, so even if the particle concentration is high or the particles are mixed in the resin, the particle size of the particles in the liquid Distribution can be measured using laser light scattering without diluting the liquid.

  In order to solve the above problems, a droplet discharge device of the present invention is sandwiched between transparent plates in a droplet discharge device that discharges droplets from a nozzle by extruding liquid from a pressure supply unit connected to the nozzle. Particle size measurement that measures the particle size distribution based on the scattered light obtained by irradiating and scanning a laser beam that is thinned to the thickness of the particle having the maximum diameter among the particles contained in the liquid And a chromaticity predicting unit that predicts the chromaticity of the liquid by calculating the density and area ratio of the phosphor particles in the liquid based on the particle size distribution measured by the particle size distribution measuring unit. It is a feature.

  For example, in a droplet discharge device used in a manufacturing process of a light emitting element such as an LED package, a droplet discharge device that can manage the chromaticity of the liquid to be discharged is desired. According to the above configuration, the particle size distribution measuring unit measures the particle size distribution of the particles in the liquid, and the chromaticity prediction unit calculates the density and area ratio of the phosphor particles in the liquid based on the particle size distribution. Predict chromaticity. Accordingly, for example, it is possible to provide a droplet discharge device that can be used for manufacturing a light emitting element such as an LED package and that can manage the chromaticity of the liquid to be discharged.

  Accordingly, there is an effect that it is possible to provide a droplet amount measuring method capable of measuring the droplet amount with high accuracy, and to provide a droplet discharge device that can control the droplet amount with high accuracy by using this method.

  This also provides, for example, a particle size distribution measuring method for measuring the particle size distribution of the particles in the liquid without diluting the liquid even when the phosphor particles are mixed in the resin. By providing it for the manufacture of light emitting elements such as LED packages, it is possible to provide a droplet discharge device that can be managed including the chromaticity of the liquid to be discharged.

It is explanatory drawing which shows the structure of the droplet discharge apparatus concerning this Embodiment. (A) (b) is explanatory drawing which shows the structural example of the pressurization supply device with which the droplet discharge head of the said droplet discharge device is equipped, (a) is a piston pump type pressurization supply device, (B) is an auger pump type pressure feeder. It is explanatory drawing which shows the positional relationship of the 1st camera with which the said droplet discharge apparatus is equipped, a table, and the nozzle of a droplet discharge head. It is explanatory drawing of the preparation part with which the said droplet discharge apparatus is equipped. It is explanatory drawing which shows the particle size distribution measuring method used for the said droplet discharge apparatus, and the method of calculating | requiring the chromaticity of a liquid by calculating | requiring the density and area ratio of a fluorescent substance particle from the obtained particle size distribution. It is explanatory drawing which shows the method of exciting the fluorescent substance particle and measuring the chromaticity of a liquid used for the said droplet discharge apparatus. The nozzle of the droplet discharge head with which the above-mentioned droplet discharge device is equipped is shown, (a) is a sectional view of an example of a nozzle, and (b) is a sectional view of an example of a water repellent layer with which a nozzle is provided. It is a functional block diagram of each 1st and 2nd analysis control part of the said droplet discharge device. (A) and (b) both show the state of the nozzle of the droplet discharge head provided in the droplet discharge device, and (a) is a normal image taken in a state where the liquid is not pushed out from the pressure supply device. FIG. 5B is a photograph of the nozzle in a state and a sectional view of the nozzle, and FIG. 5B is a photograph of the nozzle in an abnormal state and a sectional view of the nozzle taken in a state where the liquid is not pushed out from the pressurizer. (A)-(c) shows the state of the spherical body formed in the front-end | tip part of the nozzle of the droplet discharge head with which the said droplet discharge apparatus is equipped, (a) (b) Sectional drawing of the normal nozzle currently formed normally is shown, (c) shows sectional drawing of the abnormal nozzle in which the spherical body is not normally formed. It is explanatory drawing which shows the specific example which determines the abnormality of the spherical body formed in the front-end | tip part of the nozzle of the droplet discharge head with which the said droplet discharge apparatus is equipped. (A) and (b) are both photographs showing images obtained by thinning the droplets ejected from the droplet ejection head provided in the droplet ejection apparatus, and (a) is a normal light. The photographed image (b) is a photograph taken by illuminating light having a single wavelength excited by the phosphor particles in the droplet. It is a flowchart which shows the flow of the calibration in the said droplet discharge apparatus. It is a flowchart which shows the flow of the droplet volume measurement process in the said droplet discharge apparatus. It is a flowchart which shows the flow of the liquid dispersibility determination process in the said droplet discharge apparatus.

  Hereinafter, embodiments of the present invention will be described in detail. In the present embodiment, a droplet discharge device used in the step of applying a liquid obtained by mixing phosphor particles in a resin in the manufacture of an LED that is a light emitting element will be exemplified.

