JP6868844B2 - Droplet measurement method - Google Patents

Description

The present invention relates to a droplet measuring method and a droplet measuring device.

As a method for manufacturing devices such as color filters for liquid crystal displays and organic EL displays, for example, a liquid material containing a functional material is ejected as droplets from a plurality of nozzles by an inkjet method, and a film of the functional material is applied to a printing object. A method for manufacturing a panel is known.

In this case, it is an important process to acquire the correspondence between the setting of the control device that controls the ejection amount of the droplet and the actual ejection amount of the droplet, and control the ejection amount of the droplet to a constant value. .. This is because if the amount of droplets discharged is not uniform, the film thickness of the functional material will be different, which will lead to a defect of the device. For example, in the case of a color filter or an organic EL display, the difference in film thickness is observed as color unevenness or brightness unevenness.

In order to check the actual discharge amount from the nozzle, when an ink containing a polymer-based solute is used, for example, after the ink is discharged / applied to a transparent substrate such as glass and the solvent is dried. , At least a part of the droplets were measured by a reference device for measuring the shape of the droplets using a measuring device such as the optical interference principle or the cofocal principle, which can accurately measure the shape even if it takes a long time to measure. The accurate inclination of the surface of the droplet on the three-dimensional coordinate system is obtained, and further, the accuracy of the surface of the droplet on the three-dimensional coordinate system is obtained based on the brightness information obtained by imaging the droplet in the imaging step. A correspondence table showing the correspondence between the inclination and the brightness information is created, and the brightness of the droplet to be measured from time to time is measured only by the imaging step that can measure in a short time, and all the obtained droplets are obtained. There is known a method of obtaining the volume or surface shape of a droplet by using the brightness information of the above and the corresponding table.

Japanese Unexamined Patent Publication No. 2015-125125

In the method of calculating the volume or the surface shape from the luminance information of the droplet as described above, the amount of light reflected from the surface of the droplet to be measured is an important factor for determining the measurement accuracy.

This is because the amount of light reflected from the surface of the droplet has a strong correlation with the inclination angle of the surface of the droplet, and this correlation is used to calculate the shape of the droplet to be measured from the amount of light reflected from the surface of the droplet. To do.

However, depending on the relationship between the shape of the droplet to be measured and the thickness of the transparent substrate, the shape of the droplet to be measured behaves like a lens, so that the light transmitted through the droplet to be measured and reflected on the back surface of the transparent substrate. May collect light near the surface of the droplet to be measured. When the light reflected on the back surface of the transparent substrate is focused near the surface of the droplet, the brightness distribution of the amount of light reflected from the surface of the droplet, which has a strong correlation with the shape of the droplet, cannot be accurately obtained, and the calculation accuracy of the shape of the droplet cannot be obtained. Get worse.

Note that the light reflected on the back surface of the transparent substrate may have a brightness distribution in which the brightness is higher toward the center of the droplet and lower toward the outer periphery of the droplet, similar to the light reflected from the surface of the droplet. By overlapping two different luminance distributions, the correlation with the droplet shape is weakened, and the accuracy of calculating the droplet shape from the luminance distribution is lowered.

That is, the problem to be solved by the present invention is to obtain a luminance distribution of only the amount of light reflection from the surface of the droplet, which changes according to the shape of the droplet to be measured.

The droplet measuring apparatus of the present invention comprises a translucent sample substrate on which droplets to be measured are formed on the surface, a measurement table holding the sample substrate, and the liquid by irradiating the sample substrate with light. The volume or surface shape of the droplet based on the image pickup unit that captures the droplet and measures the amount of reflected light from the sample substrate and the droplet, and the brightness information of the amount of reflected light measured by the imaging unit. The thickness of the sample substrate is larger than the focal distance of the droplet, including the measurement control unit for obtaining the above and the space portion formed on the surface of the measurement table so that the back surface of the sample substrate does not come into contact with each other. It is characterized by.

Further, in the droplet measuring method of the present invention, the droplet is placed on a translucent sample substrate on which the droplet to be measured is formed on the surface, and the droplet is placed on a measurement table in which a space formed by a recess is formed on the surface. The position on the back surface side of the sample substrate is set so as to coincide with the space portion, and the droplet formed on the sample substrate set on the measurement table is irradiated with light and imaged by the imaging unit to obtain the sample substrate. The amount of reflected light from the droplet is measured in a state where the thickness of the sample substrate is larger than the focal distance of the droplet, and the volume or surface shape of the droplet is determined based on the amount of reflected light measured by the imaging unit. It is characterized by seeking.

