KR20230120193A - Inkjet printing apparatus and method of inkjet printing - Google Patents

Abstract

An inkjet printing device is provided. An inkjet printing apparatus according to an embodiment includes at least a stage on which a substrate is seated; a nozzle unit disposed above the stage and ejecting ink containing a solvent in which the bipolar element is dispersed on the substrate; A plurality of optical sensor units disposed adjacent to the nozzle unit, wherein the nozzle unit includes: an excitation unit configured to excite the bipolar element; and a plurality of light transmitting units through which first light emitted from the excited bipolar element is transmitted, and each of the plurality of optical sensor units may be disposed to face each of the plurality of light transmitting units of the nozzle unit.

Description

Inkjet printing apparatus and inkjet printing method {INKJET PRINTING APPARATUS AND METHOD OF INKJET PRINTING}

The present invention relates to an inkjet printing device and an inkjet printing method.

The importance of display devices is increasing along with the development of multimedia. In response to this, various types of display devices such as organic light emitting displays (OLEDs) and liquid crystal displays (LCDs) are being used.

A device for displaying an image of a display device includes a display panel such as an organic light emitting display panel or a liquid crystal display panel. Among them, the light emitting display panel may include a light emitting element. For example, in the case of a light emitting diode (LED), an organic light emitting diode (OLED) using an organic material as a fluorescent material, and an inorganic material as a fluorescent material and inorganic light emitting diodes.

An inorganic light emitting diode using an inorganic semiconductor as a fluorescent material has durability even in a high-temperature environment and has a higher efficiency of blue light than an organic light emitting diode.

An object to be solved by the present invention is to provide an inkjet printing device capable of replenishing a small amount of light emitting diode elements in real time.

Another problem to be solved by the present invention is to provide an inkjet printing method capable of replenishing discharged light emitting diode devices in real time.

The tasks of the present invention are not limited to the tasks mentioned above, and other technical tasks not mentioned will be clearly understood by those skilled in the art from the following description.

An inkjet printing apparatus according to an embodiment for solving the above problems includes at least a stage on which a substrate is seated; a nozzle unit disposed above the stage and ejecting ink containing a solvent in which the bipolar element is dispersed on the substrate; A plurality of optical sensor units disposed adjacent to the nozzle unit, wherein the nozzle unit includes: an excitation unit configured to excite the bipolar element; and a plurality of light transmitting units through which first light emitted from the excited bipolar element is transmitted, and each of the plurality of optical sensor units may be disposed to face each of the plurality of light transmitting units of the nozzle unit.

An inkjet printing method according to an embodiment for solving the above problems is to prepare a nozzle unit including at least a plurality of discharge ports for ejecting ink containing a solvent in which the bipolar element is dispersed and an excitation unit for exciting the bipolar element. step; exciting the bipolar element by emitting a first light from the excitation unit; sensing an amount of second light emitted from the excited bipolar device; measuring the number of bipolar elements discharged through each of the plurality of discharge ports by sensing the amount of light; and further discharging the ink from a first outlet in which the number of bipolar elements is measured among the plurality of outlets, wherein the nozzle unit may include a light transmitting portion through which the second light is transmitted.

An inkjet printing device according to an embodiment may replenish a light emitting diode element discharged less in real time.

The inkjet printing method according to an exemplary embodiment may replenish a light emitting diode element discharged less in real time.

Effects according to the embodiments are not limited by the contents exemplified above, and more various effects are included in this specification.

1 is a perspective view schematically illustrating an inkjet printing apparatus according to an exemplary embodiment.
FIG. 2 is a schematic diagram illustrating an operation of an inkjet head unit of the inkjet printing apparatus according to the embodiment of FIG. 1 .
FIG. 3 is a structural diagram schematically illustrating a connection relationship between an ink storage unit and an inkjet head unit of the inkjet printing apparatus according to the embodiment of FIG. 1 .
FIG. 4 is a perspective view schematically illustrating a nozzle unit and an optical sensor unit of the inkjet printing apparatus according to the embodiment of FIG. 1 .
5 is a perspective view schematically illustrating the nozzle unit of FIG. 4 .
6 is a structural diagram schematically showing the inside of the nozzle unit of FIG. 4 .
FIG. 7 is an enlarged view of a region Q1 of FIG. 6 .
8 is a cross-sectional view showing a schematic cross-section taken along the line X1-X1′ of FIG. 4 .
9 and 10 are diagrams for explaining a real-time bipolar element replenishment process of the inkjet printing apparatus according to the embodiment of FIG. 1 .
FIG. 11 is a schematic plan view of the probe device of the inkjet printing apparatus according to the embodiment of FIG. 1 viewed from a third direction.
12 and 13 are schematic diagrams illustrating the operation of the probe device of FIG. 11 .
FIG. 14 is a schematic diagram illustrating alignment of solids inside ink by generating an electric field on a target substrate by the probe device of FIG. 11;
15 is a schematic plan view of a display device according to an exemplary embodiment.
FIG. 16 is a layout diagram schematically illustrating the structure of one pixel of the display device according to the exemplary embodiment of FIG. 15 .
17 is a schematic diagram of a light emitting element of the display device according to the exemplary embodiment of FIG. 15 .
18 is a cross-sectional view taken along lines Xa-Xa′, Xb-Xb′, and Xc-Xc′ of FIG. 16 .
19 to 21 are schematic diagrams illustrating a manufacturing method of the display device according to the exemplary embodiment of FIG. 15 .
22 is a structural diagram schematically illustrating the inside of a nozzle unit of an inkjet printing apparatus according to another embodiment.
23 and 24 are diagrams for explaining a nozzle part of an inkjet printing apparatus according to another embodiment.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the holder of the scope of the invention, and the present invention is only defined by the scope of the claims.

When an element or layer is referred to as “on” another element or layer, it includes all cases where another element or layer is directly on top of another element or another layer or another element is interposed therebetween. Likewise, those referred to as "lower", "left", and "right" include all cases in which other elements are interposed immediately adjacent to or interposed with other elements or other elements in the middle. Like reference numbers designate like elements throughout the specification.

Although first, second, etc. are used to describe various components, these components are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first element mentioned below may also be the second element within the technical spirit of the present invention.

Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each embodiment can be implemented independently of each other or can be implemented together in a related relationship. may be

Hereinafter, specific embodiments will be described with reference to the accompanying drawings.

1 is a perspective view schematically illustrating an inkjet printing apparatus according to an exemplary embodiment. FIG. 2 is a schematic diagram illustrating an operation of an inkjet head unit of the inkjet printing apparatus according to the embodiment of FIG. 1 . FIG. 3 is a structural diagram schematically illustrating a connection relationship between an ink storage unit and an inkjet head unit of the inkjet printing apparatus according to the embodiment of FIG. 1 .

In FIG. 1 , a first direction DR1 , a second direction DR2 , and a third direction DR3 are defined. The first direction DR1 and the second direction DR2 are perpendicular to each other, the first direction DR1 and the third direction DR3 are perpendicular to each other, and the second and third directions DR2 and DR3 are may be perpendicular to each other. It can be understood that the first direction DR1 means the horizontal direction in the drawing, the second direction DR2 means the vertical direction in the drawing, and the third direction DR3 means the upper and lower directions in the drawing. there is. In the following specification, unless otherwise specified, "direction" may refer to both directions extending along the direction toward both sides. In addition, when it is necessary to distinguish both “directions” extending to both sides, one side is referred to as “one direction” and the other side is referred to as “the other side of the direction”. Referring to FIG. 1 , a direction indicated by an arrow is referred to as one side, and an opposite direction is referred to as the other side.

1 to 3, the inkjet printing apparatus 1 according to an embodiment includes a stage STG on which a target substrate SUB is seated, and an inkjet head unit 100 on which a plurality of nozzle units 300 are disposed. , the base frame 600, the ink storage unit 500, the first connector IL1 connecting the ink jet head unit 100 and the ink storage unit 500, and the ink jet head unit 100 and the ink storage unit 500. ) and a second connector IL2 connecting the An inkjet printing apparatus 1 according to an exemplary embodiment applies a predetermined ink 90 onto a target substrate SUB mounted on a stage STG by using an inkjet head unit 100 and a plurality of nozzle units 300. can be sprayed into

The stage STG may serve to seat the target substrate SUB. The stage STG may be disposed on a first rail RL1 extending in the second direction DR2 and a second rail RL2 extending in the second direction DR2. The stage STG may move in the second direction DR2 through separate moving members on the first rail RL1 and the second rail RL2. Accordingly, the target substrate SUB may also move in the second direction DR2 along the stage STG. The stage STG and the target substrate SUB may move along the second direction DR2 and pass through the inkjet head 100 disposed thereon, so that the ink 90 may be ejected on the upper surface of the target substrate SUB. there is. In the drawings, a structure in which the stage STG moves in the second direction DR2 is shown, but is not limited thereto, and in some embodiments, the inkjet head 100 may move in the second direction DR2. Hereinafter, for convenience of description, the movement of the stage STG in the second direction DR2 through the first rail RL1 and the second rail RL2 will be mainly described.

The inkjet head unit 100 may serve to jet the ink 90 onto the target substrate SUB through the plurality of nozzle units 300 . The plurality of nozzle units 300 may be attached to the lower surface of the inkjet head unit 100 . The plurality of nozzle units 300 are spaced apart from each other on the lower surface of the inkjet head unit 100 and may be arranged in one row or a plurality of rows.

