JP2000250067A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of parallax due to thickness of the glass substrate between incident light and exit light, and to obtain a reflection and transmission integrated type liquid crystal display device. SOLUTION: This liquid crystal display device is provided with an insulating TFT substrate, which is provided with TFTs, reflection display electrodes 50 connected to the TFTs and having windows 60 partially consisting of transparent electrodes made of a transparent material, and color filters, and with reflection bodies 61 for reflecting light incident from the TFT substrate side to the reflection display electrodes 50 provided on the TFT substrate in positions corresponding to the windows 60. Spacers 70 are formed between the windows 60 and the reflection bodies 61 and a liquid crystal which has positive dielectric anisotropy is filled between both substrates 10, 30. Also an optical retardation plate and a polarizing plate are provided outside the both substrates. Because no optical retardation occurs between the windows 60 and the reflection bodies 61, a liquid crystal display device with both functions of a reflection type and a transmission type can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having both reflection and transmission.

[0002]

2. Description of the Related Art Conventionally, a so-called reflection type liquid crystal display device having a function of reflecting light incident from an observation direction and viewing a display, and a display device in which light is incident from a side opposite to an observer and light is transmitted therethrough. There has been proposed a reflection type and transmission type liquid crystal display device integrated with a so-called transmission type liquid crystal display device having a function of viewing the display.

FIG. 4 is a sectional view of a conventional reflective and transmissive liquid crystal display device taken along line AA in FIG. 1, and FIG. 5 is a sectional view taken along line BB in FIG. Show.

As shown in FIGS. 4 and 5, a conventional reflective and transmissive liquid crystal display device has a thin film transistor (hereinafter, referred to as a TFT) as a switching element on an insulating substrate 10 made of quartz glass, non-alkali glass or the like. ".)
Are formed.

First, a gate electrode 11 made of a refractory metal such as chromium (Cr) and molybdenum (Mo), a gate insulating film 12, and an active layer made of a polycrystalline silicon film are formed on an insulating substrate (TFT substrate) 10. 13 are formed in order.

The active layer 13 has a channel 13c above the gate electrode 11, and a source 13s and a drain 1 formed on both sides of the channel 13c by ion implantation using the stopper insulating film 14 on the channel 13c as a mask.
3d is provided.

Then, an SiO ₂ film, a SiN film, and the like are formed on the entire surface of the gate insulating film 12, the active layer 13, and the stopper insulating film 14.
An interlayer insulating film 15 is formed by laminating a film and an SiO ₂ film in this order, and a contact hole provided corresponding to the drain 13 d is filled with a metal such as aluminum (Al) to form a drain electrode 16. Further, a flattening insulating film 17 made of, for example, an organic resin and flattening the surface is formed on the entire surface. Then, a contact hole is formed at a position corresponding to the source 13s of the planarization insulating film 17, and an ITO (Indium) contacting the source 13s through the contact hole.
A transparent display electrode 19 made of Tin Oxide, which is a transparent electrode also serving as a source electrode, is formed on the flattening insulating film 17. Then, an alignment film 20 made of an organic resin such as polyimide for aligning the liquid crystal 21 is formed on the transparent display electrode 19. On the side opposite to the side on which the transparent display electrodes 19 are provided, a phase difference plate 22, a polarizing plate 23, and a semi-transmissive mirror 24 are sequentially stacked from the TFT substrate 10 side. The semi-transmissive mirror 24 has a function of reflecting and transmitting incident light.

[0008] A counter electrode substrate 30, which is made of an insulating substrate and faces the TFT substrate 10, has
A color filter 31 including a black matrix 32 having each color of red (R), green (G), and blue (B) and a light shielding function, a protective film 33 made of a resin formed thereon, and an ITO formed on the entire surface. , And a polarizing plate 44 is disposed on the opposite surface, that is, on the observer side 101. Then, the periphery of the counter electrode substrate 30 and the periphery of the TFT substrate 10 are adhered by a seal adhesive (not shown), and a space formed thereby is filled with a twisted nematic (TN) liquid crystal 21.

