JP2013165023A - Ink jet device and organic el display panel manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL display panel manufacturing method, with which it is possible to reduce variation in droplet application amount between ink jet heads, and an ink jet device used in the manufacturing.SOLUTION: An ink jet device includes: a first nozzle group and a second nozzle group that are parallelly disposed adjacent to each other and in each of which a plurality of nozzles that each include a piezoelectric element for droplet discharge are disposed in a line manner; and a discharge control part for giving drive signals to the piezoelectric elements, wherein the discharge control part applies a second drive signal Vm1 for droplet non-discharge to each of the piezoelectric elements of at least a part of the nozzles 3030ab of the second nozzle group, applies a first drive signal Vh for the droplet discharge at first timings, at which droplets should be discharged, to each of the piezoelectric elements of the nozzles 3030aa of the first nozzle group, and applies neither the first drive signal nor the second drive signal at second timings, at which the droplet discharge should be prohibited, and at third timings that are neither the first timings nor the second timings.

Description

  The present invention relates to an inkjet apparatus used for manufacturing an organic EL display panel and a method for manufacturing the organic EL display panel.

In recent years, organic EL display panels in which organic EL elements are arranged on a substrate as a display device are becoming widespread. The organic EL display panel has characteristics such as high visibility because it uses an organic EL element that performs self-emission, and excellent impact resistance because it is a complete solid element.
The organic EL element is a current-driven light-emitting element, and is configured by laminating an organic light-emitting layer or the like that performs an electroluminescence phenomenon due to carrier recombination between an anode and a cathode electrode pair. In the organic EL display panel, the organic EL element corresponding to each color of red (R), green (G), and blue (B) is a subpixel, and a combination of three subpixels of R, G, and B is 1. It corresponds to a pixel (one pixel).

  As such an organic EL display panel, one in which an organic light emitting layer of an organic EL element is formed by a wet process (application process) such as an ink jet method is known (for example, Patent Document 1). In the ink jet method, the ink jet head is scanned with respect to openings (corresponding to the organic light emitting layer forming region) provided in a matrix in the partition layer on the substrate. And the droplet of the ink containing the organic material and solvent which comprise an organic light emitting layer with respect to each opening part is discharged from the some nozzle with which an inkjet head is equipped.

  In order to improve ink application efficiency, a method of scanning a head portion in which a plurality of inkjet heads are arranged in a line is used.

JP 2005-322656 A JP 2008-218250 A JP 2004-111074 A

  Ink jet heads may have individual differences in ink discharge easiness (ease of ink ejection) due to manufacturing errors and the like. For example, if there is a difference in ink discharge easiness between adjacent ink jet heads, a variation in the amount of ink applied to the ink jet head unit occurs when the head portion is scanned. As a result, the light emission luminance of the organic EL display panel is striped. Variation may occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an inkjet device, a method for manufacturing an organic EL display panel, and the like that can reduce variations in ink application amount.

  An ink jet apparatus according to an aspect of the present invention is a first nozzle in which a plurality of nozzles each including a nozzle hole and a piezoelectric element for discharging a liquid material as droplets from the nozzle hole are arranged in a row. A plurality of different nozzles having the same configuration as the nozzles of the first nozzle group, and a second nozzle group arranged in parallel adjacent to the first nozzle group, And an ejection control unit that applies a drive signal for driving the piezoelectric element to the piezoelectric element, wherein the piezoelectric element ejects a droplet when the first drive signal is applied. When the two drive signals are applied, the liquid droplets are not discharged, and the discharge control unit causes the first liquid droplets to be discharged to each of the piezoelectric elements of the nozzles of the first nozzle group. When it is time The first driving signal is applied, and the first driving is performed at the second timing when the ejection of the droplet should be prohibited and the third timing which is neither the first timing nor the second timing. No signal or the second drive signal is applied, and the second drive signal is applied to each of the piezoelectric elements of at least some of the nozzles of the second nozzle group.

  In the ink jet device according to one aspect of the present invention, the first drive signal is applied to the piezoelectric elements of the first nozzle group at the first timing at which the droplets should be ejected, and the droplets are ejected from the nozzle holes. Thus, desired ink (liquid material) application is performed. A second drive signal that does not eject droplets is applied to the piezoelectric elements of at least some of the nozzles of the second nozzle group.

Although the second drive signal does not cause the piezoelectric element to eject droplets, the piezoelectric element is expected to generate heat due to the applied voltage, so that the heat generation can be influenced on the liquid.
That is, due to the heat generated by the second nozzle group to which the second drive signal is applied, the temperature of the liquid material in the adjacent first nozzle group can be raised to increase the discharge ease of the first nozzle group.

  Thereby, according to the ink jet apparatus according to the aspect of the present invention, it is possible to reduce variations in the amount of ink applied between ink jet heads (nozzle groups) adjacent in the sub-scanning direction.

It is a partial expanded sectional view which shows typically schematic structure of an organic electroluminescence display panel. It is a schematic diagram which shows the shape of the partition layer of an organic electroluminescence display panel. It is a figure which shows the example of a manufacturing process of an organic electroluminescence display panel. It is a figure which shows the example of a manufacturing process of an organic electroluminescence display panel. 1 is a diagram schematically showing a main configuration of an ink jet apparatus according to Embodiment 1. FIG. 2 is a functional block diagram of the ink jet apparatus according to Embodiment 1. FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically schematic structure of the inkjet head of the inkjet apparatus which concerns on Embodiment 1, Comprising: (a) is a partially notched perspective view which shows schematic structure of an inkjet head, (b) is a nozzle of FIG. It is sectional drawing which shows schematic structure. It is a figure which shows typically the positional relationship of the application | coating target board | substrate which concerns on Embodiment 1, and a head part. (A) is a figure which shows the waveform of a 1st drive signal typically, (b) is a figure which shows the waveform of a 2nd drive signal typically. (A) is a table | surface which shows the relationship between discharge easiness and the peak voltage of a 2nd drive signal, (b) is a figure which shows the magnitude relationship of each peak voltage of a 2nd drive signal. It is a figure which shows typically the positional relationship of the opening part and head part in the time t1. It is a figure which shows typically the positional relationship of the opening part and head part in the time t2. It is a figure which shows typically the positional relationship of the opening part and head part in the time t3. It is a figure which shows typically the positional relationship of the opening part and head part in the time t4. It is a figure which shows typically the positional relationship of the opening part and head part in the time t5. It is a figure which shows typically the positional relationship of the opening part and head part in the time t6. It is a figure which shows typically the positional relationship of the opening part and head part in the time t7. It is a figure which shows typically the positional relationship of the opening part and head part in the time t8. It is a figure which shows typically the positional relationship of the opening part and head part in the time t9. It is a figure which shows typically the positional relationship of the opening part and head part in the time t10. It is a figure which shows typically the positional relationship of the opening part and head part in the time t11. It is a figure which shows typically the positional relationship of the opening part and head part in the time t12. It is a timing chart which shows the drive signal applied to the piezoelectric element of each nozzle of head group HG301a. It is a timing chart which shows the drive signal applied to the piezoelectric element of each nozzle of head group HG301b. FIG. 4 is a diagram schematically illustrating a main configuration of an ink jet apparatus according to a second embodiment. 4 is a partially cutaway perspective view schematically showing a schematic configuration of an inkjet head of an inkjet apparatus according to Embodiment 2. FIG. It is a figure which shows typically the positional relationship of the application | coating target board | substrate which concerns on Embodiment 2, and a head part. 10 is a timing chart showing drive signals applied to piezoelectric elements of nozzles of a head group HG301b in an inkjet apparatus according to Modification Example 1. FIG. 10 is a timing chart showing drive signals applied to piezoelectric elements of respective nozzles of a head group HG301a in an inkjet device according to Modification 2. It is a figure which shows the positional relationship of the application | coating target board | substrate which concerns on the modification 3, and a head part. It is a figure which shows the positional relationship of the application | coating target board | substrate which concerns on the modification 4, and a head part. It is a figure which shows the positional relationship of the application | coating target board | substrate which concerns on the modification 5, and a head part. It is a figure which shows the positional relationship of the application | coating target board | substrate which concerns on the modification 6, and a head part.

<< Outline of One Embodiment of the Present Invention >>
An inkjet apparatus according to an aspect of the present invention is a first nozzle in which a plurality of nozzles each including a nozzle hole and a piezoelectric element for discharging a liquid material as droplets from the nozzle hole are arranged in a row. A plurality of different nozzles having the same configuration as the nozzles of the first nozzle group, and a second nozzle group arranged in parallel adjacent to the first nozzle group, And an ejection control unit that applies a drive signal for driving the piezoelectric element to the piezoelectric element, wherein the piezoelectric element ejects a droplet when the first drive signal is applied. When the two drive signals are applied, the liquid droplets are not discharged, and the discharge control unit causes the first liquid droplets to be discharged to each of the piezoelectric elements of the nozzles of the first nozzle group. When it is time The first driving signal is applied, and the first driving is performed at the second timing when the ejection of the droplet should be prohibited and the third timing which is neither the first timing nor the second timing. No signal or the second drive signal is applied, and the second drive signal is applied to each of the piezoelectric elements of at least some of the nozzles of the second nozzle group.

