JP7442128B2 - Inkjet printing method and inkjet printing device - Google Patents

Description

The present invention relates to an inkjet printing device and a printing method using the same, and particularly to a method for adjusting the coating pitch of an inkjet head.

In recent years, methods of manufacturing devices using inkjet printing apparatuses have attracted attention. An inkjet printing device has a plurality of nozzles that eject droplets, and by ejecting droplets from the nozzles while controlling the positional relationship between the nozzles and the coating target portion of the printing target, the inkjet printing device Droplets are applied to the area. Some printing objects, such as display devices, have coating target areas arranged at a constant pitch.

In this case, by rotating an inkjet head in which multiple nozzles are arranged at a constant pitch around a rotation axis normal to the printing target surface, the pitch of the landed droplets is adjusted to the coating target area of the coating target. A method of coating according to the pitch is disclosed. (For example, Patent Document 1).

Japanese Patent Application Publication No. 2001-108820

This conventional method will be explained using FIGS. 14 and 15. FIG. 14 is a diagram showing the pitch of the coating target area and the positional relationship between the droplet discharge nozzle of the inkjet head, and FIG. 15 is a diagram showing the pitch of the conventional coating target area and the landing of droplets discharged from the inkjet head and landing on the substrate. FIG. 3 is a diagram showing an operation flow for adjusting pitch.

In FIG. 14, 108 is an inkjet head, 117 is a droplet discharge nozzle of the inkjet head 108, 119 is a substrate, 101 is a coating target area on the substrate 119, and 118 is a droplet that has landed on the coating target area 101. .

14A shows a case where the pitch W ₁ of the application target part 101 is equal to the pitch L of the droplet discharge nozzle 117, and FIG. 14B shows a case where the pitch W ₂ of the application target part 101 is equal to the pitch L of the droplet discharge nozzle 117. This represents a case where the pitch is smaller than the pitch L of the droplet discharge nozzles 117.

In FIG. 14, the inkjet head 108 and the substrate 119 are configured to eject droplets from the droplet ejection nozzle 117 while moving relative to each other in the X direction in the figure to apply the droplets to the application target portion 101. . As shown in FIG. 14(b), if the pitch _W2 of the coating target portion 101 is smaller than the pitch L of the droplet discharge nozzles 117, the inkjet head 108 is rotated by θ, and the droplet discharge nozzles 117 are aligned in the Y direction. The pitch can be matched to the pitch _W2 of the coating target portion 101.

In this conventional method, the operation of matching the pitch in the Y direction of the droplets 118 discharged from the droplet discharge nozzle 117 and landing on the substrate 119 with the pitch of the coating target portion 101 of the substrate 119 will be described with reference to FIG.

In FIG. 15, S1 "drawing a pattern for adjustment" is a step of applying a test pattern for droplet pitch measurement, S2 "inputting the drawn pattern using a sensor" is a step of capturing a test pattern with a camera, etc., and S3 is a step of applying a test pattern for measuring the droplet pitch. "Dot extraction processing" is a process of cutting out a droplet part from the data imported in S2, "dot centroid calculation processing" of S4 is a process of calculating the centroid of a droplet from the droplet data extracted in S3, "R pitch calculation, G pitch calculation, B pitch calculation" is a step of calculating the landing pitch of each of the landed droplets of R, G, and B from the center of gravity position of each of the landed droplets of R, G, and B obtained in S4, "Calculate pitch between RG and pitch between GB" calculates the landing pitch between RG and the landing pitch between GB from the centroid positions of each of the R landing droplet, G landing droplet, and B landing droplet extracted in S4. Step S7, "Are the pitches of each RGB droplet a predetermined distance?" is a step of determining whether the landing pitch of each of the R, G, and B droplets calculated in S5 is at the target distance. "Are the pitch between RG and the pitch between GB a predetermined distance?" is the step of determining whether the landing pitch between RG and the landing pitch between GB calculated in S6 is the target distance. "Adjust the Y-axis of the drawing head" is a process in which the position is adjusted by moving the drawing head in the Y direction when the landing pitch between RG and landing pitch between GB is not the target distance in S8, and the "adjusting the Y axis of the drawing head" in S10. "Adjusting the θ axis of" is a step of adjusting the θ rotation of the drawing head when the RGB landing pitches are not at the target distances in S7.

In this conventional method, a test pattern is printed in S1, the impact position of droplets of the test pattern is detected in S2 to S4, the impact pitch of each of R, G, and B is calculated in S5, and the impact pitch is calculated in S7. It is determined whether or not it matches the target value, and if it does not match, the θ rotation adjustment of the head is carried out in S10, and then the test printing is started again in S1. After the landing pitches of all R, G, and B match the target values, it is further determined in S8 whether the RG landing pitch and the GB landing pitch calculated in S6 match the target values. If not, the Y-axis adjustment is performed in S9, and then the test printing is performed again in S1.

As described above, in the conventional method, each time the pitch of the target coating area changes, a test print is performed, the landing pitch of the droplets is measured, and the rotation angle is further finely adjusted based on the results. , it was necessary to repeat the adjustment of the rotation angle and the Y direction until the target threshold value was reached. Even with this method, if the definition was low and the target threshold value was large, the adjustment could be made with one or two adjustments, and it did not pose much of a problem.

However, in recent years, as the demand for higher definition display devices has increased, the pitch of the coating target area has become smaller, and it has become necessary to align the landing pitch of droplets discharged from the nozzle very precisely. When coating such a high-definition display device, it is necessary to take into account slight deviations in the landing position due to the ejection angle of the droplets ejected from each nozzle, as well as changes in the landing position due to relative movement between the object to be coated and the inkjet head. Misalignment has come to have a large effect on coating position accuracy.

Therefore, when applying coating to a high-definition display device using the conventional method, it is necessary to stop the normal printing operation and perform the work to adjust the landing pitch many times each time the pitch of the coating target area changes. As a result, there was a problem in that the operating rate of the inkjet printing apparatus did not increase. Additionally, in order to improve the landing pitch, it was necessary to prepare a dedicated board for testing, or to provide a wide test printing area on the production board.

An object of the present invention is to determine the optimum amount of rotation of the head and adjust the droplet landing pitch and the target coating area without performing test printing each time the pitch of the coating target area of the coating object changes. An object of the present invention is to provide an inkjet printing method for accurately matching pitches, and an inkjet printing device using the same.

