JPH10186347A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying a sufficiently bright color picture as the liquid crystal display device provided with color filters even when the device is a reflection type display displaying picture by utilizing an outer light. SOLUTION: This liquid crystal display device is constituted so that respective areas of color filters 14R, 14B, 14B are made smaller than the area of a pixel area A and only incident lights on the color filters 14R, 14B, 14B among lights transmitting pixel areas A receive absorptions of lights of their absorption wavelength bands by the color filters 14R, 14B, 14B to be colored and other lights transmit the pixel areas A by being kept in non-colored lights of high luminance without receiving absorptions by the color filters 14R, 14B, 14B and then color pixels are displayed with the non-colored lights and the colored lights.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device having a color filter.

[0002]

2. Description of the Related Art There are two types of liquid crystal display devices: a transmissive type that displays by using light from a backlight, and a reflective type that displays by using external light such as natural light or indoor illumination light. In a reflection type liquid crystal display device, a reflection member is disposed on the back side thereof to reflect external light incident from the front side of the arrangement device.

In general, a liquid crystal display device has a TN (Twisted Nematic) in which liquid crystal molecules of the liquid crystal layer are twist-aligned at a predetermined twist angle between both substrates.
In the TN method, polarizing plates are arranged on the outer surface of the one substrate and the outer surface of the other substrate, respectively, with their transmission axes directed in a predetermined direction.

Further, there are various types of liquid crystal display devices such as an active matrix type and a simple matrix type. For example, an active matrix type liquid crystal display device has a pair of substrates opposed to each other with a liquid crystal layer interposed therebetween. A plurality of pixel electrodes arranged in a matrix and a plurality of active elements respectively connected to these pixel electrodes are provided on the inner surface of one of the substrates, and the plurality of pixel electrodes are opposed to the plurality of pixel electrodes on the inner surface of the other substrate. A counter electrode for forming a pixel region is provided by the portion to be formed.

Further, there are a liquid crystal display device for displaying a black-and-white image and a liquid crystal display device for displaying a color image. In general, a liquid crystal display device for displaying a color image is one of the inner surfaces of a pair of substrates. Either of them is provided with a color filter corresponding to each pixel region.

That is, in the case of a liquid crystal display device for displaying a multicolor image such as a full-color image, a plurality of colors having an area covering the entire pixel region, for example, red, are provided on the inner surface of one of the substrates. Three color filters of green and blue are alternately arranged so that the color filters of the respective colors correspond to adjacent pixel regions.

[0007]

However, in a conventional liquid crystal display device having a color filter, all of the light transmitted through the pixel region is incident on the color filter, and the light in the absorption wavelength range is absorbed by the color filter. Is absorbed and colored to the color of the color filter, so that there is a problem that light attenuation is large and a bright display cannot be obtained.

This problem can be alleviated to some extent by increasing the brightness of the backlight in the case of the above-mentioned transmissive display device. However, in the case of a reflective liquid crystal display device which makes use of external light for display. The brightness of the external light that is incident is affected by the brightness of the surroundings, and a color filter is used until the light incident from the front side is reflected by the reflection member on the back side and exits to the front side. Twice, the attenuation of light is further increased, and the screen becomes dark enough that the displayed image cannot be identified.

It is an object of the present invention to provide a liquid crystal display device having a color filter, which can display a sufficiently bright color image even if it is a reflection type display device using external light for display. It is intended for.

[0010]

According to the present invention, there is provided a liquid crystal display device comprising: a pair of substrates opposed to each other; a plurality of first electrodes provided on an inner surface of one of the pair of substrates; At least one second region that forms a pixel region on the inner surface of the other substrate by a portion facing the plurality of first electrodes.
And a color filter provided on one of the inner surfaces of the pair of substrates so as to correspond to the pixel region and having a smaller area than the pixel region, and provided between the pair of substrates. A liquid crystal layer; and a reflection member that reflects light transmitted through the liquid crystal layer.

According to the liquid crystal display device of the present invention, since the area of the color filter is smaller than the area of the pixel region, only the light that is incident on the color filter out of the light transmitted through the pixel region is absorbed by the color filter. The light in the region is absorbed and colored, and other light is transmitted as it is without being absorbed by the color filter and remains uncolored light of high luminance, and color pixels are displayed with the uncolored light and the colored light. You.

