JPH11337720A - Color filter substrate and liquid crystal display device using the same - Google Patents

Abstract

(57) [Summary] In a conventional reflective color liquid crystal display device, high color purity and brightness are contradictory factors. When color purity is increased, darkness is increased, and when brightness is increased, color purity is decreased and high color purity is reduced. It was difficult to achieve both purity and brightness. A signal wiring line group serving also as a pixel electrode and a color filter group are provided on a substrate.
Are formed so as to overlap each other, the width of each color filter is smaller than or equal to the width of the corresponding signal wiring line, and no light-shielding layer is provided between adjacent color filters, so that the pixel Gain color purity at the center of the electrode,
The overall brightness is improved by increasing the amount of transmitted light around the pixel electrode of the color filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a color filter substrate, and more particularly, to a liquid crystal display device which performs color display using the color filter substrate.

[0002]

2. Description of the Related Art A color liquid crystal display device generally realizes color display by forming a fine color filter inside a panel. The color filter is obtained by applying an organic film containing a dye or a pigment on a substrate and finely processing the same by photolithography. When performing multi-color display, red,
Generally, green and blue color filters are formed for each dot. Here, the area of the color filter of each color is formed so as to be larger than the area of the pixel electrode for displaying the corresponding one dot. In general, a light-shielding layer is provided between adjacent pixel electrodes or between color filters. The liquid crystal display device having such a structure is used as a display device of a portable electronic device which has been rapidly spreading in recent years. This is because the liquid crystal display device has both lightness, thinness, low power consumption, and high display quality required for portable equipment. In many cases, a black-and-white or monochromatic reflective liquid crystal display device is used for applications requiring lower power consumption, and a transmissive color liquid crystal display device with a backlight is used for applications requiring higher display quality. .

[0003] In recent years, attention has been focused on a reflection type color liquid crystal display device aiming at high display quality such as brightness and high color purity even in a dark environment with the attractiveness of low power consumption.

The color filter of the reflection type color liquid crystal display device is formed by photolithography using an organic film containing a dye or a pigment similarly to the color filter of the transmission type color liquid crystal display device. However, since reflective color liquid crystal display devices effectively utilize external light, the color filters used are required to have high transmittance, and materials having lower color purity than the color filter materials of transmissive color liquid crystal display devices are required. They are usually used under different film forming conditions.

FIG. 2 is a plan view (a) of a structure of a conventional reflection type liquid crystal display device and a sectional view (b) of FIG.

On the color filter substrate 200, a light shielding film (black matrix) 201, R (red), G
(Green), B (blue) color filters 202, 203,
204, and a strip transparent electrode 206 via a protective film 205
An alignment film 207 is formed thereon. On the other hand, on the active element substrate 210, there is a transparent pixel electrode 212 connected to the signal line 211 by a MIM (metal / oxide / metal) element 213, and an alignment film 217 is formed. Liquid crystal 230 is sealed between the two substrates with a specific gap. A polarizing plate 208 is attached to one of the color filter substrates 200, and a polarizing plate 218 and a reflecting plate 219 are attached to the other active element substrate 210 in accordance with the designated transmission and absorption axes, respectively. The display is performed by controlling the amount of reflected incident light by the electric field between the electrodes applied to the liquid crystal.

[0007]

In the conventional reflection type color liquid crystal display device, high color purity and brightness are contradictory factors. It is common sense that the color purity becomes darker if the color purity is increased, and the color purity is reduced if the color purity is increased. However, there has been a difficulty in a method for achieving both high color purity and brightness.

Accordingly, it is an object of the present invention to provide a reflective type color liquid crystal display device which ensures color purity and brightness by supplementing brightness with emphasis on color purity. .

[0009]

According to the present invention, a color filter substrate is formed such that a signal wiring line group also serving as a pixel electrode and a color filter group are formed on a substrate so as to overlap on a plane, and the width of each color filter is one. Is smaller than or equal to the width of the corresponding signal wiring line, and no light-shielding layer is provided between adjacent color filters.

According to the above configuration, the color filter is used for a simple matrix type liquid crystal display device or an active matrix type liquid crystal display device using two-terminal type active elements such as MIM (metal / oxide film / metal). The width of the pixel electrode is smaller than or equal to the width of the corresponding signal wiring line, and the light-shielding layer is not provided between adjacent color filters. This has the effect of improving the overall brightness by increasing the purity and increasing the amount of transmitted light around the pixel electrode of the color filter.

Further, the color filter substrate of the present invention comprises:
A color filter group is formed on the substrate, and each color of the color filter is one of the pixel electrode groups of the liquid crystal display device.
It is formed corresponding to the dot, the area of the color filter arranged corresponding to the pixel electrode is the same or smaller than the area of the pixel electrode, and a light shielding layer is provided between adjacent color filters. It is not provided.

