JP2008250098A - Color filter, manufacturing method therefor, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a color filter with high productivity, which indicates characteristics superior in the expansion of a view angle from an oblique direction by optimum phase difference compensation in each pixel, and to provide a color filter manufactured by the method and a liquid crystal display provided with such a color filter. <P>SOLUTION: A color filter is manufactured through a process for forming partitions on a substrate, a process for forming liquid crystal phase difference layers corresponding to respective retardations of a plurality of color pixel patterns having prescribed retardations, which are formed thereafter, between the partitions by an ink jet method, and a process for forming the plurality of color pixel patterns, having the prescribed retardations on the liquid crystal phase difference layers by the ink jet method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a color filter and a manufacturing method thereof, and more particularly to a color filter including a phase difference control layer for improving a viewing angle and a liquid crystal display using the color filter.

  Various types of liquid crystal displays have been put into practical use, and these liquid crystal displays are provided with a retardation control layer, but most of them are used in combination with a linear polarizing plate. For example, a circularly polarizing plate combining a linearly polarizing plate and a 1/4 wavelength phase difference plate, or a 1/2 wavelength phase difference plate, a 1/4 wavelength phase difference plate, and a linearly polarizing plate is provided on the observation side of the liquid crystal display. Thus, reflection of external light is prevented and display contrast can be improved.

  In addition, in a reflective liquid crystal display or a transflective liquid crystal display, a circularly polarizing plate or an elliptically polarizing plate is used in order to use the optical shutter effect of liquid crystal molecules.

  Furthermore, a phase difference plate is also used to improve color compensation and viewing angle characteristics of a super twisted nematic mode liquid crystal display. Particularly in recent years, in a vertical alignment mode liquid crystal display capable of high-contrast display, a retardation film (negative C plate) having an optical axis perpendicular to the substrate and having negative birefringence anisotropy, and an optical axis on the substrate. There is an example in which a phase difference film having a positive birefringence anisotropy (positive A plate) is used in combination (for example, see Patent Document 1).

  For the retardation control in these, a retardation control film obtained by stretching a polycarbonate film or the like or a retardation control film obtained by applying a liquid crystal material having birefringence anisotropy to a triacetyl cellulose film or the like is used.

  However, in the above-described conventional retardation film, the retardation is uniform in the plane, and is not set to the optimum retardation for each actually displayed pixel, and the optimum retardation compensation is not necessarily performed. I don't mean.

  One reason for this is that the retardation and refractive index of the liquid crystal itself has a wavelength dependency of the transmitted light, so that the retardation film is required for each color of the pattern constituting the color filter (actually the wavelength of the transmitted light). This is because the retardation used is also different.

On the other hand, an attempt has been made to more optimally perform phase difference compensation by controlling retardation according to the wavelength of transmitted light (see, for example, Patent Document 2).

However, in reality, despite such attempts, when viewing a black display with viewing angle compensation from an oblique direction, there is a problem that it appears reddish purple due to red and blue leakage light. It was.
JP-A-10-153802 JP 2005-148118 A

  The present invention has been made under the circumstances as described above, and efficiently and efficiently manufactures a color filter that exhibits excellent characteristics for widening the viewing angle from an oblique direction by optimal phase difference compensation in each pixel. It aims to provide a method. Another object of the present invention is to provide a color filter manufactured by such a method and a liquid crystal display including such a color filter.

  In order to solve the above-mentioned problem, from the previous studies, the retardation of the color filter layer of each color pixel pattern of red, green and blue is different, red and blue indicate positive retardation, and green indicates negative retardation. However, since the optical design is usually performed with green as the center, if the retardation of the red and blue color filter layers and the green color filter layer are significantly different from each other in positive and negative, the red color is changed as described above. Blue light leaks. The present invention has been made based on such findings.

  According to a first aspect of the present invention, there is provided a step of forming partition walls on a substrate, and a liquid crystal retardation layer corresponding to each retardation of a plurality of colored pixel patterns having a predetermined retardation to be formed later between the partition walls. There is provided a method for producing a color filter, comprising a step of forming a plurality of colored pixel patterns having a predetermined retardation by an ink jet method on the liquid crystal retardation layer.

In such a color filter manufacturing method, the plurality of colored pixel patterns include a red pixel pattern, a blue pixel pattern, and a green pixel pattern, and the red pixel pattern and the blue pixel pattern have a positive retardation, The pixel pattern can have a negative retardation.

  The liquid crystal retardation layer can be composed of a liquid crystal selected from the group consisting of a polymerizable nematic liquid crystal, a polymerizable cholesteric liquid crystal, and a homeotropically aligned polymerizable liquid crystal.

  Further, the liquid crystal retardation layer may include a plurality of liquid crystal retardation regions corresponding to the plurality of colored pixel patterns, and each of the liquid crystal retardation regions may have a different retardation for each of the plurality of colored pixel patterns. .

  In this case, it is desirable that the retardations of the plurality of liquid crystal retardation regions have retardations according to the wavelength range of light passing therethrough.

  In addition, it is desirable that the plurality of liquid crystal retardation regions have a retardation that corrects the retardation of the plurality of colored pixel patterns.

  In the color filter manufacturing method described above, the retardation of the plurality of liquid crystal retardation regions is opposite in sign to the retardation of the colored pixel pattern and can have substantially the same absolute value.

  Moreover, the sum total of the retardation of a several colored pixel pattern and the retardation of the some liquid crystal phase difference area | region corresponding to it can be made substantially the same for every pixel.