  Although the second drive signal does not cause the piezoelectric element to eject droplets, the piezoelectric element generates heat by the applied voltage and can heat the liquid. Accordingly, by applying the second drive signal to the piezoelectric element of the second nozzle group adjacent to the first nozzle group, which is less likely to discharge the liquid material, the temperature of the second nozzle group is raised and the heat is adjacent. By conducting to the first nozzle group, the temperature of the liquid material of the first nozzle group can be raised to enhance the discharge easiness.

Therefore, according to the ink jet device according to one aspect of the present invention, the difference in ink discharge easiness between the ink jet heads (nozzle groups) adjacent to each other in the sub-scanning direction can be reduced, and the variation in the belt-like ink application amount can be made uniform. Is possible.
Further, in a specific aspect of the ink jet device according to an aspect of the present invention, the first timing or the third timing is set for each of the piezoelectric elements of at least some of the nozzles of the second nozzle group. In some cases, the second drive signal is applied.

Further, in a specific aspect of the ink jet device according to one aspect of the present invention, the discharge control unit increases the peak voltage of the second drive signal as the ink discharge easiness of the first nozzle group is lower. Features.
Further, in a specific aspect of the ink jet device according to one aspect of the present invention, the ejection control unit increases the frequency of the second drive signal as the ink ejection easiness of the first nozzle group is lower. And

Moreover, in a specific aspect of the ink jet apparatus according to an aspect of the present invention, the discharge control unit is configured such that the lower the ink discharge easiness of the first nozzle group, the more the plurality of nozzles constituting the second nozzle group. The second drive signal is applied to the piezoelectric elements of more nozzles.
Moreover, in a specific aspect of the ink jet apparatus according to one aspect of the present invention, the first nozzle group and the second nozzle group are respectively disposed in separate ink jet heads.

Further, in a specific aspect of the ink jet apparatus according to one aspect of the present invention, the first nozzle group and the second nozzle group are arranged in one ink jet head.
Moreover, in a specific aspect of the ink jet apparatus according to an aspect of the present invention, the liquid material is an ink containing an organic material and a solvent.

Moreover, in a specific aspect of the ink jet apparatus according to an aspect of the present invention, the discharge control unit includes piezoelectric elements of one or more nozzles of the nozzles other than the at least some nozzles of the second nozzle group. On the other hand, the first drive signal is applied at the first timing.
In the specific aspect of the ink jet device according to one embodiment of the present invention, the organic material is a material used to form an organic light emitting layer of an organic EL display panel, and the first timing is the organic The nozzle is opposed to a color application region corresponding to a material, and the second timing is a timing when the nozzle is opposed to a color application region not corresponding to the organic material. To do.

  A method for manufacturing an organic EL display panel according to an aspect of the present invention includes: a first step of preparing an EL substrate, a head unit, and a discharge control unit; and scanning the head unit in a row direction with respect to the EL substrate. A second step of ejecting the droplets from the nozzles corresponding to the openings to the openings, and the EL substrate includes a plurality of openings in a matrix form in units of pixels. A plurality of nozzles each having a nozzle hole and a piezoelectric element for discharging ink droplets containing an organic material and a solvent from the nozzle hole; The first nozzle group arranged in a row and another nozzle having the same configuration as the nozzles of the first nozzle group are arranged in a plurality of rows and arranged in parallel adjacent to the first nozzle group. A second nozzle group, and The discharge control unit gives a drive signal for driving the piezoelectric element to the piezoelectric element, and in the second step, the discharge control unit applies the liquid to each of the piezoelectric elements of the nozzles of the first nozzle group. When it is the first timing at which droplets are to be ejected, the first drive signal is applied, and the second timing at which ejection of the droplets is prohibited and the second timing even at the first timing. However, at the third timing, neither the first drive signal nor the second drive signal is applied, and the second drive is performed for each of the piezoelectric elements of at least some of the nozzles of the second nozzle group. A signal is applied.

Further, in a specific aspect of the method for manufacturing an organic EL display panel according to an aspect of the present invention, the first timing or the first timing is applied to each piezoelectric element of at least some of the nozzles of the second nozzle group. When the timing is 3, the second drive signal is applied.
Further, in a specific aspect of the method for manufacturing an organic EL display panel according to one aspect of the present invention, in the second step, the discharge control unit may reduce the first ink group as the ink discharge easiness is lower. 2 The peak voltage of the drive signal is increased.

Further, in a specific aspect of the method for manufacturing an organic EL display panel according to one aspect of the present invention, in the second step, the discharge control unit may reduce the first ink group as the ink discharge easiness is lower. (2) The frequency of the drive signal is increased.
Further, in a specific aspect of the method for manufacturing an organic EL display panel according to one aspect of the present invention, in the second step, the discharge control unit may reduce the first ink group as the ink discharge easiness is lower. The second drive signal is applied to the piezoelectric elements of more nozzles among the plurality of nozzles constituting the two nozzle group.

Further, in a specific aspect of the method for manufacturing an organic EL display panel according to an aspect of the present invention, in the first step, the first nozzle group and the second nozzle group are arranged on separate adjacent inkjet heads. It is provided.
Moreover, in a specific aspect of the method for manufacturing an organic EL display panel according to an aspect of the present invention, in the first step, the first nozzle group and the second nozzle group are disposed in one inkjet head. It is characterized by.

Moreover, in a specific aspect of the method for manufacturing an organic EL display panel according to one embodiment of the present invention, the organic material is a material used for forming an organic light emitting layer.
Moreover, in the specific aspect of the manufacturing method of the organic EL display panel which concerns on 1 aspect of this invention, in the said 2nd process, the said discharge control part is nozzles other than the said at least one part nozzle of the said 2nd nozzle group. The first drive signal is applied to each of the piezoelectric elements of one or a plurality of nozzles at the first timing.

  Moreover, in the specific aspect of the manufacturing method of the organic electroluminescent display panel which concerns on 1 aspect of this invention, the said organic material is a material used in order to form an organic light emitting layer, The said 1st timing is the said organic The timing when the nozzle faces the opening of the color corresponding to the material, and the second timing is the timing when the nozzle faces the opening of the color not corresponding to the organic material. Features.

<< Embodiment 1 >>
[overall structure]
FIG. 1 is a partial cross-sectional view showing a configuration of an organic EL display panel 100 according to Embodiment 1. The organic EL display panel 100 is a so-called top emission type in which the upper side of FIG.

  As shown in FIG. 1, a TFT layer 2, a feeding electrode 3, an interlayer insulating film 4, a pixel electrode 6, and a hole injection layer 9 are sequentially stacked on a substrate (EL substrate) 1. On the hole injection layer 9, a partition wall layer 7 in which a plurality of openings 17 serving as a region where the organic light emitting layer 11 is formed is provided. Inside the opening 17, a hole transport layer 10, an organic light emitting layer 11, an electron transport layer 12, an electron injection layer 13, and a counter electrode 14 are sequentially stacked.

<Substrate, TFT layer, feeding electrode>
The substrate 1 is a rear substrate in the organic EL display panel 100, and a TFT layer 2 including a TFT (thin film transistor) for driving the organic EL display panel 100 by an active matrix method is formed on the surface thereof. On the upper surface of the TFT layer 2, a feeding electrode 3 for supplying electric power to each TFT from the outside is formed.

<Interlayer insulation film>
The interlayer insulating film 4 is provided in order to adjust the surface step generated by the TFT layer 2 and the power supply electrode 3 to be flat, and is made of an organic material having excellent insulating properties.
<Contact hole>
The contact hole 5 is provided to electrically connect the power supply electrode 3 and the pixel electrode 6 and is formed from the front surface to the back surface of the interlayer insulating film 4. The contact holes 5 are formed so as to be positioned between the openings 17 arranged in the column direction, and are configured to be covered with the partition wall layer 7. When the contact hole 5 is not covered with the partition wall layer 7, the presence of the contact hole 5 does not cause the organic light emitting layer 11 to be a flat layer, which causes uneven light emission. In order to avoid this, the above configuration is adopted.

<Pixel electrode>
The pixel electrode 6 is an anode, and is formed for each organic light emitting layer 11 formed in the opening 17. Since the organic EL display panel 100 is a top emission type, a light reflective material is selected as the material of the pixel electrode 6.
<Hole injection layer>
The hole injection layer 9 is provided for the purpose of promoting the injection of holes from the pixel electrode 6 to the organic light emitting layer 11.

<Partition wall layer>
When the organic light emitting layer 11 is formed, the partition layer 7 is mixed with an organic light emitting layer material corresponding to each color of red (R), green (G), and blue (B) and an ink (liquid) containing a solvent. It serves to prevent this.
The partition layer 7 provided so as to cover the contact hole 5 has a trapezoidal cross section along the XY plane or the YZ plane as a whole, but the position corresponding to the contact hole 5 Then, the shape of the partition wall layer material is contracted and depressed. Hereinafter, the depressed portion is referred to as a recessed portion 8.

FIG. 2 is a diagram schematically showing the shape of the partition layer 7 when the organic EL display panel 100 is viewed from the display surface side. For convenience of explanation, a hole transport layer 10, an organic light emitting layer 11, an electron transport layer 12, The state where the electron injection layer 13 and the counter electrode 14 are removed is shown. Further, the partial cross-sectional view of FIG. 1 corresponds to the AA ′ cross-sectional view of FIG. 2, and hereinafter, the X direction is the row direction and the Y direction is the column direction.
As shown in FIG. 2, the openings 17 provided in the partition wall layer 7 are arranged in a matrix (in the XY direction) in units of pixels. The opening 17 is a region where the organic light emitting layer 11 is formed, and the arrangement and shape of the organic light emitting layer 11 are defined by the arrangement and shape of the opening 17. The opening 17 has a long shape having a long side in the column (Y) direction. For example, the side along the row (X) direction is about 50 to 100 [μm], and the side along the column (Y) direction is It is formed with a size of about 150 to 300 [μm].

