JP2012209108A - Ink jet pattern forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet pattern forming device capable of manufacturing high quality organic functional elements without causing density unevenness by variations of an ink injection amount from each nozzle and further without causing quality deterioration due to a visual rough feeling.SOLUTION: An ink jet pattern forming device injects ink from a plurality of nozzles by injection pattern data and forms at least one functional layer that eliminates density unevenness on a substrate provided with an injection region surrounded by a plurality of matrix-shaped partition walls by using at least one ink jet head that has the plurality of nozzles. In the ink jet pattern forming device, when forming at least one functional layer, the injection pattern data are provided with: reference data for equalizing an average amount of ink at an aperture portion that exists in any region that has a predetermined area; an adjustment table for adjusting the reference data; and a process of calculating an ink amount by a multi-valued error diffusion method.

Description

  The present invention relates to an inkjet pattern forming apparatus that forms a high-definition inkjet pattern.

  In recent years, a film forming technique using an inkjet method has attracted attention. The ink jet method can discharge a minute amount of ink to a desired position according to the resolution of the head used. Therefore, it is easy to form a fine pattern or a thin film having a desired film thickness. It has the characteristics. Taking advantage of this feature, the ink jet method is used for manufacturing organic EL elements and color filters that require fine coating.

  In addition, when the ink jet method is applied to the manufacture of an organic EL device, a necessary amount of an EL material is dispersed or dissolved in a predetermined solvent to form an ink, thereby making the EL material in comparison with a vapor deposition method or a sputtering method. There was an advantage that the utilization efficiency of can be improved.

  However, when pixels are formed by inkjet, there are problems described below.

  FIG. 16 shows an example in which a functional layer is formed, and five inkjet nozzle heads from the inkjet nozzle head 101 to the inkjet nozzle head 105 of the functional layer head that ejects the functional layer ink in the inkjet nozzle head unit are extracted. Show. Reference numeral 51 denotes an area formed by the inkjet nozzle head 101. Similarly, 52 is an area formed by the inkjet nozzle head 102, 53 is an area formed by the inkjet nozzle head 103, 54 is an area formed by the inkjet nozzle head 104, and 55 is formed by the inkjet nozzle head 105. Shows the area. The functional layer 1 pixel in the region 51 (two functional layer pixels in the region 51 in FIG. 16) is formed by the inkjet nozzle head 101. Similarly, the functional layer 1 pixel in the region 52 is applied by the inkjet nozzle head 102, the functional layer 1 pixel in the region 53 is applied by the inkjet nozzle head 103, and the functional layer 1 pixel in the region 54 is applied by the inkjet nozzle head 104. Pixels are formed by the inkjet nozzle head 105. The smaller the variation in the amount of ink ejected and filled in each pixel, the higher the quality can be produced with less density unevenness. However, the amount of ink ejected from the nozzles of the ink-jet nozzle head is between the ink-jet nozzle heads, i.e., the ink-jet. There is variation between the nozzle head 101 and the inkjet nozzle head 105, and there is also variation between the nozzles in the inkjet nozzle head. This is due to differences in the shape and wettability of the open end portions of the nozzles, and variations in the processing state and the fixed state of the pressure generating member.

  In order to solve such a problem, a circuit device that can change the drive voltage value for each nozzle, for example, is incorporated as means for suppressing variations in the ejection ink amount for each nozzle, and an ideal ejection amount such as 10 pl and an actual ejection amount, for example. Patent Document 1 describes a method of reducing variations in ink amount by comparing the above and adjusting the drive voltage value so that the discharge amount becomes the ideal discharge amount.

  Further, by determining the specific opening for changing the discharge amount and the change of the discharge amount based on the degree of density unevenness, the average discharge amount per predetermined area can be made uniform. In addition, by determining the arrangement of the specific opening to change the discharge amount by a random number, a method in which the position in the substrate is dispersed and can be prevented from being recognized as a defect when the entire substrate is observed, It is described in Patent Document 2.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a method in which the ink ejection amount is controlled by a head that has been changed with the applied voltage value of the drive waveform, and the variation is corrected by the combined error diffusion method.

JP 2005-40653 A JP 2007-178906 A JP 2010-115650 A

  However, as shown in Patent Document 1, in order to change and correct the drive voltage value for each nozzle, discharge is performed from each nozzle hole due to the nozzle diameter from each nozzle, the characteristic variation of an actuator such as a piezo element, and the like. It is necessary to grasp all of the effects of so-called crosstalk, etc., that cause the discharge amount to vary between when the discharge amount varies and when the adjacent nozzles discharge at the same timing, and when not discharging. .

Crosstalk is an interference phenomenon caused by pressure interference through the common liquid chamber or current leakage of the piezo element, and the discharge amount when discharging from the adjacent nozzle or at the end of the inkjet head, etc. It means the phenomenon that is different.

For this reason, there is a problem of using enormous amounts of time and materials because the ink discharge and the measurement of the discharge amount are repeated many times for each nozzle, and the operation is performed until the discharge variation of each nozzle is eliminated.

  Further, as shown in the above-mentioned Patent Document 2, since random numbers are used when disposing unique openings having different discharge amounts from the surrounding openings, the amplitude spectrum of the discharge pattern is detected as noise in the human eye. Since the frequency component is included, there is a problem of visually giving a rough feeling.

  In addition, as shown in the above-mentioned Patent Document 3, in order to control the ink discharge amount with the head that has been changed by the applied voltage value of the drive waveform and correct the variation by the combination error diffusion method, the ink jet head for the combination is used for the ink jet. Since it must be arranged in the head unit, the film thickness variation occurs only with the binarized error diffusion method. Since there is a possibility that the functional layer of the organic EL must be as small as possible, it is not possible to use it from the viewpoint of quality by laminating the method of making it zero by binarization. There's a problem.

  The present invention has been made in view of the above-described problems, and has high density organic functional elements and color without density unevenness caused by variations in the ink discharge amount for each nozzle and without quality deterioration due to visual roughness. An object of the present invention is to provide an ink jet pattern forming apparatus capable of manufacturing a filter.

