JP2004191646A - Transflective liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transflective liquid crystal display device which adjusts chromaticity in a reflection part without varying the chromaticity in a transmission part thereby keeping a display quality at a good level in . <P>SOLUTION: In the transflective liquid crystal display device 10 provided with a first substrate with a reflection electrode 16 and a transmission electrode 14 on its surface, a second substrate with color filter layers 12R, 12G, 12B on its surface opposite to the first substrate and a liquid crystal layer disposed between the first and second substrates, openings 32R, 32G, 32B are disposed on respective parts of the color filter layers 12R, 12G, 12B opposite to the reflection electrode 16 and color filter layers 32RB, 32GB with other colors are partially disposed on the openings of the color filter layers of some colors. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transflective liquid crystal display device, and more particularly to a transflective liquid crystal display device that can freely adjust chromaticity and has good display quality in a transflective liquid crystal display device in which an opening is provided in a color filter. The present invention relates to a display device.
[0002]
[Prior art]
In recent years, the application of liquid crystal display devices has rapidly spread not only in information communication equipment but also in general electric equipment. In particular, for portable devices, a reflective liquid crystal display device that does not require a backlight is used in order to reduce power consumption. This reflective liquid crystal display device uses external light as a light source. Moreover, it becomes difficult to see in a dark room. Therefore, in recent years, development of a transflective liquid crystal display device having both transmissive and reflective properties has been underway.
[0003]
This transflective liquid crystal display device has a transmissive portion having a transparent electrode and a reflective portion having a reflective electrode in one pixel, and in a dark place, the backlight is turned on to transmit the transmissive portion of the pixel region. Since the image is displayed using the external light in the reflective part without turning on the backlight in bright places, it is not necessary to always turn on the backlight. Can be greatly reduced.
[0004]
The configuration and operating principle of this transflective liquid crystal display device will be described with reference to FIGS. 3 is a plan view in which color filter layers 102R, 102G, and 102B are arranged for each sub-pixel in one pixel portion formed of three RGB sub-pixels of the transflective liquid crystal display device 100. FIG. FIG. 4 is a simplified cross-sectional view taken along line AA in FIG. 3. The color filter layers 102R, 102G, and 102B are general color filter layers of R, G, and B, respectively, and as shown in FIG. 3, a reflective portion and a thin film having a transmissive portion 104 and a reflective electrode 106. The field effect transistor (TFT) elements 108 are arranged in stripes so as to overlap the entire part. Reference numerals 109 and 110 denote scanning lines and video lines, respectively. In the transflective liquid crystal display device 100, as shown in FIG. 4, a reflective electrode 106 made of aluminum metal or the like is provided on the lower substrate 112 except for the transmissive portion 104 for each subpixel. Yes.
[0005]
On the other hand, an upper substrate 118 provided with color filters 102R, 102G, and 102B is disposed facing the lower substrate 112, and a predetermined liquid crystal material 120 is disposed between the upper substrate 118 and the lower substrate 112. A semi-transmissive liquid crystal display device is formed in combination with a polarizing plate, a backlight and the like (not shown).
[0006]
In such a transflective liquid crystal display device 100, the light from the backlight is transmitted only once in the color filter layer corresponding to the transmissive portion 104, but corresponds to the reflective portion having the reflective electrode 106. Since the color filter layer transmits twice when external light is incident and when it is reflected by the reflective electrode 106 and emitted, the transmittance of the reflective portion is about half of the transmittance of the transmissive portion 104, and the reflective portion In addition, there is a problem that it is difficult to realize a bright and high color purity color display in both the transmission part and the transmission part. Therefore, in a color filter for a transflective liquid crystal display device, it is necessary to provide a difference in transmittance or chromaticity between the above-described reflecting portion and the transmitting portion in order to realize a bright and high color purity color display. was there.