  The opening 17 has openings 17R, 17G, and 17B corresponding to R, G, and B colors. The organic light emitting layer 11 corresponding to R is formed in the opening 17R, G in the opening 17G, and B in the opening 17B. The openings 17R, 17G, and 17B are sub-pixels, and a combination of the three sub-pixels of the openings 17R, 17G, and 17B corresponds to one pixel (one pixel). The openings 17 are arranged for each column in R, G, and B color units, and the openings 17 belonging to the same column are openings corresponding to the same color.

The contact holes 5 are located between the openings 17 arranged in the column direction, that is, below the partition wall layer 7. Although it has been described above that the pixel electrode 6 is formed for each organic light emitting layer 11 formed in the opening 17, this means that the pixel electrode 6 is provided for each sub-pixel. To do.
<Hole transport layer>
Returning to the partial cross-sectional view of FIG. 1, the hole transport layer 10 has a function of transporting holes injected from the pixel electrode 6 to the organic light emitting layer 11.

<Organic light emitting layer>
The organic light emitting layer 11 is a portion that emits light by recombination of carriers (holes and electrons), and is configured to include an organic material corresponding to one of R, G, and B colors. The organic light emitting layer 11 containing an organic material corresponding to R is formed in the opening 17R, an organic material corresponding to G in the opening 17G, and an organic material corresponding to B in the opening 17B.

<Electron transport layer>
The electron transport layer 12 has a function of transporting electrons injected from the counter electrode 14 to the organic light emitting layer 11.
<Electron injection layer>
The electron injection layer 13 has a function of promoting injection of electrons from the counter electrode 14 to the organic light emitting layer 11.

<Counter electrode>
The counter electrode 14 is a cathode. Since the organic EL display panel 100 is a top emission type, a light transmissive material is selected as the material of the counter electrode 14.
<Others>
Although not shown in FIG. 1, a sealing layer is provided on the counter electrode 14 for the purpose of preventing the organic light emitting layer 11 from being deteriorated by contact with moisture, air, or the like. Since the organic EL display panel 100 is a top emission type, a light transmissive material such as SiN (silicon nitride) or SiON (silicon oxynitride) is selected as the material of the sealing layer.

In addition, all the organic light emitting layers 11 formed in each opening part 17 can also be made into the organic light emitting layer of the same color.
<Material of each layer>
Next, the material of each layer demonstrated above is illustrated. Needless to say, each layer can be formed using materials other than those described below.

Substrate 1: alkali-free glass, soda glass, non-fluorescent glass, phosphate glass, borate glass, quartz, acrylic resin, styrene resin, polycarbonate resin, epoxy resin, polyethylene, polyester, silicone resin, alumina, etc. Interlayer insulating film 4: Polyimide resin, acrylic resin Pixel electrode 6: Ag (silver), Al (aluminum), alloy of silver, palladium and copper, alloy of silver, rubidium and gold, aluminum alloy , Mo (molybdenum), MoCr (alloy of molybdenum and chromium), MoW (alloy of molybdenum and tungsten), NiCr (alloy of nickel and chromium)
A known transparent conductive film may be provided on the surface of the pixel electrode 6. As a material of the transparent conductive film, for example, indium tin oxide (ITO) or indium zinc oxide (IZO) can be used.

Partition layer 7: acrylic resin, polyimide resin, novolak type phenol resin Organic light emitting layer 11: oxinoid compound, perylene compound, coumarin compound, azacoumarin compound, oxazole compound, oxadiazole compound, perinone compound, pyrrolopyrrole compound, naphthalene compound , Anthracene compound, fluorene compound, fluoranthene compound, tetracene compound, pyrene compound, coronene compound, quinolone compound and azaquinolone compound, pyrazoline derivative and pyrazolone derivative, rhodamine compound, chrysene compound, phenanthrene compound, cyclopentadiene compound, stilbene compound, diphenylquinone compound , Styryl compounds, butadiene compounds, dicyanomethylenepyran compounds, dicyanomethylenethiopyran compounds, Fluorescein compound, pyrylium compound, thiapyrylium compound, serenapyrylium compound, telluropyrylium compound, aromatic ardadiene compound, oligophenylene compound, thioxanthene compound, cyanine compound, acridine compound, metal complex of 8-hydroxyquinoline compound, 2-bipyridine compound Fluorescent substances such as metal complexes, Schiff salts and group III metal complexes, oxine metal complexes, rare earth complexes (all described in JP-A-5-163488)
Hole injection layer 9: triazole derivative, oxadiazole derivative, imidazole derivative, polyarylalkane derivative, pyrazoline derivative and pyrazolone derivative, phenylenediamine derivative, arylamine derivative, amino-substituted chalcone derivative, oxazole derivative, styrylanthracene derivative, fluorenone derivative , Hydrazone derivatives, stilbene derivatives, porphyrin compounds, aromatic tertiary amine compounds, styrylamine compounds, butadiene compounds, polystyrene derivatives, hydrazone derivatives, triphenylmethane derivatives, tetraphenylbenzine derivatives (all disclosed in JP-A-5-163488) Metal oxide such as MoOx (molybdenum oxide), WOx (tungsten oxide) or MoxWyOz (molybdenum-tungsten oxide). , Metal nitride or metal oxynitride hole transport layer 10: triazole derivative, oxadiazole derivative, imidazole derivative, polyarylalkane derivative, pyrazoline derivative and pyrazolone derivative, phenylenediamine derivative, arylamine derivative, amino-substituted chalcone derivative, Oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, polyphyllin compounds, aromatic tertiary amine compounds, styrylamine compounds, butadiene compounds, polystyrene derivatives, hydrazone derivatives, triphenylmethane derivatives, tetraphenylbenzine derivatives ( (All are described in JP-A-5-163488)
Electron transport layer 12: nitro-substituted fluorenone derivative, thiopyrandioxide derivative, difequinone derivative, perylenetetracarboxyl derivative, anthraquinodimethane derivative, fluorenylidenemethane derivative, anthrone derivative, oxadiazole derivative, perinone derivative, quinoline complex derivative (All described in JP-A-5-163488), phosphorus oxide derivatives, triazole derivatives, todiazine derivatives, silole derivatives, dimesityl boron derivatives, triaryl boron derivatives Electron injection layer 13: lithium, barium, calcium, potassium, cesium, sodium Low work function metal such as rubidium, low work function metal salt such as lithium fluoride, low work function metal oxide such as barium oxide Counter electrode 14: ITO (indium tin oxide) IZO (indium zinc oxide)
The configuration of the organic EL display panel 100 has been described above. Next, a method for manufacturing the organic EL display panel 100 is illustrated.

[Production method]
Here, the whole manufacturing method of the organic EL display panel 100 will be exemplified first. Then, the detail is demonstrated about the application | coating process in a manufacturing method.
<Outline>
First, the substrate 1 on which the TFT layer 2 and the feeding electrode 3 are formed is prepared (FIG. 3A).

  Thereafter, an interlayer insulating film 4 having a thickness of about 4 [μm] is formed on the TFT layer 2 and the feeding electrode 3 using an organic material having excellent insulating properties based on a photoresist method. At this time, the contact holes 5 are formed in accordance with the positions between the openings 17 adjacent in the column direction (FIG. 3B). At this time, the interlayer insulating film 4 and the contact hole 5 can be formed simultaneously by performing a photoresist method using a desired pattern mask. Of course, the method of forming the contact hole 5 is not limited to this. For example, after the interlayer insulating film 4 is uniformly formed, the interlayer insulating film 4 at a predetermined position can be removed to form the contact hole 5.

Subsequently, a pixel electrode 6 made of a metal material having a thickness of about 150 [nm] is formed for each sub-pixel while being electrically connected to the power supply electrode 3 based on a vacuum deposition method or a sputtering method. Subsequently, the hole injection layer 9 is formed based on the reactive sputtering method (FIG. 3C).
Next, the partition layer 7 is formed based on a photolithography method. First, as the partition layer material, a pasty partition layer material containing a photosensitive resist is prepared. The partition layer material is uniformly applied on the hole injection layer 9. A mask formed in the pattern of the opening 17 shown in FIG. Subsequently, exposure is performed on the mask to form a partition wall layer pattern. Thereafter, excess partition wall layer material is washed out with an aqueous or non-aqueous etching solution (developer). Thereby, patterning of the partition wall layer material is completed. As described above, the opening 17 serving as the organic light emitting layer forming region is defined, and the recess 8 is formed on the upper surface between the openings 17 adjacent in the column direction. (FIG. 3D). When the contact hole 5 is formed as in the present embodiment, since the partition wall material usually enters the contact hole 5, the recess 8 is naturally formed. For this reason, the process for forming the hollow part 8 separately is unnecessary, and it is advantageous on production cost and manufacturing efficiency.

