JP2003121630A - Electro-optical device and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent poor quality due to uneven film thickness between pixels. SOLUTION: A plurality of pixel portions 13 are formed by a discharged color material.
Is provided. The thickness of the color material in each pixel portion 13 is within ± 1.4% of the average thickness of all the pixel portions.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a color filter,
The present invention relates to an electro-optical device such as an electroluminescence element matrix, and more particularly to an electro-optical device having a substrate manufactured by ejecting ink droplets at positions where pixels are formed, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a method of manufacturing an electro-optical device component such as a color filter, a method applying an ink jet method has been proposed. In this method, partitions are formed in a matrix pattern on a transparent substrate in a pattern corresponding to pixel portions, and then a coloring liquid containing R, G, and B dyes (hereinafter referred to as ink droplets) is applied from an inkjet head using an inkjet method. ) Is being discharged into the partition. When the ink droplets are ejected, the ink droplets are applied to the extent that they rise above the partition on the substrate, and the volume is reduced by baking, drying and curing at a predetermined temperature to flatten the interior of the partition to form a colored layer. .

According to this method, the R, G, and B colored layers can be formed at one time, and since the amount of the coloring liquid used is not wasted, the productivity is greatly improved and the cost is reduced. The effect of can be obtained.

[0004]

However, the conventional electro-optical device and the method for manufacturing the same as described above have the following problems.
There are the following problems. A plurality of pixel units for each color are arranged in a predetermined pattern, but the size of the region where the pixel units are arranged on the substrate is wider than the size of the inkjet head. Therefore, normally, after the substrate and the inkjet head are relatively moved in a predetermined direction (scanning direction) to eject ink droplets, the inkjet head is stepwise moved in a direction orthogonal to the scanning direction to start a line feed, and then again. The operation of ejecting ink droplets by repeatedly moving the substrate and the inkjet head in the scanning direction is repeated.

However, since there is a time lag in the ejection of ink droplets before and after line feed and the ink drying state is different, color unevenness called line feed unevenness occurs between the pixels at the line feed portion, and density is increased. This causes unevenness, resulting in poor quality for a liquid crystal display device, for example. In particular, when pixels with uneven film thickness are lined up at the line feed portion, line feeding unevenness is more visible than when pixels with uneven film thickness are dispersed, and there is a high possibility that the quality will be poor. was there.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide an electro-optical device capable of preventing quality defects due to film thickness unevenness between pixels and a manufacturing method thereof. To do.

[0007]

In order to achieve the above object, the present invention employs the following constitutions. An electro-optical device of the present invention is an electro-optical device including a substrate in which a plurality of pixel portions are formed of ejected color material, and the film thickness of the color material in each pixel portion is an average film thickness of all pixel portions. Against ±
It is characterized by being within 1.4%.

Usually, when the pixel portions having the film thickness unevenness are dispersed, the color difference of the color tone in which the density unevenness (color unevenness) can be visually recognized is about ΔE <3, and this color difference is formed as the pixel portions on the substrate. When converted into the film thickness of the colored material, the average film thickness is within ± 5%. However, when the pixel portions having the film thickness unevenness are arranged linearly, the film thickness unevenness is visually recognized even if it is ± 5% or less. Therefore, in the present invention, it is possible to prevent the line feed unevenness from being visually recognized by setting the film thickness unevenness within ± 1.4% of the average film thickness.

This film thickness unevenness is ± 1.2 with respect to the average film thickness.
It is more preferably within 5%. Accordingly, in the present invention, it is possible to more reliably prevent the line feed unevenness from being visually recognized.

A method of manufacturing an electro-optical device according to the present invention is a method of manufacturing an electro-optical device in which a plurality of pixel portions are formed by a color material ejected on a substrate, and the film thickness of the color material in each pixel portion. Is formed within ± 1.4% of the average film thickness of all pixel portions.

When the pixel portions having the film thickness unevenness are arranged in a straight line, the film thickness unevenness is visually recognized even if it is ± 5% or less. Therefore, in the present invention, the line feed unevenness can be prevented from being visually recognized by setting the film thickness unevenness within ± 1.4% of the average film thickness.