(Configuration of droplet discharge device)
FIG. 1 is an explanatory diagram showing a configuration of a droplet discharge device according to the present embodiment. As shown in FIG. 1, the droplet discharge device 1 includes a droplet discharge head 3, a head drive unit 4, a table 5, a table drive unit 6, a discharge property monitoring unit 19, and a dispersibility monitoring unit 10. Although not shown in FIG. 1, the droplet discharge device 1 includes a nozzle cleaning device 71 (see FIG. 8), a liquid stirring mechanism 72 (see FIG. 8), and the like.

  The droplet discharge head 3 includes a pressure supply device 15 and a nozzle 13 attached to the pressure supply device 15. The pressure supplier 15 is a pump that pushes the liquid to the nozzle 13 by applying a pressure set according to the amount of liquid to be discharged to the liquid. The nozzle 13 discharges the liquid supplied from the pressurized supply device 15 through the opening at the tip. Details of the nozzle 13 will be described later.

  Examples of the pressurizer 15 include a piston pump pressurizer 15a shown in FIG. 2A and an auger pump pressurizer 15b shown in FIG. 2B. In the pressurizer 15a, the amount of liquid pushed out to the nozzle 13 is determined by the amount by which the piston 16 is pushed down. In the pressure supplier 15b, the amount of liquid pushed out to the nozzle 13 is determined by the amount of rotation of the screw 21. 2A and 2B, a member denoted by reference numeral 17 is a liquid tank that supplies liquid to the pressure supply devices 15a and 15b (in other words, supplies liquid to the droplet discharge device 1). . In the present embodiment, a liquid obtained by mixing phosphor particles in a resin is stored in the liquid tank.

  The head driving unit 4 moves the droplet discharge head 3 in the X-axis direction (up and down direction) indicated by an arrow X and the Y-axis direction (left and right direction) indicated by an arrow Y. The table 5 has a surface on which a plate-like workpiece is placed and supports the workpiece. The table driving unit 6 moves the table 5 in the Z-axis direction (depth direction) indicated by the arrow Z.

  The dischargeability monitoring unit 19 monitors the dischargeability of the liquid from the nozzle 13 and performs calibration of the discharge amount from the droplet discharge head 3, nozzle cleaning, and the like so that an accurate amount is discharged. It is. The dischargeability monitoring unit 19 includes a first camera 7, a second camera 11, and a first analysis control unit 9.

  The first camera 7 photographs the tip of the nozzle 13 from the horizontal direction, and is composed of a CCD camera or the like. FIG. 3 shows the positional relationship among the first camera 7, the table 5, and the nozzle 13. In the first camera 7, the shooting direction 25 is orthogonal to the normal direction 27 of the surface on which the work of the table 5 is placed, and the tip portion of the nozzle 13 and its periphery are set as the shooting range. In addition, when it is difficult to arrange the first camera 7 so that photographing in the horizontal direction can be spatially performed, the deviation of the photographing direction 25 from the horizontal direction may be corrected by calculation.

  In FIG. 3, what is indicated by reference numeral 31 is a liquid spherical body formed at the tip of the nozzle 13 by the liquid inside the nozzle 13 being pushed out. When the spherical body 31 is separated from the tip of the nozzle 13, it becomes a droplet.

  The second camera 11 photographs the table 5 from above. The second camera 11 can shoot a pattern formed on the workpiece with the discharged liquid. Each imaging data of the first camera 7 and the second camera 11 is sent to the first analysis control unit 9.

  The first analysis control unit 9 obtains the volume of the spherical body 31 by analyzing the image data of the spherical body 31 formed at the tip of the nozzle 13 and the tip taken by the first camera 7, and based on the volume. Thus, the droplet amount from the droplet discharge head 3 is feedback-controlled to optimize (calibrate) the droplet amount.

  The first analysis control unit 9 also captures image data of the tip of the nozzle 13 photographed by the first camera 7 and image data of the droplet 31 formed on the tip of the nozzle 13 and the tip. Analysis is performed to determine the cleanliness of the nozzle 13 and determine whether or not nozzle cleaning is necessary. The first analysis control unit 9 cleans the nozzle 13 using a nozzle cleaning device when cleaning is necessary.

  As the nozzle cleaning device, a conventional cleaning mechanism such as a discard shot, air blow, or cleaning can be used.

  The dispersibility monitoring unit 10 monitors the dispersibility of the phosphor particles in the liquid and manages the liquid so that the chromaticity of the liquid falls within a desired chromaticity range. The dispersibility monitoring unit 10 measures the particle size distribution of the phosphor particles as a parameter indicating the dispersibility of the phosphor particles. The particle size distribution indicates the distribution of the diameter (particle diameter) of the phosphor particles, and the particle size quality of the phosphor particles and segregation during the discharge process can be detected from the particle size distribution. In the present embodiment, the particle size distribution is measured using both the image imaging method and the laser light scattering method, but only one of them may be used.

