CN113306292B

CN113306292B - Inkjet printing method and inkjet printing apparatus

Info

Publication number: CN113306292B
Application number: CN202110190787.2A
Authority: CN
Inventors: 井上隆史
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2020-02-26
Filing date: 2021-02-19
Publication date: 2024-07-30
Anticipated expiration: 2041-02-19
Also published as: JP7442128B2; TW202132124A; CN113306292A; JP2021133289A; KR20210108890A

Abstract

The invention provides an ink jet printing method for matching the landing pitch of liquid drops with the coating target pitch of a coating target part with high precision. The ink jet printing method includes a first step of reading data of landing position deviation characteristics from a storage unit (110) storing the landing position deviation characteristics, and the landing position deviation characteristics are solved based on landing position deviations from a target position of droplets ejected from an ink jet head (8) at a first rotation angle and a second rotation angle different from each other, respectively. And a second step of solving a target rotation angle of the inkjet head (8) based on the landing position deviation characteristic, the arrangement pitch of the droplet discharge nozzles of the inkjet head (8), and the coating target pitch of the coating object (1) in a direction orthogonal to the scanning direction, and generating a print pattern corresponding to the target rotation angle.

Description

Inkjet printing method and inkjet printing apparatus

Technical Field

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

Background

In recent years, a method of manufacturing a device using an inkjet printing apparatus has been attracting attention. An inkjet printing apparatus includes a plurality of nozzles that eject liquid droplets, and ejects liquid droplets from the nozzles while controlling a positional relationship between the nozzles and a target portion to be coated of a print target. Thus, the inkjet printing apparatus applies the droplets to the application target portion of the print target. As a print target, there is a print target in which coating target portions of the print target are arranged at a constant pitch, typified by a display device.

In the inkjet printing apparatus, an inkjet head is rotated about a rotation axis in a normal direction of a print target object plane, and a plurality of nozzles are arranged at a constant pitch. Thus, for example, japanese patent application laid-open No. 2001-108820 (hereinafter referred to as "patent document 1") discloses a method of coating such that the pitch of landing droplets matches the pitch of coating target portions of a coating object.

The conventional method disclosed in patent document 1 will be described with reference to fig. 14A, 14B and 15. Fig. 14A and 14B are diagrams showing the positional relationship between the pitch of the application target portions and the droplet discharge nozzles of the inkjet head. Fig. 15 is a diagram showing an operation flow of adjusting the pitch of a conventional coating target portion and the landing pitch of a droplet ejected from an inkjet head and landing on a substrate.

Fig. 14A and 14B illustrate the inkjet head 108, the droplet ejection nozzle 117 of the inkjet head 108, the substrate 119, the coating target portion 101 on the substrate 119, the droplet 118 landed on the coating target portion 101, and the like.

Fig. 14A shows a case where the coating target pitch W ₁ of the coating target portion 101 is equal to the pitch L of the droplet discharge nozzles 117. On the other hand, fig. 14B shows a case where the coating target pitch W ₂ of the coating target portion 101 is smaller than the pitch L of the droplet discharge nozzles 117.

As shown in fig. 14A and 14B, the inkjet head 108 and the substrate 119 are configured to eject droplets from the droplet ejection nozzle 117 and apply the droplets to the application target portion 101 while relatively moving in the X direction shown in the drawing. At this time, when the coating target pitch W ₂ of the coating target portion 101 is smaller than the pitch L of the droplet discharge nozzles 117, as shown in fig. 14B, the inkjet head 108 is rotated by the angle θ so that the pitch in the Y direction of the droplet discharge nozzles 117 matches the coating target pitch W ₂ of the coating target portion 101.

In the above-described conventional method, an operation of matching the Y-directional pitch of the droplets 118 ejected from the droplet ejection nozzles 117 and landed on the substrate 119 with the pitch of the coating target portion 101 of the substrate 119 will be described with reference to fig. 15.

As shown in fig. 15, the above-described operation includes ten steps from step S1 to step S10.

Specifically, the "pattern for drawing adjustment" in step S1 is a step of applying a test pattern for measuring the droplet pitch, and the "pattern after drawing by the sensor input" in step S2 is a step of introducing the test pattern by a camera or the like. The "dot division processing" in step S3 is a step of performing a process of dividing a droplet portion from the data introduced in step S2, and the "dot gravity center calculation processing" in step S4 is a step of calculating the gravity center of a droplet from the droplet data extracted in step S3. The "R pitch calculation, G pitch calculation, and B pitch calculation" in step S5 are steps for calculating the landing pitch of each landing droplet of R, G, B based on the gravity center position of each landing droplet of R, G, B calculated in step S4. The "inter-RG pitch calculation and inter-GB pitch calculation" in step S6 are steps for calculating the landing pitch between RG and the landing pitch between GB based on the center of gravity positions of each of the R landing droplet, G landing droplet, and B landing droplet extracted in step S4. Is the "RGB pitch of step S7 a predetermined distance? "is a step of determining whether or not the landing pitch of each landing droplet of R, G, B calculated in step S5 has reached the target distance. Is the "inter-RG pitch and inter-GB pitch of step S8 a predetermined distance? "is a step of determining whether or not the inter-RG landing distance and the inter-GB landing distance calculated in step S6 are the target distances. The "adjustment of the Y axis of the drawing head" in step S9 is a step of moving the drawing head in the Y direction to adjust the position when the landing pitch between RG and GB does not reach the target distance in step S8. In step S7, the "adjustment of the θ axis of the drawing head" in step S10 is a step of adjusting the θ rotation of the drawing head when the landing pitches of RGB do not reach the target distance.

That is, in the conventional method, the test pattern is printed in step S1, and the landing positions of the droplets of the test pattern are detected in steps S2 to S4. Further, the landing pitches of R, G, B are calculated in step S5, and in step S7, it is determined whether or not the landing pitches match the target values. When the landing pitch does not match the target value, the θ rotation adjustment of the drawing head is performed in step S10, and then the test printing in step S1 is performed again. After R, G, B the landing pitches match the target value, it is further determined in step S8 whether or not the landing pitches between RG and GB calculated in step S6 match the target value. When the landing pitches between RG and GB do not match the target values, Y-axis adjustment is performed in step S9, and then the test printing in step S1 is performed again.

As described above, in the conventional method, test printing is performed every time the pitch of the coating target portion is changed, and the landing pitch of the droplets is measured. Further, the rotation angle is finely adjusted based on the measurement result, and the approximation of the rotation angle and the approximation in the Y direction need to be repeatedly performed until the target threshold value is reached. In the case of this method, when the fineness is low and the target threshold is large, adjustment can be performed by the above-described approximation processing 1 to 2 times, and thus there is substantially no problem.

However, in recent years, in the course of increasing demands for high definition of display devices, it is demanded to reduce the pitch of the coating target portions. Therefore, it is necessary to precisely align the landing pitch of the liquid droplets ejected from the nozzles. When coating a high-definition display device, a fine landing position deviation of the droplet discharged from each nozzle due to the inherent discharge angle and a landing position deviation caused by relative movement between the object to be coated and the inkjet head have a large influence on the accuracy of the coating position.