This film thickness unevenness is ± 1.2 with respect to the average film thickness.
It is more preferably within 5%. As a result, in the present invention, it was possible to more reliably prevent the line feed unevenness from being visually recognized.

Further, in the present invention, when the set thickness of the color material formed in each pixel portion is within ± a% (a> 0) with respect to the average film thickness and the color material is discharged while moving the substrate. When the film thickness of the color material of each pixel portion is within ± b% (b> 0) with respect to the average film thickness generated by the substrate movement per time, a ≧
It is also possible to adopt a procedure of forming each pixel portion by n times of moving the substrate satisfying b / n (n is an integer of 1 or more).

As a result, in the present invention, the film thickness when the color material is ejected in one movement of the substrate to form the pixel portion is the target set film thickness (for example, ± 1. Even if the distribution (unevenness) is larger than 4% or less than ± 1.25%), the pixel portions in which the unevenness is formed are dispersed by ejecting the color material by moving the substrate a plurality of times. As a result, the film thickness of the color material of each pixel portion with respect to the average film thickness is averaged according to the number of times the substrate is moved. Therefore, more than the number of times satisfying a ≧ b / n,
By discharging the coloring material by moving the substrate, it is possible to suppress the film thickness unevenness to the extent that it is not visually recognized.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electro-optical device and a method of manufacturing the same according to the present invention will be described below with reference to FIGS. Here, for example, an example of manufacturing a color filter as a component of an electro-optical device will be described.

FIG. 1 is a plan view showing a planar shape of a color filter substrate used when manufacturing a color filter in this embodiment. FIG. 2 is an enlarged view of a circle indicated by reference character A in FIG.

As shown in FIG. 1, the color filter substrate (substrate) 12 is in a state in which a plurality of panel chips 11 to be one color filter are arranged on a plane. In this embodiment, one color filter substrate 12
Is composed of about 100 panel chips 11. At the time of manufacturing the color filter, the plurality of panel chips 11 are collectively subjected to ink ejection and drying processing, and then separated into panel chip units to form color filters.

As shown in FIG. 2, the panel chip 11
Includes a plurality of pixel portions 13 arranged in a matrix, and a boundary between the pixel portions is divided by a partition (black matrix) 14. At the time of manufacturing the color filter, a few drops of ink (coloring material) of any one of red, green, and blue is ejected to each of the pixel portions 13. Figure 2
In the above example, the arrangement of red, green and blue is a so-called delta type, but other arrangements such as stripe type and mosaic type may be used as long as the three colors are evenly arranged.

FIG. 3 is a sectional view taken along line BB of FIG.
The panel chip 11 that constitutes the color filter substrate includes a light transmitting layer 15 and a partition 14 that is a light shielding layer.
The part where the partition 14 is not formed (removed) is
The pixel portion 13 is formed. By ejecting liquid ink of each color onto the pixel portion 13 and drying and solidifying the liquid ink,
It becomes a color filter.

Hereinafter, the manufacturing process of the color filter according to the manufacturing method of this embodiment will be described in more detail.

For example, a film thickness of 0.7 mm, a vertical length of 38 cm,
The surface of a transparent substrate having a width of 30 cm and made of non-alkali glass is washed with a cleaning liquid containing 1% by weight of hydrogen peroxide in hot concentrated sulfuric acid, rinsed with pure water, and then air-dried to obtain a clean surface. A chromium film was formed on this surface by sputtering to have an average film thickness of 0.2 μm to obtain a metal layer. A photoresist was spin-coated on the surface of this metal layer. The substrate was dried on a hot plate at 80 ° C. for 5 minutes to form a photoresist layer.

A mask film on which a desired matrix pattern was drawn was brought into close contact with the surface of the substrate and exposed with ultraviolet rays. Next, add this to 8 parts of potassium hydroxide.
The photoresist in the unexposed portion was removed by immersing in an alkali developing solution containing it in a weight percentage, and the resist layer was patterned. Then, the exposed metal layer was removed by etching with an etching solution containing hydrochloric acid as a main component. In this way, a light shielding layer (black matrix) having a predetermined matrix pattern was obtained.

