JP6245726B2 - Ink jet apparatus and droplet measuring method - Google Patents

Description

  The present invention relates to an inkjet apparatus and a droplet measurement method capable of measuring the volume of individual droplets ejected from a plurality of nozzles of an ink head with high accuracy.

  The ink jet method is used in a process of manufacturing an organic EL display, for example, because ink can be accurately dropped onto a predetermined position on a substrate. For example, Patent Document 1 below describes a method of forming each organic light emitting material layer of R (red), G (green), and B (blue) by an inkjet method. In addition, there is known a mechanism equipped with a mechanism for determining the quality of an ink ejection port based on the form of droplets ejected from an ink head. For example, Patent Document 2 described below describes a method of photographing a droplet ejected from an ink head on its flight path and determining the quality of an ejection port based on a photographed image of the droplet.

JP 2003-77678 A JP 2011-2641 A

  In recent years, organic EL displays have been produced by a method in which R, G, and B organic light-emitting material layers are separately applied by vapor deposition, but it is necessary to use a mask and is not suitable for large displays and large substrates. Therefore, as described above, the production of a light emitting layer by an ink jet printing method is attracting attention. However, since the variation in the amount of ejected ink has a large effect on the image quality of the display, the film thickness of the light emitting layer is extremely high. Therefore, it is necessary to precisely control the amount of liquid droplets discharged onto the substrate.

  In view of the circumstances as described above, an object of the present invention is to provide an ink jet apparatus and a droplet measuring method capable of measuring the amount of ink droplets with high accuracy.

In order to achieve the above object, an ink jet apparatus according to an aspect of the present invention includes one or more head units, a stage, a light source, a light receiving unit, and a controller.
The head unit is configured to be able to eject ink droplets.
The stage is configured to support a substrate to which the droplets are applied and to be relatively movable with respect to the head unit.
The light source is configured to be able to irradiate illumination light to the droplet on the substrate.
The light receiving unit is configured to receive reflected light of the illumination light from the droplet.
The controller is configured to be able to acquire information on the amount of the droplet based on the intensity of the reflected light received by the light receiving unit.

In order to achieve the above object, a droplet measuring method according to an aspect of the present invention includes a step of ejecting ink droplets from at least one head unit toward a substrate on a stage.
Illumination light is irradiated from a light source toward the droplets before drying applied to the substrate.
The reflected light of the illumination light from the droplet is received by the light receiving unit.
Information on the amount of the droplet is acquired based on the intensity of the received reflected light.

1 is a schematic plan view showing an ink jet apparatus according to an embodiment of the present invention. It is a schematic side view which shows the said inkjet apparatus. It is an enlarged view of the principal part which shows the ink discharge surface of the ink head in the said inkjet apparatus. It is a schematic plan view explaining the effect | action of the said inkjet apparatus. It is a schematic block diagram of the liquid quantity measurement unit in the said inkjet apparatus. It is a figure explaining the effect | action of the said liquid quantity measurement unit. It is a front view explaining the positional relationship of the light source and light-receiving part which comprise the said liquid quantity measurement unit. It is sectional drawing which shows typically the mode of the droplet after drying. In an embodiment of the present invention, it is a figure showing an example of an output of a controller about brightness of reflected light of a droplet acquired by a light sensing part. It is a principal part top view of the board | substrate explaining the adjustment process of the light-receiving part of the said liquid quantity measurement unit.

An ink jet apparatus according to an embodiment of the present invention includes one or more head units, a stage, a light source, a light receiving unit, and a controller.
The head unit is configured to be able to eject ink droplets.
The stage is configured to support a substrate to which the droplets are applied and to be relatively movable with respect to the head unit.
The light source is configured to be able to irradiate illumination light to the droplet on the substrate.
The light receiving unit is configured to receive reflected light of the illumination light from the droplet.
The controller is configured to be able to acquire information on the amount of the droplet based on the intensity of the reflected light received by the light receiving unit.

  The intensity of the reflected light from the droplet applied onto the substrate changes according to the surface shape of the droplet, and the surface shape of the droplet is substantially determined by the amount (volume) of the droplet. The surface shape of the droplet is affected by, for example, the surface tension of the organic solvent carrying the ink pigment or dye, and a difference in the amount of the droplet tends to appear as a difference in the surface shape of the droplet before the droplet is dried. The controller acquires information on the amount of the droplet based on the correlation between the surface shape of the droplet and the received light intensity of the reflected light.

  According to the above-described ink jet apparatus, highly accurate droplet measurement with little variation is possible. Compared with the method that measures the droplet volume (volume) by photographing the droplets ejected from the head part on the flight path and image-processing it, the calculation load on the controller can be reduced, so it takes a short time. Droplet measurement can be performed at Furthermore, since it is possible to measure droplets in a short time, it is possible to optimize the discharge amount by quickly feeding back, for example, a discharge failure to the head portion, and target all droplets on the substrate. Inspection for the presence or absence of uneven coating can be performed.

