JP2003075821A - Color filter for liquid crystal display device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively obtain a color filter for a semitransmission type liquid crystal display device being nearly free from the difference of chromaticity between the cases of a reflection mode and a transmission mode, having excellent white balance and capable of giving bright reflection display and to obtain the semitransmission type liquid crystal display device. SOLUTION: The color filter for the liquid crystal display device containing a transmitting area and a reflecting area has a blue pixel consisting of two or more colored layers. The semitransmission type liquid crystal display device is provided with the color filter and a three wavelength type white LED.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter and a liquid crystal display device using the same, and more particularly to a transflective liquid crystal display device and a reflective liquid crystal display device, and a semi-transmissive liquid crystal display device having both characteristics. Is.

[0002]

2. Description of the Related Art At present, liquid crystal display devices, which are lightweight, thin, and have low power consumption, are used for notebook PCs, portable information terminals,
It is used in various applications such as desktop monitors and digital cameras. In a liquid crystal display device using a backlight, it is required to enhance the utilization efficiency of the backlight light in order to reduce the power consumption, and it is required to increase the transmittance of the color filter. On the other hand, although the transmittance of color filters is increasing year by year, it is becoming difficult to expect a significant reduction in power consumption due to the improvement in transmittance. Recently, the development of a reflective liquid crystal display device that does not require a backlight light source that consumes a large amount of power is underway, and it is possible to significantly reduce the power consumption to about 1/7 that of a transmissive liquid crystal display device. Has been announced (Nikkei Microdevices Separate Volume Flat Panel Display 1998, P.
126).

The reflective liquid crystal display device consumes less power than the transmissive liquid crystal display device and has the advantage of being excellent in outdoor visibility, but the display is dark in a place where sufficient ambient light intensity is not secured. Therefore, there is a problem that the visibility is extremely deteriorated. In order to make the display visible even in a dark environment, (1) a backlight is provided,
A liquid crystal display device in which a notch is formed in a part of a reflective film, a part of which is a transmissive display system and a part of which is a reflective display system (so-called transflective transflective display system, as a document, for example, Fine Process Technology Japan ' 99, technical seminar text A5), and (2) a liquid crystal display device provided with a front light has been devised.

A backlight light source used in a mobile terminal,
As the front light source, there are a three-wavelength type fluorescent tube and a white LED which is advantageous for downsizing and thinning. The three-wavelength fluorescent tube is advantageous in terms of power consumption and is known to improve the color reproducibility of transmitted colors, and is used for mobile PCs, PDAs, etc., which are relatively large as mobile terminals. ing.

A white LED has a spectrum shape of 2
It is divided into wavelength type and three wavelength type. Dual wavelength white LED
Is white by combining a blue LED and a phosphor (FIG. 4), and a three-wavelength white LED is a combination of an ultraviolet LED and a red-green-blue phosphor (FIG. 2), or three-color LE of red-green-blue.
The combination of D is white (Fig. 3). As it stands, the white LED light source is a dual wavelength white L
ED has been used as almost the only option (Nikkei Electronics, 2-25, 2002).

In a semi-transmissive liquid crystal display device provided with a backlight, a transmissive display using the backlight light and a reflective display using the ambient light coexist, but when the transmissive display is performed, the backlight light causes the color filter 1 While the light is transmitted twice, the reflective display has two values when the ambient light is incident and when it is reflected.
Once through the color filter. When the colored layers in the transmissive area and the reflective area are the same because the number of times of transmission through the color filter is different between transmissive display and reflective display,
The displayed color intensity, that is, the color purity is greatly different.
Also, in transmissive display, while the light source is backlight light,
In the reflective display, since the light source is natural light, not only the color purity but also the color tone changes.

As a method of making the display color of the transmissive region and the reflective region the same, it is conceivable to change the film thickness of the color material in the transmissive region and the reflective region. However, only by changing the film thickness of the color material, it is not possible to correct the change in color tone due to the light source in the transmissive display being backlight light and the light source in the reflective display being natural light.

As another method for making the display colors of the transmissive region and the reflective region the same, it is conceivable to separately paint the transmissive region and / or the reflective region with a plurality of color materials for all pixels. However, in the currently mainstream photolithography method, the color material is applied and formed six times or more,
The cost will increase.

As a method of enabling display with high color reproducibility in transmissive display and reflective display, a so-called pinhole method, which is a method of forming a transparent area in a reflective area to improve the brightness in reflective display, is special. It is described in Japanese Unexamined Patent Publication No. 2000-111902. In the color filter for a semi-transmissive liquid crystal display device having this configuration, although the photolithography process is performed three times, the color purity in the reflective display-the reflectance is higher than that in the above-described method of separately coating the transmissive area and / or the reflective area. There is a problem in that the characteristics are deteriorated, and it is not possible to achieve both at a level where the vividness of colors and sufficient brightness can be satisfied. In particular, when the color reproducibility in the transmissive display and the reflective display is increased, the brightness in the reflective display becomes dark and the performance as a liquid crystal display device becomes insufficient.

[0010]

SUMMARY OF THE INVENTION The present invention was devised in view of the above-mentioned drawbacks of the prior art, and reduces the chromaticity difference between the reflective mode and the transmissive mode for a semi-transmissive liquid crystal display device and reduces the color difference. An object of the present invention is to provide a color filter for a transflective liquid crystal display device having excellent characteristics and a good white balance and a transflective liquid crystal display device at low cost.

