CN114290806A - Ink jet printing method and ink jet printing apparatus - Google Patents

Ink jet printing method and ink jet printing apparatus Download PDF

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Publication number
CN114290806A
CN114290806A CN202111156350.3A CN202111156350A CN114290806A CN 114290806 A CN114290806 A CN 114290806A CN 202111156350 A CN202111156350 A CN 202111156350A CN 114290806 A CN114290806 A CN 114290806A
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Prior art keywords
nozzles
ink
divided regions
nozzle
inkjet printing
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CN202111156350.3A
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Chinese (zh)
Inventor
熊泽谦太郎
吉田英博
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/07—Ink jet characterised by jet control
    • B41J2/11—Ink jet characterised by jet control for ink spray
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/21—Ink jet for multi-colour printing
    • B41J2/2132—Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding
    • B41J2/2139—Compensation for malfunctioning nozzles creating dot place or dot size errors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/21—Ink jet for multi-colour printing
    • B41J2/2132—Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding
    • B41J2/2142—Detection of malfunctioning nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J25/00—Actions or mechanisms not otherwise provided for
    • B41J25/001—Mechanisms for bodily moving print heads or carriages parallel to the paper surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J29/00—Details of, or accessories for, typewriters or selective printing mechanisms not otherwise provided for
    • B41J29/38—Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
    • B41J29/393—Devices for controlling or analysing the entire machine ; Controlling or analysing mechanical parameters involving printing of test patterns
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/10—Deposition of organic active material
    • H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
    • H10K71/13—Deposition of organic active material using liquid deposition, e.g. spin coating using printing techniques, e.g. ink-jet printing or screen printing
    • H10K71/135—Deposition of organic active material using liquid deposition, e.g. spin coating using printing techniques, e.g. ink-jet printing or screen printing using ink-jet printing

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  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Manufacturing & Machinery (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)

Abstract

An inkjet printing method for printing on a substrate while relatively moving the substrate and an inkjet head in which a plurality of nozzles are arranged along a straight line, the inkjet printing method comprising: dividing a coating region in the pixel bank on the substrate into a plurality of divided regions; a step of assigning the plurality of nozzles to the plurality of divided regions; selecting nozzles for ejecting ink to the divided regions at random from among the nozzles allocated to the respective divided regions; and a step of discharging ink from the selected nozzle to the plurality of divided regions while relatively moving the substrate and the inkjet head.

Description

Ink jet printing method and ink jet printing apparatus
Technical Field
The present disclosure relates to an inkjet printing method and an inkjet printing apparatus.
Background
In order to achieve a large area, high quality, and low cost, it is desirable to replace the semiconductor manufacturing process with a printing process for manufacturing a display. Examples of displays in which the manufacturing method can be replaced with a printing process include organic EL displays and quantum dot displays.
For example, an organic EL display generally has a functional layer containing an organic functional material disposed between an anode and a cathode. By the function of the organic functional material, an organic device such as a semiconductor element (transistor), a light-emitting element, or a liquid crystal element can be obtained. The semiconductor element includes, for example, an organic semiconductor material for connecting a source electrode and a drain electrode disposed on a substrate surface. The organic EL element has, for example, a light-emitting layer containing an organic EL material stacked on an anode electrode disposed on a substrate, and the light-emitting layer is sandwiched by a cathode electrode.
In order to pattern the functional material on the electrode, a barrier (i.e., a bank) surrounding the electrode surface may be formed, and a composition containing the functional material may be printed in an area defined by the bank. The bank may be made of resin. When printing ink containing a functional material on a region including an electrode surface defined by a bank, in general, it is preferable that the wettability of the region to be printed (including the electrode surface) is high, and that the wettability of the upper surface of the bank is low. This is to prevent ink from leaking out of the intended region. It is known that: in general, the fluorine component lowers the energy of the material surface and lowers the wettability.
The printing region defined by the bank is hereinafter referred to as a sub-pixel. The sub-pixels are typically arranged in a matrix. Ink is ejected from a plurality of nozzles arranged in a row and is caused to hit the sub-pixels. Then, the nozzles and the panel are moved relative to each other in a direction substantially perpendicular to the rows of the nozzles, and the ink is repeatedly hit, whereby all the sub-pixels in the matrix can be filled with the ink. In this step, when there is volume unevenness of the ink discharged between the nozzles, a portion where the amount of ink filled into the sub-pixel is large and a portion where the amount of ink is small are formed in a linear shape parallel to the printing direction. As a result, streaky light-emitting spots are generated in the completed display device, and the display device becomes defective. As a countermeasure, a method of randomly changing nozzles to be used and causing the variation in ink ejection volume per nozzle to be dispersed and hit each sub-pixel has been studied (for example, see patent document 1).