For this reason, the displayed color pixels are colored pixels of the color filter and have sufficient luminance. Therefore, according to this liquid crystal display device, external light incident from the surface side is reflected. A sufficiently bright color image can be displayed even if it is of a reflection type in which reflection is performed by a member for display.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the liquid crystal display device of the present invention is configured such that the area of the color filter provided on the inner surface of one of the substrates so as to correspond to the pixel area is smaller than the area of the pixel area. A color pixel that is displayed with uncolored light that does not pass through a color filter and light that is colored by the color filter, so that a sufficiently bright color image can be displayed even with a reflective display device. It is.

In the liquid crystal display device of the present invention, for example, a plurality of first electrodes and an active element connected to each of the first electrodes are provided on the inner surface of one of the pair of substrates. The region where the first electrode and the second electrode provided on the inner surface of the other substrate face each other is a pixel region.

Further, in the present invention, it is preferable that the color filter is provided so as to correspond to a region inside the pixel region except for a peripheral portion. Further, when a multicolor image is displayed, a plurality of color filters having different colors may be arranged at equal intervals, and these color filters may correspond to different pixel regions.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a part of the liquid crystal display device of this embodiment, and FIG. 2 is a sectional view taken along the line II-II of FIG.

The liquid crystal display device of this embodiment is of an active matrix type using a TFT (thin film transistor) as an active element. Of the pair of substrates (transparent substrates made of a glass plate or the like) 1, 2 On the inside of 1,
Transparent pixel electrodes 3 are arranged in a matrix and provided with an active element (hereinafter referred to as TFT) 4 composed of a plurality of TFTs connected to these pixel electrodes 3 respectively.
Is provided.

The TFT 4 is formed by forming a gate electrode 5 formed on the back substrate 1, a gate insulating film 6 covering the gate electrode 5, and formed on the gate insulating film 6 so as to face the gate electrode 5. I-type semiconductor film 7 and a source electrode 8 and a drain electrode formed via an impurity-doped n-type semiconductor film (not shown) formed on the source / drain regions of i-type semiconductor film 7. It consists of nine.

On the back substrate 1, a gate line 10 for supplying a gate signal to the TFT 4 of each row is wired along one side of each pixel electrode row.
The gate electrodes 5 of the TFTs 4 in each row are formed integrally with a gate line 10 corresponding to the row.

The gate insulating film (transparent film) 6 of the TFT 4 is formed over substantially the entire surface of the substrate 1, and the gate line 10 is covered with the gate insulating film 6 except for its terminal. .

On the gate insulating film 6, each TFT 4 of each column is arranged along one side of each pixel electrode column.
A data line 11 for supplying a data signal is connected to the data line 11, and a drain electrode 9 of the TFT 4 in each column is connected to the data line 11 corresponding to the column.

In this embodiment, the data line 11 is wired on the gate insulating film 6, and the drain electrodes 9 of the TFTs 4 in each column are respectively connected to the data line 1 corresponding to the column.
1 are integrally formed.

The pixel electrode 3 is formed on the gate insulating film 6, and this pixel electrode 3 is connected to the source electrode 9 of the corresponding TFT 4 at one side edge.

Further, an overcoat insulating film 12 is provided on the inner surface of the back substrate 1 to cover the TFT 4, the data line 11, and the peripheral portion of the pixel electrode 3, and an alignment film 13 is formed thereon. I have.

On the other hand, on the inner surface of the front substrate 2 serving as a display surface, color filters 14R, 14G, and 14B of a plurality of colors, for example, red, green, and blue, are provided on each pixel electrode 3 of the back substrate 1. A black mask 15 corresponding to the gap between the pixel electrodes 3 is provided between the color filters 14R, 14G, and 14B, and a transparent protective insulating film is provided to cover these. 16
Is formed on the protective insulating film 16 so as to oppose all of the pixel electrodes 3 and to form a pixel region A by a portion opposing the pixel electrodes 3 to form a pixel region A. An electrode 17 is provided, and an alignment film 17 is formed thereon.

The color filters 14R, 14G, 14
B indicates the red filter 1 in the row direction and the column direction, respectively.
4R, green filter 14G, and blue filter 14B are alternately arranged in this order and arranged at equal intervals, and these color filters 14R, 14G, and 14B correspond to different pixel regions A, respectively.

Each of these color filters 14R, 1
4G and 14B are color filters each having a size smaller than the area of the pixel region A in which the pixel electrode 3 and the counter electrode 17 face each other.
The color filters 14R, 14G, and 14B of the respective colors are provided corresponding to the inner regions except the peripheral portion of each pixel region A.