Further, in the droplet measuring method of the present invention, a translucent sample substrate is set on a measuring table in which a space formed by a recess is formed on the surface, and a head having a nozzle to be evaluated is used to obtain the measurement table. A functional material is ejected toward the position of the space portion to form a droplet on the surface of the sample substrate, and the droplet of the sample substrate is imaged by an imaging unit to be taken from the sample substrate and the droplet. The amount of reflected light is measured, and the droplets formed on the sample substrate set on the measurement table are irradiated with light and imaged by an imaging unit to determine the amount of reflected light from the sample substrate and the droplets. The thickness of the sample substrate is measured in a state where the thickness is larger than the focal distance of the droplet, and the volume or surface shape of the droplet is obtained based on the amount of reflected light measured by the imaging unit to evaluate the nozzle of the head. , Characterized by.

According to this configuration, the light reflected on the back surface of the sample substrate can be regarded as parallel light near the surface of the droplet, and only the reflected light from the surface of the droplet, which changes according to the inclination of the surface of the droplet. Brightness distribution can be obtained.

Therefore, when the droplet is imaged, the luminance information and the inclination information can be easily associated with each other, and the volume or surface shape of the droplet can be accurately obtained at high speed from the luminance information of the droplet. As a result, the measurement time for the volume and shape of the droplet can be shortened, and the measurement accuracy can be improved.

A panel manufacturing device equipped with a droplet ejection device that ejects and applies ink of a functional material to an object to be printed, and a droplet measuring device that measures droplets in advance so that the ejection amount of this ink approaches a target value. Diagram Overall flow chart of the droplet measuring device of the present embodiment Enlarged sectional view of the sample substrate Enlarged plan view of the sample substrate on which the droplets to be measured are formed. Configuration diagram of the imaging unit Explanatory drawing showing the path of light when imaging a droplet Simulation explanatory diagram showing the behavior of light assuming a droplet as an ideal lens Simulation explanatory diagram showing the behavior of the passing light when the droplet shape is modeled Cross-sectional view of the measurement table on which the sample substrate is set Flow chart of droplet evaluation process

Hereinafter, the droplet measuring method of the present invention will be described based on the embodiment.

(Embodiment 1)
FIG. 1 shows a panel manufacturing apparatus provided with a droplet measuring apparatus that implements the droplet measuring method of the present invention. The panel manufacturing apparatus includes a droplet ejection device 1, a droplet measuring apparatus 2, a decompression chamber 3, and a droplet shape measuring apparatus 4.

The decompression chamber 3 is used to dry the applied droplets. The droplet measuring device 2 obtains the volume or surface shape of the droplet 30 at high speed based on the brightness information obtained by imaging the droplet 30 ejected onto the sample substrate 19 by the droplet ejection device 1. The result is fed back to the droplet ejection device 1 so as to approach the target state for the subsequent manufacturing operation.

The droplet shape measuring device 4 provided separately from the droplet measuring device 2 is a reference device used for creating a correspondence table between the droplet shape and the brightness information obtained by the droplet measuring device 2, and the measurement takes time. It is a measuring device of the optical interference principle, the cofocal principle, and the AFM principle that can accurately measure the shape even if it is applied. In this embodiment, a measuring device using optical interference is used.

The droplet shape measuring device 4 may be mounted on the droplet ejection device 1, the droplet measuring device 2, or the droplet ejection device 1 or the droplet. It may not be mounted on the measuring device 2 but may be installed alone outside the device.

<Drop discharge device 1>
In the droplet ejection device 1 that manufactures devices such as color filters for liquid crystal displays and organic EL displays, a liquid material containing a functional material is directed from a line head 6 of a head unit 5 toward a print target 7 by an inkjet method. The panel is manufactured by discharging it as a drop.

The print object 7 is set on the production table 8 at a position vertically downward of the head unit 5. The production table 8 is attached to a stage 9 having a drive system and is conveyed in the X direction. A gate-shaped gantry 12 composed of a pair of legs 10, legs 10 and a support 11 attached above the legs 10 is fixed on the stage 9.

A support base 13 having an elevating shaft in the vertical direction (see the Z-axis direction in FIG. 1) is connected to the front surface of the gantry 12 so as to be movable in the vertical direction. A head unit 5 is arranged on the support base 13.

The head unit 5 includes a distribution tank 14 and a line head 6. The gap between the print object 7 and the line head 6 is adjusted by moving up and down in the vertical direction Z.

The line head 6 includes a plurality of droplet ejection module heads 15 including a plurality of nozzles (not shown) for ejecting ink and a piezoelectric actuator (not shown) corresponding to each nozzle.

The print control unit 16 supplies electric power and a control signal for each head to each droplet ejection module head 15, and also supplies a control signal to the drive shafts in the X and Z directions. The print control unit 16 may include a corresponding table creation unit 17 and a volume calculation unit 18, which will be described later.

In this way, the line head 6 includes the droplet ejection module head 15 arranged over the entire width of the print object 7, and during the printing operation, the print control unit 16 conveys the print object 7 in the X direction. By ejecting droplets from the line head 6 at a predetermined timing according to the control signal from the printer, it is possible to form a desired image over the entire width of the print object 7.