[0009] A backlight 51 as a light source is provided on the TFT substrate 10 side of the liquid crystal display device thus completed.

Here, how the light travels when used as a reflective liquid crystal display device will be described.

The natural light 100 incident from the outside is shown in FIG.
As shown by the broken arrow in the middle, the polarizing plate 4 on the observer 101 side
4, the opposite electrode substrate 30, the color filter 3
1, protective film 33, counter electrode 34, alignment film 35, TN liquid crystal 21, alignment film 20 on TFT substrate 10, transparent display electrode 1
9, the flattening insulating film 17, the interlayer insulating film 15, the gate insulating film 12, the TFT substrate 10, and the polarizing plate 23, are reflected by the semi-transmissive mirror 24, and then transmitted through each layer in the direction opposite to the incident direction. The light exits from the polarizing plate 44 on the counter electrode substrate 30 and enters the eyes 101 of the observer.

When used as a transmission type liquid crystal display device, the light 1 of the backlight 51 is applied from the TFT substrate 10 side.
When light is incident on the polarizing plate 23 and T, as shown by a solid line arrow in FIG.
FT substrate 10, gate insulating film 12, interlayer insulating film 15, flattening insulating film 17, transparent display electrode 19, alignment film 20, TN
The light passes through the liquid crystal 21, the alignment film 35, the counter electrode 34, the protective film 33, the color filter 31, the counter electrode substrate 30 and the polarizing plate 44 and enters the eyes of the observer 101.

[0013]

However, as shown in FIG. 5, when used as a reflection type, when the incident natural light enters and travels as shown by a dashed arrow 100, the light is transmitted through a semi-transmissive mirror. The light reflected by 24 will again pass through the TFT substrate 10 made of glass.
Therefore, there is a disadvantage that parallax occurs between the incident light and the emitted light due to the thickness of the glass substrate.

Further, for example, light incident on a red display pixel (R) is emitted to an adjacent green display pixel (G), and as a result, the R and G colors are blurred as a display. There was a disadvantage that it would be lost.

Accordingly, the present invention has been made in view of the above-mentioned conventional disadvantages, and an object of the present invention is to provide a transflective integrated type liquid crystal display device capable of obtaining a display with no parallax and without color fringing. Aim.

[0016]

A liquid crystal display device according to the present invention includes a display pixel region in which a plurality of gate signal lines and a plurality of drain signal lines are arranged so as to cross each other and are arranged in a matrix. A thin film transistor connected to a line and a reflective display electrode made of a reflective material connected to the thin film transistor are provided in the display pixel region, and a part of each of the reflective display electrodes has a window made of a transparent material that transmits light. A first substrate, a counter electrode made of a transparent conductive material provided to face each of the reflective display electrodes,
And a second substrate provided with a reflector for reflecting light incident from the substrate side to the first substrate side at a position corresponding to each of the windows, and a liquid crystal having a positive dielectric anisotropy is provided. A material that does not cause a phase difference of light incident from the first substrate side is disposed between the reflector and the window,
A polarizing plate and a retardation plate are provided on the first and second substrates on the side where the liquid crystal is not filled, respectively. The polarizing plate and the retardation plate are circular in the same direction as viewed from the second substrate side. They are arranged to generate polarized light.

Further, the present invention provides a liquid crystal display device wherein the material which does not cause the phase difference is an acrylic resin.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device having both reflection and transmission functions according to the present invention will be described below.

FIG. 1 is a plan view of the liquid crystal display device of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. FIG.

As shown in FIG. 1, a plurality of gate signal lines G
In addition, a reflective display electrode 50 is provided in a display pixel region surrounded by a plurality of drain signal lines D. A window 60 formed by removing the material of the reflective display electrode 50 is formed substantially at the center of the reflective display electrode 50. This window 60
Is transmitted from a backlight 51 described later. Also,
The window 60 is provided so as to overlap with the reflector 61 provided above the window 60. It is preferable that the reflector 61 is larger than the window 60 so that the incident light can be completely reflected. Between the window 60 and the reflector 61, a spacer 70 made of a substance that does not cause a phase difference of light incident from the TFT substrate 10 side, for example, an acrylic resin is formed.