Typically, the head unit has a plurality of nozzles that can eject the droplets. In this case, the ink jet apparatus may further include a drive unit configured to be able to move the light receiving unit relative to the stage.
As a result, the measurement conditions such as the light receiving direction of the reflected light with respect to the individual droplets can be made common, and a decrease in measurement accuracy due to the difference in the measurement conditions can be prevented. In addition, it is possible to measure the received light intensity with a plurality of droplets as one unit, and the processing time can be shortened.

The controller controls the movement of the light receiving unit by the driving unit, and the plurality of liquids based on the intensity of the reflected light from the plurality of droplets ejected from the plurality of nozzles and applied onto the substrate. You may acquire the information regarding the amount of drops, respectively.
As a result, it is possible to compare the amounts of individual droplets, and it is possible to easily detect abnormal ejection or the like.

  The light receiving unit may include a camera capable of simultaneously imaging the plurality of droplets applied on the substrate. The camera includes a linear sensor or an area sensor. With the above configuration, reflected light from a plurality of droplets can be received simultaneously, so that the measurement time can be shortened.

  The light receiving unit may be disposed at an asymmetric position with respect to the light source with respect to an axis orthogonal to the surface of the substrate. As a result, it is possible to suppress the regular reflection light of the illumination light on the substrate surface from being received by the light receiving unit, and thus it is possible to accurately detect the reflected light from the droplet.

Typically, the stage is configured to be movable relative to the head unit along the first axial direction. In this case, the controller may be configured to be able to control the driving unit so as to move the light receiving unit along a second axial direction intersecting the first axial direction.
As a result, it is possible to perform application of droplets on the substrate and measurement of the discharge amount of the droplets on the same stage.

  The head part may include a plurality of head parts arranged along a uniaxial direction. Thereby, it can be easily applied to a large substrate.

  The controller may be configured to generate a control signal for controlling the ejection amount of the droplet based on information related to the amount of the droplet, and to output the control signal to the head unit. Thus, when an ink ejection abnormality occurs, it can be quickly fed back to the head unit. In addition, since it is not affected by the crosstalk between the nozzles, it is possible to accurately measure droplets and to quickly feed back the ejection abnormality of the head portion.

A droplet measurement method according to an embodiment of the present invention includes a step of ejecting ink droplets from at least one head unit toward a substrate on a stage.
Illumination light is irradiated from a light source toward the droplets before drying applied to the substrate.
The reflected light of the illumination light from the droplet is received by the light receiving unit.
Information on the amount of the droplet is acquired based on the intensity of the received reflected light.

  According to the droplet measuring method, highly accurate droplet measurement with little variation is possible. Compared with the method that measures the droplet volume (volume) by shooting the droplets ejected from the head part on the flight path and image-processing it, the computation load can be reduced in a short time. Droplet measurement is possible. Furthermore, since it is possible to measure droplets in a short time, it is possible to optimize the discharge amount by quickly feeding back, for example, a discharge failure to the head portion, and target all droplets on the substrate. Inspection for the presence or absence of uneven coating can be performed.

Typically, in the step of discharging the droplets, a plurality of droplets are discharged from a plurality of nozzles of the head unit. In this case, in the step of receiving the reflected light, the reflected light from the plurality of droplets coated on the substrate may be received while the light receiving unit is moved relative to the stage.
As a result, the measurement conditions such as the light receiving direction of the reflected light with respect to the individual droplets can be made common, and a decrease in measurement accuracy due to the difference in the measurement conditions can be prevented. In addition, it is possible to measure the received light intensity with a plurality of droplets as one unit, and the processing time can be shortened.

  In the step of acquiring the information, information on the amount of the plurality of droplets may be acquired based on the intensity of reflected light from the plurality of droplets applied on the substrate. As a result, it is possible to compare the amounts of individual droplets, and it is possible to easily detect abnormal ejection or the like.

Typically, in the step of ejecting the droplet, the droplet is ejected while moving the stage in the first axial direction with respect to the head portion. In this case, the step of receiving the reflected light may receive the reflected light while moving the light receiving unit along the second axis direction intersecting the first axis direction with respect to the stage. .
As a result, it is possible to perform application of droplets on the substrate and measurement of the discharge amount of the droplets on the same stage.

  The droplet measurement method may further generate a control signal for controlling the ejection amount of the droplet based on information on the amount of the droplet, and output the control signal to the head unit. This makes it possible to promptly feed back to the head section when an ink ejection abnormality occurs. In addition, since it is not affected by the crosstalk between the nozzles, it is possible to accurately measure droplets and to quickly feed back the ejection abnormality of the head portion.

  The droplet measuring method may further control the ejection amount of the droplet using reflected light of the illumination light from a test droplet applied on the substrate. This makes it possible to measure and control the ink amount with higher accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[overall structure]
FIG. 1 is a schematic plan view showing an inkjet apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic side view thereof. In each drawing, the X axis and the Y axis indicate horizontal directions orthogonal to each other, and the Z axis indicates a vertical direction orthogonal to the X axis and Y axis, respectively.

