JP2012098337A - Droplet applying device and droplet applying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve coating quality by suppressing an occurrence of inferior coating.SOLUTION: A droplet applying device 1 discharges droplets of a solution including volatile solvent, towards a coating surface of an object K to be coated to form a coating film of a prescribed pattern on the coating surface. The droplet applying device includes: a stage 2 on which the object K to be coated is placed; a coating head 5 for discharging the droplet of the solution from a discharge hole by the actuation of a driving element; a moving device 3 for moving the stage 2 and the coating head 5 relative to each other along the coating surface of the object K to be coated on the stage 2; and a control section 6 providing the driving element of the coating head 5 with a driving voltage necessary for discharging the droplet. When the stage 2 and the coating head 5 are moved relative to each other to discharge the droplet to the coating surface of the object K to be coated on the stage 2, the control section 6 increases a driving voltage for a prescribed number of discharge times from starting the discharge of the droplet by the coating head 5, more than a subsequent driving voltage after the prescribed number of discharge times and provides the driving element of the coating head 5 therewith.

Description

  The present invention relates to a droplet coating apparatus and a droplet coating method for discharging and applying a plurality of droplets to an object to be coated.

  In the case of manufacturing various display devices such as a liquid crystal display device and an organic EL (Electro Luminescence) display device or a semiconductor device, for example, when forming a color filter, or a glass substrate, a semiconductor wafer, etc. It is used when a functional thin film such as an alignment film or a resist is formed on a substrate.

  This droplet coating apparatus includes a plurality of nozzles, that is, a coating head that discharges droplets from a discharge hole toward a coating target, and each coating liquid is moved while relatively moving the coating head and the coating target. A predetermined coating film is formed in a coating region on a coating target by discharging the droplets from the ejection holes (see, for example, Patent Document 1).

  In the above-described droplet coating apparatus, a solution is used as the coating liquid. For this reason, when the solvent of the solution decreases due to volatilization or the like, the viscosity of the coating solution increases. This increase in viscosity is a factor that decreases the discharge amount of droplets. Conversely, the decrease in viscosity is a factor that increases the discharge amount of droplets. As described above, the discharge amount of the liquid droplets changes according to the viscosity of the coating liquid. In particular, in the vicinity of the opening of the discharge hole of the coating head, the solvent of the coating solution is likely to volatilize and the viscosity is likely to increase. Therefore, in order to remove the coating liquid whose viscosity has increased, dummy ejection may be performed in which droplets are continuously ejected from all ejection holes toward a receiving portion such as a tray provided separately from the object to be coated. .

JP 2005-131465 A

  However, when application is started after completion of the dummy discharge described above, the application head needs to move from the dummy discharge position, which is a position on the receiving portion, to the application start position for the application target, and this movement time is about several seconds. In the meantime, the solvent volatilization in the vicinity of the opening of the discharge hole proceeds during that time, and the viscosity of the coating liquid in the vicinity of the opening increases. In particular, the movement time of the coating head tends to become longer as the substrate becomes larger. Thus, since the viscosity of the coating liquid increases even after the dummy ejection, the ejection amount of droplets at the start of ejection is reduced, application failure such as application unevenness occurs, and the application quality is degraded.

  The present invention has been made in view of the above, and an object thereof is to provide a droplet coating apparatus and a droplet coating method capable of improving the coating quality by suppressing the occurrence of defective coating.

  A first feature according to an embodiment of the present invention is that in a droplet coating apparatus, droplets of a solution containing a volatile solvent are ejected toward a coating surface of a coating target, and a predetermined pattern is coated on the coating surface. A droplet coating apparatus for forming a film, wherein a stage on which an object to be coated is placed, a coating head that discharges droplets of a solution from a discharge hole by driving a driving element, and the stage and the coating head are placed on the stage And a control unit that applies a driving voltage necessary for ejecting droplets to the drive element. The control unit relatively moves the stage and the coating head. When a droplet is ejected onto the coating surface of the coating object on the stage, the drive voltage for a predetermined number of ejections from the start of droplet ejection by the coating head is increased from the drive voltage after the predetermined number of ejections. By giving to the drive element That.

  A second feature according to the embodiment of the present invention is that, in the droplet coating apparatus, droplets of a solution containing a volatile solvent are directed to each of the plurality of coating sections formed on the coating surface of the coating target. A droplet coating apparatus that sequentially discharges and forms a coating film of a predetermined pattern on the coating surface, and discharges droplets of a solution from a discharge hole by driving a drive element and a stage on which a coating target is placed Necessary for ejecting droplets by a predetermined number of droplet ejections for each coating section on the coating head, a moving device that moves the stage and the coating head relative to the coating surface of the coating object on the stage, and a drive element A control unit that applies a driving voltage, and the control unit relatively moves the stage and the coating head to discharge liquid droplets to a plurality of coating sections of the coating target on the stage. A predetermined number from the start of droplet discharge Is increased than the droplet ejection number of droplet discharge count for the coating compartment for coating compartment after the predetermined number, it is to provide a driving voltage to the drive element.

  According to a third aspect of the present invention, in the droplet coating method, droplets of a solution containing a volatile solvent are ejected toward the coating surface of the coating object, and a predetermined pattern is coated on the coating surface. A droplet coating method for forming a film, wherein a stage on which a coating target is placed and a coating head that discharges droplets of a solution from a discharge hole by driving a driving element are applied to the coating target on the stage. A step of applying a driving voltage necessary for ejecting droplets to the drive element, and in the step of applying, the stage and the application head are moved relative to each other to apply the application surface of the application object on the stage. When a droplet is ejected, the drive voltage for a predetermined number of ejections from the start of ejection of the droplets by the coating head is increased from the drive voltage after the predetermined number of ejections and applied to the drive element.