[ Prior Art document ]
Patent document 1: japanese patent No. 4984934
Disclosure of Invention
An inkjet printing method according to an aspect of the present disclosure prints on a substrate while relatively moving the substrate and an inkjet head in which a plurality of nozzles are arranged along a straight line, the inkjet printing method including: dividing a coating region in the pixel bank on the substrate into a plurality of divided regions; a step of assigning the plurality of nozzles to the plurality of divided regions; selecting nozzles for ejecting ink to the divided regions at random from among the nozzles allocated to the respective divided regions; and a step of discharging ink from the selected nozzle to the plurality of divided regions while relatively moving the substrate and the inkjet head.
An inkjet printing apparatus according to an aspect of the present disclosure includes: a table that holds a substrate; an inkjet head in which a plurality of nozzles are arranged in a row; a relative movement mechanism that relatively moves the stage and the inkjet head; and a control unit that performs: dividing a coating region in a pixel bank on the substrate into a plurality of divided regions; assigning the plurality of nozzles to the plurality of partitioned areas; selecting nozzles for ejecting ink to the divided regions at random from among the nozzles assigned to the respective divided regions; controlling the relative movement mechanism to move the substrate and the inkjet head relative to each other, and controlling the inkjet head to eject ink from the selected nozzle to the plurality of divided regions.
Drawings
Fig. 1 is a schematic view showing an inkjet printing apparatus according to a first embodiment of the present disclosure.
Fig. 2 is a schematic view showing an inkjet printing apparatus according to a second embodiment of the present disclosure.
Fig. 3 is a schematic view showing an inkjet printing apparatus according to a third embodiment of the present disclosure.
Fig. 4 is a schematic view showing an inkjet printing apparatus according to a fourth embodiment of the present disclosure.
Fig. 5 is a schematic view showing an inkjet printing apparatus according to a fifth embodiment of the present disclosure.
Fig. 6 is a schematic view showing an inkjet printing apparatus in the case where a first non-discharge coping process is performed according to a fifth embodiment of the present disclosure.
Fig. 7 is a schematic view showing an inkjet printing apparatus in the case where a second non-discharge coping process according to a fifth embodiment of the present disclosure is performed.
Description of reference numerals:
101. 201, 301, 401, 501 inkjet printing device
102 ink jet head
103 working table
104 relative movement mechanism
105. 205, 305, 405, 505 control unit
106 nozzle
110. 210, 310, 410, 510, 610 substrates
111. 211, 311, 511 pixel element
112. 212, 312, 412, 512, 612 sub-pixels
113. 213, 313, 413, 513, 613A, 613B, 613C partition region
114. 214, 414, 614 parting line
314. 514 first dividing line
315. 515 second dividing line
120 ink
121. 121A, 121B, 531 hit on the target position
506 Normal nozzle
506A first Normal nozzle
506B second Normal nozzle
506C third Normal nozzle
507 abnormal nozzle
530 inspecting a substrate
541 wave form generating device
542 Camera
D1 nozzle arrangement direction
D2 print direction.
Detailed Description
In the method described in patent document 1, the position of each sub-pixel and the position of the selected nozzle are changed for each pixel by random numbers. When the selected nozzle position is offset with respect to the sub-pixel, a bias in ink thickness and an uncoated region occur in the sub-pixel. This causes unevenness in the amount of light emitted in the sub-pixel. Further, when a nozzle to be discharged to a sub-pixel is clogged, a stripe-shaped light-emitting defective region is generated.
In view of the above circumstances, an object of the present disclosure is to provide an inkjet printing method and an inkjet printing apparatus capable of suppressing printing unevenness on a substrate.
Hereinafter, an embodiment of the present disclosure will be described. The configurations of the first to fifth embodiments described below can be combined in a range that can be achieved.
[ first embodiment ]
First, a first embodiment of the present disclosure is explained. Fig. 1 is a schematic view showing an inkjet printing apparatus according to a first embodiment of the present disclosure.
As shown in fig. 1, the inkjet printing apparatus 101 includes an inkjet head 102, a table 103, a relative movement mechanism 104, and a control unit 105.
On the inkjet head 102, a plurality of nozzles 106 are arranged in a line. Hereinafter, the arrangement direction of the plurality of nozzles 106 is sometimes referred to as a nozzle arrangement direction D1. The plurality of nozzles 106 may be arranged in two or more rows, and in this case, may be arranged in a so-called staggered arrangement. The plurality of nozzles 106 may be arranged in a direction inclined with respect to the printing direction D2 described later.
The stage 103 holds the substrate 110 at a position below the inkjet head 102 by vacuum suction or the like. On the substrate 110, pixel elements 111 are arranged in a matrix. The pixel element 111 is made up of a plurality of sub-elements 112 of, for example, RGB3 colors. Sub-picture elements 112 are coated areas within the picture element banks, for example formed in an oblong shape. The longitudinal direction in which the sub-pixel 112 is formed in an oblong shape is parallel to the nozzle arrangement direction D1. The sub-pixels 112 of 3 colors are arranged in a direction orthogonal to the nozzle arrangement direction D1. However, in the case of manufacturing a black and white display panel, the pixel element 111 is composed of 1 sub-pixel 112.