Therefore, in the conventional method, when coating a high-definition display device, it is necessary to stop a normal printing operation and repeatedly perform a plurality of operations for approaching the landing pitch every time the pitch of the coating target portion changes. As a result, the operation rate of the inkjet printing apparatus is reduced. In addition, in order to approach the landing pitch, a dedicated substrate for test needs to be prepared, or a wide test print area needs to be provided on the production substrate.

Disclosure of Invention

The present invention provides an inkjet printing method capable of determining an optimal head rotation amount even if the pitch of a coating target portion of a coating object is changed, so as to match the landing pitch of liquid drops with the pitch precision of the coating target portion well, and an inkjet printing device using the inkjet printing method.

In one embodiment of the present invention, an inkjet printing method is provided in which an inkjet head is scanned relative to an object to be coated, droplets are ejected from the inkjet head, and ink is applied to the object to be coated. The inkjet printing method includes a first step of reading data on landing position deviation characteristics from a storage section storing the landing position deviation characteristics, the landing position deviation characteristics being solved based on landing position deviations from a target position of droplets ejected from an inkjet head at first and second rotation angles different from each other, respectively. Further, the method includes a second step of solving a target rotation angle of the inkjet head based on the landing position deviation characteristic, an arrangement pitch of the droplet discharge nozzles of the inkjet head, and a coating target pitch of the coating object in a direction orthogonal to the scanning direction, and generating a print pattern corresponding to the target rotation angle. And a third step of controlling the inkjet head based on the target rotation angle and the print pattern so that the droplets are ejected to the coating target portion on the coating object.

Another aspect of the present invention is an inkjet printing apparatus that causes an inkjet head to scan an object to be coated, while causing droplets to be ejected from the inkjet head, and applies ink to the object to be coated. The ink jet printing apparatus includes a storage unit that stores landing position deviation characteristics, which are calculated based on landing position deviations from a target position of droplets ejected from an ink jet head at first and second rotation angles different from each other, respectively. Further, the inkjet head device includes a calculation unit that calculates a target rotation angle of the inkjet head based on the landing position deviation characteristic, an arrangement pitch of liquid droplet ejection nozzles of the inkjet head, and a coating target pitch of the coating target in a direction orthogonal to the scanning direction, and generates a print pattern corresponding to the target rotation angle. The inkjet printing apparatus is configured to control the inkjet head based on the target rotation angle and the print pattern, and thereby to eject the liquid droplets onto the coating target portion on the coating target object.

According to the above aspect of the present invention, it is possible to provide an inkjet printing method capable of matching the landing pitch of droplets ejected from an inkjet head with the pitch of a coating target portion even if the pitch of the coating target portion of a coating target object changes, and an inkjet printing apparatus using the inkjet printing method.

Drawings

Fig. 1 is a perspective view of an inkjet printing apparatus according to an example of an embodiment.

Fig. 2 is a plan view of a substrate of an object to be coated according to an example of the embodiment.

Fig. 3A is a plan view illustrating landing position deviation of a droplet ejected from an inkjet head due to an inherent ejection angle.

Fig. 3B is a side view illustrating landing position deviation of a droplet ejected from an inkjet head due to an inherent ejection angle.

Fig. 4A is a plan view illustrating landing position deviation of droplets due to an inherent ejection angle when the rotation angle of the inkjet head is 0 degrees.

Fig. 4B is a plan view illustrating landing position deviation of a droplet due to an inherent ejection angle when the rotation angle of the inkjet head is Φ degrees.

Fig. 5A is a plan view illustrating landing positions of liquid droplets ejected from the inkjet head in a case where an object to be coated is stopped.

Fig. 5B is a side view illustrating landing positions of liquid droplets ejected from the inkjet head in a case where the object to be coated is stopped.

Fig. 6A is a plan view illustrating landing positions of droplets ejected from the inkjet head in a case where the coating object is traveling.

Fig. 6B is a side view illustrating landing positions of liquid droplets ejected from the inkjet head in a case where the coating object is traveling.

Fig. 7 is a plan view illustrating landing positions of droplets ejected when the rotation angle of the inkjet head is 0 degrees in the case where the object to be coated is traveling.

Fig. 8A is a plan view illustrating the amount of Y-direction positional deviation between the landing position of the droplet ejected when the rotation angle of the inkjet head is 0 degrees and the coating target portion of the coating object in the case where the coating object is traveling.

Fig. 8B is a plan view illustrating an X-direction distance between a landing position of a droplet ejected when the rotation angle of the inkjet head is 0 degrees and the Y-axis in the case where the object to be coated is traveling.

Fig. 8C is a plan view illustrating a landing position in the case where the landing position when the rotation angle of the inkjet head is 0 degrees is on the Y axis, with the ejection timing corrected in the case where the coating object is traveling.

Fig. 8D is a plan view illustrating landing positions of droplets in the case where printing is performed on a coating object in a state where the landing positions are on the Y axis when the ejection timing is corrected so that the rotation angle of the inkjet head is 0 degrees.

Fig. 8E is an enlarged view of a portion a of fig. 8D.

Fig. 9A is a plan view illustrating the amount of Y-direction positional deviation between the landing position of the droplet ejected when the rotation angle of the inkjet head is θ degrees and the coating target portion of the coating object in the case where the coating object is traveling.

Fig. 9B is a plan view illustrating an X-direction distance between a landing position of a droplet ejected when the rotation angle of the inkjet head is θ degrees and the Y axis in the case where the object to be coated is traveling.

Fig. 9C is a plan view illustrating a landing position in the case where the landing position when the rotation angle of the inkjet head is θ degrees is on the Y axis, with the ejection timing corrected in the case where the coating object is traveling.

Fig. 9D is a plan view illustrating landing positions of droplets in the case where printing is performed on a coating object in a state where the landing positions are on the Y axis when the ejection timing is corrected so that the rotation angle of the inkjet head is θ degrees.

Fig. 9E is an enlarged view of a portion a of fig. 9D.

Fig. 10A is a plan view illustrating the amount of Y-direction positional deviation between the landing position of the droplet ejected when the rotation angle of the inkjet head is Φ degrees and the coating target portion of the coating object in the case where the coating object is traveling.

Fig. 10B is a plan view illustrating the distance in the X direction between the landing position of the droplet ejected and the Y axis when the rotation angle of the inkjet head is Φc degrees in the case where the object to be coated travels.

Fig. 10C is a plan view illustrating a landing position in the case where the ejection timing is corrected so that the landing position when the rotation angle of the inkjet head is Φc degrees is on the Y axis when the coating object travels.

Fig. 10D is a plan view illustrating landing positions of droplets in the case where the ejection timing is corrected so that the landing positions are on the Y axis when the coating object is coated when the rotation angle of the inkjet head is Φc degrees.

Fig. 10E is an enlarged view of a portion a of fig. 10D.