  The inkjet apparatus 1 of the present embodiment includes a stage 11 that supports a substrate S, a head module 12 that applies ink droplets to the substrate S on the stage 11, a moving mechanism 13 that moves the stage 11 in a uniaxial direction, And a controller 15 that controls the overall drive of the ink jet apparatus 1 including the head module 12, the moving mechanism 13, and the like.

  The ink jet device 1 according to the present embodiment is used, for example, for printing a colored layer of a color filter or a light emitting layer for an organic EL panel.

  The substrate S is composed of a substantially rectangular glass substrate, but may be composed of a plate, sheet, or film substrate such as metal, plastic, or paper. The substrate S is not limited to a single layer, and may have a multilayer structure in which a solid film such as an insulating film or a conductive film or a functional film patterned in a predetermined shape is laminated on the surface.

  The stage 11 is installed on the base portion 10 so as to be movable in the Y-axis direction. The stage 11 has a support surface 11a supported by the substrate S. The support surface 11a belongs to planes (XY plane) parallel to the X-axis direction and the Y-axis direction, respectively, and is configured by a substantially rectangular flat surface in the present embodiment. The stage 11 may include various chuck mechanisms for holding the substrate S on the support surface 11a.

  The ink jet apparatus 1 may include a cooling mechanism 14 for cooling the support surface 11a of the stage 11 to a predetermined temperature or less. The said predetermined temperature is not specifically limited, For example, it sets to the appropriate temperature which can delay the drying of the droplet apply | coated on the board | substrate S. The cooling mechanism 14 includes, for example, a cooling water circulation passage formed inside the stage 11 and a pump unit that circulates the cooling water through the circulation passage. The pump unit may be integrally attached to the stage 11 or may be installed on the base portion 10 or other part via a flexible pipe member through which cooling water passes.

  The moving mechanism 13 controls a pair of guide rails 13a and 13b laid on the base portion 10, a driving source such as a linear motor that moves the stage 11 along the guide rails 13a and 13b, and the driving source. Includes a control unit and the like. The pair of guide rails 13a and 13b extend parallel to the Y-axis direction, and the stage 11 is installed on the guide rails 13a and 13b. The drive source is arranged inside the stage 11, and the control unit performs highly accurate movement control of the stage 11 along the guide rail.

[Head module]
The head module 12 has a plurality of head portions 121, 122, 123, 124, 125, 126. The head portions 121 to 126 are configured to apply a predetermined ink droplet D to the entire surface of the substrate S on the stage 11 moving in the Y-axis direction along the guide rails 13a and 13b. The head module 12 may be composed of a single head part.

  When the head portions 121 to 126 virtually divide the entire surface of the substrate S on the stage 11 by a plurality of regions R1, R2, R3, R4, R5, and R6 arranged along the X-axis direction, Arranged so as to correspond to each of the plurality of regions R1 to R6. The regions R1 to R6 defined on the surface of the substrate S are each formed in a rectangular shape having a longitudinal direction parallel to the Y-axis direction and a width direction parallel to the X-axis direction. An ink droplet D is applied to R6 at a predetermined pitch in the X-axis direction and the Y-axis direction, respectively.

  The plurality of regions R1 to R6 are divided into a first region group RA and a second region group RB. In the present embodiment, the first region group RA is composed of a plurality of regions R1, R3, and R5 selected every other column from the plurality of regions R1 to R6, and the second region group RB is composed of a plurality of columns. Among the regions R1 to R6, a plurality of remaining regions R2, R3, and R5 are formed.

  The first area group RA is processed by the head parts 121, 123 and 125. That is, the head parts 121, 123, 125 apply the droplets D to the regions R1, R3, R5 constituting the first region group RA, respectively. On the other hand, the second region group RB is processed by the head portions 122, 124 and 126. That is, the head portions 122, 124, 126 apply the droplets D to the regions R2, R4, R6 constituting the second region group RB, respectively.

  The head portions 121, 123, and 125 constitute a first head group 12A. The first head group 12A is installed at a position directly above the base portion 10 via the support frame 120A, and the head portions 121, 123, and 125 are first region groups RA (R1, R3, R5) on the substrate S, respectively. Are positioned so as to face each other. On the other hand, the head portions 122, 124, and 126 constitute the second head group 12B. The second head group 12B is installed at a position directly above the base portion 10 via the support frame 120B, and the head portions 122, 124, 126 are respectively second region groups RB (R2, R4, R6) on the substrate S. Are positioned so as to face each other.

  The head module 12 includes a plurality of rotation mechanism units M (adjustment mechanisms) that can rotate the head units 121 to 126 about the Z axis. These rotation mechanism portions M are provided on the support frames 120A and 120B, respectively, and are configured to be able to individually rotate the head portions 121 to 126 over a predetermined angle range around the Z axis. These rotation mechanisms M are controlled by the controller 15.