In the drawing, the color filters 14R, 14R,
Although 14G and 14B are formed in a rectangular shape, the shape of these color filters 14R, 14G and 14B is not limited to a rectangular shape, and may be a circular or elliptical shape.

The black mask 15 is provided for improving the definition of the display pixels. The black mask 15 is formed in a lattice pattern in which a portion corresponding to each pixel area A is opened. ing. The black mask 15 shown in FIG. 1 is formed of a metal film such as Cr (chromium).
May be formed of a resin to which a pigment of a black color or a color close to black is added.

Each opening 15a of the black mask 15
Is formed to have substantially the same shape as the pixel electrode 3 and a size slightly smaller than the pixel electrode 3 so that the peripheral portion of the opening 15a faces the peripheral portion of the pixel electrode 3 with a slight overlap width. ing.

The back substrate 1 and the front substrate 2 are
The liquid crystal 20 is filled in a region surrounded by the sealing material between the two substrates 1 and 2 through a frame-shaped sealing material (not shown).

An alignment film (horizontal alignment film made of polyimide or the like) provided on the inner surfaces of the pair of substrates 1 and 2
3.18, the alignment process is performed by rubbing the film surface in a predetermined direction, and the molecules of the liquid crystal 20 filled between the substrates 1 and 2 are aligned with the alignment film 13 of the back substrate 1.
And the alignment film of the front substrate 2, the respective substrates 1, 2
Is controlled in a twist direction between the substrates 1 and 2 at a predetermined twist angle (for example, approximately 90 °).

Polarizing plates 21 and 22 are disposed on the outer surfaces of the pair of substrates 1 and 2, respectively. These polarizing plates 21 and 22 have their optical axes (transmission axes or absorption axes). It is provided in a state facing a predetermined direction.

A reflecting member 23 for reflecting external light that has entered the liquid crystal display device from the front surface side and transmitted through the liquid crystal layer is disposed behind the rear surface of the polarizing plate 22. The reflection member 23 is formed of a white scattering reflection plate.

This liquid crystal display device is of a reflection type for displaying by using external light. Of the light (linearly polarized light) transmitted through the front polarizing plate 21 from the front side and incident on each pixel area A, The light that passes through the region inside the pixel region A except for the peripheral portion is the color filter 14 corresponding to the pixel region A.
R, 14G, and 14B, the light in the absorption wavelength range is absorbed by the color filter and colored in the color filter, and the colored light is sequentially transmitted through the liquid crystal layer and the back-side polarizing plate 22 and reflected. The light is reflected by the member 23, passes through the back-side polarizing plate 22, the liquid crystal layer, the color filter, and the front-side polarizing plate 21, and is emitted to the front side.

Of the light incident on each pixel area A, the light incident on the periphery of the pixel area A, that is, the area outside the color filters 14R, 14G, and 14B does not pass through the color filters. Liquid crystal layer and back-side polarizing plate 22
Are sequentially transmitted, reflected by the reflection member 23, sequentially transmitted through the back-side polarizing plate 22, the liquid crystal layer, and the front-side polarizing plate 21, and emitted to the front side.

According to this liquid crystal display device, since the area of the color filters 14R, 14G, 14B is smaller than the area of the pixel area A, the light transmitted through the pixel area A is incident on the color filters 14R, 14G, 14B. Only the light to be absorbed is colored by absorbing the light in the absorption wavelength range by the color filter, and the other light is transmitted as a high-luminance uncolored light without being absorbed by the color filter. Color pixels are displayed with the colored light.

FIG. 3 is a view showing one display pixel of the liquid crystal display device.
However, the periphery is a high-luminance non-colored area (white area that is the color of the reflection member 23) b, and the center is a colored area a colored with the color of the color filter.
Appears as one color pixel in which both the display of the colored region a and the display of the uncolored region b are mixed.

Therefore, according to the liquid crystal display device, the color pixels to be displayed are formed by the color filters 14R, 14R.
The pixels are colored in the colors of G and 14B and have sufficient luminance. Therefore, according to this liquid crystal display device, a reflection type in which external light incident from the surface side is reflected by the reflection member 23 for display. However, a sufficiently bright color image can be displayed.

In the reflection type liquid crystal display device, light incident near the edge of the pixel area A may be reflected by the reflection member and transmitted through the vicinity of the edge of the adjacent pixel area and emitted. .

In this case, in the conventional liquid crystal display device, since the color filter corresponds to the entire pixel area, light incident near the edge of the pixel area is also colored with the color of the color filter in the pixel area. The light is reflected by the reflection member, passes through the vicinity of the edge of the adjacent pixel region, and exits, so that color mixing occurs near the edge of the display pixel.