The main invention that solves the above-mentioned problems is as follows:
An inkjet printing method in which ink is applied onto the object by ejecting droplets from the inkjet head while scanning the inkjet head relative to the object, the method comprising:
A memory that stores landing position deviation characteristics determined based on landing position deviations of droplets ejected from the inkjet head from a target position when the inkjet head is at first and second rotation angles that are different from each other. a first step of reading data related to the landing position deviation characteristics from the means;
A target rotation angle of the inkjet head is determined based on the landing position deviation characteristic, an arrangement pitch of droplet discharge nozzles of the inkjet head, and a target coating pitch of the coating object in a direction orthogonal to the scanning direction. and a second step of generating a printing pattern corresponding to the target rotation angle;
a third step of controlling the inkjet head based on the target rotation angle and the printing pattern to eject droplets to a coating target portion on the coating object;
This is an inkjet printing method.

Also, in other situations,
An inkjet printing device that applies ink onto the object by discharging droplets from the inkjet head while scanning the inkjet head relative to the object, comprising:
A memory that stores landing position deviation characteristics determined based on landing position deviations of droplets ejected from the inkjet head from a target position when the inkjet head is at first and second rotation angles that are different from each other. means and
A target rotation angle of the inkjet head is determined based on the landing position deviation characteristic, an arrangement pitch of droplet discharge nozzles of the inkjet head, and a target coating pitch of the coating object in a direction orthogonal to the scanning direction. and a calculation means for generating a printing pattern corresponding to the target rotation angle;
Equipped with
The inkjet printing apparatus controls the inkjet head based on the target rotation angle and the printing pattern to eject droplets onto a coating target portion on the coating object.

According to the aspect of the present invention, even if the pitch of the coating target part of the coating object changes, the landing pitch of droplets ejected from the inkjet head can be adjusted to the coating target without having to perform test printing each time. It can be adjusted to the pitch of the part.

A perspective view of an inkjet printing device according to an embodiment A plan view showing a substrate of an object to be coated according to an embodiment A plan view illustrating the landing position deviation due to the ejection angle of droplets ejected from an inkjet head. Side view illustrating the landing position deviation due to the ejection angle of droplets ejected from an inkjet head A plan view illustrating the landing position deviation due to droplet ejection angle habits when the inkjet head has a rotation angle of 0 degrees. A plan view illustrating the landing position deviation due to droplet ejection angle habits when the inkjet head rotates at a rotation angle of φ degrees. A plan view illustrating the landing position of droplets ejected from an inkjet head when the object to be coated is stationary. Side view illustrating the landing position of droplets ejected from the inkjet head when the object to be coated is stationary A plan view illustrating the landing position of droplets ejected from the inkjet head when the object to be coated is moving. Side view illustrating the landing position of droplets ejected from the inkjet head when the object to be coated is moving A plan view illustrating the landing position of ejected droplets when the rotation angle of the inkjet head is 0 degrees when the object to be coated is moving. A plan view illustrating the amount of positional deviation in the Y direction between the landing position of ejected droplets and the coating target portion of the coating target when the coating target is traveling and the rotation angle of the inkjet head is 0 degrees. A plan view illustrating the distance in the X direction between the landing position of ejected droplets and the Y axis when the coating target is traveling and the rotation angle of the inkjet head is 0 degrees. A plan view illustrating the landing position when the ejection timing is corrected so that the landing position when the inkjet head rotation angle is 0 degrees is on the Y axis when the object to be coated is traveling. A plan view illustrating the landing position of droplets when printing on an object to be coated with the ejection timing corrected so that the landing position is on the Y-axis at a rotation angle of 0 degrees of the inkjet head. Enlarged view of part A in Figure 8d A plan view illustrating the amount of positional deviation in the Y direction between the landing position of the ejected droplet and the coating target portion of the coating target when the coating target is traveling and the rotation angle of the inkjet head is θ. A plan view illustrating the distance in the X direction between the landing position of the ejected droplet and the Y axis when the coating target is traveling and the rotation angle of the inkjet head is θ. A plan view illustrating the landing position when the ejection timing is corrected so that the landing position is on the Y axis when the rotation angle of the inkjet head is θ when the object to be coated is traveling. A plan view illustrating the landing position of droplets when printing on an object to be coated with the ejection timing corrected so that the rotation angle of the inkjet head is θ and the landing position is on the Y axis. Enlarged view of part A in Figure 9d A plan view illustrating the amount of positional deviation in the Y direction between the landing position of the ejected droplet and the coating target portion of the coating target when the coating target is traveling and the rotation angle of the inkjet head is φ. A plan view illustrating the distance in the X direction between the landing position of the ejected droplet and the Y axis when the object to be coated is traveling and the rotation angle of the inkjet head is φc. A plan view illustrating the landing position when the ejection timing is corrected so that the landing position is on the Y-axis when the rotation angle of the inkjet head is φc when the object to be coated is traveling. A plan view illustrating the landing position of droplets when coating the object with the rotation angle of the inkjet head being φc and the ejection timing corrected so that the landing position is on the Y axis. Enlarged view of part A in Figure 10d A plan view illustrating the landing position before and after the θ rotation of the inkjet head when the coating target is scanned at a speed V. A plan view illustrating the landing position when the inkjet head is rotated by φ when the object to be coated is scanning at a speed V A plan view illustrating the landing position before and after the θ rotation of the inkjet head when the object to be coated is stationary. A diagram illustrating a conventional example in which an inkjet head is adjusted to match the pitch of a coating target portion of an object to be coated. Flowchart for adjusting the pitch of the coating target part of the coating object and the pitch of droplets ejected from the inkjet head in a conventional example

The inkjet printing device 40 according to the present embodiment will be described below with reference to the drawings.

[Configuration of inkjet printing device]
FIG. 1 is a perspective view of an inkjet printing apparatus according to one embodiment. The overall image of the inkjet printing device 40 will be explained with reference to FIG.

As shown in FIG. 1, the inkjet printing device 40 includes at least a pedestal 18 that supports the device, a surface plate 17 installed on the pedestal 18, and a substrate conveyance stage installed on the surface plate 17 that conveys a substrate in the X direction. 30, a head unit 32, a head unit transfer stage 33 that transfers the head unit 32 in the Y direction orthogonal to the substrate transfer stage 30, and two that support both ends of the head unit transfer stage 33 on the surface plate 17. The support part 16 is provided.

