JP2003344875A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein a polarization state of reflected light going and returning through a liquid crystal in a reflection region and a polarization state of transmitted light passed through a hole for passing light can coincide with each other without conventionally enlarging the height of a structure. <P>SOLUTION: A gate wiring 1 and a source wiring 2 are disposed so as to cross each other and a thin film transistor 5 is provided on a transparent substrate 15. As the other member, a color filter 16, a transparent electrode 13 consisting of ITO or the like and an alignment layer are formed on a counter substrate 14 and a transparent synthetic resin layer 17 is formed at the part corresponding to a transmission mode on the color filter 16 having a flat shape. Optical retardation of a liquid crystal layer in the reflection region is specified to be 90°×(2m-1), wherein m=1, 2, 3,..., and optical retardation of the liquid crystal layer in a transmission region is specified to be 180°×(2n-1), wherein n=1, 2, 3,.... <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used not only for small or medium-sized portable information terminals and notebook computers, but also for large and high-definition monitors. Furthermore, the technology of a reflective liquid crystal display device that does not use a backlight has been developed, and is excellent in thinness, light weight, and low power consumption.

The reflection type liquid crystal display device is of a scattering reflection type in which an uneven light reflection layer is formed on the inner surface of a substrate arranged in the rear, but it is possible to effectively use ambient light by not using a backlight. We are using.

Also, a transflective liquid crystal display device has been developed in which a transflective film is formed in place of the light reflection layer, a backlight is provided, and a reflective mode or a transmissive mode is selectively used.

According to this semi-transmissive liquid crystal display device, it is used as a reflective device by external illumination such as sunlight or a fluorescent lamp, or as a transmissive device by mounting a backlight as internal illumination. , A semi-permeable membrane is used to have both functions (Japanese Patent Laid-Open No. 8-
292413 and JP-A-7-318929).

Also, a semi-transmissive liquid crystal display device is realized by allowing a part of light to pass through the light-transmitting hole and reflecting a part of the light by means of the reflecting film provided with the light-transmitting hole. A configuration is also proposed (Patent No. 28782).
31 and JP-A-2000-19563).

Further, in the reflection film structure provided with the light transmitting hole, in order to match the optical path length of the reflected light traveling back and forth in the liquid crystal in the reflection area with the optical path length of the transmitted light passing through the light passing hole, A technique has also been proposed in which the cell gap of the liquid crystal in the reflective region is made half the cell gap of the liquid crystal in the transmissive region. (See JP-A-11-101992).

[0008]

However, in order to reduce the cell gap of the liquid crystal in the reflective region to 1/2 of the cell gap of the liquid crystal in the transmissive region, the liquid crystal layer has a cell gap of 1 / g of the cell gap.
It is necessary to form a structure corresponding to the film thickness of 2. Therefore, when a large structure is made, the rubbing process becomes unstable, and as a result, the large structure cannot be formed and the height of the structure increases. The cell gap in the transmissive region is twice as large as the cell gap in the transmissive region.

The present invention has been completed in view of the above circumstances, and an object thereof is to increase the height of a structure by optimizing the ratio of the cell gap between the reflective region and the transmissive region, thereby increasing the reflective region. Even if the thickness of the liquid crystal layer of is not remarkably reduced, the polarization state of the reflected light traveling back and forth in the liquid crystal in the reflection area and the polarization state of the transmitted light passing through the light passage hole can be made to coincide with each other. An object of the present invention is to provide a liquid crystal display device in which the cell gap can be increased and which is extremely easy to manufacture.

[0010]

In the liquid crystal display device of the present invention, a plurality of source wirings and a plurality of gate wirings are formed on a substrate so as to intersect with each other, and the respective intersections of the source wirings and the gate wirings are formed. In the form of a matrix, corresponding to each intersection, a pixel electrode and a switching element for supplying an image signal to each pixel electrode are formed respectively, and one member formed by further coating an alignment film on these pixel electrodes, The counter electrode provided on the other substrate so as to face the pixel electrode and the other member having the alignment film formed thereon are disposed so as to face each other with the liquid crystal layer interposed therebetween, and the pixel electrode is a laminate of a transparent electrode and a metal layer. Yes, there is no reflection mode corresponding to the deposition area of the metal layer, no transmission mode corresponding to the area without the metal layer, and the phase difference of the liquid crystal layer with respect to visible light of the liquid crystal layer used in the reflection mode. 90 ° x (2m-1 ) (However, m = 1, 2, 3, ...
.) Is 180 ° × (2n−1) (where n is the phase difference of the liquid crystal layer for visible light of the liquid crystal layer used in the transmission mode).
= 1, 2, 3 ...).

Another liquid crystal display device of the present invention is characterized in that a transparent synthetic resin layer is formed on a portion of the other member on the substrate corresponding to the transmission mode.