  According to a fourth aspect of the present invention, in the droplet coating method, a droplet of a solution containing a volatile solvent is directed to each of the plurality of coating sections formed on the coating surface of the coating target. A droplet coating method in which a coating film having a predetermined pattern is formed on a coating surface, and a droplet on which a coating target is placed and a droplet of a solution are ejected from a ejection hole by driving a driving element. A step of relatively moving the coating head along the coating surface of the coating object on the stage, and applying a driving voltage necessary for ejecting droplets by a predetermined number of droplet ejection times for each coating section to the driving element; In the giving step, when a droplet is ejected to a plurality of coating sections of an object to be coated on the stage by moving the stage and the coating head relative to each other, a predetermined number of coating sections from the start of droplet ejection by the coating head. Droplet discharge against Is increased than the droplet ejection number the number for coating compartment after a predetermined number, is to provide a driving voltage to the drive element.

  According to the present invention, it is possible to improve the quality of coating by suppressing the occurrence of defective coating.

It is a figure which shows schematic structure of the droplet coating device which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows schematic structure of the coating head with which the droplet coating apparatus shown in FIG. 1 is provided. It is a flowchart which shows the flow of the coating process which the droplet coating apparatus shown in FIG. 1 performs. It is explanatory drawing for demonstrating the measuring object pixel in the chromaticity measurement of the pixel in the application | coating process shown in FIG. It is explanatory drawing for demonstrating the relationship between the chromaticity of a pixel, and the number of pixels from the discharge start.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, in the droplet applying apparatus 1 according to the first embodiment of the present invention, the substrate K as the application target is in a horizontal state (a state along the X axis direction and the Y axis direction in FIG. 1). Stage 2, stage transport unit 3 that transports the stage 2 in the X-axis direction, driver 4 for the stage transport unit 3, and surface to be coated of the substrate K on the stage 2 (hereinafter simply referred to as “stage 2”). An application head 5 that discharges liquid droplets toward the application surface) and a control unit 6 that controls each unit are provided.

  The stage 2 is provided on the stage conveyance unit 3 and is provided so as to be movable in the X-axis direction. The placement surface of the stage 2 is formed flat, and the substrate K is placed on the placement surface by its own weight. In order to hold the substrate K on the mounting surface, a mechanism such as an electrostatic chuck or a suction chuck may be provided.

  The stage transport unit 3 supports the stage 2 and guides and moves the supported stage 2 in the X-axis direction. The stage transport unit 3 is electrically connected to the driver 4 and is driven by power supply from the driver 4. As the stage conveyance unit 3, for example, a feed screw type moving mechanism using a servo motor as a driving source, a linear motor type moving mechanism using a linear motor as a driving source, or the like is used. The stage transport unit 3 functions as a moving device that relatively moves the stage 2 and the coating head 5 along the coating surface of the substrate K on the stage 2.

  The driver 4 is electrically connected to the control unit 6, receives a control signal from the control unit 6, and supplies electric power by supplying a current to a drive source such as a motor provided in the stage transport unit 3. When the current flows to the drive source of the stage transport unit 3, the drive source is operated, and the stage 2 is moved by the stage transport unit 3 along the X-axis direction.

  The coating head 5 functions as a discharge unit that discharges a solution, which is a coating solution contained therein, to the outside as a plurality of droplets. The coating head 5 is provided on a portal column straddling the stage 2 and the stage transport unit 3 via a head transport unit (both not shown). The beam portion of the column is parallel to the Y-axis direction. The head transport unit supports the coating head 5, and guides and transports the supported coating head 5 in the Y-axis direction. As the head transport unit, for example, a feed screw type moving mechanism using a servo motor as a driving source, a linear motor type moving mechanism using a linear motor as a driving source, or the like is used.

  Here, the solution is composed of a solute that remains as a residue on the substrate K and a solvent that dissolves (disperses) the solute. For example, an ink which is a kind of solution is composed of various components such as a pigment, a solvent (ink solvent), a dispersant, and an additive. When this ink lands on the surface of the substrate K, the solvent volatilizes from the ink and solutes such as pigments remain.

  As shown in FIG. 2, the coating head 5 described above includes a nozzle plate 11 having a plurality of ejection holes 11a for ejecting liquid droplets, and a head body having a plurality of liquid chambers 12a communicating with the ejection holes 11a. 12, a flexible plate 13 that changes the volume of each liquid chamber 12 a, a plurality of piezoelectric elements 14 that deform the flexible plate 13, and a piezoelectric element drive unit 15 that drives the piezoelectric elements 14. .

  The nozzle plate 11 is formed with a plurality of ejection holes 11a arranged in a straight line at predetermined pitches (predetermined intervals) in the longitudinal direction. The arrangement direction of these discharge holes 11a is inclined by a predetermined angle with respect to the Y-axis direction (see FIG. 1), for example, and the coating head 5 is provided in the column via the head transport unit. The application head 5 is configured such that the predetermined angle can be changed. For example, the coating head 5 is supported by a rotation mechanism (not shown) so as to be rotatable in the θ direction (rotation direction along the XY plane in FIG. 1), and by the rotation mechanism, only a predetermined angle with respect to the Y-axis direction. Tilted. By changing the predetermined angle, the interval between the droplets arranged in the Y-axis direction on the substrate K, that is, the coating pitch in the Y-axis direction can be adjusted.

  In addition to each liquid chamber 12a for storing the solution, the head main body 12 communicates with the liquid chamber 12a via a branch pipe (not shown) and one end of the main pipe 12b. A liquid supply pipe 12c and a drain pipe 12d communicating with the other end of the main pipe 12b are formed. The liquid supply line 12c is a flow path for supplying a solution from the solution tank to the main line 12b, and is connected to the solution tank via a supply pipe such as a tube or a pipe. The drainage pipe 12d is a flow path for returning the solution that has passed through the main pipe 12b to the solution tank, and is connected to the solution tank via a discharge pipe such as a tube or a pipe.