The plurality of colored pixel patterns include a red display pixel pattern, a green display pixel pattern, and a blue display pixel pattern. The thickness direction phase difference value R _{Rth of} the red display pixel pattern and the thickness direction phase difference of the green display pixel pattern, respectively. When the value G _Rth and the thickness direction retardation value B _{Rth of the} blue display pixel pattern are used, the following expressions (1) and (2) can be satisfied.
| (R _Rth −B _Rth ) | − | (G _Rth −B _Rth ) | ≧ 0 (1)
| (R _Rth −B _Rth ) | − | (R _Rth −G _Rth ) | ≧ 0 (2)
_{(R Rth, G Rth,} and _{B Rth} is a value obtained by subtracting the thickness direction refractive index from the average in-plane refractive index of each pixel, a numerical value obtained by 1000 times the product of the thickness of the pixel ([mu] m) Represent each.)

  When controlling the retardation of each liquid crystal phase difference region as described above, the plurality of liquid crystal phase difference regions can be constituted by a crosslinked cured product of a polymerizable liquid crystal composition that differs for each of a plurality of colored pixel patterns.

  Alternatively, the plurality of liquid crystal retardation regions can be formed of cross-linked cured products of the same polymerizable liquid crystal composition and have different film thicknesses.

  Furthermore, in the above-described method for producing a color filter, it is desirable that the step of forming the liquid crystal retardation layer includes a step of curing the liquid crystal retardation layer by ultraviolet exposure after applying the liquid crystal retardation layer by an ink jet method.

  According to a second aspect of the present invention, there is provided a color filter manufactured by the method described above.

  According to a third aspect of the present invention, there is provided a liquid crystal display comprising the color filter.

  According to the present invention, since a plurality of colored pixel patterns and a liquid crystal retardation layer are formed by the ink jet method, the environmental load is reduced and the cost is greatly reduced compared to a more general photolithography method. You can go down. In addition, by adjusting the retardation of the liquid crystal retardation layer in accordance with the retardation of each colored pixel pattern, there is no variation in the polarization state of the light passing through the display area of each pixel. A characteristic excellent in enlargement is obtained.

  In addition, since the colored pixel pattern and the liquid crystal retardation layer are formed by an ink jet method, the manufacturing process can be simplified and the materials used can be reduced. Therefore, the cost for manufacturing the color filter can be reduced. .

Furthermore, by performing the formation of the liquid crystal retardation layer by the ink jet method on the substrate prior to the colored pixel pattern, a liquid crystal retardation layer having flatness can be obtained, and the polarization state is less likely to vary, It is possible to provide a color filter having excellent characteristics for widening the viewing angle from an oblique direction.

  In addition, by forming a liquid crystal phase difference layer by the ink jet method and then curing it by UV exposure, a uniform and highly flat liquid crystal phase difference layer can be formed. It can be a filter.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a color filter according to the first embodiment of the present invention. As a transparent substrate, for example, a glass substrate is used. At a position corresponding to the non-pixel portion on the glass substrate 1, a black matrix 2 having a light shielding property as a partition is provided. In addition, as a transparent substrate to be used, an alignment film material was applied on a glass substrate, dried and baked to form an alignment film, and further a rubbing treatment was performed to improve the alignment ability of the liquid crystal material. A substrate may be used.

Phase difference control comprising liquid crystal retardation layers 3 (R), 3 (G), 3 (B) made of a cured product of polymerizable liquid crystal for each pixel in each opening of the black matrix 2 corresponding to the pixel portion. A layer is formed. In addition, on the liquid crystal retardation layer in the opening, the colored pixel patterns of the red pixel pattern 4 (R), the green pixel pattern 4 (G), and the blue pixel pattern 4 (B), all of which are light transmissive, are arranged. Thus, a color filter layer configured as described above is configured.

In the present specification, the polymerizable liquid crystal composition refers to a liquid crystal state that is fixed at room temperature.For example, a liquid crystal monomer having a polymerizable group in its molecular structure is cross-linked to form an optical heterogeneity before cross-linking. Cured while retaining its directivity. Or it aims at the polymer liquid crystal which can freeze a liquid crystal composition by cooling below glass transition temperature.

  Note that the letters R, G, and B represent red, green, and blue in order. The colored pixel pattern may have a colored pixel pattern other than RGB.

  Each of the colored pixel patterns 4 (R), 4 (G), and 4 (B) has a different retardation for each color of red, green, and blue light that passes through each pattern, as shown in FIG. Yes. This retardation shows various values depending on the material, thickness, and processing method of the retardation. From the research so far, the red pixel pattern 4 (R) and the blue pixel pattern 4 (B) have positive retardation. The green pixel pattern 4 (G) has been found to have negative retardation.

  Specifically, the retardation in the thickness direction of the blue pixel pattern 4 (B) is 0.1 nm to 100 nm, the retardation in the thickness direction of the green pixel pattern 4 (G) is −100 nm to −0.1 nm, and red. The retardation in the thickness direction of the pixel pattern 4 (R) is 0.1 nm to 100 nm.

  In order to compensate for the retardation of these colored pixel patterns 4 (R), 4 (G), and 4 (B), the retardation of each liquid crystal phase difference layer is opposite to the retardation of the colored pixel pattern and has an absolute value. Are substantially the same, the retardation of the liquid crystal retardation layer 3 (B) is -100 nm to -0.1 nm, and the retardation of the liquid crystal retardation layer 3 (G) is 0.1 nm to 100 nm. The retardation of the liquid crystal retardation layer 3 (R) is preferably from −100 nm to −0.1 nm.

  The liquid crystal materials constituting the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) are nematic liquid crystal material, cholesteric liquid crystal material, or homeo so as to have retardation corresponding to the wavelength range of light passing through each layer. It is preferable to appropriately select a tropic-aligned polymerizable liquid crystal material.

  That is, the liquid crystal material constituting the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) may be any material that has a function of giving a phase difference to light incident at a certain incident angle. Not only the nematic liquid crystal described above, but also any liquid crystal material such as a chiral nematic liquid crystal (a nematic liquid crystal with a chiral agent added) can be used.