In the step of forming the partition wall layer 7, the surface of the partition wall layer 7 is further subjected to a predetermined surface in order to adjust the contact angle of the partition wall layer 7 with respect to the ink applied to the opening 17 or to impart water repellency to the surface. Surface treatment may be performed with an alkaline solution, water, an organic solvent, or the like, or plasma treatment may be performed.
Next, the organic material and solvent which comprise the positive hole transport layer 10 are mixed by the predetermined ratio, and the positive hole transport layer ink is prepared. This ink is supplied to each inkjet head 301, and droplets 18 made of hole transport layer ink are ejected from nozzles 3030 (see FIG. 7) corresponding to the openings 17 based on the coating process (FIG. 3 ( e)). Thereafter, the solvent contained in the ink is evaporated and dried, and heated and fired as necessary to form the hole transport layer 10 (FIG. 4A).

  Next, an organic material constituting the organic light emitting layer 11 and a solvent are mixed at a predetermined ratio to prepare an organic light emitting layer ink. This ink is supplied to the inkjet head 301, and based on the coating process, droplets 19 made of organic light emitting layer ink are ejected from the nozzles 3030 corresponding to the openings 17 and the depressions 8 (FIG. 4B). Thereafter, the solvent contained in the ink is evaporated and dried, and the organic light emitting layer 11 is formed by heating and baking as required (FIG. 4C).

  Next, a material constituting the electron transport layer 12 is formed on the surface of the organic light emitting layer 11 based on a vacuum deposition method. Thereby, the electron transport layer 12 is formed. Subsequently, the material for forming the electron injection layer 13 is formed by a method such as vapor deposition, spin coating, or casting to form the electron injection layer 13. Then, using a material such as ITO or IZO, a film is formed by vacuum deposition, sputtering, or the like. Thereby, the counter electrode 14 is formed (FIG. 4D).

Although not shown, a sealing layer is formed on the surface of the counter electrode 14 by forming a light transmissive material such as SiN or SiON by sputtering, CVD, or the like.
The organic EL display panel 100 is completed through the above steps.
<Application process>
Hereinafter, in particular, a coating process when forming the organic light emitting layer 11 will be described in detail. First, an inkjet device used in the coating process will be described.

(Inkjet device)
FIG. 5 is a diagram illustrating a main configuration of the inkjet apparatus 1000 according to the first embodiment. FIG. 6 is a functional block diagram of the ink jet apparatus 1000.
As shown in FIGS. 5 and 6, the inkjet apparatus 1000 includes an inkjet table 20, a head unit 30, and a control device (PC) 15.

  As shown in FIG. 6, the control device 15 includes a CPU 150, a storage unit 151 (including a large-capacity storage unit such as an HDD), a display unit (display) 153, and an input unit 152. Specifically, the control device 15 can be a personal computer (PC). The storage unit 151 stores a control program and the like for driving the inkjet table 20 and the head unit 30 connected to the control device 15. When the ink jet apparatus 1000 is driven, the CPU 150 performs predetermined control based on an instruction input by the operator through the input unit 152 and each control program stored in the storage unit 151.

(Inkjet table)
As shown in FIG. 5, the ink jet table 20 is a so-called gantry work table, and a gantry section (moving stand) is arranged on a base table so as to be movable along a pair of guide shafts.
As a specific configuration, columnar stands 201 </ b> A, 201 </ b> B, 202 </ b> A, 202 </ b> B are arranged at the four corners of the upper surface of the plate-like base 200. In the inner region surrounded by these stands 201A, 201B, 202A, 202B, the ejection characteristics are stabilized by ejecting ink immediately before application and a fixed stage ST for placing a substrate to be applied. For this purpose, an ink pan (dish container) IP is provided.

  Further, guide shafts 203A and 203B are supported in parallel on the stands 201A, 201B, 202A and 202B along the longitudinal (Y) direction of the base 200. Linear motor portions 204 and 205 are inserted through the guide shafts 203A and 203B, and a gantry portion 210 is mounted so as to bridge the guide shafts 203A and 203B with respect to the linear motor portions 204 and 205. With this configuration, when the ink jet apparatus 1000 is driven, the pair of linear motor units 204 and 205 is driven so that the gantry unit 210 can slide along the longitudinal direction (Y-axis direction) of the guide shafts 203A and 203B. Reciprocate.

  The gantry unit 210 is provided with a moving body (carriage) 220 made of an L-shaped pedestal. The moving body 220 is provided with a servo motor unit (moving body motor) 221, and a gear (not shown) is disposed at the tip of the shaft of each motor. The gear is fitted in a guide groove 211 formed along the longitudinal direction (X direction) of the gantry unit 210. Inside the guide groove 211, a fine rack is formed along the longitudinal direction. Since the gear meshes with the rack, when the servo motor unit 221 is driven, the moving body 220 moves precisely and reciprocally along the X-axis direction by a so-called pinion rack mechanism.

  Here, since the moving body 220 is equipped with the head unit 30, the gantry unit 210 is moved along the longitudinal direction of the guide shafts 203A and 203B while the moving body 220 is fixed to the gantry unit 210. Further, by moving the moving body 220 along the longitudinal direction of the gantry unit 210 while the gantry unit 210 is stopped, the head unit 30 can be scanned with respect to the application target substrate. The main scanning direction of the head unit 30 is the row (Y-axis) direction, and the sub-scanning direction is the column (X-axis) direction.

  The linear motor units 204 and 205 and the servo motor unit 221 are each connected to a control unit 213 for directly controlling driving, and the control unit 213 is connected to the CPU 150 in the control device 15. When the inkjet apparatus 1000 is driven, the CPU 150 that has read the control program controls each drive of the linear motor units 204 and 205 and the servo motor unit 221 via the control unit 213 (see FIG. 6).

(Inkjet head)
The head unit 30 employs a known piezo method, and includes a plurality of inkjet heads 301 and a main body unit 302. The ink jet head 301 is fixed to the moving body 220 via the main body 302. In this embodiment, one set of inkjet heads 301 is held by one holder 303, and four sets of inkjet heads 301 are fixed to the moving body 220 via the main body 302. The main body 302 has a built-in servo motor 304 (see FIG. 6). By rotating the servo motor 304, the angle formed by the longitudinal direction of the inkjet head 301 and the X axis of the fixed stage ST is adjusted. . In the present embodiment, adjustment is made so that the longitudinal direction of the inkjet head 301 and the Y axis intersect at a predetermined angle.

  7A is a partially cutaway perspective view showing a schematic configuration of the inkjet head 301, and FIG. 7B is a cross-sectional view showing a schematic configuration of the nozzle 3030 of the inkjet head 301. FIG. It is BB 'arrow sectional drawing in (a). As shown in FIGS. 7A and 7B, the inkjet head 301 includes a nozzle plate 301i having a plurality of nozzle holes 3031 through which droplets D are discharged, and a cavity 301e in which the plurality of nozzle holes 3031 communicate with each other. A cavity plate 301c having partitioning walls 301d and a diaphragm 301h having piezoelectric elements 3010 as driving means corresponding to the respective cavities 301e are sequentially stacked and bonded.

  The cavity plate 301c has a partition wall 301d that divides a cavity 301e that communicates with the nozzle hole 3031 and also has flow paths 301f and 301g for filling the cavity 301e with ink. The flow paths 301f and 301g are spaces formed by a cavity plate 301c including a partition wall 301d sandwiched between a nozzle plate 301i and a vibration plate 301h. The flow path 301g serves as a reservoir for storing ink.

Ink is supplied from an ink tank or the like through a pipe, stored in a reservoir through a supply hole 301h1 provided in the vibration plate 301h, and then filled into each cavity 301e through a channel 301f.
As shown in FIG. 7B, the piezo element 3010 is a piezoelectric element in which a piezo element body 3013 is sandwiched between a pair of electrodes 3011 and 3012. When a driving voltage pulse (driving signal) is applied to the pair of electrodes 3011 and 3012 from the outside, the bonded diaphragm 301 h is deformed. As a result, the volume of the cavity 301e partitioned by the partition wall 301d is reduced, and the ink filled in the cavity 301e is pressurized so that the liquid material can be discharged as droplets D from the nozzle holes 3031. When the application of the drive voltage pulse is completed, the diaphragm 301h returns to its original state, and the volume of the cavity 301e is restored, so that ink is sucked from the reservoir into the cavity 301e. By controlling the drive voltage pulse applied to the piezo element 3010, it is possible to perform ejection control such as the amount of ink ejected from each nozzle 3030 and the ejection timing.

In FIG. 7B, a portion surrounded by a broken line is one nozzle 3030. That is, the nozzle 3030 is configured by the cavity 301e and the partition wall 301d forming the cavity 301e, the vibration plate 301h, the nozzle plate 301i, the piezo element 3010, and the nozzle hole 3031.
The inkjet head 301 includes a plurality of nozzles 3030 on the surface facing the fixed stage ST, and these nozzles 3030 are arranged in a row along the longitudinal direction of the inkjet head 301 (see FIG. 8). The ink (liquid material) supplied to the inkjet head 301 is discharged as droplets from each nozzle 3030 to the application target substrate.

  As described above, the droplet discharge operation at each nozzle 3030 is controlled by the drive voltage applied to the piezo element (piezoelectric element) 3010 provided in each nozzle 3030. The ejection control unit 300 controls the drive signal given to each piezo element 3010 to cause each nozzle 3030 to eject a droplet. Specifically, as shown in FIG. 6, the CPU 150 reads a predetermined control program from the storage unit 151 and instructs the ejection control unit 300 to apply a predetermined voltage to the target piezo element 3010.