[0011]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve the problems of the prior art, the inventors of the present invention reduce the chromaticity difference between the reflection mode and the transmission mode with the following configuration, Moreover, they have found that it is possible to manufacture a color filter and a semi-transmissive liquid crystal display device that realize reflective display with excellent white balance at low cost. Further, since the blue pixel is composed of two or more kinds of colored layers, the white balance in the reflective display can be improved, and the effect is remarkable especially in the region where the color reproduction range in the transmissive display is high. I found it. It was also found that the effect of improving white balance in reflective display is remarkable by combining with a liquid crystal display device equipped with a three-wavelength type LED light source. That is, the present invention has the following constitution in order to solve the above problems. (1) At least one color pixel among red, blue, and green pixels is a color filter including a transmissive region and a reflective region, and the blue pixel is composed of two or more kinds of colored layers Color filter for liquid crystal display devices. (2) The color filter for a liquid crystal display device according to (1), wherein in at least one color pixel, the transmissive region and the reflective region are formed of the same colored layer, and the reflective region includes a transparent region. (3) A pixel having a chromaticity difference δ between the chromaticity (x0, y0) of the transmissive area and the chromaticity (x, y) of the reflective area does not include a pixel satisfying the following colors (1), The color filter for liquid crystal display device according to (2).

Δ = (x−x0) ² + (y−y0) ² ≧ 1 × 10 ⁻³ (4) A liquid crystal using the color filter described in any one of (1) to (3) above. Display device. (5) The liquid crystal display device according to (4), which comprises a three-wavelength LED light source as a backlight light source.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the liquid crystal display device of the present invention, the substrate on which the reflective film is formed may be a color filter side substrate or a substrate facing the color filter. When the reflective film is formed on the color filter side, the area where the reflective film is formed becomes the reflective area in the pixel area where the colored layer is formed, and the reflective film is formed in the pixel area. The non-open area is the transparent area. When the reflection film is formed on the substrate facing the color filter, the color filter pixel region corresponding to the reflection film formation region of the substrate becomes the reflection region, and the color filter pixel region is formed on the region of the substrate where the reflection film is not formed. The corresponding color filter pixel area becomes the transmission area.

In the color filter of the present invention, the blue pixel is composed of two or more kinds of colored layers, and the reflective area of the pixel is composed of the colored area and the transparent area for at least one color. The transparent region here is specifically a region having an average transmittance of 80% or more in the visible region. The two or more kinds of colored layers refer to pigments, materials forming pixels including a polymer, and coloring layers having different composition ratios of the materials.

By including a transparent region in the reflective region for pixels of at least one color, it is possible to improve the white balance in reflective display even with the same colored layer having the same film thickness. If the color in which the transparent region exists is at least one color, the difference between the transmissive display and the reflective display is further reduced and the number of steps is also reduced, so that the effect of the present invention is exerted. Further, by forming the blue pixel with two or more kinds of colored layers, it is possible to further reduce the chromaticity difference between the transmissive mode and the reflective mode and further improve the white balance in the reflective display. The method of forming two or more types of colored layers in the green pixel is not particularly limited, and two or more types of colored layers may be arranged in a plane, or two or more types of colored layers may be laminated in the transmission region. .

Regarding the chromaticity difference δ between the chromaticity (x0, y0) of the transmissive area and the chromaticity (x, y) of the reflective area, δ = (x
It is preferable not to include a pixel satisfying −x0) ² + (y−y0) ² ≧ 1 × 10 ⁻³ .

The transmission region chromaticity referred to here is obtained from the spectral spectrum obtained when the above-mentioned color filter transmission region is measured with a microspectrophotometer or the like. The reflection area chromaticity is obtained by squaring the spectral spectrum of the colored area and the spectral spectrum of the transparent area in each area at each wavelength, and taking the weighted average of the areas of the colored area and the transparent area. .

In the calculation of chromaticity, in order to take into consideration the difference of light sources, the transmission area is selected from the C light source, the two-wavelength type light source and the three-wavelength type light source, and the reflection area is the D65 light source. It is preferable. An example of the two-wavelength type LED light source mentioned here is an LED light source that emits white light by combining a blue LED and a yellow phosphor or a yellow-green phosphor. Examples of the three-wavelength type light source include a three-wavelength fluorescent tube, a white LED light source combining an ultraviolet LED and red, blue, and green phosphors, a white LED light source combining red, blue, and green LEDs, and an organic material. Examples include electroluminescent light sources.

In the color filter of the present invention, for a pixel including a transparent region, the ratio of the area of the transparent region to the total area of the reflective region (hereinafter referred to as "transparent region ratio") is important. When there are a plurality of color pixels including a transparent area, it is preferable that the transparent area ratio be large in the order of green> red≈blue. Specifically, the transparent area ratio is 15% or more and 35% or less for green pixels, and 5% for red pixels.
20% or less, and preferably 20% or less for blue pixels. Furthermore, regarding the green pixel,
The transparent area ratio is 20% or more and 30% or less, 8% or more and 16% or less for red pixels, and 5% for blue pixels.
% Or more and 16% or less is more preferable.