Fig. 11 is a plan view illustrating landing positions of the inkjet head before and after the rotation of θ degrees in the case where the object to be coated is being scanned at the speed V.

Fig. 12 is a plan view illustrating a landing position when the inkjet head is rotated by Φ degrees in the case where the object to be coated is being scanned at the speed V.

Fig. 13 is a plan view illustrating landing positions of the inkjet head before and after rotation by θ degrees in the case where the object to be coated is stopped.

Fig. 14A is a diagram illustrating a case where the ink jet head is adjusted to match the pitch of the coating target portion of the coating object in the conventional example.

Fig. 14B is a diagram illustrating a case where the ink jet head is adjusted to match the pitch of the coating target portion of the coating object in the conventional example.

Fig. 15 is a flowchart for adjusting the pitch of the coating target portion of the coating object and the pitch of the droplets ejected from the inkjet head in the conventional example.

Detailed Description

(Embodiment)

Hereinafter, the inkjet printing apparatus 40 according to the present embodiment will be described in detail with reference to the drawings.

(Structure of ink jet printing apparatus)

First, the overall configuration of an inkjet printing apparatus 40 according to an example of the present embodiment will be described with reference to fig. 1.

Fig. 1 is a perspective view of an inkjet printing apparatus 40 according to an example of the present embodiment.

As shown in fig. 1, the inkjet printing apparatus 40 according to the present embodiment includes at least: a stand 18 for supporting the device; a platform 17 provided on a stand 18; a substrate transfer table 30; a head unit 32; the head unit displacing table 33; two support portions 16, and the like. The substrate transfer table 30 transfers the substrate set on the stage 17 in the X direction. The head unit displacement stage 33 conveys the head unit 32 in the Y direction orthogonal to the substrate conveyance stage 30. Two support portions 16 support both ends of the head unit displacement table 33 on the platform 17.

The substrate transport table 30 is composed of a substrate guide 5, a substrate transport slide 4 guided by the substrate guide 5 and supported so as to be slidable in the X direction, a substrate rotation mechanism 3 provided on the substrate transport slide 4, a substrate suction table 2 provided above the substrate rotation mechanism 3, and the like. The substrate transport slide 4 is feedback-controlled by a linear motor 6 for substrate transport, a substrate transport position detecting unit 7, and a substrate transport table control unit, not shown.

The substrate rotation mechanism 3 includes a substrate rotation angle detection unit and a substrate rotation driving unit, which are not shown. The substrate rotation mechanism 3 is configured to be precisely positioned at a target rotation angle by a substrate rotation mechanism control unit, not shown.

On the other hand, the head unit displacement table 33 is constituted by a head unit displacement guide 13, a head unit displacement slider 12, and the like, and the head unit displacement slider 12 is guided by the head unit displacement guide 13 and supported slidably in the Y direction. The head unit displacement slider 12 is feedback-controlled by means of a head unit displacement linear motor 14, a head unit displacement position detecting section 15, and a head unit displacement table control section, not shown.

The head unit 32 is configured by mounting the inkjet head 23 and the alignment camera 21 on the head unit base 22, and the head unit base 22 is attached to the head unit displacement slider 12. The inkjet head 23 includes: a head rotation mechanism 10 mounted on a head unit base 22 via a bracket 11; and an inkjet head 8 mounted below the head rotation mechanism 10 via a head holder 9. The head rotation mechanism 10 includes a head rotation angle detection unit, not shown, and a head rotation driving unit. The head rotation mechanism 10 is configured to be capable of being precisely positioned at a target rotation angle by a head rotation mechanism control unit, not shown.

The inkjet head 8 has a plurality of droplet discharge nozzles. The inkjet head 8 is configured so that the inkjet head control unit 100 can control the ejection timing for each droplet ejection nozzle of the inkjet head 8 based on the detection position obtained by the substrate transport position detection unit 7. The plurality of droplet discharge nozzles of the inkjet head 8 are arranged in a row at a predetermined pitch, for example.

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

The inkjet head control unit 100 includes a storage unit 110, a calculation unit 120, and the like. The storage unit 110 stores landing position deviation characteristics of the liquid droplets when the liquid droplets are ejected from the inkjet head 8. The calculation unit 120 obtains a target rotation angle of the inkjet head 8 based on the landing position deviation characteristic, the arrangement pitch of the droplet discharge nozzles of the inkjet head 8, and the coating target pitch of the coating object in the direction orthogonal to the scanning direction, and generates a print pattern corresponding to the target rotation angle. The landing position deviation characteristic is calculated based on landing position deviations from the target position of the liquid droplets ejected from the inkjet head 8 at the first rotation angle and the second rotation angle different from each other, respectively, of the inkjet head 8. Details are described later.

In the substrate transfer stage 30 and the head unit displacement stage 33 of the present embodiment, an air bearing mechanism is used. Thus, highly accurate positioning can be achieved.

(Action of inkjet printing device)

Next, the operation of the inkjet printing apparatus 40 having the above-described configuration will be described with reference to fig. 2 to 13.

Fig. 2 is a plan view of a substrate 1 of an object to be coated, which is an example of the present embodiment.

As shown in fig. 2, the substrate 1 has: a fixture 1a; and an alignment mark 1b, a bank 1c, a coating target portion 1d, a test print area 1e, and the like formed on the fixture 1 a. The alignment marks 1b are formed at four corners on the fixture 1 a. The bank 1c functions as a bank to prevent the ink printed on the coating target portion 1d from overflowing. The coating target portions 1d are surrounded by the banks 1c and arranged at a constant pitch. The test printing area 1e has a landing measurement area 1f, and is provided for measuring landing positions of liquid droplets.

The landing measurement region 1f is formed in the test print region 1 e. The landing measurement regions 1f are formed on the extension line of the coating target portion 1d at the same pitch as the coating target portion 1 d.

The coating target portion 1d is a region of the display panel constituting a pixel. The coating target portion 1d is configured such that the landed liquid droplet wets and spreads. On the other hand, the landing measurement region 1f is configured to have liquid repellency. Thereby, the droplet landed on the landing measurement region 1f is held in a circular shape. Therefore, by capturing the positions of the landed droplets with the alignment camera 21 and processing the captured droplets with an image processing unit, not shown, the positions of the centers of circles with respect to the landing measurement region 1f can be accurately measured.

The substrate 1 further includes a coating region 1g. The coating region 1g is composed of a region having liquid repellency similarly to the landing measurement region 1 f. The coating region 1g is provided as a region for measuring the approximate landing position of the droplet when the droplet does not enter the circle of the landing measurement region 1 f.

(When the substrate 1 and the inkjet head 8 are not relatively moved)

Next, a relationship between the position of the droplet discharge nozzle of the inkjet head 8 and the landing position of the droplet discharged from the droplet discharge nozzle on the substrate 1 when the substrate 1 and the inkjet head 8 are not relatively moved will be described with reference to fig. 3A to 4B.