  Moreover, in this Embodiment, the dispersibility monitoring part 10 measures the chromaticity of a liquid as a parameter which shows the dispersibility of a fluorescent substance particle. In this embodiment, both the chromaticity (predicted value) obtained from the density and area ratio of the phosphor particles with respect to the volume of the liquid and the chromaticity (actually measured value) obtained from the excitation light of the phosphor particles are measured. Only one of them may be measured.

  The dispersibility monitoring unit 10 includes a preparation unit 2. As shown in FIG. 4, the preparation portion 2 is set with a sample 83 in which the liquid 70 is sandwiched between two transparent plates 81 and 82 and is thinned. The liquid 70 is a droplet dropped from the nozzle 13, a liquid in the liquid tank, or a liquid in the pressurized supply unit 15.

  The liquid (droplet) 70 is thinned to a thickness approximately equal to the maximum particle diameter of the contained particles by being sandwiched and spread between the transparent plates 81 and 82. For example, when the particles are phosphor particles, the gap is set to 100 μm or less. Such setting of the sample 83 to the preparation part 2 may be either automatic or manual.

  The dispersibility monitoring unit 10 is a member for detecting the dispersibility of the phosphor particles in the liquid, in addition to the third camera 12 and the second analysis control unit 18, a laser light source 28 (see FIG. 5), XY A scanner, a focusing lens, a photodetector 29 (see FIG. 5), a wavelength distribution detector, and the like are provided.

  The third camera 12 captures a thin layer of the liquid 70 sandwiched between two transparent plates above and below the preparation portion 2. The third camera 12 takes an image with focusing on a portion where the back surface of the lower transparent plate 82 and the thin layer are in contact with each other. When the particles contained in the liquid 70 are phosphor particles, the third camera 12 illuminates and shoots single-wavelength light excited by the phosphor particles. The imaging data of the third camera 12 is sent to the second analysis control unit 18. The second analysis control unit 18 measures the particle size distribution of the phosphor particles using an image imaging method based on the imaging data. In addition, when calculating | requiring the particle size distribution of a fluorescent substance particle using an image imaging method, it is not essential to make a liquid thin in the preparation part 2. FIG.

  In addition, the laser light source 28, the XY scanner, the focusing lens, the photodetector 29, and the like are used for the dispersibility monitoring unit 10 to measure the particle diameter of the phosphor particles using the principle of the particle counter used in the semiconductor wafer. It is a member. By measuring the particle size d, the particle size distribution can be measured, and by determining the particle size and number from the particle size distribution, the density and area ratio of the phosphor particles to the volume of the liquid can be calculated.

  As shown in the upper part of FIG. 5, the laser light source 28 and the XY scanner send laser light to a thin layer of the liquid 70 sandwiched between two transparent plates 81 and 82 of the preparation part 2 through a focusing lens. Irradiation and XY scanning are performed, and the photodetector 29 detects scattered light to generate a detection signal, which is output to the second analysis control unit 18. Based on the detection signal, the second analysis control unit 18 measures the particle diameter d by the length of the wavelength, and counts the number by the number of detections. The second analysis control unit 18 measures the particle size distribution of the phosphor particles based on the particle size / number.

  Since the liquid is thinned in the preparation portion 2, multiple scattering of light does not occur even if the viscosity of the liquid is high or the concentration of the phosphor particles is high, and the laser light scattering method is used. The particle size distribution can be measured with high accuracy.

  The wavelength distribution detector irradiates a single laser beam onto a thin layer of the liquid 70 sandwiched between two transparent plates 81 and 82 above and below the preparation portion 2, and when the irradiated light is excited by phosphor particles, The wavelength is detected separately. The detected wavelength data is output to the second analysis control unit 18. The relative emission intensity of the emission spectrum of the liquid is shown in the upper part of FIG. The second analysis control unit 18 measures the chromaticity (actual value) based on such wavelength data. A chromaticity diagram of measured values is shown at the bottom of FIG. Note that a luminance detection device may be used instead of the wavelength distribution detection device.

  Further, the dispersibility monitoring unit 10 obtains the chromaticity (predicted value) from the density of the phosphor particles with respect to the volume of the liquid and the area ratio. By knowing the particle size distribution (particle size distribution per unit area) of the phosphor particles and determining the particle size and the number thereof, the density and area ratio of the phosphor particles with respect to the volume of the liquid can be calculated. The density indicates the dispersion state of the phosphor particles. Therefore, it is preferable to measure the density in a time-series manner in a state where particles are mixed in a liquid and stirred, or what is discharged by the nozzle 13 of the droplet discharge device 1.

  For the calculation of the density / area ratio, data on the particle size distribution measured by the image imaging method can also be used. A chromaticity diagram of predicted values obtained by obtaining the density and area ratio of the phosphor particles from the particle size distribution by the laser light scattering method is shown in the lower part of FIG.