If the transparent area ratio deviates from the above range in the direction of narrowness, a bright display cannot be obtained in the reflective display, and
If the transparent area ratio deviates in a wide direction, it is not possible to obtain a vivid display during reflective display.

The formation of the color filter is not limited to the transparent substrate side such as glass or polymer film, but can be performed on the driving element side substrate. The pattern shape of the color filter may be stripe shape, island shape, or the like, but is not particularly limited. Further, a columnar fixed spacer may be arranged on the color filter, if necessary.

The color filter of the present invention is composed of at least three color pixels of red, green and blue, and the coloring material to be used may be an organic pigment, an inorganic pigment or a dye in general. it can. Examples of typical pigments include Pigment Red (PR-), 2, 3, 22, 38, 4
8: 1, 122, 149, 166, 168, 177, 2
02, 206, 207, 209, 224, 242, 25
4, Pigment Orange (PO-) 5, 13, 17, 3
1, 36, 38, 40, 42, 43, 51, 55, 5
9, 61, 64, 65, 71, Pigment Yellow (P
Y-) 12, 13, 14, 17, 20, 24, 83, 8
6, 93, 94, 109, 110, 117, 125, 1
37, 138, 139, 147, 148, 150, 15
3, 154, 166, 173, 185, Pigment Blue (PB-) 15 (15: 1, 15: 2, 15: 3, 1
5: 4, 15: 6), 21, 22, 60, 64, Pigment Violet (PV-) 19, 23, 29, 32,
33, 36, 37, 38, 40, 50 and the like. In the present invention, various pigments can be used without being limited thereto.

The above-mentioned pigments may be subjected to surface treatment such as rosin treatment, acidic group treatment, basic treatment and pigment derivative treatment, if necessary. PR (Pigment Red), PY (Pigment Yellow), PV
(Pigment Violet), PO (Pigment Orange), etc. are color index (CI; The Societ
y of Dyers and Colorists, Inc.), officially with the C.I. I. With a suffix (for example, CIP
R254). This defines a dye or a standard for dyeing, and each symbol also designates a specific standard dye and its color. In the following description of the present invention, in principle, the above C. I. Is omitted (for example, if CIPR254, PR25
4) Do.

However, in the colorant for red pixels of the color filter of the present invention, PR48: 1, PR12
2, PR202, PR206, PR207, PR20
9, PR242, PR254, PO38, PY17, P
It is more preferable to use Y138, PY150, PV19.

In the colorant for the green pixel of the color filter of the present invention, PG7, PG36, PY17, PY13
8, it is more preferable to use PY150. Also,
As a colorant for blue pixels, PB15 (15: 1, 15:
2, 15: 3, 15: 4, 15: 6), 60, PV1
It is more preferable to use 9,23.

Since the flatness of the surface may be impaired by forming the transparent region, it is preferable to form an overcoat layer as a flattening layer on the colored layer. Specifically, epoxy film, acrylic epoxy film, acrylic film,
Examples thereof include a siloxane polymer film, a polyimide film, a silicon-containing polyimide film, and a polyimide siloxane film.

The method of forming the pixel may be a photolithography method, a printing method, an electrodeposition method or the like, but is not particularly limited. Considering the pattern formability and the like, the photolithography method is more preferable.

The color filter of the present invention is used in combination with a semi-transmissive liquid crystal display device. Here, the semi-transmissive liquid crystal display device is a liquid crystal display device having a reflective film made of an aluminum film, a silver film or the like and having a slit. The color filter of the present invention is not limited to the driving method and display method of a liquid crystal display device, and is applied to various liquid crystal display devices such as an active matrix method, a passive matrix method, a TN mode, an STN mode, an ECB mode, and an OCB mode. It Further, the liquid crystal display device can be used without being limited to the configuration of the liquid crystal display device, such as the number of polarizing plates and the position of the scatterer.

It is important that the backlight light source used in the present invention is a three-wavelength type light source, and there are no side peaks that are impure components other than the peaks corresponding to red, green and red. Or it is important that it is small and the spectrum shape is steep. As long as the light source satisfies the above conditions, cold cathode fluorescent tubes, hot cathode fluorescent tubes, light emitting diodes (LEDs), organic electroluminescent light sources, inorganic electroluminescent light sources, flat fluorescent lamps, metal halide lamps and other general light sources can be used. However, if it is a three-wavelength type LED light source, in order to obtain high color reproducibility in transmissive display and excellent characteristics (color reproducibility, brightness, white balance) in reflective display, which is an object of the present invention. It was found that it has a remarkable effect on the above.

The three-wavelength type LED light source includes a white light source in which diodes each of which emits each color of RGB are combined, and a white light source in which an ultraviolet light emitting diode and a phosphor corresponding to each of RGB colors are combined. As an example, Sharp Corporation's chip LED "GM1WA80350"
A ”,“ GM4WA10350A ”, etc. are mentioned. As a white LED light source combining an ultraviolet light emitting diode and a phosphor corresponding to each of RGB colors, a white LED manufactured by Toyoda Gosei Co., Ltd.
(Nikkei Electronics, 2-25, 2002)
issue).