  The nematic liquid crystal preferably has a polymerizable group. The chiral agent also preferably has a polymerizable group. As for the chiral nematic liquid crystal, it is preferable to use nematic liquid crystals alone or as a mixture of two or more nematic liquid crystals as necessary.

  Next, with reference to FIG. 3, the manufacturing method of the color filter with a phase difference control layer shown in FIG. 1 will be described.

  First, as shown in FIG. 3A, a black matrix 2 for improving contrast is provided on a transparent substrate 1.

  As the transparent substrate 1, a known transparent substrate material such as a glass substrate, a quartz substrate, or a plastic substrate can be used. Among them, the glass substrate is excellent in transparency, strength, heat resistance, and weather resistance.

  The black matrix 2 can be formed using a known method. For example, a method of forming a metal or metal oxide thin film on a substrate by a method such as sputtering, and patterning it by a method such as etching; a colorant such as a pigment or a dye in the photosensitive resin composition A method of forming a photosensitive resin composition on a substrate and forming it by a photolithography method; a method of forming a black pigment or a thermosetting resin in a solvent and forming it by a printing method, or the like. The black matrix 2 desirably contains an ink repellent agent for preventing color mixing. Color mixing occurs when color ink penetrates into color ink in adjacent pixels.

  Examples of the ink repellent agent include silicone materials and fluorine materials. Specifically, a silicone resin or silicone rubber having an organosilicone or alkylfluoro group in the main chain or side chain and containing a siloxane component, in addition to vinylidene fluoride, vinyl fluoride, ethylene trifluoride, etc. Fluorine resins such as these copolymers can be used. Ink repellent bleeds out during the heating process, and the ink repellent adheres to the transparent substrate, and color loss may occur when filling with color ink. As the agent, a fluorine-containing compound is preferably used. In order to prevent bleeding out, it is preferable to use an oligomer compound rather than a low molecular compound.

  Next, as shown in FIG. 3B, a different liquid crystal phase difference layer 3 (R), 3 (R), 3 (R), 3 (R), (G) and 3 (B) are formed. As the liquid crystal composition, a nematic liquid crystal material, a cholesteric liquid crystal material, or a homeotropically aligned polymerizable liquid crystal material is appropriately selected so as to have retardation corresponding to the wavelength range of light passing through each layer.

Next, as shown in FIG. 3 (c), liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) formed by an ink jet method in the openings of the black matrix 2 The liquid crystal composition is crosslinked and cured by irradiating an irradiation amount of ultraviolet rays. In addition, when the ultraviolet rays irradiated to the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) cure the liquid crystal composition, a photopolymerization initiator may be added to the liquid crystal composition. preferable. The dose of ultraviolet rays, the presence or amount of the photopolymerization initiator, or varies depending on the radiation type and intensity, is preferably about the range of, for example, ^{1mJ / cm 2 ~10000mJ / cm 2} . Moreover, it is preferable that the atmosphere which irradiates an ultraviolet-ray is inert gas atmosphere, such as nitrogen. By irradiating ultraviolet rays in such an atmosphere, the liquid crystal composition can be cured without being affected by oxygen, and the optical characteristics of the liquid crystal layer can be stabilized. Furthermore, it is preferable to uniformly control the temperature of the atmosphere in which the ultraviolet rays are irradiated at a temperature higher than room temperature. Thereby, polymerization of the liquid crystal composition at the time of ultraviolet irradiation can be promoted, and the optical characteristics of the liquid crystal layer can be stabilized.

  Further, the liquid crystal phase difference layer is baked at a predetermined temperature and additionally cured to stabilize the optical characteristics of the liquid crystal layer. At this time, it is possible to heat the liquid crystal retardation layer at a high temperature to cause a thermal effect, but because of stabilization of the optical properties of the liquid crystal composition and the risk of bleeding out of the ink repellent agent from the black matrix. It is desirable that it is 100 to 200 ° C.

  As an apparatus used for the ink jet method for forming the liquid crystal composition region, there are a piezo conversion method and a heat conversion method depending on a discharge method, but it is desirable to use a piezo conversion method apparatus. Further, the particle formation frequency of the liquid crystal composition in the ink jet apparatus is desirably about 5 to 100 KHz. The nozzle diameter in the ink jet apparatus is desirably about 5 to 80 μm. Further, it is preferable to use an ink jet apparatus in which a plurality of heads are arranged and about 60 to 500 nozzles are incorporated in one head.

  Next, as shown in FIG. 3D, red (R), green (G), and blue (B) colored pixel patterns on the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B). 4 (R), 4 (G), and 4 (B) are formed. In this embodiment, a color ink is formed in a pattern by an ink jet apparatus, and then colored pixel patterns 4 (R), 4 (G), and 4 (B) are formed through a heating process described later.

  As the colorant of the color ink, pigments, dyes and the like can be used. In the present invention, it is preferable to use a pigment having excellent weather resistance. The thermosetting resin used for the color ink is appropriately selected from materials used for manufacturing a known color filter substrate in relation to the pigment. Specifically, casein, gelatin, polyvinyl alcohol, carboxymethyl acetal, polyimide resin, acrylic resin, epoxy resin, miramin resin, or the like can be used. In particular, when manufacturing a color filter that requires heat resistance and light resistance, it is preferable to use an acrylic resin.

  The solvent used for the color ink is selected according to the printing suitability of the ink jet apparatus, and it is particularly preferable to use a material having a surface tension range of less than 35 mN / m and a boiling point of 130 ° C. or higher. When the surface tension is 35 mN / m or more, the dot shape stability during ink jet ejection is adversely affected. Further, when the boiling point is lower than 130 ° C., the drying property near the nozzle is increased. As a result, there is a possibility of causing a defect such as nozzle clogging, which is not preferable. Moreover, the solvent can mix and adjust 2 or more types of solvents so that it may meet the said conditions as needed, and can use it.