  The second analysis control unit 18 analyzes the image data captured by the third camera 12 and optimizes the dispersibility of the particles contained in the droplet discharge head 3 and the liquid tank 17. In the present embodiment, the dispersion state of the phosphor particles contained in the liquid in the liquid droplet ejection head 3 or the liquid tank 17 is measured, and a desired dispersion state is obtained using the liquid stirring mechanism. Details of the first and second analysis control units 9 and 18 will be described later.

  The liquid agitating mechanism 72 agitates and homogenizes the liquid inside the droplet discharge head 3. For example, in the case of the piston pump type pressurization supply device 15a shown in FIG. 2A described above, the liquid between the pressurization supply device 15a and the liquid tank 17 is different depending on the head structure for discharging the liquid droplets. A mechanism in which the flow path is taken in and out and stirred can be employed. Further, in the auger pump type pressure supply device 15b of FIG. 2B, a mechanism for rotating and stirring the screw 21 can be employed. Any mechanism capable of stirring the liquid inside the droplet discharge head 3 may be used. The liquid in the liquid tank 17 may be further stirred.

(Nozzle configuration)
Next, the nozzles of the droplet discharge head will be described with reference to FIGS. FIG. 7A is a cross-sectional view showing an example of the nozzle 13, and FIG. 7B is a cross-sectional view showing an example of the water repellent layer provided in the nozzle 13.

  As shown in FIG. 7A, the nozzle 13 has a funnel-like shape, and includes a liquid reservoir 33 that stores liquid and a discharge cylinder 35 that communicates with the lower side of the liquid reservoir 33. . The pressurization supply device 15 is connected to the upper side of the liquid reservoir 33, and the liquid storage space inside the pressurization supply device 15 and the liquid storage space of the liquid storage portion 33 communicate with each other.

  The nozzle 13 is provided with a water-repellent layer 37 on the surface thereof, that is, on the inner wall surface, the outer wall surface, and the distal end surface of the discharge cylinder portion 35. In other words, the entire surface of the nozzle 13 is covered with the water repellent layer 37.

The water repellent layer 37 is a fluorine-based water repellent layer. Here, an aluminum oxide (Al ₂ O ₃ ) layer 39 and a silicon oxide (SiO ₂ ) layer 38 are provided in this order on the wall surface 40 of the nozzle 13 as a base layer of the water repellent layer 37.

  The thickness of the water repellent layer 37 is, for example, 1 to 4 nm. The total thickness of the three layers of the water repellent layer 37, the aluminum oxide layer 39 as the underlayer, and the silicon oxide layer 38 is preferably suppressed to, for example, 25 nm or less. By setting the thickness of the three layers to 25 nm or less, a change in the inner diameter of the discharge cylinder portion 35 can be suppressed even after long-term use. More preferably, it is 20 nm or less.

(Nozzle manufacturing method)
Such a water repellent layer 37 can be formed by the following procedure. First, the nozzle 13 is installed in the chamber using a vapor phase growth method of organic molecules, and the wall surface 40 of the nozzle 13 is cleaned using oxygen plasma and activated. Next, the reaction gas is heated to 100 ° C. and vaporized, and this is introduced into a chamber heated to 55 ° C. in advance, and an aluminum oxide layer 39 is formed on the surface of the nozzle 13. Thereafter, the inside of the chamber is evacuated to 3 to 8 Pa, and the above cycle is repeated to form an aluminum oxide layer 39 of about 10 nm.

  Subsequently, in the same chamber, the upper surface of the aluminum oxide layer 39 is cleaned using oxygen plasma and activated. Then, the reaction gas is heated to 100 ° C. and vaporized, and introduced into a chamber heated to 55 ° C. in advance, and a silicon oxide layer 38 is formed on the aluminum oxide layer 39. Thereafter, the inside of the chamber is evacuated to 3 to 8 Pa, and the above cycle is repeated to form a silicon oxide layer 38 of about 10 nm.

  Subsequently, a fluorine-based water repellent film is formed over the entire area of the silicon oxide layer 38. Thereby, the water-repellent layer 37 made of a monomolecular film having a thickness of about 1 to 4 nm is formed.

  By forming such a water repellent layer 37, the liquid pushed out from the inside forms a spherical body 31 at the tip of the nozzle 13 as shown in FIG. It becomes a droplet by separating from the tip part of.

(Description of analysis control unit)
Next, the first analysis control unit 9 and the second analysis control unit 18 will be described with reference to FIGS.

  FIG. 8 is a functional block diagram of the first analysis control unit 9 and the second analysis control unit 18. As shown in FIG. 8, the first analysis control unit 9 and the second analysis control unit 18 share an image data processing unit 51. The first analysis control unit 9 includes an image data processing unit 51, a nozzle check unit 52, a volume detection unit 53, a volume error detection unit 54, a set pressure adjustment unit 55, a nozzle cleaning instruction unit 56, and an error display instruction unit 57. The second analysis control unit 18 includes an image data processing unit 51, a particle size distribution measurement unit 58, a chromaticity prediction unit 59, a chromaticity measurement unit 60, and a stirring instruction unit 61.