An example of the color filter manufacturing method of the present invention will be described. A color paste containing at least a polyimide precursor, a colorant, and a solvent is applied on a transparent substrate, and then a polyimide precursor colored film is formed by air drying, heat drying, vacuum drying, or the like. In the case of heat drying, it is preferable to use an oven, a hot plate or the like, and to perform the heating in the range of 50 to 180 ° C. for 1 minute to 3 hours. Next, a pattern is formed on the thus obtained polyimide precursor colored film by ordinary wet etching. First, a positive photoresist is applied on the polyimide precursor colored coating to form a photoresist coating. Subsequently, a mask is placed on the photoresist film, and ultraviolet rays are irradiated using an exposure device.
After the exposure, the photoresist coating and the polyimide precursor colored coating are simultaneously etched with a positive photoresist alkaline developer. After etching, the photoresist film that is no longer needed is removed.

The polyimide precursor colored film is then converted into a polyimide colored film by heat treatment. The heat treatment is usually performed in air, in a nitrogen atmosphere, or in a vacuum at 150 to 350 ° C., preferably 18 ° C.
It is carried out continuously or stepwise at a temperature of 0 to 250 ° C. for 0.5 to 5 hours. A color filter for a liquid crystal display device can be produced by performing the above steps on a red, green, and blue color paste and, if necessary, a black color paste.

Next, an example of a liquid crystal display device produced by using this color filter will be described. A transparent protective film is formed on the color filter, and I is further formed on the transparent protective film.
A transparent electrode such as a TO film is formed. Next, this color filter substrate and a reflective electrode substrate on which a reflective electrode such as a metal vapor deposition film is formed, and a liquid crystal alignment film that has been subjected to a rubbing treatment for liquid crystal alignment provided on those substrates,
And via a spacer for maintaining the cell gap,
Face and stick together. In addition, on the reflective electrode substrate,
In addition to the reflection electrode, a projection for light diffusion, a thin film transistor (TFT) element or a thin film diode (TFD) element, a scanning line, a signal line, and the like are provided, and a TFT liquid crystal display device,
A TFD liquid crystal display device can be created. Next, after injecting liquid crystal from the injection port provided in the seal part, the injection port is sealed. Next, the module is completed by mounting an IC driver or the like.

Next, an example of a method of manufacturing the backlight light source used in the present invention will be described.

In a backlight light source using LEDs, LED elements are arranged on a substrate on which wiring is patterned so as to apply a required voltage, a driver IC for driving is attached, a diffusion plate, a light guide plate, a prism sheet, A backlight light source is completed by appropriately combining guide lots and the like.

[0036]

[Example] <Measurement method> Transmittance, color coordinates: Otsuka Electronics Co., Ltd.
Using an "MCPD-2000" microspectrophotometer manufactured by Mfg. Co., Ltd., it was measured using a glass on which ITO was formed under the same film forming conditions as the film formed on the color filter as a reference.

The transmission region chromaticity referred to here is obtained from the spectral spectrum obtained when the above-mentioned color filter transmission region is measured with a microspectrophotometer or the like. The reflection area chromaticity is obtained by squaring the spectral spectrum of the colored area and the spectral spectrum of the transparent area in each area at each wavelength, and taking the weighted average of the areas of the colored area and the transparent area. .

Next, the present invention will be described using examples and comparative examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, the ratio of the reflection plate forming region (reflection region) to the pixel opening having a degree of freedom in design is 50% unless otherwise specified. The area where the transparent resin layer is formed is the reflective area of each pixel.

Example 1 A. Preparation of Polyamic Acid Solution 95.1 g of 4,4′-diaminodiphenyl ether and 6.2 g of bis (3-aminopropyl) tetramethyldisiloxane were charged together with 525 g of γ-butyrolactone and 220 g of N-methyl-2-pyrrolidone,
After adding 144.1 g of 3 ', 4,4'-biphenyltetracarboxylic dianhydride and reacting at 70 ° C for 3 hours, 3.0 g of phthalic anhydride was added and further reacting at 70 ° C for 2 hours. , 25% by weight polyamic acid solution (P
AA) was obtained.

B. Synthesis of polymer dispersant 4,4'-diaminobenzanilide 161.3 g,
3,3'-diaminodiphenyl sulfone 176.7
g, and 18.6 g of bis (3-aminopropyl) tetramethyldisiloxane with γ-butyrolactone 2667
g, N-methyl-2-pyrrolidone (527 g), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (439.1 g) was added, and the mixture was reacted at 70 ° C. for 3 hours, and then phthalic anhydride was added. 2.2g was added, and 70 more
The reaction was carried out at 0 ° C. for 2 hours to obtain a polymer dispersant (PD) which was a 20% by weight polyamic acid solution.

C. Preparation of Dispersion Pigment Red PR209, 2.7 g (60 wt
%), Pigment Red PR254, 1.8 g (40 w
t%) and 22.5 g of polymer dispersant (PD) and γ
-Butyrolactone 42.8 g, 3-methoxy-3-methyl-1-butanol 20.2 g and glass beads 90
Charge with g and use homogenizer for 7,000 r
After dispersing at pm for 5 hours, the glass beads were filtered off. In this way, a 5% dispersion liquid (RD) of PR209 and PR254 was obtained.

D. Preparation of color paste To 50.0 g of dispersion liquid (RD), polyamic acid solution (P
AA) 8.0 g of a solution obtained by diluting 70.0 g of γ-butyrolactone was added and mixed, and a red color paste (R-
1) was obtained. Similarly, in the proportions shown in Table 1, the red paste (R-2 to R-4), the green paste (G-1 to G-4),
Blue pastes (B-1 to B-4) were obtained.

