JP2003161825A - Color filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that display quality of a liquid crystal element is lowered because the alignment processing of a liquid crystal alignment film is not uniform, when a color filter whose flatness of colored layer is insufficient is used. <P>SOLUTION: In the color filter for the liquid crystal display element for providing the colored layer provided with three original colors by an inkjet method on a prescribed opening part of a resin-made black matrix (hereafter, referred to as BM) formed on a transparent substrate, the height of BM is HB, the height of the colored layer is HC, the difference between HB and HC is HB-HC=h(>0), furthermore, when the ink contact angle for the colored layer to a BM material is set to θI, the tangential line of the black matrix edge part at the height of (HB-h) and an intersection angle θB with a BM upper end face is in the neighborhood of θI. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter used in a liquid crystal display device.

[0002]

2. Description of the Related Art A color filter for a liquid crystal display element is a main component of a liquid crystal display element, and one pixel is further divided into three parts to form a part through which light of three primary colors of red, green and blue respectively passes. Is. It consists of special pigments that pass only red, green, and blue, respectively, of the light from the white light source, and expresses all colors by controlling the brightness of the light by opening and closing the liquid crystal shutter. Is possible.

The color filter is composed of pixels of three primary colors of red, green and blue formed on a transparent substrate and a black matrix (hereinafter abbreviated as BM) which is a light-shielding area having a constant width between each pixel. . The BM is often formed by a method of finely patterning a metal thin film or a method of patterning a resin colored with a light shielding agent. For example, when using a resin BM, a photosensitive resin containing a black pigment and a solvent for dispersing and dissolving these components is applied on a transparent substrate by spin coating or the like, and then mask exposure and development are performed. It is formed by a so-called photolithography method in which a post bake process is performed. As a method for forming the colored layer, there are a pigment dispersion method and an inkjet method. The pigment dispersion method is as follows:
This is a method in which a photosensitive resin containing a pigment of each color and a solvent for dispersing and dissolving these components is applied over the entire surface by spin coating or the like, and then a pattern is formed by a photolithography method. The pigment dispersion method has drawbacks that the photolithography method is very complicated and the amount of material used during spin coating is very large.

Therefore, an ink jet method has been proposed which solves these drawbacks, does not require complicated mask exposure and development steps, and has an excellent advantage that cost can be reduced. The inkjet method is a method of forming a colored layer by spraying and depositing the colored layer ink on the BM opening with an inkjet head, and easily and accurately applying the desired color ink to a desired position. It has the advantage of being able to.

[0005]

However, when the colored layer is formed in the opening of the resin BM by the ink jet method, the following problems occur. That is, sufficient coloring layer flatness cannot be ensured due to the occurrence of swelling of the coloring layer at the peripheral portion of the coloring layer, which is the overlapping portion with the BM, or the entire coloring layer being convex or concave. If there is a bulge at the peripheral edge of the colored layer, the step is hardly reduced even if a transparent conductive film or a liquid crystal alignment film is formed on the color filter, and the alignment process due to rubbing of the liquid crystal alignment film becomes uneven, or the cell gap Variation occurs, and the display quality of the liquid crystal display element deteriorates. Further, if there is unevenness in the thickness of one pixel of the colored layer, this causes the unevenness of brightness within the pixel.

On the other hand, for example, Japanese Patent Laid-Open No. 08-3046
Japanese Patent Laid-Open No. 19 discloses a method of providing a flattening layer on a substrate on which BM and a colored layer have been formed. It remains unimproved, and therefore it is not possible to solve the uneven brightness in the pixel. Also, providing a flattening layer increases the number of manufacturing steps,
Manufacturing costs are disadvantageous.

[0007]

In order to solve the above-mentioned conventional problems, the color filter of the present invention is configured such that the height of the black matrix is HB, the height of the colored layer is HC, the HB and the HC are the same. BM at the height of (HB-h), where HB-HC = h (> 0) and the contact angle of the colored layer ink with the BM material is θI.
The intersection angle θB between the edge tangent line and the upper end surface of the BM is in the vicinity of θI.

Further, the height of the colored layer is lower than that of the upper end surface of the BM, and the height difference h is 0.4 μm or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A color filter according to claim 1 of the present invention is a color filter having a coloring layer in which a predetermined opening portion of a black matrix provided for light shielding is filled with a coloring layer ink, The height of the black matrix is HB, the height of the colored layer is HC, and the difference between the HB and the HC is HB-HC = h (> 0),
When the contact angle of the colored layer ink with respect to the black matrix is θI, and the angle θB between the tangent line at the height (HB-h) on the cross section of the black matrix and the upper surface of the black matrix is θB, the angle is The color filter is characterized in that θB and θI are equal to each other, and it is possible to obtain an effect that a colored layer having a high flatness can be obtained up to the peripheral portion.