  The controller 15 is typically composed of a computer including a CPU and various memories. The controller 15 controls driving of various mechanisms such as the head module 12, the moving mechanism 13, the cooling mechanism 14, and a liquid amount measuring unit 16 described later. The controller 15 is installed in the base unit 10, but may be installed in a position different from the base unit 10.

  Each of the head parts 121 to 126 has an ink ejection surface on which a plurality of nozzles are formed. FIG. 3 is an enlarged view of a main part showing the ink discharge surface 121 s of the head part 121. The ink ejection surface 121s has a substantially rectangular shape, and a plurality of nozzles N are formed at a predetermined pitch p0 along the longitudinal direction. Each nozzle N is connected to an ink tank (not shown), and each nozzle N is provided with a piezoelectric driving unit V for ejecting a predetermined amount of ink. The piezoelectric drive unit V is controlled by the controller 15. The ink discharge surface 121s is disposed so as to face the surface of the substrate S that passes immediately below the ink discharge surface through a predetermined distance.

  The rotation mechanism unit M adjusts the droplet discharge pitch along the X-axis direction by rotating the head unit 121 around the Z-axis. For example, FIG. 3A shows a state in which the droplet discharge pitch along the X-axis direction is converted from p0 to p1 when the head unit 121 is tilted by an angle θ1 around the Z-axis with respect to the X-axis. In FIG. 3B, the droplet discharge pitch along the X-axis direction when the head portion 121 is tilted by an angle θ2 (θ2> θ1) around the Z-axis with respect to the X-axis is from p0 to p2 (p2 It shows how it is converted into <p1). In this manner, the droplet discharge pitch along the X-axis direction can be continuously changed according to the rotation angle of the head unit 121.

  The head units 122 to 126 are configured in the same manner as the head unit 121. The droplet discharge pitches along the X-axis direction of the head units 121 to 126 are set to be the same. The droplet discharge pitch along the X-axis direction is appropriately adjusted according to the type and process of the droplet applied onto the substrate S.

  The head parts 121, 123, and 125 constituting the first head group 12A are arranged on the same straight line along the longitudinal direction thereof. Similarly, the head portions 122, 124, and 126 that constitute the second head group 12B are arranged on the same straight line along the longitudinal direction thereof. Instead of this, the respective head portions constituting the first and second head groups 12A and 12B may be arranged along the X-axis direction.

  The second head group 12B is arranged at a position offset (separated) from the first head group 12A in the movement direction (Y-axis direction) of the substrate S. As described above, the head portions 121 to 126 are arranged corresponding to all the regions R1 to R6 on the substrate S, so that the ink can be applied to the entire surface of the substrate S by one movement operation of the substrate S in the Y-axis direction. It is possible to apply the droplets. Thereby, the efficiency of the droplet application process for the substrate S is increased, and the productivity can be improved.

  FIG. 4 is a schematic plan view showing a state in which droplets are applied to the surface of the substrate S by the head module 12. The substrate S moves at a predetermined speed in the direction indicated by the arrow A along the Y-axis direction directly below the head module 12. On the surface of the substrate S, droplets D ejected from the head module 12 are applied from the start end S1 toward the end S2.

  The droplets D are applied at constant pitches px and py in the X-axis direction and the Y-axis direction. The pitch px is adjusted by the rotation angle of the head units 121 to 126 by the rotation mechanism unit M, and the pitch py is adjusted by the discharge timing of the droplets D from the head units 121 to 126. The droplet layer formed on the substrate S may be formed by discharging the droplet D once, or may be formed by discharging the droplet D a plurality of times. Further, the droplet layer formed on the substrate S may be a pixel surrounded by ribs formed for a liquid repellent material, or a lyophilic / liquid repellent region is directly formed on the substrate S. May be.

  In the present embodiment, as described above, the head module 12 is configured by the first head group 12A and the second head group 12B, and the first head group 12A is located upstream of the second head group 12B. Be placed. Therefore, as shown in FIG. 4, first, droplets D are discharged onto the substrate S to the first region group RA (R1, R3, R5) by the first head group 12A (head portions 121, 123, 125). Thereafter, the second head group 12B (head portions 122, 124, 126) starts discharging the droplets D to the second region group RB (R2, R4, R6).

[Liquid measurement]
The ink discharge amount in ink jet printing is adjusted by measuring the ink discharge amount directly or indirectly and feeding it back so that it becomes an optimum value. As a method for measuring the discharge amount, a method for measuring the volume and speed of a flying droplet, a method for measuring a film thickness of a coating film after drying applied on a substrate, and the like are known. However, the method of measuring flying droplets requires precise measurement for each nozzle, and therefore requires time for feedback, and is easily affected by crosstalk between nozzles. On the other hand, the method of measuring the film thickness of the coated film after drying has problems such as failure to promptly feed back when a discharge abnormality occurs. In any case, since it takes time to measure, it is necessary to reduce the number of measurement points. Furthermore, measurement variation is large and accurate measurement is difficult.