In still another liquid crystal display device of the present invention, a color filter is formed on the substrate of the other member, and a transparent synthetic resin layer is formed on a portion of the color filter corresponding to the transmission mode. And

In still another liquid crystal display device of the present invention, a color filter is formed on the substrate of the other member, and the layer thickness of the portion corresponding to the transmission mode of the color filter is changed to the layer thickness of the portion corresponding to the reflection mode. It is characterized in that it is made larger than the thickness.

Further, the liquid crystal display device of the present invention is characterized in that a light scattering layer is formed on a portion of the other member corresponding to the reflection mode.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) This embodiment will be described below with reference to the drawings.

FIG. 1 is a plan view of a main part of an active matrix substrate in the liquid crystal display device of this embodiment, and FIG. 2 is a cross-sectional view taken along the line AA 'of the liquid crystal display device shown in FIG.

In this example, 1 is a gate wiring, 2 is a source wiring, 3 is an upper layer pixel electrode, 4 is a lower layer pixel electrode, 5 is a thin film transistor, 11 is a protective film, 12 is a liquid crystal material, 13 is
Is a counter electrode, and 14 and 15 are transparent substrates made of glass or plastic.

Regarding the one member, a plurality of gate wirings 1 and a plurality of source wirings 2 are arranged on the transparent substrate 15 so as to intersect (orthogonal), and a portion surrounded by these wirings is a pixel. The thin film transistor 5, which is the switching element, is provided at the intersection of the wirings.

As is well known in the art, the thin film transistor 5 is composed of a gate insulating film 8, a semiconductor layer 9, an n ⁺ -Si layer 10, a source electrode 6 and a drain electrode 7 on the gate wiring 1.

The gate wiring 1 is made of Ta, Al, Al alloy (Al
It is formed of a metal thin film such as Ta or AlNd). The gate insulating film 8 is made of Ta ₂ O ₃ , SiN _x, or the like. The semiconductor film 9 is made of Si. Source electrode 6 and drain electrode 7
Is formed of a metal film of Al, Al alloy (AlTa, AlNd) or the like, and is connected to a transparent electrode made of ITO.

Although not shown, an alignment film is applied on the active matrix substrate having the above structure.

According to the other member, a color filter 16, a transparent electrode 13 made of ITO or the like, and an alignment film (not shown) are formed on the counter substrate 14. The liquid crystal 12 is injected between the substrates to obtain the liquid crystal display device of this example.

The pixel electrode includes the upper pixel electrode 3 which is the transparent electrode (for example, made of ITO) and the metal layer (for example, Al, Al alloy (AlTa, AlNd)).
Etc.) and the lower layer pixel electrode 4 is combined with the lower layer pixel electrode 4 to form a reflection mode, and a region without the lower layer pixel electrode 4 corresponds to a transmission mode.

According to the present invention, as shown in FIG. 2, the transparent synthetic resin layer 17 is formed on the flat color filter 16 at a portion corresponding to the transmission mode. The synthetic resin layer 17 is made of, for example, Nippon Steel Chemical's acrylic transparent resin (PHA-094X).

Here, the structure of the transparent resin layer 17 having a height of 1.5 μm causes Δnd of the reflection area.
(Product of Δn of liquid crystal and cell gap d) is 0.413 μm
(Δn = 0.092, cell gap = 4.5 μm), Δnd (product of Δn of liquid crystal and cell gap d) of the transmission region is 0.275 μm (Δn = 0.092, cell gap = 3) .0
μm), The twist angle of the liquid crystal molecules of the liquid crystal display device is 0 ° (that is, the twist angle is 0 °, and the liquid crystal molecules are aligned in parallel between the upper and lower glass substrates).

At this time, when visible light passes through the reflection area,
When the phase shifts by 270 ° and visible light passes through the transmission area,
180 ° out of phase. The polarization states of the reflected light and the transmitted light at this time will be described with reference to FIGS. 8 and 9. Figure 8
FIG. 9 is a schematic diagram showing the polarization state during black display, and FIG. 9 is a schematic diagram showing the polarization state during white display.

Reference numeral 19 denotes a circularly polarizing plate (λ / 4). A reflective film 20 is provided inside the two circularly polarizing plates (λ / 4), and a reflection mode is set corresponding to the adhered area. Synthetic resin layer 17
The transmission mode is set according to the laminated structure of the pixel electrode 21 and the pixel electrode 21. Then, the polarizing plate 18 is arranged outside each circular polarizing plate (λ / 4) 19.

FIG. 8 shows the polarization state when an electric field is applied to the liquid crystal and the liquid crystal molecules stand vertically.