  The image data processing unit 51 performs necessary image processing on the image data photographed by the first to third cameras 7, 11, 12, extracts data necessary for analysis, and uses the data To output.

  The image data processing unit 51 extracts the respective contours of the liquid around the nozzle 13 and the nozzle 13 from the image data obtained by the first camera 7 photographing the tip of the nozzle 13, and the extracted contour data is extracted from the nozzle The data is output to the check unit 52 and the volume detection unit 53. When the spherical body 31 is formed at the tip of the nozzle 13, the outline of the spherical body 31 is also extracted.

  Further, the image data processing unit 51 outputs image data obtained by photographing the droplets thinned by the third camera 12 in the preparation unit 2 to the particle size distribution measurement unit 58.

  The nozzle check unit 52 determines whether there is an abnormality in the nozzle 13 based on the contour data of the nozzle 13 and the surrounding liquid.

  FIG. 9A shows a photograph of a normal nozzle 13 taken in a state where no liquid is pushed out and a cross-sectional view thereof. In the normal nozzle 13, the liquid level inside the nozzle 13 is slightly above the opening, and no liquid adheres to the outer wall surface of the nozzle 13. In this case, the outline of the liquid is not extracted. On the other hand, FIG. 9B shows a photograph of an abnormal nozzle 13 taken in a state where the liquid is not pushed out and a cross-sectional view thereof. In the abnormal nozzle 13, the liquid protrudes from the opening at the tip of the nozzle 13 so as to cover the tip, and the liquid crawls up the outer wall surface of the nozzle 13 to a position above the opening of the nozzle 13. . In this case, the outline of the liquid covering the outer wall surface of the nozzle 13 is extracted.

  The nozzle check unit 52 determines normality / abnormality (determination of cleanliness) based on the image of the tip of the nozzle 13 taken in a state where the liquid is not pushed out and its surroundings. It is determined that the state shown in FIG. 10A is normal and the state shown in FIG. 10B is abnormal.

  Specifically, the contour data of the nozzle 13 and the liquid are stored as comparison references from an image obtained by photographing the tip of the nozzle 13 to which the maximum allowable amount of liquid has adhered. Then, each contour data of the image to be determined is compared with each contour data of the comparison reference, and when the liquid contour data exceeds the contour data of the comparison reference, it is determined that the nozzle is abnormal.

  In addition, the nozzle check unit 52 exceeds the allowable amount that the spherical body 31 crawls above the opening of the nozzle 13 based on the tip of the nozzle 13 taken in a state where the spherical body 31 is formed and the surrounding image. If it is raised, it is determined that the nozzle is abnormal.

  10A and 10B are sectional views of the nozzle 13 that is determined to be normal in a state where the spherical body 31 is formed. FIG. 10A shows a case where there is no problem with the nozzle 13, and a spherical body 31 having a high roundness is formed in the opening. FIG. 10B shows a state where there is a slight rise of the liquid above the opening of the nozzle 13 but within an allowable range.

  On the other hand, FIG. 10C shows a cross-sectional view of the nozzle 13 that is determined to be abnormal in a state where the spherical body 31 is formed. This is a state in which the liquid is rising so as to affect the volume of the spherical body 31 above the opening of the nozzle 13. The roundness of the spherical body 31 is also low.

  The nozzle check unit 52 is normal in the state shown in FIGS. 10A and 10B based on the image of the tip of the nozzle 13 taken in the state in which the spherical body 31 is formed and the surrounding area, and FIG. In the state shown in FIG.

  Specifically, as shown in FIG. 11, a threshold value for scooping from the opening position of the nozzle 13 is set. Then, it is determined that the nozzle is abnormal when the liquid scoops over the threshold from the liquid contour data. In the example of FIG. 11, the point sequence data portion of the contour data is abnormal and exceeds the threshold value for scooping.

  When determining that there is a nozzle abnormality, the nozzle cleaning instruction unit 56 notifies the nozzle cleaning instruction unit 56 and the error display instruction unit 57 that there is a nozzle abnormality.

  The volume detection unit 53 calculates and detects the volume of the spherical body 31 based on the contour data of the spherical body 31.

Specifically, the volume detection unit 53 calculates the distance L1 from the upper end to the lower end of the spherical body 31 based on the contour data of the spherical body 31, sets the half value as the radius r, and calculates the formula “4 / By calculating using “3πr ³ ”, the volume of the spherical body 31 is calculated. When the volume detection unit 53 cannot calculate the diameter L1 of the spherical body 31 based on the contour data that should have taken the spherical body 31, the volume detection unit 53 determines that the ejection performance is poor and notifies the error display instruction unit 57 that the discharge performance is poor. To be notified.

  Here, the configuration for calculating the volume using the formula of the volume of the sphere is illustrated. However, the present invention is not limited to this. A table in which contour data and a volume corresponding to the contour data are associated with each other is stored, and the extracted contour data is compared with the contour data of the table. The configuration may be such that the volume of the contour data is obtained.