[0007]
As an example of a method for providing a difference in transmittance or chromaticity between the reflective portion and the transmissive portion of such a transflective liquid crystal display device, there is known a method performed by changing the thickness of the colored layer of the filter layer. However, if the chromaticity of the reflection portion is adjusted by this method, the chromaticity of the transmission portion also changes, and in addition, the color pattern (R, G, B) is changed by changing the film thickness. Since there is a large level difference between the cells, the cell gap becomes different for each color, leading to deterioration of display quality and an increase in manufacturing process.
[0008]
On the other hand, there is a difference in the transmittance or chromaticity of the color filter between the reflective portion and the transmissive portion of the transflective liquid crystal display device, and the color filter formed by one patterning is disclosed in Patent Document 2 below. Is disclosed. A specific example of the transflective liquid crystal display device 130 disclosed in Patent Document 2 will be described with reference to FIGS. FIG. 5 is a plan view in which color filter layers 142R, 142G, and 142B are arranged for each sub-pixel in one pixel portion composed of three sub-pixels of RGB. In FIG. 5, the color filter is only for one sub-pixel. The diagonal lines are omitted, and the other two subpixels are omitted. FIG. 6 is a simplified cross-sectional view along the line AA in FIG.
[0009]
5 and 6, a reflective electrode 136 and a transparent electrode 138 are formed in a predetermined shape for each sub-pixel on the lower substrate 134, and a color filter layer is formed on the color filter substrate 140 facing the reflective electrode 136 and the transparent electrode 138. 142R, 142G, 142B and a transparent electrode 144 are formed. Between the reflective electrode 136 and the transparent electrode 138 of the lower substrate 134 and the transparent electrode 144 formed on the color filter substrate 140, a vertically aligned liquid crystal material using a liquid crystal material exhibiting negative dielectric anisotropy. 146 is disposed, and a transflective liquid crystal display device 130 is formed in combination with a polarizing plate, a backlight, a quarter-wave plate, etc. (not shown). Note that 149 is a scanning line, and 150 is a video line.
[0010]
In this transflective liquid crystal display device, the color filter layers 142R, 142G, and 142B do not overlap all of the reflective electrodes 136, and always overlap all the transparent electrodes 138. It is provided in stripes. That is, the color filter substrate 140 of the transflective liquid crystal display device includes a portion where the color filter layers 142R, 142G, and 142B corresponding to the sub-pixels are formed in the portion corresponding to the reflective electrode 136 of each sub-pixel. The color filter layers 142R, 142G, 142B are not formed, and are not formed portions 148R, 148G, 148B. The brightness and color purity are adjusted to be optimum values for each color by changing the area ratio of the portion where the color filter is formed and the area ratio of the non-formed portion where the color filter is not formed. Usually, the area of the green filter non-formed part 148G is the largest, and the area of the blue filter non-formed part 148B is the smallest.
[0011]
In the transflective liquid crystal display device in which the non-formed portions 148R, 148G, and 148B are provided in the color filter layer, white is displayed in the non-formed portions of the color filter layer, and each color is formed in the portion where the color filter layer is formed. A color corresponding to the type of filter is displayed, and the two colors are mixed to realize a bright display necessary for the reflecting portion.
[0012]
[Patent Document 1]
JP-A-11-109333 (Claims 1 and 7)
[Patent Document 2]
JP 2000-111902 A (Claim 1, paragraph “0066”)
[0013]
[Problems to be solved by the invention]
According to such a transflective liquid crystal display device in which a non-formed part is provided in the color filter, it is possible to improve display in the reflective part and the transmissive part compared to the conventional transflective liquid crystal display apparatus. When the color filter was simply provided with a non-formed part and the size of the non-formed part was changed for each color filter, the display itself in the reflective part was originally yellowish. There was a new problem of being displayed.