As shown in FIG. 2, a TFT as a switching element is formed on an insulating substrate 10 made of quartz glass, non-alkali glass, or the like.

One of the insulating substrates (TFT substrate) 10
Gate electrode 11 made of high melting point metal such as Cr and Mo
Since the steps from the formation of the substrate to the formation of the planarization insulating film 17 are the same as those of the conventional structure, the description is omitted.

On the flattening insulating film 17, A is connected to the source 13s of the active layer 13 made of a polycrystalline silicon film.
1. A reflective display electrode 50 made of a conductive reflective material such as silver (Ag) is formed. As shown in FIGS. 1 and 3, the reflective display electrode 50 has a window 6 formed by removing the conductive reflective material substantially at a part of the central portion of the reflective display electrode 50.
0 is provided. A transparent material such as I
A transparent electrode made of TO is formed. That is, the window 60 is filled with a transparent material. A color filter 31 for each of R, G, and B is provided only on the reflective display electrode 50. The color filter 3 is placed on the window 60.
1 is not provided. Then, a protective film 33 made of an acrylic resin or the like for protecting the color filter 31 is provided on the color filter 31.

A spacer 70 made of an acrylic resin is provided at a position corresponding to the window 60. This spacer 70 is formed as follows.

After the protective film 33 of the color filter 31 is formed, a photo-curable resist, which is an acrylic resin, is applied to the entire surface of the TFT substrate 10 by a spinner or the like.
Using a mask in which the resist remains at the position corresponding to the window 60, light is irradiated and cured to form the spacer 70 at the position corresponding to the window 60. The thickness of this spacer 70 is
3 is set according to the distance between the reflectors 61 provided on the counter electrode substrate 30.

After the spacer 70 is formed in this manner, an alignment film 20 made of polyimide or the like and aligning the liquid crystal 21 is formed.

On the other side of the counter electrode substrate 30 on which the liquid crystal 21 is provided, a reflector 61 made of a metal such as Al that reflects light and having a shape corresponding to the window 60 provided in each reflective display electrode 50 is provided.
Is provided. The surface of the reflector 61, that is, the TFT substrate 10
The side may have an uneven shape to diffuse the incident light. The sectional shape of the reflector 61 may be hemispherical or triangular other than that shown in FIG. 3 as long as it reflects light to the reflective display electrode 50. A counter electrode 34 facing each reflective display electrode 50 is provided in a region other than the reflector 61. Further, an alignment film 35 made of polyimide is formed on the entire surface.
Are formed. A black matrix 32 made of black resin or the like is provided between the reflective display electrodes 50, that is, around the reflective display electrodes 50, at a position corresponding to the drain signal line D in order to shield light and improve contrast. ing.

On the side of the counter electrode substrate 30 where the liquid crystal 21 is not arranged, that is, on the observer 101 side, the phase difference (λ / 4)
A plate 43 and a polarizing plate 44 are provided in order from the counter electrode substrate 30 side.

The thus formed counter electrode substrate 30 and T
The periphery of the FT substrate 10 is adhered with a seal adhesive (not shown), and the liquid crystal 21 is filled in the gap formed thereby to complete the reflection and transmission integrated liquid crystal display device. The liquid crystal 21 is a twisted nematic (TN) liquid crystal having a positive dielectric anisotropy. TFT substrate 1
On the 0 side, a light source 51 such as a fluorescent tube backlight is provided.

Here, how the light travels when the above-mentioned liquid crystal display device is used as a reflection type liquid crystal display device will be described.