[0043]

[Table 1]

E. Preparation and Evaluation of Colored Coating Film The red paste (R-1) was applied onto a glass substrate on which a black matrix had been patterned by a spinner and dried at 120 ° C. for 20 minutes. A positive photoresist (OFPR-800 made by Tokyo Ohka Co., Ltd.) on top of this
Was applied and dried at 90 ° C. for 10 minutes. Using a UV exposure device PLA-501F manufactured by Canon Inc., exposure was performed at 60 mJ / cm ² (UV intensity of 365 nm) through a photomask made of chromium. The photomask used at this time has a transparent region ratio (transparent region ratio) of 9% in the reflective region. After the exposure, the photoresist was immersed in a developer containing a 2.25% aqueous solution of tetramethylammonium hydroxide to develop the photoresist and etch the colored film of the polyimide precursor at the same time. The photoresist layer that became unnecessary after etching was removed with acetone. Furthermore, the colored coating film of the polyimide precursor was heat-treated at 240 ° C. for 30 minutes to be converted into polyimide. The coating thickness after heat treatment is 1.
The chromaticity (x, y) when passing through a C light source at 1 μm was (0.490, 0.284). Next, the green paste (G-1) was applied and photolithography was performed in the same manner as the red pixel. In the photomask used at this time, the ratio of the transparent area in the reflective area (transparent area ratio) is 23%. The film thickness of the green pixel after heat treatment is 1.1 μm, and the chromaticity (x, y) when passing through a C light source is (0.293, 0.45).
6). Next, use a spinner to color paste (B-
1) was applied and photolithography was performed in the same manner as the red pixel to form a colored layer in the transmission region. The thickness of the blue colored layer is 1.
The chromaticity of the finished product (x,
y) was (0.160, 0.202). Finally, the color paste (B-2) was applied with a spinner and subjected to photolithography to form a colored layer in the reflection area of the blue pixel.
Chromaticity (x, when passing a C light source in the reflection area of the blue pixel)
y) is (0.210, 0.243) and the film thickness is 1.1 μ.
It was m. An overcoat layer having a thickness of 2 μm is formed on the pixel film thus obtained, and I is further formed thereon.
The TO film was sputtered to a film thickness of 0.1 μm. A schematic cross-sectional view of the manufactured color filter is shown in FIG.
Shown in. D6 of the color filter thus obtained
Table 2 shows the chromaticity of the reflection area with five light sources, the chromaticity of the transmission area with two wavelength type LED light sources, and the chromaticity difference δ.

[0045]

[Table 2]

Comparative Example 1 A color mask (B-1) was applied with a spinner so that the film thickness after heat treatment would be 1.1 μm, and a photomask having a transparent area ratio of 11% in the reflective area was used. A color filter was produced in the same manner as in Example 1 except that the color paste (B-2) was not applied.
At this time, the chromaticity (x, y) when the transmission area of the blue pixel was measured with the C light source was (0.160, 0.202). Table 3 shows the chromaticity in the reflection area of the D65 light source, the chromaticity in the transmission area of the two-wavelength LED light source, and the chromaticity difference δ of the color filter thus obtained.

[0047]

[Table 3]

Comparative Example 2 Red pixels and blue pixels were processed in the same manner as in Comparative Example 1,
For green pixels, use spinner to color paste (G-
1) was applied and photolithography was performed to form a colored layer in the transmission region. The green pixel thickness at this time is 1.1 μm, and the chromaticity (x, y) when passing through a C light source is (0.293, 0.4).
56). Further, the color paste (G-2) was applied with a spinner and subjected to photolithography to form a green colored layer in the reflection area of the green pixel. The film thickness of the reflection area of the green pixel is 1.1 μm, and the chromaticity (x,
y) was (0.316, 0.383). Table 4 shows the chromaticity in the reflection area of the D65 light source, the chromaticity in the transmission area of the two-wavelength LED light source, and the chromaticity difference δ of the color filter thus obtained.

[0049]

[Table 4]

Comparative Example 3 Green and blue pixels were processed in the same manner as in Comparative Example 1,
For red pixels, use a spinner to color paste (R-
1) was applied and photolithography was performed to form a colored layer in the transmission region. At this time, the film thickness of the red pixel transmitting region is 1.1.
The chromaticity (x, y) at the time of passing through the C light source is (0.
490, 0.284). Moreover, the color paste (R-2) is applied with a spinner, and photolithography is performed.
A red colored layer was formed in the reflective area of the red pixel. The film thickness of the reflection area of the red pixel was 1.1 μm, and the chromaticity (x, y) when passing through the C light source was (0.427, 0.290). Table 5 shows the chromaticity in the reflection area of the D65 light source, the chromaticity in the transmission area of the two-wavelength LED light source, and the chromaticity difference δ of the color filter thus obtained.