[0014]
Accordingly, the inventors of the present application have repeated various experiments to solve the above-described problems in the transflective liquid crystal display device in which the color filter is provided with the non-formed part, and as a result, the predetermined color filter layer is not formed. It has been found that the color tone can be changed by partially forming a filter layer of another color. That is, for example, when a blue (B) color filter layer is partially formed in the opening of the red (R) or green (G) filter layer, the green or red component in the chromaticity coordinate system is shifted to the blue component side. In order to reduce the yellow component, the present inventors have found that the problem that the display of the transflective liquid crystal display device is yellowish can be solved, and the present invention is completed. It has come.
[0015]
In the present invention, an unformed portion of the color filter layer may be arranged on the side surface of the color filter according to the electrode arrangement of the transflective liquid crystal display device to be used. In the following, an unformed portion provided in the color filter layer is expressed as an “opening”.
[0016]
[Means for Solving the Problems]
That is, according to the present invention,
A first substrate having a reflective electrode and a transmissive electrode;
A second substrate having a color filter layer on a surface facing the first substrate;
A transflective liquid crystal display device having a liquid crystal layer disposed between the first substrate and the second substrate;
A transflective liquid crystal display device in which an opening is provided in a part of each color filter layer facing the reflective electrode, and a color filter layer of another color is partially provided in the opening of a color filter layer of a part of color Is provided.
[0017]
According to the transflective liquid crystal display device, it is possible to increase the brightness at the reflection portion, and the pixel is provided by another color filter layer partially provided in the opening of the color filter layer of some colors. Therefore, a transflective liquid crystal display device having a desired color tone can be obtained.
[0018]
In this case, the color filter layer of the other color is a blue (B) filter layer, and the color filter layer of the partial color is at least one of the red (R) and green (G) filter layers. It is preferable. By adopting such a configuration, the blue (B) component can be added to the red (R) or green (G) filter layer, so that the green component and the red component in the chromaticity coordinate system are shifted to the blue component side. Therefore, the yellow component can be reduced, so that the chromaticity of the transflective liquid crystal display device, which originally had a yellowish display, can be adjusted to normal chromaticity, and pure white display can be achieved. It becomes possible.
[0019]
In the transflective liquid crystal display device, it is preferable that the film thickness of the color filter layer of another color and the film thickness of the color filter layer of the partial color are the same. By adopting such a configuration, the change in the film thickness of the color filter layer is reduced in the reflective portion, so that the disorder of the alignment of the liquid crystal molecules based on the difference in the cell gap is reduced and high quality display can be performed.
[0020]
In the transflective liquid crystal display device, the color filter layer of another color is preferably provided in contact with a boundary portion of the color filter layer of the part of colors. By adopting such a configuration, the step difference is reduced as compared with the case where the color filter layer of the different color is provided separately from the color filter layer of the part of the color, so that the change in the cell gap is reduced in the reflection portion. Therefore, the alignment disorder of the liquid crystal molecules based on the difference in cell gap is reduced, and high quality display can be performed.
[0021]
Further, in the transflective liquid crystal display device, it is preferable that an auxiliary capacitance electrode is further provided on the first substrate, and at least a part of the opening is provided at a position facing the auxiliary capacitance electrode. Even in this case, since the first substrate is thick at the auxiliary capacitance electrode portion, the cell gap can be made constant, and the disorder of the alignment of the liquid crystal molecules due to the difference in the cell gap is reduced. High-quality display.
[0022]
Furthermore, in the transflective liquid crystal display device, a thin film field effect transistor (TFT) connected to the reflective electrode and the transmissive electrode is provided on the first substrate, and a part of the opening is the TFT. It is preferable to make it provided in the position which opposes. Since the TFT portion of the first substrate is usually thick, by adopting such a structure, the disorder of the alignment of liquid crystal molecules based on the difference in cell gap is reduced, and high-quality display can be performed. In addition, when there is no unevenness on the TFT, it is possible to secure a predetermined size opening by suppressing a reduction in reflection efficiency by such a configuration, so that a bright transflective liquid crystal display device can be obtained. become.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a specific example of the transflective liquid crystal display device of the present invention will be described in detail with reference to FIGS. 1 is a plan view in which color filter layers 12R, 12G, and 12B are arranged for each sub-pixel in one pixel portion formed from three sub-pixels of RGB of the transflective liquid crystal display device 10 of the present invention. FIG. 2 is a simplified cross-sectional view taken along line AA of FIG. The color filter layers 12R, 12G, and 12B are R, G, and B color filter layers, respectively. As shown in FIG. 1, a reflection unit that includes a transmission unit 14 and a reflection electrode 16 for each sub-pixel, and The TFT elements 18 are arranged in stripes so as to overlap the entire part. Reference numerals 19 and 20 denote scanning lines and video lines, respectively.