According to a first aspect of the present invention, at least one inkjet head having a plurality of nozzles is used on a substrate provided with a discharge region surrounded by a plurality of matrix-like partition walls, and the nozzles are determined according to discharge pattern data. In an inkjet pattern forming apparatus for forming at least one functional layer in which density unevenness is eliminated by discharging ink from
When forming the functional layer,
The ejection pattern data is calculated by reference data for making the average amount of ink in an opening existing in an arbitrary area having a predetermined area uniform, an adjustment table for adjusting the reference data, and a multi-value error diffusion method. Process,
An inkjet pattern forming apparatus.

  In the invention according to claim 2 of the present invention, in the adjustment table, the opening for adjusting the liquid volume by ± α and the opening for not adjusting the liquid volume are arranged in the direction of 45 degrees, and ± α in the vertical and horizontal directions. 2. The inkjet pattern forming apparatus according to claim 1, wherein the data is arranged so as to be sandwiched between openings where the liquid amount adjustment is not performed, and data for the entire surface of the substrate opening is arranged in a repetitive pattern.

  According to a third aspect of the present invention, the amount of liquid allocated from the target opening to the surrounding opening by the multi-value error diffusion method is the ink amount of the target opening determined by the reference data and the adjustment table. The inkjet pattern forming apparatus according to claim 1, wherein the remainder obtained by dividing the unit drop amount of the inkjet head is determined by diffusing with an error diffusion filter weighted according to a direction viewed from the target opening. is there.

  In the invention according to claim 4 of the present invention, when a plurality of functional layers are formed, the increase / decrease position of the drop amount in the ejection pattern data is not matched with the allocation position of the functional layer formed in the lower layer as much as possible. The inkjet pattern forming apparatus according to claim 1, wherein the increase / decrease position is adjusted as described above.

  In the invention according to claim 5 of the present invention, the increase / decrease position of the drop amount in the ejection pattern data is such that the variation in the film thickness of each pixel of the functional layers stacked in the main scanning direction of the substrate is reduced. The inkjet pattern forming apparatus according to claim 1, wherein an increase / decrease position is adjusted.

  The invention according to claim 6 of the present invention is a self-luminous member in which at least one of the laminated functional layers emits light when a current is applied. Inkjet pattern forming apparatus.

  The invention according to claim 7 of the present invention is a method for manufacturing an organic functional element in which a plurality of organic functional layers are formed on a substrate, and the inkjet pattern forming apparatus according to any one of claims 1 to 6, An organic functional device is produced by forming an organic functional layer.

  According to the present invention, it is possible to suppress density unevenness and visual roughness caused by variations in ink discharge amount between inkjet nozzle heads and between nozzles, and to achieve high-quality organic functions with high definition and less density unevenness. Active elements and color filters can be manufactured in a short time.

It is a schematic diagram of an organic EL element substrate cross section. 1 is an outline view showing an example of the overall configuration of an inkjet pattern forming apparatus according to the present invention. It is a figure for demonstrating the inkjet nozzle head unit of the inkjet pattern formation apparatus of this invention. It is explanatory drawing of the nozzle head of the inkjet pattern formation apparatus which concerns on this invention. It is a figure which shows the mode of the applied voltage waveform applied to each phase of the A phase of the nozzle head which concerns on this invention, B phase, and C phase, and the discharge state of ink. It is the schematic which selects an effective nozzle from the nozzle of the nozzle head unit which concerns on this invention. It is a figure for demonstrating how to obtain | require the reference | standard data based on this invention. It is a figure which shows the example of arrangement | positioning of the reference data based on this invention. It is a figure which shows the coefficient example of the filter which distributes the difference with the unit drop concerning this invention. It is a figure showing a VTF curve. It is a conceptual diagram showing the period of a color nonuniformity. It is a figure which shows the example of arrangement | positioning of the adjustment table data based on this invention. It is a figure which shows the example of a mapping using an adjustment table. It is a figure for demonstrating the means to set the discharge amount of the ink discharged at once based on this invention. It is the schematic which shows the adjacent luminance value of each cell with and without the nonuniformity adjustment of an organic EL board | substrate. It is a figure for demonstrating the problem in the case of forming a functional layer pixel by inkjet.

  Next, an inkjet pattern forming apparatus according to an embodiment of the present invention will be described in detail.

  Hereinafter, in the present invention, the hole transport layer, the electron blocking layer, and the organic light emitting layer of the organic EL element are collectively referred to as a functional layer, and a case where they are formed by a three-layer ink jet method will be described. Details of the forming method by the ink jet method will be described later. First, the structure of the organic EL element will be described with reference to FIG.

  The organic EL element is formed on the substrate. A translucent substrate is preferably used as the substrate. As the translucent substrate 1, a glass substrate or a plastic film or sheet can be used. When a plastic film is used, a polymer EL element can be produced by winding, and a display panel can be provided at a low cost.

  Examples of the plastic film that can be used include polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, and polycarbonate.

  These films are made of a metal oxide such as silicon oxide that exhibits water vapor barrier property and oxygen barrier property, oxynitride such as silicon nitride, polyvinylidene chloride, polyvinyl chloride, ethylene saponified vinyl acetate copolymer. It is preferable to provide a barrier layer as necessary.

  A pixel electrode 2 patterned as an anode is provided on the translucent substrate 1. As the material of the pixel electrode 2, transparent electrode materials such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), tin oxide, zinc oxide, indium oxide, and aluminum oxide composite oxide can be used.

  It is preferable to use ITO because of its low resistance, solvent resistance and transparency. ITO is formed on the translucent substrate by sputtering, and is patterned by photolithography to form line-shaped pixel electrodes 2.

  After the line-shaped pixel electrode 2 is formed, a partition wall 3 is formed by a photolithography method using a photosensitive material between adjacent pixel electrodes.

  A matrix-like partition is provided on the substrate and the inspection substrate, and a region surrounded by the partition serves as a discharge region in which a film made of inkjet ink is formed. The photosensitive material for forming the partition walls may be either a positive resist or a negative resist, but it must have insulating properties. If the partition walls do not have sufficient insulating properties, current flows to the adjacent pixel electrodes through the partition walls, resulting in display defects. Specific examples include polyimide, acrylic resin, novolac resin, and fluorene, but the present invention is not limited thereto. Further, for the purpose of improving the display quality of the organic EL element, a light shielding material may be included in the photosensitive material.