Using the inkjet apparatus 1000 having the above-described configuration, a coating process using an inkjet method is performed. Here, the long sides of the long openings 17 are arranged so as to intersect at a predetermined angle with respect to the scanning direction (row (Y) direction) of the head unit 30 (inkjet head 301). Will be described.
(Positional relationship between the head and the opening of the substrate to be coated)
FIG. 8 is a diagram showing the positional relationship between the application target substrate and the head unit 30 in the manufacturing process of the organic EL display panel.

  In FIG. 8, a substrate to be coated is disposed on the right side of the paper surface of the head unit 30, and is a substrate in a state before the coating process, that is, a partition wall in which a plurality of openings 17 are formed in a matrix for each pixel. The substrate in a state where the layer 7 is provided is shown. In the inkjet head 301, a plurality of nozzles 3030 for ejecting ink are arranged at a predetermined nozzle pitch in the row (X) direction. At this time, the coating pitch of the nozzles 3030 can be adjusted by changing the inclination angle in the longitudinal direction of the inkjet head 301. In FIG. 8, the nozzle 3030 is represented in the form of a nozzle hole 3031. As shown in FIG. 8, in the present embodiment, six nozzles 3030 are arranged in a row along the longitudinal direction in one inkjet head 301, and five of these nozzles 3030 are one. It corresponds to the opening 17.

  In the coating process, desired ink droplets are ejected from the nozzles corresponding to the openings 17 to the openings 17 while the inkjet head 301 is scanned in the row (Y) direction. And the organic light emitting layer 11 is formed by passing through said process. At this time, the total volume of the ejected droplets needs to be uniform between the adjacent openings 17.

(Ink ejection drive signal)
In the present embodiment, one set of inkjet heads 301 is defined as one head group (HG), and the head unit 30 includes four head groups, that is, eight inkjet heads 301. Here, the drive signals applied to the respective nozzles will be described below by taking the inkjet heads 301aa and 301ab constituting the HG 301a as representative examples. The basic configuration and drive signals are the same for the ink jet heads constituting the other three HGs.

  FIG. 9A is a diagram showing a drive waveform (voltage pulse) of the first drive signal SG1 applied to the piezo element 3010 of the nozzle 3030, and FIG. 9B is a drive waveform of the second drive signal SG2. FIG. The first drive signal SG1 and the second drive signal SG2 are applied to the piezo element 3010 by the ejection control unit 300 (see FIG. 6). The piezo element 3010 ejects ink from the nozzle hole 3031 when the first drive signal SG1 is applied, but does not eject ink when the second drive signal SG2 is applied. The magnitude Vm of the peak voltage of the second drive signal SG2 is smaller than the magnitude Vh of the peak voltage of the first drive signal SG1, and Vm is, for example, about 40% of Vh.

(Ease of ink ejection and drive signal)
Piezo elements are generally known to convert some of the applied electrical energy into heat in the piezo elements. (Patent No. 3838488, JP-A-2003-65905, Keystone International Website Piezo Dictionary <URL = http: //www.keystone-intl.co.jp/products/encyclopedia/index.html>) By applying the second drive signal SG2 to the piezo element 3010, the piezo element 3010 can generate heat without discharging ink. As a result, the generated heat can be used to increase the temperature of the ink and reduce the viscosity, thereby improving the ease of ejection. The amount of heat generated increases as the peak voltage of the applied second drive signal SG2 increases. Therefore, in the present embodiment, a method for evaluating the ease of ejection of the inkjet head 301 in advance by testing and classifying it and applying the second drive signal SG2 having a peak voltage corresponding to each rank will be described. In the present embodiment, a case where classification is made into five head ranks (HR1 to HR5) will be described as an example.

  Further, in the present embodiment, out of the two inkjet heads 301 constituting one head group, ink is ejected from the nozzle 3030 of one inkjet head 301 to form an organic light emitting layer, and the other A second drive signal is applied to the piezo element 3010 of the nozzle of the inkjet head 301 to generate heat. Then, the generated heat is transferred from the other inkjet head 301 to one inkjet head 301 through the holder 303 to increase the temperature of the ink stored in the reservoir of the one inkjet head 301, thereby discharging the ink. The ease can be improved. The nozzles to which the first drive signal SG1 and the second drive signal SG2 are applied and the application timing will be described in detail in the next (Control of Drive Signal).

  FIG. 10A is a table showing the relationship between the head rank and the magnitude of the peak voltage of the second drive signal SG2. The ease of ejection is the smallest for HR5 (the least ink is most likely to be ejected) and the largest for HR1 (the most easily ejected ink). The magnitudes of the peak voltages of SG2 applied to the piezoelectric element 3010 of the inkjet head 301 classified into HR1, HR2, HR3, HR4, and HR5 are Vm1, Vm2, Vm3, Vm4, and Vm5, respectively. The lower the ease of ejection, the more the ink must be heated, so the peak voltage of SG2 to be applied is also increased. Therefore, Vm1 <Vm2 <Vm3 <Vm4 <Vm5. As the largest value of Vm5, a value that does not eject ink is selected. A positive value greater than 0 is selected as the smallest value of Vm1. Note that applying a drive signal to the piezo element 3010 of the inkjet head 301 may simply be referred to as “applying a drive signal to the inkjet head 301”.

(Control of drive signal)
FIGS. 11 to 22 schematically illustrate the positional relationship between the opening 17, the inkjet head 301, and the nozzle 3030 at times t 1 to t 12 in the step of forming the organic light emitting layer 11 using the inkjet apparatus 1000 according to the present embodiment. FIG. FIG. 23 is a timing chart showing drive signals applied to the nozzles of the inkjet heads 301aa and 301ab of the HG 301a. FIG. 24 is a timing chart showing drive signals applied to the nozzles of the inkjet heads 301ba and 301bb of the HG 301b.

In the present embodiment, inkjet heads 301aa, 301ab, 301ba, 301bb of head groups HG301a and 301b will be described as representative examples.
In the present embodiment, the case where the inkjet heads 301aa, 301ab, 301ba, 301bb of the head groups HG301a and 301b eject the material ink for forming the organic light emitting layer for G color will be described. The heads of the inkjet head 301aa The rank is HR1, and the head rank of the inkjet head 301ba is HR5.

  In the present embodiment, in the HG 301a, the first drive signal SG1 is applied to the plurality of nozzles 3030 (first nozzle group) provided in the ink jet head 301aa located in front of the head unit in the scanning direction to eject ink. The case where the second drive signal SG2 is applied to the plurality of nozzles 3030 (second nozzle group) provided in the rear inkjet head 301ab to generate heat will be described, but is not limited thereto. For example, SG2 may be applied to the nozzle 3030 of the inkjet head 301aa to generate heat, and ink may be ejected from the nozzle 3030 of the inkjet head 301ab.

  Here, the ink is ejected by applying the first drive signal SG1 at a timing when the nozzle 3030 faces the G-color opening 17G. Further, when the nozzle 3030 faces the R and B color openings 17R and 17B other than the G color, the G color ink should not be ejected. This is because when different color inks are ejected to the same opening portion 17, color mixing is caused and the image quality of the manufactured organic EL display panel is deteriorated. Accordingly, when the nozzle 3030 faces the R and B color openings 17R and 17B other than the G color, ink ejection is prohibited.

  Further, when the drive signal SG2 is applied to the nozzle 3030, the diaphragm 301h is deformed by the piezo element 3010, although the ink is not ejected. At this time, although depending on the viscosity of the ink, there is a possibility that a phenomenon that unnecessary minute ink droplets are dropped or ink droplets are scattered due to some cause. When such a phenomenon occurs at the timing when the nozzle 3030 faces the opening 17G, it does not cause a problem of color mixing, but faces the openings 17R and 17B for R and B colors. If it occurs at a certain timing, there is a possibility that a problem of color mixing may occur. Therefore, in the present embodiment, when the nozzle 3030 is opposed to the openings 17R and 17B, the second drive signal SG2 is not applied.

  The “facing” timing is used as a term that means the timing at which the ejected ink droplets land within the opening to be coated. It cannot be limited to when it exists in the position where it overlaps. That is, when the liquid droplet is dropped from the nozzle hole 3031 to the opening portion 17, the opening in a plan view is equivalent to the distance moved in the moving direction of the head portion 30 due to the influence of the inertial force due to the movement of the head portion 30. This is the timing at which the nozzle 3030 is present at a position shifted rearward in the movement direction of the head unit 30 from the position of the head portion.

  As shown in FIG. 11, at time t1, the nozzle 3030ab2 of the inkjet head 301ab is located in a region facing the opening 17R. From the time when the movement (scanning) of the head unit 30 is started (T = t0) to T = t1, each nozzle 3030 of the inkjet head 301aa has reached the region facing the opening 17G. Therefore, neither the first drive signal SG1 nor the second drive signal SG2 is applied. Since each nozzle 3030 of the inkjet head 301ab is not in a position facing any opening 17 until immediately before T = t1, SG2 is applied to the nozzles 3030ab1 to 3030ab6 from t0 to immediately before t1. At this time, since the head rank of the inkjet head 301aa belonging to the same head group is HR1, Vm of SG2 applied to each nozzle 3030 of the inkjet head 301ab is Vm1. At time t1, the nozzle 3030ab2 enters the region facing the opening 17R, and the application of SG2 to the nozzle 3030ab2 is stopped.