The inkjet head unit 100 is spaced apart from the target substrate SUB seated on the stage STG in the third direction DR3, and the ink 90 is disposed on the upper surface of the target substrate SUB in the third direction DR3. can eject. The inkjet head unit 100 is disposed on the base frame 600 and its position can be adjusted by the configuration of the base frame 600 .

The base frame 600 may serve to mount and move the inkjet head 100 on which the plurality of nozzle units 300 are disposed, and to define a moving path thereof. The base frame 600 may include a support 610 and a moving unit 630 .

The support part 610 of the base frame 600 may include a first support part 611 and a second support part 612 . The first support part 611 may serve to support the inkjet head part 100 in which the plurality of nozzle parts 300 are disposed. In some embodiments, the first support part 611 may have a rod shape extending in the first direction DR1, but is not limited thereto. The second support part 612 may serve to support the first support part 611 in the third direction DR3 . The second support part 612 may be connected to both ends of the first support part 611 in the first direction DR1 and extend in the third direction DR3 . Accordingly, the inkjet head 100 in which the first support part 611 and the plurality of nozzle parts 300 are disposed may be spaced apart from the stage STG in the third direction DR3.

The second support part 612 connected to one side of the first support part 611 in the first direction DR1 and the second support part 612 connected to the other side of the first support part 611 in the first direction DR1 are They may be spaced apart from each other in the direction DR1. The stage STG and the substrate SUB are connected to the second support 612 connected to one side of the first support 611 in the first direction DR1 and the other side of the first support 611 in the first direction DR1. It may be disposed in the spaced apart space between the second support parts 612 to be.

The moving unit 630 of the base frame 600 serves to support the inkjet head 100 on which the plurality of nozzle units 300 are disposed and moves the inkjet head 100 on which the plurality of nozzle units 300 are disposed. It may serve to move in the first direction DR1. The moving unit 630 is mounted on the first support part 611 and has a moving part 631 that can move in the first direction DR1 and a plurality of nozzle parts 300 disposed on the lower surface of the moving part 631. It may include a fixing part 632 on which the inkjet head 100 is disposed. The moving part 631 is disposed on the first support part 611 and can move in the first direction DR1 on the first support part 611, and the inkjet head part 100 in which the plurality of nozzle parts 300 are disposed. is fixed to the fixing part 632 and may move in the first direction DR1 together with the moving part 631 .

The ink storage unit 500 may serve to store ink 90 to be supplied to the inkjet head unit 100 . In some embodiments, the ink storage unit 500 may be disposed on one side of the first support unit 611, but is not limited thereto. The ink reservoir 500 may be connected to the inkjet head 100 through the first connection pipe IL1 and the second connection pipe IL2. The ink 90 in the ink reservoir 500 is supplied to the inkjet head 100 through the first connection pipe IL1, and the remaining ink 90 discharged from the inkjet head 100 is supplied to the second connection pipe. It can be recovered back to the ink storage unit 500 through (IL2).

Specifically, as shown in FIG. 3, the ink reservoir 500 includes a first ink reservoir 510, a second ink reservoir 520, a third ink reservoir 530, a pressure pump 550, A compressor 560 and a flow meter may be included. In this case, in the ink reservoir 500, the second ink reservoir 520, the pressure pump 550, and the third ink reservoir 530 are connected to the inkjet head 100, and these are one circulation system. can form

The first ink storage unit 510 may serve to prepare the manufactured ink 90 . The ink 90 including the solvent 91 and the bipolar element 95 may be prepared in the first ink reservoir 510, and the ink 90 may be supplied to the circulation system.

The second ink reservoir 520 may be connected to the first ink reservoir 510 to supply the prepared ink 90 . In addition, the second ink reservoir 520 may serve as a reservoir in which remaining ink 90 discharged from the inkjet head 100 is recovered through the second connection pipe IL2 . The second ink reservoir 520 may be located between the third ink reservoir 530 , the inkjet head 100 and the first ink reservoir 510 . When the second ink storage unit 520 is located between the third ink storage unit 530, the inkjet head unit 100, and the first ink storage unit 510, an appropriate amount is stored in the third ink storage unit 530. It is possible to smoothly disperse the bipolar element 95 by controlling the supply of the ink 90 . The ink 90 supplied to the second ink reservoir 520 may be supplied to the third ink reservoir 530 through the pressure pump 550 .

The pressure pump 550 may serve to deliver power to the fluid so that the ink 90 in the circulation system can be circulated. A flow meter 580 may be provided between the pressure pump 550 and the third ink reservoir 530, and the flow meter 580 measures the flow rate of the ink 90 supplied to the third ink reservoir 530. can measure The pressure pump 550 may adjust the flow rate of the ink 90 supplied to the third ink reservoir 530 according to the flow rate of the ink 90 measured by the flow meter 580 .

The compressor 560 may serve to adjust pressure in the third ink reservoir 530 . The compressor 560 may remove gas so that the inside of the third ink reservoir 530 is in a vacuum state, or may introduce an external inert gas to have a certain pressure. However, depending on the embodiment, the compressor 560 may be omitted.

The third ink reservoir 530 may supply ink 90 to the inkjet head 100 through the first connection pipe IL1. In some embodiments, the third ink reservoir 530 may include an agitator, and the agitator may disperse the bipolar element 95 in the ink 90 . As the agitator rotates, the ink 90 supplied to the third ink reservoir 530 may maintain a dispersed state without sinking the bipolar elements 95 . That is, the agitator of the third ink reservoir 530 is a pair of bipolar elements 95 sinking in the lower portion of the third ink reservoir 530 and ejecting the ink 90 through the inkjet head 100. A decrease in the number of polar elements 95 can be prevented. Accordingly, the third ink reservoir 530 can supply the ink 90 in which the bipolar element 95 is smoothly dispersed to the inkjet head 100, and the inkjet head 100 has a certain level of bipolarity. Ink 90 including the element 95 may be ejected.

A first valve VA1 and a second valve VA2 may be disposed on the first connection pipe IL1 and the second connection pipe IL2, respectively. Specifically, a first valve VA1 is disposed on the first connection pipe IL1 to control the flow rate of the ink 90 supplied from the first connection pipe IL1 to the inkjet head 100, and the second connection pipe A second valve VA2 is disposed on the IL2 to adjust the flow rate of the ink 90 recovered from the inkjet head 100 to the second connection pipe IL2.

The ink 90 is a solvent 91 and a solid material contained in the solvent 91, and may include a plurality of bipolar elements 95. The ink 90 may be provided in a solution or colloidal state. The bipolar element 95 may include a first end having a first polarity and a second end having a second polarity. The plurality of bipolar elements 95 may be included in a dispersed state in the solvent 91 and supplied to the inkjet head 100 to be ejected.

In some embodiments, the solvent 91 may be acetone, water, alcohol, toluene, propylene glycol (PG) or propylene glycol methyl acetate (PGMA), but is not limited thereto. .

The inkjet printing device 1 may further include a probe device 700 .

The probe device 700 may serve to form an electric field on the target substrate SUB. The probe device 700 may be disposed on the stage STG. The probe device 700 may include a sub-stage 710 supporting the target substrate SUB. In other words, the target substrate SUB may be placed on the sub-stage 710 of the probe device 700 disposed on the stage STG.

After the bipolar elements 95 of the ink 90 have a specific alignment direction and are sprayed on the target substrate SUB, they are aligned in one direction on the target substrate SUB by the electric field generated by the probe device 700. can A detailed description of this will be described later in conjunction with FIGS. 11 to 14 .

Hereinafter, the nozzle unit 300 of the inkjet printing apparatus 1 according to an exemplary embodiment will be described in detail.

FIG. 4 is a perspective view schematically illustrating a nozzle unit and an optical sensor unit of the inkjet printing apparatus according to the embodiment of FIG. 1 . 5 is a perspective view schematically illustrating the nozzle unit of FIG. 4 . 6 is a structural diagram schematically showing the inside of the nozzle unit of FIG. 4 . FIG. 7 is an enlarged view of a region Q1 of FIG. 6 . 8 is a cross-sectional view showing a schematic cross-section taken along the line X1-X1′ of FIG. 4 .

4 to 7, the ink 90 jet printing device 1 according to an embodiment includes an optical sensor unit 400, and the nozzle unit 300 of the ink 90 jet printing device 1 ) may include a base part 310, a supply passage 330a, an excitation part 370, an internal passage 330b, a recovery passage 330c, a plurality of outlets 350, and a light transmission part LA. A plurality of optical sensor units 400 may be disposed to correspond to each of the plurality of outlets 350 .

The nozzle part 300 may define a light transmitting part LA. As shown in FIG. 8 , the light emitting portion LA is an area through which light is transmitted and is visible to the outside, and light may not be visible from the outside because light is blocked in the area other than the light emitting portion LA. As will be described later, the light transmitted from the light emitting unit LA is irradiated to the optical sensor unit 400, and the optical sensor unit 400 determines the intensity of light recognized by the light emitting unit LA of the nozzle unit 300, in other words, The number of bipolar elements 95 dispersed in the ink 90 can be measured by measuring the amount of light.