A color filter according to a second aspect of the present invention is characterized in that the height of the colored layer is lower than that of the upper end surface of the black matrix, and the height difference h is 0.4 μm or less. The color filter according to item 1, wherein B is used when a liquid crystal display device is manufactured using the color filter.
It is possible to obtain an effect that it is possible to display a high-quality image by preventing nonuniformity of liquid crystal alignment and unevenness in brightness due to a difference in level between M and the coloring layer.

The color filter according to claim 3 of the present invention is the color filter according to claim 1 or 2, wherein the cross-sectional shape of the black matrix is an arc shape. BM
The effect of facilitating the formation is obtained.

In the color filter according to claim 4 of the present invention, the ink for the colored layer is a non-aqueous ink containing a pigment or dye, a photosensitive resin, and an organic solvent for dispersing and dissolving them. The color filter according to any one of claims 1 to 3, wherein Since the non-aqueous ink can produce an ink having a higher solid content ratio than the water-based ink, it is possible to suppress the volume fluctuation before and after the drying step. Therefore, when the colored layer ink is sprayed on the BM opening, the amount of the ink rising above the BM upper end surface can be suppressed to be small. Therefore, the additive for BM added to prevent the overflow of ink and B
The advantageous effect that a wide range of M materials can be selected can be obtained. Further, the thickness of the colored layer after drying and curing can be formed with high accuracy.

As the transparent substrate used in the present invention, for example, glass is often used. Also, if necessary, a transparent substrate and BM
And in order to improve the adhesiveness with the coloring layer ink,
A thin film for improving adhesion may be formed on the transparent substrate in advance. For example, ashing of the substrate surface may or may not be performed.

The material for forming the BM used in the present invention is a resin component and a black pigment and / or R (red), G
(Green), B (blue), Y (yellow), V (violet) and other mixed color black pigments,
It is a photosensitive resin containing a solvent for dispersing and dissolving these components. To form a BM on a transparent substrate using a photosensitive resin, for example, spin coating or the like may be used to form 1 to 3 μm.
It can be formed by forming a thin film having a certain thickness on the entire surface, and then exposing and developing. The resin material may be a negative type or a positive type as long as it is a photosensitive resin such as an acrylic resin used for general black photosensitive resin. As the black pigment component, carbon black or a mixed color black pigment obtained by mixing pigments such as R (red), G (green), B (blue), Y (yellow) and V (violet) is used. You can

The color layer ink used in the present invention is a non-aqueous ink comprising a pigment, a dye and the like, an appropriate resin and other additives, and an organic solvent for dispersing and dissolving them. The ink application method is an inkjet printing method in which an inkjet head is used to spray and deposit the ink on the opening of the BM, and then the ink is dried and cured.

Although a piezoelectric type ink jet head is used as the ink jet head of the present invention, the ink jet ejection method is not particularly limited. Here, the piezoelectric type ink jet head changes the volume of a desired pressure chamber by deforming a desired piezoelectric element in response to an electric drive signal, and transfers the ink filled in the pressure chamber to the front end opening of the pressure chamber. It is an inkjet head that ejects ink by sending the ink.

The colored layer ink of the embodiment of the present invention comprises a pigment, a dye and the like and a suitable resin, for example, a photosensitive resin such as an acrylic resin, and other additives.
A non-aqueous ink containing an organic solvent for dissolving was used, but it is not particularly limited.

(Embodiment 1) Embodiments of the invention described in claims 1 to 4 of the present invention will be described below.
This will be described with reference to FIGS. 1 and 2. FIG. 2 is a cross-sectional view schematically showing the manufacturing process of the color filter of the present invention.

In FIG. 2A, reference numeral 1 is a glass transparent substrate. Reference numeral 2 is a BM resin applied to the entire surface of the transparent substrate. The BM is made of a photosensitive resin in which an acrylic resin, carbon black, an organic pigment, a liquid repellent, and other additives are dispersed / dissolved in a mixed solvent of 3-methoxybutyl acetate and cyclohexanone. The photosensitive resin was applied onto the transparent substrate 1 by spin coating (700 rpm × 5 seconds) and prebaked (hot plate, 90 ° C. × 2 minutes).