However, according to the liquid crystal display device of the above embodiment, since the area of the color filters 14R, 14G and 14B is smaller than the area of the pixel area A, any of the pixel areas A
In this case, light incident near the edge is reflected without coloring, and therefore, even if the light passes through the vicinity of the edge of the adjacent pixel area and exits, the light is near the edge of the display pixel. No color mixing occurs.

Further, in the above embodiment, the color filters 14R, 14G, and 14B are provided so as to correspond to the inner region except the peripheral portion of the pixel region A. The light incident near the edge is reflected without coloring, and therefore, the color mixture near the edge of the display pixel due to the light passing through and emitting near the edge of the adjacent pixel area is reduced. It can be prevented over almost the entire circumference of the pixel.

In the above embodiment, the color filter 1
4R, 14G, and 14B are formed on the substrate 2 provided with the counter electrode 17, and the color filters 14R, 14G,
14B may be formed on the substrate 1 on which the pixel electrodes 3 are provided.

Although the liquid crystal display device of the above embodiment is of the active matrix type, the present invention is not limited to the active matrix type, and a plurality of scanning electrodes along one direction may be formed on the inner surface of one substrate. The present invention can also be applied to a simple matrix type liquid crystal display device or the like in which a plurality of signal electrodes are provided in parallel and a plurality of signal electrodes are provided on the inner surface of the other substrate along a direction intersecting the scanning electrodes.

Also in this case, a color filter having an area smaller than the area of the pixel region is provided on the inner surface of one of the substrates so as to correspond to each pixel region where each scanning electrode and each signal electrode face each other. For example, similarly to the above-described embodiment, a sufficiently bright color image can be displayed even in a reflective liquid crystal display device that displays using external light.

[0047]

According to the liquid crystal display device of the present invention, since the area of the color filter is smaller than the area of the pixel region, only the light incident on the color filter out of the light transmitted through the pixel region is colored. The light in the absorption wavelength range is absorbed by the filter to be colored, and the other light is transmitted as it is as a high-luminance uncolored light without being absorbed by the color filter. Color pixels are displayed.

For this reason, the displayed color pixels are colored with the color of the color filter and have sufficient luminance. Therefore, according to this liquid crystal display device, external light incident from the surface side is reflected. A sufficiently bright color image can be displayed even if it is of a reflection type in which reflection is performed by a member for display.

Moreover, if the area of the color filter is smaller than the area of the pixel region, light incident near the edge of the pixel region is reflected by the reflecting member and transmitted through the vicinity of the edge of the adjacent pixel region. Even if the light is emitted, the light is uncolored light, so that color mixing does not occur near the edge of the display pixel.

In this case, if the color filter is provided corresponding to the inner region except for the peripheral portion of the pixel region, the light incident near the peripheral portion of the pixel region in any region of the peripheral portion of the pixel region is uncolored. Since the light is reflected as it is, color mixing near the edge of the display pixel can be prevented over almost the entire periphery of the pixel.

[Brief description of the drawings]

FIG. 1 is a plan view of a part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a diagram showing one display pixel of the liquid crystal display device.

[Explanation of symbols]

 1, 2 ... substrate 3 ... pixel electrode 4 ... TFT (active element) 14R, 14G, 14B ... color filter 15 ... black mask 17 ... counter electrode A ... pixel area A '... display pixel a ... colored area b ... uncolored area

Claims (4)

[Claims] A pair of first and second substrates provided on an inner surface of one of the pair of substrates;
And at least one second electrode that forms a pixel region on the inner surface of the other substrate with a portion facing the plurality of first electrodes, and the pixel on one of the inner surfaces of the pair of substrates. A color filter having an area smaller than the area of the pixel region, provided in correspondence with the region, a liquid crystal layer provided between the pair of substrates, and a reflecting member that reflects light transmitted through the liquid crystal layer. A liquid crystal display device comprising: 2. An inner surface of one of a pair of substrates,
A region where a plurality of first electrodes and an active element connected to each of the first electrodes are provided, and the first electrode and a second electrode provided on the inner surface of the other substrate face each other. 2. The liquid crystal display device according to claim 1, wherein? 3. The liquid crystal display device according to claim 1, wherein the color filter is provided so as to correspond to a region inside the pixel region except for a peripheral portion. 4. The liquid crystal display device according to claim 1, wherein a plurality of color filters having different colors are arranged at equal intervals from each other, and these color filters correspond to different pixel regions, respectively. .