  The partition wall 3 in the present invention desirably has a thickness of 0.5 to 5.0 μm. By providing the partition wall 3 between adjacent pixel electrodes, it is possible to suppress the spread of the hole transport ink printed on each pixel electrode and to prevent occurrence of a short circuit from the edge of the transparent conductive film. If the partition walls are too low, the effect of preventing a short circuit may not be obtained, so care must be taken.

  After the partition walls are formed, the hole transport layer 4 is formed. In the present invention, the hole transport ink for forming the hole transport layer 4 is preferably an organic solvent-based ink that has a small ion attack to the ink jet head.

In addition, the volume low efficiency of the hole transport layer to be formed is preferably 1 × 10 ⁶ Ω · cm or less from the viewpoint of light emission efficiency.

  Examples of the solvent for dissolving or dispersing the hole transport material include halogen solvents such as chloroform, dichloromethane, dichloroethane, trichloroethylene, ethylene dichloride, tetrachloroethane, chlorobenzene, N-methyl-2-pyrrolidone (NMP), dimethyl Polar solvents such as aprotic polar solvents such as formamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and alkoxy alcohols such as propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol monoethyl ether Etc. are raised.

  A functional ink containing a hole transport material is ejected to the translucent substrate 1 on which the partition walls 3 baked as described above are formed by an ink jet method described later, and the hole transport layer 4 is formed.

  After the hole transport layer 4 is formed, a functional ink containing an electron blocking substance is ejected by an ink jet method described later to form the electron blocking layer 5. The electron blocking layer is a layer for blocking electrons in order to prevent electrons injected from the hole transport layer 4 into the organic light emitting layer 6 from passing to the cathode as they are, and is composed of an electron blocking material.

  Examples of the electron blocking substance include poly (N-vinylcarbazole) (hereinafter also referred to as PVK), poly (para-phenylene vinylene), carbazole biphenyl (hereinafter also referred to as CBP), N, N′-diphenyl- N, N′-bis (1-naphthyl) -1,1′-biphenyl-4,4′-diamine (hereinafter also referred to as NPD), N, N′-diphenyl-N, N′-bis (3-methyl) Phenyl) -1,1′-biphenyl-4,4′-diamine (hereinafter also referred to as TPD), 4,4′-bis (10-phenothiazinyl) biphenyl, 2,4,6-triphenyl-1, Examples include 3,5-triazole, polyfluorene derivatives, and a copolymer of triphenylamine and fluorene.

  After the electronic block layer 5 is formed, a functional ink containing an organic light emitting material is ejected by an ink jet method to form the organic light emitting layer 6. The organic light emitting layer 6 is a layer that emits light by passing an electric current, and the organic light emitting material forming the organic light emitting layer 6 is, for example, a coumarin type, a perylene type, a pyran type, an anthrone type, a porphyrene type, a quinacridone type, N, N'-dialkyl-substituted quinacridone-based, naphthalimide-based, N, N'-diaryl-substituted pyrrolopyrrole-based, iridium complex-based luminescent dyes dispersed in polymers such as polystyrene, polymethylmethacrylate, polyvinylcarbazole, etc. And polyarylene-based, polyarylene vinylene-based, and polyfluorene-based polymer materials.

  Examples of the solvent for the functional ink that forms the electron blocking layer 5 and the organic light emitting layer 6 include cymene, tetralin, cumene, decalin, durene, cyclohexylbenzene, dihexylbenzene, tetramethylbenzene, and dibutylbenzene. More preferably, the boiling point is 220 ° C. or higher, and the vapor pressure at room temperature is 0.10 to 10 mmHg.

  It is also preferred that the functional ink for forming the hole transport layer has a viscosity of 3 to 20 cps and a surface tension of 25 to 35 mN / m. Since the viscosity can be adjusted to be suitable for ejection by using the solvent, the functional layer can be easily formed. According to the said solvent, since the solubility of a material is large, precipitation of the content after functional ink preparation can be prevented. In addition, in forming a functional layer using the inkjet method, the solubility of the functional material is large in order to prevent clogging and flight bending during ejection due to solvent volatilization or precipitation of contents, and to realize stable ejection. High boiling point and / or low vapor pressure solvents are desirable.

  After the organic light emitting layer 6 is formed, the cathode layer 7 is formed in a line pattern orthogonal to the pixel electrode line pattern. As the material of the cathode layer 7, a material according to the light emitting characteristics of the organic light emitting layer can be used. For example, a simple metal such as lithium, magnesium, calcium, ytterbium or aluminum or a stable metal such as gold or silver can be used. An alloy etc. are mentioned. Alternatively, a conductive oxide such as indium, zinc, or tin can be used. Examples of the method for forming the cathode layer include a method using a vacuum vapor deposition method using a mask.

  Finally, in order to protect these organic EL constituents from external oxygen and moisture, a glass cap 8 and an adhesive 9 are hermetically sealed to obtain an organic EL display panel. Moreover, when a translucent board | substrate has flexibility, you may seal using a sealing agent and a flexible film.

  The organic EL device of the present invention has a structure in which a hole transport layer, an electron blocking layer, and an organic light emitting layer are laminated from the anode layer side between a pixel electrode that is an anode and a cathode layer. In addition to the hole transport layer and the organic light emitting layer, a layered structure in which layers such as a hole block layer, an electron transport layer, and an electron injection layer are selected as necessary can be adopted. Moreover, when forming these layers, the formation method similar to a light emitting layer can be used.

  Next, a method for producing an electron transport layer, an electron block layer, and an organic light emitting layer, which are functional layers of the EL element substrate of the present invention, by an inkjet method will be described in detail.

  FIG. 2 is an overall configuration example of an inkjet pattern forming apparatus according to the present invention, and an inkjet pattern forming apparatus main body including an inkjet nozzle head unit 60 including a plurality of inkjet nozzle heads 62 and a table 61 on which a substrate 50 is placed. 64 and an inkjet nozzle head unit controller 65.