Next, a predetermined pattern mask is vacuum-adhered,
Exposure (integrated illuminance: 60 mJ / cm2), development for 50 seconds (developer: 0.15% sodium carbonate aqueous solution), and rinse with pure water were performed. Further, by post-baking at 230 ° C. for 25 minutes using a horizontal laminar flow hot air circulation type drying furnace, the line width is about 22 μm, the film thickness is about 2.5 μm, and the edge portion is R. A BM having a shape of an opening of about 100 μm × about 140 μm was formed. An enlarged cross-sectional view schematically showing the BM edge portion at this time is shown in FIG.

Here, the contact angle θI in this specification is
It is a contact angle with respect to the BM of the coloring layer ink after solvent drying, in the case of the coloring layer ink used in the examples of the present invention,
The red ink was 23 °, the green ink was 22 °, and the blue ink was 23 °.

The BM edge portion obtained by the above process is
After observing with a scanning electron microscope (SEM) and taking a photograph, the crossing angle θB (reference numeral 5) between the upper end surface of the BM and the tangent to the BM edge R portion was measured with a protractor and a metal straight scale. However, the point P (reference numeral 6) where θB is in the vicinity of θI was a position 0.4 μm downward from the upper end surface of the BM.

Then, as shown in FIG. 2C, the BM is
A predetermined amount of the coloring layer ink 9 was sprayed onto the predetermined opening of the ink jet head 8. The predetermined amount is the amount by which the thickness of the colored layer after drying and curing becomes the same height as the point P, and after the present step before drying, as shown in FIG. The central portion of the ink in the portion rises in a convex shape and is higher than the upper end surface of the BM. The solid content ratio of the color layer ink used in the example of the present invention was about 50% by weight for all of the red, green, and blue inks. When measured, it was about 5.0 μm. If the amount of ink sprayed is too large or too small, the colored layer cannot have a predetermined thickness. The amount of spray was optimized by controlling the electrical signal conditions to the inkjet head and the number of ink drops when spraying ink.

Next, the organic solvent in the ink is dried and evaporated by drying on a hot plate under the conditions of 60 ° C. for 20 minutes. The evaporation of the solvent at this time reduced the volume of the colored layer, and it was possible to form a colored layer that was in contact with the BM at the point P and was horizontal to the peripheral portion.

Subsequently, the photosensitive resin in the color layer ink is cured by UV exposure under the condition of an integrated irradiation amount of 300 mJ / cm ² . No particular change in the horizontal height of the colored layer was observed before and after the curing step. Through the above process, a color filter having a colored layer 11 that is horizontal up to the peripheral edge could be obtained (FIG. 2E).

Next, as a comparative example, a BM in which the above-mentioned θB at a point 0.4 μm downward from the upper end surface of the BM is larger than the above-mentioned θI and a BM which is larger than the above-mentioned θI are prepared.
A colored layer was formed in the M opening by an inkjet method.
The amount of ink sprayed for the colored layer was the same as in the first embodiment. The shape of the edge portion of the colored layer under each condition will be described with reference to FIG. 3 schematically showing. FIG. 3A is a schematic diagram in the case of the first embodiment of the present invention, in the case where the θB at a point 0.4 μm downward from the upper end surface of the BM is near θI.
A colored layer that is horizontal to the peripheral portion is formed. Figure 3 (b)
Is the case where θB is smaller than θI. The colored layer edge portion is in contact with the BM at a position lower than the horizontal surface of the colored layer. Figure 3
(C) is the case where θB is larger than θI. The colored layer edge portion is in contact with the BM at a position higher than the colored layer horizontal plane. In this way, by setting the intersection angle θB between the BM tangent line and the BM upper end surface at the same height as the horizontal plane of the colored layer to be in the vicinity of θI, a colored layer that is horizontal to the peripheral portion and has no uneven thickness can be obtained. I can.

Further, using the color filter formed in the first embodiment of the present invention, a liquid crystal display element was manufactured without forming a smoothing layer. Although a method of making a liquid crystal display element is omitted, a general method of making a TFT liquid crystal display element was used. When the produced liquid crystal display element was checked for the occurrence of a light leakage display defect due to an alignment defect, the display defect did not occur.