As shown in FIG. 12, at time t2, the nozzle 3030ab3 of the ink jet head 301ab is located in a region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab3 is stopped at time t2.
As shown in FIG. 13, at time t3, the nozzle 3030ab4 of the inkjet head 301ab comes to be located in a region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab4 is stopped at time t3. Further, at time t3, the nozzle 3030aa1 of the inkjet head 301aa comes to be located in the central portion (hereinafter simply referred to as “central portion”) in the movement direction (Y-axis direction) of the head portion 30 of the opening 17G. At this time, the first drive signal SG1 is applied to the nozzle 3030aa1, and ink droplets are ejected.

As shown in FIG. 14, at time t4, the nozzle 3030ab2 of the inkjet head 301ab is positioned outside the region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab2 is resumed at time t4.
As shown in FIG. 15, at time t5, the nozzle 3030ab5 of the inkjet head 301ab comes to be located in a region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab5 is stopped at time t5. Further, at time t5, the nozzle 3030aa2 of the inkjet head 301aa comes to be positioned at the center of the opening 17G. At this time, the first drive signal SG1 is applied to the nozzle 3030aa2 and ink droplets are ejected.

As shown in FIG. 16, at time t6, the nozzle 3030ab3 of the inkjet head 301ab is located outside the region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab3 is resumed at time t6.
As shown in FIG. 17, at time t7, the nozzle 3030ab6 of the ink jet head 301ab is located in a region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab6 is stopped at time t7. At time t7, the nozzle 3030aa3 of the inkjet head 301aa comes to be positioned at the center of the opening 17G. At this time, SG1 is applied to the nozzle 3030aa3 and ink droplets are ejected.

As shown in FIG. 18, at time t8, the nozzle 3030ab4 of the ink jet head 301ab is located outside the region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab4 is resumed at time t8.
As shown in FIG. 19, at time t9, the nozzle 3030aa4 of the inkjet head 301aa comes to be positioned at the center of the opening 17G. At this time, SG1 is applied to the nozzle 3030aa4 and ink droplets are ejected.

As shown in FIG. 20, at time t10, the nozzle 3030ab5 of the inkjet head 301ab is located outside the region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab5 is resumed at time t10.
As shown in FIG. 21, at time t11, the nozzle 3030aa5 of the inkjet head 301aa comes to be positioned at the center of the opening 17G. At this time, SG1 is applied to the nozzle 3030aa5 and ink droplets are ejected.

  As shown in FIG. 22, at time t12, the nozzle 3030ab6 of the inkjet head 301ab comes to be located outside the region facing the opening 17R. Therefore, the application of SG2 to the nozzle 3030ab6 is resumed at time t12. At the same time, at time t12, the nozzle 3030ab2 of the inkjet head 301ab comes to be positioned in a region facing the opening 17B, and the application of SG2 to the nozzle 3030ab2 is stopped.

  The method for controlling the drive signal applied to each nozzle of the inkjet heads 301aa and 301ab of the HG 301a has been described above. In this embodiment, the control method of the drive signal applied to each nozzle of the inkjet heads 301ba and 301bb of the HG 301b is also applied to each nozzle 3030 of the inkjet head 301bb because the head rank of the inkjet head 301ba is HR5. SG2 is the same except that Vm is Vm5.

[Summary]
In the case of the organic EL display panel, since the film thickness of the organic light emitting layer 11 is as thin as about 20 to 100 [nm], the volume variation of minute droplets appears as a difference in light emission luminance, and the influence on the display quality. Will grow. In particular, when the volume variation of ejected ink droplets between adjacent ink jet heads in the main scanning direction is large, band-like variation occurs in the light emission luminance, and display quality is impaired. Higher display quality is required as the display panel becomes higher in definition, and the volume variation of the ink droplets ejected from the inkjet head needs to be further suppressed.

  In the inkjet apparatus 1000 according to the present embodiment, two inkjet heads 301 in which nozzles 3030 are arranged in a row in the sub-scanning direction (column direction) are arranged in parallel in the main scanning direction (row direction). The inkjet head 301 is held as a set by a holder 303, and the head unit 30 in which a plurality of sets of inkjet heads 301 are arranged in the sub-scanning direction is scanned on the application target substrate. Then, among the plurality of openings 17 provided on the application target substrate while scanning the head unit 30, the color opening that matches the ink color of the inkjet head 301 (G color in the first embodiment). An ink droplet is ejected from the nozzle 3030 at a timing when the nozzle 3030 faces the portion 17 to form an organic light emitting layer.

  At that time, one inkjet head 301 (first nozzle group) (in the first embodiment, the inkjet head 301aa) of one set of inkjet heads 301 (in the first embodiment, the head group HG301a is a representative example). ) Nozzle 3030 is opposed to the target opening (opening for color matching the ink color) 17, that is, the timing at which droplets should be ejected (hereinafter referred to as “first timing”). A first drive signal SG1 is applied to the piezo element 3010 of the nozzle 3030 to eject ink droplets.

  The timing at which the nozzle 3030 of one ink jet head 301 faces the opening 17 for different ink colors (R color and B color in the first embodiment) is the timing at which droplet discharge should be prohibited (hereinafter, referred to as “the droplet discharge”). The second drive signal SG2 is not applied to the piezo element 3010. The reason why the first drive signal SG1 is not applied is that, when a droplet is ejected to an opening for a color different from the ink color, color mixing is caused and display quality is impaired. Even if the diaphragm 301h is deformed by the piezo element 3010 when the second drive signal SG2 is applied, the deformation is deformation that does not cause droplets to be ejected. There is a possibility that a phenomenon in which ink droplets are dropped or ink droplets are scattered may occur. Therefore, the second drive signal SG2 is not applied at the second timing.

  In the first embodiment, at the third timing that is neither the first timing nor the second timing, that is, at the timing at which the liquid droplets may or may not be ejected, The first drive signal SG1 and the second drive signal SG2 are not applied to the nozzle 3030. The third timing is a timing facing the partition wall layer 7 that partitions the adjacent openings 17 and the contact hole 5 (recessed portion 8) provided in the partition wall layer 7.

  Here, with respect to the other inkjet head 301 (second nozzle group) (the inkjet head 301ab in the first embodiment), the second timing is the timing at which the nozzle 3030 faces the opening for different colors. The first drive signal SG1 and the second drive signal SG2 are not applied. This is for the same reason as described above, and is to prevent unnecessary ink ejection that causes color mixing. The second drive signal SG2 is applied at the first timing and the third timing. If the timing is opposite to the color opening 17 that matches the ink color and the timing facing the partition layer 7 and the contact hole 5 (recessed portion 8), the second drive signal SG2 is applied and the timing is not reached. This is because even if necessary ink droplets are ejected, the problem of color mixing does not occur.

In the inkjet head 301 (second nozzle group) (the inkjet head 301ab in the first embodiment), when the nozzle 3030 is at the second timing, the second drive is performed with respect to the piezoelectric element 3010 of the nozzle 3030. The signal SG2 may be applied.
In this way, the second drive signal SG2 is applied to the piezo element 3010 of the nozzle 3030 of the other inkjet head 301 to generate heat, and the generated heat is transmitted to the one inkjet head 301 through the holder 303, By increasing the ink temperature of the inkjet head 301 to reduce the ink viscosity, it is possible to improve the ease of ink ejection of one inkjet head 301 (make it easier to eject ink).

  At this time, by changing the magnitude of the peak voltage of the second drive signal SG2 in accordance with the degree of ease of ejection of the inkjet head 301, the degree to which the ease of ejection is improved can be controlled. That is, for the nozzle 3030 of the inkjet head 301 in the same set as the inkjet head 301 with lower ejection easiness, the magnitude of the peak voltage Vm of the second drive signal SG2 to be applied is made larger and more heat is generated. , And by increasing the temperature of the ink and lowering the viscosity, the ease of ejection can be greatly improved.

As a result, the ease of ink ejection between adjacent head groups is made uniform, and band-like variations in the ink ejection amount are suppressed, and as a result, the occurrence of band-like variations in the light emission luminance of the organic EL display panel is prevented. Can do.
Further, when the nozzle 3030 to which the first drive signal SG1 is applied and the nozzle 3030 to which the second drive signal SG2 are applied are mixed in the same nozzle row, signal crosstalk occurs and accurate ejection is performed. There is a possibility that the problem that control becomes impossible occurs. Further, the vibration of the vibration plate 301h deformed by the piezo element 3010 when a drive signal is applied is conducted to the adjacent nozzle, causing an error in the volume of the ejected liquid droplet, or unnecessary liquid droplet ejection. There is a possibility that the problem of increasing the number of splashes and splashes may occur. By separating the nozzle row to which the first drive signal SG1 is applied and the nozzle row to which the second drive signal SG2 is applied, occurrence of the above problem can be suppressed.

<< Embodiment 2 >>
In the first embodiment, two inkjet heads 301 each having one nozzle row are held as a set by a holder 303, and the first drive signal SG1 is supplied to the nozzle 3030 of one inkjet head 301 of the set of inkjet heads 301. The configuration has been described in which the second drive signal is applied to the nozzle 3030 of the other inkjet head 301 to generate heat even when the ink droplets are ejected by applying.