Ambient light incident on the reflection area is randomly polarized, but by passing through the upper polarizing plate 18,
It becomes linearly polarized light in the same direction as the transmission axis of the upper polarizing plate 18.
Further, it passes through the upper circularly polarizing plate 19 to become left circularly polarized light. Since the liquid crystal molecules are in an upright state, the liquid crystal layer has almost no phase difference and reaches the reflection film 20 as left circularly polarized light. The left circularly polarized light is changed to the right circularly polarized light by the reflection film 20, and the liquid crystal layer is emitted in the state of the right circularly polarized light.
Further, when it passes through the upper circular polarization plate 19, it becomes linearly polarized light'in a direction perpendicular to the transmission axis of the upper polarization plate 18, and all is absorbed by the upper polarization plate 18.

Random polarized light is incident on the transmission region, but when it passes through the lower polarizing plate 18, it becomes linearly polarized light in the same direction as the transmission axis of the lower polarizing plate 18. Further, by passing through the lower circularly polarizing plate 19, it becomes right circularly polarized light and enters the liquid crystal layer. And since the liquid crystal molecules are in a standing state, there is almost no phase difference in the liquid crystal layer,
Leaves the liquid crystal layer as right circularly polarized light. Circular polarizing plate 1 on the upper side
After passing through 8, the light becomes linearly polarized light'in a direction perpendicular to the transmission axis of the upper polarizing plate 18, and all is absorbed by the upper polarizing plate 18.

As described above, for black display, the reflected light
Both'and transmitted light 'have the same polarization state.

FIG. 9 shows the polarization state when the liquid crystal molecules are aligned at a twist angle of 0 ° because no electric field is applied to the liquid crystals.

Ambient light incident on the reflection area is randomly polarized, but by passing through the upper polarizing plate 18,
It becomes linearly polarized light in the same direction as the transmission axis of the upper polarizing plate 18.
Further, it passes through the upper circularly polarizing plate 19 to become left circularly polarized light. Since the liquid crystal molecules are aligned at a twist angle of 0 °, the liquid crystal layer is out of phase by 270 °. Here, the liquid crystal layer will be described in three stages for each 90 ° phase shift.

First, in the liquid crystal layer having a 90 ° phase shift, the left circularly polarized incident light becomes linearly polarized light in the direction perpendicular to the transmission axis of the upper polarizing plate 18, and the next 90 ° phase shift liquid crystal. In the layer, linearly polarized light perpendicular to the transmission axis of the upper polarizing plate 18 becomes right circularly polarized light, and in the liquid crystal layer having a final phase shift of 90 °, the right circularly polarized light has the same direction as the transmission axis of the upper polarizing plate 18. The light reaches the reflection film 20 in a linearly polarized state. The reflection film 20 reflects the same linearly polarized light and leaves the liquid crystal layer in the left circularly polarized state by the same principle. Further, by passing through the upper circular polarization plate 19, it becomes linearly polarized light'in the same direction as the transmission axis of the upper polarization plate 18, and the upper polarization plate 18
All pass through.

Random polarized light is incident on the transmission region, but when it passes through the lower polarizing plate 18, it becomes linearly polarized light in the same direction as the transmission axis of the lower polarizing plate 18. Further, by passing through the lower circularly polarizing plate 18, it becomes right circularly polarized light. Since the liquid crystal molecules are aligned at a twist angle of 0 °, the liquid crystal layer is out of phase by 180 °.
Here, the liquid crystal layer will be described in two stages for each 90 ° phase shift.

First, in the liquid crystal layer having the first phase shift of 90 °, the right circularly polarized incident light becomes linearly polarized light in the direction perpendicular to the transmission axis of the upper polarization plate 18, and the liquid crystal having the next phase shift of 90 °. In the layer, the liquid crystal layer exits from the linearly polarized light in the direction perpendicular to the transmission axis of the upper polarizing plate 18 to the left circularly polarized light. Further, by passing through the upper circular polarization plate 19, the upper polarization plate 1
It becomes linearly polarized light in the same direction as the transmission axis of 8. further,
By passing through the upper polarizing plate 18, the upper polarizing plate 1
8 linearly polarized light in the same direction as the transmission axis is obtained.

As described above, the reflected light is also displayed in the white display.
Since the polarization states of "and transmitted light" are the same, "
The light is not absorbed between ", and the decrease in the brightness of the white display of the transmitted light is not remarkable.

That is, the phase difference of the liquid crystal layer in the reflection area is set to 9
0 ° × (2m−1), where m = 1, 2, 3 ...
The phase difference of the liquid crystal layer in the transmission region is 180 ° × (2n−1),
However, by setting n = 1, 2, 3, ..., Absorption of white display during transmission does not occur.

Regarding the above phenomenon, a normally white mode in which a polarizing plate and a circularly polarizing plate are installed before and after the liquid crystal layer and white display is performed when the liquid crystal layer has no electric field is described.