The relative movement mechanism 104 relatively moves the stage 103 and the inkjet head 102 in a direction orthogonal to the nozzle arrangement direction D1. In the first embodiment, the stage 103 is moved relative to the inkjet head 102 in the printing direction D2 shown in fig. 1. The inkjet head 102 may be moved relative to the table 103, or both the inkjet head 102 and the table 103 may be moved.
The control unit 105 controls the entire inkjet printing apparatus 101. The control unit 105 controls the relative movement mechanism 104 to move the table 103 in the printing direction D2, thereby passing the substrate 110 under the inkjet head 102. At this time, the control unit 105 controls the inkjet head 102 so that the ink 120 hits the aimed sub-pixel 112 and the ink 120 is ejected from the nozzle 106 at the same timing.
More specifically, the control unit 105 performs the dividing step, the distributing step, the selecting step, and the discharging step. The respective steps are explained below.
In the dividing step, the control unit 105 divides the subpixel 112 into a plurality of divided regions 113. In the configuration shown in fig. 1, the number of nozzles 106 that can hit the sub-pixels 112 with the ink 120 is 8 for each sub-pixel 112. The control unit 105 divides the sub-pixel 112 into, for example, 4 parts by the dividing line 114, and sets 4 divided regions 113. When the printing direction D2 is set to the front, the control unit 105 divides the sub-pixel 112 into left and right parts.
In the distribution step, the control unit 105 distributes the nozzles 106 constituting the inkjet head 102 to the plurality of divided regions 113. The control unit 105 allocates, for example, 2 nozzles 106 to each of the divided regions 113, which enable the ink 120 to hit 1 subpixel 112.
In the selection step, the control unit 105 randomly selects the nozzles 106 that eject the ink 120 to the divided regions 113 from among the nozzles 106 assigned to the respective divided regions 113 using random numbers. The control unit 105 selects the number of nozzles 106 that is 50% or more of the total number of nozzles 106 allocated to the 1 divided region 113. In the first embodiment, 1 nozzle 106 is selected for each divided region 113. The control unit 105 may not use a random number when randomly selecting the nozzle 106.
In the ejection step, the control unit 105 controls the relative movement mechanism 104 to move the table 103, and controls the inkjet head 102 to eject the ink 120 from the nozzle 106 selected in the selection step. At this time, the control unit 105 controls the inkjet head 102 so that the volume of the ink ejected for each of the divided regions 113 is within ± 50% of the average volume of the ink ejected for the divided regions 113, and causes the ink 120 to be ejected from the nozzles 106 in the ejection step. That is, the control unit 105 controls the inkjet head 102 so as to satisfy the following expression (1).
Figure BDA0003286856850000061
b: division number of sub-pixel
Vi: volume of ink ejected to No. i divided region
Fig. 1 shows the impact target position 121 of the ink 120 ejected to each divided region 113 and the nozzle 106 from which the ink 120 is not ejected. In fig. 1, the ink 120 is shown by a gray-colored circle, and the hit target position 121 is shown by a dashed circle. The ink 120 wets and spreads in a substantially concentric circle from the target position. The number of sub-pixels 112 divided in the dividing step, the selection probability of the nozzle 106 for ejecting the ink 120 in the selecting step, and the ejection volume and the number of droplets of the ink 120 controlled in the ejecting step are set so that the entire divided regions 113 are filled with the wet spread. In order to satisfy the requirement of the volume of the ink 120 based on the above expression (1), it is desirable to increase the randomness of the film thickness, that is, the variation of the combination of the nozzles 106. When the number of nozzles 106 allocated to each divided region 113 is n and the number of nozzles 106 ejecting ink 120 is r, the combination K is expressed by the following expression (2). Further, as shown in the following expression (3), by setting r to about one-half of n, the combination of the nozzles 106 can be maximized.
Figure BDA0003286856850000062
r≈n/2 ···(3)
As described above, the control unit 105 divides the sub-pixel 112 into the plurality of divided regions 113, and allocates the plurality of nozzles 106 of the inkjet head 102 to the plurality of divided regions 113. The control unit 105 randomly selects nozzles 106 for ejecting ink to the divided regions 113 from among the nozzles 106 assigned to the respective divided regions 113, and ejects ink 120 from the selected nozzles 106 to the plurality of divided regions 113. Therefore, by discharging the ink 120 to each of the divided regions 113, it is possible to prevent the sub-pixel 112 from having a region not covered with the ink 120, and to change the thickness of the ink 120 randomly for each of the divided regions 113. Therefore, the bias of the film thickness of the ink 120 parallel to the printing direction D2 can be reduced, and the occurrence of stripe-shaped printing unevenness on the substrate 110 can be suppressed. As a result, flare of the substrate can be suppressed.
[ second embodiment ]
Next, a second embodiment of the present disclosure is explained. Fig. 2 is a schematic view showing an inkjet printing apparatus according to a second embodiment of the present disclosure. The same components as those of the inkjet printing apparatus 101 according to the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
A plurality of pixel elements 211 are arranged on the substrate 210 of the second embodiment. The pixel element 211 is made up of 3 color sub-elements 212. Sub-pixel element 212 is a coated area within a pixel bank, e.g., a substantially square with corners formed as a curve.