Fig. 3A is a plan view illustrating landing position deviation of liquid droplets ejected from the inkjet head 8 due to an inherent ejection angle. Fig. 3B is a side view of fig. 3A.

Fig. 4A is a plan view illustrating landing position deviation of liquid droplets due to an inherent ejection angle when the rotation angle of the inkjet head 8 is 0 (zero) degrees. Fig. 4B is a plan view illustrating landing position deviation of a droplet due to an inherent ejection angle when the rotation angle of the inkjet head is Φ degrees.

Here, the inkjet head 8 shown in fig. 3A is represented by a dotted circle, and has four droplet ejection nozzles. The hole position of the droplet discharge nozzle is set to n ₁、n₂、n₃、n₄. In general, each droplet discharge nozzle has different properties (corresponding to the above-described inherent discharge angle) in the discharge direction due to the processing accuracy during manufacturing or the like. Therefore, as shown in fig. 3B, the landing position at the time of landing on the surface of the substrate 1 separated from the droplet discharge nozzle surface of the inkjet head 8 by the distance G becomes a landing position P ₁、P₂、P₃、P₄ indicated by a solid line circle. That is, the landing position P ₁、P₂、P₃、P₄ reaches a position different from that just below the hole position n ₁、n₂、n₃、n₄ of the droplet ejection nozzle. Hereinafter, the amount of positional deviation will be referred to as "landing positional deviation" due to the inherent ejection angle.

The landing position deviation of each droplet discharge nozzle due to the inherent discharge angle is determined by the shape accuracy of the hole of the droplet discharge nozzle, the surface state of the periphery of the droplet discharge nozzle, and the like. That is, the inherent ejection angle from the droplet ejection nozzle becomes a fixed attribute in the assembled inkjet head 8. Therefore, when the inkjet head 8 shown in fig. 4B is rotated with the rotation angle being Φ degrees, the landing position P ₁、P₂、P₃、P₄ is also deviated in the same direction in the inkjet head 8 from the hole position n ₁、n₂、n₃、n₄ of the droplet discharge nozzle of the inkjet head, as compared with the case where the rotation angle of the inkjet head 8 shown in fig. 4A is 0 degrees. That is, fig. 4B, which is a top view of the inkjet head 8 rotated by Φ degrees, is a position obtained by directly rotating fig. 4A by Φ degrees. The rotation center O indicated by a black circle in fig. 4A and 4B corresponds to the rotation axis of the inkjet head 8.

(Case where the substrate 1 and the inkjet head 8 are relatively moved)

Next, with reference to fig. 5A to 6B, a landing position in a case where droplets are ejected from the droplet ejection nozzles of the inkjet head 8 toward the substrate 1 while the substrate 1 is traveling at a constant velocity V with respect to the inkjet head 8 will be described.

Fig. 5A is a plan view illustrating landing position deviation of liquid droplets ejected from the inkjet head 8 in the case where the object to be coated is stopped. Fig. 5B is a side view of fig. 5A. Fig. 6A is a plan view illustrating landing position deviation of liquid droplets ejected from the inkjet head in the case where the object to be coated is traveling at a speed V. Fig. 6B is a side view of fig. 6A.

As shown in fig. 5A, in a state where the substrate 1 is stopped, a landing position where the droplet ejected from the droplet ejection nozzle of the hole n ₁ of the inkjet head 8 lands on the substrate 1 is set to P ₁. The amount of positional deviation of the landing position P ₁ with respect to the hole position n ₁ corresponds to the landing position deviation due to the inherent ejection angle described in fig. 4A and 4B. In contrast, the droplet holding speed discharged from the droplet discharge nozzle of the hole n ₁ flies toward the substrate 1 traveling at the constant speed V. Therefore, time is required before the droplet reaches the substrate 1. If this time is set to Δt, during this period, the substrate 1 advances by an amount of Δt×v. Therefore, as shown in fig. 6A, the landing position Q ₁ of the droplet on the substrate 1 is deviated from the landing position P ₁ when landing on the substrate 1 in the stationary state.

In practice, the droplets flow under the influence of the wind generated by the travel of the substrate 1 under the influence of the deceleration due to the resistance of the air during the flight toward the substrate 1, and thus become more complicated positional deviations. Hereinafter, the landing position deviation Δx _1v in the traveling direction due to the traveling of the substrate 1 is referred to as "landing position deviation" due to the traveling. That is, the above-described landing position deviation due to traveling is a landing position deviation accompanying traveling of the substrate 1, and is therefore basically a position deviation generated in the traveling direction. Therefore, unlike the positional deviation due to the inherent ejection angle of the inkjet head 8, the positional deviation does not rotate together with the rotation of the inkjet head 8 even when the inkjet head 8 is rotated.

As described above, when the substrate 1 is stopped, the landing position of the droplet discharged from the hole position n ₁ of the droplet discharge nozzle on the substrate 1 is the landing position P ₁ having only the landing position deviation due to the inherent discharge angle. On the other hand, when the substrate 1 is traveling at the speed V, the landing position P ₁ is a position where the landing position deviation is added to the landing position deviation Δx1v due to the traveling of the substrate 1 in the traveling direction, which is caused by the inherent ejection angle.

Next, a method of printing droplets on the coating target portion 1d of the substrate 1 will be described below in 1) and 2).

1) First, an alignment method of the substrate 1 is described.

First, the substrate 1 is suction-fixed on the substrate suction stage 2, and the substrate conveying stage 30 and the head unit displacing stage 33 are moved.

Next, the alignment marks 1b at the four corners of the substrate 1 are moved downward of the alignment camera 21 mounted on the head unit 32.

Next, the alignment mark 1b is photographed by the alignment camera 21, and the position of the alignment mark 1b is measured by an image recognition unit, not shown. On the other hand, based on the detection position obtained by the substrate transport position detection section 7 and the detection position obtained by the head unit displacement position detection section 15 at this time, the substrate rotation mechanism 3 is driven and adjusted by a control section, not shown, so that the traveling direction of the substrate transport table 30 is parallel to the direction of the coating target section 1d of the substrate 1.

2) Next, a method of adjusting the positions of the droplet discharge nozzle and the coating target portion 1d of the substrate 1 will be described with reference to fig. 7.

Fig. 7 is a plan view illustrating landing positions of droplets ejected by the inkjet head at a first rotation angle (here, the rotation angle is 0 (zero) degrees) in the case where the object to be coated travels at a speed V.

In fig. 7, a circle of a broken line in the drawing indicates a hole position n ₁、n₂、n₃、n₄ of a droplet discharge nozzle in the inkjet head 8. The solid line circle indicates the landing position P ₁、P₂、P₃、P₄ where the liquid droplet ejected from the liquid droplet ejection nozzle reaches the substrate 1 due to the inherent ejection angle and the positional deviation occurs. In addition, a circle of a double solid line in fig. 7 represents a landing position Q ₁、Q₂、Q₃、Q₄ obtained by adding a landing position deviation due to traveling to the landing position P ₁、P₂、P₃、P₄ and the landing position deviation due to traveling of the substrate 1.