On the other hand, as shown in FIGS. 20 and 21, only polarizing plates are provided before and after the liquid crystal layer (only polarizing plates are provided above and below in these figures), and the liquid crystal layer displays black when no electric field is applied. Similarly, in the case of polarized light in the normally black mode, the retardation of the liquid crystal layer in the reflective region is 90 ° ×
(2m-1) m = 1, 2, 3 ..., 180 ° × (2n−1) n = 1, 2, 3
.., the polarization states at the time of transmission and at the time of reflection become equal.

Next, with reference to FIG. 4, a method of forming the upper substrate (other substrate) of this embodiment will be described. As shown in FIG. 4, steps 1 to 4 are sequentially performed.

(Step 1) According to this step, the glass substrate 1
A Cr layer is formed with a film thickness of 2000 Å or a resin in which a black pigment is dispersed is formed with a film thickness of 1 μm at a position corresponding to between pixels on the surface 4, and thereby the light shielding film 22 is formed.

(Step 2) Using a photolithography technique, a resin having a red pigment dispersed therein has a thickness of 1 μm, a resin having a green pigment dispersed therein has a thickness of 1 μm, and a resin having a blue pigment dispersed therein has a thickness of 1 μm. The color filter 16 is formed to have a film thickness.

(Step 3) Color filter 1 having a flat shape
A synthetic resin layer 17 having a film thickness of 1.5 .mu.m is formed on the region 6 corresponding to the transmission mode.

(Step 4) The transparent electrode 13 (IT
O film) is formed with a film thickness of 1400Å.

For reference, as in the conventional liquid crystal display device, when the liquid crystal layers in the reflective region and the transmissive region have the same thickness, that is, when the liquid crystal layers in the reflective region and the transmissive region have the same birefringence, the reflected light is the same. The polarization state of transmitted light will be described with reference to FIGS. 6 and 7.

FIG. 6 shows the polarization state when an electric field is applied to the liquid crystal and the liquid crystal molecules are standing vertically.

Ambient light incident on the reflection area is randomly polarized, but by passing through the upper polarizing plate 18,
It becomes linearly polarized light in the same direction as the transmission axis of the upper polarizing plate 18.
Further, it passes through the upper circularly polarizing plate 19 to become left circularly polarized light. Further, since the liquid crystal molecules are in an upright state, there is almost no phase difference in the liquid crystal layer, and the liquid crystal molecules reach the reflection film 20 as left circularly polarized light. The left circularly polarized light is changed to the right circularly polarized light by the reflection film 20, and the liquid crystal layer exits in the state of the right circularly polarized light. Further, by passing through the upper circular polarization plate 18, it becomes linearly polarized light'in a direction perpendicular to the transmission axis of the upper polarization plate 18, and all is absorbed by the upper polarization plate 18.

Random polarized light is incident on the transmission region, but when it passes through the lower polarizing plate 18, it becomes linearly polarized light in the same direction as the transmission axis of the lower polarizing plate 18. Further, by passing through the lower circularly polarizing plate 18, it becomes right circularly polarized light. And since the liquid crystal molecules are in a standing state,
The liquid crystal layer has almost no phase difference and exits the liquid crystal layer as right circularly polarized light. Further, by passing through the upper circular polarization plate 18, linearly polarized light in a direction perpendicular to the transmission axis of the upper polarization plate 18 is obtained.
', And all are absorbed by the upper polarizing plate.

As described above, for black display, the reflected light
Both'and transmitted light 'have the same polarization state.

In FIG. 7, no electric field is applied to the liquid crystal, and the liquid crystal molecules show a polarization state when the liquid crystal molecules are aligned at a twist angle of 0 °.

Ambient light incident on the reflection area is randomly polarized, but by passing through the upper polarizing plate 18,
It becomes linearly polarized light in the same direction as the transmission axis of the upper polarizing plate 18.
Further, it passes through the upper circularly polarizing plate 19 to become left circularly polarized light. Since the liquid crystal molecules are aligned at a twist angle of 0 °, the liquid crystal layer is out of phase by 90 °, and is linearly polarized in a direction perpendicular to the transmission axis of the upper polarizing plate 18,
The reflection film 20 is reached. The reflection film 20 reflects the same linearly polarized light and leaves the liquid crystal layer in the state of left circularly polarized light. further,
By passing through the upper circularly polarizing plate 19, it becomes linearly polarized light'in the same direction as the transmission axis of the upper polarizing plate 18, and it passes through all of the upper polarizing plate 18, and becomes ".

Random polarized light is incident on the transmission region, but when it passes through the lower polarizing plate 18, it becomes linearly polarized light in the same direction as the transmission axis of the lower polarizing plate 18. Further, it passes through the lower circularly polarizing plate 19 to become right circularly polarized light. Since the liquid crystal molecules are aligned at a twist angle of 0 °, the liquid crystal layer is out of phase by 90 ° and becomes linearly polarized light in a direction perpendicular to the transmission axis of the lower polarizing plate 18 and exits the liquid crystal layer. Further, by passing through the upper circularly polarizing plate 19, it becomes left circularly polarized light '. Further, by passing through the upper polarization plate 18, linearly polarized light in the same direction as the transmission axis of the upper polarization plate 18 is obtained.