The control section 205 of the inkjet printing apparatus 201 executes the dividing step, the dispensing step, the selecting step, and the discharging step.
The control unit 205 divides the subpixel 212 into a plurality of divided regions 213 in the dividing step. In the configuration shown in fig. 2, the number of nozzles 106 that can hit the sub-pixels 212 with the ink 120 is 3 for each sub-pixel 212. The control unit 205 divides the sub-pixel 212 into, for example, 3 parts by the dividing line 214, and sets 3 divided regions 213. When the printing direction D2 is set to the front, the control unit 205 divides the sub-pixel 212 into front and rear parts.
In the allocation step, the control unit 205 allocates all of the 3 nozzles 106 that can hit the ink 120 on the 1 subpixel 212 to the 1 divided region 213. That is, the control unit 205 can hit the ink 120 from the 3 nozzles 106 on the 3 divided regions 213 constituting the 1 subpixel 212.
In the selection step, the control unit 205 randomly selects the nozzles 106 that eject the ink 120 to the divided regions 213 using random numbers. The control unit 205 selects the number of nozzles 106 that is 50% or more of the total number of nozzles 106 allocated to the 1 divided region 213. In the second embodiment, 2 nozzles 106 are selected for each of the divided regions 213.
In the ejection step, the control unit 205 ejects the ink 120 from the nozzle 106 selected in the selection step so as to satisfy the above expression (1), thereby performing printing.
Fig. 2 shows the impact target positions 121 of the ink 120 discharged to the respective divided regions 213 and the nozzles 106 from which the ink 120 is not discharged. In the second embodiment, there is a fear that the sub-pixel 212 having the biased coating position is generated. For example, in the sub-pixel 212 No. 2 from the bottom in the 2 nd row from the left in fig. 2, the impact target positions 121 of the nozzles 106 that do not eject the ink 120 are aligned in a row, and the application position of the ink 120 is shifted to the left side from the center. Therefore, in order to wet-spread the ink 120 into the entire sub-pixel 212 even in such a case, the number of nozzles 106 for ejecting the ink 120 needs to be determined in consideration of the wet spread of the ink 120 into the sub-pixel 212 and the shape of the sub-pixel 212. For example, when the diameter of the nozzle 106 is 20 μm, the diameter of the ejected liquid droplet is approximately 20 μm. The wetting extension of the hit drop is largely controlled by the wettability of subpixel element 212. The contact angle of the liquid droplet hit on the surface may exceed 10 degrees, and the liquid droplet may spread from a wet state with a diameter of approximately 20 μm to a contact angle of 0 degree, which is called wet spreading. For example, when the pitch of the nozzles 106 is 20 μm, the size of the sub-pixels 212 in the nozzle arrangement direction D1 is 60 μm, and the droplet diameter of the ink 120 after wet spreading over the sub-pixels 212 is 60 μm, the ink 120 can be wet spread in the sub-pixels 212 even in the sub-pixels 212 having an offset application position. The inkjet printing method according to the second embodiment is effective when the ejection pitch in the printing direction D2 can be shortened, and when the shape of the sub-pixel 212 is long in the printing direction D2 and short in the nozzle arrangement direction D1.
[ third embodiment ]
Next, a third embodiment of the present disclosure is explained. Fig. 3 is a schematic view showing an inkjet printing apparatus according to a third embodiment of the present disclosure. The same components as those of the inkjet printing apparatus 101 according to the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
A plurality of pixel elements 311 are arranged on the substrate 310 of the third embodiment. The pixel element 311 is constituted by 3-color sub-elements 312 arranged in the printing direction D2. The sub-pixel 312 is a coating region in the pixel bank, and is formed in an oblong shape similar to the sub-pixel 112 of the first embodiment.
The control section 305 of the inkjet printing apparatus 301 performs the dividing step, the dispensing step, the selecting step, and the discharging step.
In the dividing step, the control unit 305 divides the sub-pixel 312 into a plurality of divided regions 313. In the configuration shown in fig. 3, the number of nozzles 106 that can hit the sub-pixels 312 with the ink 120 is 8 for each sub-pixel 312. The control unit 305 divides the sub-pixel 312 into 4 parts by a first dividing line 314 parallel to the nozzle arrangement direction D1 and a second dividing line 315 parallel to the printing direction D2, and sets 4 divided regions 313. When the printing direction D2 is set to the front, the control unit 305 divides the sub-pixel 312 into front and rear parts and left and right parts.
In the allocation step, the control unit 305 allocates 4 nozzles 106, for example, to 2 divided regions 313 arranged on the left and right, which are 8 nozzles 106 capable of causing the ink 120 to hit 1 subpixel 312. That is, the control unit 305 can hit the ink 120 from the 4 nozzles 106 on the 4 divided regions 313 constituting the 1 subpixel 312.
In the selection step, the control unit 305 randomly selects the nozzles 106 that eject the ink 120 to the divided regions 313 using random numbers. The controller 305 selects the number of nozzles 106 that is 50% or more of the total number of nozzles 106 allocated to the 1 divided region 313. In the third embodiment, 2 nozzles 106 are selected for each divided region 313.