[0051]

[Table 5]

The difference in display characteristics between the semi-transmissive liquid crystal display device using the color filters manufactured in Comparative Examples 1, 2 and 3 and the liquid crystal display device using the color filter of Example 1 is transmissively displayed. In a dark room, and in a reflective display under an outdoor environment light. A two-wavelength LED light source was used as the light source used in the transmission mode. The liquid crystal display device using the color filter of Example 1 had almost no difference in hue between the reflective mode and the transmissive mode, and the brightness in reflective display was the same as that of Comparative Example 1. This is because the difference between the chromaticity of the reflection area chromaticity and the chromaticity of the transmission area of the color filter of Example 1 is small, and the white reflection area luminance is Comparative Example 1.
It is supposed to be equivalent to. The liquid crystal display device using the color filter of Example 1 showed good display characteristics without coloring in white display. This is presumably because the whiteness of the reflection area of the color filter of Example 1 was smaller than that of the reflection area of Comparative Example 1 in both x and y, and was bluish white. Although Comparative Examples 2 and 3 were slightly brighter than Example 1, they were colored yellow when displaying white and the display quality was poor. It is presumed that this is because the reflection area whiteness of the color filters of Comparative Examples 2 and 3 is larger in both x and y than the reflection area whiteness of Example 1, and is yellowish white. It

Example 2 A red paste (R-3) was applied onto a glass substrate on which a black matrix was patterned by a spinner. The coating film was dried at 120 ° C. for 20 minutes, and a positive photoresist (“OFP” manufactured by Tokyo Ohka Co., Ltd.
R-800 ″) was applied and dried at 90 ° C. for 10 minutes. 60 mJ / cm ² using a Canon photomask “PLA-501F” through a chrome photomask.
(UV intensity of 365 nm) It was exposed. The photomask used at this time has a ratio of the transparent area in the reflective area (transparent area ratio) of 11%. After the exposure, it was immersed in a developing solution composed of a 2.0% aqueous solution of tetramethylammonium hydroxide to develop the photoresist and etch the colored coating film of the polyimide precursor at the same time.
The photoresist layer that became unnecessary after etching was removed with acetone. Furthermore, a colored coating film of the polyimide precursor is applied 24
It was heat-treated at 0 ° C. for 30 minutes and converted into polyimide. The thickness of the coating film after heat treatment is 1.8 μm, and the chromaticity (x, y) when passing through a C light source in the transmission region is (0.622, 0.32).
8).

Next, color paste (G-
3) was applied and photolithography was performed in the same manner as for the red pixel except that a photomask having a transparent area ratio of 26% in the reflective area was used to form a colored layer. Green pixel film thickness is 1.8μ
The chromaticity (x, y) when passing a C light source at m is (0.29
8, 0.581).

Next, the blue pixel was coated with a color paste (B-3) with a spinner and subjected to photolithography to form a colored layer in the transmission region. The blue pixel film thickness at this time is 1.8.
The chromaticity (x, y) at the time of passing through the C light source is (0.
136, 0.099). In addition, the color paste (B-4) is applied with a spinner, and photolithography is performed.
A blue colored layer was formed in the reflective area of the blue pixel. The thickness of the reflective region of the blue pixel was 1.8 μm, and the chromaticity (x, y) when passing through the C light source was (0.210, 0.243).

An overcoat layer ("Optomer SS6500 / S" manufactured by JSR Corporation) was formed on the pixel film thus obtained.
S0500 ″) was formed into a film with a thickness of 2 μm.
The TO film was sputtered to a film thickness of 0.1 μm. With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at the corners of each substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. Table 6 shows the chromaticity of the reflection area in the D65 light source and the chromaticity of the transmission area in the two-wavelength LED light source.

[0057]

[Table 6]

Comparative Example 4 A color mask (B-3) was applied by a spinner so that the film thickness after heat treatment was 1.8 μm, and a photomask having a transparent area ratio of 18% in the reflection area was prepared. A color filter was produced in the same manner as in Example 2 except that the color paste (B-4) was not used. At this time, the chromaticity (x, y) when the C pixel light source was passed through the transmission area of the blue pixel was (0.136, 0.099). With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at each corner of the substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. D65 light source reflection area chromaticity, dual wavelength type LED
Table 7 shows the chromaticity of the transmissive region with the light source.

[0059]

[Table 7]

Comparative Example 5 Red pixels and blue pixels were processed in the same manner as in Comparative Example 4,
For green pixels, apply color paste (G-3),
Photolithography was performed to form a colored layer in the transmission area. The green pixel film thickness at this time was 1.8 μm, and the chromaticity (x, y) when passing through a C light source was (0.298, 0.581). Finally, a color paste (G-4) was applied with a spinner and subjected to photolithography to form a green colored layer in the reflection area of the green pixel. When the C light source was passed through the reflection area of the green pixel, the chromaticity (x, y) was (0.316, 0.383) and the film thickness was 1.8 μm.

With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at each corner of the substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. Table 8 shows the chromaticity of the reflection area in the D65 light source and the chromaticity of the transmission area in the two-wavelength LED light source.

[0062]

[Table 8]

Comparative Example 6 The green and blue pixels were processed in the same manner as in Comparative Example 4,
For red pixels, apply color paste (R-3),
Photolithography was performed to form a colored layer in the transmission area. At this time, the red pixel film thickness was 1.8 μm, and the chromaticity (x, y) when passing through the C light source was (0.622, 0.328). In addition, a color paste (R-4) was applied with a spinner and subjected to photolithography to form a red colored layer in the reflection area of the red pixel. The thickness of the reflective area of the red pixel is 1.8μ
The chromaticity (x, y) when passing a C light source at m is (0.4
27, 0.290). With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at each corner of the substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. Table 9 shows the chromaticity of the reflection area in the D65 light source and the chromaticity of the transmission area in the two-wavelength LED light source.