  The flexible plate 13 is a plate member for increasing or decreasing the volume of each liquid chamber 12a due to the deformation. The flexible plate 13 is attached to the head body 12 so as to be able to bend and deform, and functions as a wall portion of each liquid chamber 12a. The head body 12 is formed in a rectangular frame shape, and the lower surface side opening portion is closed by the flexible plate 13. The flexible plate 13 is covered with the nozzle plate 11, and each liquid chamber 12 a is formed between the nozzle plate 11 and the flexible plate 13.

  Each piezoelectric element 14 is fixed to the flexible plate 13 so as to face each liquid chamber 12a. These piezoelectric elements 14 are electrically connected to the piezoelectric element driving unit 15 and are driven by power supply from the piezoelectric element driving unit 15. When the piezoelectric element 14 is driven to expand and contract, a part of the flexible plate 13 corresponding to the driven piezoelectric element 14 is deformed, so that the volume of the liquid chamber 12a increases or decreases according to the deformation, and the liquid chamber 12a A droplet is ejected from the communicating ejection hole 11a. This piezoelectric element 14 functions as a drive element.

  The piezoelectric element driving unit 15 is a device that is electrically connected to the control unit 6 and that can receive a control signal from the control unit 6 and apply a voltage to each piezoelectric element 14 individually. The piezoelectric element driving unit 15 individually drives each piezoelectric element 14 in accordance with a control signal from the control unit 6, and ejects droplets individually from each ejection hole 11 a of the coating head 5.

  The coating head 5 having such a configuration allows the solution in each liquid chamber 12a to be discharged from the corresponding discharge hole 11a by deformation of the flexible plate 13 in accordance with the application of the driving voltage to each piezoelectric element 14 by the piezoelectric element driving unit 15. Extrude and eject as droplets. At this time, each liquid chamber 12a is in a state filled with the solution.

  Returning to FIG. 1, the control unit 6 includes a main controller 6a for overall control and a head controller 6b for controlling the coating head 5. Connected to the main controller 6a are a chromaticity meter 6c for measuring chromaticity and a display unit 6d such as a liquid crystal display for displaying various information and images.

  The main controller 6a includes a microcomputer that centrally controls each unit, and a storage unit that stores application information related to application, various programs, and the like (none of which are shown). The application information includes a predetermined application pattern such as a dot pattern, a predetermined value V0 of the driving voltage of the application head 5, information relating to the ejection frequency (ejection timing) and the moving speed (application speed) of the substrate K. Note that it is possible to adjust the discharge amount of the droplet by changing the drive voltage, and the X-axis direction on the substrate K (the movement direction of the substrate K) by changing the discharge frequency and the movement speed of the substrate K. It is possible to adjust the interval between the droplets arranged in the line, that is, the coating pitch in the X-axis direction.

  The head controller 6b receives a control signal from the main controller 6a and controls driving of each piezoelectric element 14 by the piezoelectric element driving unit 15 provided in the coating head 5. For example, the head controller 6b receives a predetermined value V0 of the drive voltage, a discharge frequency, and the like as a control signal from the main controller 6a, and applies a predetermined drive voltage to each piezoelectric element 14 at a discharge timing based on the discharge frequency.

  The chromaticity meter 6 c measures the chromaticity of the coating film applied to the substrate K on the stage 2. For example, when application for a color filter (described later in detail) is performed on the substrate K, the chromaticity meter 6c is used for measuring the chromaticity of each pixel. Therefore, the chromaticity meter 6c is configured to be able to measure the chromaticity of the coating film applied to each pixel on the coating surface of the substrate K. For example, the chromaticity meter 6c is provided in a column via a head transport unit similarly to the coating head 5, and is configured to be movable in the Y-axis direction separately from the coating head 5 by the head transport unit. During the chromaticity measurement, the coating head 5 is retracted to a position that does not hinder the movement of the chromaticity meter 6c.

  The chromaticity meter 6c functions as a detection unit that detects the characteristics of the coating film generated by the solute of the droplets on the coating surface of the substrate K. Further, the thickness of the coating film can be obtained based on the chromaticity measured by the chromaticity meter 6c, and the coating amount of the droplets applied on the coating surface can be obtained from the thickness of the coating film. The meter 6c has a function as a detection unit that acquires information related to the discharge amount of the droplets.

  Next, a coating operation (coating method) performed by the above-described droplet coating apparatus 1 will be described. In addition, the control part 6 of the droplet coating apparatus 1 performs a coating process based on various programs. Here, a case will be described in which a color filter having pixels that are colored layers in a vertical and horizontal matrix form of the X axis and the Y axis, that is, a matrix form, is manufactured.

  As shown in FIG. 3, first, a substrate used for measurement (here, for producing a color filter used for production coating) prior to production coating, which is an operation of applying a coating solution to a substrate for color filter production. Is used as a measurement substrate.) Measurement application, which is an operation of applying a coating solution, is performed (step S1).

  However, when the application head 5 has stopped the discharge operation for a predetermined time or longer, such as when the substrate K is loaded or unloaded with respect to the stage 2, the liquid droplets are continuously discharged from all the discharge holes 11a. Dummy discharge is performed. Thereafter, when the dummy discharge is completed, the coating head 5 moves from the dummy discharge position to a coating start position at which coating on the substrate K is started. The dummy discharge position is, for example, a position where the coating head 5 faces a receiving portion (not shown) provided at the end of the stage 2 in the X-axis direction. The receiving part moves in the X-axis direction together with the stage 2 by the stage conveying part 3, and receives the droplets discharged from the respective discharge holes 11 a of the coating head 5 at the discharge position facing the coating head 5.

  In the measurement application, the control unit 6 controls the stage transport unit 3 via the driver 4 based on the application information, and controls the application head 5 by the head controller 6b while moving the stage 2 in the X-axis direction. The droplets are intermittently ejected from the respective ejection holes 11a toward the coating surface of the substrate K on the stage 2 moving in the axial direction, the dot rows are sequentially coated in the X-axis direction, and the coating surface of the measurement substrate K is coated. A scanning coating operation for forming a coating film is performed for each upper coating section.