The light transmitting part LA may be made of a transparent material. In some embodiments, the light transmitting part LA may include glass or quartz, but is not limited thereto. The remaining area of the nozzle unit 300 excluding the light transmitting part LA may include a material that blocks light. In some embodiments, the remaining area of the nozzle unit 300 excluding the light transmitting part LA may include a black pigment, but is not limited thereto.

The base part 310 of the nozzle part 300 may serve to form the base of the nozzle part 300 . A flow passage 330 penetrating the inside of the nozzle unit 300 may be disposed. The flow path 330 may include a supply flow path 330a, an internal flow path 330b, and a return flow path 330c. In other words, the supply passage 330a, the excitation part 370, the internal passage 330b, the recovery passage 330c, and the plurality of outlets 350 may be members disposed inside the base part 310. In other words, the supply passage 330a, the internal passage 330b, the recovery passage 330c, and the plurality of outlets 350 may mean pipes penetrating the inside of the base part 310.

The supply passage 330a of the nozzle unit 300 may serve to introduce the ink 90 supplied from the ink jet head unit into the plurality of discharge ports 350 . In other words, the ink 90 located in the inkjet head 100 may move to the supply passage 330a of the nozzle 300 through an internal tube (not shown) of the inkjet head 100 . A portion of the ink 90 that has moved to the supply passage 330a passes through the internal passage 330b and moves to each of the plurality of discharge units and is ejected, and the rest of the ink 90 passes through the internal passage 330b and is discharged into the recovery passage ( It moves to 330c) and can be recovered to the inkjet head unit 100 again. In some embodiments, the supply passage 330a may extend in the third direction DR3, but is not limited thereto.

An excitation unit 370 may be disposed on the supply passage 330a. The excitation unit 370 may serve to excite the bipolar element 95 dispersed in the solvent 91 so that the bipolar element 95 emits light. Specifically, as shown in FIG. 7 , the excitation unit 370 may irradiate the first light L1 to the bipolar element 95 passing through the supply passage 330a. The bipolar element 95 irradiated with the first light L1 emitted from the excitation unit 370 is excited to emit the second light L2.

In some embodiments, the first light L1 has a wavelength in the ultraviolet region, that is, a wavelength range of 10 nm to 400 nm, and the second light L2 has a visible ray region, that is, a wavelength range of 400 nm to 700 nm. It may be, but is not limited thereto. Hereinafter, for convenience of description, the first light L1 has a wavelength range in the ultraviolet region and the second light L2 has a wavelength range in the visible ray region. In this case, the optical sensor unit 400 only detects light emitted from the excitation unit 370 by detecting only light from the bipolar element 95 by measuring only the visible light region and not measuring other regions. may not

Meanwhile, the direction of the second light L2 emitted from the bipolar element 95 is not limited to a specific direction. For example, the second light L2 may spread in all directions from the bipolar element 95 . In this case, the intensity of the second light L2 may vary in proportion to the number of bipolar elements 95 . A description of this will be given later.

The excitation part 370 is disposed on the supply passage 330a, and since the flow of the ink 90 inside the nozzle part 300 starts from the supply passage 330a, the internal passage 330b, a plurality of discharge ports ( 350) and the bipolar element 95 passing through the recovery passage 330c may be in an excited state. In other words, the bipolar element 95 passing through the internal passage 330b, the plurality of discharge ports 350, and the recovery passage 330c is the second light L2 having a visible ray region, that is, a wavelength range of 400 nm to 700 nm. ) can be released.

Since the excitation part 370 is disposed on the supply passage 330a, it may not overlap the light transmitting area. Accordingly, the optical sensor unit 400 can accurately measure the number of bipolar elements 95 by sensing only the second light L2 without sensing the first light L1 emitted by the excitation unit 370. can

The internal passage 330b of the nozzle unit 300 serves to provide a path for moving the solvent 91 and the bipolar element 95 from the supply passage 330a to the plurality of discharge ports 350 or the recovery passage 330c. can do. In some embodiments, the internal passage 330b may extend in the first direction DR1, but is not limited thereto.

The nozzle unit 300 may define a plurality of discharge ports 350 penetrating the base unit 310 . The solvent 91 and the bipolar element 95 entering the plurality of outlets 350 through the internal passage 330b will be discharged from the plurality of outlets 350 . Each of the plurality of discharge ports 350 may include a first region 350a that does not overlap the light-transmitting region of the nozzle unit 300 and blocks light, and a second region 350b that overlaps the light-transmitting region and transmits light. can

The first region 350a of the discharge port 350 may be a portion directly connected to the internal passage 330b. The first area 350a is an area to shield the second light L2 emitted from the excited bipolar element 95, and as will be described later, the optical sensor unit 400 senses the second light L2. This is an area that cannot be In other words, the first area 350a of the discharge port 350 may not overlap the light transmission area of the nozzle unit 300 in the second direction DR2 .

The second region 350b of the discharge port 350 is an area disposed at the end of the discharge port 350 and may be an area where the ink 90 discharged from the nozzle unit 300 is located. In addition, the second region 350b transmits the second light L2 emitted from the excited bipolar element 95, and as will be described later, the optical sensor unit 400 transmits the second light L2. This is an area that can be sensed. In other words, the second area 350b of the discharge port 350 overlaps the light transmission area of the nozzle unit 300 in the second direction DR2 and overlaps the optical sensor unit 400 in the second direction DR2. can

A volume of the ink 90 located in the second region 350b of the outlet 350 may be the same as a volume of the ink 90 discharged from the outlet 350 . Specifically, the ink 90 located in the second area 350b of the outlet 350 is the same as the ink 90 later ejected from the outlet 350, and is in the second area 350b of the outlet 350. The volume of the solvent 91 of the ink 90 positioned and the number of bipolar elements 95 is the ratio between the volume of the solvent 91 of the ink 90 ejected from the ejection port 350 and the number of bipolar elements 95. may be equal to the number of For example, if the number of bipolar elements 95 dispersed in the ink 90 located in the second region 350b of the discharge port 350 is two, the ink 90 discharged from the discharge port 350 later The number of bipolar elements 95 dispersed in will also be two.

The optical sensor unit 400 may serve to measure the number of bipolar elements 95 inside the ink 90 to be discharged from the discharge port 350 . The optical sensor unit 400 may be disposed adjacent to the transmission portion of the nozzle unit 300 . This may be for accurately measuring the intensity (ie, the amount of light) of the second light L2 emitted from the bipolar element 95 . In some embodiments, the optical sensor unit 400 may be disposed apart from the nozzle unit 300, but is not limited thereto.

The optical sensor unit 400 senses the intensity of the second light L2 emitted from the bipolar element 95, and the pair dispersed in the ink 90 located in the second region 350b of the discharge port 350. The number of polar elements 95 can be measured. For example, when the number of bipolar elements 95 dispersed in the ink 90 located in the second region 350b of the discharge port 350 is two, the second region 350b of the discharge port 350 The intensity of the second light L2 transmitted through may be about twice as high as that of the case where the number of bipolar elements 95 is one. In other words, since the intensity of light transmitted through the second region 350b of the discharge port 350 has a correlation that is substantially proportional to the number of bipolar elements 95, this is used to determine the second area of the discharge port 350. The number of bipolar elements 95 dispersed within region 350b can be measured.

The area of the optical sensor unit 400 may be larger than the area of the second area 350b of the outlet 350 . In other words, the width 400h of the optical sensor unit 400 in the third direction DR3 may be greater than the width of the second area 350b of the outlet 350 in the third direction DR3. Hereinafter, 'area' means a surface area, and means a surface area on the side of the second direction DR2. Specifically, the area of the optical sensor unit 400 means the surface area of the side of the optical sensor unit 400 in the second direction (DR2), and the area of the second region 350b of the outlet 350 is the area of the outlet 350. This refers to the surface area of the side surface of the second region 350b in the second direction DR2, and the area of the light emitting part LA of the nozzle part 300 is the area of the light emitting part LA of the nozzle part 300 in the second direction ( DR2) may mean the surface area of a side. Since the area of the optical sensor unit 400 is larger than the area of the second area 350b of the outlet 350, the optical sensor unit 400 accurately senses the second light L2 passing through the light emitting unit LA. can do. Accordingly, the optical sensor unit 400 may completely cover the second area 350b of the discharge port 350 and overlap a part of the first area 350a.

Meanwhile, since the second area 350b of the discharge hole 350 is defined as an area overlapping the light transmitting part LA, the area of the second area 350b of the discharge hole 350 is equal to the area of the light transmitting part LA. something to do.

The recovery passage 330c of the nozzle unit 300 is a path through which ink 90 passing through the internal passage 330b is returned to the inkjet head 100 except for the ink 90 that moves to the plurality of outlets 350 and is ejected. can play a role in providing In some embodiments, the recovery passage 330c may extend in the third direction DR3, but is not limited thereto.

Meanwhile, the bipolar element 95 may be a light emitting element ED applied on the pixel PX in a display device manufacturing process (see FIGS. 15 to 21 ) to be described later. The light emitting elements ED need to be coated in a uniform number on the pixels PX in terms of a process. If the light emitting device ED is not disposed on the pixel PX, a screen defect may occur. However, depending on factors such as the flow rate, flow velocity, or vortex of the ink 90 flowing inside the nozzle unit 300, the bipolar element 95 discharged from each of the plurality of discharge ports 350 in some cases, that is, the light emitting element ( ED) may vary. Therefore, it is necessary to correct the number of bipolar elements 95 in real time by measuring the number of different bipolar elements 95 in each of the plurality of discharge ports 350 . Hereinafter, a real-time bipolar element 95 replenishment process of the ink 90 jet printing device 1 according to an embodiment will be described.