The substrate transfer stage 30 includes a substrate guide rail 5, a substrate slider 4 that is guided by the substrate guide rail 5 and supported slidably in the X direction, and a substrate rotation mechanism 3 installed on the substrate slider 4. and a substrate suction table 2 installed on a substrate rotation mechanism 3. The substrate transfer slider 4 is feedback-controlled by a substrate transfer linear motor 6, a substrate transfer position detection means 7, and a substrate transfer stage control means (not shown).

Further, the substrate rotation mechanism 3 is equipped with a substrate rotation angle detection means (not shown) and a substrate rotation drive means (not shown), and is configured to be able to accurately position the substrate at a target rotation angle by means of a substrate rotation mechanism control means (not shown). are doing.

On the other hand, the head unit transfer stage 33 includes a head unit transfer guide rail 13 and a head unit transfer slider 12 that is guided by the head unit transfer guide rail 13 and supported slidably in the Y direction. The head unit transfer slider 12 is feedback-controlled by a head unit transfer linear motor 14, a head unit transfer position detection means 15, and a head unit transfer stage control means (not shown). ing.

The head unit 32 includes an inkjet head section 23 and an alignment camera 21 mounted on a head unit base 22 attached to the head unit transfer slider 12. Further, in the inkjet head section 23, a head rotation mechanism 10 is mounted on the head unit base 22 via a bracket 11, and an inkjet head 8 is mounted below the head rotation mechanism 10 via a head bracket 9. The head rotation mechanism 10 is internally equipped with a head rotation angle detection means (not shown) and a head rotation drive means (not shown), and is configured such that it can be accurately positioned at a target rotation angle by a head rotation mechanism control means (not shown). has been done.

Furthermore, the inkjet head 8 is provided with a plurality of droplet discharge nozzles, and the inkjet head control means 100 determines, for each droplet discharge nozzle of the inkjet head 8, based on the detected position by the substrate conveyance position detection means 7. It is configured so that the discharge timing can be controlled. Note that the plurality of droplet discharge nozzles of the inkjet head 8 are arranged, for example, in a line at a predetermined pitch.

The inkjet head control means 100 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, an output port, etc., and controls the ejection operation of the inkjet head 8. It is a microcomputer that controls it.

The inkjet head control means 100 includes a storage means 110 that stores the landing position deviation characteristics when droplets are ejected from the inkjet head 8, the landing position deviation characteristics, the arrangement pitch of the droplet ejection nozzles of the inkjet head 8, and a calculation means 120 for determining a target rotation angle of the inkjet head 8 based on the target coating pitch of the coating object in a direction perpendicular to the scanning direction, and generating a print pattern corresponding to the target rotation angle. . Note that the landing position deviation characteristic is determined based on the landing position deviation of the droplet ejected from the inkjet head 8 from the target position when the inkjet head 8 is rotated at different first and second rotation angles. (Details will be described later).

In the first embodiment, both the substrate transfer stage 30 and the head unit transfer stage 33 employ air bearing mechanisms in order to achieve highly accurate positioning.

[Operation of inkjet printing device]
Next, the operation of the inkjet printing apparatus 40 having the above configuration will be explained using FIGS. 2 to 13. FIG. 2 is a plan view showing a substrate to be coated according to the first embodiment. The substrate 1 is surrounded by the equipment 1a, the alignment marks 1b formed at the four corners of the equipment 1a, and the banks 1c, which serve as embankments to prevent the printed ink from overflowing, and are arranged at a constant pitch. It consists of a coating target area 1d and a test printing area 1e for measuring the droplet landing position, and the landing measurement area 1f in the test printing area 1e is an extension of 1d with the same pitch as the coating target area 1d. It is formed on a line. The coating target area 1d is an area that constitutes a pixel of the display panel, and the landed droplets wet and spread, whereas the landing measurement area 1f is made to have liquid repellency so that the landed droplets stay in a circular shape. Then, the position of the impact measurement area 1f relative to the center of the circle can be measured by capturing an image of the position using the alignment camera 21 and processing the image using an image processing means (not shown).

The application area 1g is a liquid-repellent area similar to the impact measurement area 1f, and is used to measure the approximate impact position of the droplet when the droplet does not fall within the circle of the impact measurement area 1f. It is set up for use as an area.

<When the substrate 1 and inkjet head 8 do not move relative to each other>
Next, regarding the relationship between the position of the droplet discharge nozzle of the inkjet head 8 and the landing position at which the droplet discharged from the droplet discharge nozzle reaches the substrate 1 when the substrate 1 and the inkjet head 8 do not move relative to each other. This will be explained with reference to FIGS. 3a, 3b, 4a, and 4b.

FIG. 3a is a plan view illustrating the landing position deviation due to the ejection angle of droplets ejected from the inkjet head 8, and FIG. 3b is a side view.

FIG. 4a is a plan view illustrating the landing position deviation due to the droplet ejection angle when the rotation angle of the inkjet head 8 is 0 degrees, and FIG. 4b is a plan view of the droplet when the rotation angle of the inkjet head is φ degrees. FIG. 3 is a plan view illustrating a landing position shift due to a discharge angle.

The inkjet head 8 in FIG. 3A has four droplet ejection nozzles indicated by dotted circles, and the hole positions are designated as n ₁ , n ₂ , n ₃ , and n ₄ . Each droplet discharge nozzle has its own characteristic in the direction of discharge, and when the droplets land on the surface of the substrate 1 that is a distance G away from the nozzle surface of the inkjet head 8 as shown in FIG. 3b, the position is indicated by a solid circle. As shown in P ₁ , P ₂ , P ₃ , and P ₄ , it reaches a position different from directly below n ₁ , n ₂ , n ₃ , and n ₄ . This amount of positional deviation will be referred to as a landing position deviation due to the ejection angle.

