JP2004258413A - Semitransmission type liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device having high light utilizing efficiency so as to be effective to both a transmission mode and a reflection mode. <P>SOLUTION: A stripe-shaped transparent electrode group 3 is formed on a glass substrate 2, a stripe-shaped light reflecting metal layer is deposited on the transparent electrode group 3, a light transmission part is patterned, and an orientation layer 6 is formed. A structure formed by combining a color filter 7a wherein transparent fine particles are dispersed and a color filter 7b wherein the transparent fine particles are not dispersed is formed on a glass substrate 1, an over coating layer 8 and a stripe-shaped transparent electrode group 9 are further successively formed thereon, and an alignment layer 10 is further formed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transflective liquid crystal display for color display used in both a reflection mode and a transmission mode.
[0002]
[Prior art]
In recent years, liquid crystal display devices have been used for large and high-definition monitors in addition to small or medium-sized portable information terminals and notebook computers. Further, a technology of a reflective liquid crystal display device that does not use a backlight has been developed, and is excellent in thinness, light weight, and low power consumption.
[0003]
Reflection type liquid crystal display devices are of the scattering reflection type, in which a light reflection layer with an uneven shape is formed on the inner surface of the substrate disposed behind, but the surrounding light can be used effectively by using no backlight. ing.
[0004]
In addition, a transflective liquid crystal display device has been developed in which a transflective film is formed instead of the light reflecting layer, a backlight is provided, and the transflective mode is selectively used in a reflective mode or a transmissive mode.
[0005]
According to this transflective liquid crystal display device, it can be used as a reflective device by external illumination such as sunlight or a fluorescent lamp, or used as a transmissive device by attaching a backlight. A semi-permeable membrane is used in order to have the film (see Patent Document 1). Further, it has been proposed to use a semi-transmissive film for the same purpose in an active matrix type transflective liquid crystal display device (see Patent Document 2).
[0006]
In addition, when the semi-transmissive film of the half mirror is used, there is a problem that it is difficult to improve both the functions of the reflectance and the transmittance, and in order to solve this problem, a reflection hole having a light transmitting hole is provided. A transflective liquid crystal display device using a film instead of the transflective film has been proposed (see Patent Document 3).
[0007]
Further, in the above transflective liquid crystal display device, in the transmission mode, light passes through the color filter once, whereas in the reflection mode, light passes through the color filter twice, so that the transmission mode is lower than the reflection mode. The color purity was reduced. For this reason, the area used in the transmission mode and the reflection mode is spatially divided, and the color filter in the transmission mode is made thicker than the color filter in the reflection mode to improve the color purity in the transmission mode. An improved transflective liquid crystal display device has been proposed (see Patent Documents 4 and 5).
[0008]
[Patent Document 1]
JP-A-8-292413 [Patent Document 2]
JP-A-7-318929 [Patent Document 3]
Patent No. 2878231 [Patent Document 4]
JP 2000-298271 A [Patent Document 5]
JP 2001-166289 A
[Problems to be solved by the invention]
When a light transmission hole or the like is formed in a pixel as in Patent Document 3, the hole portion can be used only in the transmission mode, and the portion other than the hole can be used only in the reflection mode. Could not be used.
[0010]
Further, according to Patent Literature 4 and Patent Literature 5, since it is necessary to change the film thickness of each color filter, the problem of surface flatness and the like has not been solved to the extent that it is still satisfactory.
[0011]
Furthermore, in a transflective type liquid crystal display device, there is a technology in which a light scattering function is provided by using a light scattering layer on the outside of the panel. However, according to the device having such a configuration, the following problem occurs. There is.
[0012]
That is, by forming the light-scattering layer outside the liquid crystal display cell constituted by the portion sandwiched between the glass substrate 1 and the glass substrate 2, the external light beam mainly used in the reflection mode is used for the light-scattering material. Surface reflection occurs on the surface, which causes a decrease in light use efficiency and a decrease in contrast of a liquid crystal display.
[0013]
Accordingly, an object of the present invention is to provide a high-performance transflective liquid crystal display device having a structure that is effective for both the transmission mode and the reflection mode.
[0014]
It is another object of the present invention to provide a high-performance transflective liquid crystal display device having improved light use efficiency and contrast of a liquid crystal display.
[0015]
[Means for Solving the Problems]
The transflective liquid crystal display device of the present invention has a structure in which a laminate of a light reflection film and a transparent electrode is formed on a transparent substrate, and one member formed by coating an alignment layer, and a color including light scattering particles on the transparent substrate. The other member formed by sequentially laminating the filter, the transparent electrode, and the alignment film is attached via a nematic liquid crystal to both transparent electrodes so that pixels are arranged in a matrix, and the light reflection film is adhered to the other member. A light transmitting hole was formed in the outer peripheral portion of the pixel, another light reflecting film was provided in a portion on the transparent substrate of the other member corresponding to the outer peripheral portion of the pixel, and a light source was arranged on the outer surface side of one member. It is characterized by the following.