  Further, the pattern formation is performed by moving the table 61 on which the substrate 50 is placed in the main scanning direction (Y direction in FIG. 2) and moving the inkjet nozzle head unit 60 in the sub scanning direction (X direction in FIG. 2). Is done.

  The table 61 of the ink jet pattern forming apparatus according to the present invention can be moved in the sub-scanning direction, and can be rotated about the center of the table 61. The pixel of the substrate placed on the table 61 and the ink jet nozzle head. The units 60 can be aligned in parallel, and the table 61 is provided with a suction mechanism (not shown), and the substrate placed on the table 61 can be fixed.

  FIG. 3 is a diagram for explaining the inkjet nozzle head unit 60 of the inkjet pattern forming apparatus of the present invention. In order to manufacture an organic EL element, an electron transport layer, an electron block layer, an organic light emitting layer (RGB 3) It is necessary to eject five types of ink. Among these, FIG. 3 illustrates an organic light emitting layer (three colors of RGB) as an example. There is an ink jet nozzle head 44-1 in which a plurality (two in FIG. 3) of nozzle heads 42 and nozzle heads 43 having a plurality of nozzles (not shown) are arranged in the main scanning direction, Further, a plurality of inkjet nozzle heads (5 in FIG. 3) are arranged in the sub-scanning direction such as inkjet nozzle head 44-2, inkjet nozzle head 44-3, inkjet nozzle head 44-4, and inkjet nozzle head 44-5. The R head 46, the G head 47 and the B head 48 arranged in the same manner are arranged in the main scanning direction.

  FIG. 4 shows a nozzle head of the ink jet pattern forming apparatus according to the present invention. The nozzle head can eject ink in the shear wave mode. The drive method of the nozzle head in the share wave mode is that a plurality of pressure chambers filled with ink are formed by bonding and fixing two piezoelectric ceramics, and then cutting, and the piezoelectric member forming each pressure chamber is used as an actuator. In this method, a drive pulse voltage is selectively applied to the actuator and deformed, thereby causing a pressure change and controlling the discharge of one or a plurality of drops.

  FIG. 4 (a) is a view of a bonded surface of two piezoelectric ceramics processed in a comb-like shape, as seen from the nozzle surface. Each piezoelectric ceramic is provided with an electrode (not shown) in advance. Then, in the portions marked A, B, C, A... In the drawing, a liquid chamber having a depth of, for example, 0.5 mm or 1 mm is formed in the depth direction from the surface, and the liquid chamber is filled with ink.

  FIG. 4B shows a nozzle plate portion to be bonded to the piezoelectric ceramic shown in FIG. 4A. Like the liquid chamber, A, B, C, A (hereinafter referred to as A phase, B phase, C phase). , A phase)...

  FIG. 4C shows an example of waveforms applied to two piezoelectric ceramics in contact with the A phase.

  The state 3-1 in FIG. 4 shows a state in which no voltage is applied to any of the A-phase, B-phase, and C-phase piezoelectric ceramics.

  In the state of 3-2 in FIG. 4, voltage application (positive voltage application) is performed in a direction in which two piezoelectric ceramics in contact with the A phase are spread (active operation).

  In the state 3-3 in FIG. 4, a voltage is applied (a negative voltage is applied) in a direction in which the two piezoelectric ceramic liquid chambers in contact with the A phase are contracted (inactive operation). At this time, ink is ejected from the A-phase nozzle indicated by 70. When ink is ejected from the A-phase nozzle, adjustment is made so that it is not ejected from the adjacent phases of the B-phase and C-phase.

  The state 3-4 in FIG. 4 represents a pause period (OFF operation: OFF) in which the residual vibration remaining in the A phase is attenuated and disappears.

  Thereafter, the ink drop can be ejected from all the nozzles by repeating the ejection in the B phase and the C phase. That is, the three-phase division driving is repeated in the order of A phase → B phase → C phase → A phase. FIG. 5 shows an applied voltage waveform applied to each of the A phase, the B phase, and the C phase and how ink is ejected. The table on which the substrate is mounted is moved in the main scanning direction, and is synchronized with a synchronization signal generated by the amount of movement of the table (for example, a synchronization signal that generates one pulse signal every time the table moves 1 μm in the main scanning direction). Thus, a drop of ink is ejected from each phase.

  For example, an inkjet nozzle head unit controller 65 shown in FIG. 2 is connected to the inkjet pattern forming apparatus main body 64 as control means for ejecting ink from the nozzles of the inkjet nozzle head unit based on the pattern formation information. The ink jet nozzle head unit controller 65 drives the ink jet nozzle head unit, and stores pattern formation information created from nozzle parameter information and substrate parameter information. The nozzle parameter information is information for driving the inkjet nozzle head unit, and includes nozzle array data, nozzle head array data, inkjet nozzle head array data, and ink discharge amount data. The substrate parameter information is information indicating the position of the pixel in the substrate, and includes the size of the substrate, imposition information in one substrate, and pixel arrangement data. The nozzle parameter information The pattern formation information created from the substrate parameter information is information on how much ink each nozzle ejects at which position on the substrate, and the pattern formation information from the nozzle head unit controller to each nozzle when performing ejection Is output, and pattern formation can be performed.

  In order to drive the inkjet nozzle head unit of the inkjet nozzle head unit controller 65, it is preferable that an optimum voltage value can be set for each inkjet nozzle head. If the drive voltages of all the ink jet nozzle heads are set to the same value, there is an individual difference in the amount of ink ejected from the ink jet nozzle head, and there is a possibility that ink cannot be uniformly ejected into the substrate. By making it possible to set the optimal voltage value parameter for each inkjet nozzle head, it becomes possible to control the ejection amount for each inkjet nozzle head, and as a result, the ejection amount for each pixel can be controlled more accurately. Can do.

  In pattern formation by ink jet, it is necessary to control the landing position of the ink drop in addition to controlling the ejection amount of the ink drop to each pixel. For this, the positions of the ink jet nozzle head unit and the ink jet nozzle head are calculated from the nozzle parameter information and the substrate parameter information inputted in advance and the movement amount of the table of the ink jet pattern forming apparatus, and the ink ejected from the nozzle onto the substrate. Determine the landing position. In addition, the landing position of the ink drop may be controlled by obtaining an image of the substrate surface with a camera installed in the inkjet pattern forming apparatus and calculating the landing position of the ink.