In the second embodiment, a case where one inkjet head has two nozzle rows will be described.
FIG. 25 is a diagram illustrating a main configuration of the inkjet apparatus 2000 according to the second embodiment. The inkjet apparatus 2000 is different from the inkjet apparatus 1000 according to Embodiment 1 in that an inkjet head 2301 is provided in the head unit 2030 instead of the pair of inkjet heads 301 held by the holder 303. The basic configuration is the same as that of the ink jet apparatus 1000.

As for the functional block diagram of the inkjet device 2000, the head unit 30 is the head unit 2030 in the functional block diagram of the inkjet device 1000 shown in FIG. 6, and the configuration of the head unit 2030 is the same as the configuration of the head unit 30. Here, illustration is omitted.
FIG. 26 is a partially cutaway perspective view showing a schematic configuration of the inkjet head 2301.

FIG. 27 is a diagram showing a positional relationship between the application target substrate and the head portion 2030 in the manufacturing process of the organic EL display panel.
As shown in FIG. 26, the inkjet head 2301 is provided with partition walls 301d, cavities 301e, nozzle holes 3031, and piezo elements 3010 on both sides of a flow path 301g, and has two nozzle rows of a row and b row. Provided (see FIG. 27). The nozzle rows of the a row and the b row share one reservoir (flow path 301g).

  In the second embodiment, the nozzle rows of the a and b rows play the same role as the nozzle row of the inkjet head 301aa and the nozzle row of 301ab in the first embodiment, respectively, and the same drive signals are applied. That is, the first drive signal SG1 is applied to the piezo elements 3010 of the nozzles 3030 (first nozzle group) in the a row at the first timing to eject ink droplets, and the second and third At this time, neither the first drive signal SG1 nor the second drive signal SG2 is applied. For the piezoelectric elements of the nozzles 3030 (second nozzle group) in the b row, neither the first drive signal nor the second drive signal is applied at the second timing, and at the first timing and the third timing. In some cases, the second drive signal SG2 is applied.

  Even in the configuration of the second embodiment, the second drive signal SG2 is applied to the piezo elements 3010 of the nozzles 3030 in the b row to generate heat, and the generated heat is stored in the reservoir via the partition wall 301d, the nozzle plate 301i, the diaphragm 301h, and the like. Since the ink viscosity is lowered by increasing the temperature of the ink by conducting to the ink stored in the nozzle, it is possible to improve the discharge easiness of the nozzles 3030 in the b row sharing the reservoir.

  In this way, the second drive signal SG2 is applied to the piezo elements 3010 of the nozzles 3030 in the b row of the inkjet head 2301 to generate heat, and the generated heat is transmitted to the ink stored in the reservoir, thereby increasing the ink temperature. Thus, by reducing the ink viscosity, it is possible to improve the ink discharge easiness of the nozzles 3030 in the row a (make it easier to eject ink).

  At this time, by changing the magnitude of the peak voltage of the second drive signal SG2 in accordance with the degree of easy ejection of the inkjet head 2301 (easiness of ejection of the nozzles 3030 in the row a), the degree of improving the ease of ejection is improved. Can be controlled. That is, for the nozzles 3030 in the b row of the inkjet head 2301 having a lower ejection ease, the magnitude of the peak voltage Vm of the second drive signal SG2 to be applied is increased to generate more heat, By increasing the temperature of the ink to lower the viscosity, it is possible to greatly improve the ease of ejection.

As a result, even with the configuration of the second embodiment, the ease of ink ejection between the adjacent inkjet heads 2301 is made uniform, and band-like variations in the ink ejection amount are suppressed. As a result, the light emission luminance of the organic EL display panel is increased. The occurrence of band-like variations can be prevented.
[Modification]
Although the first and second embodiments have been described above, the present invention is not limited to these embodiments. For example, the following modifications can be considered.

  (1) In each of the above embodiments, the configuration in which the degree of heat generation is adjusted by changing the magnitude of the peak voltage of the second drive signal SG2 in accordance with the ease of ejection of the inkjet head has been described. It is not a thing. For example, the degree of heat generation may be adjusted by changing the frequency of the second drive signal SG2 having a constant peak voltage. Here, a case where the adjustment method of the present modification is applied to the ink jet apparatus 1000 of Embodiment 1 will be described as an example.

  FIG. 28 is a timing chart showing drive signals applied to the nozzles of the inkjet heads 301ba and 301bb of the HG 301b in the first modification. The timing chart showing the drive signals applied to the nozzles of the inkjet heads 301aa and 301ab of the HG 301a is the same as the timing chart of the first embodiment shown in FIG.

  Since the head rank of the HG 301a is HR1 (high discharge ease) and the head rank of the HG 301b is HR5 (low discharge ease), in the first embodiment, the first rank applied to the nozzle 3030 of the inkjet head 301ab of the HG 301a. The magnitude of the peak voltage of the second drive signal SG2 is Vm1, and the magnitude of the peak voltage of the second drive signal SG2 applied to the nozzle 3030 of the inkjet head 301bb of the HG 301b is Vm5.

  In the present modification, as shown in FIG. 28, the peak voltage of the second drive signal SG2 applied to the nozzle 3030 of the inkjet head 301bb of the HG 301b is Vm1, but its frequency is high. Since the number of pulses applied per unit time increases as the frequency increases, more heat is generated in the piezo element 3010 as the frequency increases even when the magnitude of the peak voltage is the same. Therefore, the degree of heat generation can be adjusted by increasing the frequency of the second drive signal SG2 for an inkjet head with low ejection easiness.

  (2) The degree of heat generation can also be adjusted by changing the number of piezo elements 3010 of the nozzle 3030 to which the second drive signal SG2 is applied. In the modified example 2, as shown in FIG. 29, in the nozzle 3030 of the inkjet head 301ab of the HR1 HG 301a, the second drive signal SG2 is applied only to the nozzles 3030ab1 and 3030ab6, and the remaining nozzles 3030ab2 to 3030ab5 are applied. Does not apply the second drive signal SG2. Note that a timing chart showing drive signals applied to the nozzles of the inkjet heads 301ba and 301bb of the HG 301b is the same as the timing chart of the first embodiment shown in FIG. At this time, the head rank of the HG 301a is HR1, but the magnitude of the peak voltage of the second drive signal SG2 applied to the nozzle 3030 of the inkjet head 301ab is Vm5.

Here, for example, for the HR2 inkjet head, the second drive signal SG2 is applied to the three nozzles 3030, the four nozzles for HR3, and the five nozzles for HR4. The degree of heat generation can be adjusted by adjusting the number of nozzles 3030 to which the signal SG2 is applied according to the head rank (ease of ejection).
At this time, since heat is released into the atmosphere toward the outside of the inkjet head and the temperature is likely to drop, the nozzle 3030 located outside is preferentially selected and the second drive signal SG2 is applied. Also good.

(3) In the first embodiment, the inkjet head 301 is arranged in a posture in which the row of the nozzles 3030 is inclined at a predetermined angle with respect to the main scanning direction. However, the present invention is not limited to this. For example, as shown in FIG. 30, the inkjet head 301 may be arranged in a posture in which a plurality of nozzles 3030 are arranged in a direction orthogonal to the main scanning direction.
(4) In the second embodiment, the inkjet head 2301 is arranged in a posture in which the row of nozzles 3030 is inclined at a predetermined angle with respect to the main scanning direction. For example, as shown in FIG. 31, the inkjet head 2301 may be arranged in a posture in which a plurality of nozzles 3030 are arranged in a direction orthogonal to the main scanning direction.

  (5) In the second embodiment, the inkjet head 2301 has two nozzle rows in which a plurality of nozzles 3030 are arranged at substantially equal intervals. However, the present invention is not limited to this. For example, as shown in FIG. 32, two nozzle arrays may be arranged in series, and another two nozzle arrays may be arranged in series, and the inkjet head 3301 may be arranged in parallel. .

(6) Moreover, as shown in FIG. 33, the inkjet head 3301 may be arrange | positioned with the attitude | position in which a nozzle row orthogonally crosses with respect to the main scanning direction.
(7) Furthermore, the number of nozzle rows arranged in parallel in the main scanning direction is not limited to two, and may be three or more.
(8) In each of the above embodiments and modifications, for the piezoelectric element 3010 of the nozzle 3030 of the second nozzle group (the inkjet head 301ab in the first embodiment and the b row in the second embodiment) Although the configuration in which only the second drive signal SG2 is applied has been described, the present invention is not limited to this. For example, when it is desired to increase the number of droplets ejected into the opening 17 in one scan in order to improve the coating efficiency, the first drive is applied to some or all of the nozzles 3030 of the second nozzle group as necessary. The droplet may be ejected by applying the signal SG1.

  (9) In each of the above-described embodiments and modifications, the first timing at which droplets should be ejected is the timing at which the color opening 17 that matches the ink color and the nozzle 3030 face each other. Not limited to this. The timing at which the nozzle 3030 faces the contact hole 5 (recessed portion 8) may be included in the first timing. The effect of preventing clogging of the nozzle can be expected by discharging the ink droplets for the organic light emitting layer not only to the opening 17 but also to the depression 8.

  In addition, the following effects can be expected. Since the peripheral portion of the opening 17 has a lower solvent concentration than the central portion, the evaporation rate of the solvent becomes nonuniform, and as a result, the thickness of the formed organic light emitting layer may be nonuniform. Therefore, by applying ink to both the opening 17 and the contact hole 5 (recess 8), the vapor concentration of the solvent in the region near the contact hole 5 of the opening 17 is increased, and the opening 17 The vapor concentration is made uniform over the entire area. Thereby, the effect that the organic light emitting layer of a uniform film thickness is obtained can be expected.