[0024]
As shown in FIG. 2, the transflective liquid crystal display device 10 is a reflection made of aluminum metal or the like via an insulating layer 24 on a lower substrate (first substrate) 22 except for a transmission portion 14. An electrode 16 is provided, and both the reflective electrode 16 and the transmissive portion 14 are covered with a transparent electrode 26 made of ITO or IZO (indium-zinc-oxide). The transparent electrode 26 is a contact hole portion 15. Thus, it is electrically connected to the drain electrode D of the TFT element 18. When such a configuration is adopted, the potential of the reflection portion and the potential of the transmission portion 14 are equal.
[0025]
On the other hand, an upper substrate (second substrate) 28 provided with color filter layers 12R, 12G, and 12B is disposed facing the lower substrate 22, and a predetermined liquid crystal is interposed between the upper substrate 28 and the lower substrate 22. The material 30 is disposed, and the transflective liquid crystal display device 10 is formed in combination with a polarizing plate, a backlight, and the like (not shown). Each of the color filter layers 12B, 12R, and 12G is provided with openings 32B, 32R, and 32G that do not have a colored portion, and the sizes of the openings are disclosed in Patent Document 2 above. Similarly, the area of the opening 32G of the green filter 12G is the largest, and the area of the opening 32B of the blue filter 12B is the smallest.
[0026]
In this specific example, simply providing the three openings 32R, 32G, and 32B results in a yellowish display, and therefore, among the three openings, the opening 32R of the red filter layer 12R and the green filter layer. Blue filter layers 32RB and 32GB are respectively provided in a part of the 12G opening 32G. The blue filter layers 32RB and 32GB may be provided in a part of at least one opening 32R or 32G of the red or green filter layers 12R and 12G, and are not necessarily provided in both of the two openings 32R and 32G. It is not necessary. In that case, desired color tone and brightness can be obtained by appropriately changing the size of the opening and the area of the blue filter layer provided in a part of the opening.
[0027]
In the above specific example, the blue filter layers 32RB and 32GB are provided so as to be in contact with the boundary between the opening 32R of the red filter layer 12R and the opening 32G of the green filter layer 12G, respectively. You may provide independently so that it may not contact the boundary part of 32R and 32G. However, since the blue filter layers 32GB and 32RB are provided so as to be in contact with the boundary portions of the openings 32G and 32R, respectively, as in the above specific example, the level difference on the surface of the color filter layer can be reduced. Since the disorder of the orientation of the liquid crystal molecules can be reduced in the reflection portion, the characteristic change of each pixel can be suppressed to a small level, and the display quality can be maintained at a good level.
[0028]
Further, the blue filter layer 32RB or 32GB is desirably provided to have the same film thickness as each filter layer 12R or 12G in order to keep the cell gap constant without changing the film thickness of the filter layer.
[0029]
In the transflective liquid crystal display device, since an auxiliary capacitance electrode (not shown) is provided below the reflective electrode 16 in parallel with the scanning line 19, the lower substrate 22 side is usually thick in the auxiliary capacitance electrode portion. It has become. Therefore, in order to maintain the cell gap between the lower substrate and the upper substrate as uniform as possible so that uniform color development is achieved, the openings 32R, 32G, and 32B of the filter layer are formed by the auxiliary capacitance electrodes. It is good to arrange in the part provided.