  Here, the length of the coating head 5 in the Y-axis direction (arrangement length of the discharge holes 11a) is based on the length in the Y-axis direction of the region to be coated (the region where the coating sections are formed in a matrix) on the coating surface of the substrate K. Therefore, it is impossible to form a coating film in the coating section in the entire coating target region by one scanning coating. Therefore, the application target area is divided into a plurality of areas having dimensions that the application head 5 can cover at one time in the Y-axis direction, and the application head 5 is pitch-shifted according to the area divided in the Y-axis direction. It is assumed that scanning coating is performed. Information on the number of divisions of the application target area and the pitch movement amount of the application head 5 is stored in the storage unit of the main controller 6a as application information.

  Therefore, when the application of droplets to the application section in the area that can be covered at once by the application head 5 is completed, the application head 5 is moved by a set distance pitch in the Y-axis direction based on the application information, and the application corresponding to the next area is performed. A scan coating operation is performed to form a coating film on the compartments. Thereafter, the control unit 6 repeats the same scanning coating operation a plurality of times to form a coating film on the entire coating section on the coating surface of the substrate K. In the application for measurement, it is not necessary to apply to the entire application section on the application surface of the substrate K, and the application may be performed at least in a region corresponding to a pixel to be measured for chromaticity measurement described later.

  Here, each application section is an application region corresponding to each pixel of the color filter. That is, a black matrix as a grid-like convex portion is formed on the coated surface of the substrate for manufacturing color filters. The black matrix is a grid-like black portion that surrounds the red, green, and blue pixels of the color filter. Accordingly, each coating section is an area that has the same area as the bottom surface of each of the plurality of recesses surrounded by the black matrix and is located at the same place. In the substrate for manufacturing color filters, the bottom surface of each recess is applied. It becomes a parcel. Note that the black matrix has ink repellency, and a region other than the black matrix has ink affinity on the substrate for manufacturing color filters.

  A predetermined number of droplets, for example, eight droplets, are applied in one application section. These droplets each land in one coating section, and then flow, wet and spread, and stick to each other to form one coating film. The coating film is dried to become a colored layer. A colored layer is similarly formed in other coating sections. The total amount of several droplets is set to a predetermined amount (for example, 50 pl) so that the solute becomes substantially the same as the volume of the recess after the coating solution is dried. In addition, the common droplet discharge frequency for each application section is set in advance, and is stored as a set value in the storage unit of the main controller 6a.

  When the application for measurement is completed in step S1, the chromaticity measurement is performed by the chromaticity meter 6c (step S2). The control unit 6 controls the stage transport unit 3 via the driver 4 based on the above-described coating information, and moves the stage 2 in the X-axis direction while the chromaticity meter 6c applies the coating surface of the substrate K on the stage 2. The chromaticity of a predetermined number of colored layers present in is measured. The colored layer to be measured at this time is set in advance according to the amount of data necessary to calculate the amount of increase in drive voltage described later, and is stored as a set value in the storage unit of the main controller 6a. Yes.

  For example, as shown in FIG. 4, ten colored layers, that is, pixels located at the extreme end (left end in FIG. 4) of the substrate K and arranged in the X-axis direction are measured from the ejection start pixel. In FIG. 4, pixels for which chromaticity is to be measured are indicated by thick lines. By measuring the chromaticity of these pixels, as shown in FIG. 5, the relationship between the chromaticity of the pixel and the number of pixels from the start of ejection (first broken line A) is obtained.

  Here, the first polygonal line A is a polygonal line showing the chromaticity change of the pixel generated by the first ejection hole 11a located at the left end of the coating head 5 in FIG. 4 in all the ejection holes 11a of the coating head 5. It is. The second broken line B is a broken line indicating a change in chromaticity of the pixel generated by the second discharge hole 11a located adjacent to the first discharge hole 11a. The second broken line B indicates that the chromaticity change is substantially the same in the other ejection holes 11a other than the first ejection hole 11a.

  As shown in FIG. 5, both the first polygonal line A and the second polygonal line B require several pixels until the chromaticity of the pixel is stabilized to be substantially constant. Is lower than other pixels after chromaticity stabilization. That is, in FIG. 5, the chromaticity is stable at a substantially constant value from the third pixel onward, and the chromaticity for two pixels of the first pixel and the second pixel is lower than the third pixel onward. Yes. If the average value of the chromaticity after the third pixel in the first broken line A is a, the chromaticity of the first pixel is about 98.59% of a, and the chromaticity of the second pixel is a. It is about 99.84%. In the second broken line B, if the average value of chromaticity after the third pixel is b, the chromaticity of the first pixel is about 98.75% of b, and the color of the second pixel The degree is about 99.84% of b. Note that whether or not the chromaticity is substantially constant can be determined by whether or not the value of the chromaticity difference between the preceding and succeeding pixels is within a preset allowable value.

  The difference in chromaticity for several pixels from the start of discharge causes color unevenness, and poor application of the color unevenness causes a decrease in application quality. In the above-described application for measurement, the drive voltage applied to each piezoelectric element 14 is a predetermined value V0 stored as application information, and each of the droplets ejected at the ejection frequency set from each ejection hole 11a. Although the discharge amount should be the same, the solvent in the vicinity of the opening of the discharge hole 11a is volatilized and the solution viscosity in the vicinity of the opening increases. As shown in FIG. 5, the chromaticity of several pixels after the start of ejection becomes lower than other pixels, and several pixels are required until the chromaticity is stabilized.

  When the chromaticity measurement is completed in the above-described step S2, the pixel for increasing the drive voltage and the increase amount of the drive voltage are obtained from the result of the chromaticity measurement, and stored in the storage unit included in the main controller 6a (step S3). .