The landing position deviation due to the ejection angle from each droplet ejection nozzle is determined by the shape accuracy of the hole of the droplet ejection nozzle and the surface condition around the droplet ejection nozzle. It becomes a habit. Therefore, compared to when the rotation angle of the inkjet head 8 is 0 degrees like the inkjet head 8 shown in FIG. 4a, even when the rotation angle is turned by φ degrees as shown in FIG. 4b, the droplet ejection of the head is The landing positions P ₁ , P ₂ , P ₃ , and P ₄ are shifted in the same direction within the inkjet head 8 with respect to the nozzle positions n ₁ , n ₂ , n ₃ , and n ₄ . That is, FIG. 4b, which is a plan view when the inkjet head 8 is rotated by φ degrees, is in a position obtained by rotating FIG. 4a by φ degrees. Note that the point O in FIGS. 4a and 4b is the rotation axis.

<When the substrate 1 and the inkjet head 8 move relative to each other>
Next, while the substrate 1 is traveling at a constant speed V with respect to the inkjet head 8, the landing position when a droplet is ejected from the droplet ejection nozzle of the inkjet head 8 toward the substrate 1 is shown in FIGS. 5a, 5b, This will be explained with reference to FIGS. 6a and 6b.

FIG. 5a is a plan view illustrating the landing position deviation of droplets ejected from the inkjet head 8 when the object to be coated is stopped, and FIG. 5b is a side view thereof. FIG. 6a is a plan view illustrating the landing position deviation of droplets ejected from an inkjet head when the object to be coated is traveling at a speed V, and FIG. 6b is a side view thereof.

The position where a droplet ejected from the nozzle at the _n1 position of the inkjet head 8 lands on the substrate 1 when the substrate 1 is stopped as shown in FIG. 5a is defined as _P1 . The amount of positional deviation of P ₁ with respect to n ₁ is the landing position deviation due to the ejection angle habit explained with reference to FIG. 4 . On the other hand, a droplet discharged from the nozzle at the _n1 position while traveling on the substrate 1 at a constant speed V flies with a certain velocity, so it takes time for the droplet to reach the substrate 1. . If that time is Δt, the substrate travels by Δt×V during that time, so the landing position _Q1 of the droplet on the substrate 1 is relative to the landing position _P1 when the droplet lands on the substrate 1 in a stopped state. It will shift.

In reality, while the droplets are flying toward the substrate 1, they are slowed down by air resistance, and the droplets are blown away by the wind generated by the movement of the substrate 1, so they have to be placed in even more complicated positions. This will result in a misalignment. The landing position deviation ΔX _1v in the running direction caused by the running of the substrate 1 will be referred to as the landing position deviation due to running. The landing position deviation due to this movement is the landing position deviation due to the movement of the substrate 1, and is basically a position deviation that occurs in the running direction. Even when the inkjet head 8 is rotated, it does not rotate together with the rotation of the inkjet head 8.

As explained above, when the substrate 1 is stopped, the landing position of the droplet ejected from the nozzle position _n1 on the substrate 1 will be _P1 , which is only the landing position deviation due to the ejection angle. On the other hand, when the substrate is traveling at a speed V, the droplet lands at a position that is calculated by adding the landing position shift ΔX1v due to traveling in the traveling direction of the substrate 1 to _P1 , which is shifted due to the ejection angle. do.

Next, a method for printing droplets on the coating target portion 1d of the substrate 1 will be described.

(1) First, a method for aligning the substrate 1 will be explained. The substrate 1 is suctioned and fixed on the substrate suction table 2, and the substrate transfer stage 30 and head unit transfer stage 33 are moved to align the alignment marks 1b at the four corners of the substrate 1 under the alignment camera 21 mounted on the head unit 32. The alignment mark 1b is imaged by the alignment camera 21, and the position of the alignment mark 1b is measured by an image recognition means (not shown). On the other hand, based on the detected position by the substrate transport position detection means 7 and the detection position by the head unit transfer position detection means 15 at that time, a control means (not shown) determines the traveling direction of the substrate transport stage 30 and the coating target of the substrate 1. The substrate rotation mechanism 3 is driven and adjusted so that the directions of the portions 1d are parallel.

(2) Next, a method for adjusting the position of the droplet discharge nozzle and the coating target portion 1d of the substrate 1 will be explained. FIG. 7 is a plan view illustrating the landing position of ejected droplets when the inkjet head is at the first rotation angle (rotation angle 0 degrees here) when the object to be coated travels at a speed V.

Dotted-line circles n ₁ , n ₂ , n ₃ , n ₄ in FIG. 7 are the positions of the droplet ejection nozzles in the inkjet head 8, and solid-line circles P ₁ , P ₂ , P ₃ , P ₄ are the positions of the droplet discharge nozzles in the inkjet head 8. The droplets discharged from the droplet discharge nozzle represent the landing positions that are shifted when they reach the substrate 1 due to the discharge angle, and the double solid circles Q ₁ , Q ₂ , Q ₃ , and Q ₄ are P ₁ , P ₂ , _P3 , and _P4 , the landing position is calculated by adding the landing position shift caused by the traveling of the substrate 1. In FIG. 7, the inkjet head 8 is positioned at a rotation angle of 0 degrees around the rotation axis O so that the droplet pitch in the Y direction of the inkjet head 8 matches the pitch _W0 of the coating target portion 1d.

<Calculation of impact position deviation characteristics>
Next, a method for calculating the landing position deviation characteristics (hereinafter abbreviated as "landing position deviation characteristics") that occurs when the inkjet printing device 40 discharges droplets from the inkjet head 8 will be described.

FIG. 8a shows the landing position of the ejected droplet and the coating target portion 1d of the coating object in the state shown in FIG. FIG. 3 is a plan view illustrating the amount of displacement in the Y direction. In FIG. 8a, the distances in the Y direction between the Y direction positions of droplet landing positions Q ₁ , Q ₂ , Q ₃ , and Q ₄ and the central axis of the coating target area 1 d are ΔY ₁₀ , ΔY _{20 , ΔY 30 ,} and ΔY , respectively. It is expressed in ₄₀ . The inkjet head 8 and the substrate 1 are aligned in the Y direction so that the total errors of ΔY ₁₀ , ΔY ₂₀ , ΔY ₃₀ , and ΔY ₄₀ are minimized.