<Droplet measuring device 2>
The sample substrate 19 measured by the droplet measuring device 2 is set in the droplet discharging device 1 and coated with a functional material by the line head 6. The sample substrate 19 is translucent, and here, a material such as transparent glass is used.

The sample substrate 19 can be used in either the case where the print target 7 coated with the desired functional material is used as it is or the case where the print target 7 is cut and used. Then, a case where a printed object 7 is divided and used will be described as an example.

The sample substrate 19 is set on the measurement table 21 at a position in the vertical direction of the imaging unit 20.

The method for transporting the sample substrate 19 in the droplet measuring device 2 is preferably automatic transport by a robot, but manual transport may also be used. In this embodiment, the automatic robot performs the steps up to the process of cutting the print object 7 created by the droplet ejection device 1 to create the sample substrate 19, and the sample substrate 19 having a smaller size is used as the droplet measuring apparatus 2. The transport set in is performed manually.

The measurement table 21 on which the sample substrate 19 is set is attached to the stage 22 having a drive system and conveyed in the X direction. A gate-shaped gantry 23 is fixed on the stage 22. It is desirable that the gantry 23 has a drive system and has a mechanism capable of moving the imaging unit 20 in the Y direction and the Z direction.

It should be noted that the mechanism may not be such that the stage 22 is conveyed in the X direction, but the mechanism may be such that the stage 22 is fixed and the imaging unit 20 is conveyed in the X direction. According to this configuration, the operating range of the droplet measuring device 2 can be reduced.

The droplet measuring device 2 has a gantry 24 on which a stage 22 having a drive system is mounted. It is desirable that the gantry 24 is equipped with a vibration isolator in order to exclude vibration from the outside. As the vibration isolation table, an active vibration isolation table that operates actively in response to vibration may be used, or a passive vibration isolation table that operates passively in response to vibration may be used.

The droplet measuring device 2 includes a measurement control unit 25. The measurement control unit 25 also supplies a control signal to the drive shafts in the X, Y, and Z directions, and also supplies a control signal to the image pickup unit 20 used for measuring droplets. The measurement control unit 25 may include a corresponding table creation unit 26 and a volume calculation unit 27.

It is desirable that the measurement control unit 25 is connected to the print control unit 16 mounted on the droplet ejection device 1 through a network or the like, and the image captured by the imaging unit 20 and the droplet calculated using the image. It is desirable to have a mechanism that can transfer data such as volume or surface shape.

According to this configuration, based on the droplet volume derived by the measurement control unit 25 of the droplet measuring device 2, the driving voltage and the like when the ink is ejected by the droplet ejection device 1 are set by the respective droplet ejection module heads. It is possible to supply power and a control signal for each head to 15.

The imaging unit 20 will be described later with reference to FIG.

<Droplet measurement system>
Next, a droplet measurement system that implements the droplet measurement method of the present invention will be described with reference to FIG.

This droplet measurement method is performed in a substrate preparation step S10 performed by using a spin coating or a die coating device as a preliminary preparation, a ejection / coating step S20 performed by the droplet ejection device 1, and a droplet ejection device 1 and a decompression chamber 3. The drying step S30, the imaging step S40 performed by the droplet measuring device 2, the shape measuring step S50 performed by the droplet shape measuring device 4, and the corresponding table creating step S60 performed by the print control unit 16 or the measurement control unit 25. A droplet evaluation step S70 performed by the print control unit 16 or the measurement control unit 25 is provided.

<Board making process S10>
First, with reference to FIG. 3, a substrate making step S10 performed by using a spin coating, a die coating device, or the like as a preliminary preparation will be described.

The sample substrate 19 is composed of a support substrate 28 and a polymer film 29.

For the support substrate 28, for example, glass can be used. The polymer film 29 is formed by dissolving, for example, a resist material used for forming a light emitting layer of an organic EL display in an organic solvent, applying it to a support substrate 28 by spin coating, die coating, or the like, and drying it. The material to be the polymer film 29 is a photosensitive material made of polyimide or acrylic resin. And fluorine may be contained in this. The resin material containing fluorine is generally highly translucent, and is not particularly limited as long as it has a fluorine atom in at least a part of the repeating units of the polymer repeating unit. Examples of the resin containing a fluorinated compound include a fluorinated polyolefin resin, a fluorinated polyimide resin, and a fluorinated polyacrylic resin. The film thickness is usually 0.1 to 3 μm, and particularly preferably 0.8 to 1.2 μm. Hereinafter, the case where a photosensitive material made of polyimide or acrylic resin is used as an example of the polymer film 29 will be described.

By using a fluorine-containing polymer material as the material of the polymer film 29, the polymer film 29 has a water-repellent function.

Here, the water repellency may be too high when the fluorine film is formed on the surface. In such a case, since the desired contact angle cannot be obtained after applying / drying the ink, the polymer film 29 of the sample substrate 19 is irradiated with UV light (ultraviolet light) to partially bond fluorine. The water repellency of the sample substrate 19 can be controlled by cutting the sample substrate 19 in a targeted manner.