(10) Although not shown in FIG. 1, color filters corresponding to the respective colors are arranged above the counter electrode 14 in accordance with the positions of the respective organic light emitting layers 11. The color filter is a transparent layer provided to transmit visible light having a wavelength corresponding to R, G, and B.
Specifically, the color filter is a step of applying an ink containing a color filter material and a solvent to a substrate for forming a color filter provided with a partition layer in which a plurality of openings are formed in a matrix in pixel units. It is formed by. The present invention can also be applied to a coating process when forming this color filter.

As a color filter material, for example, a color resist manufactured by JSR Corporation can be used.
(11) The shape of the opening 17 being “long” means that the opening has a long side and a short side, and is not necessarily rectangular. For example, the shape may be a square, a circle, an ellipse, or the like.

(12) FIG. 1 shows a configuration in which each layer of the TFT layer 2 to the counter electrode 14 is laminated on the substrate 1. In the present invention, any one of the layers may be omitted, or another layer such as a transparent conductive layer may be further included.
(13) In the present invention, the depression formed following the contact hole is not an essential constituent element. For example, a portion corresponding to the depression on the partition wall layer is made of the same material as the material constituting the partition wall layer. The structure filled with may be sufficient.

Moreover, in said embodiment, although the hollow formed naturally when providing a partition layer was utilized as a hollow part, this invention is not limited to this. It is good also as forming a hollow part separately by adjusting the shape of a partition layer.
(14) In the above embodiment, the linear motor units 204 and 205 and the servo motor unit 221 are merely examples of moving means for the gantry unit 210 and the moving body 220, respectively, and their use is not essential. For example, at least one of the gantry unit and the moving body may be moved by using a timing belt mechanism or a ball screw mechanism.

(15) In the above embodiment, the number of droplets ejected from each nozzle per scan is set to one, but this number is not particularly limited. As the number of droplets ejected per scan is increased, higher landing accuracy is required, but the time required for the coating process can be shortened.
(16) In the above embodiment, the method of scanning the head portion side with respect to the application target substrate has been described, but the present invention is not limited to this. The application target substrate side may be moved with respect to the head portion in which a plurality of nozzles are arranged.

(17) In the method for manufacturing an organic EL display panel described above, it is not necessary to prepare one inkjet head each time one coating target substrate is prepared. For example, one inkjet head may be prepared every time a plurality of application target substrates are prepared, such as every ten substrates.
(18) In the present invention, the length of the head portion is not particularly limited, but the time required for the coating process can be shortened by using the head portion as long as possible.

  The method for producing the organic EL display panel of the present invention includes, for example, a method for producing an organic EL display panel used as a display for home or public facilities, or various display devices for business use, a television device, or a portable electronic device. Etc. can be suitably used.

DESCRIPTION OF SYMBOLS 1 Substrate 2 TFT layer 3 Feeding electrode 4 Interlayer insulating film 5 Contact hole 6 Pixel electrode 7 Partition layer 8 Depression 9 Hole injection layer 10 Hole transport layer 11 Organic light emitting layer 12 Electron transport layer 13 Electron injection layer 14 Counter electrode 17 Opening 20 Inkjet table 30, 2030 Head unit 100 Organic EL display panel 200 Base 201A, 201B, 202A, 202B Stand 203A, 203B Guide shaft 204, 205 Linear motor unit 210 Gantry unit 220 Moving body 300 Discharge control unit 301, 2301 , 3301 Inkjet head 301c Cavity plate 301d Partition wall 301e Cavity 301f Channel 301g Channel (reservoir)
302 Main Body 303 Holder 1000, 2000 Inkjet Device 3010 Piezo Element 3030 Nozzle 3031 Nozzle Hole

Claims (20)

A first nozzle group in which a plurality of nozzles each having a nozzle hole and a piezoelectric element for discharging a liquid material as droplets from the nozzle hole are arranged in a line; and the nozzles of the first nozzle group; A plurality of other nozzles having the same configuration are arranged in a row, a second nozzle group arranged in parallel adjacent to the first nozzle group, and a drive signal for driving the piezoelectric element. An ink jet device having a discharge control unit for
The piezoelectric element ejects droplets when a first drive signal is applied, but does not eject droplets when a second drive signal is applied,
The discharge controller is
For each of the piezoelectric elements of the nozzles of the first nozzle group,
When it is the first timing at which the droplet should be ejected, the first drive signal is applied, and the second timing at which the ejection of the droplet should be prohibited and the second timing at the first timing. When it is the third timing that is not the timing of the above, neither the first drive signal nor the second drive signal is applied,
For each piezoelectric element of at least some of the nozzles of the second nozzle group,
An ink jet apparatus that applies the second drive signal. The second drive signal is applied to each of the piezoelectric elements of at least some of the nozzles of the second nozzle group at the first timing or the third timing. The inkjet apparatus according to 1. The inkjet apparatus according to claim 1, wherein the ejection control unit increases the peak voltage of the second drive signal as the ease of ink ejection of the first nozzle group is lower. The inkjet apparatus according to claim 1, wherein the ejection control unit increases the frequency of the second drive signal as the ease of ink ejection of the first nozzle group is lower. The ejection control unit may reduce the second drive signal with respect to the piezoelectric elements of more nozzles among the plurality of nozzles constituting the second nozzle group as the ink ejection ease of the first nozzle group is lower. The inkjet device according to claim 1, wherein the inkjet device is applied. The inkjet apparatus according to claim 1, wherein the first nozzle group and the second nozzle group are disposed in separate inkjet heads adjacent to each other. The inkjet apparatus according to claim 1, wherein the first nozzle group and the second nozzle group are disposed in one inkjet head. The inkjet apparatus according to claim 1, wherein the liquid is an ink containing an organic material and a solvent. The ejection control unit is configured to apply the first drive signal to the piezoelectric elements of one or more nozzles of the second nozzle group other than the at least some of the nozzles when the first timing is reached. The inkjet device according to claim 1, wherein the inkjet device is applied. The organic material is a material used for forming an organic light emitting layer of an organic EL display panel,
The first timing is a timing at which the nozzle faces a color application region corresponding to the organic material,
The inkjet apparatus according to claim 8, wherein the second timing is a timing at which the nozzle faces a coating area of a color that does not correspond to the organic material. An EL substrate provided with a partition layer in which a plurality of openings are formed in a matrix for each pixel;
A first nozzle group in which a plurality of nozzles each having a nozzle hole and a piezoelectric element for ejecting ink droplets containing an organic material and a solvent from the nozzle hole are arranged in a row; A plurality of different nozzles having the same configuration as the nozzles of one nozzle group, and a second nozzle group arranged in parallel adjacent to the first nozzle group;
An ejection control unit that provides the piezoelectric element with a drive signal for driving the piezoelectric element;
A first step of preparing
A second step of ejecting the liquid droplets from the nozzles corresponding to the openings to the openings while scanning the head portion in the row direction with respect to the EL substrate,
In the second step, the discharge controller is
For each of the piezoelectric elements of the nozzles of the first nozzle group,
When it is the first timing at which the droplet should be ejected, the first drive signal is applied, and the second timing at which the ejection of the droplet should be prohibited and the second timing at the first timing. When it is the third timing that is not the timing of the above, neither the first drive signal nor the second drive signal is applied,
For each piezoelectric element of at least some of the nozzles of the second nozzle group,
The method for manufacturing an organic EL display panel, wherein the second drive signal is applied. The second drive signal is applied to each of the piezoelectric elements of at least some of the nozzles of the second nozzle group at the first timing or the third timing. 11. A method for producing an organic EL display panel according to 11. In the second step,
The method of manufacturing an organic EL display panel according to claim 11, wherein the ejection control unit increases the peak voltage of the second drive signal as the ink ejection ease of the first nozzle group is lower. In the second step,
The method of manufacturing an organic EL display panel according to claim 11, wherein the ejection control unit increases the frequency of the second drive signal as the ease of ink ejection of the first nozzle group is lower. In the second step,
The ejection control unit may reduce the second drive signal with respect to the piezoelectric elements of more nozzles among the plurality of nozzles constituting the second nozzle group as the ink ejection ease of the first nozzle group is lower. The method for producing an organic EL display panel according to claim 11, wherein: is applied. In the first step,
The method for manufacturing an organic EL display panel according to claim 11, wherein the first nozzle group and the second nozzle group are disposed in separate adjacent ink jet heads. In the first step,
The method of manufacturing an organic EL display panel according to claim 11, wherein the first nozzle group and the second nozzle group are arranged in one inkjet head. The said organic material is a material used in order to form an organic light emitting layer. The manufacturing method of the organic electroluminescence display panel of Claim 11 characterized by the above-mentioned. In the second step,
The ejection control unit is configured to apply the first drive signal to the piezoelectric elements of one or more nozzles of the second nozzle group other than the at least some of the nozzles when the first timing is reached. The method for producing an organic EL display panel according to claim 11, wherein: is applied. The organic material is a material used to form an organic light emitting layer,
The first timing is a timing at which the nozzle faces the opening of a color corresponding to the organic material,
The method of manufacturing an organic EL display panel according to claim 11, wherein the second timing is a timing at which the nozzle faces the opening of a color that does not correspond to the organic material.

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