  The color ink dispersant is used to improve the dispersion of the pigment in the resin. As the dispersant, an ionic or nonionic surfactant or the like can be used. Specific examples include sodium alkylbenzene sulfonate, poly fatty acid salts, fatty acid salt alkyl phosphates, tetraalkyl ammonium salts, polyoxyethylene alkyl ethers, and other organic pigment derivatives and polyesters. One type of dispersant may be used alone, or two or more types of dispersants may be mixed and used.

  As an apparatus used in the ink jet method for forming the colored pixel pattern, there are a piezo conversion method and a heat conversion method depending on the ejection method, but it is desirable to use a piezo conversion method apparatus. In addition, the ink particle frequency in the ink jet apparatus is preferably about 5 to 100 KHz. The nozzle diameter in the ink jet apparatus is desirably about 5 to 80 μm. Further, it is preferable to use an ink jet apparatus in which a plurality of heads are arranged and about 60 to 500 nozzles are incorporated in one head.

  Finally, the substrate on which the colored pixel pattern is formed on the liquid crystal retardation layer is baked and cured at a predetermined temperature. Note that the firing temperature at this time is desirably 150 ° C. to 250 ° C.

  As a result, finally, as shown in FIG. 3 (d), the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) having retardation corresponding to the display areas of the respective colors of the pixels. A phase difference control layer is formed, and a color filter with a liquid crystal phase difference layer is completed.

  As described above, as the liquid crystal composition that differs from pixel to pixel, the liquid crystal phase difference layer 3 (R) is a liquid crystal composition having a retardation of −100 to −0.1 nm, and the liquid crystal phase difference layer. A liquid crystal composition having a retardation of 0.1 nm to 100 nm is selected for 3 (G), and a liquid crystal composition having a retardation of −100 to −0.1 nm is selected for the liquid crystal retardation layer 3 (B). To do.

  As described above, according to the first embodiment, the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) are adjusted to have retardation corresponding to the wavelength range of light. Therefore, there is no variation in the polarization state of light passing through the display area of each color of the pixel. Furthermore, since the display is black with the viewing angle compensated from the oblique direction, when viewed from the oblique direction, the color shift can be reduced and the neutral black can be reproduced, and the display characteristics are excellent. be able to.

  FIG. 4 is a sectional view showing a color filter according to the second embodiment of the present invention. In FIG. 4, a black matrix 2 made of a light-shielding material is provided at a position corresponding to a non-pixel portion on the glass substrate 1, and a liquid crystal retardation layer is formed in each opening of the black matrix 2 corresponding to the pixel portion. And a color filter layer in which each color pixel pattern of the red pixel pattern 4 (R), the green pixel pattern 4 (G), and the blue pixel pattern 4 (B), which are light transmissive, is arranged. This is the same as the color filter according to the embodiment shown in FIG.

  The color filter according to the present embodiment is different from the color filter according to the embodiment shown in FIG. 1 in that, in the color filter according to the embodiment shown in FIG. While the liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) having retardation corresponding to the wavelength range of light passing through the liquid crystal are formed, in the color filter according to the present embodiment, The same polymerizable liquid crystal composition is laminated also in the pixels of, and the liquid crystal retardation layers 13 (R), 13 (G), and 13 having different film thicknesses so as to have retardation corresponding to the wavelength range of light passing through each layer. (B) is formed.

  In this case, the retardation in the thickness direction of the liquid crystal retardation layers 13 (R), 13 (G), and 13 (B) and the thickness direction of each colored pixel pattern 4 (R), 4 (G), and 4 (B). It is preferable that the sum of retardation is equal to each other for each pixel. The specific value differs according to the value of retardation in the thickness direction of each colored pixel pattern 4 (R), 4 (G), 4 (B).

  For example, the retardation in the thickness direction of the blue pixel pattern 4 (B) was 5 nm, the retardation in the thickness direction of the green pixel pattern 4 (G) was −40 nm, and the retardation in the thickness direction of the red pixel pattern 4 (R) was 10 nm. In this case, for example, if the retardation of the liquid crystal retardation layer 13 (B) is 15 nm, the retardation of the liquid crystal retardation layer 13 (G) is 60 nm, and the retardation of the liquid crystal retardation layer 13 (R) is 10 nm, each colored pixel The sum of the retardation in the thickness direction of the patterns 4 (R), 4 (G), and 4 (B) and the retardation in the thickness direction of the liquid crystal retardation layers 13 (R), 13 (G), and 13 (B) is 20 nm. And become equal to each other.

  The retardation of each liquid crystal phase difference layer 13 (R), 13 (G), 13 (B) is represented by the product of the refractive index anisotropy Δn in the thickness direction and the film thickness d. Since Δn is constant for the same polymerizable liquid crystal composition, the retardation of the liquid crystal retardation layers 13 (R), 13 (G), and 13 (B) can be controlled by the film thickness.

  The retardation in the thickness direction of the liquid crystal retardation layers 13 (R), 13 (G), and 13 (B) and the retardation in the thickness direction of the colored pixel patterns 4 (R), 4 (G), and 4 (B). The total value is not particularly limited as long as it is equal to each other for each pixel. However, the absolute value is preferably closer to 0 in order not to significantly deteriorate the characteristics of the final liquid crystal display. Therefore, in the above-described example, for example, the retardation of the liquid crystal retardation layer 13 (B) is 5 nm, the retardation of the liquid crystal retardation layer 13 (G) is 50 nm, and the retardation of the liquid crystal retardation layer 13 (R) is 0 nm. For example, the sum of the retardation in the thickness direction of each of the liquid crystal retardation layers 13 (R), 13 (G), and 13 (B) and the retardation in the thickness direction of each colored pixel pattern is equal to each other at 10 nm, which is more preferable. . At this time, since the retardation of the liquid crystal retardation layer 13 (R) is 0 nm, the thickness of the liquid crystal retardation layer 13 (R) is 0, which means that the liquid crystal retardation layer 13 (R) is not provided. It becomes.