9 and 10 are diagrams for explaining a real-time replenishment process of the bipolar element 95 of the inkjet printing apparatus 1 according to the embodiment of FIG. 1 .

9 and 10, the optical sensor unit 400 measures the number of bipolar elements 95 in each of the plurality of discharge ports 350, and then the discharge port 350 where the number of bipolar elements 95 is insufficient. ) is selected. Thereafter, the insufficient number of bipolar elements 95 is replenished by additionally discharging ink 90 from the discharge port 350 where the number of bipolar elements 95 is insufficient.

After the optical sensor unit 400 measures the number of bipolar elements 95 in each of the plurality of discharge ports 350, the process of selecting the discharge ports 350 having an insufficient number of bipolar elements 95 is as described above. Similarly, the selection may be performed using the fact that the intensity of the second light L2 transmitted through the light transmitting unit LA varies according to the number of bipolar elements 95 . For example, if one of the plurality of discharge ports 350 lacks the bipolar element 95 and two of the bipolar elements 95 are dispersed in the other discharge ports 350, the pair The intensity of the second light L2 transmitted through the outlet 350 lacking the polarity element 95 may be relatively low compared to the intensity of the second light L2 transmitted through the remaining outlets 350 . The optical sensor unit 400 may measure the intensity of the second light L2 and select the outlet 350 having an insufficient number of bipolar elements 95 .

After selecting the outlet 350 having an insufficient number of bipolar elements 95 , ink 90 may be further discharged from the outlet 350 to supplement the insufficient number of bipolar elements 95 . In this case, the ink 90 may not be discharged from the remaining discharge ports 350 .

Through the configuration and replenishment method as described above, the inkjet printing apparatus 1 according to an embodiment measures the number of bipolar elements 95 dispersed in the ink 90 in the nozzle unit 300 before being ejected, Since there is no need to consider the dynamic state of the ejected ink 90, sensing reliability can be improved, and the number of bipolar elements 95 ejected per plurality of ejection holes 350 can be grasped in real time, so that the bipolar elements 95 ) is easy to supplement, so unnecessary processes can be omitted and fairness can be improved.

Hereinafter, the probe device 700 of the inkjet printing device 1 according to an embodiment will be described.

FIG. 11 is a schematic plan view of the probe device of the inkjet printing apparatus according to the embodiment of FIG. 1 viewed from a third direction. 12 and 13 are schematic diagrams illustrating the operation of the probe device of FIG. 11 . FIG. 14 is a schematic diagram illustrating alignment of solids inside ink by generating an electric field on a target substrate by the probe device of FIG. 11;

Referring to FIGS. 11 to 14 , a probe device 700 may include a sub-stage 710 , a probe support 730 , a probe unit 750 and an aligner 780 .

The probe device 700 is disposed on the stage STG and may move in the second direction DR2 together with the stage STG. The probe device 700 on which the target substrate SUB is disposed moves along the stage STG, and ink 90 may be ejected thereon. When the ink 90 is ejected, the probe device 700 may generate an electric field IEL on the top of the target substrate SUB.

The sub-stage 710 may provide a space in which the target substrate SUB is disposed. Also, a probe support 730 , a probe support 730 , a probe unit 750 , and an aligner 780 may be disposed on the sub-stage 710 .

At least one aligner 780 may be disposed on the sub-stage 710 . The aligners 780 are disposed on each side of the sub-stage 710, and an area surrounded by the plurality of aligners 780 may be an area where the target substrate SUB is disposed.

The probe support 730 and the probe unit 750 may be disposed on the sub-stage 710 . The probe support 730 may provide a space in which the probe unit 750 is disposed on the sub-stage 710 . Specifically, the probe support 730 may be disposed on at least one side of the sub-stage 710 and extend along a direction in which one side is extended. For example, as shown in the drawing, the probe support 730 may be disposed to extend in the second direction DR2 from the left and right sides of the sub-stage 710 .

The probe unit 750 may be disposed on the probe support 730 to form an electric field on the target substrate SUB prepared on the sub-stage 710 . Like the probe support 730, the probe unit 750 extends in the second direction DR2, and the extended length may cover the entire target substrate SUB.

The probe unit 750 is connected to a probe driving unit 753 disposed on the probe support 730, a probe jig 751 disposed on the probe driving unit 753 to which electrical signals are transmitted, and the probe jig 751. A probe pad 758 may be included to transfer the electrical signal to the target substrate SUB.

The probe driver 753 may be disposed on the probe support 730 to move the probe jig 751 and the probe pad 758 in the third direction DR3. The probe pad 758 may be connected to or separated from the target substrate SUB by driving the probe driver 753 .

As shown in FIG. 13 , the probe pad 758 may be connected to the target substrate SUB to form an electric field IEL on the target substrate SUB through an electrical signal transmitted from the probe jig 751 . For example, the probe pad 758 may contact an electrode or power pad of the target substrate SUB, and an electric signal of the probe jig 751 may be transferred to the electrode or power pad.

The probe jig 751 may be connected to the probe pad 758 and may be connected to a separate voltage application device. The probe jig 751 may transfer the electric signal transmitted from the voltage applying device to the probe pad 758 to form an electric field IEL on the target substrate SUB. The electric signal transmitted to the probe jig 751 may be a voltage for forming the electric field IEL, for example, an AC voltage. The number of probe jigs 751 may be plural, and the number is not limited.

As described above, in the ink 90 discharged from the nozzle unit 300 onto the target substrate SUB, the bipolar element 95 including the first end and the second end having polarity may be dispersed. When the bipolar element 95 is subjected to a predetermined electric field, a dielectrophoretic force is transmitted so that the position or orientation direction may change. The positions and alignment directions of the plurality of bipolar elements 95 in the ink 90 sprayed on the target substrate SUB are changed by the electric field IEL generated by the probe device 700 as shown in FIG. 14 . can be seated on the target substrate (SUB) while

Meanwhile, the timing at which the probe device 700 generates the electric field IEL on the target substrate SUB is not particularly limited. The figure shows that the probe unit 750 generates the electric field IEL while the ink 90 is ejected from the nozzle unit 300 and reaches the target substrate SUB. Accordingly, the bipolar element 95 may receive dielectrophoretic force by the electric field IEL until it is discharged from the nozzle and reaches the target substrate SUB. In some embodiments, the probe unit 750 may generate an electric field IEL after the ink 90 is deposited on the target substrate SUB.

Meanwhile, although not shown in the drawing, the inkjet printing apparatus 1 according to an embodiment may further include a heat treatment unit in which a process of volatilizing the ink 90 sprayed on the target substrate SUB is performed. The heat treatment unit irradiates heat to the ink 90 sprayed on the target substrate SUB, the solvent 91 of the ink 90 is volatilized and removed, and the bipolar element 95 is applied on the target substrate SUB. can be placed in Since the process of removing the solvent 91 by irradiating heat to the ink 90 may be performed as a conventional heat treatment process, a detailed description thereof will be omitted.

Meanwhile, the above-described bipolar element 95 may be a light emitting element 30 including a plurality of semiconductor layers, and the inkjet printing device 1 according to an embodiment is a display device including the light emitting element 30. (DD) can be prepared. Hereinafter, the display device DD including the light emitting element 30 will be described.

15 is a schematic plan view of a display device according to an exemplary embodiment. FIG. 16 is a layout diagram schematically illustrating the structure of one pixel of the display device according to the exemplary embodiment of FIG. 15 . 17 is a schematic diagram of a light emitting element of the display device according to the exemplary embodiment of FIG. 15 . 18 is a cross-sectional view taken along lines Xa-Xa′, Xb-Xb′, and Xc-Xc′ of FIG. 16 . 19 to 21 are schematic diagrams illustrating a manufacturing method of the display device according to the exemplary embodiment of FIG. 15 .

Referring to FIG. 15 , the display device DD according to an exemplary embodiment displays a moving image or a still image. The display device DD may refer to any electronic device providing a display screen. For example, televisions, laptops, monitors, billboards, Internet of Things, mobile phones, smart phones, tablet PCs (Personal Computers), electronic watches, smart watches, watch phones, head-mounted displays, mobile communication terminals, An electronic notebook, an electronic book, a portable multimedia player (PMP), a navigation device, a game machine, a digital camera, a camcorder, and the like may be included in the display device DD.

The shape of the display device DD may be variously modified. For example, the display device DD may have a shape such as a horizontally long rectangle, a vertically long rectangle, a square, a rectangle with rounded corners, other polygons, or a circle. The shape of the display area DA of the display device DD may also be similar to the overall shape of the display device DD. In FIG. 13 , a display device DD and a display area DA having a horizontally long rectangular shape are illustrated.

The display device DD may include a display area DA and a non-display area NDA. The display area DA is an area where the screen can be displayed, and the non-display area NDA is an area where the screen is not displayed. The display area DA may be referred to as an active area, and the non-display area NDA may also be referred to as a non-active area.

The display area DA may generally occupy the center of the display device DD. The display area DA may include a plurality of pixels. A plurality of pixels may be arranged in a matrix direction. The shape of each pixel may be a rectangle or a square on a plane, but is not limited thereto and may be a rhombus shape with each side inclined in one direction. Each of the pixels may display a specific color by including one or more light emitting elements 30 emitting light of a specific wavelength range.