<Discharge / coating process S20>
Next, in the ejection / coating step S20 performed by the droplet ejection device 1, a liquid material containing a functional material is ejected from a line head 6 having a plurality of nozzles to be evaluated to form droplets on the sample substrate 19. The discharge / coating process will be described.

FIG. 4 shows the sample substrate 19 and the droplet coating pattern formed on the sample substrate 19.

On the sample substrate 19, there are a droplet 30 and a dummy droplet 31 for keeping the atmosphere of the volume measurement droplet sample at the time of drying constant.

The dummy droplet 31 has a role of keeping the solvent atmosphere of the droplet 30 constant during drying and keeping the contact angle α of the droplet 30 within a constant range.

The number of dummy droplets 31 varies depending on the solvent of the ink used. For example, when the ink solvent is anisole, it is desirable to surround the outer periphery of the droplet 30 with dummy droplets having about 1 to 10 laps. In the embodiment, two round dummy droplets 31 are arranged around the droplet 30.

<Drying process S30>
In the drying step S30, although it depends on the physical characteristics of the solvent of the ink used, for example, when the solvent is anisole, the ink is dried in a temperature range of 23 ° C. or higher and 60 ° C. or lower in a reduced pressure atmosphere. According to the physical properties of the solvent of the ink to be used, for example, it is left on the production table 8 for a predetermined time and naturally dried in the air atmosphere, and then the ink is naturally dried in the air pressure atmosphere at an appropriate timing in the pressure reducing chamber 3 in the pressure reducing atmosphere. good. According to this configuration, the droplet 30 can be controlled into a desired shape.

<Imaging process S40>
In the imaging step S40, the image pickup unit 20 images the droplet 30 created through the drying step S30.

The overall configuration of the imaging unit 20 is shown in FIG. The image pickup unit 20 includes a light source 32, a camera 33 and a lens 34, a jig 35 that holds the camera 33 and the lens 34, a drive mechanism 37 that drives them in the X direction along the scanning axis 36, and a focus adjustment. It has a Z-direction drive mechanism 38 for the purpose.

The camera 33 and the lens 34 take an image of the droplet 30 applied to the sample substrate 19 while moving along the scanning axis 36 direction. The image data of the droplet sample is sent to the corresponding table creation unit 26 and the volume calculation unit 27 provided in the measurement control unit 25.

The camera 33 may be equipped with an area sensor or a line sensor, but in the present embodiment, a camera equipped with a line sensor is used. The number of pixels and the pixel size may be selected according to the object to be imaged, but in the present embodiment, the number of pixels in the width direction is 4096 and the pixel size is 2 μm. The magnification and NA of the lens 34 are selected according to the shape of the droplet to be imaged. In this embodiment, a lens having a magnification of 5 times and an NA of about 0.1 was used.

It is desirable to use a telecentric lens for the lens 34 so that the influence of focus is relatively small. In order to avoid the influence of the tilt of the optical axis, it is desirable to use a coaxial epi-illumination lens for illumination.

A recess 44 is provided in the measurement table 21 in order to prevent unevenness of the reflected light from the upper surface of the measurement table 21 due to dirt on the upper surface of the measurement table 21 or unevenness of the treatment film. More specifically, as shown in FIG. 9, the upper surface of the measurement table 21 is prevented so that the back surface of the sample substrate 19 at the position of the droplet 30 formed on the sample substrate 19 does not come into contact with the upper surface of the measurement table 21. A recess 44 opened in is formed in the measurement table 21. In the inside of the measurement table 21, a suction path 45 opened on the upper surface of the measurement table 21 is formed separately from the recess 44, and the sample substrate 19 set in the measurement table 21 is sucked from the suction path 45. It is attracted to and held on the upper surface of the measurement table 21. According to this configuration, it is possible to prevent ambient light from entering due to dirt on the upper surface of the measurement table 21 or unevenness of the treatment film.

<About the light path in the imaging step S40>
FIG. 6 shows the path of light when the droplet 30 ejected from the line head 6 is imaged on the sample substrate 19. Although the arrows in FIG. 6 conceptually indicate the light path, they do not indicate the actual light traveling path.

The parallel light 39 emitted from the light source 32 is divided into light 40 reflected on the surface of the droplet 30 and light 41 refracted and penetrated into the droplet. The light 42 reflected from the interface between the droplet 30 and the polymer film 29 and the light 50 reflected from the interface between the polymer film 29 and the support substrate 28 are refracted by the droplet 30 and the polymer film 29 and the support substrate 28. By reducing the difference in the rates, the amount of light becomes smaller than that of the lights 40 and 41, so this is ignored in the present embodiment.