In fig. 7, the rotation axis of the inkjet head 8 is positioned at a rotation angle of 0 degrees around the rotation center O indicated by a black circle so that the droplet pitch in the Y direction of the inkjet head 8 coincides with the coating target pitch W ₀ of the coating target portion 1 d.

(Calculation of landing position deviation characteristics)

Next, a method of calculating a characteristic of landing position deviation (hereinafter, simply referred to as "landing position deviation characteristic") of the inkjet printing apparatus 40 generated when ejecting liquid droplets from the inkjet head 8 will be described with reference to fig. 8A to 8E.

Fig. 8A is 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 1d of the coating object in the state of fig. 7, that is, in the case where the coating object is traveling at the speed V, when the rotation angle of the inkjet head is 0 degrees.

In fig. 8A, the distance in the Y direction between the position in the Y direction of the landing position Q ₁、Q₂、Q₃、Q₄ of the droplet and the central axis of the coating target portion 1d is represented by Δy ₁₀、ΔY₂₀、ΔY₃₀、ΔY₄₀.

That is, the alignment in the Y direction between the inkjet head 8 and the substrate 1 is performed so that the total error of Δy ₁₀、ΔY₂₀、ΔY₃₀、ΔY₄₀ is minimized.

Fig. 8B is a plan view illustrating the distance in the X direction between the landing position of the ejected droplet and the Y axis when the rotation angle of the inkjet head 8 is 0 degrees in the state of fig. 7, that is, when the object to be coated travels at the speed V.

In fig. 8B, X _1S0、X_2S0、X_3S0、X_4S0 represents the distance in the X direction between the landing position Q ₁、Q₂、Q₃、Q₄ of the droplet and the Y axis.

Fig. 8C shows landing positions where ejection timings corresponding to the distance X _1S0、X_2S0、X_3S0、X_4S0 in the X direction are corrected. That is, by correcting the ejection timing, as shown in fig. 8C, it is possible to eject droplets from all the droplet ejection nozzles, and print the droplets so that the landing positions of the droplets on the substrate 1 are aligned substantially on the Y axis (including the Y axis). Hereinafter, this print pattern is referred to as a "first print pattern".

Fig. 8D shows landing positions of droplets in the case where the landing measurement region 1f and the coating target portion 1D of the substrate 1 are printed in the above-described state. Hereinafter, this printing is referred to as "first printing step". Here, in fig. 8D, the liquid droplets in the coating target portion 1D are represented by double circles. However, in reality, the coating target portion 1d has hydrophilicity. Therefore, the droplet landed on the coating target portion 1d wets and spreads in the coating target portion 1 d. On the other hand, the landing measurement region 1f has liquid repellency. Therefore, the droplet landed on the landing measurement region 1f has a circular shape among circles surrounding the landing measurement region 1f as shown in fig. 8D.

Fig. 8E is an enlarged view of a portion a in fig. 8D, which is shown together with the plan view of fig. 8D.

In the above state, the landing measurement region 1f of fig. 8E is photographed by the alignment camera 21 and subjected to image processing. Then, the positional deviation Δy _i0 in the Y direction and the positional deviation Δx _i0 in the X direction between the circle of the landing measurement region 1f of the coating target pitch W ₀ and the circle of the droplet in the landing measurement region 1f are detected (i=1, 2,3, 4). This enables accurate measurement of the landing position deviation of the droplet. Hereinafter, this measurement is referred to as a "first landing position deviation detection step".

As a result, the landing position in the case where the correction of the ejection timing is not performed can be accurately calculated from the measurement results Δx _i0 and Δy _i0 of the landing position deviation of the liquid droplet in the landing measurement region 1f and the correction amount X _iS0 converted by the correction of the ejection timing in fig. 8C. Hereinafter, this calculation step is referred to as a "first landing position calculation step". The calculated landing position data is referred to as "first landing position data".

Next, a case will be described with reference to fig. 9A to 9E in which, when the coating target pitch of the coating target portion 1d is W ₁ smaller than W ₀, the inkjet head 8 is rotated by θ degrees about the rotation axis, that is, the rotation center O so that the droplet pitch matches W ₁, and coating is performed.

Fig. 9A is a plan view illustrating the amount of positional deviation in the Y direction between the landing position of the droplet ejected by the inkjet head 8 at the second rotation angle (here, the rotation angle is θ degrees) and the coating target portion 1d of the coating object in the case where the coating object travels at the speed V. In fig. 9A, the Y-direction distance between the Y-direction position of the landing position Q ₁、Q₂、Q₃、Q₄ of the droplet and the central axis of the coating target portion 1d is denoted by Δy _1θ、ΔY_2θ、ΔY_3θ、ΔY_4θ.

Further, the alignment in the Y direction between the inkjet head 8 and the substrate 1 is performed so that the total error of Δy _1θ、ΔY_2θ、ΔY_3θ、ΔY_4θ is minimized.

Fig. 9B is a plan view illustrating the distance in the X direction between the landing position of the droplet ejected and the Y axis in the state of fig. 9A, that is, when the rotation angle of the inkjet head 8 is θ degrees in the case where the coating object travels at the speed V.

In fig. 9B, X _1Sθ、X_2Sθ、X_3Sθ、X_4Sθ represents the distance in the X direction between the landing position Q ₁、Q₂、Q₃、Q₄ of the droplet and the Y axis.

Fig. 9C shows landing positions of liquid droplets in the case where ejection timings corresponding to the X-direction distance X _1Sθ、X_2Sθ、X_3Sθ、X_4Sθ shown in fig. 9B are corrected. That is, as shown in fig. 9C, by adjusting the ejection timing, all landing positions of the droplets ejected from the droplet ejection nozzles and reaching the substrate 1 can be aligned substantially on the Y axis (including the Y axis). Hereinafter, this print pattern is referred to as a "second print pattern".

Fig. 9D shows landing positions of droplets in the case where the landing measurement region 1f and the coating target portion 1D of the substrate 1 are printed in the state of fig. 9C. Hereinafter, this printing is referred to as "second printing step". In fig. 9D, the liquid droplets in the coating target portion 1D are indicated by double circles. In reality, however, the coating target portion 1d has hydrophilicity. Thus, the droplets landing on the coating target portion 1d wet spread. On the other hand, the landing measurement region 1f has liquid repellency. Therefore, the droplet landed on the landing measurement region 1f has a circular shape among circles surrounding the landing measurement region 1f as shown in fig. 9D.

Fig. 9E is an enlarged view of a portion a in fig. 9D, which is shown together with the plan view of fig. 9D.

In the above state, the landing measurement region 1f of fig. 9E is photographed by the alignment camera 21 and subjected to image processing. Then, the positional deviation Δy _iθ in the Y direction and the positional deviation Δx _iθ in the X direction between the circle of the landing measurement region 1f of the coating target pitch W ₁ and the circle of the droplet in the landing measurement region 1f are detected (i=1, 2,3, 4). This enables accurate measurement of the landing position deviation of the droplet. Hereinafter, this measurement is referred to as a "second landing position deviation detection step".