FIG. 8b shows the distance in the X direction between the landing position of the ejected droplet and the Y axis when the object to be coated is traveling at a speed V and the rotation angle of the inkjet head 8 is 0 degrees in the state shown in FIG. FIG. 3 is a plan view for explanation. In FIG. 8b, the distances in the X direction from the Y axis to the droplet landing positions Q ₁ , Q ₂ , Q ₃ , and Q ₄ are represented by X _1S0 , X _2S0 , X _3S0 , and X _4S0 . FIG. 8c shows the landing position when the ejection timing corresponding to the distances X _1S0 , X _2S0 , X _3S0 , and X _4S0 in the X direction is corrected. By adjusting the ejection timing as shown in FIG. 8c, the landing positions of the droplets ejected from all droplet ejection nozzles and reaching the substrate 1 can be aligned approximately on the Y axis. This printing pattern is defined as a first printing pattern. FIG. 8d shows the landing position when printing is performed on the landing measurement area 1f and coating target portion 1d of the substrate 1 in this state. This printing is referred to as the first printing process. In FIG. 8d, the droplets in the coating target area 1d are also indicated by double circles, but in reality, the coating target area 1d is hydrophilic, so the landed droplets will spread by wetting. On the other hand, since the landing measurement area 1f is liquid repellent, the landed droplets land in a circular shape within the circle surrounding the landing measurement area 1f, as shown in FIG. 8d. FIG. 8e is an enlarged view of section A in FIG. 8d. By capturing an image of this landing measurement area 1f with the alignment camera 21 and performing image processing, the positional deviation ΔY _i0 in the Y direction between the circle in the landing position measurement area 1f with pitch W ₀ and the circle of the droplet and the position in the X direction By detecting the deviation ΔX _i0 (i=1, 2, 3, 4), the landing position deviation of the droplet can be accurately measured. This measurement is referred to as a first landing position deviation detection step.

As a result, from the landing position deviation measurement results in the above landing measurement area 1f, ΔX _i0 , ΔY _i0 , and the correction amount X _iS0 shifted by the ejection timing correction in FIG. Position can be calculated accurately. This calculation process is referred to as a first landing position calculation process. This landing position data is then set as first landing position data.

Next, when the pitch of the target coating area _1d is W1, which is smaller than _W0 , a case will be explained in which the inkjet head 8 is rotated by θ around the rotation axis O point so that the droplet pitch matches _W1 . do.

FIG. 9a shows the landing position of the ejected droplet and the coating target of the coating target when the inkjet head 8 is at the second rotation angle (rotation angle θ degrees here) when the coating target runs at a speed V. FIG. 7 is a plan view illustrating the amount of positional deviation in the Y direction with respect to the portion 1d. The distances in the Y direction between the droplet landing positions Q ₁ , Q ₂ , Q ₃ , and Q ₄ in the Y direction and the central axis of the coating target portion 1d are expressed as ΔY _1θ , ΔY _2θ , ΔY _3θ , and ΔY _{4θ ,} respectively. There is. The inkjet head 8 and the substrate 1 are aligned in the Y direction so that the total error of ΔY _1θ , ΔY _2θ , ΔY _3θ , and ΔY _4θ is minimized.

FIG. 9b illustrates the distance in the X direction between the landing position of the discharged droplet and the Y axis when the rotation angle of the inkjet head 8 is θ in the state shown in FIG. 9a, that is, when the object to be coated travels at a speed V. FIG.

The distances in the X direction from the Y axis to the droplet landing positions Q ₁ , Q ₂ , Q ₃ , and Q ₄ are expressed as X _1Sθ , X _2Sθ , X _3Sθ , and X _4Sθ . FIG. 9c shows the landing position when the ejection timing corresponding to the distances X _1Sθ , X _2Sθ , X _3Sθ , and X _4Sθ in the X direction is corrected. By adjusting the ejection timing as shown in FIG. 9c, the landing positions of the droplets ejected from all the droplet ejection nozzles and reaching the substrate 1 can be aligned approximately on the Y axis. This printing pattern is defined as a second printing pattern. FIG. 9d shows the landing position when printing is performed on the landing measurement area 1f and coating target portion 1d of the substrate 1 in this state. This printing is referred to as a second printing process. In FIG. 9d, the droplets in the coating target area 1d are also indicated by double circles, but in reality, the coating target area 1d is hydrophilic, so the landed droplets will spread by wetting. On the other hand, since the landing measurement area 1f is liquid repellent, the landed droplets land in a circular shape within the circle surrounding the landing measurement area 1f, as shown in FIG. 9d. FIG. 9e is an enlarged view of section A in FIG. 9d. By imaging this landing measurement area 1f with the alignment camera 21 and performing image processing, it is possible to determine the positional deviation ΔY _iθ in the Y direction between the circle in the landing position measurement area 1f with pitch W ₁ and the circle of the droplet, and the position in the X direction. By detecting the deviation ΔX _iθ (i=1, 2, 3, 4), the landing position deviation of the droplet can be accurately measured. This measurement is referred to as a second landing position deviation detection step.

As a result, from the landing position measurement results in the above landing measurement area 1f, ΔX _iθ , ΔY _iθ , and the correction amount X _iSθ shifted by the ejection timing correction in FIG. can be calculated accurately. This calculation process is referred to as a second landing position calculation process. This landing position data is then set as second landing position data.

Note that the relative movement speed between the inkjet head 8 and the substrate 1 in the first printing process and the relative movement speed between the inkjet head 8 and the substrate 1 in the second printing process are set to be the same.

As described above, by rotating the inkjet head 8 by θ degrees, the pitch of the droplets is adjusted to the pitch of the coating target portions for a substrate where the pitch of the coating target portions 1d is W ₀ and a substrate where the pitch of the coating target portions 1d is W ₁ . Print according to the pitch and accurately measure the landing position of each bullet.

Then, based on the measurement results of the landing positions on the two types of substrates 1 mentioned above, the optimum rotation angle of the inkjet head 8 that minimizes the landing deviation for a substrate with an arbitrary target coating pitch is calculated, and test printing is performed. This makes it possible to apply the product without removing it.

The method will be explained with reference to FIGS. 11 and 12.

FIG. 11 is a diagram showing the relationship between the landing positions of one nozzle in the inkjet head 8 when the rotation angle is 0 degrees around the head rotation center point O and when the nozzle is rotated by θ degrees from there. Here, let the X coordinate of the head rotation center point O be δx, and the Y coordinate be δy. Further, the landing position when the rotation angle is 0 degrees is Q ₀ , the X coordinate of Q ₀ is Xa, the Y coordinate is Ya, and it is written as Q ₀ (Xa, Ya). On the other hand, the landing position when the rotation angle is θ degrees is Q _θ , the X coordinate of Q _θ is Xb, the Y coordinate is Yb, and it is written as Q _θ (Xb, Yb). Furthermore, the displacement of the landing position in the X direction due to the movement of the substrate 1 is defined as _ΔXV .