  Therefore, in the present embodiment, it is possible to measure the discharge amount of the droplet D in the liquid state before the droplet D is dried for the droplet D on the substrate S immediately after being discharged from the head parts 121 to 126. It is configured. The droplet D may be formed by one drop of ink, or may be formed by an aggregate of a plurality of drops of ink. FIG. 5 is a schematic configuration diagram of the liquid amount measurement unit 16.

  The liquid amount measurement unit 16 includes a light source 161 and a light receiving unit 162. The light source 161 irradiates the droplet D on the substrate S applied by the head module 12 with the illumination light L1. The light receiving unit 162 receives the reflected light L2 of the illumination light L1 from the droplet D and outputs the received light signal to the controller 15.

  The light source 161 may be a linear light source such as a fluorescent tube, or a point or planar light source such as an LED (Light Emitting Diode). The wavelength band of the illumination light L1 is not particularly limited. For example, visible light is used, and light having a wavelength that has high reflection characteristics with respect to the droplet D and high light receiving sensitivity of the light receiving unit 162 is used. The light source 161 is installed above the substrate S, for example. Further, as the light source (illumination light), it is preferable to select light having a wavelength that can prevent adverse effects on the applied ink. For example, the use of light in a wavelength band that can cause adverse effects such as changes in the physical properties of the ink, such as ultraviolet rays and infrared rays in the heat ray region, should be avoided. It should be noted that ultraviolet rays and infrared rays are not intended to be always excluded as light source light, and can be applied to inks with little or no adverse effects.

  The light receiving unit 162 includes a solid-state imaging device (electronic camera) such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor). Such a light receiving unit 162 includes, for example, a linear sensor and an area sensor. By configuring the light receiving unit 162 with an area sensor such as a CCD camera, it is possible to optically measure a macro area on the substrate S, and information about a plurality of droplets can be acquired.

  The liquid amount measurement unit 16 is installed, for example, above the substrate S, and is supported by a pedestal 160 installed in the base unit 10 as shown in FIG. The gantry 160 is provided so as to straddle the guide rails 13a and 13b on the downstream side of the head module 12 in the transport direction of the substrate S.

  The ink jet apparatus 1 further includes a drive unit 17 (see FIG. 2), and the drive unit 17 is configured to be able to move the liquid amount measurement unit 16 along the gantry 160 in the X-axis direction. As a result, the light source 161 and the light receiving unit 162 can move relative to the substrate S on the stage 11 moving in the Y axis direction in the X axis direction, and the light receiving unit 162 can move from the droplets D over the entire surface of the substrate S. It becomes possible to receive the reflected light L2. The movement of the liquid amount measurement unit 16 by the drive unit 17 is controlled by the controller 15.

  The light source 161 is not limited to being configured integrally with the light receiving unit 162, and may be configured separately from the light receiving unit 162. For example, the light source 161 is installed on the pedestal 160, for example. In this case, in order to uniformly irradiate each region on the substrate S with the illumination light L1, the light source 161 may be configured by a linear light source extending in the X-axis direction or linearly in the X-axis direction. You may be comprised by the some point light source arranged.

  The controller 15 acquires information related to the amount of the droplet D based on the intensity of the reflected light L2 received by the light receiving unit 162.

  That is, the intensity of the reflected light L2 from the droplet D applied on the substrate S changes according to the surface shape of the droplet, and the surface shape of the droplet depends on the amount (volume) of the droplet and the substrate S. It is almost determined by the height from. The surface shape of the droplet D is affected by, for example, the surface tension of the organic solvent carrying the ink pigment or dye, and the difference in the amount of the droplet tends to appear as the difference in the surface shape of the droplet, particularly before the droplet is dried. . The controller 15 acquires information on the amount of the droplet based on the correlation between the surface shape of the droplet D and the received light intensity, luminance, and the like of the reflected light L2.

  FIGS. 6A and 6B are schematic diagrams for explaining the relationship between the surface shape of the droplet D and the reflected light L2 received by the light receiving unit 162, along the line BB ′ in FIG. FIG. Here, an example is shown in which a frame-shaped rib Sa defining the application region of the droplet D is formed on the surface of the substrate S. The light source 161 is arranged so that the illumination light L1 is incident on the droplet D to be measured from an oblique direction, and the optical axis of the light receiving unit 162 is fixed at a constant angle with respect to the substrate S. Is done.

  The surface of the droplet has a curved surface shape that protrudes upward due to the surface tension of the organic solvent before drying. The curvature of the droplet surface increases as the amount of droplet increases (the radius of curvature decreases), and the height of the droplet increases as the amount of droplet increases. As shown in FIG. 6A, the droplet D1 applied on the substrate S with a discharge amount smaller than the set value receives the reflected light L2 with a reflection intensity distribution corresponding to the surface shape according to the discharge amount. Reflects toward 162.