Natural light 10 incident from the observer 101 side
As shown by a dotted arrow in FIG. 3, 0 is incident from the polarizing plate 44 on the observer 101 side, passes through the phase difference plate 43, and further passes through the counter electrode substrate 30, the counter electrode 34, the alignment film 35, and the liquid crystal. 21 and the alignment film 20 on the TFT substrate 10,
The light reaches the color filter 31, the protective film 33, and the reflective display electrode 50 made of a reflective material. The arriving light is reflected by the reflective display electrode 50, follows the reverse optical path of the incident light, exits outside, and is observed by the observer 101.

Here, the polarization state of light when used as a reflection type will be described. In the following description of the polarization state, a case where no voltage is applied to the liquid crystal will be described.

The light incident from the counter electrode substrate 30 side passes through the polarizing plate 44 to become linearly polarized light, and becomes, for example, clockwise circularly polarized light by the phase difference plate 43. become. In that polarization state, the light reaches the reflective display electrode 50 and is reflected and the phase is inverted. By passing through the liquid crystal 21 again, the light becomes counterclockwise circularly polarized light and reaches the retardation plate 43 again. Then, the light becomes linearly polarized light vibrating in the same direction as the transmission axis of the polarizing plate 44, and the light is transmitted and emitted.

Next, how the light travels when the above-mentioned liquid crystal display device is used as a transmission type will be described.

As shown by a solid line in FIG. 3, the light 102 emitted from the backlight 51 is divided into a polarizing plate 23, a phase difference plate 22, a TFT substrate 10, a gate insulating film 12, an interlayer insulating film 15, a planarizing insulating film. The TF of the reflector 61 formed on the counter electrode substrate 30 is transmitted through the film 17 and the window 60 provided in the reflective display electrode 50, and then transmitted through the spacer 70.
The light is reflected on the surface on the side of the T substrate 10 and is incident on the color filter 31 to reach the reflective display electrode 50, where it is reflected again and is oriented on the counter electrode substrate 30, the alignment film 35,
The light passes through the counter electrode substrate 30, the phase difference plate 43, and the polarizing plate 44 and is emitted and observed by the observer 101.

Here, the polarization state of light when used as a transmission type will be described.

As shown by a solid line in FIG. 3, the light 102 emitted from the backlight 51 enters the polarizing plate 23 and becomes linearly polarized light, and then becomes counterclockwise circularly polarized light by the phase difference plate 22. . Thereafter, the light passes through the transparent electrode of the window 60 and passes through the spacer 70. At this time, since there is no phase difference of light, the light reaches the reflector 61 in a counterclockwise circularly polarized state.

Then, the phase is inverted by the reflector 61 to become clockwise circularly polarized light.

The clockwise circularly polarized light whose phase has been inverted by the reflector 61 changes from circularly polarized light to elliptically polarized light when passing through the liquid crystal 21 of the liquid crystal layer. In the polarization state, the light reaches the reflective display electrode 50, is reflected, and the phase is inverted. Thereafter, the light again passes through the liquid crystal 21 of the liquid crystal layer to become counterclockwise circularly polarized light, reaches the retardation plate 43, becomes linearly polarized light vibrating in the same direction as the transmission axis of the polarizing plate 44, and transmits to the outside. .

In the above description, the direction of circularly polarized light has been described with respect to the traveling direction of light. Further, in the above description of the case of using the reflection type, the case where clockwise circularly polarized light is obtained by the phase difference plate 43 is shown. However, the direction of circularly polarized light after being reflected by the reflector 61 and the position of the reflection type are considered. If the direction of circularly polarized light after passing through the phase difference plate 43 is set to be the same, the case of counterclockwise circularly polarized light may be used.

As described above, the polarization state of light reaching the reflective display electrode 50 when used as a reflective liquid crystal display device is the same as the polarization state of light reaching the reflective display electrode 50 when used as a transmissive liquid crystal display device. Therefore, one liquid crystal display device can have both the reflection type and the transmission type functions.

The reflective display electrode 50 is connected to the TFT substrate 10.
Is provided on the liquid crystal layer 21 side, so that even when used as a reflection type, it is possible to suppress the occurrence of parallax due to the thickness of the glass substrate as in the related art, and to display pixels of a certain color. In addition to suppressing color bleeding in the case of color display due to transmitted light passing through and radiating adjacent display pixels, it also provides contrast due to white and black bleeding of adjacent display pixels in the case of monochrome display. Can be suppressed from decreasing.