Next, the inventors prepared several kinds of BMs having different edge R shapes by changing the developing conditions in the BM forming process by the photolithography method.
Scanning electron microscope (SE
Observe the edge of BM with M), take a photograph, and then measure θB with θ using a protractor and a metal straight scale.
The position of the point P near I was measured, and the results shown in Table 1 were obtained.

Further, a colored layer was formed on the openings of the various BMs by an ink jet method. With respect to all the samples, the thickness of the colored layer was the same as the height of the point P, and the optimum amount of ink was sprayed on each sample. In any of the samples, it was possible to form a color filter having a colored layer with uniform thickness up to the peripheral portion. Subsequently, a liquid crystal display device was manufactured using all the color filter samples prepared. In either case, the flattening layer was not formed. With respect to the various manufactured liquid crystal display elements, it was confirmed whether or not a light leakage display defect occurred due to the alignment defect. The results are also shown in Table 1.

[0030]

[Table 1]

Condition No. Under each of the conditions 1 and 2, a liquid crystal display without light leakage display defects could be obtained.

Condition No. In Nos. 1 and 2, the height difference h between the BM upper end surface and the point P is small, that is, the step difference between the BM upper end surface and the colored layer upper end surface is suppressed to a small level. Therefore, when a liquid crystal display device is produced using this, It was possible to prevent the occurrence of non-uniform orientation due to the step and display a high-quality image.

In condition 3, since the step is too large,
Non-uniform orientation occurs, which causes display failure.

[0034]

EFFECTS OF THE INVENTION According to the present invention, when a liquid crystal display device is manufactured by using a colored layer having a predetermined thickness and having a flat peripheral edge, a display defect such as light leakage occurs. It is possible to provide a color filter capable of preventing the above and displaying an excellent image quality.

Further, it is not necessary to form a flattening layer on the colored layer, and it is possible to provide a low-cost color filter for liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a sectional shape of a black matrix of the present invention.

FIG. 2A is a cross-sectional view of a transparent substrate and a black matrix applied on the transparent substrate according to an embodiment of the present invention. FIG. 2B is a cross-sectional view showing the shape of a black matrix formed after post-baking. Sectional drawing which shows the process of spraying the ink for colored layers to the opening part of a matrix by the inkjet method (d) Cross-sectional view which shows the black matrix and colored layer after an ink spraying process (e) After the drying and hardening process of the ink for colored layers Sectional view showing the black matrix and colored layer of

FIG. 3A is a cross-sectional view of a black matrix and a coloring layer of a color filter of the present invention. FIG. 3B is a cross-sectional view of a black matrix and a coloring layer when θB is smaller than θI in the embodiment of the present invention. Sectional drawing of a black matrix and a coloring layer when (theta) B is larger than (theta) I in embodiment of this invention.

[Explanation of symbols]

1 Transparent Substrate 2 Resin for BM after Full Surface Application 3 BM after Patterning 4 Top Surface 5 of BM 5 Angle of Intersection θ between Top Edge of BM and Edge R Part of BM θ
B 6 Point P 7 where θB is in the vicinity of θI Difference in height between the upper end surface of BM and point P h 8 Inkjet head 9 Ink for colored layer 10 Colored layer before drying 11 Colored layer after drying and curing

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Takahashi             1 Juden Matsushita, 1-8 Koshinmachi, Takamatsu City, Kagawa Prefecture             Child Industry Co., Ltd. F-term (reference) 2H048 BA11 BA45 BA57 BA64 BB01                       BB07 BB28 BB44                 2H091 FA02Y FA35Y FB04 GA13                       LA16

Claims (4)

[Claims] 1. A color filter having a coloring layer in which a coloring layer ink is filled in predetermined openings of a black matrix provided for light shielding, wherein the height of the black matrix is HB, and the height of the coloring layer is HB. Is the difference HB-H between the HB and the HC.
C = h (> 0), the contact angle of the colored layer ink with respect to the black matrix is θI, and the tangent line at the height (HB-h) on the cross section of the black matrix forms the upper surface of the black matrix. Angle θB
And the angle θB and θI are equal to each other. 2. The height of the colored layer is lower than the top surface of the black matrix, and the height difference h thereof is 0.4 μm.
The color filter according to claim 1, wherein the color filter is m or less. 3. The black matrix according to claim 1 or 2, wherein the black matrix has an arc-shaped cross section.
Color filter as described. 4. The ink for the colored layer is a non-aqueous ink containing a pigment or a dye, a photosensitive resin, and an organic solvent for dispersing and dissolving them. The color filter according to claim 3.