  On the other hand, as shown in FIG. 6B, the droplet D2 applied on the substrate S with a discharge amount larger than the set value has a larger curvature than the droplet D1, and thus the reflection intensity distribution of the reflected light L2 Is different from the case of the droplet D1. As a result, a difference occurs between the droplets D1 and D2 in the intensity of the reflected light L2 received by the light receiving unit 162, and the amount of the droplets D1 and D2 can be compared based on the difference in the reflected light intensity. .

  The positional relationship between the light source 161 and the light receiving unit 162 is not limited to the above example, and it is only necessary that the light source 161 and the light receiving unit 162 are arranged in such a positional relationship that a difference in the discharge amount of the droplet D1 can be determined. Further, the relationship between the ejection amount of the droplet D1 and the intensity of the reflected light L2 at the light receiving unit 162 is not particularly limited, and can be set as appropriate according to the positional relationship between the light source 161 and the light receiving unit 162. Accordingly, the positional relationship between the light source 161 and the light receiving unit 162 may be, for example, a relationship in which the intensity of the reflected light L2 increases as the ejection amount of the droplet D1 increases, and conversely, the droplet D1. The relationship may be such that the intensity of the reflected light L <b> 2 increases as the discharge amount decreases.

  In addition, the reflected light of the illumination light L1 incident on the light receiving unit 162 includes not only the reflected light L2 from the droplet D but also reflected light on the surface of the substrate S. When the surface reflected light of the substrate S incident on the light receiving unit 162 increases, the measurement accuracy of the reflected light L2 from the droplet D may be lowered. Therefore, in the present embodiment, as shown in FIG. 7, the light receiving unit 162 is disposed at an asymmetric position with respect to the light source 161 with respect to the axis Z <b> 1 (or plane) orthogonal to the surface of the substrate S. Thereby, since the regular reflection light L3 of the illumination light L1 on the surface of the substrate S can be suppressed from being received by the light receiving unit 162, the reflected light L2 from the droplet D can be accurately detected.

  For example, the light receiving unit 162 may be arranged so that the optical axis thereof coincides with the optical axis of the reflected light from the droplet applied with the set ejection amount. Or the light-receiving part 162 may be arrange | positioned in the position which does not receive the regular reflection light L3 in the board | substrate surface. Alternatively, a filter that cuts the regular reflected light L3 may be arranged on the light receiving surface of the light receiving unit 162.

  In addition, when the droplet D on the substrate S is not in an isotropic shape but has a shape having a longitudinal direction (major axis direction) in the Y-axis direction as shown in FIG. 5, a cross-sectional shape along the Y-axis direction. Compared to the cross-sectional shape along the X-axis direction, it is easier to determine the intensity change of the reflected light due to the droplet amount. Therefore, when the droplet D on the substrate S has shape anisotropy as described above, highly accurate droplet measurement is easily performed by evaluating the reflected light intensity on the surface along the minor axis direction. be able to.

  The controller 15 controls the movement of the light receiving unit 162 in the X-axis direction by the driving unit 17 and is based on the intensity of the reflected light L2 from the plurality of droplets ejected from the plurality of nozzles N and applied on the substrate S. , Information on the amount of the plurality of droplets is acquired. As a result, it is possible to compare the discharge amounts of the individual droplets. In addition, it is possible to acquire information about all the droplets on the substrate S with a single light receiving unit 162.

  The controller 15 controls the piezoelectric drive unit V of each nozzle N of the head units 121 to 126 based on the reflected light intensity of each droplet output from the light receiving unit 162.

  For example, when the received light intensity of the reflected light L2 is out of the reference range with respect to a certain droplet, the controller 15 controls the driving (for example, voltage waveform) of the piezoelectric driving unit V of the nozzle N that discharges the droplet. The amount of liquid droplets discharged from the nozzle N is adjusted so as to be within the reference range. The reference range can be appropriately set according to the type of ink, product specifications, and the like.

  As described above, in the present embodiment, the reflected light L2 of the illumination light L1 is received from the plurality of liquid droplets D in the liquid state immediately after printing, and the amount of liquid droplets ejected from each nozzle N is determined from the received light intensity. I am trying to measure. As a result, the calculation load on the controller can be reduced compared to a method in which the droplet discharged from the head unit is photographed on the flight path and imaged to measure the amount (volume) of the droplet. Droplet measurement in time is possible.

  Further, since the relative discharge amounts of the respective droplets are compared based on the received light intensity of the reflected light L2, measurement errors can be reduced, and more accurate discharge amount control is possible. In addition, the ejection amount can be optimized by promptly feeding back ejection defects to the head part, and inspections for unevenness of application and unevenness for all droplets on the substrate are performed. be able to. Thereby, stable printing can be continued and productivity can be improved.

  As described above, according to the present embodiment, compared to the method of measuring flying droplets, it is possible to perform precise droplet measurement without being affected by crosstalk between nozzles, and after drying. Compared with the method of measuring the film thickness of the coating film, it is possible to quickly feed back the ejection abnormality of the head portion.