As a result, the landing position in the case where the correction of the ejection timing is not performed can be accurately calculated from the measurement results Δx _iθ and Δy _iθ of the landing position deviation of the liquid droplet in the landing measurement region 1f and the correction amount X _iSθ converted by the correction of the ejection timing in fig. 9C. Hereinafter, this calculation step is referred to as a "second landing position calculation step". And, the calculated landing position data is taken as "second landing position data".

In the present embodiment, the relative movement speed between the inkjet head 8 and the substrate 1 in the first printing step and the relative movement speed between the inkjet head 8 and the substrate 1 in the second printing step are set to be the same.

As described above, the inkjet head 8 is rotated by θ degrees for the substrate with the coating target pitch W ₀ of the coating target portion 1d shown in fig. 8A and the substrate with the coating target pitch W ₁ of the coating target portion 1d shown in fig. 9A. This makes it possible to print the droplet application target pitch and the application target pitch of the application target portion in a matching manner.

At this time, the landing positions of the respective droplets are accurately measured for the coating target pitches of the different coating target portions 1 d.

Then, based on the measurement results of landing positions of the liquid droplets in the above two substrates 1, an optimum rotation angle of the inkjet head 8 that minimizes the landing deviation with respect to the substrate of any coating target pitch is calculated. Thus, the droplets can be applied at appropriate positions with respect to the substrate having any application target pitch without performing test printing.

The above method will be described below with reference to fig. 11.

Fig. 11 is a diagram showing the relationship of landing positions of droplets when the rotation angle of one nozzle in the inkjet head 8 about the head rotation center O is 0 (zero) degrees and when θ degrees are rotated from this point on. Here, the X coordinate of the head rotation center O is δx and the Y coordinate is δy. The landing position at 0 degree of rotation is Q ₀, the X coordinate of Q ₀ is Xa, the Y coordinate is Ya, and Q ₀ (Xa, ya) is described. 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, and the Y coordinate is Yb, and Q _θ (Xb, yb) is described. The positional deviation in the X direction of the landing position of the droplet due to the travel of the substrate 1 is defined as Δx _V.

That is, in the case of coating the traveling substrate 1, the landing position deviation of the droplet ejected from the inkjet head 8 and landed on the substrate 1 is a value obtained by adding the landing position deviation due to the traveling substrate 1 to the landing position deviation due to the inherent ejection angle when the droplet is ejected from the droplet ejection nozzle. At this time, as described above, the landing position deviation due to the inherent ejection angle rotates together with the rotation of the inkjet head 8. On the other hand, the landing position deviation due to the travel of the substrate 1 is determined by the travel direction of the substrate 1, independently of the rotation of the inkjet head 8. That is, landing positions P ₀、P_θ of the inkjet head 8 at the rotation angles of 0 degrees and θ degrees, respectively, caused only by the inherent ejection angle are: the X coordinate of P ₀ is Xa-DeltaX _V, and the Y coordinate is Ya; the X coordinate of P _θ is Xb-DeltaX _V, and the Y coordinate is Yb.

The landing position P _θ corresponds to a position obtained by rotating the landing position P ₀ by θ degrees about the rotation center O, which is the head rotation axis. Therefore, the relationship between the point of the landing position P _θ and the point of the landing position P ₀ can be expressed as the following expressions (1) and (2) according to the expression of the rotation coordinates.

Further, by the above-described equations (1) and (2), the positional deviation Δx _V between the Y coordinate δy of the rotation axis of the inkjet head 8 and the travel of the substrate 1 can be solved as in equations (3) and (4). The X-axis coordinate δx of the rotation axis of the inkjet head 8 is also measured. The measurement method will be described later.

As described above, the X coordinate δx of the head rotation center O of the inkjet head 8 is previously calculated. Then, in the printing mode while the substrate 1 is traveling at the speed V, landing positions Q ₀ (Xa, ya) (first landing position data) and Q _θ (Xb, yb) (second landing position data) at two angles, i.e., the head rotation angle of the inkjet head 8 is 0 degrees (first rotation angle) and θ degrees (second rotation angle), are measured. This can solve the landing position deviation Δx _V of the droplet due to the travel of the substrate 1. Further, if the landing position deviation Δx _V is solved, the landing position deviation due to the inherent ejection angle can be solved. Hereinafter, this calculation step is referred to as a "landing position deviation characteristic calculation step".

The data on the landing position deviation characteristic calculated by the above method is stored in the storage unit 110 as data indicating the characteristic inherent to the inkjet head 8 used.

In the droplet discharge operation for calculating the landing position deviation characteristic, for example, when printing is performed on the application target portion 1d, droplets are applied to the landing measurement region 1f together. Then, the landing position deviation of the droplet in the landing measurement region 1f can be measured.

(Action at the time of printing)

The calculation unit 120 of the inkjet printing device 40 calculates the target rotation angle of the inkjet head 8 when printing is performed, using the landing position deviation characteristic calculated by the above method. Further, the computing unit 120 generates a print pattern corresponding to the target rotation angle.

In the present embodiment, the rotation angle at which the positional deviation at the coating target portion 1d of the coating object is minimized when the liquid droplets are ejected from the liquid droplet ejection nozzles of the inkjet head 8 is set as the target rotation angle of the inkjet head 8 at the time of printing.

Hereinafter, this target rotation angle may be referred to as "optimum rotation angle". In this case, the target rotation angle is preferably set to a rotation angle such that the positional deviation at the coating target portion 1d of the coating object is equal to or less than a threshold value when the liquid droplets are ejected from the liquid droplet ejection nozzles of the inkjet head 8.

A method of calculating the landing position of the inkjet head 8 at an arbitrary third rotation angle Φ while printing is performed while the substrate 1 is traveling at the speed V, based on the landing position deviation characteristic obtained as described above and the rotation center O (δx, δy) of the inkjet head 8, will be described below with reference to fig. 12. The landing position deviation characteristic includes landing position deviation Δx _V due to the travel of the substrate 1 and landing position deviation due to the inherent ejection angle.

Fig. 12 is a diagram illustrating landing position deviation of the liquid droplet when the head rotation angle of the inkjet head 8 is 0 degrees and phi degrees.

First, the arithmetic unit 120 reads data on the landing position deviation characteristic stored in the storage unit 110.

Next, the arithmetic unit 120 subtracts the landing position deviation Δx _V due to travel from the X coordinate of the landing position Q ₀ (Xa, ya) at the rotation angle of 0 degrees of the inkjet head 8. Then, the arithmetic unit 120 calculates landing positions P ₀(Xa-ΔX_V and Ya of the liquid droplets when there is only a deviation due to the inherent ejection angle.