  After the positions of the ink jet nozzle head unit and the ink jet nozzle head are calculated with respect to the pixels on the substrate, the program determines whether the ink landing position is the target pixel based on this position information. To do. The nozzle is selected as an effective nozzle only when the landing position corresponds to the target pixel, and ink is ejected from the nozzle, and is not ejected from a nozzle that is not an effective nozzle.

  FIG. 6 is a diagram showing a specific example of means for selecting an effective nozzle for ejecting ink. 6 shows an ink jet nozzle head 44-1 extracted from the nozzle head 42 and the nozzle head 43 of the R head 46 shown in FIG. 3, for example, 11 indicates a partition pattern, 12 indicates a pixel. The nozzle 31 corresponding to this is determined to be valid, and the other nozzles are determined to be invalid, and pattern formation information is generated from the result. Then, according to this pattern formation information, ink is ejected from the nozzle 31 indicated by the arrow in FIG.

  Here, when the inkjet pattern forming apparatus and the pattern forming method of the present invention are not used, in the main scanning direction, when the variation in the ejection amount for each pixel is small, that is, the standard deviation of the ejection amount of each pixel (main scanning) Even when the standard deviation of the discharge amount in the direction is small, the standard deviation of the discharge amount between the main scanning directions (standard deviation of the discharge amount between the main scanning directions) becomes the standard deviation of the discharge amount in the main scanning direction. Since it is larger than the above, density unevenness due to the difference in the discharge amount occurs, and the organic EL element is visually large in density unevenness as a whole.

  Therefore, the ink jet pattern forming apparatus of the present invention has a means for calculating the increase / decrease in the number of ink drops ejected from the effective nozzles for each pixel from the reference data by using the multi-value error diffusion method. Resolve. In other words, by increasing or decreasing the number of drops actually ejected for each pixel with respect to the number of drops to be ejected to the pixels, the width of the main scanning direction can be arbitrarily varied, and each main scanning direction can be varied. Variations in the average discharge amount can be made inconspicuous, and the roughness that occurs when the total amount of diffusion is increased or decreased by being diffused can be suppressed, whereby overall density unevenness can be reduced.

  More specifically, first, a means for obtaining the frequency for increasing or decreasing the number of ink drops ejected from the effective nozzles for each pixel will be described.

  FIG. 7 is a diagram for explaining how to obtain the reference data. FIG. 7 schematically shows the arrangement of RGB pixels in the organic light emitting layer. In the main scanning direction (column direction in FIG. 7), 10 R pixels, 10 G pixels, and 10 B pixels are consecutive. The continuous R, G, B pixels are formed in nine columns in the sub-scanning direction (row direction in FIG. 7). In order to obtain the reference data, first, RGB pixels on the entire surface of the organic light emitting layer are formed on a test basis using an inkjet pattern forming apparatus. Next, for example, the film thickness of each of RGB pixels along B1 and B2 is measured by a film thickness meter, and the amount of ink in each pixel is read (in FIG. 7, three pixels each of R, G, and B along B1 and B2). The total amount of ink of 9 pixels is read). The film thickness and the ink liquid amount are related in advance, and the ink liquid amount of each pixel is read from the measured film thickness. Next, the number of drops required to obtain a desired film thickness is obtained from the read ink amount of each pixel, and reference data is calculated from the number of drops.

  The procedure up to reading the ink amount of each pixel will be described in more detail. When the RGB pixels of the organic light emitting layer are formed on a test basis, for example, 200 pl (effective) is obtained to obtain a film thickness of 100 nm with a nozzle that discharges 10 pl per nozzle to 10 pixels of the R pixel indicated by hatching. Ink drops of 20 nozzles are ejected to form pixels (200 pl is the target ink liquid amount and the ink amount that can achieve the target ink film thickness) .R along B1 and B2 It is assumed that the result of measuring the film thickness of the pixel 82 is 96 nm, based on a calibration curve composed of the film thickness and the ink liquid amount that are related in advance (in this case, the film thickness and the ink liquid amount are in a linear relationship). 96 nm corresponds to 200 * (96/100) = 192 pl), and the ink amount is read as 192 pl.In actuality, only 192 pl is ejected with respect to 200 pl. The average discharge rate of 1 drop per le becomes (192/200) * 10 = 9.6pl.

Next, a procedure for obtaining the number of drops necessary for obtaining a desired film thickness from the read ink amount of each pixel and calculating reference data from the number of drops will be described. Since the desired film thickness is 100 nm, the R pixel 82 measured for the film thickness includes
(10 / 9.6) * 20 = 200 / 9.6 = 20 + (8 / 9.6)
It is necessary to eject the ink of the number of drops.

  However, since 8 / 9.6 drops of ink cannot be ejected, 20 drops or 21 drops of ink are ejected. The liquid volume of the 8 / 9.6 drop is “(8 / 9.6) * 9.6 = 8 (pl)”. This 8 pl is used as reference data. This reference data 8pl indicates that one drop is added to four of the five pixels and 21 drops are discharged, and 20 drops are discharged to one pixel. As a result, the drop amount discharged to the five pixels is (21 * 4 + 20 * 1) * 9.6 = 998.4 (pl), and the average drop amount per pixel is 199.68 pl, which is almost the target liquid amount. Is equal to

  In addition to the film thickness meter, a chromaticity meter, luminance meter, light emission luminance, PL light emission, or the like can be used as long as the measurement reading value and the ink amount are related. As described above, in the present invention, it is only necessary to have one reference data for one main scanning direction.

  Next, means for allocating to the pixels that increase or decrease the number of ink drops will be described. FIG. 8 shows an example of a method for arranging reference data. FIG. 8 is a layout diagram of monochrome reference data. As shown in FIG. 8, the reference data obtained in each measurement is arranged in each pixel in the sub-scanning direction, and the reference data arranged in the sub-scanning direction is repeatedly arranged in the main scanning direction.

  Multilevel error diffusion processing is started with the upper left pixel in FIG. 8 as a reference position.