[0016]
Further, another transflective liquid crystal display device of the present invention is characterized in that a color filter containing no light-scattering particles is provided at a portion of the other member corresponding to the outer peripheral portion of the pixel.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings using an STN-type liquid crystal display device as an example.
FIG. 1 is a sectional view of a transflective liquid crystal display device A.
[0018]
According to the transflective liquid crystal display device A, reference numeral 1 denotes a common side glass substrate, and reference numeral 2 denotes a segment side glass substrate. First, the configuration of one member (segment side) will be described.
[0019]
A stripe-shaped transparent electrode group 3, which is the transparent electrode made of ITO, is formed on a glass substrate 2 in parallel. A plurality of light-reflection films, Cr film 4 and Al film 5, are formed on the transparent electrode group 3. A laminated striped light-reflective metal layer is deposited.
[0020]
As shown in FIG. 3, the striped light-reflective metal layer is formed by removing the Cr film 4 and the Al film 5 uniformly formed by sputtering by patterning the inter-pixel and light transmitting portions by a photolithography process. can get.
[0021]
According to FIG. 3, a plurality of stripe-shaped transparent electrode groups (segment electrodes) made of ITO arranged in parallel on a segment side glass substrate 2 (denoted as Glass in FIG. 3) are formed by photolithography. This step is conventionally well-known, and is shown as “resist coating”, “exposure and development”, “ITO etching”, and “resist removal” in FIG.
[0022]
Then, a Cr film (350 °) and an Al film (1000 °) are uniformly formed by sputtering, and the inter-pixel and light-transmitting portions are simultaneously patterned and removed by photolithography. Layers. These steps are shown as “Cr and Al film formation”, “resist coating”, “exposure and development”, “Al and Cr etching”, and “resist stripping” as shown in FIG.
[0023]
Note that the Cr film 4 is interposed in order to enhance the adhesion between the ITO layer and the Al film.
[0024]
As for the light-reflective metal layer provided with the light transmitting portion as described above, a laminated structure of a Cr layer and an Al layer is provided. Instead of this laminated structure, an Al alloy such as AlNd, an Ag metal, an Ag alloy, or the like is used. May be used.
[0025]
As described above, the slit-shaped light transmitting portion is patterned on the striped light-reflective metal layer by the photolithography process.
[0026]
Further, according to the light-reflective metal layer having the above-described structure, the stripe-shaped light-reflective metal layer formed by laminating the Cr film 4 and the Al film 5 is deposited on the stripe-shaped transparent electrode group 3 made of ITO. In addition, since the light transmitting portion is formed by removing the metal layer, the transparent electrode layer exists at the portion where the light transmitting portion is formed. Therefore, the entire combination of the stripe-shaped transparent electrode group 3 and the stripe-shaped light-reflective metal layers of the Cr film 4 and the Al film 5 fulfills the electrode function.
[0027]
Then, an alignment film 6 made of a polyimide resin rubbed in a certain direction is formed on the stripe-shaped transparent electrode group 3 and the light-reflective metal layer.
[0028]
The other member (common side) has a structure in which a color filter 7a in which transparent fine particles are dispersed and a normal color filter 7b (in which no transparent fine particles are dispersed) are combined on the glass substrate 1.
[0029]
The formation of these color filters is performed as follows.
First, the color filter 7a in which the transparent fine particles as the light scattering particles are dispersed is formed on the glass substrate 1.
[0030]
As such fine particles, for example, ceramic particles such as alumina, zirconia, silicon nitride, silicon carbide, titanium carbide, titanium nitride, and titanium oxide, or silica particles and resin particles can be used. The shape of the transparent fine particles may be various shapes such as a spherical shape, a football shape, a column shape, a needle shape, and the like, or may be irregular.
[0031]
As the transparent fine particles, particularly, spherical transparent fine particles (2 μm diameter, SiO ₂ resin) are suitable in terms of the dispersibility of the fine particles in the color filter resin and the light scattering property. Such light scattering fine particles are composed of a transparent material such as ceramic particles or resin particles such as alumina and titanium oxide ("Micropearl" manufactured by Sekisui Chemical Co., Ltd.), silica particles, and the like. In this case, it is preferable that the incident light entering the color filter 7a is refracted at the interface between the colored resin and the light scattering fine particles, thereby causing light scattering.