In the ejection step, the control unit 305 ejects the ink 120 from the nozzles 106 selected in the selection step so as to satisfy the above expression (1), thereby performing printing.
Fig. 3 shows the impact target position 121 of the ink 120 ejected to each divided region 313 and the nozzle 106 from which the ink 120 is not ejected. In the third embodiment, since the sub-pixels 312 can be arbitrarily divided in the front, rear, left, and right directions with the printing direction D2 as the front, even when the sub-pixels 312 are large, for example, it is possible to effectively prevent the sub-pixels 312 from being filled with the ink 120. In the third embodiment, when a plurality of first dividing lines 314 are provided, that is, when the sub-pixels 312 are divided into front and rear 3 or more, it is necessary to perform printing at a low speed by reducing the relative movement speed of the inkjet head 102 and the stage 103 in response to high-frequency ejection by the inkjet head 102. For high-definition display production, the inkjet head 102 narrows the aperture of the nozzle 106, narrowing the pitch. The third embodiment is effective in the case of manufacturing a plurality of products in 1 line, such as the case of manufacturing a low-definition large-screen display using the inkjet head 102.
[ fourth embodiment ]
Next, a fourth embodiment of the present disclosure is explained. Fig. 4 is a schematic view showing an inkjet printing apparatus according to a fourth embodiment of the present disclosure. The same components as those of the inkjet printing apparatus 101 according to the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
A sub-pixel 412 constituting a pixel is arranged on the substrate 410 of the fourth embodiment. Sub-pixel element 412 is a coated area within a pixel bank, and is formed in an oblong shape similar to sub-pixel element 112 of the first embodiment.
The control unit 405 of the inkjet printing apparatus 401 executes the dividing step, the dispensing step, the selecting step, and the discharging step.
In the dividing step, the control unit 405 divides the subpixel 412 into a plurality of divided regions 413. When the printing direction D2 is set to the front, the control unit 405 divides the subpixel 412 into 2 parts on the left and right. In the configuration shown in fig. 4, the number of nozzles 106 that the ink 120 hits on the sub-pixels 412 can be 7, that is, an odd number for each sub-pixel 412. When the number of nozzles 106 that can hit 1 subpixel 412 with the ink 120 is odd, the nozzles 106 cannot be equally distributed to the divided regions 413 by the number other than 1 as in the case of the even number. In the fourth embodiment, the control unit 405 randomly decides the division position in the sub-pixel 412 using, for example, a random number. In this case, the control unit 405 may vary the division position for each sub-pixel 412 based on the bent division line 414. In the fourth embodiment, the configuration in which the sub-pixels 412 are divided so that the number of nozzles 106 allocated to each of the left and right divided regions 413 is 2 and 5, 3 and 4, and 4 and 3 is exemplified, but the sub-pixels 412 may be divided so that the number of nozzles is 1 or 6.
In the allocation step, the controller 405 allocates the number of 7 nozzles 106 that can hit the ink 120 on the 1 subpixel 412, for example, to each of the 2 divided regions 413 arranged on the left and right, the number corresponding to the size of each divided region 413.
In the selection step, the control unit 405 randomly selects the nozzles 106 that eject the ink 120 to the divided regions 413 using random numbers. In the fourth embodiment, the configuration in which 2 or 1 nozzle 106 out of 3 nozzles 106 allocated to each divided region 413, 3 or 2 or 1 nozzle 106 out of 4 nozzles 106, and 3 or 2 or 1 nozzle 106 out of 5 nozzles 106 are selected is exemplified, but selection may be made as follows, for example. When the number of nozzles 106 allocated to each of the left and right divided regions 413 is 1 and 6, the control unit 405 may select 1 nozzle 106 of the left divided region 413 and select 4 nozzles 106 of the 6 nozzles 106 of the right divided region 413. The controller 405 may select the number of nozzles 106 that is 50% or more of the total number of nozzles 106 allocated to the 1 divided region 413.
In the ejection step, the control unit 405 ejects the ink 120 from the nozzle 106 selected in the selection step so as to satisfy the above expression (1), thereby performing printing.
Fig. 4 shows the impact target positions 121 of the ink 120 ejected to the respective divided regions 413 and the nozzles 106 that do not eject the ink 120. Preferably, the number of nozzles 106 that eject ink 120 is the same for each sub-pixel 412. However, the volume unevenness of the ink 120 in each sub-pixel 412 is not limited to this when it is within the range required for the finished display. For example, the variation in ink thickness (film thickness) of each sub-pixel 412 may be within a range of ± 50% of the average ink thickness of all sub-pixels 412. When the above description is generalized, the following expressions (4) and (5) are given.