  Thus, according to the value of the retardation in the thickness direction of each colored pixel pattern, the total of the retardation in the thickness direction of the liquid crystal retardation layer region corresponding to each colored pixel pattern is equal to each other for each pixel. By controlling the film thickness of the liquid crystal retardation region, the degree of retardation of each colored pixel pattern is equal even when viewed from an oblique direction, so that the hue of each colored pixel pattern does not vary, and optimal retardation is achieved. Correction can be performed.

  The color filter according to the second embodiment shown in FIG. 4 described above can be manufactured in the same manner as the manufacturing process shown in FIG. However, it is necessary to appropriately control the discharge amount of the liquid crystal composition for each pixel so that a liquid crystal phase difference layer having a film thickness corresponding to the necessary retardation is formed. Naturally, the liquid crystal composition is not discharged to the pixel portion that does not require the liquid crystal retardation layer.

Further, the absolute value of the birefringence index of the color filter as described above, is 0.01 or less, that the thickness direction retardation _{R th} for the colored pixel pattern, infinitely _{R Rth =} G Rth _{= B} Rth Although it is desired to be close to 0, when combined with wavelength dispersibility of retardation such as a component other than a color filter, such as a liquid crystal, a polarizing plate, and an alignment film, R _Rth = G _Rth = B _Rth = 0 In addition to the case, there is an optimum thickness direction retardation value of the color filter.

Therefore, the most desirable value for the phase difference value _Rth of each color display pixel in the color filter varies depending on the combination with other members. However, it is important that _GRth is equal to or greater than _{RRth. Nevertheless,} state and _{B Rth} is less than _{G Rth,} that _{G Rth} despite or less _{R Rth,} state _{B Rth} is greater than or equal to _{G Rth} can not obtain a good oblique visibility Is a point. This is because in other members used in the liquid crystal display device, the birefringent wavelength dispersibility continuously changes with respect to the wavelength of transmitted light.

Therefore, each color display pixel thickness direction retardation R _th, i.e., the thickness direction retardation value of the red display pixel 3R RRTH, green display pixel 3G in the thickness direction retardation value G _Rth, and the thickness direction of the blue display pixel 3B It is desirable that the phase difference value _BRth satisfies the following formulas (1) and (2).

| (R _Rth −B _Rth ) | − | (G _Rth −B _Rth ) | ≧ 0 (1)
| (R _Rth −B _Rth ) | − | (R _Rth −G _Rth ) | ≧ 0 (2)

The formula (1) and (2), whether positive or negative _sign, if _{G Rth} is more than _{R Rth is B Rth} is at least _{G Rth,} when _{G Rth} is less than _{R Rth} is , _{B Rth} means that is less than _{G Rth.} That is, there is _GRth between _RRth and _BRth .

Thus, by using a color filter in which the thickness direction retardation value Rth of each colored display pixel satisfies the above-described conditions, a liquid crystal display device having good oblique visibility can be obtained.

  Hereinafter, although the more concrete Example about embodiment described above is shown, this invention is not limited to these Examples. Further, since the material used in the present invention is extremely sensitive to light, it is necessary to prevent exposure to unnecessary light such as natural light, and all operations were performed under a yellow or red light.

[Example 1]
<Confirmation of effect of liquid crystal retardation layer>
A liquid crystal composition (i) was prepared by dissolving 100 parts by weight of nematic liquid crystal having a polymerizable liquid crystal and 5 parts by weight of a photoinitiator in 420 parts of toluene. This liquid crystal composition (i) was mixed with 9 parts by weight of a chiral agent to obtain a liquid crystal composition (ii). The nematic liquid crystal in the liquid crystal composition (i) was replaced with a nematic liquid crystal having a higher birefringence, and the liquid crystal composition (iii) was adjusted at the same mixing ratio.

First, a liquid crystal retardation layer was formed by spin coating the liquid crystal composition (ii) on a glass substrate. The film thickness of the liquid crystal retardation layer after heating at 60 ° C. for 1 minute was 0.7 μm. Next, the liquid crystal retardation layer was exposed at an irradiation amount of 1000 mJ / cm ² by an ultraviolet irradiation device using an ultrahigh pressure mercury lamp as a light source. In addition, the exposure process was implemented in nitrogen atmosphere so that superposition | polymerization inhibition by the oxygen in air | atmosphere might not arise.

  Furthermore, in order to stabilize the liquid crystal retardation layer, a liquid crystal retardation layer was formed by a heating process at 150 ° C. for 30 minutes. It was 40 nm when the retardation of the thickness direction of this liquid crystal phase difference layer was measured.

Similarly, a liquid crystal retardation layer was formed by spin coating the liquid crystal composition (i) and the liquid crystal composition (iii) on a glass substrate. The film thickness of the liquid crystal retardation layer after heating at 60 ° C. for 1 minute was 0.7 μm. Next, the liquid crystal retardation layer was exposed at an irradiation amount of 1000 mJ / cm ² by an ultraviolet irradiation device using an ultrahigh pressure mercury lamp as a light source. In addition, the exposure process was implemented in nitrogen atmosphere so that superposition | polymerization inhibition by the oxygen in air | atmosphere might not arise.

  Furthermore, in order to stabilize the liquid crystal retardation layer, a liquid crystal retardation layer was formed by a heating process at 150 ° C. for 30 minutes.