Further, the TFT substrate 10 and the counter electrode substrate 30
Can be held by the spacer 70, so that there is no need to disperse a columnar spacer over the entire surface of the substrate as in the related art, and the gap can be reliably held.

In this embodiment, polycrystalline silicon is used as the active layer of the TFT. However, the present invention is not limited to this. The effects of the invention are exhibited.

Further, in the present invention, a conductive reflective material other than Al and silver may be used as the reflective display electrode material.

Further, in the present embodiment, the window 60 provided in the reflective display electrode 50 is provided substantially at the center of the reflective display electrode 50, but need not always be located at the center.

Further, in the present embodiment, the case where the spacer 70 is provided on the TFT substrate 10 side has been described, but it may be formed on the counter electrode substrate 30 side. That is,
After the reflector 61 is formed, a photo-curable resist, which is an acrylic resin, is applied to the entire surface of the counter electrode substrate 30 by using a spinner or the like, and then light is applied using a mask that leaves the resist at a position corresponding to the reflector 61 May be irradiated and cured to form the spacer 70 at a position corresponding to the reflector 61. The thickness of the spacer 70 depends on the thickness of the TFT 61 from the reflector 61.
It is set according to the interval between the protective films 33 provided on the substrate 10. After the spacer 70 is thus formed, an alignment film 20 made of polyimide or the like and aligning the liquid crystal 21 is formed.

[0048]

According to the present invention, it is possible to obtain a liquid crystal display device having no color fringing in the case of color display because no parallax is generated, and a liquid crystal display device having both reflection and transmission functions. .

[Brief description of the drawings]

FIG. 1 is a plan view of a reflective and transmissive integrated liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view of the reflective and transmissive integrated liquid crystal display device of the present invention, taken along line AA in FIG.

FIG. 3 is a cross-sectional view of the reflective and transmissive integrated liquid crystal display device of the present invention, taken along line BB in FIG.

FIG. 4 is a cross-sectional view of a conventional reflective and transmissive integrated liquid crystal display device corresponding to line AA in FIG.

FIG. 5 is a cross-sectional view of a conventional integrated reflection and transmission type liquid crystal display device corresponding to line BB in FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 TFT substrate 13 Active layer 15 Interlayer insulating film 16 Drain electrode 17 Flattening insulating film 19 Transparent electrode 21 Liquid crystal 30 Counter electrode substrate 31 Color filter 22, 43 Phase difference plate 23, 44 Polarizing plate 50 Reflective display electrode 60 Window 61 Reflector 70 Spacer G Gate signal line D Drain signal line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA11X FA11Z FD06 FD09 FD15 FD21 GA13 KA02 LA03 LA30 2H092 HA05 JA26 JA29 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB42 JB54 JB56 JB63 JB69 KA04 KA07 KB25 KB

Claims (2)

[Claims] A plurality of gate signal lines and a plurality of drain signal lines, each of which includes a display pixel region arranged in a matrix shape so as to intersect each other and intersect with each other; Comprising a reflective display electrode made of a reflective material in the display pixel region,
A first substrate having a window made of a transparent conductive material that transmits light in a part of each of the reflective display electrodes, and a counter electrode made of a transparent conductive material provided to face each of the reflective display electrodes;
And a second substrate provided with a reflector for reflecting light incident from the first substrate side to the first substrate side at a position corresponding to each of the windows, wherein a positive dielectric anisotropy is provided. And a spacer made of a material that does not cause a phase difference of light incident from the first substrate side is disposed between the reflector and the window. A polarizing plate and a retardation plate are provided on the side of the second substrate not filled with the liquid crystal, respectively.
A liquid crystal display device arranged to generate circularly polarized light in the same direction as viewed from the substrate side. 2. The liquid crystal display device according to claim 1, wherein the material that does not cause the phase difference is an acrylic resin.