Figure BDA0003286856850000111
L: the number of nozzles capable of hitting ink on the sub-pixel
ni: number of nozzles allocated to divided regions
b: division number of sub-pixel
Figure BDA0003286856850000112
Z [ j ]: the number of nozzles that hit the sub-pixel with ink
j: number of any sub-pixel
ri: the number of nozzles that hit the ink in the divided area
[ fifth embodiment ]
Next, a fifth embodiment of the present disclosure is explained. Fig. 5 is a schematic view showing an inkjet printing apparatus according to a fifth embodiment of the present disclosure. Fig. 6 is a schematic view showing the inkjet printing apparatus when the first non-ejection coping process is performed. Fig. 7 is a schematic view showing the inkjet printing apparatus when the second non-discharge coping process is performed. The same components as those of the inkjet printing apparatus 101 according to the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
As shown in fig. 5 and 6, the inkjet printing device 501 includes an inkjet head 102, a table 103, a relative movement mechanism 104, a control unit 505 including a computer, a waveform generation device 541, and a camera 542.
As shown in fig. 6, a plurality of pixel elements 511 are arranged on a substrate 510 of the fifth embodiment. The pixel element 511 is composed of 3-color sub-elements 512 arranged in the printing direction D2. As shown in fig. 7, a plurality of sub-pixels 612 are arranged on a substrate 610 of the fifth embodiment. The sub-pixels 512 and 612 are coating regions in the pixel banks, and are formed in an oblong shape similar to the sub-pixel 112 of the first embodiment.
The waveform generation device 541 outputs the ejection waveform to the inkjet head 102 based on an output command from the control unit 505. The inkjet head 102 ejects ink 120 from a predetermined nozzle 106 at a predetermined timing based on an ejection waveform. The camera 542 acquires an image for inspecting the ink 120 that has hit the inspection substrate 530 shown in fig. 5, and outputs the image to the control unit 505.
The control unit 505 of the inkjet printing apparatus 501 executes an inspection step, a dividing step, a dispensing step, a selecting step, and a discharging step.
In the inspection step, the control unit 505 controls the relative movement mechanism 104 and the inkjet head 102 so that the ink 120 hits the inspection substrate 530 held on the stage 103 from all the nozzles 106 of the inkjet head 102. The camera 542 outputs an image of the inspection substrate 530 to the control unit 505. The control unit 505 determines the position of the ink 120 hitting the inspection substrate 530, the droplet size, and the presence or absence of ejection. When the hitting target position on the substrate 530 where the ink 120 should originally be present is checked and the ink 120 is not present, the control unit 505 determines the nozzle 106 that should eject the ink 120 to the hitting target position as the abnormal nozzle 507. For example, in the case where the ink 120 is not present at the impact target position 531 shown by a dashed circle in fig. 5, the control unit 505 determines the nozzle 106 that is supposed to eject the ink 120 to the impact target position 531 as the abnormal nozzle 507, for example, based on a preset relationship between the impact target position and the position of the nozzle 106. In the following, the nozzles 106 capable of ejecting the ink 120 may be referred to as normal nozzles 506. In fig. 5 to 7, the normal nozzles 506 are shown by simple circles, and the abnormal nozzles 507 are shown by circles hatched with oblique lines.
When the abnormal nozzle 507 is not found in the inspection step, the control unit 505 performs the dividing step, the distributing step, the selecting step, and the discharging step, which are similar to those of the first to fourth embodiments. In the ejection step, the controller 505 causes the waveform generator 541 to output an ejection waveform assuming that the abnormal nozzle 507 is not present. On the other hand, when the abnormal nozzle 507 is found in the inspection step, the control unit 505 executes the following first non-discharge handling process or second non-discharge handling process.
[ first countermeasure against blowout ]
In the configuration shown in fig. 6, the number of nozzles 106 that can hit the sub-pixels 512 with the ink 120 is 7 for each sub-pixel 512. In the dividing step, the control unit 505 divides the subpixel 512 into a plurality of divided regions 513 using random numbers as in the fourth embodiment. The control unit 505 divides the sub-pixel 512 into 2 divided regions 513 via the bent first dividing line 514.
The control unit 505 does not change the size of the divided region 513 divided via the first dividing line 514 for the sub-pixel 512 in which the abnormal nozzle 507 is not present among the nozzles 106 that can be hit by the ink 120. The control unit 505 changes the size of the divided region 513 by changing the first dividing line 514, which is bent, to the second dividing line 515, which is a straight line, for the sub-pixel 512 having the abnormal nozzle 507 among the nozzles 106 that can be hit by the ink 120. At this time, the control unit 505 preferably sets the divided region 513 so that at least 2 or more normal nozzles 506 are allocated to the divided region 513 to which the abnormal nozzle 507 is allocated.
In the allocation step, the control unit 505 allocates the number of normal nozzles 506 corresponding to the size of 2 divided regions 513 to the divided regions 513 divided by the first dividing line 514. In the allocation step, the control unit 505 allocates the number of the abnormal nozzles 507 and the number of the normal nozzles 506 corresponding to the size of the divided region 513 to the divided region 513 divided by the second dividing line 515.