  When the retardation in the thickness direction of the liquid crystal retardation layer was measured, the substrate in which the liquid crystal retardation layer was formed from the liquid crystal composition (i) was -5 nm, and the substrate in which the liquid crystal retardation layer was formed from the liquid crystal composition (iii). In -20 nm.

<Production of color filter>
(Formation of black matrix)
10 parts by weight of a polyimide precursor (Semicofine SP-510: manufactured by Toray Industries, Inc.), 7.5 parts by weight of carbon black, 130 parts by weight of NMP, 5 parts by weight of a dispersant (copper phthalocyanine derivative), 5 parts by weight of initiator A, and A black matrix composition was prepared by dispersing 0.1 part by weight of a perfluoroalkyl group-containing oligomer (FTX-720C: manufactured by Neos Co., Ltd.) for 3 hours while cooling with a bead mill disperser.

  This black matrix composition was applied onto a non-alkali glass substrate (product number 1737: manufactured by Corning) using a spin coater to form a coating film having a thickness of about 2.0 μm. Then, after pre-baking at 100 ° C. for 20 minutes, through an exposure / development step, post-baking is performed at 230 ° C. for 60 minutes, and as shown in FIG. Black matrix 2 was formed.

The contact angle to the colored ink (surface tension 30 mN / m) at the top of the black matrix 2 formed in this way was measured and found to be 30 °, and the top of the black matrix was ink repellent with respect to the colored ink. Confirmed that there is.
(Formation of liquid crystal retardation layer)

  A colored pixel pattern 4 (G) is formed on the liquid crystal composition (ii) by an ink jet apparatus in which a 108 pl, 150 dpi head (manufactured by Seiko Innsmelts) is mounted in the opening of the black matrix 2 on the glass substrate 1. The area enclosed by the partition walls to be filled was filled. The film thickness of the liquid crystal retardation layer after heating at 60 ° C. for 1 minute was 0.7 μm.

Next, the filled liquid crystal retardation layer was exposed with an irradiation amount of 1000 mJ / cm ² by an ultraviolet irradiation device using an ultrahigh pressure mercury lamp as a light source. Furthermore, in order to stabilize the liquid crystal retardation layer, a heating process was performed at 150 ° C. for 30 minutes to form a liquid crystal retardation layer 3 (G).

  Further, using the liquid crystal compositions (i) and (iii), the colored pixel patterns 4 (B) and 4 (R) should be formed by the same apparatus as that for forming the liquid crystal composition (ii). Each was filled in a region surrounded by a partition wall. The film thickness after heating at 60 ° C. for 1 minute was 0.7 μm.

Next, the filled liquid crystal retardation layer was exposed with an irradiation amount of 1000 mJ / cm ² by an ultraviolet irradiation device using an ultrahigh pressure mercury lamp as a light source. Furthermore, in order to stabilize the liquid crystal retardation layer, a heating process was performed at 150 ° C. for 30 minutes to form liquid crystal retardation layers 3 (B) and 3 (R).

(Color ink adjustment)
[Production of coloring material]
The following were used as the coloring agents for coloring the coloring material used for producing the color filter.

Red pigment: C.I. I. Pigment Red 254 (“Ilgar Forred B-CF” manufactured by Ciba Special Chemicals), and C.I. I. Pigment Red 177 ("Chromoval Red A2B" manufactured by Ciba Special Chemicals)
Green pigment: C.I. I. Pigment Green 36 (“Lionol Green 6YK” manufactured by Toyo Ink) and C.I. I. Pigment Yellow 150 (Bayer's “Funcheon First Yellow Y-5688”)
Blue pigment: C.I. I. Pigment Blue 15 (“Rionol Blue ES” manufactured by Toyo Ink Co., Ltd.) C.I. I. Pigment Violet 23 (manufactured by BASF “Paliogen Violet 5890”)
Also, 20 parts of methacrylic acid, 10 parts of methyl methacrylate, 55 parts of butyl methacrylate and 15 parts of hydroxyethyl methacrylate are dissolved in 300 g of butyl lactate, and 0.75 part of azobisisobutylnitrile is added under a nitrogen atmosphere, and 5 parts at 70 ° C. An acrylic copolymer resin was prepared by reaction over time. The obtained acrylic copolymer resin was diluted with diethylene glycol monomethyl ether so as to have a resin concentration of 20% to obtain an acrylic varnish.

  Using the above pigments and acrylic varnish, red, green, and blue coloring materials were produced as follows.

-Red coloring material After uniformly stirring and mixing a mixture having the composition shown below, using a glass bead having a diameter of 1 mm, dispersing it with a sand mill for 5 hours, and then filtering with a 5 μm filter to produce a red pigment dispersion. did.

Red pigment: C.I. I. Pigment Red 254 18 parts by weight Red pigment: C.I. I. Pigment Red 177 2 parts by weight Acrylic varnish: (solid content 20%) 108 parts by weight Then, the mixture having the composition shown below was stirred and mixed uniformly, and then filtered through a 5 μm filter to obtain a red colored material. It was.

The dispersion 128 parts by weight Diethylene glycol monomethyl ether 50 parts by weight Tetraethylene glycol dimethyl ether 30 parts by weight Green coloring material Each of the dispersions was prepared in the same manner as the red coloring material so as to have the following composition.

Green pigment: C.I. I. Pigment Green 36 16 parts by weight Yellow pigment: C.I. I. Pigment Yellow 150 8 parts by weight Acrylic varnish: (solid content 20%) 102 parts by weight Diethylene glycol monomethyl ether 50 parts by weight Tetraethylene glycol dimethyl ether 30 parts by weight Blue coloring material Same as the red coloring material so as to have the following composition It was produced by the method.