Since the light 40 reflected on the surface of the droplet 30 has a correlation with the inclination of the droplet 30, the shape of the droplet 30 can be calculated based on this amount of light. That is, the light 40 reflected on the surface of the droplet 30 tends to be brighter because the inclination becomes smaller toward the center of the droplet 30, and becomes darker because the inclination becomes larger toward the outer periphery of the droplet 30.

However, depending on the relationship between the thickness of the droplet 30 and the thickness of the sample substrate 19, the shape of the droplet to be measured behaves like a lens, so that the light that has passed through the droplet to be measured and reflected on the back surface of the transparent substrate can be generated. It may be focused near the surface of the droplet 30 to be measured. When the light reflected on the back surface of the sample substrate 19 is focused near the front surface of the droplet 30, the brightness distribution of the amount of light reflection from the surface of the droplet, which has a strong correlation with the shape of the droplet, cannot be accurately obtained, and the shape of the droplet. The calculation accuracy of is deteriorated. As a result, it is preferable that the thickness of the sample substrate 19 is larger than the focal length of the droplets because the contrast of light is lowered.

Below, in addition to the light 40 reflected on the front surface of the droplet 30 as described above, the light 43 transmitted through the droplet 30 and reflected on the back surface of the sample substrate 19 is simultaneously focused on the lens to cause the droplet. FIGS. 7 and 8 show a configuration for obtaining a brightness distribution of only the amount of light reflection from the surface of the droplet when the brightness distribution of the amount of light reflection from the surface of the droplet having a strong correlation with the shape cannot be obtained accurately. Will be described using.

FIG. 7 shows the simulation results when the droplet 30 is assumed to be an ideal lens. Reference numeral 43 denotes a path of light emitted from the light source 32, through which the light 39 passes through the droplet 30 and is reflected by the back surface 48 of the sample substrate 19.

It should be noted that the light 43 is specularly reflected on the back surface 48 of the sample substrate 19, and the path of the light 43 after the specular reflection is expanded downward to make the figure easier to see. In this simulation, the droplet diameter is 50 μm and the radius of curvature is 450 μm. In this case, the focal length 46 is about 1000 μm.

As shown in FIG. 7, if the thickness 47 of the sample substrate 19 is half the focal length 46, the light 43 reflected by the back surface 48 of the sample substrate 19 is focused on the point P1 of the surface 49 of the sample substrate 19. Since the focus of the lens 34 described in the imaging unit 20 is aligned with the vicinity of the upper surface of the sample substrate 19, the luminance distribution obtained by the surface reflection of the droplet 30 is added with the luminance distribution in which the vicinity of the center is locally brightened. , The brightness distribution obtained by the surface reflection of the droplet 30 cannot be accurately obtained.

When the thickness 47 of the sample substrate 19 becomes larger than half of the focal length 46, the distance between the point where the light 43 reflected by the back surface 48 of the sample substrate 19 is focused and the surface 49 of the sample substrate 19 increases. When the contrast of the light 43 reflected by the back surface 48 of the sample substrate 19 gradually decreases and the thickness 47 of the sample substrate 19 is the same as the focal length 46, the light 43 reflected by the back surface 48 of the sample substrate 19 is Obtain a uniform image in the plane.

That is, if the thickness 47 of the sample substrate 19 is made larger than the focal length 46, the light 43 reflected on the back surface of the sample substrate 19 obtains a uniform luminance distribution in the plane, so that the surface reflection of the droplet 30 Only the obtained brightness distribution can be obtained.

Similarly, when the thickness 47 of the sample substrate 19 becomes smaller than half of the focal length 46, the distance between the point where the light 43 reflected by the back surface of the sample substrate 19 is focused and the surface 49 of the sample substrate The contrast of the light 43 reflected on the back surface of the sample substrate 19 gradually decreases, but the light 43 reflected on the back surface of the sample substrate 19 is in-plane unless the thickness 47 of the sample substrate 19 approaches 0. Since it is not possible to obtain a uniform image and it becomes difficult to convey the sample substrate 19 as the thickness is reduced, the surface reflection of the droplet 30 is achieved by reducing the thickness 47 of the sample substrate 19. It is difficult to obtain only the obtained brightness distribution. Therefore, it is preferable that the thickness 47 of the sample substrate 19 is made larger than the focal length 46.

Actually, since the droplet 30 is not an ideal lens, the light 43 does not concentrate on one point, but shows a tendency similar to that of the ideal lens as shown in FIG. FIG. 8 is a model of the actual shape of the droplet 30 using a quartic function, and shows the result of simulating the path of the light transmitted through the droplet 30. As in the case of FIG. 7, the light 43 is specularly reflected on the back surface 48 of the sample substrate 19, and the path of the light 43 after the specular reflection is expanded downward to make the figure easier to see. ..