  First, the first pixel when the chromaticity for each pixel is stabilized at a substantially constant value is obtained, and the pixel before that pixel is recognized as the increase target pixel. For example, in FIG. 5, the first pixel when the chromaticity for each pixel is stabilized at a substantially constant value is recognized as the third pixel, and the first pixel and the second pixel before that are the increase target pixels. Recognized as

  Thereafter, the chromaticity difference between the chromaticity of the first pixel and the average value of the chromaticity after the third pixel is calculated, and the predetermined value V0 of the drive voltage is increased so that the chromaticity difference becomes zero. An increase amount ΔV1 is obtained. Similarly, the chromaticity difference between the chromaticity of the second pixel and the average value of the chromaticity after the third pixel is calculated, and the predetermined value V0 of the drive voltage is increased so that the chromaticity difference becomes zero. An increase amount ΔV2 to be obtained is obtained. For example, in the first pixel, the chromaticity is increased by about 1 to 2% to make the chromaticity difference zero, and in the second pixel, the chromaticity is about 0.1 to 0.2%. In order to increase the chromaticity difference to zero, an increase amount ΔV1 of the drive voltage with respect to the predetermined value V0 is obtained. That is, an increase amount of the drive voltage for compensating for a decrease in the discharge amount of the solution due to the increase in the solution viscosity near the opening of the discharge hole 11a is obtained.

  In addition, since the chromaticity change of the pixel in the 1st discharge hole 11a (1st broken line A) and the 2nd discharge hole 11a (2nd broken line B) is substantially the same, it is the color of a pixel in all the discharge holes 11a. The degree change is considered to be almost the same. Therefore, if the number of all ejection holes 11a of the coating head 5 is n, (n-1) pixels arranged in the Y-axis direction of the first pixel are also recognized as increase target pixels and correspond to these increase target pixels. The drive voltage increase amount is also obtained as being equivalent to the drive voltage increase amount ΔV1 corresponding to the first pixel. Similarly, (n−1) pixels arranged in the Y-axis direction of the second pixel are also recognized as increase target pixels, and the drive voltage increase amount corresponding to these increase target pixels is also the drive voltage corresponding to the second pixel. It is obtained as equivalent to the increase amount ΔV2. In this way, the increase target pixel and the drive voltage increase amount are obtained and stored as increase information in the storage unit included in the main controller 6a.

  Instead of storing the drive voltage increase amounts ΔV1 and ΔV2 added to the drive voltage predetermined value V0 in the storage unit, the drive voltage increase amounts V01 and V02 are obtained by adding the drive voltage increase amounts ΔV1 and ΔV2 to the drive voltage predetermined value V0. May be stored in the storage unit as drive voltages for the first and second pixels.

  In this way, including the first pixel and the second pixel, only (n−1) pixels arranged in the Y-axis direction of both of them are also recognized as increase target pixels, and the corresponding increase amount of the drive voltage is obtained. It is done. In the piezoelectric element 14 to which the driving voltage increased from the predetermined value V0 is applied, the degree of expansion / contraction increases, and thus the ejection force for ejecting the solution as droplets from the liquid chamber 12a through the ejection hole 11a increases. At this time, the discharge amount of the droplets discharged from the discharge hole 11a should normally be increased compared to the discharge amount when the predetermined value V0 of the drive voltage is applied to the piezoelectric element 14, but the discharge hole 11a Since the solution viscosity in the vicinity of the opening is increased, it becomes equal to the above-mentioned discharge amount.

  When the calculation of the increase amount of the drive voltage is completed in the above-described step S3, the production application is then performed (step S4). Since the measurement time and calculation time for the chromaticity measurement described above take several minutes, dummy discharge for continuously discharging droplets from all the discharge holes 11a is performed before the production coating, as in the case before the measurement coating. Done. When this dummy discharge is completed, the coating head 5 moves from the dummy discharge position to a coating start position at which coating is started on the substrate K.

  In the manufacturing application, similarly to the measurement application, the control unit 6 controls the stage conveying unit 3 via the driver 4 based on the application information, and moves the stage 2 in the X-axis direction, while the head controller 6b applies the application head. 5, droplets are intermittently ejected from the ejection holes 11 a toward the coating surface of the substrate K on the stage 2 that moves in the X-axis direction, and dot rows are sequentially coated in the X-axis direction. Then, a scanning coating operation for forming a coating film is performed for each coating section on the coating surface of the substrate K located in a region that can be covered at one time. When the application of droplets to the application section in the region is completed, a scanning application operation is performed in which the application head 5 is moved a set distance in the Y-axis direction based on the application information to form a coating film in the application region corresponding to the next region. Do. Thereafter, the control unit 6 repeats the same scanning coating operation a plurality of times to form a coating film on the entire coating section on the coating surface of the substrate K. In addition, when applying red ink to the substrate K, droplets are respectively applied to the application sections to which red ink is to be applied among all the application sections, and thereafter green ink and blue ink are also applied in the same manner. To do.

  However, based on the increase information including the increase target pixel and the increase amount of the drive voltage stored in the storage unit of the main controller 6a, the control unit 6 applies a predetermined number of times (for example, one pixel) from the start of discharge to the coating head 5. Is generated by eight drops, control is performed by increasing the drive voltage from the predetermined value V0 by sixteen times for two pixels. Thereby, in the ejection hole 11a corresponding to the increase target pixel, the ejection amount of the droplet is increased as compared with the case where the drive voltage is the predetermined value V0. Accordingly, each discharge amount for a predetermined number of times from the start of discharge is equivalent to the subsequent discharge amount, and as a result, each melt mass for the predetermined number of times from the start of discharge is equivalent to the subsequent melt mass. Thus, since the discharge amount of all the discharge holes 11a becomes equal and the melting mass of all the pixels becomes the same, the chromaticity of all the pixels can be made uniform.