Blue pigment: C.I. I. Pigment Blue 15 50 parts by weight Purple pigment: C.I. I. Pigment Violet 23 2 parts by weight Dispersant: “Sols Birds 20000” manufactured by Zeneca Co., Ltd. 6 parts by weight Acrylic varnish (solid content 20%) 200 parts by weight Diethylene glycol monomethyl ether 100 parts by weight Tetraethylene glycol dimethyl ether 60 parts by weight (Preparation of color filter substrate)
On the liquid crystal retardation layer formed in the opening portion of the black matrix 2 on the glass substrate 1, the color inks of the R, G, and B colors are used, and 108 dpi and 150 dpi heads (manufactured by Seiko Instruments Inc.) are mounted. Liquid crystal phase difference layers 3 (R), 3 (G) and 3 (3) formed in an area surrounded by red (R), green (G) and blue (B) partition walls by an ink jet printer. B) Filled on top. Then, it is heated at 200 ° C. for 30 minutes on a hot plate to form colored pixel patterns 4 (R), 4 (G), and 4 (B) as shown in FIG. It was.

  The retardations in the thickness direction of these colored pixel patterns 4 (R), 4 (G), and 4 (B) are 20 nm, −45 nm, and 4 nm, respectively. The retardation in each pixel is the sum of the retardation of the colored pixel pattern and the liquid crystal retardation layer, that is, 0 nm in the colored pixel (R) portion, -5 nm in the colored pixel (G) portion, and -1 nm in the colored pixel (B) portion. Estimated

[Comparative Example 1]
A color filter was produced in the same manner as in Example 1 except that the liquid crystal retardation layer was not provided.

  The color filters of Example 1 and Comparative Example 1 obtained as described above are sandwiched by two deflection films arranged so that the deflection axes are parallel and orthogonal, and a three-wavelength tube backlight (Tc) is provided on the back surface. = 6000K) was installed, and chromaticity measurement was performed from the front direction and an oblique 45 ° direction using a luminance meter (product number BM-5A: manufactured by Topcon Corporation). The results are shown in Tables 1 and 2 below. Table 1 shows the result of chromaticity measurement from the front direction, and Table 2 shows the result of chromaticity measurement from an oblique 45 ° direction. 4 and 5 are characteristic diagrams in which Tables 1 and 2 are plotted on the xy coordinates.

  As shown in the results of Tables 1 and 2 above, no significant change was observed in the appearance and chromaticity from the front direction, but in the oblique 45 ° direction, a reddish purple color was exhibited in the comparative example. In Example 1, it was confirmed that an achromatic gray was obtained by providing a liquid crystal retardation layer and performing phase difference control.

[Example 2]
<Production of phase-controlled color filter>
(Adjustment of liquid crystal composition and calculation of relationship between film thickness and phase difference)
A liquid crystal composition (i) was prepared by dissolving 100 parts by weight of a nematic liquid crystal having a polymerizable group, 9 parts by weight of a chiral agent, and 5 parts by weight of a photoinitiator in 420 parts of toluene.

First, the liquid crystal composition (i) was applied on the glass substrate 1 by spin coating. Heating was performed at 60 ° C. for 1 minute, and then exposure was performed at an irradiation amount of 1000 mJ / cm ² by an ultraviolet irradiation device using an ultrahigh pressure mercury lamp as a light source. The exposure process was performed under a nitrogen atmosphere so as not to cause polymerization inhibition due to oxygen in the atmosphere. Furthermore, in order to stabilize the liquid crystal retardation layer, a liquid crystal retardation layer was formed through a heating process at 150 ° C. for 30 minutes. The film thickness of the formed liquid crystal retardation layer was 0.7 μm.

  It was 35 nm when the retardation of the thickness direction of the said liquid crystal phase difference layer was measured. Therefore, it was found that the retardation per 1 μm of the liquid crystal retardation layer was 50 nm.

<Formation of liquid crystal retardation layer>
In the same manner as in Example 1, the liquid crystal composition (i) was filled into the opening of the black matrix on the produced glass substrate 1 by an ink jet printing apparatus.

Next, exposure was performed at an irradiation amount of 1000 mJ / cm ² using an ultraviolet irradiation apparatus using ultrahigh pressure mercury or the like as a light source. Further, a heating process is performed at 150 ° C. for 30 minutes for stabilization, and as shown in FIG. 4, a retardation control region composed of liquid crystal retardation layers 13 (R), 13 (G), and 13 (B) is formed. did.

  The filling amount of the liquid crystal composition (i) is 0.2 μm for the liquid crystal retardation layer 13 (R), 1.5 μm for the liquid crystal retardation layer 13 (G), and the liquid crystal retardation layer 13. About (B), it adjusted by controlling the discharge amount in an ink jet printer so that a film thickness might be set to 0.5 micrometer.

  On the liquid crystal retardation layer formed in the opening of the black matrix 2 on the glass substrate 1, the color inks of the R, G, and B colors are used, and red (R), green ( The liquid crystal retardation layers 3 (R), 3 (G), and 3 (B) formed in the regions surrounded by the partition walls of G) and blue (B) were filled. Then, it heated at 200 degreeC with the hotplate for 30 minutes, and obtained the color filter substrate which formed the colored pixel pattern 4 (R), 4 (G), 4 (B).

  The retardation of only the liquid crystal retardation layer by the liquid crystal composition (i) is 10 nm for the liquid crystal retardation layer 13 (R), 75 nm for the liquid crystal retardation layer 13 (G), and 25 nm for the liquid crystal retardation layer 13 (B). In each pixel, the sum of the phase differences from the respective colored pixel patterns is 30 nm in the colored pixel (R) portion, 30 nm in the colored pixel (G) portion, and 29 nm in the colored pixel (B) portion, which are substantially the same.