Referring to FIG. 16 , each of the plurality of pixels PX may include a first sub-pixel PX1 , a second sub-pixel PX2 , and a third sub-pixel PX3 . The first sub-pixel PX1 emits light of a first color, the second sub-pixel PX2 emits light of a second color, and the third sub-pixel PX3 emits light of a third color. can The first color may be blue, the second color may be green, and the third color may be red, but is not limited thereto, and each sub-pixel PXn may emit light of the same color. In addition, although FIG. 30 illustrates that the pixel PX includes three sub-pixels PXn, it is not limited thereto, and the pixel PX may include a larger number of sub-pixels PXn.

Each sub-pixel PXn of the display device DD may include an area defined as an emission area EMA. The first sub-pixel PX1 emits the first emission region EMA1, the second sub-pixel PX2 emits the second emission region EMA2, and the third sub-pixel PX3 emits the third emission region EMA2. can include The light emitting area EMA may be defined as an area where the light emitting element 30 included in the display device DD is disposed to emit light of a specific wavelength range.

Although not shown in the drawing, each sub-pixel PXn of the display device DD may include a non-emission area defined as an area other than the emission area EMA. The non-emission area may be an area in which the light emitting element 30 is not disposed and light emitted from the light emitting element 30 does not reach and no light is emitted.

Each sub-pixel PXn of the display device DD includes a plurality of electrodes 21 and 22, a light emitting element 30, a plurality of contact electrodes 26, and a plurality of internal banks 41 and 42 (shown in FIG. 15). An external bank 43 and at least one insulating layer 51, 52, 53, 55 (shown in FIG. 15) may be included.

The plurality of electrodes 21 and 22 are electrically connected to the light emitting elements 30, and a predetermined voltage may be applied so that the light emitting element 30 emits light of a specific wavelength range. In addition, at least a portion of each of the electrodes 21 and 22 may be used to form an electric field in the sub-pixel PXn to align the light emitting element 30 .

The plurality of electrodes 21 and 22 may include a first electrode 21 and a second electrode 22 . In an exemplary embodiment, the first electrode 21 may be a pixel electrode separated for each sub-pixel PXn, and the second electrode 22 may be a common electrode commonly connected along each sub-pixel PXn. One of the first electrode 21 and the second electrode 22 may be an anode electrode of the light emitting element 30 , and the other may be a cathode electrode of the light emitting element 30 . However, it is not limited thereto and may be vice versa.

The first electrode 21 and the second electrode 22 extend in the vertical direction, which is a direction crossing the horizontal direction, in the electrode stems 21S and 22S and the electrode stems 21S and 22S, respectively, extending in the horizontal direction. It may include at least one electrode branch portion 21B or 22B extending and branching.

The first electrode 21 includes a first electrode stem 21S extending in a horizontal direction and at least one first electrode branch 21B branched from the first electrode stem 21S and extending in a vertical direction. can include

Both ends of the first electrode stem 21S of one arbitrary pixel are spaced apart between each sub-pixel PXn, but the first electrode rows of neighboring sub-pixels in the same row (eg, adjacent in the horizontal direction) It may be substantially collinear with the base 21S. Since both ends of the first electrode stems 21S disposed in each sub-pixel PXn are spaced apart from each other, different electrical signals may be applied to each first electrode branch 21B, and the first electrode branch ( 21B) can be driven separately.

The first electrode branch 21B is branched from at least a part of the first electrode stem 21S and extended in the vertical direction, and the second electrode stem is disposed to face the first electrode stem 21S ( 22S) and can be terminated in a distanced state.

The second electrode 22 extends in the horizontal direction, is spaced apart from the first electrode stem 21S in the vertical direction, and is branched from the second electrode stem 22S and the second electrode stem 22S facing each other in the vertical direction. It may include a second electrode branch portion 22B extending to . The other end of the second electrode stem 22S may be connected to the second electrode stem 22S of another sub-pixel PXn adjacent in the horizontal direction. That is, unlike the first electrode stem 21S, the second electrode stem 22S may be disposed to extend in a horizontal direction and cross each sub-pixel PXn. The second electrode stem 22S crossing each sub-pixel PXn is formed on the outer part of the display area DA or the non-display area NDA where each pixel PX or sub-pixel PXn is disposed. It may be connected to a portion extending in the direction.

The second electrode branch 22B may face and be spaced apart from the first electrode branch 21B, and may terminate while being spaced apart from the first electrode stem 21S. The second electrode branch 22B is connected to the second electrode stem 22S, and an extended end portion may be disposed in the sub-pixel PXn while being spaced apart from the first electrode stem 21S. .

The first electrode 21 and the second electrode 22 are electrically connected to the circuit element layer of the display device DD through contact holes, for example, the first electrode contact hole CNTD and the second electrode contact hole CNTS, respectively. can be connected In the drawing, the first electrode contact hole CNTD is formed in each first electrode stem 21S of each sub-pixel PXn, and the second electrode contact hole CNTS is formed across each sub-pixel PXn. It is shown that only one is formed on the second electrode stem portion 22S. However, it is not limited thereto, and in some cases, the second electrode contact hole CNTS may be formed for each sub-pixel PXn.

The external bank 43 is disposed on the boundary between each sub-pixel PXn, and the plurality of internal banks 41 and 42 are adjacent to the center of each sub-pixel PXn and disposed below each electrode 21 and 22. can Although the plurality of inner banks 41 and 42 are not shown in the drawing, the first inner bank 41 and the second inner bank 42 are located below the first electrode branch 21B and the second electrode branch 22B, respectively. ) can be placed.

The external bank 43 may be disposed at a boundary between each sub-pixel PXn. Each end of the plurality of first electrode stem portions 21S may terminate with being spaced apart from each other with respect to the external bank 43 . The external bank 43 may extend in a vertical direction and may be disposed at a boundary of sub-pixels PXn arranged in a horizontal direction. However, the present invention is not limited thereto, and the external bank 43 extends in the horizontal direction and may be disposed at the boundary of the sub-pixels PXn arranged in the vertical direction. The outer bank 43 may be formed simultaneously in one process by including the same material as the inner banks 41 and 42 .

The light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22 . The light emitting element 30 may have one end electrically connected to the first electrode 21 and the other end electrically connected to the second electrode 22 . The light emitting element 30 may be electrically connected to the first electrode 21 and the second electrode 22 through contact electrodes 26 to be described later.

The plurality of light emitting devices 30 may be spaced apart from each other and aligned substantially parallel to each other. The interval at which the light emitting elements 30 are separated is not particularly limited. In some cases, a plurality of light emitting elements 30 are arranged adjacently to form a group, and a plurality of other light emitting elements 30 may form a group at a predetermined interval, and have an uneven density but are oriented in one direction. may be sorted. In addition, in an exemplary embodiment, the light emitting element 30 has a shape extending in one direction, and each electrode, for example, the first electrode branch 21B and the second electrode branch 22B extends along the direction and the light emitting element. The direction in which 30 is extended may be substantially vertical. However, it is not limited thereto, and the light emitting element 30 may be disposed obliquely rather than perpendicular to the direction in which the first electrode branch 21B and the second electrode branch 22B extend.

The light emitting element 30 may be a light emitting diode, and specifically, the light emitting element 30 has a size of a micrometer or nanometer unit and is made of an inorganic material. It may be a light emitting diode. In the inorganic light emitting diode, when an electric field is formed in a specific direction between two opposing electrodes, a polarity may be formed between the two electrodes. The light emitting element 30 may be aligned between the electrodes by an electric field formed on the two electrodes.

The light emitting device 30 according to one embodiment may have a shape extending in one direction. The light emitting device 30 may have a shape such as a rod, a wire, or a tube. In an exemplary embodiment, the light emitting element 30 may be cylindrical or rod-shaped. However, the shape of the light emitting element 30 is not limited thereto, and has a shape of a polygonal column such as a regular hexahedron, a rectangular parallelepiped, a hexagonal column, or a light emitting element extending in one direction but having a partially inclined outer surface, etc. ( 30) can have various forms. A plurality of semiconductors included in the light emitting device 30 to be described below may have a structure in which they are sequentially arranged or stacked along one direction.

The light emitting device 30 may include a semiconductor layer doped with any conductivity type (eg, p-type or n-type) impurity. The semiconductor layer may emit light of a specific wavelength range by passing an electric signal applied from an external power source.

Referring to FIG. 17 , the light emitting device 30 may include a first semiconductor layer 31 , a second semiconductor layer 32 , an active layer 36 , an electrode layer 37 and an insulating layer 38 .

The first semiconductor layer 31 may be an n-type semiconductor. For example, when the light emitting device 30 emits light in a blue wavelength band, the first semiconductor layer 31 is AlxGayIn1-x-yN (0≤x≤1,0≤y≤1, 0≤x+y≤ 1) may include a semiconductor material having a chemical formula. For example, it may be any one or more of n-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The first semiconductor layer 31 may be doped with an n-type dopant, and for example, the n-type dopant may be Si, Ge, or Sn. In an exemplary embodiment, the first semiconductor layer 31 may be n-GaN doped with n-type Si. The length of the first semiconductor layer 31 may have a range of 1.5 μm to 5 μm, but is not limited thereto.