According to the above configuration, the color filter is used for an active matrix type liquid crystal display device using a TFT (thin film transistor), and each color of a color filter is formed corresponding to one dot of a pixel electrode group of the liquid crystal display device. The area of a color filter arranged corresponding to this pixel electrode is equal to or smaller than the area of a pixel electrode displaying one dot, and a light-shielding layer is provided between adjacent color filters. With such a structure, the color purity is gained at the center of the pixel electrode, and the amount of transmitted light around the pixel electrode of the color filter is increased to improve the overall brightness.

Further, a liquid crystal display device according to the present invention uses the color filter substrate according to the first or second aspect.

According to the above configuration, the use of a color filter having improved color purity and brightness has an effect that the color purity and brightness of the liquid crystal display device can be ensured.

Further, the liquid crystal display device of the present invention has a third aspect.
The liquid crystal display device described above, characterized in that a reflective layer is provided outside or inside a substrate constituting the liquid crystal display device, and display is performed by reflecting and absorbing external light.

According to the above arrangement, the reflective type color liquid crystal display has an effect that color purity and brightness can be secured.

Further, the liquid crystal display device of the present invention has a third aspect.
The liquid crystal display device according to claim 1, wherein a semi-transmissive layer and a luminous body are provided adjacent to the outside of the substrate, and the luminous body is illuminated, and the brightness of the surrounding environment is lower than the luminance of the luminous body. When the light is turned off or when the surrounding environment is brighter than the luminance of the light, the display is performed by reflecting and absorbing the light of the surrounding environment. Features.

According to the above configuration, the transflective / reflective type color liquid crystal display device has an effect that the color purity and brightness can be secured as a reflective type when the surrounding environment is bright and as a transmissive type when the surrounding environment is dark. Have.

[0019]

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

[First Embodiment] FIG. 1 is a view for explaining an embodiment of an MIM (metal / oxide film / metal) active matrix type liquid crystal display device using a color filter substrate according to the present invention. (A) is a structural plan view, (b) is the aa 'sectional drawing.

On the color filter substrate 100, R
(Red), G (green), B (blue) color filters 10
An alignment film 107 is formed on the strip transparent electrode 106 via the protective films 105, 103, and 104. On the other hand, on the active element substrate 110, there is a transparent pixel electrode 112 connected to the signal line 111 by an MIM (metal / oxide film / metal) element 113, and an alignment film 117 is formed. Liquid crystal 130 is sealed between the two substrates with a specific gap therebetween. Also, one color filter substrate 1
A polarizing plate 108 is attached to 00 and a polarizing plate 118 and a reflecting plate 119 are attached to the other active element substrate 110 so as to match the designated transmission / absorption axes, respectively. Is controlled by the electric field between the electrodes according to the above.

Here, there is no light shielding film (black matrix) on the color filter substrate 100, and the pixel electrode 1
12, the areas of the R (red), G (green), and B (blue) color filter layers are smaller or equal. Further, R (red), G (green), B
The width of the (blue) color filter layer is smaller or equal. Accordingly, light entering from the color filter substrate 100 side is given color purity by light passing through the color filter layer region, and in a region without the color filter layer, the incident light is directly reflected by the reflector 119 on the active element substrate 110 side. Therefore, brightness can be secured more than the conventional reflection type liquid crystal display device. Since the color purity is slightly lowered due to the combination of the two lights, the color purity can be increased by increasing the color purity of the color filter.

FIG. 3 shows a second embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a simple matrix type liquid crystal display device using a color filter according to the described invention.
(A) is a structural plan view, (b) is the aa 'sectional drawing.

Color filter substrate (common substrate) 30
On 0, an alignment film 307 is formed on the R (red), G (green), and B (blue) color filters 302, 303, and 304, and on the strip transparent electrode 306 via the protective film 305. . On the other hand, on the segment substrate 310, the segment electrodes 312 are arranged in a strip shape, and the alignment film 317 is formed. The liquid crystal 330 is separated by a specific gap between the two substrates.
Is enclosed. A polarizing plate 308 is attached to one common substrate 300, and a polarizing plate 318 and a reflecting plate 319 are attached to the other segment substrate 310 in accordance with the designated transmission / absorption axes, respectively. Is displayed by controlling the amount of reflected light by the electric field between the electrodes applied to the liquid crystal.