  The color filter of Example 2 obtained as described above is sandwiched between two deflection films arranged so that the deflection axes are parallel and orthogonal, and a three-wavelength tube backlight (Tc = 6000K) is provided on the back surface. It installed, and the chromaticity measurement was performed from the front direction and 45 degrees diagonal direction using the luminance meter (product number BM-5A: Topcon Co., Ltd. product). The results are shown in Tables 3 and 4 below together with the results of Comparative Example 1. Table 3 shows the result of the chromaticity measurement from the front direction, and Table 4 shows the result of the chromaticity measurement from the oblique 45 ° direction. 7 and 8 are characteristic diagrams in which Tables 3 and 4 are plotted on the xy coordinates.

  As shown in the results of Tables 3 and 4 above, no major changes were observed in the appearance and chromaticity from the front direction, but in the oblique 45 ° direction, a reddish purple color was exhibited in the comparative example. However, it was confirmed that an achromatic gray color was obtained by providing a liquid crystal retardation layer in Example 2 and performing phase difference control.

1 is a schematic cross-sectional view showing a color filter including a liquid crystal retardation layer according to a first embodiment of the present invention. The figure which shows the retardation of the coloring fine pattern of a color filter. Sectional drawing for demonstrating the manufacturing process of the color filter provided with the liquid crystal phase difference layer shown in FIG. 1 is a schematic cross-sectional view showing a color filter including a liquid crystal retardation layer according to a first embodiment of the present invention. FIG. 6 is a characteristic diagram showing the results of chromaticity measurement from the front direction of the color filters according to Example 1 and Comparative Example 1. FIG. 6 is a characteristic diagram showing the result of chromaticity measurement performed from an oblique 45 ° direction of the color filters according to Example 1 and Comparative Example 1. FIG. 6 is a characteristic diagram showing the results of chromaticity measurement from the front direction of the color filters according to Example 2 and Comparative Example 1. FIG. 6 is a characteristic diagram showing the result of chromaticity measurement performed from an oblique 45 ° direction of the color filters according to Example 2 and Comparative Example 1.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Partition black matrix, 3 (R), 3 (G), 3 (B), 13 (R), 13 (G), 13 (B) ... Liquid crystal phase difference Layer, 4 (R) ... Red pixel pattern, 4 (G) ... Green pixel pattern, 4 (B) ... Blue pixel pattern

Claims (14)

  A step of forming partition walls on the substrate, a step of forming a liquid crystal retardation layer corresponding to each retardation of a plurality of colored pixel patterns having a predetermined retardation to be formed between the partition walls by an ink jet method, the liquid crystal position A method for producing a color filter, comprising a step of forming a plurality of colored pixel patterns having a predetermined retardation on a phase difference layer by an ink jet method.   The plurality of colored pixel patterns include a red pixel pattern, a blue pixel pattern, and a green pixel pattern, wherein the red pixel pattern and the blue pixel pattern have a positive retardation, and the green pixel pattern has a negative retardation. The method for producing a color filter according to claim 1.   The liquid crystal retardation layer is made of a liquid crystal selected from the group consisting of a polymerizable nematic liquid crystal, a polymerizable cholesteric liquid crystal, and a homeotropically aligned polymerizable liquid crystal. Manufacturing method of color filter.   The method for producing a color filter according to claim 1, wherein the plurality of liquid crystal retardation regions are crosslinked cured products of different polymerizable liquid crystal compositions for the plurality of colored pixel patterns.   The method for producing a color filter according to claim 1, wherein the plurality of liquid crystal retardation regions are made of a crosslinked cured product of the same polymerizable liquid crystal composition and have different film thicknesses.   The liquid crystal retardation layer includes a plurality of liquid crystal retardation regions corresponding to the plurality of colored pixel patterns, and each of the liquid crystal retardation regions has a different retardation for each of the plurality of colored pixel patterns. The manufacturing method of the color filter of Claim 1 to 5.   The method for producing a color filter according to claim 6, wherein the retardation of the plurality of liquid crystal retardation regions has retardation corresponding to a wavelength region of light passing therethrough.   The method for manufacturing a color filter according to claim 6 or 7, wherein the plurality of liquid crystal phase difference regions have retardation for correcting retardation of the plurality of colored pixel patterns.   The method for producing a color filter according to claim 6, wherein the retardation of the plurality of liquid crystal retardation regions has an opposite sign and substantially the same absolute value as the retardation of each colored pixel pattern. .   9. The method for manufacturing a color filter according to claim 6, wherein the sum of the retardation of each colored pixel pattern and the corresponding retardation of the liquid crystal retardation region is substantially the same in each pixel. The colored pixel pattern, red display pixel pattern includes a green display pixel pattern and a blue display pixel pattern, the thickness direction retardation value R _Rth of the red display pixel _pattern, the thickness direction retardation value of the green display pixel pattern G _Rth The thickness direction retardation value _{BRth of the} blue display pixel pattern satisfies the following formulas (1) and (2), and the method of manufacturing a color filter according to claim 6:
| (R _Rth −B _Rth ) | − | (G _Rth −B _Rth ) | ≧ 0 (1)
| (R _Rth −B _Rth ) | − | (R _Rth −G _Rth ) | ≧ 0 (2)
_{(R Rth, G Rth,} and _{B Rth} is a value obtained by subtracting the thickness direction refractive index from the average in-plane refractive index of each pixel, a numerical value obtained by 1000 times the product of the thickness of the pixel ([mu] m) Represent each.)   12. The color according to claim 1, wherein the step of forming the liquid crystal retardation layer includes a step of curing the liquid crystal retardation layer by ultraviolet exposure after coating the liquid crystal retardation layer by an ink jet method. A method for manufacturing a filter.   A color filter manufactured by the method according to claim 1.   A liquid crystal display comprising the color filter according to claim 13.