When coating while the substrate 1 is running, the landing position deviation of the droplets ejected from the inkjet head 8 and landing on the substrate 1 is due to the landing angle peculiarity when the droplets are ejected from the droplet ejection nozzle, as described above. The landing position deviation due to the movement of the substrate 1 is added to the position deviation, and the landing position deviation due to the ejection angle rotation rotates with the rotation of the inkjet head 8, and the landing position deviation due to the movement of the substrate 1 is due to the rotation of the inkjet head 8. It is determined by the running direction of the substrate 1, regardless of the current direction. Therefore, the landing positions P ₀ and P _θ due only to the ejection angle peculiarities for the rotation angles of 0 degrees and θ degrees of the inkjet head 8 are respectively such that the X coordinate of P ₀ is Xa - ΔX _V , the Y coordinate is Ya, and P _θ The X coordinate of is Xb-ΔX _V and the Y coordinate is Yb.

Since P _θ corresponds to the position where P ₀ is rotated by θ degrees around the head rotation axis O point, the relationship between the P _θ point and the P ₀ point is expressed by equations (1) and (2) according to the coordinate rotation equation. It can be expressed as

From equations (1) and (2), the Y coordinate δy of the rotation axis of the inkjet head 8 and the positional deviation _ΔXV due to the movement of the substrate 1 can be determined as shown in equations (3) and (4). can. Here, the X-axis coordinate δx of the rotation axis of the inkjet head 8 needs to be measured separately. The measurement method will be explained later.

If the X-coordinate δx of the head rotation center O of the inkjet head 8 is determined in advance as described above, in the method of printing while the substrate 1 is traveling at the speed V, the rotation angle of the inkjet head 8 will be 0 degrees ( Impact position Q ₀ (Xa, Ya) (first impact position data), Q _θ (Xb, Yb) (first rotation angle) and θ degrees (second rotation angle) By measuring the landing position data (No. 2), the landing position deviation ΔX _V due to the traveling of the substrate can be determined, and once ΔX _V is determined, the landing position deviation due to the ejection angle habit can be determined. This calculation process is referred to as a landing position deviation characteristic calculation process.

The data related to the landing position deviation characteristics calculated in this manner are stored in the storage means 110 as data indicating the unique characteristics of the inkjet head 8 used here. In addition, the droplet ejection operation for calculating the landing position deviation characteristic is performed by, for example, applying a droplet to the landing measurement area 1f at the same time when printing the coating target area 1d. This can be done by measuring the landing position deviation.

<Operation when printing>
The inkjet printing device 40 (calculating means 120) uses the landing position deviation characteristics calculated above to determine a target rotation angle of the inkjet head 8 during printing, and also calculates a print pattern corresponding to the target rotation angle. generate. In the present embodiment, when a droplet is ejected from each droplet ejection nozzle of the inkjet head 8, the rotation angle at which the positional shift of the coating target portion 1d of the coating object is minimized is set to the rotation angle of the inkjet head at the time of printing. 8 (hereinafter also referred to as "optimal rotation angle"). However, the target rotation angle of the inkjet head 8 is set to a rotation angle such that when droplets are ejected from each droplet ejection nozzle of the inkjet head 8, the positional deviation of the coating target portion 1d of the coating object is equal to or less than a threshold value. It's okay.

First, from the landing position deviation characteristics determined above (that is, the landing position deviation ΔX _V due to the movement of the substrate 1 and the landing position deviation due to the ejection angle) and the head rotation center O (δx, δy) of the inkjet head 8. 12, a method of calculating the landing position at an arbitrary third rotation angle φ of the inkjet head 8 in a method of printing while moving the substrate 1 at a speed V will be described with reference to FIG.

FIG. 12 is a diagram illustrating the landing position shift when the inkjet head 8 has a head rotation angle of 0 degrees and when the head rotation angle is φ degrees.

First, the calculation means 120 reads data related to the landing position deviation characteristics stored in the storage means 110, and calculates the landing position by traveling from the X coordinate of the landing position Q ₀ (Xa, Ya) at a rotation angle of 0 degrees of the inkjet head 8. By subtracting the positional deviation ΔX _V , the landing position P ₀ (Xa−ΔX _V , Ya) in the case where there is only the ejection angle quirk is determined. Then, the calculating means 120 calculates the landing position P _φ (Xd, Yd) when there is only the ejection angle quirk by rotating the P ₀ point by φ degrees around the head rotation center O point, and calculates the landing position P φ (Xd, Yd) of the P _φ point. The landing position Q _φ (Xe, Ye) at the rotation angle φ is determined by adding the landing position deviation ΔX _V due to the movement of the substrate 1 to the rotation angle φ. Expressing this in equations, the coordinates of the P _φ point can be expressed by equations (5) and (6), and the coordinates of the Q _φ point can be expressed by equations (7) and (8). The step of calculating the landing position at the third rotation angle φ of the inkjet head 8 described above is referred to as the landing position prediction step.

Note that the calculation means 120 variously changes the third rotation angle φ of the inkjet head 8 and calculates the landing position at each of the plurality of third rotation angles φ.

Next, the calculation means 120 calculates the amount of liquid on the object to be coated based on the arrangement pitch of the droplet discharge nozzles of the inkjet head 8 and the target coating pitch of the target portion 1d of the object to be coated in the direction orthogonal to the scanning direction. The optimal rotation angle φc of the inkjet head 8 when ejecting droplets from the inkjet head 8 with respect to the coating target portion 1d is determined. The calculation means 120 calculates, for example, an evaluation value related to the landing position shift of the droplet with respect to the coating target portion 1d at each of the plurality of third rotation angles φ of the inkjet head 8, and uses this evaluation value as a reference to determine the optimal Find the rotation angle φc.