The focal length 46 in this case is defined as the distance at which when parallel light is incident from the convex side of the droplet 30, the amount of light focused within a minute range centered on the apex P2 of the droplet 30 is the largest. However, the above-mentioned minute range is the pixel size of the imaging unit derived from the sensor size of the camera in the imaging unit 20 and the magnification of the lens 34, and the thickness 47 of the sample substrate 19 is dropleted as shown by a virtual line in FIG. By making the focal length of 30 larger than the focal length 46, the light 43 reflected on the back surface of the sample substrate 19 obtains a uniform brightness distribution in the plane, so that only the brightness distribution obtained by the surface reflection of the droplet 30 can be obtained. it can.

As a result, under the above conditions, the contrast of light is lowered. In the correspondence table creation step S60 described later, it becomes easy to create a correspondence table showing the correspondence relationship between the inclination of the droplet and the brightness ratio at the position on the two-dimensional coordinate system corresponding to the position. Proportional relations or close to it, and droplets can be evaluated more accurately.

In order to make the thickness of the sample substrate 19 variable, a translucent dummy substrate may be installed between the sample substrate 19 and the measurement table 21 and stacked with a refracting liquid or the like. According to this configuration, even when the thickness of the sample substrate 19 is limited by the droplet ejection device 1, the thickness of the sample substrate 19 can be arbitrarily adjusted when taking an image with the droplet measuring device 2. Further, the thickness of the sample substrate 19 can be arbitrarily adjusted according to the shape of the droplet 30.

The polymer film 29 on the sample substrate 19 is irradiated with ultraviolet light without changing the thickness of the sample substrate 19, so that the water repellency of the sample substrate 19 is controlled and the droplet shape is made variable. May be. According to this configuration, the shape of the droplet 30 can be arbitrarily adjusted according to the thickness of the sample substrate 19.

The polymer film 29 on the sample substrate 19 is irradiated with ultraviolet light without changing the thickness of the sample substrate 19, so that the water repellency of the sample substrate 19 is controlled and the droplet shape is made variable. May be. According to this configuration, the shape of the droplet 30 can be arbitrarily adjusted according to the thickness of the sample substrate 19.

By making the amount of light 40 reflected on the front surface of the droplet 30 larger than the amount of light 43 reflected on the back surface of the sample substrate 19, the influence of the light 43 reflected on the back surface of the sample substrate 19 is relative. Can be made smaller. The same amount of light that the light 40 reflected on the front surface of the droplet 30 and the light 43 reflected on the back surface of the sample substrate 19 are determined by the difference in the refractive index between the droplet 30 and the sample substrate 19. This is because the medium in contact with the front surface of the droplet 30 and the medium in contact with the back surface of the sample substrate 19 are both air and therefore have the same refractive index. The refractive index of the droplet 30 cannot be controlled because it is determined by the ejection material, but generally, the refractive index of the resin material ejected by the inkjet method is about 1.4 to 1.6, and the refractive index of the sample substrate 19 is By making the value smaller than about 1.4 to 1.6, the influence of the light 43 reflected on the back surface of the sample substrate 19 can be made relatively small.

However, since the influence of the light 43 reflected on the back surface of the sample substrate 19 cannot be completely eliminated, it is preferable to make the thickness 47 of the sample substrate 19 larger than the focal length 46 of the droplet 30.

Since the light 43 reflected on the back surface of the sample substrate 19 also changes according to the shape of the droplet 30 like the light 40 reflected from the front surface of the droplet 30, the light 43 reflected on the back surface of the sample substrate 19. It is possible to estimate the shape from. Therefore, by depositing, for example, an aluminum film on the back surface of the sample substrate 19, the reflectance from the back surface of the sample substrate 19 is overwhelmingly higher than the reflectance from the front surface of the droplet 30. It is also possible to relatively eliminate the influence of the amount of light reflected on the front surface of the sample substrate 19 and obtain a luminance distribution of only the light 43 reflected on the back surface of the sample substrate 19. According to this configuration, when the amount of light of the light 40 reflected from the surface of the droplet 30 is not sufficient, a strong amount of light that changes according to the shape of the droplet 30 can be obtained.

The light 43 reflected on the back surface of the sample substrate 19 has a brightness that reflects the characteristics of the droplet 30 as a lens, and has an inclination of the droplet 30 as compared with the light 40 reflected from the surface of the droplet 30. Since the correlation is weak, if the amount of light is sufficient, it is preferable to obtain only the light 40 reflected from the surface of the droplet 30.

Similarly, the illumination light 39 may be configured as transmitted light that irradiates light from the back surface side of the measurement table 21 instead of vertical epi-illumination. According to this configuration, when the amount of light of the light 40 reflected from the surface of the droplet 30 is not sufficient, a strong amount of light that changes according to the shape of the droplet 30 can be obtained.

<The main part of the overall flow of the droplet measuring device>
Next, a droplet evaluation step S70 for calculating the volume or surface shape of each droplet using the image data of the droplets obtained in the imaging step S40 (see FIG. 2), a shape measurement step S50, and a corresponding table are created. Step S60 will be described with reference to FIG.