  The volume error detection unit 54 detects a difference between the volume (actual droplet amount) of the spherical body 31 calculated by the volume detection unit 53 and the theoretical droplet amount. The theoretical droplet amount is the amount of liquid (volume) that the pressurization supply device 15 has pushed out the liquid to the nozzle 13 in forming the spherical body 31.

  Specifically, the volume error detection unit 54 compares the volume of the spherical body 31 calculated by the volume detection unit 53 with the theoretical droplet amount, and calculates the calculated volume of the spherical body 31 and the theoretical droplet amount. Is calculated as a volume error.

  Based on the volume error detected by the volume error detector 54, the set pressure adjuster 55 determines whether or not the set pressure of the pressurizer 15 needs to be adjusted. Feedback control is performed to adjust 15 theoretical droplet amounts.

  The nozzle cleaning instruction unit 56 instructs the nozzle cleaning device 71 to clean the nozzle 13 when notified by the nozzle check unit 52 that there is a nozzle abnormality.

  When the nozzle check unit 52 notifies that there is a nozzle abnormality, the error display instruction unit 57 causes the display unit 73 to display a message informing that nozzle cleaning is being performed. In a configuration in which nozzle cleaning is not automatically performed, a message requesting nozzle cleaning may be displayed, or a lamp for prompting nozzle cleaning may be turned on.

  In addition, when the ejection performance failure is notified from the volume detection unit 53, the error display instruction unit 57 causes the display unit 73 to display a message or the like informing that the ejection performance is defective. For example, a lamp for notifying that the discharge performance is defective may be turned on.

  As described above, the particle size distribution measuring unit 58 in the second analysis control unit 18 measures the particle size distribution by the image imaging method and the particle size distribution by the laser light scattering method.

  12 (a) and 12 (b) show images obtained by photographing the thinned liquid. 12 (a) and 12 (b) are images of the same part of the thinned liquid, while FIG. 12 (a) is an image taken with ordinary light, and FIG. 12 (b) is a fluorescence image. Photographed by illuminating single-wavelength light excited by body particles. The particle size distribution measurement unit 58 uses the image of FIG. 12B when measuring the particle size distribution by the image imaging method.

  An X-Y scan is performed on the image within the field-of-view size obtained by photographing the thinned droplet, and the size X (maximum value and minimum value in the X direction) and size of each phosphor particle included in the image Information on Y (maximum value and minimum value in the Y direction) and the number of phosphor particles is acquired. Then, from the acquired information and the number of pixels of the imaging element, the area of the phosphor particles in the image within the visual field size is obtained, and the particle size distribution is measured.

  Further, the particle size distribution measuring unit 58 measures the particle size distribution by the laser light scattering method described above. A laser light source 28 and an XY scanner are used to focus a laser beam on a thin layer of liquid 70 sandwiched between two upper and lower transparent plates 81 and 82 of the preparation portion 2 as shown in the upper part of FIG. And XY scan is performed, and the light detector 29 detects the scattered light and generates a detection signal.

  The particle size distribution measuring unit 58 measures the particle size d of the phosphor particles based on the length of the wavelength of the detection signal, and measures the number of phosphor particles based on the number of detections. The particle size distribution measuring unit 58 performs XY scanning, acquires information on the particle size and the number corresponding to the wavelength of the phosphor particles within the field size, and measures the particle size distribution of the phosphor particles.

  Based on the particle size distribution (particle size distribution per unit area) of the phosphor particles, the chromaticity prediction unit 59, in other words, by determining the particle size per unit area and the number thereof, the volume of the liquid is calculated using these. The density and area ratio of the phosphor particles with respect to are calculated. Since the specific gravity of the phosphor particles is known, the density of the phosphor particles can be obtained. The phosphor particles are treated as spheres. The chromaticity prediction unit 59 obtains a chromaticity prediction value from the obtained density and area ratio (see the chromaticity diagram shown in the lower part of FIG. 5).

  Note that the chromaticity prediction unit 59 may predict the chromaticity based on the particle size distribution obtained by the image imaging method.

  The chromaticity measurement unit 60 irradiates a thin layer of the liquid 70 sandwiched between the upper and lower transparent plates 81 and 82 with a single laser beam to excite phosphor particles. The chromaticity measurement unit 60 measures chromaticity (measured value) based on data obtained by detecting the wavelength of light excited by the phosphor particles with the wavelength distribution detector (lower part of FIG. 6). Refer to the chromaticity diagram shown in

  The chromaticity prediction unit 69 and the chromaticity measurement unit 60 determine whether the dispersibility of the phosphor particles in the liquid is good or not based on the estimated chromaticity range or the actually measured chromaticity. As described above, when the chromaticity is out of the desired chromaticity coordinates based on the range of the chromaticity coordinates of the predicted values shown in the lower part of FIG. 5, the fluorescence in the liquid enters the desired chromaticity coordinates. It is necessary to adjust the dispersion state of the body particles. Similarly, when the chromaticity coordinates are out of the desired chromaticity coordinates based on the actually measured chromaticity coordinates shown in the lower part of FIG. 6, the phosphor particles in the liquid enter the desired chromaticity coordinates. It is necessary to adjust the distributed state.