  In order to determine the number of drops S to increase / decrease the pixel at the reference position, A is the reference data value at the reference position, D is the amount of one drop discharged from one nozzle of the inkjet nozzle head (hereinafter referred to as unit drop amount), If the control number of drops to be ejected from the inkjet nozzle head (hereinafter referred to as the number of gradations) is B, the following equation is obtained.

a = floor ((A + (D × B) + (D / 2)) / D) (1)
S = a−B (2)
E = A−S × D (3)
The above formula E is a difference value that cannot be discharged by a unit drop at the reference position. The difference value E, which cannot be ejected by this unit drop, is distributed to surrounding pixels by a filter coefficient as shown in FIG.

  The pixel on the right side as viewed from the target pixel adds to the reference data a value obtained by 7/16 * X from the total value 16 of the filter coefficients in FIG. 9 and the coefficient 7 on the right side of the target pixel. Hereinafter, the calculation is performed using filter coefficients in the corresponding direction in the order of lower left, lower, and lower right. Next, the same calculation is performed with the pixel of interest as the pixel on the right. When the calculation for all the pixels in the first row is completed, the calculation for the pixels in the second row is similarly performed from the left end toward the right end. Thereafter, the calculation is performed in the same manner from the third line to the last line, and the calculation ends at the lower right pixel. Note that the selection procedure of the pixel of interest is not limited to this example, such that the odd rows are calculated from the leftmost pixel toward the rightmost pixels, and the even rows are calculated in the opposite direction.

  Here, as one of image evaluation methods such as a screen, a lens, and an optical filter, MTF (Modulation Transfer Function) representing the reproducibility of the contrast and resolution of the output image of various optical members with respect to the input image is widely used. In particular, when observing an object with human eyes, it is common to use VTF (Visual Transfer Function), which is an MTF of the visual system, as one measure of whether or not it is perceived sensitively.

  FIG. 10 shows a VTF curve at an observation distance of 286 mm. From FIG. 10, the VTF curve shows a bandpass characteristic having a peak at 1 cycle / mm. Further, it has been confirmed through experiments and the like that the less the frequency component remaining when the VTF curve is multiplied by the amplitude spectrum of the image, the less the feeling of roughness with the human eye.

  On the other hand, the density unevenness with the shortest period in the density unevenness of the organic EL substrate is when light and dark are repeated between adjacent cells (0.5 cycle / cell) as shown in the upper part of FIG. Since the width of the opening of the organic EL substrate is about 200 μm, 0.5 cycle / cell is 0.4 cycle / mm, which causes density unevenness. In the case of a color filter, since the width of the opening is about 500 μm, 0.5 cycle / cell is 1 cycle / mm.

  In order to obtain a discharge pattern that is less likely to feel rough to the human eye in density unevenness adjustment, it is better that the frequency component remaining when the amplitude spectrum of the liquid amount distribution with respect to the opening of the entire substrate is multiplied by the VTF curve is smaller.

  Next, the granularity that is an evaluation parameter used in the present invention will be described. Note that the calculation method is not limited to this as long as it is an evaluation parameter obtained by multiplying the above-described amplitude spectrum and VTF curve.

P [cycles / mm] is a frequency component of a pattern composed of openings in the sub-scanning direction, q [cycles / mm] is a frequency component of a pattern composed of openings in the main scanning direction, and R [mm] is an observation distance. Then, the VTF curve VTF (p, q) is expressed by the following equation.

Next, the winner spectrum W (p, q) is obtained by multiplying the amplitude spectrum F (p, q) of the liquid volume distribution with respect to the opening of the entire substrate by the VTF curve.

The integral value of the Wiener spectrum W (p, q) is defined as the granularity G. The smaller the value of the granularity G, the fewer components that make the human eye feel rough.

  When the error diffusion method is used, moire may occur. As a method of removing this moire, it is said that by arranging dots of singular points in the 45 degree direction, the singular points are not easily noticeable and can be seen in a natural state.

  As a method of arranging singular points in the 45 degree direction as much as possible, it is possible by adding an adjustment table to the reference data. The values in the adjustment table are preferably three types of combinations of 0, + α, and −α. FIG. 12 shows an example of the adjustment table.

In FIG. 12, α = 1. +1 and -1 are sandwiched by 0, and each value is arranged at 45 degrees (oblique), so that singular points can be arranged in the 45 degree direction.

  Further, +1 and −1 in FIG. 12 need to be the same number. If +1 and −1 are the same number, the average of the total values of the adjustment tables is 0, and the average of the values of the reference data is hardly deviated, and there is no problem even if adjustment data is added.

  If the adjustment data is a combination of four or more including + α in addition to + α and −α, including 0, the standard deviation of the values in the adjustment table becomes large and may cause roughness. In addition, in order to generate singular points in the adjustment table, three types of combinations that reduce the number of combinations as much as possible are preferable.

  When the number of combinations is + α and −α2 types, the standard deviation of the values in the adjustment table is larger than that in the case of three types of combinations, which causes roughness.

For example,
(1) Three types of combinations of +1, 0, -1, 0 (2) Two types of combinations of +1, -1 When comparing the above (1) and (2) granularity, the same opening width and the same numerical aperture When implemented, the granularity G when the observation distance is 250 mm is (1) 0.3948 and (2) 0.5094, and it is known that three types of combinations are excellent even when compared with the granularity G.

  FIG. 13 shows an actual mapping example. A cell with a liquid volume as standard, a cell with a liquid volume larger than the standard, and a cell with a liquid volume smaller than the standard tend to be aligned in the 45 degree direction (when focusing on one of white, red, and blue, the 45 degree direction Are lined up).

  Next, a means for selecting a nozzle for increasing or decreasing the number of ink drops will be described. Nozzles that increase or decrease the number of drops are selected from the effective nozzles described above, but are most affected by differences in the number of discharge drops between adjacent nozzles and the effect of crosstalk that changes the discharge amount due to overlapping of discharge times. Choose not to. Furthermore, the nozzle which increases / decreases the number of drops by selecting the unit drop amount described below is selected.