[0030]
In addition, the lower substrate 22 side is usually thick on the TFT 18. Therefore, the openings 32R, 32G, and 32B of the filter layer are disposed on the TFT 18 in order to keep the cell gap between the lower substrate and the upper substrate as uniform as possible so as to achieve uniform color development. May be. In addition, as shown in FIG. 2, the surface of the reflective electrode is usually provided with a concavo-convex portion in order to increase the reflection efficiency, but the TFT 18 portion has a reason that the insulating film 24 does not have a sufficient thickness. It is difficult to form the uneven portion, and the uneven portion is often not formed on the TFT 18. If it is not desired to form the opening of the filter layer on the concavo-convex portion for the purpose of maintaining the reflection efficiency, the size of the desired opening can be secured by forming the opening of the filter layer on the TFT 18 without the concavo-convex portion. It is also possible to achieve a desired brightness.
[0031]
【The invention's effect】
As described above, according to the present invention, the filter layer of a different color is partially formed in the opening of the predetermined color filter layer facing the reflective electrode, so that the color tone of the transmission part can be changed. In addition, since the color tone of the reflective portion can be freely adjusted, a transflective liquid crystal display device having a bright desired color tone can be obtained, and in addition, the film thickness of the color filter can be changed. Since the liquid crystal molecules can be less disturbed due to the difference in cell gap, the difference in characteristics of each pixel can be kept small, and high-quality transflective liquid crystal A display device can be obtained.
[Brief description of the drawings]
FIG. 1 is a plan view in which R, G, and B color filter layers are arranged in a transflective liquid crystal display device of the present invention.
FIG. 2 is a simplified cross-sectional view along the line AA in FIG.
FIG. 3 is a plan view in which R, G, and B color filter layers are arranged in a conventional transflective liquid crystal display device.
4 is a simplified cross-sectional view along line AA in FIG. 3;
FIG. 5 is a plan view in which R, G, and B color filter layers are arranged in another conventional transflective liquid crystal display device in which a transmission portion is provided in a color filter.
6 is a simplified cross-sectional view along line AA in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Transflective liquid crystal display device 12R, 12G, 12B Color filter layer 14 Transmission electrode 16 Reflection electrode 18 TFT element 19 Scan line 20 Video line 22 1st board | substrate 26 Transparent electrode 28 2nd board | substrate 32R, 32G, 32B Each color filter layer Opening 32RB Blue (B) filter layer 32GB provided in the opening 32R of the red (R) filter layer Blue (B) filter layer provided in the opening 32G of the green (G) filter layer

Claims (6)

A first substrate having a reflective electrode and a transmissive electrode;
A second substrate having a color filter layer on a surface facing the first substrate;
A transflective liquid crystal display device having a liquid crystal layer disposed between the first substrate and the second substrate;
A transflective device characterized in that an opening is provided in a part of the color filter layer facing the reflective electrode, and a color filter layer of another color is partially provided in the opening of a part of the color filter layer. Type liquid crystal display device. The color filter layer of another color is a blue (B) filter layer, and the color filter layer of the partial color is at least one of a red (R) and green (G) filter layer, The transflective liquid crystal display device according to claim 1. 3. The transflective liquid crystal display device according to claim 1, wherein a film thickness of the color filter layer of another color and a film thickness of the color filter layer of the part of colors are the same. 4. The transflective liquid crystal display device according to claim 3, wherein the color filter layer of another color is provided in contact with a boundary portion of the part of the color filter layers. The auxiliary capacitance electrode is further provided on the first substrate, and at least a part of the opening is provided at a position facing the auxiliary capacitance electrode. 2. A transflective liquid crystal display device according to item 1. A thin film field effect transistor (TFT) connected to the reflective electrode and the transmissive electrode is provided on the first substrate, and a part of the opening is provided at a position facing the TFT. The transflective liquid crystal display device according to any one of claims 1 to 5.

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