As described above, for white display, the reflected light
Since the polarization states of'and transmitted light 'are different,
Part of the light is absorbed by the upper polarization plate 18 during the period "," which causes a reduction in the brightness of the white display of the transmitted light.

Regarding such a conventional liquid crystal display device, as shown in the sectional view of the essential part of FIG.
This is a liquid crystal display device proposed in No. 01992.

According to the conventional technique, the thickness of the liquid crystal layer in the reflective region is half the thickness of the liquid crystal layer in the transmissive region, but the structure is very large in the reflective region and the transmissive region with respect to the thickness of the liquid crystal layer. However, there is a problem that the film thickness of the liquid crystal layer in the reflection region becomes very small, which is difficult in manufacturing.

On the other hand, in the present invention, according to steps 1 to 4 shown in FIG. 4, the step between the reflection area and the transmission area can be reduced, and the thickness of the liquid crystal layer in the reflection area can be reduced. It can be made larger and easier to manufacture.

(Embodiment 2) FIG. 1 is a plan view of a main portion of an active matrix substrate in a liquid crystal display device of this embodiment, and FIG. 3 is a sectional view taken along the line AA ′ of FIG. The same parts as those of the liquid crystal display device of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals.

As shown in FIG. 3, the color filter 16 is formed on the substrate of the other member, and the layer thickness of the portion corresponding to the transmission mode of this color filter 16 is compared with the layer thickness of the portion corresponding to the reflection mode. Then, the transparent electrode 13 (ITO) is formed on the color filter 16 having such a structure.
Forming a film).

Here, due to the step structure constituted by the film thickness difference (1.5 μm) of the color filter 16 in the reflective area and the transmissive area, the product of Δnd (Δn of liquid crystal and cell gap d) of the reflective area. ) Is 0.413 μm (△ n = 0.09
2, cell gap = 4.5 μm), and Δnd of transmission area
(Product of liquid crystal Δn and cell gap d) is 0.275 μm
(Δn = 0.092, cell gap = 3.0 μm). The twist angle of the liquid crystal molecules of the liquid crystal display device is 0.
°.

At this time, when visible light passes through the reflection area,
When the phase shifts by 270 ° and visible light passes through the transmission area,
The phases are shifted by 180 °, the polarization states of reflected light and transmitted light are the same when an electric field is applied to the liquid crystal and when no electric field is applied, resulting in high light utilization efficiency.

Next, with reference to FIG. 5, a method of forming the upper substrate (other substrate) of this embodiment will be described. As shown in FIG. 5, steps 1 to 4 are sequentially performed.

(Step 1) The light-shielding film 22 is formed on the glass substrate 14 at positions corresponding to pixels. This film 22 is C
The r layer is formed to a film thickness of 2000Å, or the resin in which the black pigment is dispersed is formed to a film thickness of 1 μm.

(Step 2) A resin in which a red pigment is dispersed is applied to the substrate 14 in a film thickness of 3 μm, and a predetermined pattern is formed by a photolithography technique.

A photo mask 24 is used for this, and a Cr light shielding film 23 is patterned on this, and U
V exposure 25 is performed. The light shielding film 23 is not formed in the portion corresponding to the transmissive region of the substrate 14, and the light shielding film 23 is formed in a slit shape in the portion corresponding to the reflective region.

(Step 3) In this step, the substrate in the previous step is developed, so that the film thickness of the portion corresponding to the reflective portion is 1.
A color filter 16 having a thickness of 5 μm and a film thickness of a portion corresponding to the transmitting portion of 3.0 μm can be obtained. Similarly, a resin in which a green pigment is dispersed and a resin in which a blue pigment is dispersed are also formed.

(Step 4) The transparent electrode 13 (ITO film) is formed on the color filter 16 to a film thickness of 1400Å.

Also in this example, the step between the reflective region and the transmissive region can be reduced and the film thickness of the liquid crystal layer in the reflective region can be increased, which facilitates the manufacture.

(Embodiment 3) FIG. 10 is a plan view of a main portion of an active matrix substrate in a liquid crystal display device of this embodiment, and FIG. 12 is a sectional view taken along line AA ′ of FIG. The same parts as those of the liquid crystal display device of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals.

In FIG. 12, the structure of the lower substrate, which is one member, is the transparent electrode ITO connected to the drain electrode.
Is connected to the upper metal reflective electrode via an acrylic resin. Here, the electrode in the portion corresponding to the reflective region is arranged on the upper surface of the acrylic resin 17, and the acrylic resin 17 is not formed in the portion corresponding to the transmissive region, so that a step is formed between the reflective region and the transmissive region. It is provided.