Before explaining the droplet evaluation step S70 shown in FIG. 10, the shape measurement step S50 and the correspondence table creation step S60, which prepare in advance the correspondence table necessary for executing the droplet evaluation step S70, will be described.

<Shape measurement process S50>
The shape measurement step S50 is a step of measuring the shape of a droplet at a predetermined position extracted from a plurality of droplets to be imaged (evaluation target) in the imaging step S40 with the droplet shape measuring device 4. is there. The position coordinate data (x, y, z) on the three-dimensional coordinate system (XYZ coordinate system) of the surface of the droplet is measured by the droplet shape measuring device 4.

<Corresponding table creation process S60>
In the correspondence table creation step S60, the inclination of the surface of the droplet at the position on the three-dimensional coordinate system is obtained from the position coordinate data (x, y, z) based on each profile measured in the shape measurement step S50, and the inclination thereof is obtained. A correspondence table showing the correspondence between the obtained inclination and the brightness ratio at the position on the two-dimensional coordinate system corresponding to the position (this brightness ratio is obtained from the brightness data of the droplets obtained in the imaging step S40) is provided. create. In this embodiment, the corresponding table is created by the corresponding table creation unit 26 of the measurement control unit 25. In addition, in order to parallelize the calculation time, it may be created in the corresponding table creation unit 17 of the print control unit 16.

<Droplet evaluation step S70>
Next, the droplet evaluation step S70 of FIG. 10 will be described.

The droplet evaluation step S70 is preferably performed by the volume calculation unit 27 of the measurement control unit 25, but may be performed by the volume calculation unit 18 of the print control unit 16 in order to parallelize the calculation time.

First, in step S71 of the droplet evaluation step S70, the position of each droplet is specified from the images of all the droplets ejected from all the nozzles to be evaluated, which are imaged in the imaging step S40, and each of them is specified. Create a "droplet-by-droplet image" cut out for each drop.

In step S72 of the droplet evaluation step S70, the brightness ratio is sequentially obtained from the brightness information of the image for each droplet using the "image for each droplet" obtained in step S71, and the above-mentioned correspondence table is used. , All the inclinations at the pixel positions of each pixel included in the plurality of pixels corresponding to the image of one droplet are calculated.

In step S73 of the droplet evaluation step S70, the height (provisional value) of the position of each pixel in the Z direction is determined by using all the inclination information of each pixel position obtained in step S72 for the image of one droplet. calculate.

Next, in step S74 of the droplet evaluation step S70, the outer peripheral portion of the droplet is calculated using the luminance information of the image.

Next, the height (temporary value) at the outer peripheral portion is calculated by using the outer peripheral portion of the droplet obtained in step S74 and the height (temporary value) at each pixel position obtained in step S73. The height at the outer peripheral portion is preferably obtained by averaging the heights at the pixel positions where the distance from the center of the droplet is within a certain distance from the outer peripheral portion of the droplet obtained from the outer peripheral portion of the droplet.

In step S75 of the droplet evaluation step S70, the height (temporary value) at each pixel position obtained in step S73 is set to 0 so that the height (temporary value) at the outer peripheral portion obtained as described above becomes 0. By subtracting the height (temporary value) at the outer peripheral portion from, an offset is given to the height at all pixel positions, and the height (true value) at each pixel position is calculated.

In step S76 of the droplet evaluation step S70, the pixel positions inside the outer peripheral portion of the droplet obtained in step S74 correspond to the height (true value) at each pixel position determined in step S75 and each pixel position. The volume of the one droplet is obtained by adding all the products with the pixel area for one sample droplet.

In step S77 of the droplet evaluation step S70, it is determined whether or not the calculation of the volume V of the droplets has been completed for all the droplets, and if it is determined that the calculation has not been completed, the process returns immediately before step S71 and described above. Step S72 to step S76 are repeated, and if it is determined that the process is completed, the process proceeds to step S78.

In step S78, for all the droplets of the nozzle to be evaluated obtained in step S76, the variation amount between the obtained droplet volume and the target volume of the predetermined nozzle droplet is obtained, and the droplets are obtained. The processing result of the evaluation step S70 is instructed to the print control unit 16 of the droplet ejection device 1, and the applied voltage to the piezoelectric actuator corresponding to each nozzle is adjusted so as to eject the volume of the target value.

In this way, the volume or shape of the droplet ejected by the line head 6 of the droplet ejection device 1 can be measured with high speed and accuracy by the droplet measuring apparatus 2, and the measurement accuracy can be ensured, for example. , Measurement for controlling color unevenness of a printed object and calibration of an inkjet device can be performed at high speed.

Therefore, for example, it is useful for using a droplet ejection type printing apparatus for coating and forming an organic light emitting material in the manufacture of an organic EL display panel.