A negative type transparent acrylic photosensitive resin composition was applied on this substrate by spin coating. After prebaking at 100 ° C. for 20 minutes, UV exposure was performed using a mask film on which a predetermined matrix pattern shape was drawn. The unexposed portion of the resin was developed with an alkaline developer, rinsed with pure water, and then spin-dried. After baking as final drying at 200 ℃
For 30 minutes to sufficiently cure the resin portion to form a bank layer.

Dry etching, that is, atmospheric pressure plasma treatment was performed to improve the ink wettability of the colored layer forming region partitioned by the obtained light shielding layer and bank layer.
A high voltage is applied to a mixed gas of helium and 20% oxygen, a plasma atmosphere is formed at an etching spot under atmospheric pressure, and a substrate is etched by passing under the etching spot to form a colored layer together with a bank layer. A region (exposed surface of the glass substrate) was activated.

Ink, which is a coloring material, was ejected from the ink jet head while being controlled with high accuracy to the colored layer forming region, and the ink was applied. As the inkjet printing head, a precision head applying the piezoelectric effect is used, and minute ink droplets are formed in each colored formation region, for example, 10
Drops, selectively skipped. In order to prevent the flight speed from the head to the target colored layer formation area, flight bending, and the generation of split stray droplets called satellites, the voltage that drives the piezo element of the head as well as the physical properties of the ink and its waveform are used. is important. Therefore, a pre-set waveform was programmed to apply the ink droplets in three colors of red, green, and blue to form a colored layer having a predetermined color arrangement pattern.

Here, the ink jet head and the substrate 12
Is relatively moved in the X direction, for example, as a scanning direction, and a predetermined color ink is ejected from a nozzle to a predetermined pixel portion 13 during the relative movement (hereinafter, it is assumed that the substrate 12 moves. ). Usually, the size of the area in the Y direction in which the pixel portions 13 are arranged is wider than the size of the area in which the nozzles are arranged. Therefore, in the example of FIG. 2, ink is ejected to the pixel portion 13 in the region R1 while moving the substrate 12 in the X direction, and then the substrate 12 is step-moved in the Y direction to line-feed the pixel forming portion and then again. Ink is ejected to the pixel portions 13 in the region R2 while moving in the X direction (note that the number of pixel portions formed by one movement of the substrate is two columns here for convenience).

As an example of the ink composition, a thermosetting acrylic resin of 20% by weight, an organic pigment of 10% by weight, and a solvent such as a diethylene glycol butyl ether derivative of 70% by weight were used.

For drying after coating, the ink layer is set by leaving it in a natural atmosphere for 3 hours, and then, for example, 80
Heating on a hot plate at ℃ for 40 minutes (prebaking)
Finally, the ink layer was cured by heating (post-baking) at 200 ° C. for 30 minutes in an oven to obtain a colored layer. As a result of this drying, as shown in FIG. 4, the ink in the pixel portion 13 having the thickness T1 immediately after ejection has a thickness of T2 (pre-baking) and T3 (post-baking) because the solvent is evaporated by heating and the volume is reduced. ), And finally only the solid content of the ink remains to form a film.

Here, the ink is moved by moving the ink jet head having a plurality of nozzles and the substrate relative to each other.
Although a predetermined nozzle ejects to a specific pixel portion 13, there is a difference in film thickness (T3 in FIG. 4) between the plurality of pixel portions 13 due to a difference in ink ejection amount between nozzles. So-called film thickness unevenness may occur, and density unevenness (color unevenness) may occur due to this film thickness unevenness. This color unevenness is not visually recognized when the color difference ΔE of the color tone is less than 3 when the pixel portions 13 are viewed independently. In this case, the color difference ΔE <3 is converted into the film thickness of each pixel portion 13. This corresponds to within ± 5% of the average film thickness of all pixel portions 13 (hereinafter, the difference in film thickness from the average film thickness of all pixel portions 13 is simply referred to as film thickness unevenness).