[0064]

[Table 9]

The difference in display characteristics between the semi-transmissive liquid crystal display device using the color filters produced in Comparative Examples 4 to 6 and the liquid crystal display device using the color filter of Example 2 was the same. The display was compared under outdoor ambient light. The light source used for the transmission mode is 2
A wavelength type LED light source was used. The liquid crystal display device using the color filter of Example 2 showed good display characteristics without coloring in white display. This is presumed to be because the reflection area whiteness of the color filter of Example 2 was smaller in both x and y than the reflection area whiteness of Comparative Example 4, and was bluish white. For Comparative Example 5 and Comparative Example 6,
Although slightly brighter than in Example 1, it was colored yellow when displaying white, and the display quality was poor. This is because the whiteness of the reflective areas of the color filters of Comparative Example 5 and Comparative Example 6 is Example 2.
It is presumed that this is because both x and y are larger than the whiteness of the reflection area and the whiteness is yellowish.

When the color reproducibility of the transmissive display is 60% compared to the effect of improving the white balance of the reflective display when the color reproducibility of the transmissive display is 22% (Example 1, Comparative Examples 1 to 3) ( It was found that the effect of improving the white balance of Example 2 and Comparative Examples 4 to 6) was large, and the effect of the present invention was particularly high in a region having a high color reproduction range.

Example 3 A red paste (R-3) was applied onto a glass substrate on which a black matrix was patterned by a spinner. The coating film was dried at 120 ° C. for 20 minutes, and a positive photoresist (“OFP” manufactured by Tokyo Ohka Co., Ltd.
R-800 ″) was applied and dried at 90 ° C. for 10 minutes. 60 mJ / cm ² using a photomask made of chrome using an ultraviolet exposure device “PLA-501F” made by Canon Inc.
(UV intensity of 365 nm) It was exposed. The photomask used at this time has a ratio of the transparent area in the reflective area (transparent area ratio) of 11%. After the exposure, it was immersed in a developing solution composed of a 2.0% aqueous solution of tetramethylammonium hydroxide to develop the photoresist and etch the colored coating film of the polyimide precursor at the same time.
The photoresist layer that became unnecessary after etching was removed with acetone. Furthermore, a colored coating film of the polyimide precursor is applied 24
It was heat-treated at 0 ° C. for 30 minutes and converted into polyimide. The thickness of the coating film after heat treatment was 1.2 μm, and the chromaticity (x, y) when passing through a C light source in the transmission region was (0.567, 0.31).
It was 0).

Next, the color paste (G-3) was applied to the green pixels by a spinner, and photolithography was performed in the same manner as the red pixels except that a photomask having a transparent area ratio of 27% in the reflective area was used. A colored layer was formed. The thickness of the green colored layer is 1.2 μm, and the chromaticity (x, y) when passing through the C light source through the transmissive region is (0.321, 0.54).
It was 1).

Next, the color paste (B-3) was applied and subjected to photolithography to form a colored layer in the transmission region. At this time, the blue pixel film thickness was 1.2 μm, and the chromaticity (x, y) when passing through the C light source was (0.138, 0.127). Further, the color paste (B-2) was applied with a spinner and subjected to photolithography to form a blue colored layer in the reflection area of the blue pixel. The thickness of the blue pixel reflection area is 1.1μ.
The chromaticity (x, y) when passing through a C light source at m is (0.2
10, 0.243).

An overcoat layer ("Optomer SS6500 / S" manufactured by JSR Corporation) was formed on the pixel film thus obtained.
S0500 ″) was formed into a film with a thickness of 2 μm.
The TO film was sputtered to a film thickness of 0.1 μm. With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at the corners of each substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. Shows the chromaticity of the reflection area in the D65 light source, the chromaticity of the transmission area in the three-wavelength type LED that combines the UV LED and the red-green-blue phosphor, and the chromaticity of the transmission area in the three-wavelength type LED that combines the RGB colors. Shown in 10.

[0071]

[Table 10]

Comparative Example 7 A color mask (B-3) was applied by a spinner so that the film thickness after heat treatment was 1.2 μm, and a photomask having a transparent area ratio of 20% in the reflective area was prepared. A color filter was produced in the same manner as in Example 3 except that the color paste (B-2) was not used. At this time, the chromaticity (x, y) when the C pixel light source was passed through the transmission area of the blue pixel was (0.138, 0.127). With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at each corner of the substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. Shows the chromaticity of the reflection area in the D65 light source, the chromaticity of the transmission area in the three-wavelength type LED that combines the UV LED and the red-green-blue phosphor, and the chromaticity of the transmission area in the three-wavelength type LED that combines the RGB colors. 11 shows.

[0073]

[Table 11]

Comparative Example 8 Red pixels and blue pixels were processed in the same manner as in Comparative Example 7,
For green pixels, use spinner to color paste (G-
3) was applied and photolithography was performed to form a colored layer in the transmission region. The green pixel thickness at this time is 1.2 μm, and the chromaticity (x, y) when passing through a C light source is (0.321, 0.5).
41). Finally, a color paste (G-2) was applied with a spinner and subjected to photolithography to form a green colored layer in the reflection area of the green pixel. C in the reflection area of the green pixel
Chromaticity (x, y) when passing through a light source is (0.316,
0.383) and the film thickness was 1.1 μm. With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at each corner of the substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. D65
Table 12 shows the chromaticity of the reflection area in the light source, the chromaticity of the transmission area in the three-wavelength type LED combining the UV LED and the red-green-blue phosphor, and the chromaticity of the transmission area in the three-wavelength type LED combining the LEDs of each color of RGB. Shown in.