The second semiconductor layer 32 is disposed on the active layer 36 to be described later. The second semiconductor layer 32 may be a p-type semiconductor, and for example, when the light emitting device 30 emits light in a blue or green wavelength band, the second semiconductor layer 32 is AlxGayIn1-x-yN (0≤ It may include a semiconductor material having a chemical formula of x≤1,0≤y≤1, 0≤x+y≤1). For example, it may be any one or more of p-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The second semiconductor layer 32 may be doped with a p-type dopant, and for example, the p-type dopant may be Mg, Zn, Ca, Se, Ba, or the like. In an exemplary embodiment, the second semiconductor layer 32 may be p-GaN doped with p-type Mg. The length of the second semiconductor layer 32 may have a range of 0.05 μm to 0.10 μm, but is not limited thereto.

The active layer 36 is disposed between the first semiconductor layer 31 and the second semiconductor layer 32 . The active layer 36 may include a material having a single or multi-quantum well structure. When the active layer 36 includes a material having a multi-quantum well structure, it may have a structure in which a plurality of quantum layers and well layers are alternately stacked. The active layer 36 may emit light by combining electron-hole pairs according to electrical signals applied through the first semiconductor layer 31 and the second semiconductor layer 32 . For example, when the active layer 36 emits light in a blue wavelength range, materials such as AlGaN and AlGaInN may be included. In particular, when the active layer 36 has a multi-quantum well structure in which quantum layers and well layers are alternately stacked, the quantum layer may include AlGaN or AlGaInN, and the well layer may include GaN or AlInN. In an exemplary embodiment, the active layer 36 includes AlGaInN as a quantum layer and AlInN as a well layer. As described above, the active layer 36 includes blue light having a central wavelength range of 450 nm to 495 nm. It may release, but is not limited thereto. For example, the active layer 35 may emit light in red and green wavelength bands depending on the case by including group 3 to 5 semiconductor materials according to the wavelength band of emitted light. The length of the active layer 36 may have a range of 0.05 μm to 0.10 μm, but is not limited thereto.

Meanwhile, light emitted from the active layer 36 may be emitted not only to the outer surface of the light emitting device 30 in the longitudinal direction, but also to both side surfaces. The direction of light emitted from the active layer 36 is not limited to one direction.

The electrode layer 37 may be an Ohmic contact electrode. However, it is not limited thereto, and may be a Schottky contact electrode. The light emitting element 30 may include at least one electrode layer 37 . 17 shows that the light emitting element 30 includes one electrode layer 37, but is not limited thereto. In some cases, the light emitting element 30 may include a larger number of electrode layers 37 or may be omitted. Description of the light emitting element 30 to be described later may be applied in the same way even if the number of electrode layers 37 is different or other structures are further included.

The electrode layer 37 may reduce resistance between the light emitting element 30 and the electrode or contact electrode when the light emitting element 30 is electrically connected to the electrode or contact electrode in the display device DD according to an exemplary embodiment. . The electrode layer 37 may include a conductive metal. For example, the electrode layer 37 may include aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO), and ITZO ( Indium Tin-Zinc Oxide) may include at least one. In addition, the electrode layer 37 may include a semiconductor material doped with n-type or p-type. The electrode layer 37 may include the same material or may include different materials, but is not limited thereto.

The insulating film 38 is disposed to surround outer surfaces of the plurality of semiconductor layers and electrode layers described above. In an exemplary embodiment, the insulating film 38 is disposed to surround at least an outer surface of the active layer 36 and may extend in one direction in which the light emitting element 30 extends. The insulating film 38 may serve to protect the members. For example, the insulating film 38 may be formed to surround the side surfaces of the members, and both ends of the light emitting element 30 in the longitudinal direction may be exposed.

Although the figure shows that the insulating film 38 extends in the longitudinal direction of the light emitting element 30 and is formed to cover from the first semiconductor layer 31 to the side surface of the electrode layer 37, it is not limited thereto. The insulating film 38 may cover only the outer surface of a portion of the semiconductor layer including the active layer 36 or cover only a portion of the outer surface of the electrode layer 37 so that the outer surface of each electrode layer 37 may be partially exposed. In addition, the insulating film 38 may be formed to have a rounded upper surface in cross section in a region adjacent to at least one end of the light emitting element 30 .

A thickness of the insulating layer 38 may range from 10 nm to 1.0 μm, but is not limited thereto. Preferably, the thickness of the insulating film 38 may be about 40 nm.

The insulating film 38 is made of materials having insulating properties, for example, silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum nitride (AlN), It may include aluminum oxide (Al2O3) and the like. Accordingly, an electrical short circuit that may occur when the active layer 36 directly contacts an electrode through which an electrical signal is transmitted to the light emitting element 30 can be prevented. In addition, since the insulating film 38 protects the outer surface of the light emitting element 30 including the active layer 36, it is possible to prevent a decrease in light emitting efficiency.

Also, in some embodiments, the outer surface of the insulating layer 38 may be surface-treated. When manufacturing the display device DD, the light emitting element 30 may be sprayed and aligned on the electrode in a dispersed state in a predetermined ink 90 . Here, in order to keep the light emitting element 30 dispersed within the ink 90 without being aggregated with other adjacent light emitting elements 30 , the surface of the insulating film 38 may be treated to make it hydrophobic or hydrophilic.

The light emitting device 30 may have a length h in the range of 1 μm to 10 μm or 2 μm to 6 μm, preferably 3 μm to 5 μm. In addition, the diameter of the light emitting device 30 may have a range of 30 nm to 700 nm, and an aspect ratio of the light emitting device 30 may be 1.2 to 100. However, it is not limited thereto, and the plurality of light emitting devices 30 included in the display device DD may have different diameters depending on the difference in composition of the active layer 36 . Preferably, the diameter of the light emitting device 30 may have a range of about 500 nm.

The light emitting device 30 according to an embodiment may emit light of different wavelengths to the outside by including the active layer 36 including different materials. In the display device DD, the light emitting element 30 of the first sub-pixel PX1 emits first light having a first wavelength in the center wavelength band, and the light emitting element 30 of the second sub-pixel PX2 emits light having a first wavelength in the center wavelength band. Second light having a second wavelength band may be emitted, and the light emitting device 30 of the third sub-pixel PX3 may emit third light having a third wavelength having a central wavelength band. Accordingly, first light may be emitted from the first sub-pixel PX1 , second light may be emitted from the second sub-pixel PX2 , and third light may be emitted from the third sub-pixel PX3 . In some embodiments, the first light is blue light having a central wavelength range of 450 nm to 495 nm, the second light is green light having a central wavelength range of 495 nm to 570 nm, and the third light has a central wavelength range of 620 nm red light ranging from 750 nm to 750 nm. However, it is not limited thereto.

Referring to FIG. 18 , although only the cross-section of the first sub-pixel PX1 is shown in FIG. 18 , the same may be applied to other pixels PX or sub-pixels PXn. 18 illustrates a cross section crossing one end and the other end of the light emitting element 30 disposed in the first sub-pixel PX1.

Meanwhile, although not shown in FIG. 18 , the display device DD may further include a circuit element layer positioned under each of the electrodes 21 and 22 . The circuit element layer may include a plurality of semiconductor layers and a plurality of conductive patterns, and may include at least one transistor and power wiring. However, a detailed description thereof will be omitted below.

16 and 18 , the display device DD may include a first insulating layer 20, electrodes 21 and 22 disposed on the first insulating layer 20, and a light emitting element 30. can A circuit element layer (not shown) may be further disposed under the first insulating layer 20 . The first insulating layer 20 may include an organic insulating material to perform a surface planarization function.

A plurality of inner banks 41 and 42 , an outer bank 43 , a plurality of electrodes 21 and 22 , and a light emitting element 30 may be disposed on the first insulating layer 20 .

When the external bank 43 ejects the ink 90 dispersed by the light emitting element 30 using the inkjet printing device 1 of FIG. 1 when manufacturing the display device DD, the ink 90 A function of preventing crossing of the boundary of the sub-pixel PXn may be performed. The external bank 43 may separate the ink 90 in which different light emitting devices 30 are dispersed for each different sub-pixel PXn so that they are not mixed with each other. However, it is not limited thereto.

The plurality of inner banks 41 and 42 may include a first inner bank 41 and a second inner bank 42 disposed adjacent to the center of each sub-pixel PXn.

The first inner bank 41 and the second inner bank 42 are spaced apart from each other and disposed to face each other. The first electrode 21 may be disposed on the first inner bank 41 and the second electrode 22 may be disposed on the second inner bank 42 . Referring to FIGS. 16 and 18 , it can be understood that the first electrode branch 21B is disposed on the first inner bank 41 and the second electrode branch 22B is disposed on the second inner bank 42. .

The first inner bank 41 and the second inner bank 42 may be disposed to extend in the vertical direction within each sub-pixel PXn. However, the present invention is not limited thereto, and the first internal bank 41 and the second internal bank 42 may be arranged for each sub-pixel PXn to form a pattern on the entire surface of the display device DD. The plurality of inner banks 41 and 42 and the outer bank 43 may include polyimide (PI), but are not limited thereto.