  Thereafter, when a series of coating operations is completed, the substrate K is unloaded from the stage 2 and the next substrate K is loaded onto the stage 2. Since this carry-in / carry-in takes several minutes, the coating head 5 performs the dummy discharge again before the start of the next application, and after the dummy discharge, moves from the dummy discharge position to the application start position. Thereafter, the production coating is performed on the next substrate K. At this time as well, it is desirable to execute steps S1 to S4 in order to surely prevent the occurrence of defective coating. However, the present invention is not limited to this. For example, at the time of the second production application, the processing from step S1 to step S4 may not be executed, and the production application may be performed using the previous increase information in step S5. Therefore, it is not always necessary to execute steps S1 to S4 for each substrate K, and it may be changed depending on the type of solution and the desired coating quality.

  As described above, according to the first embodiment of the present invention, the driving voltage applied to each piezoelectric element 14 of the coating head 5 starts discharging so that the molten mass for each droplet on the substrate K is uniform. To a predetermined number of times (for example, when one pixel is generated with eight drops, it is increased 16 times for two pixels). Thereby, even when the discharge amount of the droplets is appropriately increased a predetermined number of times from the start of discharge and the solution viscosity near the opening of each discharge hole 11a is increased, each discharge amount for the predetermined number of times from the start of discharge is thereafter Equivalent to the discharge amount. Accordingly, the discharge amount of all the discharge holes 11a becomes the same, and as a result, the melting masses of all the pixels become equal, so that the chromaticity of all the pixels can be made uniform. In this way, it is possible to improve the quality of the coating film by suppressing the occurrence of poor coating of color unevenness, so that the quality of the coating film formed on the substrate K can be improved.

  In particular, since chromaticity is uniform in all pixels and color unevenness is prevented, the quality of a display panel having a color filter can be improved. Furthermore, since it is possible to apply a necessary amount of solute by a simple control of increasing the drive voltage a predetermined number of times from the start of ejection, it is possible to suppress an increase in control data and a long processing time.

  Further, the increase amount of the drive voltage is adjusted according to the chromaticity detected by the chromaticity meter 6c. This ensures that the chromaticity of each pixel for a predetermined number of times from the start of ejection is equal to the chromaticity of each pixel after the predetermined number of times, and thus it is possible to reliably suppress the occurrence of uneven application of color unevenness. .

  In the above-described manufacturing and coating, when the first scanning coating operation for coating the region that can be covered at once by the coating head 5 is completed, the coating head 5 has moved a set distance in the Y-axis direction from the completed position. Move to the start position of the second scanning application operation. Although the moving time at this time is several seconds, the coating head 5 interrupts the discharge of the droplet from the discharge hole 11a during this time. This time tends to become longer as the substrate becomes larger. For this reason, the increase information stored in the storage unit of the main controller 6a, for example, the increase amount of the drive voltage may be adjusted and used according to the ejection interruption time of the coating head 5.

  However, the discharge interruption time is a time when the application head 5 interrupts the discharge during a series of application operations, and depending on the solution, the discharge interruption time during the series of application operations may be ignored. A series of coating operations refers to an operation from the start of coating on the coating target area provided on the coating surface of one substrate K to the completion of coating on the entire coating target area. In addition, when performing multiple chamfering that creates a plurality of display panels from a single substrate K, a plurality of application target regions may be provided on the application surface of the substrate K. In this case, a series of application operations is performed until the application to all of the plurality of application target areas is completed.

  Here, for example, the discharge interruption time during a series of coating operations is negligible, that is, the increase in the solution viscosity near the opening of the discharge hole 11a due to the drying of the solvent during the discharge interruption time causes a decrease in the discharge amount. If not, the application is performed without using the aforementioned increase information corresponding to the discharge interruption time from the dummy discharge to the start of application. On the other hand, when the discharge interruption time is not negligible, that is, when the increase in the solution viscosity near the opening of the discharge hole 11a due to the drying of the solvent during the discharge interruption time is such that the discharge amount is reduced. The discharge interruption time from the dummy discharge of the application head 5 to the start of application, the discharge interruption time from the completion of the scan application operation of the application head 5 to the start of the next scan application operation (discharge interruption time between the scan application operations), The increase information stored in the storage unit of the main controller 6a, for example, the increase amount of the drive voltage is adjusted and used according to the time difference. Each discharge interruption time is known in advance from application information such as an application pattern.

  When the discharge interruption time between the scanning application operations is longer than the discharge interruption time from the dummy discharge to the start of application, the increase amount of the drive voltage is increased based on the time difference. On the other hand, when the discharge interruption time between the scanning application operations is shorter than the discharge interruption time from the dummy discharge to the start of application, the increase amount of the drive voltage is reduced based on the time difference. Note that when the ejection interruption time between the scanning application operations and the ejection interruption time from the dummy ejection of the application head to the start of application are substantially the same, the aforementioned increase information is used as it is.

  Thus, the increase amount of the drive voltage is adjusted according to the ejection interruption time of the coating head 5 during a series of coating operations on the substrate K by the coating head 5. Thereby, even when the discharge interruption time during a series of application operations is different from the discharge interruption time from the dummy discharge to the start of application, the discharge amount of all the discharge holes 11a is the same, and the dissolved mass of all the pixels becomes the same. Therefore, it is possible to reliably suppress the occurrence of poor application of color unevenness.

  When a plurality of application target areas are arranged in the scanning direction on the multi-surface substrate K, a discharge interruption time occurs between one application target area and the next application target area arranged in the scanning direction. Also in this discharge interruption time, it is possible to adjust and use the increase information stored in the storage unit of the main controller 6a based on the comparison with the discharge interruption time from the dummy discharge of the application head to the start of application.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG.

  The second embodiment of the present invention is basically the same as the first embodiment. In the second embodiment, differences from the first embodiment will be described, the same parts as those described in the first embodiment will be denoted by the same reference numerals, and the description thereof will also be omitted.