  When the total content of the phosphor particles relative to the resin is adjusted when the liquid stored in the liquid tank 17 is prepared, the dispersibility of the phosphor particles relative to the resin may be adjusted.

  If a droplet is collected in a liquid stirring state in advance and it is determined whether or not the chromaticity coordinate is at a predetermined coordinate by the above method, the change in chromaticity after the droplet is discharged can be managed. In other words, the chromaticity prediction unit 69 and the chromaticity measurement unit 60 adjust the dispersibility of the phosphor particles so that the chromaticity of the liquid falls within a predetermined range based on the measured chromaticity range or chromaticity coordinates. Control. Specifically, in the droplet discharge device 1 of the present embodiment, the chromaticity prediction unit 69 and the chromaticity measurement unit 60 are poorly dispersed in order to stir the liquid using the liquid stirring mechanism 72. If it is determined, the stirring instruction unit 61 is notified of it.

  When the stirring instruction unit 61 is notified of a poor dispersion state from the chromaticity prediction unit 69 and the chromaticity measurement unit 60, the liquid phosphor particles in the liquid droplet ejection head 3 are uniformly dispersed in the liquid stirring mechanism 72. Instruct liquid agitation to

  FIG. 13 shows a flow of calibration processing in the droplet discharge device 1. First, a droplet volume measurement process for measuring the volume of a droplet is performed (S1). Details of S1 will be described later using S10. Next, a liquid dispersibility determination process for determining the dispersibility of the liquid is performed (S2). Details of S2 will be described later using S11. When S1 and S2 are completed, the process proceeds to S3.

  In S3, it is determined whether or not it is determined in the droplet volume measuring process in S1 that there is a defective ejection performance. If YES, the calibration process is terminated. On the other hand, if NO, the process proceeds to S4.

  In S4, it is determined whether or not it is determined that there is a nozzle abnormality in the droplet volume measurement process in S1, and if YES, the process proceeds to S5 to perform nozzle cleaning, and then proceeds to S6. On the other hand, if NO, skip S5 and proceed to S6.

  In S6, in the droplet volume measurement process in S1, it is determined whether or not it is determined that the set pressure of the pressurization supply unit 15 needs to be adjusted. If YES, the process proceeds to S7 and the set pressure is adjusted. After that, the process proceeds to S8. On the other hand, if NO, skip S7 and proceed to S8.

  In S8, it is determined in the liquid dispersibility determination process in S2 whether or not it is determined that the liquid is poorly dispersed. If YES, the process proceeds to S9 and the liquid is stirred, and then the calibration process is performed. Exit. On the other hand, if NO, step S9 is skipped and the calibration process is terminated.

  FIG. 14 shows the flow of the droplet volume measurement process. First, the first camera 7 takes a picture of the tip of the nozzle 13 and its surroundings in a state where no pressure is applied to the pressure supply unit 15, that is, a state where no liquid is pushed out to the nozzle 13 (S11). The first analysis control unit 9 acquires data of the image captured in S11 (S12), and acquires nozzle 13 and liquid contour data (S13).

  Next, the first analysis control unit 9 determines whether there is an abnormality in the nozzle 13 based on the amount of liquid adhering to the nozzle 13 based on the contour data acquired in S13 (S14). If there is an abnormality in S14, the droplet volume measurement process is terminated, and the process proceeds to S15 only when there is no abnormality.

  In S <b> 15, the pressurizer 15 applies a set pressure that pushes the theoretical droplet amount to the nozzle 13. On the other hand, the 1st camera 7 image | photographs the front-end | tip part of the nozzle 13, and its circumference | surroundings (S16). The first analysis control unit 9 acquires image data showing the spherical body 31 immediately before the projection from the image data captured in S16 (S17), and acquires the nozzle 13 and liquid contour data (S18).

  Next, the first analysis control unit 9 determines whether the nozzle 13 has an abnormality based on whether or not the liquid rising from the opening at the tip of the nozzle 13 exceeds the threshold value for rising based on the contour data acquired in S18. Whether or not there is is determined (S19). If there is an abnormality in S19, the droplet volume measurement process is terminated, and the process proceeds to S20 only when there is no abnormality.

  In S20, the analysis / control unit 9 calculates a distance L1 from the upper end to the lower end of the spherical body 31 based on the outline data of the spherical body 31, and in S21, the volume of the spherical body 31 is set with a radius r as a half value of L1. calculate.

  Next, the analysis / control unit 9 compares the volume of the spherical body 31 calculated in S21 with the theoretical droplet amount of the set pressure applied in S15, and calculates the difference as a volume error (S22). Next, the analysis / control unit 9 determines whether or not the set pressure of the pressurization feeder 15 needs to be adjusted based on the volume error calculated in S22, and ends the droplet volume measurement process.