According to this example, one member was coated with the acrylic resin 17 having a film thickness of 1.0 μm, so that Δnd (the product of Δn of the liquid crystal and the cell gap d) of the reflective region was reduced to 0.0. 690 μm (Δn = 0.138, cell gap = 5.0
μm), and Δnd (product of Δn of liquid crystal and cell gap d) in the transmission region is 0.828 μm (Δn = 0.138, cell gap = 6.0 μm). Here, the twist angle of the liquid crystal molecules of the liquid crystal display device is 0 °.

Thus, according to the liquid crystal display device of this example, when visible light passes through the reflection area, the phase shifts by 450 °, and when visible light passes through the transmission area, the phase shifts by 540 °, and an electric field is applied to the liquid crystal. The polarization state of the reflected light is the same as that of the transmitted light both when there is no electric field, and the light utilization efficiency is high.

(Embodiment 4) This embodiment will be described with reference to FIGS. 13 and 14. 13 is a plan view of a main part of the active matrix substrate in the liquid crystal display device of this example, and FIG. 14 is a cross-sectional view taken along the line AA ′ in FIG. In addition,
The same parts as those of the liquid crystal display device according to the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals.

The liquid crystal display device of this example is characterized in that the light scattering layer 17 is formed in the reflection region of the other member.

The light-scattering layer 17 is made of transparent resin containing scattering particles such as silica having different refractive indexes, which is the same as forming a scattering layer such as a forward scattering film above the panel. It has various functions.

By forming the light scattering layer 17 as described above only in the portion corresponding to the reflection area, a step between the reflection area and the transmission area is formed.

According to the liquid crystal display device having such a structure,
Since the thickness of the light-scattering layer 17 is 1.0 μm, Δnd (product of Δn of liquid crystal and cell gap d) in the reflective region is set to be 0.0.
690 μm (△ n = 0.138, cell gap = 5.0μ
m), Δnd of the transmissive region (Δn of liquid crystal and cell gap d
The product) is 0.828 μm (Δn = 0.138, cell gap = 6.0 μm). The twist angle of the liquid crystal molecules of the liquid crystal display device is 0 °.

Thus, according to the liquid crystal display device of the present invention,
When visible light passes through the reflection area, the phase shifts by 450 °,
When visible light passes through the transmission area, the phase shifts by 540 °,
The reflected light and the transmitted light have the same polarization state both when an electric field is applied to the liquid crystal and when no electric field is applied, and the light utilization efficiency is improved.

Next, a method of forming the other member of this example will be described with reference to FIG. As shown in FIG. 17, step 1 is sequentially performed.
~ Go through step 4.

(Step 1) The light-shielding film 22 is formed on the glass substrate 14 at positions corresponding to pixels. This film 22 is C
The r layer is formed to a film thickness of 2000Å, or the resin in which the black pigment is dispersed is formed to a film thickness of 1 μm.

(Step 2) Using a photolithographic technique, a resin in which a red pigment is dispersed is formed in a film thickness of 1 μm, a resin in which a green pigment is dispersed is formed in a film thickness of 1 μm, and a resin in which a blue pigment is dispersed is formed on a substrate. The color filter 16 is provided with a film thickness of 1 μm.

(Step 3) Using the photolithography technique, the light scattering layer 17 is formed with a thickness of 1 μm on the color filter 16 at the portion corresponding to the reflection region.

(Step 4) The transparent electrode 13 (I
A TO film) is formed with a film thickness of 1400Å.

(Fifth Embodiment) This embodiment will be described with reference to FIGS. 13 and 15. FIG. 13 is a plan view of a main part of an active matrix substrate in the liquid crystal display device of this example.
FIG. 14 is a sectional view taken along the line AA ′ of FIG. 13. 1 and 2
The same parts as those of the liquid crystal display device according to the first embodiment shown in FIG.

The liquid crystal display device of this example is also characterized in that the light scattering layer 17 is formed in the reflection region of the other member, but the light scattering layer 17 is provided directly on the substrate 14. The light-scattering layer 17 is also made of transparent resin containing scattering particles such as silica having different refractive indexes, and has the same function as forming a scattering layer such as a forward scattering film above the panel.

By forming the light-scattering layer 17 as described above only in the portion corresponding to the reflection area, a step between the reflection area and the transmission area is formed.

According to this example, when the light scattering layer 17 is formed on the portion corresponding to the reflection area and the color filter 16 is deposited thereon, the film thickness at the portion corresponding to the transmission area is It is formed twice as thick as the film thickness of the portion corresponding to the region, and the color purity of the reflection mode and the transmission mode is made equal in the display of the liquid crystal display device.