Formulas for calculating the landing position of one droplet discharge nozzle at the rotation angle φ of the inkjet head 8 are shown in formulas (7) and (8). Here, in the case where the inkjet head 8 is provided with a plurality of droplet discharge nozzles, the landing position coordinates of the i-th droplet discharge nozzle at a rotation angle of 0 degrees (first rotation angle) of the inkjet head 8 are (X _ia , Y _ia ), the landing position coordinates at the rotation angle θ degrees (second rotation angle) are (X _ib , Y _ib ), and the amount of positional deviation due to the running of the i-th nozzle is ΔX _iv , then the rotation angle φ( If the impact position coordinates at the third rotation angle are (X _ie , Y _ie ), the values can be expressed as in equations (9) and (10).

Here, ΔX _iv can be expressed by equation (11). If the Y coordinate of the coating target part of the i-th droplet discharge nozzle is Y _ti and the Y coordinate of the landing position of the i-th droplet discharge nozzle is Y _ie , then the difference ΔY _iφ is expressed by equation (12). be able to. This ΔY _iφ and ΔX _iv are shown in FIG. 10a. In each figure, i indicates four droplet discharge nozzles 1, 2, 3, and 4. Then, in order to obtain the optimal rotation angle φc of the inkjet head 8, the calculation means 120 uses the average sum of squares Δt of the Y-direction positional deviations _ΔYiφ of all droplet ejection nozzles as an evaluation value, as shown in equation (13). calculate. Then, the calculation means 120 changes φ, calculates the average sum of squares Δt for each φ, and finds the value of φ that minimizes Δt. φ at which this Δt is minimum becomes the optimum rotation angle φ _C of the inkjet head 8.

Furthermore, the calculation means 120 calculates the offset amount Δy in the Y direction using equation (14). This Δy is reflected in printing by offsetting the substrate 1 and the inkjet head 8 during alignment.

In the X direction, the calculating means 120 calculates the landing position coordinate X _ieφc of each nozzle in the X direction using equation (15), and corrects the ejection timing by an amount corresponding to −X _ieφc . The print pattern whose ejection timing has been corrected will be referred to as an optimal print pattern, and the process of generating it will be referred to as an optimal print pattern generation process.

In addition, when the rotation angle of the inkjet head 8 is set to the optimal rotation angle _φC , the landing position coordinate _Yieφc of each nozzle in the Y direction is calculated by equation (16), and the positional deviation in the Y direction from the target coordinate is calculated by Equation (16). _ΔYieφc is calculated using equation (17). Then, the Y coordinate of the landing position when considering the offset in the Y direction is Y _ieφc -Δy.

The inkjet printing device 40 (inkjet head control means 100) positions the inkjet head 8 at the optimum rotation angle φ _c calculated above and the offset amount Δy in the Y direction, and prints according to the above optimum printing pattern. Thereby, droplet discharge can be performed such that the positional deviation with respect to the coating target portion 1d is minimized.

Note that during this printing, the inkjet printing device 40 moves the substrate transport stage so that the relative movement speed between the inkjet head 8 and the substrate 1 is the same as the speed in the above-described first printing process and second printing process. Control 30.

The above situation is shown in FIGS. 10b to 10e. FIG. 10b shows the distance in the X direction between the landing position of each droplet discharge nozzle No. 1, 2, 3, and 4 and the Y axis when the head rotation angle of the inkjet head 8 is set to the optimum rotation angle φ _c determined above. FIG. FIG. 10c is a diagram showing the landing position when the ejection timing is corrected by the distance in the X direction between the landing position of each droplet ejection nozzle in FIG. 10b and the Y axis. If the ejection timing is corrected by the amount calculated using equation (15) in the opposite direction _-XieΦc , the landing positions of each droplet ejection nozzle will overlap on the Y axis. FIG. 10d shows a diagram in which droplets are applied to the substrate 1 in this state. By setting the rotation angle of the inkjet head 8 to the optimum rotation angle φc, the positional deviation between the landing position of each nozzle and the coating target position is minimized. FIG. 10e shows an enlarged view of the landing position in the landing measurement area 1f when actually applied. This figure shows the landing positions of droplets discharged from the third and fourth droplet discharge nozzles in the landing measurement area. The positional deviation amount ΔX _3φc , ΔX _4φc from the target position of the actually landed droplet in the It is also possible to make it even smaller by performing correction.

<How to find the coordinates of the center of rotation of the inkjet head>
Next, a method of determining the coordinates of the head rotation center O (δx, δy) of the inkjet head 8 will be described with reference to FIG. FIG. 13 is a plan view illustrating the landing position before and after the θ rotation of the inkjet head 8 when the object to be coated is stopped. Since the printing object is stationary, there is no positional deviation due to movement, and only positional deviation due to the ejection angle from the droplet ejection nozzle. Therefore, the landing position before rotation is P _0V0 (Xa _V0 , Ya _V0 ), and the impact position after rotation by θ is P _θV0 (Xb _V0 , Yb _V0 ). Since P _θV0 corresponds to the position obtained by rotating P _0V0 by θ around point O, the relationship of the coordinates is expressed by equation (18 ), can be expressed by equation (19).

Then, when the coordinates (δx, δy) of point O are calculated from equations (18) and (19), they become as shown in equations (20) and (21).

The task of specifying the coordinates of the head rotation center point O only needs to be performed once at the beginning, when the inkjet head 8 is attached to the head rotation mechanism 10. It is not necessary to use all the nozzles for this operation, and it is preferable to select two droplet ejection nozzles separated from each other near both ends of the inkjet head 8 and select a nozzle with high ejection reproducibility.

As described above, according to the inkjet printing apparatus 40 according to the present embodiment, the target position of the droplet ejected from the inkjet head 8 when the inkjet head 8 is at the first and second rotation angles that are different from each other. Based on the landing position deviation characteristics calculated based on the landing position deviation from It becomes possible to print with

This method can be carried out by simultaneously applying droplets to the landing measurement area 1f and measuring the landing position deviation within 1f when printing the actual coating target area 1d. The landing position deviation is measured during production of a substrate 1 with a target part pitch W ₀ and a substrate 1 with a coating target part pitch W ₁ , and based on the measurement results, the landing position is determined for a substrate 1 with an arbitrary coating target part pitch. The head rotation angle of the inkjet head 8 can be set so that the deviation is minimized. As a result, according to the inkjet printing apparatus 40 according to the present embodiment, even in high-definition printing where it is necessary to take into account even landing position deviation due to the ejection angle of the droplet ejection nozzle, operation such as test printing, etc. High-precision printing is possible while minimizing processes that reduce printing efficiency.