The first inner bank 41 and the second inner bank 42 may have a structure in which at least a portion protrudes from the first insulating layer 20 . The first inner bank 41 and the second inner bank 42 may protrude upward relative to the plane on which the light emitting device 30 is disposed, and at least a portion of the protruding portion may have an inclination. Since the inner banks 41 and 42 protrude from the first insulating layer 20 and have inclined sides, the light emitted from the light emitting device 30 is reflected from the inclined sides of the inner banks 41 and 42. It can be. As will be described later, when the electrodes 21 and 22 disposed on the inner banks 41 and 42 include a material with high reflectivity, light emitted from the light emitting element 30 is reflected from the electrodes 21 and 22 and may proceed in an upper direction of the first insulating layer 20 .

The outer bank 43 is disposed at the boundary of each sub-pixel PXn to form a lattice pattern, but the inner banks 41 and 42 are disposed within each sub-pixel PXn and extend in one direction. .

The plurality of electrodes 21 and 22 may be disposed on the first insulating layer 20 and the internal banks 41 and 42 . As described above, each of the electrodes 21 and 22 includes electrode stem portions 21S and 22S and electrode branch portions 21B and 22B.

The first electrode 21 and the second electrode 22 are partially disposed on the first insulating layer 20 and partially disposed on the first inner bank 41 and the second inner bank 42 It can be. As described above, the first electrode stem portion 21S of the first electrode 21 and the second electrode stem portion 22S of the second electrode 22 extend in the transverse direction, and the first inner bank 41 and the second internal bank 42 may extend in the vertical direction and may also be disposed in a sub-pixel PXn adjacent in the vertical direction.

A first electrode contact hole (CNTD) may be formed in the first electrode stem portion 21S of the first electrode 21 to penetrate the first insulating layer 20 and expose a portion of the circuit element layer. The first electrode 21 may be electrically connected to the transistor of the circuit element layer through the first electrode contact hole CNTD. A predetermined electrical signal may be transferred from the transistor to the first electrode 21 .

The second electrode stem 22S of the second electrode 22 extends in one direction and may be disposed even in a non-emission area where the light emitting elements 30 are not disposed. A second electrode contact hole CNTS may be formed in the second electrode stem portion 22S to expose a portion of the circuit element layer through the first insulating layer 20 . The second electrode 22 may be electrically connected to the power electrode through the second electrode contact hole CNTS. A predetermined electrical signal may be transferred from the power electrode to the second electrode 22 .

Partial regions of the first electrode 21 and the second electrode 22, for example, the first electrode branch 21B and the second electrode branch 22B, respectively, the first inner bank 41 and the second inner bank ( 42) can be placed on. A plurality of light emitting elements 30 are provided in the area between the first electrode 21 and the second electrode 22, that is, in the space where the first electrode branch 21B and the second electrode branch 22B are separated from each other and face each other. can be placed.

Each of the electrodes 21 and 22 may include a transparent conductive material. For example, each of the electrodes 21 and 22 may include a material such as indium tin oxide (ITO), indium zinc oxide (IZO), or indium tin-zinc oxide (ITZO), but is not limited thereto. In some embodiments, each of the electrodes 21 and 22 may include a conductive material having high reflectivity. For example, each of the electrodes 21 and 22 may include a metal such as silver (Ag), copper (Cu), or aluminum (Al) as a material having high reflectivity. In this case, the light incident on the electrodes 21 and 22 may be reflected and emitted in an upper direction of each sub-pixel PXn.

In addition, the electrodes 21 and 22 may have a structure in which a transparent conductive material and a metal layer having high reflectance are stacked one or more layers, or may be formed as one layer including these. In an exemplary embodiment, each of the electrodes 21 and 22 has a stacked structure of ITO/silver (Ag)/ITO/IZO, or an alloy containing aluminum (Al), nickel (Ni), lanthanum (La), or the like. can be However, it is not limited thereto.

The second insulating layer 52 is disposed on the first insulating layer 20 , the first electrode 21 and the second electrode 22 . The second insulating layer 52 is disposed to partially cover the first electrode 21 and the second electrode 22 . The second insulating layer 52 is disposed to cover most of the upper surfaces of the first electrode 21 and the second electrode 22, but may expose portions of the first electrode 21 and the second electrode 22. . The second insulating layer 52 is part of the upper surfaces of the first electrode 21 and the second electrode 22, for example, the upper surface of the first electrode branch 21B disposed on the first inner bank 41 and the second insulating layer 52. Part of the top surface of the second electrode branch 22B disposed on the second inner bank 42 may be exposed. That is, the second insulating layer 52 may be substantially formed on the entire surface of the first insulating layer 20 and may include an opening partially exposing the first electrode 21 and the second electrode 22 . .

The second insulating layer 52 may protect the first electrode 21 and the second electrode 22 and at the same time insulate them from each other. In addition, the light emitting element 30 disposed on the second insulating layer 52 may be prevented from being damaged by direct contact with other members. However, the shape and structure of the second insulating layer 52 is not limited thereto.

The light emitting element 30 may be disposed on the second insulating layer 52 between the respective electrodes 21 and 22 . Illustratively, at least one light emitting element 30 may be disposed on the second insulating layer 52 disposed between each of the electrode branch portions 21B and 22B. However, it is not limited thereto, and although not shown in the drawing, at least some of the light emitting elements 30 disposed in each sub-pixel PXn may be disposed in an area other than between the respective electrode branch portions 21B and 22B. In the light emitting element 30, the first electrode branch 21B and the second electrode branch 22B are disposed on opposite ends and electrically connect to the electrodes 21 and 22 through the contact electrode 26. can be connected

A plurality of layers of the light emitting device 30 may be disposed in a direction horizontal to the first insulating layer 20 . The light emitting element 30 of the display device DD according to an exemplary embodiment may have a shape extending in one direction and may have a structure in which a plurality of semiconductor layers are sequentially disposed in one direction. As described above, in the light emitting element 30, the first semiconductor layer 31, the active layer 36, the second semiconductor layer 32, and the electrode layer 37 are sequentially disposed along one direction, and their outer surfaces are An insulating film 38 may surround it. The light emitting element 30 disposed in the display device DD is disposed such that one direction in which it extends is parallel to the first insulating layer 20, and the plurality of semiconductor layers included in the light emitting element 30 are disposed in the first insulating layer ( 20) may be sequentially arranged along a direction parallel to the upper surface, but is not limited thereto.

In addition, one end of the light emitting element 30 may contact the first contact electrode 26a and the other end may contact the second contact electrode 26b. According to one embodiment, since the insulating film 38 is not formed on the end surface of the light emitting element 30 extending in one direction and is exposed, the first contact electrode 26a and the second contact electrode 26a described later will be provided in the exposed region. It may contact the electrode 26b, but is not limited thereto.

The third insulating layer 53 may be partially disposed on the light emitting element 30 disposed between the first electrode 21 and the second electrode 22 . The third insulating layer 53 may be disposed to partially cover the outer surface of the light emitting device 30 . The third insulating layer 53 may protect the light emitting element 30 and simultaneously fix the light emitting element 30 in the manufacturing process of the display device DD.

The third insulating layer 53 may be disposed to extend in a vertical direction between the first electrode branch 21B and the second electrode branch 22B on a plane. For example, the third insulating layer 53 may have an island shape or a linear shape on a plane on the first insulating layer 20 . According to one embodiment, the third insulating layer 53 may be disposed on the light emitting device 30 .

The first contact electrode 26a and the second contact electrode 26b are disposed on the electrodes 21 and 22 and the third insulating layer 53, respectively. The first contact electrode 26a and the second contact electrode 26b may be spaced apart from each other on the third insulating layer 53 . The third insulating layer 53 may insulate each other so that the first contact electrode 26a and the second contact electrode 26b do not directly contact each other.

The first contact electrode 26a may contact an exposed portion of the first electrode 21 on the first inner bank 41, and the second contact electrode 26b may contact the second inner bank 42. It may contact the exposed partial area of the second electrode 22 . The first contact electrode 26a and the second contact electrode 26b may transmit electric signals transmitted from the respective electrodes 21 and 22 to the light emitting element 30 .

The contact electrode 26 may include a conductive material. For example, it may include ITO, IZO, ITZO, aluminum (Al), and the like. However, it is not limited thereto.

The passivation layer 55 may be disposed on the contact electrode 26 and the third insulating layer 53 . The passivation layer 55 may serve to protect members disposed on the first insulating layer 20 against external environments.

Each of the above-described second insulating layer 52, third insulating layer 53, and passivation layer 55 may include an inorganic insulating material or an organic insulating material. In an exemplary embodiment, the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 are made of silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide ( It may include an inorganic insulating material such as Al2O3), aluminum nitride (AlN), and the like. In addition, the second insulating layer 52, the third insulating layer 53, and the passivation layer 55 are organic insulating materials, acrylic resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin , polyphenylene resin, polyphenylene sulfide resin, benzocyclobutene, cardo resin, siloxane resin, silsesquioxane resin, polymethyl methacrylate, polycarbonate, polymethyl methacrylate-polycarbonate synthetic resin, etc. can However, it is not limited thereto.

Referring to FIGS. 19 to 21 , the display device DD according to an exemplary embodiment may be manufactured using the inkjet printing device 1 described above with reference to FIG. 1 . The inkjet printing device 1 may eject the ink 90 in which the light emitting element 30 is dispersed, and the light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22 of the display device DD. ) can be placed.