Here, the light scattering layer 17 and the color filter 1
When the thickness is 1.0 μm by stacking with No. 6, Δnd (product of Δn of liquid crystal and cell gap d) of the reflective region is 0.0.
690 μm (△ n = 0.138, cell gap = 5.0μ
m), Δnd of the transmissive region (Δn of liquid crystal and cell gap d
The product) is 0.828 μm (Δn = 0.138, cell gap = 6.0 μm). The twist angle of the liquid crystal molecules of the liquid crystal display device is 0 °.

At this time, when visible light passes through the reflection area,
When the phase shifts 450 ° and visible light passes through the transmission area,
The phase is shifted by 540 °, and the polarization states of the reflected light and the transmitted light are the same when the electric field is applied to the liquid crystal and when the electric field is not applied, and the light utilization efficiency is high.

Next, a method for producing the other member of this example will be described with reference to FIG. As shown in FIG. 18, step 1 is sequentially performed
~ Go through step 4.

(Step 1) The light shielding film 22 is formed on the glass substrate 14 at positions corresponding to the pixels. This film 22 is C
The r layer is formed to a film thickness of 2000Å, or the resin in which the black pigment is dispersed is formed to a film thickness of 1 μm.

(Step 2) Using the photolithography technique, the light scattering layer 17 is applied to the portion corresponding to the reflection area on the substrate 14.
Is formed with a film thickness of 2.0 μm.

(Step 3) On the light-scattering layer 17, a resin in which a red pigment is dispersed is formed with a film thickness of 1 μm in a portion corresponding to the reflection area by using a photolithography technique. However, since the portion corresponding to the transmissive region is depressed, it is formed with a film thickness of 2 μm.

Similarly, a resin in which a green pigment is dispersed and a resin in which a blue pigment is dispersed are also formed and the color filter 16 is attached.

(Step 4) The transparent electrode 13 (I
A TO film) is formed with a film thickness of 1400Å.

(Sixth Embodiment) This embodiment will be described with reference to FIGS. 13 and 16. FIG. 13 is a plan view of a main part of the active matrix substrate in the liquid crystal display device of this example.
FIG. 14 is a sectional view taken along the line AA ′ of FIG. 13. 1 and 2
The same parts as those of the liquid crystal display device according to the first embodiment shown in FIG.

The liquid crystal display device of this example is also characterized in that the light scattering layer 17 is formed in the reflection region of the other member, but a portion where the color filter 16 is not formed is formed on the substrate 14. Thereby, in the display of the liquid crystal display device, the color purities of the reflection mode and the transmission mode are made equal to each other.

The light-scattering layer 17 as described above is also one in which scattering particles such as silica having different refractive indexes are put in a transparent resin, and a scattering layer such as a forward scattering film is formed above the panel. It has the same function. Then, by forming the light scattering layer 17 as described above only in the portion corresponding to the reflective region, a step between the reflective region and the transmissive region is formed.

According to this example, the laminated thickness of the light scattering layer 17 and the color filter 16 is set to 1.0 μm,
Δnd (product of liquid crystal Δn and cell gap d) of the reflection area is 0.690 μm (Δn = 0.138, cell gap =
5.0 μm), and Δnd (product of liquid crystal Δn and cell gap d) of the transmission region is 0.828 μm (Δn = 0.138,
The cell gap is 6.0 μm. The twist angle of the liquid crystal molecules of the liquid crystal display device is 0 °.

Thus, according to the present invention, when visible light passes through the reflection region, the phase shifts by 450 °, when visible light passes through the transmission region, the phase shifts by 540 °, and no electric field is applied even when an electric field is applied to the liquid crystal. Even at this time, the polarization states of the reflected light and the transmitted light are equal, and the light utilization efficiency is high.

Next, a method of forming the other member of this example will be described with reference to FIG. As shown in FIG. 19, step 1 is sequentially performed
~ Go through step 4.

(Step 1) A light-shielding film 22 is formed on the glass substrate 14 at positions corresponding to pixels. This film 22 is C
The r layer is formed to a film thickness of 2000Å, or the resin in which the black pigment is dispersed is formed to a film thickness of 1 μm.

(Step 2) Using a photolithographic technique, a resin in which a red pigment is dispersed is formed in a film thickness of 1 μm, a resin in which a green pigment is dispersed is formed in a film thickness of 1 μm, and a resin in which a blue pigment is dispersed is formed on a substrate. The color filter 16 is provided with a film thickness of 1 μm.

(Step 3) Using the photolithography technique, the light scattering layer 17 is formed with a thickness of 1 μm on the portion corresponding to the reflection region on the color filter 16.

(Step 4) The transparent electrode 13 (I
A TO film) is formed with a film thickness of 1400Å.

The present invention is not limited to the above embodiment, and various modifications and improvements may be made without departing from the scope of the present invention. For example, in each of the embodiments 4, 5, and 6, only the transparent resin may be used instead of the light scattering layer 17.