  In the case of inkjet in the share wave mode, the ink ejection amount changes due to the influence of the crosstalk. For this reason, the target ink amount cannot be ejected and filled in the pixel. In order to solve this problem, the nozzle for discharging is selected so as not to be affected by the crosstalk as described above, or the nozzle is further selected by weighting.

  The reason for weighting will be described next.

  For the nozzle method for increasing or decreasing the number of drops, a nozzle that discharges so as to be least affected by crosstalk is selected. As described above, the nozzles used in the inkjet nozzle head are arranged at the open end of each nozzle. There are variations in the amount of liquid discharged due to differences in shape and wettability, variations in the processing state of the pressure generating member, and variations in the fixed state. Therefore, for example, when one nozzle is selected from the effective nozzles in FIG. 6 (13 in the case of FIG. 6) and the liquid volume is increased by 9.6 pl, the liquid is discharged from 13 nozzles. Therefore, it is desirable to select a nozzle that discharges the liquid amount closest to 9.6 pl. As a result, an optimal liquid amount can be discharged to the pixels. For this reason, it is desirable to set the ejection amount of ink ejected at a time from a plurality of nozzles used in the inkjet nozzle head unit, that is, the liquid amount of one drop.

  Therefore, the present invention has means for setting the ejection amount of ink ejected from each nozzle of an inkjet nozzle head having a plurality of nozzles at one time, and the ejection amount is weighted as the unit drop amount of each nozzle.

  The amount of ink discharged from each nozzle at one time is set by measuring the amount of one drop of ink discharged from each nozzle. Next, the measuring method will be described below.

  FIG. 14 is a diagram for explaining a method of measuring the amount of one drop of liquid from all nozzles. Reference numeral 90 denotes a substrate, 91 denotes a partition pattern, 92 denotes a nozzle, and 93 denotes a nozzle head. 14A is a schematic diagram in which the nozzles 92 are arranged, FIG. 14B is an enlarged view of the nozzles 92 in which the nozzles 92 are arranged, and FIG. 14C shows a cross section of the substrate on which the partition pattern 91 is formed. FIG. The nozzle 92 is a repetition of the A phase, the B phase, and the C phase, and the partition pattern 91 is formed on the substrate 90, for example, at a pitch P of the A phase nozzle 92 over a plurality of rows (not shown). . First, one or a plurality of drops are ejected from the A-phase nozzle to the pixels formed by the partition wall pattern 91, and then the nozzle 90 is placed on the nozzle head 93 by a table (not shown) on which the substrate 90 is placed. After moving one row, one or more drops are ejected from the B-phase nozzle in the same manner as the A-phase nozzle, and then the drop is ejected from the C-phase nozzle in the same manner. Thereafter, the film thickness of each pixel is measured with a film thickness meter, and the amount of liquid ejected from the result is obtained, and the amount of one drop of each nozzle is obtained over all nozzles.

  The obtained one drop liquid amount of each nozzle is weighted as a unit drop amount.

  By considering the unit drop amount, the above weighting can correct the variation in the ink amount ejected to the pixels in the main scanning direction of the ejection amount, and the target ejection amount can be weighted. The standard deviation can be made smaller than in the case where it is not performed, and it is possible to approach the target discharge amount as much as possible.

  As described above, according to the method of the present invention, it is possible to reduce density unevenness between pixels. Further, it is possible to apply a coating that absorbs all of the variations and the like by eliminating the influence of the variation and crosstalk of each nozzle, and a substrate having no unevenness can be manufactured even in a stacked substrate.

  Next, the manufacturing method of the organic EL element of this invention is demonstrated as an Example.

  An ITO (indium-tin oxide) thin film was formed on a 3-inch glass substrate by sputtering, and the ITO film was patterned by photolithography and etching with an acid solution to form a pixel electrode. The line pattern of the pixel electrode was a pattern in which a line width of 70 μm, a space of 60 μm, and a line of about 590 × 159 were formed in a square of about 7.6 mm.

  Next, an insulating layer was formed as follows. First, a polyimide resist material was spin-coated on the entire surface of a glass substrate on which pixel electrodes were formed. The spin coating condition was rotated at 150 rpm for 5 seconds, and then rotated at 500 rpm for 20 seconds to form a single coating. The height of the insulating layer was 2.5 μm. An insulating layer having a line pattern between pixel electrodes was formed by photolithography on the photoresist material applied to the entire surface. This insulating layer has liquid repellency.

  Next, as a hole transporting ink, a PEDOT / PSS (poly3,4-ethylenedioxythiophene) / (polystyrene sulfonate) solution Baitron P CH-8000 (manufactured by H.C. Starck) was used. An ink having a solid content concentration of 1.5%, a viscosity of 15 mPa · s, and a vapor pressure of 1.1 kPa was prepared. A hole transport layer was formed on the entire surface of the substrate by the slit method under conditions of humidity 45% and temperature 25 ° C. using ink and a plate. Thereafter, unnecessary portions outside the pixel region were wiped off with a waste cloth and dried in the atmosphere at 200 ° C. for 30 minutes to form a hole transport layer. The film thickness at this time was 50 nm.

  Next, the electronic block material was dissolved in a solvent so that the concentration of the coating ink was 1.0% by weight to prepare a coating ink for forming an electronic block layer. Here, the electron block material refers to an electron block material made of a polyfluorene derivative. The ink solvent composition was 99% by weight of cyclohexylbenzene (boiling point 237.5 ° C.). At this time, the surface tension of the ink was measured by the plate method and found to be about 34.3 mN / m. The viscosity was 9.2 mPa / s (25 ° C.) as measured with an E-type viscometer. The vapor pressure was 0.975 mmHg (67.5 ° C.).

  Next, an electronic block layer was formed on the substrate formed up to the hole transport layer using the inkjet pattern forming apparatus of the present invention shown in FIG. The discharge amount per cell is about 120 pl. Thereafter, an electronic block layer was formed in an oven at 200 ° C. for 15 minutes. At this time, the thickness of the electron blocking layer was 20 nm. The result of measuring the formed electronic block layer with a luminance meter is defined as reference data A. Based on the relationship between the reference data A using the adjustment table shown in FIG. 12 and the unit drop amount D ejected from the nozzles of the inkjet nozzle head is 6 pl and the gradation number B (= 15) of the inkjet nozzle head is set. As a whole, it was possible to form an electron block layer having no variation.