First, as shown in FIG. 19, the first insulating layer 20, the first inner bank 41 and the second inner bank 42 disposed spaced apart from each other on the first insulating layer 20, the first The first electrode 21 and the second electrode 22 disposed on the inner bank 41 and the second inner bank 42, respectively, and the second electrode covering the first electrode 21 and the second electrode 22 An insulating material layer 52' is prepared. The second insulating material layer 52 ′ may be partially patterned in a subsequent process to form the second insulating layer 52 of the display device DD. The members may be formed by patterning a metal, inorganic material, or organic material through a conventional mask process.

Next, the ink 90 in which the light emitting element 30 is dispersed is injected onto the first electrode 21 and the second electrode 22 . The light emitting element 30 is a kind of bipolar element 95, and the jetting of the ink 90 in which the light emitting element 30 is dispersed uses the above-described inkjet printing device 1 and the printing method of the bipolar element 95. It can be done using As shown in the figure, the inkjet printing apparatus 1 according to an embodiment may eject the ink 90 while maintaining a uniform number of light emitting elements 30 in the ink 90 . Since a description thereof is the same as described above, a detailed description thereof will be omitted.

Next, as shown in FIG. 20, an electric field (IEL) is generated in the ink 90 in which the light emitting element 30 is dispersed by applying an electric signal to the first electrode 21 and the second electrode 22. . The light emitting element 30 may be seated between the first electrode 21 and the second electrode 22 while the dielectrophoretic force is transmitted by the electric field IEL and the alignment direction and position are changed.

Subsequently, as shown in FIG. 21, the solvent 91 of the ink 90 is removed. Through the above process, the light emitting element 30 may be disposed between the first electrode 21 and the second electrode 22 . Subsequently, although not shown in the drawing, the second insulating material layer 52' is patterned to form the second insulating layer 52, and the third insulating layer 53, the first contact electrode 26a and the second contact electrode ( 26b), and the passivation layer 55 may be formed to manufacture a display device.

Hereinafter, another embodiment of the inkjet printing device 1 according to an embodiment will be described. In the following embodiments, the same reference numerals refer to components identical to those of the previously described embodiments, and redundant descriptions will be omitted or simplified, and description will focus on differences.

22 is a structural diagram schematically illustrating the inside of a nozzle unit of an inkjet printing apparatus according to another embodiment.

Referring to FIG. 22 , in the inkjet printing apparatus 1_1 according to the present embodiment, an excitation unit 371 may be disposed on the first area 350a of each of the plurality of discharge ports 350 . Specifically, a plurality of excitation units 371 may be disposed to correspond to the first regions 350a of each of the plurality of discharge ports 350 .

As the excitation unit 371 is disposed on the first region 350a of each of the plurality of discharge ports 350, the bipolar element 95 in the nozzle unit 301 can be excited only within the discharge port 350, but this It is not limited.

When the excitation unit 371 is disposed on the first region 350a of each of the plurality of discharge ports 350, the duration of the excitation state of the bipolar element 95 does not need to be considered, so that the second light L2 can be generated more accurately. intensity can be measured. For example, the bipolar element 95 emits the second light L2 for a predetermined time after being excited, and the intensity of the emitted second light L2 may gradually weaken over time, so that the optical Although it may be difficult for the sensor unit 400 to accurately measure the intensity of the second light L2, if the excitation unit 371 is disposed on the first area 350a of each of the plurality of discharge ports 350, each discharge port ( 350), since the duration of the excited state of the bipolar element 95 will be substantially the same, the intensity of the second light L2 can be measured more accurately without the need to consider the above problem.

In some embodiments, the excitation portion 371 may overlap the first region 350a and may not overlap the second region 350b, but is not limited thereto. For example, if the optical sensor unit 400 does not sense the first light L1 emitted from the excitation unit 371, the excitation unit 371 may also overlap a part of the second region 350b.

In some embodiments, the excitation unit 371 may be located on the other side of the first region 350a of each of the plurality of discharge ports 350 in the first direction DR1, but is not limited thereto. Also, in some embodiments, each of the plurality of excitation portions 371 disposed in the first region 350a of each of the plurality of discharge ports 350 may be disposed at the same height, but is not limited thereto.

23 and 24 are diagrams for explaining a nozzle part of an inkjet printing apparatus according to another embodiment.

Referring to FIGS. 23 and 24 , the nozzle unit 302 of the inkjet printing apparatus 1_2 according to the present embodiment illustrates that the area of the light transmitting unit LA_2 may change. In detail, the light transmitting part LA_2 may be formed as a screen and gradually widen in the third direction DR3.

Depending on the embodiment, the amount of ink 90_2 discharged from the nozzle unit 302 may need to be increased. Accordingly, it is necessary to widen the area of the second region 352b of each of the plurality of discharge ports 352 to correspond to the increased amount of ink 90_2.

The area of the light transmitting unit LA_2 may be changed using, for example, a screen-type shielding film. For example, when the amount of the ink 90_2 to be ejected increases, the shield may move in the third direction to increase the area of the light transmitting portion LA_2. In this case, the area of the first area 352a of each of the plurality of discharge ports 352 may decrease, and the area of the second area 352b may increase.

Due to the configuration described above, the inkjet printing apparatus 1_2 according to the present embodiment can flexibly measure the number of bipolar elements 95 required in response to various processes.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. you will be able to understand Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

DD: display device
30: light emitting element
90: ink
91 solvent
95: bipolar element
100: inkjet head unit
300: nozzle unit
400: optical sensor unit
500: ink reservoir
700: probe device

Claims (20)

a stage on which a substrate is placed;
a nozzle unit disposed above the stage and ejecting ink containing a solvent in which the bipolar element is dispersed on the substrate;
Including a plurality of optical sensor units disposed adjacent to the nozzle unit,
The nozzle part:
an excitation unit that excites the bipolar element; and
A plurality of light transmitting units through which first light emitted from the excited bipolar element is transmitted;
The inkjet printing apparatus of claim 1 , wherein each of the plurality of optical sensor units is disposed to face each of the plurality of light transmitting units of the nozzle unit. According to claim 1,
Further comprising an ink storage unit supplying the ink to the nozzle unit,
The nozzle part includes a supply passage through which the ink is supplied from the ink storage part,
The inkjet printing device of claim 1 , wherein the excitation unit is disposed on the supply passage. According to claim 2,
The nozzle unit includes a plurality of discharge ports through which the ink supplied from the supply passage is discharged,
Each of the plurality of light transmitting portions overlaps each of the plurality of discharge ports,
The inkjet printing device of claim 1 , wherein the excitation unit does not overlap with the plurality of light transmitting units. According to claim 3,
The excitation unit emits a second light that excites the bipolar element,
The inkjet printing device of claim 1 , wherein the first light is not irradiated to the plurality of optical sensor units. According to claim 4,
The inkjet printing apparatus of claim 1 , wherein regions other than the plurality of light transmitting portions block the first light. According to claim 1,
The nozzle unit includes a plurality of discharge ports through which the ink is discharged,
Each of the plurality of outlets:
a first region corresponding to and overlapping with each of the plurality of light-transmitting units; and
An inkjet printing device comprising a second area that does not overlap with the plurality of light transmitting units. According to claim 6,
Each of the plurality of optical sensor units overlaps the first region of each of the plurality of discharge ports. According to claim 7,
The excitation unit is disposed in plurality,
Each of the plurality of excitation portions is correspondingly disposed on the second area of each of the plurality of discharge ports. According to claim 8,
The inkjet printing device of claim 1 , wherein the excitation unit emits second light having a wavelength in the ultraviolet region. According to claim 9,
The first light emitted from the bipolar element excited by the excitation unit has a wavelength in the visible ray region. According to claim 10,
Each of the plurality of optical sensor units senses the first light and does not sense the second light. According to claim 7,
The volume of the solvent located in the first region of each of the plurality of discharge ports is the same as the volume of the solvent discharged from each of the plurality of discharge ports. According to claim 12,
The area of the first region of each of the plurality of discharge ports is variable,
The inkjet printing apparatus of claim 1 , wherein an area of each of the plurality of light-transmitting portions is variable to correspond to an area of the first area. According to claim 13,
The inkjet printing apparatus of claim 1 , wherein an area of each of the plurality of light transmitting portions and an area of the first region of each of the plurality of discharge ports are substantially the same. According to claim 7,
An area of each of the plurality of optical sensor units is larger than an area of each of the plurality of light transmitting units. preparing a nozzle unit including a plurality of discharge ports for ejecting ink containing a solvent in which the bipolar element is dispersed and an excitation unit for exciting the bipolar element;
exciting the bipolar element by emitting a first light from the excitation unit;
sensing an amount of second light emitted from the excited bipolar device;
measuring the number of bipolar elements discharged through each of the plurality of discharge ports by sensing the amount of light; and
Among the plurality of outlets, a first outlet in which the number of bipolar elements is measured includes further discharging the ink,
The inkjet printing method of claim 1 , wherein the nozzle unit includes a light transmitting unit transmitting the second light. According to claim 16,
The first light emitted from the excitation unit has a wavelength in the ultraviolet region. According to claim 17,
The second light emitted from the bipolar element has a wavelength in the visible ray region. According to claim 16,
wherein each of the plurality of discharge holes defines a first area overlapping the light transmitting part, and a volume of the solvent located in the first area is equal to a volume of the solvent discharged from each of the plurality of discharge holes. According to claim 16,
In the step of further discharging the ink by the first outlet, the other outlets other than the first outlet among the plurality of outlets do not discharge the ink.

Images