[0032]
For example, when the light scattering fine particles are made of silica, the colored resin may be made of an acrylic resin, a polyimide resin, or a silicone resin. In particular, the specific gravity of the acrylic resin is set to 1.02. When it is set to 1.16, it is good in that the surface flatness is improved.
[0033]
A color filter resin in which the transparent fine particles are uniformly dispersed is formed corresponding to R (red), G (green), and B (blue) using a conventionally known photolithography technique, and a color filter is formed. 7a.
[0034]
Such a color filter 7a is preferably formed so as to correspond to both the light transmitting portion and the light reflecting portion of the transflective liquid crystal display device A, and scatters the light reflected by the light reflecting film and incident on the color filter 7a. This is preferable in that a specular display is alleviated in the reflection mode.
[0035]
As described above, the light scattering function is provided by forming the color filter 7a in which the transparent fine particles are dispersed.
[0036]
Next, as a color filter 7b, a color filter resin in which the above-mentioned transparent fine particles are not dispersed is applied to R (red), G (green), and B (blue) by photolithography using a conventionally known technique. The color filter 7b is formed.
[0037]
Such a color filter 7b is formed in a portion corresponding to the light transmitting portion of the transflective liquid crystal display device A. However, the color tone of the liquid crystal display in the transmissive mode is reduced with only the color filter 7a. It is desirable in complementing.
[0038]
On the color filters 7a and 7b, an overcoat layer 8 made of an acrylic resin and a striped transparent electrode group 9 made of ITO arranged in parallel in a large number are sequentially formed. An alignment film 10 made of a polyimide resin rubbed in a certain direction is formed on the substrate 9.
[0039]
Next, the glass substrate 2 and the glass substrate 1 intersect (orthogonal to each other) via a liquid crystal layer 11 made of a chiral nematic liquid crystal twisted at an angle of, for example, 200 to 260 °. ) Are bonded by a seal member (not shown). Although not shown, a large number of spacers are arranged between the glass substrates 1 and 2 to keep the thickness of the liquid crystal layer 11 constant.
[0040]
Further, a first retardation plate 12 made of polycarbonate, a second retardation plate 13, and an iodine-based polarizing plate 14 are sequentially stacked outside the glass substrate 1, and a third retardation plate 15 made of polycarbonate is placed outside the glass substrate 2. And an iodine-based polarizing plate 16 are sequentially stacked. In these arrangements, the adhesive is applied by applying an adhesive made of an acrylic material.
[0041]
Then, a light source such as a backlight is arranged on the outer surface side of the one member.
[0042]
Thus, according to the transflective liquid crystal display device A of the present invention, the slit-shaped light transmitting portion is provided for the light reflective metal layer, so that the light transmitting portion does not operate in the transmission mode, and the light transmitting portion except for the light transmitting portion is formed. The region is in the reflection mode.
[0043]
(Comparative example)
Next, a transflective liquid crystal display device B of a comparative example will be described. FIG. 2 is a schematic sectional view of the device B. The same parts as those of the transflective liquid crystal display device A shown in FIG.
[0044]
According to the transflective liquid crystal display device B, a stripe-shaped transparent electrode group 3 made of ITO is formed on the glass substrate 2 in a large number in parallel, and a Cr film 4 and an Al film 5 are formed on the transparent electrode group 3. A laminated striped light-reflective metal layer is deposited.
[0045]
As described above, this striped light-reflective metal layer goes through the process shown in FIG. That is, the Cr film 4 and the Al film 5 uniformly formed by sputtering are obtained by patterning and removing the portions between pixels and the light transmitting portion by a photolithography process.
[0046]
Then, an alignment film 6 made of a polyimide resin rubbed in a certain direction is formed on the stripe-shaped transparent electrode group 3 and the light-reflective metal layer.
[0047]
On the other hand, on the glass substrate 1, a color filter 7, an overcoat layer 8 made of an acrylic resin, and a stripe-shaped transparent electrode group 9 made of ITO arranged in parallel in large numbers are sequentially formed. An alignment film 10 made of a polyimide resin rubbed in a certain direction is formed thereon.
[0048]
Further, both the striped transparent electrode groups 3 and 9 intersect (orthogonal) the glass substrate 2 and the glass substrate 1 via a liquid crystal layer 11 made of a chiral nematic liquid crystal twisted at an angle of 200 to 260 °. ) Are bonded by a seal member (not shown).
[0049]
Further, a light scattering layer 12 made of a light scattering material, a first retardation plate 13, a second retardation plate 14 made of polycarbonate, and an iodine-based polarizing plate 15 are sequentially stacked on the outside of the glass substrate 1. A third retardation plate 16 made of polycarbonate and an iodine-based polarizing plate 17 are sequentially stacked.