  Next, the organic light emitting material was dissolved in a solvent so that the concentration of the coating ink was 1.0% by weight to prepare a light emitting layer forming coating ink. Here, the polymeric fluorescent substance refers to a light emitting material made of a poly (paraphenylene vinylene) derivative. The ink solvent composition was 99% by weight of cyclohexylbenzene. At this time, the surface tension of the ink was measured by the plate method, and was about 35 mN / m.

  Next, an organic light emitting layer was formed on the substrate formed up to the electronic block layer using the inkjet pattern forming apparatus of the present invention shown in FIG. The discharge amount per cell is about 240 pl. Thereafter, an organic light emitting layer was formed in an oven at 130 ° C. for 10 minutes. The film thickness of the organic light emitting layer at this time was 80 nm. The result of measuring the formed organic light emitting layer with a luminance meter is defined as reference data A. The unit drop amount D ejected from the nozzle of the inkjet nozzle head is 6 pl, the reference data A using the adjustment table shown in FIG. 12, and the unit drop amount D ejected from the nozzle of the inkjet nozzle head is 6 pl. Due to the relationship of the number of gradations B (= 15) of the inkjet nozzle head, there was no deviation from the target, and an organic light emitting layer having no variation as a whole could be formed.

  FIG. 15 shows the result of the adjacent luminance difference between each pixel of the emission luminance of the unadjusted substrate and the substrate adjusted this time. From the figure, it can be seen that there is little difference in adjacent luminance between the adjusted substrates. That is, it can be said that the difference in density unevenness of each pixel is small. From this, it was confirmed that density unevenness could be improved by this method. In addition, when the observation distance is 250 mm, the granularity representing the roughness is D = 0.4276 for the normal error diffused, but in this method, D = 0.3874, which indicates that the granularity can be improved. From this, it was confirmed that this was a system with reduced roughness.

  In this way, an effective nozzle that ejects ink is selected from the parameter information of the nozzle and the substrate, the frequency for increasing or decreasing the number of ink drops ejected from the effective nozzle is determined for each pixel, and the actual ejection is performed for each pixel. By increasing / decreasing the number of drops to increase the width, it is possible to obtain a substrate that has no density unevenness and roughness that has conventionally occurred between the main scanning directions and that does not generate unevenness even in a laminated substrate in a short time with high accuracy. I was able to get things.

  DESCRIPTION OF SYMBOLS 1 ... Translucent substrate, 2 ... Pixel electrode, 3 ... Partition, 4 ... Hole transport layer, 5 ... Electron block layer, 6 ... Organic light emitting layer, 7 ... Cathode layer, 8 ... Glass cap, 9 ... Adhesive, DESCRIPTION OF SYMBOLS 11 ... Partition pattern, 12 ... Pixel, 31 ... Nozzle, 42 ... Nozzle head, 43 ... Nozzle head, 44-1 ... Inkjet nozzle head, 44-2 ... Inkjet nozzle head, 44-3 ... Inkjet nozzle head, 44-4 Inkjet nozzle head, 44-5 ... Inkjet nozzle head, 46 ... Organic light emitting layer R head, 47 ... Organic light emitting layer G head, 48 ... Organic light emitting layer B head, 50 ... Substrate, 51 ... Pattern formation by ink jet nozzle head 101 52, a region to be patterned by the inkjet nozzle head 102, 53 ... an inkjet nozzle An area to be patterned by the head 103, 54 ... an area to be patterned by the inkjet nozzle head 104, 55 ... an area to be patterned by the inkjet nozzle head 105, 60 ... an inkjet nozzle head unit, 61 ... a table, 62 ... an inkjet nozzle Head, 64... Inkjet pattern forming apparatus main body, 65... Inkjet nozzle head unit controller, 82... R pixel for measuring film thickness, 90... Substrate, 91.

Claims (7)

Using at least one inkjet head having a plurality of nozzles on a substrate provided with a discharge region surrounded by a plurality of matrix-like partition walls, ink was discharged from the nozzles according to discharge pattern data to eliminate density unevenness. In an inkjet pattern forming apparatus for forming at least one functional layer,
When forming the functional layer,
The ejection pattern data is calculated by reference data for making the average amount of ink in an opening existing in an arbitrary area having a predetermined area uniform, an adjustment table for adjusting the reference data, and a multi-value error diffusion method. Process,
An inkjet pattern forming apparatus comprising:   In the adjustment table, an opening for adjusting the liquid volume by ± α and an opening for not adjusting the liquid volume are arranged in a 45-degree direction, and ± α is vertically and horizontally opened for the liquid volume adjustment. 2. The ink jet pattern forming apparatus according to claim 1, wherein the data is arranged so as to be sandwiched, and data for the entire surface of the substrate opening is arranged in a repetitive pattern.   The amount of liquid allocated from the target opening to the surrounding openings by the multilevel error diffusion method is the remainder obtained by dividing the ink amount of the target opening determined by the reference data and the adjustment table by the unit drop amount of the inkjet head. The inkjet pattern forming apparatus according to claim 1, wherein the determination is performed by diffusing with an error diffusion filter weighted according to a direction viewed from the opening of interest.   When forming a plurality of functional layers, the increase / decrease position of the drop amount in the ejection pattern data is adjusted so that it does not coincide with the allocation position of the functional layer formed in the lower layer as much as possible. The inkjet pattern forming apparatus according to any one of claims 1 to 3.   The increase / decrease position of the drop amount in the ejection pattern data is adjusted so that the variation in film thickness of each pixel of the functional layer stacked in the main scanning direction of the substrate is reduced. Item 5. The inkjet pattern forming apparatus according to any one of Items 1 to 4.   6. The inkjet pattern forming apparatus according to claim 1, wherein at least one of the functional layers to be laminated is a self-luminous member that emits light when a current is applied.   An organic functional element manufacturing method for forming a plurality of organic functional layers on a substrate, wherein the organic functional layer is formed by the ink jet pattern forming apparatus according to any one of claims 1 to 5. A method for producing an organic functional element.

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