Next, the arithmetic unit 120 calculates landing positions P _φ (Xd, yd) of the liquid droplets when there is only a deviation due to the inherent ejection angle, which is obtained by rotating the landing position P ₀ by Φ degrees around the rotation center O, which is the rotation center of the head. Then, the arithmetic unit 120 adds the landing position deviation Δx _V due to the travel of the substrate 1 to the X-coordinate of the calculated landing position P _φ point. Thus, the landing position Q _φ (Xe, ye) at the rotation angle Φ can be obtained. If the above is expressed by the expression, the coordinates of the point P _φ at the landing position can be expressed by the expressions (5) and (6), and the coordinates of the point Q _φ at the landing position can be expressed by the expressions (7) and (8). Hereinafter, a step of calculating the landing position at the third rotation angle Φ of the inkjet head 8 is referred to as a "landing position prediction step".

At this time, the computing unit 120 changes the third rotation angle Φ of the inkjet head 8 variously, and calculates landing positions of the droplets at the plurality of third rotation angles Φ.

Next, the calculating unit 120 calculates an optimum rotation angle Φc of the inkjet head 8 with respect to the coating target portion 1d of the coating object when the droplet is discharged from the inkjet head 8. Specifically, the calculating unit 120 calculates the optimum rotation angle Φc based on the arrangement pitch of the droplet discharge nozzles of the inkjet head 8 and the coating target pitch of the coating target portion 1d of the coating object in the direction orthogonal to the scanning direction. Specifically, the calculation unit 120 first calculates evaluation values regarding landing position deviations of the droplets with respect to the coating target portion 1d at a plurality of third rotation angles, that is, Φ degrees, of the inkjet head 8, for example. Then, the calculation unit 120 calculates the optimum rotation angle Φc based on the calculated evaluation value.

In the above equations (7) and (8), the calculation formulas of the landing position of one droplet discharge nozzle when the rotation angle of the inkjet head 8 is Φ degrees are shown.

In the following, a calculation formula of landing positions of the droplet discharge nozzles is shown for the case of the inkjet head 8 provided with a plurality of droplet discharge nozzles.

That is, the landing position coordinate of the ink jet head 8 of the i-th droplet ejection nozzle at the rotation angle of 0 degrees (first rotation angle) is (X _ia,Y_ia), the landing position coordinate of the ink jet head at the rotation angle of θ degrees (second rotation angle) is (X _ib,Y_ib), and the positional deviation amount of the i-th droplet ejection nozzle due to traveling is Δx _iv. When the landing position coordinate at the rotation angle Φ (third rotation angle) is (X _ie,Y_ie), the value of the landing position coordinate can be expressed as the following expressions (9) and (10).

Here, the positional deviation Δx _iv of the i-th nozzle due to traveling can be expressed by formula (11).

When the Y coordinate of the coating target portion 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, the difference Δy _i Φ between them can be expressed by formula (12).

Here, fig. 10A to 10E show the relationship between the difference Δy _iφ and the positional deviation Δx _iv. In fig. 10A to 10E, i denotes four droplet discharge nozzles 1,2,3, and 4.

Then, the calculating unit 120 calculates the square and average number Δt of the Y-direction positional deviations Δy _iφ of all the droplet discharge nozzles as an evaluation value in order to solve the optimum rotation angle Φc of the inkjet head 8, as shown in expression (13).

Next, the arithmetic unit 120 changes the rotation angle Φ, calculates the square and the average Δt when the rotation angle Φ is the same, and calculates the value of the rotation angle Φ such that the square and the average Δt are the smallest. The rotation angle phi at which the square and the average number Δt are minimized is set to the optimum rotation angle phic of the inkjet head 8.

DeltaY _iφ＝Y_ie--Yt_i -type (12)

The arithmetic unit 120 calculates the Y-direction offset amount Δy by using the expression (14). The offset amount Δy calculated by the offset when the substrate 1 and the inkjet head 8 are aligned is reflected in the printing.

The calculation unit 120 calculates the landing position coordinates X _ieφc in the X direction of each droplet discharge nozzle by using the expression (15) with respect to the X direction, and corrects the discharge timing by an amount corresponding to-X _ieφc. Hereinafter, the print pattern subjected to the ejection timing correction will be referred to as an "optimum print pattern". The generation step is referred to as an "optimal print pattern generation step".

When the rotation angle of the inkjet head 8 is set to the optimum rotation angle Φc, the landing position coordinate Y _ieφc in the Y direction of each droplet discharge nozzle is calculated by equation (16). Further, the position deviation Δy _ieφc in the Y direction from the target coordinates is calculated by expression (17). The Y coordinate of the landing position in consideration of the Y-direction shift is Y _ieφc - Δy.

DeltaY _iφc＝Y_ieφ_c-Yt_i -type (17)

That is, the inkjet head control unit 100 of the inkjet printing apparatus 40 positions the inkjet head 8 at the optimum rotation angle Φc and the offset Δy in the Y direction calculated by the above-described process, and performs printing in accordance with the above-described optimum print pattern. In this way, the inkjet printing device 40 can perform droplet ejection so as to minimize positional deviation with respect to the application target portion 1 d.

In the printing, the inkjet printing apparatus 40 controls the substrate transfer table 30 so that the relative movement speed between the inkjet head 8 and the substrate 1 is the same as the speed in the first printing step and the second printing step.

The above state is shown in fig. 10B to 10E.

Fig. 10B is a diagram showing the X-direction distance between the landing positions of the droplet ejection nozzles No.1, 2,3, and 4 and the Y-axis in the case where the optimum rotation angle Φc obtained by solving the head rotation angle of the inkjet head 8 is set as described above.

Fig. 10C is a diagram showing landing positions in the case where ejection timings by an amount corresponding to the X-direction distance between the landing positions of the droplet ejection nozzles and the Y-axis of fig. 10B are corrected. That is, as shown in fig. 10C, when the ejection timing is corrected by an amount corresponding to-X _ieφc which is the opposite direction of the amount calculated by the above formula (15), the landing positions of the droplet ejection nozzles overlap on the Y axis.

Fig. 10D shows a state in which the droplets are applied to the substrate 1.

By setting the rotation angle of the inkjet head 8 to the optimum rotation angle Φc as shown in fig. 10D, the positional deviation between the landing position of each droplet ejection nozzle and the coating target position is minimized.

Fig. 10E is an enlarged view of the landing position in the landing measurement region 1f at the time of actual coating, which is shown together with the plan view of fig. 10D. Fig. 10E shows landing positions in landing measurement areas of the liquid droplets discharged from the 3 rd and 4 th liquid droplet discharge nozzles. As can be seen from fig. 10E, the position deviation Δx _3φc、ΔX_4φc between the actually landed droplet and the target position in the X direction is substantially the target position.

When the positional deviation Δx _3φc、ΔX_4φc is to be further approximated, correction of the ejection timing corresponding to the positional deviation is performed. This can further reduce the positional deviation amount Δx _3φc、ΔX_4φc.

(Method for solving coordinates of center of rotation of inkjet head)

Next, a method for solving the coordinates of the rotation center O (δx, δy) of the inkjet head 8 will be described with reference to fig. 13.

Fig. 13 is a plan view illustrating landing positions of droplets of the inkjet head 8 before and after rotation by θ degrees when the object to be coated is stopped.