  In addition, since the liquid amount measuring unit 16 is installed on the downstream side of the head module 12, it is possible to perform optical measurement in the liquid state before drying of each droplet D immediately after printing, thereby achieving high measurement accuracy. The discharge amount can be measured. For example, FIG. 8 schematically shows the state of the droplet D3 after drying. The dried droplets D3 are in a state where the organic solvent is evaporated and solidified, so that the surface has a substantially flat shape. In such a state, the difference in the surface shape based on the magnitude of the discharge amount is difficult to appear, so that the difference in the reflected light intensity cannot be detected, so that accurate liquid amount measurement is no longer possible.

  In the inkjet apparatus 1 according to the present embodiment, the light receiving unit 162 is configured to be relatively movable in the X-axis direction with respect to the stage 11, and therefore measurement conditions such as the light receiving direction of reflected light are set for each droplet. It can be shared, and a decrease in measurement accuracy due to a difference in measurement conditions and a variation in pixels of the light receiving unit 162 can be minimized. In addition, it is possible to measure the received light intensity with a plurality of droplets as one unit, and the processing time can be shortened. Furthermore, it can be easily applied to a large substrate.

  FIG. 9 shows an output example of the controller 15 related to the luminance of the reflected light L2 of the droplet D acquired by the light receiving unit 162. In the figure, the vertical axis represents the brightness of the reflected light (arbitrary unit), and the horizontal axis represents the number of image pixels acquired along the nozzle scan direction (X-axis direction in FIG. 5). Here, one pixel corresponds to one droplet D. Moreover, the range of the arrow on the horizontal axis represents the number of nozzles per head (64 nozzles).

  As shown in FIG. 9, a clear luminance change of the reflected light occurs for each pixel, and the difference between the maximum value and the minimum value corresponds to the magnitude of the luminance of the pixel. In the example shown in the figure, the difference between the maximum value and the minimum value of the luminance at each pixel corresponds to the difference between the light reception intensity of the droplet reflected light and the light reception intensity of the reflected light on the substrate surface, and the minimum value of the luminance is the substrate. It corresponds to the reflected light intensity (baseline) on the surface.

  As described above, according to the present embodiment, the shape of the droplet D can be easily grasped based on the luminance level of each pixel (droplet), and moreover, a plurality of pixels (droplets D) can be obtained. ), The variation in the shape of the droplet D can be grasped.

  Further, since the light receiving unit 162 is configured to be movable in a direction intersecting with the moving direction of the stage 11 (orthogonal in the present embodiment), the application of the droplet on the substrate and the measurement of the discharge amount of the droplet are the same. In addition, it is possible to perform on-line feedback control of the ink discharge amount.

  In the present embodiment, as feedback control of the ink discharge amount, the discharge amount is controlled for each nozzle so that the droplet reflected light intensity with respect to the baseline is constant. Thereby, it is possible to make the ink discharge amount constant between the plurality of nozzles.

  Further, a step of adjusting the light receiving sensitivity of the light receiving unit 162 may be performed for the purpose of improving the measurement accuracy of the liquid droplets by the liquid amount measuring unit 16. This adjustment step can be performed using the reflected light L2 of the illumination light L1 from the test droplets applied on the substrate S. An example is shown in FIG.

  In FIG. 10, the substrate S has a product region S <b> 10 for applying droplets D that form pixels and an adjustment region S <b> 20 for applying test droplets Ds. The adjustment area S20 is located upstream of the product area S10 in the transport direction of the substrate S. Ribs Sa are formed in the product area S10 for accommodating the droplets D discharged from the head portion, and ribs Sb are similarly formed in the adjustment area S20 for accommodating the droplets Ds.

  The adjustment region S20 measures the reflected light from a predetermined amount of the droplet Ds ejected in advance in the rib Sb by the liquid amount measurement unit 16, and sets the initial sensitivity of the light receiving unit 162, the threshold value, and the droplets. It is provided to perform highly accurate measurement or control. The initial setting is determined according to various conditions such as the liquid amount and type of the droplet Ds, and optical characteristics. Thereby, stable droplet measurement in the product region S10 can be realized.

  In the present embodiment, the rib Sb in the adjustment region S20 is formed to be narrower than the rib Sa in the product region S10. Therefore, when the same amount of droplet Ds as the droplet D supplied to the rib Sa is supplied to the rib Sb, the droplet Ds in the rib Sb rises higher than the droplet D in the rib Sa. Therefore, by arranging the light receiving unit 162 at a position where the light receiving intensity increases as the height of the liquid droplet from the substrate surface increases, the light receiving portion 162 is adjusted in the adjustment region S20 rather than the reflected light of the droplet D in the product region S10. The received light intensity of the reflected light of the droplet Ds can be increased. Therefore, compared with the case where droplets are measured and discharged on the product region S10, the droplets can be measured and controlled with higher accuracy.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the example in which the liquid amount measurement unit 16 is arranged on the downstream side of the head module 12 has been described, but the present invention is not limited thereto. For example, when ink having a long drying time is used, the liquid amount measurement unit 16 may be installed at a position farther from the head module 12 or installed on a base unit different from the base unit 10. Also good.