[0050]
According to such a transflective liquid crystal display device B, like the transflective liquid crystal display device A described above, the slit-shaped light transmissive portion is provided in the light reflective metal layer. In a transmission mode, and in a region other than the light transmission portion, a reflection mode.
[0051]
However, according to the transflective liquid crystal display device B, the light scattering function is provided by using the light scattering layer 12 made of the light scattering material on the outside of the glass substrate 1, but on the other hand, the reflection is mainly performed. External light used in the mode causes surface reflection on the surface of the light-scattering material, which causes a decrease in light use efficiency and a decrease in contrast of the liquid crystal display.
[0052]
On the other hand, according to the transflective liquid crystal display device A of the present invention, since the color filter 7a in which the transparent fine particles are dispersed is formed, it is not necessary to provide a light scattering material for scattering light rays outside the glass substrate. Also, surface reflection by the light scattering material can be eliminated, and as a result, the contrast in the reflection mode is improved.
[0053]
In addition, the color filter 7b, in which the transparent fine particles are not dispersed, is formed in a portion corresponding to the light transmitting portion. This complements that the color tone of the liquid crystal display becomes lighter in the transmission mode by using the color filter 7a alone. A high-performance transflective liquid crystal display device that can obtain optimum characteristics in both the mode and the reflection mode was obtained.
[0054]
As described above, a stripe-shaped laminated electrode group formed by arranging a laminate of a transparent conductive layer and a light-reflective metal layer on one principal surface of the substrate in a stripe pattern is formed, and is oriented on the stripe-shaped laminated electrode group. One member formed by laminating the layers, and the other member formed by sequentially laminating the stripe-shaped transparent electrode group and the alignment layer on the transparent substrate, the stripe-shaped laminated electrode group and the stripe-shaped transparent electrode group intersect. The pixels are arranged in a matrix by bonding through a super twisted nematic liquid crystal, and a light transmission part is provided for each pixel with respect to the light-reflective metal layer. Part) is a reflection mode, and when a color filter corresponding to a pixel is disposed on one member, a light filter is provided by dispersing a color filter in which transparent fine particles are dispersed. By lowering the color purity of the light-transmitting part, it was possible to prevent the light-transmitting part from deteriorating by adding a normal (no transparent fine particle dispersed) color filter to the part corresponding to the light-transmitting part. .
[0055]
It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the spirit of the present invention. For example, according to the above, the color filter 7a is formed, and then the color filter 7b is formed. Instead, the color filter 7b is formed earlier, and then the color filter 7a is formed. May be reversed.
[0056]
【The invention's effect】
As described above, according to the transflective liquid crystal display device of the present invention, the light reflecting metal layer is provided with the light transmitting portion corresponding to the end of the pixel, and the light transmitting portion is in the transmission mode. In the reflection mode in the area other than the light transmission area, and when arranging a color filter corresponding to the pixel on the other member, a light scattering function is provided by disposing a color filter with dispersed fine particles. In addition, the light scattering function provided outside the liquid crystal display cell can be provided inside the liquid crystal display cell. As a result, the efficiency of using external light rays can be improved, and the contrast during liquid crystal display can be improved.
[0057]
Further, according to the present invention, a color filter in which transparent fine particles are not dispersed is further laminated on a portion corresponding to the light transmitting portion, so that a decrease in color purity of the light transmitting portion can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a transflective liquid crystal display device of the present invention.
FIG. 2 is a sectional view of a conventional transflective liquid crystal display device.
FIG. 3 is a process chart for manufacturing one member (segment side) in the transflective liquid crystal display device of the present invention.
[Explanation of symbols]
1, 2, glass substrate 3, stripe-shaped transparent electrode group 4, Cr film 5, Al film 6, 10, alignment film 7a, color filter 7b in which transparent fine particles are dispersed ..Color filter 8 not dispersing transparent fine particles 8 ... Overcoat layer 9 ... Striped transparent electrode group 11 ... Liquid crystal layer

Claims (2)

A member formed by forming a laminate of a light reflecting film and a transparent electrode on a transparent substrate and coating an alignment layer, and a color filter containing light scattering particles, a transparent electrode, and an alignment film are sequentially laminated on the transparent substrate. And the other member is bonded via a nematic liquid crystal so that pixels are arranged in a matrix at both transparent electrodes, and a light transmitting hole is formed in the outer peripheral portion of the pixel with respect to the light reflecting film. A transflective liquid crystal display device in which another light reflecting film is provided on a portion of the other member on the transparent substrate corresponding to the outer peripheral portion of the pixel, and a light source is disposed on the outer surface side of the one member. 2. The transflective liquid crystal display device according to claim 1, wherein a color filter containing no light-scattering particles is provided at a portion of the other member corresponding to an outer peripheral portion of the pixel.

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