In the selection step, the control unit 505 randomly selects the normal nozzles 506 that eject the ink 120 to the divided regions 513 using random numbers. The control unit 505 selects normal nozzles 506 in a number of 50% or more of the total number of normal nozzles 506 allocated to 1 divided region 513. That is, the control unit 505 selects the number of nozzles 106 (2 normal nozzles 506 out of 3 normal nozzles 506 in the example of fig. 6) that is 50% or more of the total number of nozzles 106 other than the abnormal nozzles 507 in the divided region 513 to which the abnormal nozzles 507 are assigned.
In the ejection step, the control unit 505 performs printing by ejecting the ink 120 from the normal nozzles 506 selected in the selection step so as to satisfy the above expression (1). At this time, the controller 505 causes the waveform generator 541 to output an ejection waveform assuming that the abnormal nozzle 507 is present. The inkjet head 102 ejects the ink 120 from only the normal nozzles 506 based on the ejection waveform from the waveform generation device 541. It is assumed that: when the abnormal nozzle 507 exists, the arrangement range of the remaining 6 normal nozzles 506 is biased to the right or left side (the right side in the example of fig. 6) within the sub-pixel 512. In this case, the relative position of the inkjet head 102 with respect to the substrate 510 can be corrected within a range that is allowed by the printing position of the other sub-pixels 512, and the arrangement range of the 6 normal nozzles 506 can be located at the center of the sub-pixels 512.
[ second countermeasure against squirting ]
In the configuration shown in fig. 7, the number of nozzles 106 that can hit the sub-pixels 612 with the ink 120 is 8 for each sub-pixel 612. In the dividing step, the control unit 505 divides the subpixel 612 into a plurality of (2 in the example of fig. 7) divided regions 613 via straight dividing lines 614.
In the allocation step, the control unit 505 allocates the number of nozzles 106 (4 nozzles in the example of fig. 7) corresponding to the size of the divided region 613 to each divided region 613. For example, in the example of fig. 7, the control unit 505 allocates 4 nozzles 106 to the leftmost 4 divided regions 613 arranged in the printing direction D2. The 4 nozzles 106 are arranged in the order of the first normal nozzle 506A, the abnormal nozzle 507, the second normal nozzle 506B, and the third normal nozzle 506C from the left side.
In the selection step, the control unit 505 randomly selects the nozzles 106 that eject the ink 120 to the divided regions 613 using random numbers. The control unit 505 selects the number of nozzles 106 (3 of the 4 nozzles 106 in the example of fig. 7) that is 50% or more of the total number of nozzles 106 allocated to the 1 divided region 613. When the selected nozzle 106 includes the abnormal nozzle 507, the control unit 505 performs at least one of the following first reselection step and second reselection step.
First, the first reselection process will be described. When the first normal nozzle 506A, the abnormal nozzle 507, and the third normal nozzle 506C are selected in the selection step for the lowermost divided region 613A of the leftmost 4 divided regions 613, the control unit 505 reselects the second normal nozzle 506B, which is not selected in the selection step, instead of the abnormal nozzle 507 in the first reselection step. Then, in the ejection step, the control unit 505 ejects the ink 120 from the first to third normal nozzles 506A to 506C to the divided area 613A so as to satisfy the above expression (1), thereby performing printing. That is, in the hit target position 121A, the ink 120 from the abnormal nozzle 507 should be hit, but the ink 120 cannot be ejected from the abnormal nozzle 507, and therefore the ink 120 from the second normal nozzle 506B is hit at the hit target position 121B which is not intended to be hit.
Next, the second reselection step will be described. When the first normal nozzle 506A, the abnormal nozzle 507, and the second normal nozzle 506B are selected in the selection step for the divided area 613B located No. 2 from among the leftmost 4 divided areas 613, the control unit 505 selects the first normal nozzle 506A selected in the selection step again instead of the abnormal nozzle 507 in the second reselection step, and discharges the ink 120 as the normal nozzle 506 instead of the abnormal nozzle 507. Then, in the ejection step, the control unit 505 ejects the ink 120 from the first and second normal nozzles 506A and 506B to the divided regions 613B so as to satisfy the above expression (1), thereby performing printing. At this time, the controller 505 ejects the ink 120 from the first normal nozzles 506A 2 times at different timings with respect to the divided regions 613B.
When the abnormal nozzle 507, the second normal nozzle 506B, and the third normal nozzle 506C are selected in the selection step for the divided area 613C located No. 2 from among the leftmost 4 divided areas 613, the control unit 505 may select the second normal nozzle 506B again in place of the abnormal nozzle 507 in the second reselection step and discharge the normal nozzles 506 of the ink 120 in place of the abnormal nozzle 507. In this case, in the ejection step, the ink 120 is ejected from the second and third normal nozzles 506B, 506C to the divided regions 613C so as to satisfy the above expression (1). At this time, the ink 120 is ejected 2 times from the second normal nozzles 506B at different timings for the divided regions 613C.
According to the second non-ejection coping process described above, even in the case where the abnormal nozzle 507 is present, the fixing of the ejected normal nozzles 506 can be prevented in the region along the printing direction D2 printed by the normal nozzles 506 adjacent to the abnormal nozzle 507, and the occurrence of the region not covered with the ink 120 in the sub-pixel 612 can be prevented, and the film thickness of the ink 120 can be randomly changed for each divided region 613.