Therefore, when the pixel portion 13 is formed in a state where the ink is ejected under the ejection conditions such as the drive voltage and the waveform described above, and the film thickness unevenness is suppressed to within ± 5%, one pixel portion alone causes color unevenness. Was not visible.

However, the pixel portion 1 in the regions R1 and R2
In No. 3, since there is a time difference in the ejection of ink droplets and the dried state of ink is different, color unevenness called line feed unevenness was visually recognized between the regions R1 and R2.

Therefore, in the present embodiment, the pixel portion 13 is not formed by moving the substrate once, but the amount of ink ejected per movement of the substrate is reduced, and each pixel portion 13 is moved by moving the substrate a plurality of times. A predetermined amount of ink is ejected. At this time, for example, when the pixel unit 13 is formed by two times of substrate movements (hereinafter, n times of substrate movements are referred to as n passes; n is an integer of 1 or more), the regions R1 → R2 → R2 → R1. Ink ejection is performed, or a region R3 of two rows of pixel units extending over the regions R1 and R2, and a region R4 of one line of pixel units outside the region R3,
R5 is set, and ink is ejected in the order of regions R4 → R3 → R5 → R2 → R1. This makes it possible to suppress the occurrence of color unevenness due to the difference in drying conditions.

At the same time, the nozzles for ejecting ink to each pixel portion 13 are made different between the first ejection and the second ejection. By doing so, it becomes possible to suppress the influence of the film thickness unevenness due to the difference in the ink ejection amount between the nozzles. As described above, since the cause of unevenness is dispersed according to the number of passes, the unevenness in film thickness that occurs when the pixel unit 13 is formed in one pass is within ± b% (b> 0), and n
When the pixel portion 13 is formed by a pass, the film thickness unevenness is b /
can be considered as n.

In the present embodiment, first, when the film thickness unevenness corresponding to the color difference ΔE <3 is within ± 5% (b =
A color filter substrate was manufactured by changing the number of passes to 5).
In this case, color unevenness is visually recognized in 3 passes (n = 3; film thickness unevenness within ± 1.67%), and color unevenness is visually recognized in 4 passes (n = 4; film thickness unevenness within ± 1.25%). There wasn't.

Further, the color filter substrate was manufactured by changing the ink ejection conditions and changing the number of passes when the film thickness unevenness in one pass is within ± 7% (b = 7). In this case, color unevenness is visually recognized in 4 passes (n = 4; film thickness unevenness within ± 1.75%), and 5 passes (n = 5; film thickness unevenness within ± 1.40%).
No uneven color was visually recognized.

Further, the color filter substrate was manufactured by changing the ink ejection conditions and changing the number of passes when the film thickness unevenness within one pass is within ± 10% (b = 10). In this case, 7
Color unevenness was visually recognized in pass (n = 7; film thickness unevenness within ± 1.43%), and color unevenness was not visually recognized in 8 passes (n = 8; film thickness unevenness within ± 1.25%).

Therefore, by setting the film thickness unevenness within ± 1.4%, it was possible to prevent the occurrence of color unevenness on the color filter substrate. In other words, if the set film thickness unevenness to be formed in each pixel unit 13 is within ± a% (a> 0), a ≧ b / n
By forming the pixel unit 13 with n passes that satisfy
It is possible to manufacture a color filter substrate in which color unevenness is not visually recognized. However, considering the film thickness unevenness corresponding to the color difference ΔE <3 within ± 5% and the throughput improvement by reducing the number of passes, the pixel unit 13 is formed by four passes and the film thickness unevenness is within ± 1.25%. It is preferable.

Then, a transparent acrylic resin paint was spin-coated on the color filter substrate thus manufactured to obtain an overcoat layer having a smooth surface. Further, an electrode layer made of ITO is formed on this upper surface in a required pattern,
It was used as a color filter. The obtained color filter passed durability tests such as a heat cycle durability test, an ultraviolet irradiation test, and a humidification test, and it was confirmed that it can be sufficiently used as an element substrate for a liquid crystal display device or the like.