  In the droplet applying apparatus 1 according to the second embodiment of the present invention, in step S3 shown in FIG. 3, the amount of increase in the number of droplet discharges is obtained in place of the amount of increase in drive voltage. Here, in the measurement application, for example, a predetermined number of droplets of eight drops are applied to one application section. The number of droplet discharges is stored as a set value in the storage unit of the main controller 6a. The amount of increase for increasing the set value of the droplet, that is, the number of times of increase is required. In other words, the increase in the number of droplets applied to one application section (pixel) is obtained. Specifically, the number of droplets to be applied to one application section is increased by 1 or 2 from 8 droplets.

  In the production application in step S4, the control unit 6 gives a predetermined value V0 of the drive voltage to the application head 5 based on a predetermined value (for example, eight drops) of the number of droplet discharges, as in the first embodiment. Take control. However, the control unit 6 determines a predetermined application section from the start of discharge of the application head 5 in all lines based on the increase information including the increase target pixel and the amount of increase in the number of droplet discharges stored in the storage unit of the main controller 6a. The number of droplet discharges is increased by a certain number (for example, two pixels). In order to increase the number of droplets applied to the application section, the application interval of the droplets in the application section may be narrowed. It is possible to increase the coating speed, to increase the coating speed (moving speed of the substrate K), or to combine them.

  Thereby, in a predetermined application section (for example, all the pixels including the first pixel and the second pixel and arranged in the Y-axis direction respectively) from the start of discharge, the number of droplets that land on the other application section Compared to increase. Therefore, each discharge amount for a predetermined application section from the start of discharge is different from the subsequent discharge amount, but the dissolved mass contained in the coating liquid applied in the predetermined application section from the start of discharge is equivalent to the subsequent dissolved mass It becomes. As a result, the melting masses of all the coating sections, that is, all the pixels are equal, so that the chromaticity of all the pixels can be made uniform. In this way, it is possible to improve the coating quality by suppressing the occurrence of uneven application of color unevenness.

  As described above, according to the second embodiment of the present invention, instead of increasing the drive voltage of the increase target pixel, the first embodiment can also be performed by increasing the number of droplet discharges of the increase target pixel. The same effect as the form can be obtained. In addition, since it is possible to apply a required amount of solute by a simple control of increasing the number of droplet discharges for a predetermined coating section from the start of discharge, the increase in control data and the length of processing time are suppressed. be able to.

(Other embodiments)
In addition, the above-mentioned embodiment which concerns on this invention is an illustration, and the scope of the invention is not limited to them. The above-described embodiment can be variously modified. For example, some components may be deleted from all the components shown in the above-described embodiment, and further, components according to different embodiments may be appropriately combined. Also good.

  In the above-described embodiment, a color filter is manufactured by forming a colored layer as a coating film on the substrate K. However, the present invention is not limited to this, and an alignment film is formed as a coating film on the substrate K. Alternatively, a resist film may be formed as a coating film. In these cases, instead of using the chromaticity meter 6c that measures the chromaticity of the colored layer that is a pixel, for example, a film thickness meter that measures the thickness of the alignment film or the thickness of the resist film, or each dropped film A drop amount detector or the like for detecting the drop amount from the landing diameter or landing area of the droplet may be used. The film thickness meter functions as a detection unit that detects the thickness of the coating film generated by the solute of the droplets on the substrate K. In addition, since the coating amount of the droplet applied on the coating surface can be obtained from the thickness of the coating film detected by the film thickness meter, the film thickness meter serves as a detection unit that acquires information on the droplet ejection amount. It has a function.

  In the case where an alignment film material is applied to form an alignment film on a rectangular application target region set on one or a plurality of substrates on the substrate K, first, a measurement in which a liquid repellent treatment is applied to the surface. The measurement application for applying droplets is performed on the production substrate based on the application information for the production substrate stored in the storage unit. The liquid droplets applied on the substrate K that has been subjected to the liquid repellent treatment have a hemispherical shape independently of each other without spreading due to the liquid repellency of the substrate K.

  After the application for measurement, the amount of each droplet applied on the substrate is detected using the above-described droplet amount detector. That is, a camera that images a droplet from directly above is moved relative to the substrate K in the surface direction under the control of the control unit 6, sequentially positioned at a predetermined imaging target position, and dropped at each position. The taken droplet is imaged from directly above. The captured image is subjected to image processing using an image processing device (not shown), and the amount of the droplet is calculated as the droplet discharge amount from the area or diameter of the droplet image in the captured image. For example, as in the first embodiment, the imaging target position is about 20 to 40 droplets from the ejection start position among the droplets applied by the first ejection hole 11a located at the left end of the coating head 5. Yes, this number is sufficient to stabilize the discharge amount almost constant and can be determined by empirical values or experiments.

  A line graph representing the relationship between the drop position and the discharge amount is created from the calculated discharge amount of each droplet. In this graph, similarly to FIG. 5, the discharge amount is stabilized at a substantially constant value after the nth drop from the start of discharge. Here, it is assumed that the discharge amount tends to be almost stable after the 15th drop.

  Based on this result, the increase amount of the drive voltage related to the discharge of 14 drops until the discharge amount is stabilized is obtained. That is, for each of the 14 droplets, the difference from the stabilized discharge amount is obtained, and the increase amount of the drive voltage is calculated to offset the difference. The increase amount of the drive voltage according to the difference in the discharge amount can be determined by obtaining a relationship between the drive voltage and the discharge amount in advance by experiment and referring to the relationship. The amount of increase in drive voltage for 14 drops is stored in the storage unit as drive voltage increase information.

  Further, since the relationship between the dropping position and the discharge amount is considered to show the same tendency in the other ejection holes 11a other than the first ejection hole 11a in the coating head 5, the driving voltage at each dropping position determined above is used. The increase amount is similarly applied to the other discharge holes 11a.

  When manufacturing and coating is performed on a production substrate, the ejection of droplets from the ejection holes 11a of the coating head 5 is controlled based on the coating information set as described above.