  In FIG. 14, the volume measurement process is configured to calculate the distance L1 of the spherical body 31 and the subsequent volume once to adjust the set pressure of the pressure supply device 15, but calculate the volume multiple times. However, the average value may be used.

  FIG. 15 shows the flow of the liquid dispersibility determination process. First, the droplet discharge head 3 discharges droplets onto the lower transparent plate of the preparation unit 2 (S32). Next, the preparation part 2 makes the upper transparent plate overlap the lower transparent plate and sandwiches the droplets to make a thin layer (S32).

  The third camera 12 photographs the thinned droplet from the lower transparent plate 82 side (S33). The particle size distribution measuring unit 58 of the second analysis control unit 18 acquires the data of the image taken in S33 (S34), and measures the particle size distribution of the phosphor particles in the liquid by the image imaging method (S35).

  Next, the particle size distribution measuring unit 58 of the second analysis control unit 18 irradiates the laser beam, and performs XY scanning on the thinned droplet from the lower transparent plate 72 side (S36). The particle size distribution of the phosphor particles in the liquid is measured by the light scattering method (S37).

  Next, the chromaticity prediction unit 59 of the second analysis control unit 18 calculates a predicted value of chromaticity from the area ratio obtained from the data obtained in S34 or S36 and the density of the phosphor particles with respect to the volume of the liquid. Calculate (S38).

  Next, the chromaticity measurement unit 60 of the second analysis control unit 18 measures the chromaticity. The second analysis control unit 18 determines the quality of the dispersibility of the phosphor particles in the liquid based on the measurement and calculation results of the particle size distribution measurement unit 58, the chromaticity prediction unit 59, and the chromaticity measurement unit 60 (S40). .

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Droplet discharge device 3 Droplet discharge head 5 Table 7 1st camera 9 1st analysis control part 12 3rd camera 10 Dispersibility monitoring part 13 Nozzle 15 Pressure supply device 18 2nd analysis control part 19 Discharge property monitoring part 31 Spherical body 52 Nozzle check part
53 Volume detector (volume calculator)
54 Volume error detector (feedback controller)
55 Set pressure adjustment unit (feedback control unit)
56 Nozzle cleaning instruction section (nozzle cleaning section)
57 Error display instruction unit 58 Particle size distribution measurement unit 59 Chromaticity prediction unit 60 Chromaticity measurement unit 61 Agitation instruction unit 71 Nozzle cleaning device (nozzle cleaning unit)
72 Liquid stirring mechanism (dispersibility adjusting part)

Claims (5)

A droplet amount measuring method for measuring a droplet amount discharged from a nozzle,
Photograph the droplet and nozzle formed just before the separation formed at the tip of the nozzle, detect the amount of droplet rising to the outer periphery of the nozzle based on the captured image data, and detect the droplet just before separation A pass / fail judgment step for judging pass / fail;
A droplet amount measuring method comprising: a volume calculating step of calculating a volume of a droplet determined to be good in the pass / fail determination step based on image data used for detecting the amount of scooping . In a liquid droplet ejection apparatus that ejects liquid droplets from a nozzle by extruding liquid from a pressure supply unit connected to the nozzle,
An imaging unit that images the nozzle formed immediately before separation and the nozzle formed at the tip of the nozzle;
A pass / fail judgment unit for detecting the amount of liquid droplets rising to the outer periphery of the nozzle based on the image data photographed by the photographing unit and judging the quality of the liquid droplet just before separation;
A volume calculation unit that calculates the volume of the liquid droplet determined to be good by the quality determination unit based on the image data used to detect the amount of scooping;
A droplet discharge apparatus comprising: a feedback control unit that adjusts a liquid push-out amount in the pressurization supply unit based on a volume of the droplet calculated by the volume calculation unit.   The droplet discharge device according to claim 2, further comprising a nozzle cleaning unit that cleans a nozzle when the pass / fail determination unit determines NO. A particle size distribution measuring method for measuring a particle size distribution of particles contained in a liquid using a laser light scattering method,
A thinning step of sandwiching the liquid between the transparent plates and thinning to a thickness of the diameter of the particles having the largest diameter among the particles contained in the liquid;
A particle size distribution measuring method comprising: a particle size distribution measuring step for measuring a particle size distribution based on scattered light obtained by irradiating a laser beam to a thin layered liquid and scanning. In a liquid droplet ejection apparatus that ejects liquid droplets from a nozzle by extruding liquid from a pressure supply unit connected to the nozzle,
Laser is irradiated to the liquid that is sandwiched between the transparent plates and thinned to the diameter of the largest particle among the particles contained in the liquid and scanned, and the particle size distribution is determined based on the obtained scattered light. A particle size distribution measuring unit to be measured;
A chromaticity prediction unit that predicts the chromaticity of the liquid by calculating the density and area ratio of the phosphor particles in the liquid based on the particle size distribution measured by the particle size distribution measurement unit. Droplet discharge device.

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