As described above, in the present embodiment,
The film thickness of each pixel part is ± 1.4 with respect to the average film thickness of all pixel parts.
By setting the ratio to be within%, color unevenness is not visually recognized even if there is a line feed portion on the substrate, and it is possible to prevent the occurrence of quality defects. In particular, in the present embodiment, by setting the film thickness of each pixel portion within ± 1.25% of the average film thickness of all pixel portions, the color difference ΔE <of the color tone in which the color unevenness is not visually recognized in the pixel portion alone. When ink is ejected under the condition of 3, the pixel portion can be formed with a small number of passes, which can contribute to improvement of throughput.

Further, it is extremely difficult to control the ink drying conditions in the ink jet process for the dots in the micro area, but in the present embodiment, the number of substrate movements (the number of passes) is adjusted according to the set film thickness. It is possible to prevent color irregularity from being visually recognized with a simple procedure, and it is possible to omit installation of various control devices.

In the above embodiment, the pixel portion 13 is formed by moving the substrate a plurality of times, but it is limited to this when the ink discharge amount and the like can be controlled with high precision in one pass. is not.

In the above embodiment, the color filter is taken as an example of the component of the electro-optical device, but
Not limited to this, various electro-optical devices including a process of applying and drying a coloring material such as ink, such as an EL element matrix used in an EL (electroluminescence) display device and an MLA (microlens array), The present invention can be applied.

[0043]

As described above, according to the present invention, color unevenness is not visually recognized even if a line feed portion exists on the substrate, and it is possible to prevent the occurrence of quality defects.
The effect of contributing to improvement in throughput is obtained. Further, according to the present invention, it is possible to prevent color unevenness from being visually recognized by a simple procedure, and it is possible to omit the installation of various control devices.

[Brief description of drawings]

FIG. 1 is a plan view of a color filter substrate used when manufacturing a color filter.

FIG. 2 is an enlarged view of a circle indicated by a symbol A in FIG.

FIG. 3 is a sectional view taken along line BB in FIG.

FIG. 4 is a diagram in which the film thickness of ink ejected onto a substrate changes due to drying.

[Explanation of symbols]

12 Color filter substrate (substrate) 13 pixels

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Yamada             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F term (reference) 2H048 BA11 BA45 BA48 BA64 BB02                       BB24 BB28                 2H091 FA02Y FA35Y FB03 FB04                       FB12 FC12 LA30                 5C094 AA03 AA08 AA55 CA24 ED03                 5G435 AA01 AA04 CC12 GG12 KK05                       KK07

Claims (5)

[Claims] 1. An electro-optical device comprising a substrate on which a plurality of pixel portions are formed of discharged color material, wherein the thickness of the color material in each pixel portion is relative to the average thickness of all pixel portions. The electro-optical device is within ± 1.4%. 2. The electro-optical device according to claim 1, wherein the film thickness of the color material in each pixel portion is within ± 1.25% of the average film thickness of all pixel portions. Optical device. 3. A method of manufacturing an electro-optical device, wherein a plurality of pixel portions are formed by a color material discharged onto a substrate, wherein the thickness of the color material in each pixel portion is relative to the average thickness of all pixel portions. Forming within ± 1.4%. 4. The method for manufacturing an electro-optical device according to claim 3, wherein the film thickness of the color material in each pixel portion is formed within ± 1.25% of the average film thickness of all pixel portions. A method for manufacturing a characteristic electro-optical device. 5. The method of manufacturing an electro-optical device according to claim 3, wherein a set film thickness of the color material formed in each pixel portion is within ± a% (a> 0) with respect to the average film thickness. When the color material is ejected while moving the substrate, the thickness of the color material of each pixel portion is within ± b% (b> 0) with respect to the average film thickness generated by one movement of the substrate. Then, each pixel portion is formed by n times of substrate movement satisfying a ≧ b / n (n is an integer of 1 or more).