Here, there is no light-shielding film (black matrix) on the common substrate 300, and R (red), G (green), and G (green) are larger than the width of the strip-shaped segment electrode 312 and the strip-shaped common electrode 306. The width of the color filter layer of B (blue) is smaller. Therefore, light entering from the color filter substrate 300 side is given color purity by light passing through the color filter layer region, and in a region without the color filter layer, the incident light is directly reflected by the reflector 319 on the active element substrate 310 side. Therefore, brightness can be secured. Since the color purity is slightly lowered due to the combination of the two lights, the color purity can be increased by increasing the color purity of the color filter. [Third Embodiment] FIG. 4 is a view for explaining an embodiment of a TFT (thin film transistor) active matrix type liquid crystal display device using a color filter substrate according to the present invention. (A) is a structural plan view, (b) is the aa 'sectional drawing.

On the color filter substrate 400, R
(Red), G (green), B (blue) color filters 40
An alignment film 407 is formed on the common electrode 406 via the protective films 403, 404, and 404. On the other hand, on the active element substrate 410, there is a transparent pixel electrode 412 connected by a TFT (thin film transistor) 413 controlled by a signal line 411 and a scanning line 415, and an alignment film 417 is formed. Liquid crystal 430 is sealed between the two substrates with a specific gap. A polarizing plate 408 is attached to one of the color filter substrates 400, and a polarizing plate 418 and a reflecting plate 419 are attached to the other active element substrate 410 in accordance with designated transmission and absorption axes, respectively. The display is performed by controlling the amount of reflected incident light by the electric field between the electrodes applied to the liquid crystal.

Here, there is no light-shielding film (black matrix) on the color filter substrate 400, and the pixel electrode 4
12, the areas of the R (red), G (green), and B (blue) color filter layers are smaller or equal. Therefore,
Light entering from the color filter substrate 400 side is given color purity by light passing through the color filter layer region, and in a region without the color filter layer, the incident light is directly reflected by the reflector 419 on the active element substrate 410 side. Therefore, brightness can be secured more than the conventional reflective liquid crystal display device. Since the color purity is slightly reduced due to the combination of the two lights, the color purity can be increased by increasing the color purity of the color filter.

[Fourth Embodiment] FIG. 5 is a cross-sectional view of a transflective / reflective type color liquid crystal display device according to the present invention in which a reflection plate is arranged outside a substrate. This structure corresponds to a simple matrix type liquid crystal display device or an active matrix type liquid crystal display device using MIMs and TFTs.

Reference numeral 519 denotes a semi-transmissive reflection plate appropriately containing metal particles, and 540 denotes a backlight. When the backlight is turned on and the brightness of the surrounding environment is lower than the brightness of the backlight, display is performed by controlling the amount of light transmitted from the backlight by the electric field between the electrodes applied to the liquid crystal. Further, when the backlight is turned off or when the surrounding environment is brighter than the brightness of the backlight, the display is performed by controlling the amount of reflected light of the surrounding environment by the electric field between the electrodes applied to the liquid crystal.

Also in this embodiment, since the same color filter substrate 500 as that described in the first to third embodiments is provided, in a state where the color filter substrate 500 is used as a reflection type, the light enters from the color filter substrate 500 side. The light passing through the area of the color filter layer is given color purity by the light passing through the area of the color filter layer.
Since the light is reflected at 19, brightness can be secured.

[Fifth Embodiment] FIG. 6 is a sectional view of a reflection type color liquid crystal display device according to the present invention in which a reflection plate is arranged inside a substrate. This structure corresponds to a simple matrix type liquid crystal display device or an active matrix type liquid crystal display device using MIMs and TFTs.

Reference numeral 612 denotes a reflection plate made of thin-film aluminum, which can realize brighter display with higher color purity than in FIGS. 1, 3, 4, and 5. In addition, there is an advantage in that the image is not double seen by incorporating the reflection plate in the panel.

Also in this embodiment, since the same color filter substrate 600 as that described in the first to third embodiments is provided, light incident from the color filter substrate 600 side is emitted from the area of the color filter layer. Color purity is given by light passing through, and in a region without a color filter layer, incident light is directly reflected by the reflector 612 on the active element substrate 610 side, so that brightness can be secured.

In the first to fifth embodiments, the arrangement of the color filters is mosaic, but the same applies to the delta arrangement. The same applies to the use of cyan, magenta, and yellow, which are complementary colors of R, G, and B, as the colors of the color filters.

The reduction amount of the color filter area with respect to the pixel electrode area may be equalized for R, G, and B, or may be set in proportion to the transmission luminance of the color filter. Further, the reduction amount of the color filter area with respect to the pixel electrode area may be reduced as much as possible to increase the color purity, and may be increased to increase the brightness, but the color purity decreases accordingly. This is similar to the conventional structure, but can secure the brightness and the color purity as compared with the conventional case in which the color purity of the color filter itself is reduced to make it brighter.