[0075]

[Table 12]

Comparative Example 9 The green and blue pixels were processed in the same manner as in Comparative Example 7,
For red pixels, apply color paste (R-3),
Photolithography was performed to form a colored layer in the transmission area. At this time, the red pixel film thickness was 1.2 μm, and the chromaticity (x, y) when passing through the C light source was (0.567, 0.310). In addition, a color paste (R-2) was applied with a spinner and subjected to photolithography to form a red colored layer in the reflection area of the red pixel. The thickness of the reflective area of the red pixel is 1.1μ
The chromaticity (x, y) when passing a C light source at m is (0.4
27, 0.290). With respect to the color filter substrate thus obtained, the spectrum was measured for one pixel at the center of the substrate and four pixels at each corner of the substrate. The measured pixel spectra were averaged for each measurement part to obtain chromaticity. Shows the chromaticity of the reflection area in the D65 light source, the chromaticity of the transmission area in the three-wavelength type LED that combines the UV LED and the red-green-blue phosphor, and the chromaticity of the transmission area in the three-wavelength type LED that combines the RGB colors. 13 shows.

[0077]

[Table 13]

The difference in display characteristics between the semi-transmissive liquid crystal display device using the color filters produced in Comparative Examples 7 to 9 and the liquid crystal display device using the color filter of Example 3 was the same. The display was compared under outdoor ambient light. The light source used for the transmission mode is a three-wavelength LE that combines an ultraviolet LED and a red-green-blue phosphor.
Three-wavelength type LED (manufactured by Sharp Corp.) "D4 (manufactured by Toyoda Gosei Co., Ltd.)"
10350A ″) was used. The liquid crystal display device using the color filter of Example 3 showed good display characteristics without coloring in white display. This is because the whiteness of the reflection area of the color filter of Example 3 was Compared with the reflection area whiteness of Comparative Example 7,
It is presumed that this is because both x and y are small and the color is bluish white. Comparative Examples 8 and 9 were slightly brighter than Example 1, but were colored yellow when displaying white, and the display quality was poor. This is Comparative Examples 8 and 9.
It is presumed that this is because the reflection area whiteness of the color filter of No. 2 is larger in x and y than the reflection area whiteness of Example 2 and is yellowish white.

When the color reproducibility of the transmissive display is 60%, compared with the white balance improving effect of the reflective display when the color reproducibility of the transmissive display is 22% (Example 1, Comparative Examples 1 to 3) ( It was found that the white balance improving effect of Example 3 and Comparative Examples 7 to 9) was large, and the effect of the present invention was particularly high in a region having a high color reproduction range. Further, compared with Example 2 using the two-wavelength type LED light source, Example 3 using the three-wavelength type LED light source is very bright, and the combination with the three-wavelength type LED light source is particularly improved in brightness. It turns out that the effect is high.

[0080]

Since the present invention is constructed as described above, it is a color for a semi-transmissive liquid crystal display device which has a small chromaticity difference between the reflective mode and the transmissive mode, has an excellent white balance, and enables bright reflective display. A filter and a transflective liquid crystal display device can be obtained at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a color filter used in the present invention.

FIG. 2 is a spectrum example of a three-wavelength light source used in the present invention (ultraviolet LED + red-green-blue phosphor).

FIG. 3 is a spectrum example of a three-wavelength light source used in the present invention (a combination of red, green, and blue LEDs).

FIG. 4 is a spectrum example of a conventional dual-wavelength LED light source.

[Explanation of symbols]

1: Transparent substrate 2: Black matrix 3: Colored layer 4: Reflection area 5: Transmission area 6B: Blue pixel area 6G: green pixel area 6R: Red pixel area 7: Transparent area 8: Overcoat layer

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H048 BA02 BA11 BA45 BA48 BB02                       BB07 BB37 BB42                 2H091 FA02Y FA45 FB13 FC10                       FC26 FC29 FC30 FD04 FD13                       FD24 KA10 LA03 LA11 LA12                       LA15

Claims (5)

[Claims] 1. A color filter in which at least one color pixel among red, green, and blue pixels includes a transmissive region and a reflective region, and the blue pixel is composed of two or more kinds of colored layers. Liquid crystal display color filter. 2. The color for a liquid crystal display device according to claim 1, wherein, in at least one color pixel, the transmissive region and the reflective region are formed of the same colored layer, and the reflective region includes a transparent region. filter. 3. A pixel having a chromaticity difference δ between the chromaticity (x0, y0) of the transmissive area and the chromaticity (x, y) of the reflective area does not include a pixel satisfying the following colors. The color filter for liquid crystal display device according to any one of 1 and 2. δ = (x−x0) ² + (y−y0) ² ≧ 1 × 10 ⁻³ 4. A liquid crystal display device using the color filter according to claim 1. 5. A three-wavelength type L as a backlight light source.
The liquid crystal display device according to claim 4, comprising an ED light source.