(Embodiment 2)
In the first embodiment, the droplet measuring device 2 is provided separately from the droplet ejection device 1, but the droplet ejection device 1 is provided with the imaging unit 20, and the droplet measuring device 2 is measured on the production table 8. It can also be carried out by forming the recess 44 at the same position as in the case of the table 21 and processing the brightness information of the sample substrate 19 photographed by the imaging unit 20 as shown in FIG.

In the present embodiment, since the droplet ejection module head 15 is arranged in the longitudinal direction in the sub-scanning direction of the stage 9, the recess 44 is also designed to be long in the sub-scanning direction of the stage 9. There is.

In this case, the droplets can be formed by ejecting from the line head 6 in accordance with the position of the recess 44 formed in the production table 8, and the droplets are formed as in the case of the first embodiment. It is not necessary to transport the sample substrate 19 to the droplet measuring device 2, align it, and set it on the measuring table 21.

(Embodiment 3)
In the first embodiment, the print target 7 created by the droplet ejection device 1 is used as the sample substrate 19 as it is, or the print target 7 is divided into the sample substrate 19, that is, the droplets are printed. The case where the completed sample substrate 19 is set on the measurement table 21 of the droplet measuring device 2 to create a corresponding table has been described, but the line head 6 to be used in the droplet ejection device 1 is used in the droplet measuring device 2. The sample substrate 19 set on the side and on which the droplet 30 and the dummy droplet 31 are not formed is set on the measurement table 21 of the droplet measuring device 2 and used in the droplet ejection device 1 in the droplet measuring device 2. Using the planned line head 6, the droplet 30 and the dummy droplet 31 are printed on the sample substrate 19 corresponding to the position of the recess 44 of the measurement table 21, and the formed droplet 30 is imaged by the imaging unit 20. By doing so, after that, a corresponding table is created in the same manner as in the first embodiment, and this is transmitted to the print control unit 16 of the droplet ejection device 1, whereby the ejection amount of each head of the line head 6 is accurately measured. Can approach the target value.

The present invention contributes to improving the performance of a droplet ejection type printing apparatus for manufacturing a color filter of a liquid crystal display, a device such as an organic EL display, and the like.

1 Droplet ejection device 2 Droplet measuring device 3 Decompression chamber 4 Droplet shape measuring device 5 Head unit 6 Line head 7 Printable object 8 Production table 9 Stage 10 Leg 11 Support 12 Guntry 13 Support 14 Distribution tank 15 Liquid Drop ejection module head 16 Print control unit 17 Corresponding table creation unit 18 Volume calculation unit 19 Sample substrate 20 Imaging unit 21 Measurement table 22 Stage 23 Guntry 24 Stand 25 Measurement control unit 26 Corresponding table creation unit 27 Volume calculation unit 28 Support board 29 High Molecular film 30 Droplets 31 Dummy droplets 32 Light source 33 Camera 34 Lens 35 Jiggle 36 Scanning axis 37 Drive mechanism 38 Z-direction drive mechanism 39, 40, 41, 42, 43 Light 44 Recess 45 Suction path 46 Droplet focal distance 47 Thickness of sample substrate 48 Back surface of sample substrate 49 Front surface of sample substrate

Claims (6)

A translucent sample substrate on which the droplet to be measured is formed on the front surface is set on a measurement table having recesses formed on the surface so that the position on the back surface side of the droplet coincides with the recess.
The droplets formed on the sample substrate set on the measurement table are irradiated with light and imaged by an imaging unit, and the amount of reflected light from the sample substrate and the droplets is measured by the thickness of the sample substrate. Measured in a state larger than the focal length of the droplet,
A droplet measuring method for determining the volume or surface shape of the droplet based on the amount of reflected light measured by the imaging unit. A translucent sample substrate is set on a measurement table having recesses formed on the surface.
A functional material is ejected from a head having a nozzle to be evaluated toward the position of the concave portion of the measurement table to form droplets on the surface of the sample substrate.
The droplets on the sample substrate were imaged by an imaging unit, and the amount of reflected light from the sample substrate and the droplets was measured.
The droplets formed on the sample substrate set on the measurement table are irradiated with light and imaged by an imaging unit, and the amount of reflected light from the sample substrate and the droplets is measured by the thickness of the sample substrate. Measured in a state larger than the focal length of the droplet,
The nozzle of the head is evaluated by obtaining the volume or surface shape of the droplet based on the amount of reflected light measured by the imaging unit.
Droplet measurement method. The focal length of the droplet is the distance at which the light is incident from the convex side of the droplet and the light is concentrated in a minute range centered on the apex.
The method for measuring droplets according to claim 1 or 2. The minute range is a pixel size derived from the width of the camera sensor in the imaging unit and the magnification of the lens in the imaging unit.
The droplet measuring method according to claim 3. A translucent dummy substrate was placed between the sample substrate and the measurement table.
The droplet measuring method according to any one of claims 1 to 4. A water-repellent polymer film is formed on the surface of the sample substrate.
The droplet measuring method according to any one of claims 1 to 5.

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