  In addition, the detection unit that detects the characteristics of the coating film generated by the solute of the droplets on the substrate K detects the amount of transmitted light and the absorbance of the coating film even if it measures the electrical resistance of the coating film. It may be what you do.

  In the above-described embodiment, when a discharge interruption time occurs during a series of application operations on the application surface of the substrate K, the discharge interruption time is stored in the storage unit of the main controller 6a according to the length of the discharge interruption time. However, in the measurement application, the increase amount of the drive voltage required as a result of the decrease in the discharge amount due to the discharge interruption described above may be obtained in advance. good.

  Further, since the amount of decrease in the discharge amount accompanying the increase in the viscosity of the solution shows the same tendency in each discharge hole 11a, the drive obtained based on the information on the discharge amount obtained in one or two discharge holes 11a. Although it has been described that the increase amount of the voltage is applied to all the discharge holes 11a, information on the discharge amount is individually detected for each discharge hole 11a, and the increase amount of the drive voltage is set. Also good.

  In the above-described embodiment, the substrate K is moved in the X-axis direction with respect to the coating head 5. However, the present invention is not limited to this, and the coating head 5 is moved in the X-axis direction with respect to the substrate K. In short, the application head 5 and the substrate K may be moved relative to each other.

DESCRIPTION OF SYMBOLS 1 Droplet coating device 2 Stage 3 Stage conveyance part (moving device)
5 coating head 6 control unit 6c chromaticity meter (detection unit)
14 Piezoelectric elements (drive elements)

Claims (8)

A droplet coating apparatus that discharges droplets of a solution containing a volatile solvent toward a coating surface of an object to be coated, and forms a coating film having a predetermined pattern on the coating surface,
A stage on which the application object is placed;
A coating head for discharging droplets of the solution from the discharge holes by driving of a driving element;
A moving device that relatively moves the stage and the application head along the application surface of the application object on the stage;
A controller that applies a driving voltage necessary for discharging the droplets to the driving element;
With
The control unit, when relatively moving the stage and the coating head and discharging the droplet onto the coating surface of the coating object on the stage, starts from a droplet discharge start by the coating head. The droplet coating apparatus, wherein the drive voltage for the number of ejections is applied to the drive element by increasing the drive voltage after the predetermined number of ejections. Droplets for sequentially discharging droplets of a solution containing a volatile solvent toward each of a plurality of coating sections formed on the coating surface of a coating object, and forming a coating film having a predetermined pattern on the coating surface A coating device,
A stage on which the application object is placed;
A coating head for discharging droplets of the solution from the discharge holes by driving of a driving element;
A moving device that relatively moves the stage and the application head along the application surface of the application object on the stage;
A controller that applies a driving voltage necessary for discharging the droplets to the driving element by a predetermined number of droplet discharging times for each coating section;
With
When the controller is configured to relatively move the stage and the coating head to discharge the droplets to the plurality of coating sections of the coating target on the stage, the droplets are ejected by the coating head. The droplet is characterized in that the number of droplets discharged to a predetermined number of coating sections from the start is increased more than the number of droplets discharged to the coating sections after the predetermined number, and the driving voltage is applied to the driving element. Coating device. It further comprises a detection unit that acquires information related to the ejection amount of the droplets ejected onto the application object,
3. The droplet applying apparatus according to claim 1, wherein the control unit adjusts the increase amount based on information on a discharge amount of the droplet acquired by the detection unit.   When the controller starts the discharge again after stopping the discharge of the droplet by the application head during a series of application operations to the application target by the application head, the discharge of the application head before the start of the discharge is interrupted. 4. The droplet coating apparatus according to claim 1, wherein the amount of increase in the first discharge start for the coating object is adjusted and used according to time. A droplet coating method in which droplets of a solution containing a volatile solvent are discharged toward a coating surface of an object to be coated, and a coating film having a predetermined pattern is formed on the coating surface,
Relatively moving the stage on which the coating object is placed and the coating head that discharges the droplets of the solution from the discharge holes by driving the drive element along the coating surface of the coating object on the stage, Providing the driving element with a driving voltage necessary for discharging the droplet;
In the applying step, when the droplet is ejected onto the coating surface of the coating object on the stage by relatively moving the stage and the coating head, a predetermined period from the start of droplet ejection by the coating head A droplet coating method, wherein the drive voltage for the number of ejections is applied to the drive element by increasing the drive voltage after the predetermined number of ejections. Droplets for sequentially discharging droplets of a solution containing a volatile solvent toward each of a plurality of coating sections formed on the coating surface of a coating object, and forming a coating film having a predetermined pattern on the coating surface Application method comprising:
Relatively moving the stage on which the coating object is placed and the coating head that discharges the droplets of the solution from the discharge holes by driving the drive element along the coating surface of the coating object on the stage, Providing the driving element with a driving voltage necessary for ejecting the droplets by a predetermined number of droplet ejection times for each coating section;
In the applying step, when the droplet is ejected to the plurality of coating sections of the coating object on the stage by relatively moving the stage and the coating head, the droplet is ejected by the coating head. The droplet is characterized in that the number of droplets discharged to a predetermined number of coating sections from the start is increased more than the number of droplets discharged to the coating sections after the predetermined number, and the driving voltage is applied to the driving element. Application method. Further comprising obtaining information on the ejection amount of the droplets ejected onto the application object;
The droplet application method according to claim 5 or 6, wherein, in the giving step, the increase amount is adjusted based on information on the ejection amount of the droplet obtained in the obtaining step.   In the applying step, during a series of coating operations performed on the coating object by the coating head, when the ejection of droplets by the coating head is interrupted and then the ejection is started again, the ejection of the coating head is suspended before the ejection is started. 8. The droplet coating method according to claim 5, wherein the increase amount at the start of the first discharge for the coating object is adjusted and used according to time.

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