As described above, according to the inkjet printing apparatus 40 according to the present embodiment, it is possible to measure the landing habit on a production board without using a special board for measuring the landing habit, and based on the result, it is possible to measure the landing habit on a production board. It is possible to accurately coat a substrate with an arbitrary coating target pitch without performing test printing. As a result, it is possible to print a high-definition display panel with a high operating rate.

The inkjet printing apparatus according to the above aspect of the present invention is effective for applying ink, etc. to a high-definition printing object at a constant pitch, and is effective for printing an organic EL light emitting body, a hole transport layer, or an electron transport layer. Alternatively, it can be applied to an inkjet printing device for printing color filters, etc.

1 Substrate (object to be coated)
1a Equipment 1b Alignment mark 1c Bank 1d Coating target area 1e Test printing area 1f Landing measurement area 1g Coating area 2 Substrate suction table 3 Substrate rotation mechanism 4 Substrate slider 5 Substrate guide rail 6 Linear motor for substrate transfer 7 Substrate transfer position detection Means 8 Inkjet head 9 Bracket 10 Head rotation mechanism 11 Bracket 12 Slider for head unit transfer 13 Guide rail for head unit transfer 14 Linear motor for head unit transfer 15 Position detection means for head unit transfer 16 Support part 17 Surface plate 18 Frame 21 Alignment camera 22 Head unit base 23 Inkjet head section 30 Substrate transport stage 32 Head unit 33 Head unit transfer stage 40 Inkjet printing device 100 Inkjet head control means 110 Storage means 120 Calculation means n ₁ First nozzle position n ₂ 2nd nozzle position n ₃ 3rd nozzle position n ₄ 4th nozzle position O Center of rotation of the inkjet head P ₁ Landing position shifted due to the ejection angle of the 1st nozzle P ₂ Ejection angle of the 2nd nozzle Landing position deviated due to the peculiarity of the ejection angle of the third nozzle P ₃ Landing position deviated due to the peculiarity of the ejection angle of the third nozzle P ₄ Landing position deviated due to the peculiarity of the ejection angle of the fourth nozzle Q ₁ Displacement of the ejection angle of the first nozzle The landing position shifted due to traveling Q ₂ The discharge angle of the second nozzle and the landing position shifted due to traveling Q ₃ The discharge angle of the third nozzle and the landing position shifted due to traveling Q 4 The discharge angle of the 3rd nozzle and the landing position shifted due to traveling Q ₄ Landing position shifted due to discharge angle and travel W ₀ coating area pitch W ₁ coating area pitch W ₂ coating area pitch

Claims (5)

An inkjet printing method in which ink is applied onto the object by ejecting droplets from the inkjet head while scanning the inkjet head relative to the object, the method comprising:
A memory that stores landing position deviation characteristics determined based on landing position deviations of droplets ejected from the inkjet head from a target position when the inkjet head is at first and second rotation angles that are different from each other. a first step of reading data related to the landing position deviation characteristics from the means;
A target rotation angle of the inkjet head is determined based on the landing position deviation characteristic, an arrangement pitch of droplet discharge nozzles of the inkjet head, and a target coating pitch of the coating object in a direction orthogonal to the scanning direction. and a second step of generating a printing pattern corresponding to the target rotation angle;
a third step of calculating an offset amount in a direction perpendicular to the scanning direction of the inkjet head to align the inkjet head with the coating target portion when the inkjet head is at the target rotation angle;
a fourth step of controlling the inkjet head based on the target rotation angle, the printing pattern, and the offset amount to eject droplets onto the coating target portion on the coating object;
An inkjet printing method comprising: The landing position deviation characteristics are determined by the following steps A to E and stored in the storage means,
A) positioning the inkjet head at the first rotation angle with the normal direction of the surface of the object to be coated as the rotation axis, and ejecting droplets in a first printing pattern;
B) detecting a landing position deviation of the droplet ejected in the step A) from the target position indicated by the first print pattern;
C) positioning the inkjet head at the second rotation angle and ejecting droplets in a second printing pattern;
D) detecting a displacement of the landing position of the droplet ejected in the step C) from the target position indicated by the second print pattern;
E) Calculating the landing position deviation characteristics based on the landing position deviation detected in step B), the landing position deviation detected in step D), and the coordinates of the rotation axis of the inkjet head. ,
The inkjet printing method according to claim 1 . In the fourth step, the relative movement speed between the inkjet head and the object to be coated is the same as the relative movement speed between the inkjet head and the object to be applied in the step A) and the inkjet in the step C). ejecting droplets from the inkjet head to the coating target portion under conditions that are the same as the relative movement speed between the head and the coating target;
The inkjet printing method according to claim 2 . An inkjet printing device that applies ink onto the object by discharging droplets from the inkjet head while scanning the inkjet head relative to the object, comprising:
A memory that stores landing position deviation characteristics determined based on landing position deviations of droplets ejected from the inkjet head from a target position when the inkjet head is at first and second rotation angles that are different from each other. means and
A target rotation angle of the inkjet head is determined based on the landing position deviation characteristic, an arrangement pitch of droplet discharge nozzles of the inkjet head, and a target coating pitch of the coating object in a direction orthogonal to the scanning direction. and a calculation means for generating a printing pattern corresponding to the target rotation angle;
a control means for controlling ejection timing for each droplet ejection nozzle of the inkjet head;
Equipped with
The calculating means calculates an offset amount in a direction perpendicular to a scanning direction of the inkjet head to align the inkjet head with the coating target portion when the inkjet head is at the target rotation angle,
The control means controls the inkjet head based on the target rotation angle, the printing pattern, and the offset amount to eject droplets onto a coating target portion on the coating object. a substrate suction table on which a substrate corresponding to the object to be coated is placed;
a substrate rotation mechanism that rotatably supports a lower portion of the substrate suction table;
a substrate transfer stage for transferring the substrate rotation mechanism and the substrate suction table;
a substrate transfer position detection means for detecting a substrate transfer position of the substrate transfer stage;
the inkjet head disposed above the substrate so as to face the substrate;
a head rotation mechanism disposed above the inkjet head and rotatably supporting the inkjet head about an axis normal to the plane of the substrate;
a head transfer stage that transfers the inkjet head and the head rotation mechanism in a direction perpendicular to a transfer direction and a rotation axis direction of the substrate transfer stage;
The inkjet printing device according to claim 4 , comprising:

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