  Further, in addition to the liquid amount measuring unit 16, an image pickup unit for picking up images of droplets discharged from the head parts 121 to 126 during the flight, and an ink discharge surface 121s of the head parts 121 to 126 are cleaned. A blotting unit or the like may be provided.

DESCRIPTION OF SYMBOLS 1 ... Inkjet apparatus 11 ... Stage 15 ... Controller 16 ... Liquid quantity measuring unit 17 ... Drive part 121-126 ... Head part 161 ... Light source 162 ... Light-receiving part

Claims (13)

One or more heads capable of ejecting ink droplets;
A stage that supports the substrate to which the droplets are applied and is relatively movable along the first axial direction with respect to the head portion;
A light source capable of irradiating illumination light to the droplet on the substrate;
A light receiving unit capable of receiving reflected light of the illumination light from the droplet;
A controller capable of acquiring information on the volume of the droplet based on the intensity of the reflected light that is received by the light receiving unit and changes according to the curvature of the droplet surface ;
The controller is
Based on the brightness distribution of the reflected light acquired along the second axis direction intersecting the first axis direction, the maximum value and the minimum value of the brightness of the reflected light corresponding to each of the plurality of droplets Get
An inkjet apparatus that acquires a difference between the maximum value and the minimum value as information relating to a volume of the droplet . The inkjet apparatus according to claim 1,
A drive unit configured to be capable of moving the light receiving unit relative to the stage;
The head portion has a plurality of nozzles capable of discharging the droplets,
The controller controls the movement of the light receiving unit by the driving unit, and the plurality of droplets based on the intensity of the reflected light from the plurality of droplets ejected from the plurality of nozzles and applied onto the substrate. Inkjet device that obtains information on the volume of each. The inkjet apparatus according to claim 2,
The light-receiving unit includes a camera capable of simultaneously imaging the plurality of droplets applied on the substrate. An ink jet device according to claim 2 or 3,
The stage is configured to be relatively movable along the first axis direction with respect to the head portion,
It said controller, ink jet apparatus for controlling the driving unit so as to move along the light receiving portion in the second axis direction. An inkjet apparatus according to any one of claims 1 to 4,
The light receiving unit is disposed at an asymmetric position with respect to the light source with respect to an axis orthogonal to the surface of the substrate. An ink jet device according to any one of claims 1 to 5,
The head unit includes a plurality of head units arranged along a uniaxial direction. An ink jet device according to any one of claims 1 to 6,
The ink-jet apparatus configured to generate a control signal for controlling a discharge amount of the droplet based on information related to the volume of the droplet, and to output the control signal to the head unit. A first step of ejecting ink droplets from at least one head toward the substrate on the stage;
A second step of irradiating illumination light from a light source toward the droplets before drying applied to the substrate;
A third step of receiving a reflected light of the illumination light from the droplet by a light receiving unit;
A fourth step of acquiring information relating to the volume of the droplet based on the intensity of the reflected light that is received and changes according to the curvature of the droplet surface ;
Including
In the first step, a plurality of droplets are ejected from a plurality of nozzles of the head unit,
The third step receives reflected light from the plurality of droplets applied on the substrate while relatively moving the light receiving unit along the first axis direction with respect to the stage,
In the fourth step, the reflected light corresponding to each of the plurality of droplets is based on a luminance distribution of the reflected light acquired along a second axial direction intersecting the first axial direction. A droplet measurement method for acquiring a maximum value and a minimum value of luminance, and acquiring a difference between the maximum value and the minimum value as information relating to a volume of the droplet. The droplet measurement method according to claim 8, comprising:
The first step, ejecting the droplets while moving in the first axis direction said stage relative to said head portion,
The third step, the droplets measuring method for receiving the reflected light while the light receiving portion is moved along the second axial direction relative to the stage. The droplet measurement method according to claim 8 or 9 , further comprising:
A droplet measurement method that generates a control signal for controlling the ejection amount of the droplet based on information about the volume of the droplet, and outputs the control signal to the head unit. The droplet measurement method according to any one of claims 8 to 10 , further comprising:
A droplet measurement method for controlling a discharge amount of the droplet by using reflected light of the illumination light from a test droplet applied on the substrate. A droplet measurement method according to any one of claims 8 to 11 , comprising:
The substrate has a coating region surrounded by a regulation unit that regulates the area of the droplets to be constant,
The step of discharging the droplets is a droplet measurement method of discharging the droplets to the application region. A droplet measurement method according to claim 12 , comprising:
The application area has a longitudinal direction and a lateral direction,
The step of receiving the reflected light includes receiving the reflected light from the surface of the droplet along the lateral direction.

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