According to the inkjet printing method and inkjet printing apparatus of the present disclosure, printing unevenness of a substrate can be suppressed.
[ industrial applicability ]
The inkjet printing method and inkjet printing apparatus according to the present disclosure can produce a display, which is an example of a substrate, with high quality even when volume unevenness occurs for each nozzle during production. The inkjet printing method and inkjet printing apparatus according to the present disclosure are applicable not only to displays but also to devices formed on a substrate by printing, such as illumination, sensors, and solar cells, and are therefore extremely useful and highly industrially applicable.

Claims (12)

1. An inkjet printing method for printing on a substrate while relatively moving the substrate and an inkjet head in which a plurality of nozzles are arranged along a straight line,
the inkjet printing method includes:
dividing a coating region in the pixel bank on the substrate into a plurality of divided regions;
a step of assigning the plurality of nozzles to the plurality of divided regions;
selecting nozzles for ejecting ink to the divided regions at random from among the nozzles allocated to the respective divided regions; and
and discharging ink from the selected nozzle to the plurality of divided regions while relatively moving the substrate and the inkjet head.
2. The inkjet printing method according to claim 1,
the step of ejecting the ink includes: and ejecting ink from the selected nozzle such that the volume of ink ejected to each of the plurality of divided regions is within ± 50% of the average volume of ink ejected to the plurality of divided regions.
3. The inkjet printing method according to claim 1 or 2,
the step of selecting the nozzle comprises: selecting a number of nozzles that is 50% or more of the total number of nozzles allocated to the divided region.
4. The inkjet printing method according to any one of claims 1 to 3,
the step of dividing the coating region into a plurality of divided regions includes: and dividing the application region into left and right regions with the moving direction of the substrate relative to the inkjet head set to the front.
5. The inkjet printing method according to any one of claims 1 to 3,
the step of dividing the coating region into a plurality of divided regions includes: and a step of dividing the application region into front and rear portions with the moving direction of the substrate relative to the inkjet head set to the front.
6. The inkjet printing method according to any one of claims 1 to 3,
the step of dividing the coating region into a plurality of divided regions includes: and a step of dividing the application region into front and rear portions and left and right portions, with the direction of movement of the substrate relative to the inkjet head set to the front.
7. The inkjet printing method according to any one of claims 1 to 6,
forming a plurality of the coating regions on the substrate,
the step of dividing the coating region into a plurality of divided regions includes: and a step of making the dividing position in at least one of the coating regions different from the dividing positions in the other coating regions.
8. The inkjet printing method according to any one of claims 1 to 7,
the step of assigning the plurality of nozzles to the plurality of divided regions includes: and a step of differentiating the number of nozzles assigned to at least one of the divided regions from the number of nozzles assigned to the other divided regions.
9. The inkjet printing method according to any one of claims 1 to 8,
the inkjet printing method further includes: determining whether or not there is an abnormal nozzle incapable of ejecting ink among the plurality of nozzles,
when the abnormal nozzle exists, the step of selecting the nozzle comprises the following steps: and selecting nozzles for ejecting ink to the divided regions from among the nozzles allocated to the divided regions, the nozzles being other than the abnormal nozzles.
10. The inkjet printing method according to any one of claims 1 to 8,
the inkjet printing method further includes: determining whether or not there is an abnormal nozzle incapable of ejecting ink among the plurality of nozzles,
the step of ejecting the ink in the case where the abnormal nozzle exists includes: and ejecting ink from nozzles, which are not selected as nozzles for ejecting ink to the divided regions, among the nozzles allocated to the application regions together with the abnormal nozzles, in place of the abnormal nozzles.
11. The inkjet printing method according to any one of claims 1 to 8,
the inkjet printing method further includes: determining whether or not there is an abnormal nozzle incapable of ejecting ink among the plurality of nozzles,
the step of ejecting the ink in the case where the abnormal nozzle exists includes: and ejecting ink from a nozzle selected as a nozzle for ejecting ink to the divided region among the nozzles allocated to the application region together with the abnormal nozzle, instead of the abnormal nozzle.
12. An ink-jet printing apparatus, wherein,
the inkjet printing apparatus includes:
a table that holds a substrate;
an inkjet head in which a plurality of nozzles are arranged in a row;
a relative movement mechanism that relatively moves the stage and the inkjet head; and
a control part for controlling the operation of the display device,
the control unit performs the following processing:
dividing a coating region in a pixel bank on the substrate into a plurality of divided regions;
assigning the plurality of nozzles to the plurality of partitioned areas;
selecting nozzles for ejecting ink to the divided regions at random from among the nozzles assigned to the respective divided regions;
controlling the relative movement mechanism to move the substrate and the inkjet head relative to each other, and controlling the inkjet head to eject ink from the selected nozzle to the plurality of divided regions.
CN202111156350.3A 2020-10-08 2021-09-29 Ink jet printing method and ink jet printing apparatus Pending CN114290806A (en)

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