In this case, since the print target is stopped, there is no positional deviation due to traveling, and only positional deviation due to the inherent ejection angle from the droplet ejection nozzle is generated. That is, if the landing position before rotation is P _0V0(Xa_V0,Ya_V0) and the landing position after rotation by θ degrees is P _θV0(Xb_V0,Yb_V0), the landing position P _θV0 corresponds to a position obtained by rotating the landing position P _0V0 by θ degrees around the rotation center O. Accordingly, the relation of the coordinates can be expressed by the following formulas (18) and (19).

Then, if the coordinates (δx, δy) of the rotation center O of the inkjet head 8 are calculated based on the above equations (18) and (19), the equations (20) and (21) are obtained.

The operation of determining the coordinates of the rotation center O of the inkjet head 8 may be performed only once at the time of attaching the inkjet head 8 to the head rotation mechanism 10. It is preferable that the above-described operation is performed by selecting a nozzle having high discharge reproducibility, for example, using two droplet discharge nozzles located near and away from both ends of the inkjet head 8.

As described above, according to the inkjet printing apparatus 40 of the present embodiment, first, the landing position deviation characteristic is calculated based on the landing position deviation of the droplets ejected from the inkjet head 8 from the target position at the first rotation angle and the second rotation angle different from each other, respectively, of the inkjet head 8. Then, based on the calculated landing position deviation characteristic, the optimum head rotation amount of the inkjet head 8 can be set to print the coating target portion 1d of an arbitrary coating target pitch without performing test printing.

The above method can be implemented by: when printing is performed on the actual application target portion 1d, the droplets are applied to the landing measurement region 1f at the same time, and landing position deviation in the landing measurement region 1f is measured. Then, in the production of the substrate 1 coated with the target pitch W ₀ and the substrate 1 coated with the target pitch W ₁, the landing position deviation was measured. Then, based on the measurement result of the landing position deviation, the rotation angle of the droplet ejection head of the inkjet head 8 with respect to the substrate 1 of any coating target pitch is set so that the landing position deviation is minimized. As a result, according to the inkjet printing device 40 of the present embodiment, even in high-definition printing in which variations in landing positions due to the inherent discharge angle of the droplet discharge nozzles need to be taken into consideration, high-definition printing can be performed while minimizing the steps for reducing the operation rate, such as test printing.

As described above, according to the inkjet printing device 40 of the present embodiment, the landing property of the liquid droplets can be measured by using the actual production substrate without using a special substrate for measuring the landing property. Then, based on the measurement result, droplets can be accurately applied to the substrate without performing test printing on any substrate to which the target pitch is applied. As a result, the operation rate can be improved, and printing of a high-definition display panel can be performed.

Claims

1. An ink jet printing method of relatively scanning an object to be coated by an ink jet head, ejecting droplets from the ink jet head, and applying ink to the object to be coated,

The inkjet printing method includes:

A first step of reading, from a storage unit storing landing position deviation characteristics, data relating to the landing position deviation characteristics, the landing position deviation characteristics being obtained based on landing position deviations from a target position of droplets ejected from the inkjet head at first and second rotation angles different from each other, respectively;

A second step of solving a target rotation angle of the inkjet head based on the landing position deviation characteristic, an arrangement pitch of liquid droplet ejection nozzles of the inkjet head, and a coating target pitch of the coating object in a direction orthogonal to a scanning direction, and generating a print pattern corresponding to the target rotation angle; and

And a third step of controlling the inkjet head based on the target rotation angle and the print pattern so as to eject droplets onto a coating target portion on the coating object.

2. The method of inkjet printing according to claim 1 wherein,

The landing position deviation characteristic includes:

landing position deviation amount due to an inherent ejection angle of a droplet ejection nozzle of the inkjet head; and

Landing position deviation amount associated with scanning of the inkjet head.

3. The inkjet printing method according to claim 1 or 2 wherein,

The inkjet printing method further includes, between the second step and the third step, the steps of: calculating an offset amount of the inkjet head in a direction orthogonal to a scanning direction for aligning the inkjet head with the coating target portion when the inkjet head is at the target rotation angle,

In the third step, the inkjet head is controlled based on the target rotation angle, the print pattern, and the offset amount, so that the droplets are ejected toward the application target portion.

4. The inkjet printing method according to claim 1 or 2 wherein,

The landing position deviation characteristics are solved by the steps a) to E) shown below, and stored in the storage unit, the steps a) to E) including:

a) A step of positioning the inkjet head at the first rotation angle with the normal direction of the object plane of the coating object as a rotation axis, and ejecting droplets in a first print pattern,

B) A step of detecting a landing position deviation of the droplet ejected in the step A) from a target position shown by the first print pattern,

C) Positioning the ink jet head at the second rotation angle and ejecting liquid drops in a second printing pattern,

D) A step of detecting landing position deviation of the droplet ejected in the step C) from a target position shown by the second print pattern,

E) And a step of calculating the landing position deviation characteristic based on the landing position deviation detected in the B), the landing position deviation detected in the D), and the coordinates of the rotation axis of the inkjet head.

5. The method of inkjet printing according to claim 4 wherein,

In the third step, droplets are ejected from the inkjet head to the coating target portion under the condition that the relative movement speed between the inkjet head and the coating target is the same as the relative movement speed between the inkjet head and the coating target in the a) step and the relative movement speed between the inkjet head and the coating target in the C) step.

6. An inkjet printing apparatus for applying ink to an object to be coated by ejecting droplets from an inkjet head while relatively scanning the object to be coated,

The inkjet printing device is provided with:

A storage unit that stores landing position deviation characteristics that are calculated based on landing position deviations from a target position of droplets ejected from the inkjet head at first and second rotation angles that are different from each other, respectively; and

A calculation unit that calculates a target rotation angle of the inkjet head based on the landing position deviation characteristic, an arrangement pitch of the droplet discharge nozzles of the inkjet head, and a coating target pitch of the coating target in a direction orthogonal to a scanning direction, and generates a print pattern corresponding to the target rotation angle,

The inkjet printing device controls the inkjet head based on the target rotation angle and the print pattern, so that droplets are ejected to a coating target portion on the coating object.

7. The inkjet printing apparatus according to claim 6 wherein,

The inkjet printing device further includes:

a substrate adsorption stage for placing a substrate corresponding to the coating object;

A substrate rotation mechanism rotatably supporting a lower portion of the substrate suction table;

A substrate transfer table for displacing the substrate rotation mechanism and the substrate suction table;

A substrate transport position detection unit that detects a substrate transport position of the substrate transport table;

The inkjet head is disposed so as to face the substrate at an upper portion of the substrate;

A head rotation mechanism which is disposed above the inkjet head and which supports the inkjet head so as to be rotatable about a normal direction with respect to a plane of the substrate; and

A head displacement stage that displaces the inkjet head and the head rotation mechanism in a direction orthogonal to a displacement direction of the substrate conveyance stage and a direction of a rotation axis.