[0036]

According to the present invention, a liquid crystal display device of a simple matrix system or M
In an active matrix liquid crystal display device using an IM, the width of a color filter is smaller than or equal to the width of a corresponding signal wiring line also serving as the pixel electrode,
In addition, by adopting a structure in which a light-shielding layer is not provided between adjacent color filters, color purity is obtained at a more central portion of the pixel electrode, and an amount of transmitted light is increased at a peripheral portion of the pixel electrode of the color filter, thereby increasing the overall amount. This has the effect that a high brightness can be improved.

In an active matrix type liquid crystal display device using a TFT (thin film transistor), each color of a color filter is formed corresponding to one dot of a pixel electrode group of the liquid crystal display device. Compared to the area of the pixel electrode for displaying the dots, the area of the color filter arranged corresponding to the pixel electrode is the same or smaller, and the light-shielding layer is not provided between the adjacent color filters. This has the effect of increasing the color purity at the center of the pixel electrode and increasing the amount of transmitted light at the periphery of the pixel electrode of the color filter, thereby improving the overall brightness.

Further, the color filter substrate of the present invention comprises:
Since it is possible to use the same color filter as a transmission type liquid crystal display device with high color purity, there is no need to change the filter material and manufacturing conditions, so that in terms of production line efficiency and quality stability, material procurement and management, etc. Is reduced, and as a result, the cost and quality of the color filter substrate can be reduced.

[Brief description of the drawings]

FIG. 1A is a structural plan view of a liquid crystal display device according to a first embodiment of the present invention, and FIG.

FIG. 2A is a plan view of a structure of a conventional liquid crystal display device, and FIG.

FIG. 3A is a structural plan view of a liquid crystal display device according to a second embodiment of the present invention, and FIG.

FIG. 4A is a structural plan view of a liquid crystal display device according to a third embodiment of the present invention, and FIG.

FIG. 5 is a cross-sectional view of a transflective / reflective type color liquid crystal display device according to the present invention, in which a reflecting plate is arranged outside a substrate.

FIG. 6 is a cross-sectional view of a reflective color liquid crystal display device according to the present invention in which a reflective plate is disposed inside a substrate.

[Explanation of symbols]

100, 200, 300, 400, 500, 600 ...
-Color filter substrates 102, 202, 302, 402, 502, 602-
・ R (red) color filter 103, 203, 303, 403, 503, 603
G (green) color filters 104, 204, 304, 404, 504, 604
-B (blue) color filter 105, 205, 305, 405, 505, 605-
-Protective film 106, 206, 306, 506, 606 ... Strip transparent electrode 107, 117, 207, 217, 307, 317, 4
07, 417, 507, 517, 607, 617 ...
Alignment film 108, 118, 208, 218, 308, 318, 4
08, 418, 508, 518, 608: Polarizing plate 119, 219, 319, 419, 519: Reflecting plate 110, 210, 410, 510, 610: Active element substrate 310: Segment substrate 111 , 211, 411, 511, 611 ... signal lines 112, 212, 412, 512, 612 ... pixel electrodes 312 ... segment electrodes 113, 213 ... MIM elements 413 ... thin film transistors 114, 214 , 414 ... pixel electrode connection electrode 415 ... scanning line 201 ... light shielding film (black matrix) 130, 230, 330, 430, 530, 630 ...
・ Liquid crystal 540 ・ ・ ・ Backlight

Claims (5)

[Claims] 1. A signal wiring line group also serving as a pixel electrode and a color filter group are formed on a substrate so as to overlap in a plane,
A color filter substrate, wherein the width of each color filter is smaller than or equal to the width of the corresponding signal wiring line, and no light shielding layer is provided between adjacent color filters. 2. A color filter group is formed on a substrate, and one color of each color filter is formed corresponding to one dot of a pixel electrode group of a liquid crystal display device. The color filter substrate according to claim 1, wherein the color filters arranged corresponding to the pixel electrodes have the same or smaller area, and no light-shielding layer is provided between adjacent color filters. 3. A liquid crystal display device using the color filter substrate according to claim 1. 4. The liquid crystal display device according to claim 3, wherein a reflection layer is provided on the outside or inside of the substrate, and display is performed by reflecting and absorbing external light. 5. A semi-transmissive layer and a luminous body are provided adjacent to the outside of the substrate, and the luminous body is turned on and the light of the luminous body is transmitted when the brightness of the surrounding environment is lower than the luminance of the luminous body. -The display is performed by shielding the light, and when the light emitting body is turned off or when the surrounding environment is brighter than the luminance of the light emitting body, the display is performed by reflecting and absorbing the light of the surrounding environment. Item 4. A liquid crystal display device according to item 3.