[0107]

As described above, according to the liquid crystal display device of the present invention, as described above, the retardation of the liquid crystal layer for the visible light of the liquid crystal layer used in the reflection mode is 90 ° × (2m−1).
(Where m = 1, 2, 3 ...), the phase difference of the liquid crystal layer for visible light of the liquid crystal layer used in the transmission mode is 180.
.Degree..times. (2n-1) (where n = 1, 2, 3, ...), and the retardation of the liquid crystal layer for the reflection mode is made larger than that of the liquid crystal layer for the transmission mode. By optimizing the ratio of the cell gap between the reflective area and the transmissive area, and by forming the transparent synthetic resin layer on the part of the other member that corresponds to the transmissive mode, the structure of the conventional structure is improved. It is possible to match the polarization state of the reflected light that travels back and forth through the liquid crystal in the reflection area with the polarization state of the transmitted light that has passed through the light passage hole without increasing the size, and to further increase the cell gap of the liquid crystal. The liquid crystal display device of high quality and high reliability, which can be manufactured easily, can be provided.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of an active matrix substrate in a liquid crystal display device of the present invention.

FIG. 2 is a sectional view A- of the liquid crystal display device shown in FIG.
It is sectional drawing by A '.

FIG. 3 is a sectional view taken along the line AA ′ in FIG. 1 according to the second exemplary embodiment.

4A to 4C are process diagrams showing a method for manufacturing a color filter substrate in the first embodiment.

5A to 5C are process diagrams showing a method of manufacturing a color filter substrate in the second embodiment.

FIG. 6 is a polarization state when displaying black in a conventional liquid crystal display device.

FIG. 7 is a polarization state during white display in a conventional liquid crystal display device.

FIG. 8 is an explanatory diagram showing a polarization state during black display of the liquid crystal display device in the first embodiment.

FIG. 9 is an explanatory diagram showing a polarization state during white display of the liquid crystal display device according to the first embodiment.

FIG. 10 is a plan view of a main portion of an active matrix substrate in another liquid crystal display device of the present invention.

FIG. 11 is a cross-sectional view of a conventional liquid crystal display device.

FIG. 12 is a cross-sectional view taken along the line AA ′ in FIG. 10 according to the third exemplary embodiment.

FIG. 13 is a plan view of a main part of an active matrix substrate in still another liquid crystal display device of the present invention.

FIG. 14 is a cross-sectional view taken along the line AA ′ in FIG. 10 according to the fourth exemplary embodiment.

FIG. 15 is a cross-sectional view taken along the line AA ′ in FIG. 10 according to the fifth exemplary embodiment.

16 is a cross-sectional view taken along the line AA ′ in FIG. 10 according to the sixth exemplary embodiment.

FIG. 17 is a process chart showing the method of manufacturing the color filter substrate in the fourth embodiment.

FIG. 18 is a process drawing showing the manufacturing method of the color filter substrate in the fifth embodiment.

FIG. 19 is a process drawing showing the manufacturing method of the color filter substrate in the sixth embodiment.

FIG. 20 is an explanatory diagram showing a polarization state during white display of the liquid crystal display device during normally black according to the first embodiment.

FIG. 21 is an explanatory diagram showing a polarization state during black display of the liquid crystal display device during normally black in the first embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Gate wiring 2 ... Source wiring 3 ... Upper layer pixel electrode 4 ... Lower layer pixel electrode 5 ... Thin film transistor 6 ... Source electrode 7 ... Drain electrode 8 ... Gate insulating film 9 ... Semiconductor layer 10 ... N ^<+>- Si layer 11 ... Protective film 12 Liquid crystal material 13 Counter electrodes 14, 15 Transparent substrate 16 made of glass or plastic etc. Color filter 17 Light scattering layer 18 Polarizing plate 19 Circular polarizing plate (λ / 4) 20 Reflecting film 21 Transmitting film 22 ... Shading film 23 ... Shading film 24 ... Photomask 25 ... UV light

Claims (5)

[Claims] 1. A plurality of source wirings and a plurality of gate wirings are formed on a substrate so as to intersect with each other, and the respective intersections of the source wirings and the gate wirings are formed in a matrix form. A pixel electrode and a switching element that supplies an image signal to each pixel electrode are formed on each of the pixel electrodes, and one member formed by further covering the pixel electrodes with an alignment film is provided on another substrate facing the pixel electrodes. The opposite electrode and the other member on which the alignment film is formed are arranged opposite to each other with the liquid crystal layer interposed therebetween,
And the pixel electrode is a laminate of a transparent electrode and a metal layer,
In a liquid crystal display device in which a reflection mode is formed corresponding to the area where the metal layer is deposited and a transmission mode is formed when the area without the metal layer is formed, the liquid crystal layer of the liquid crystal layer used in the reflection mode against visible light is used. The phase difference is 90 ° × (2m−1) (where m = 1, 2, 3, ...) And the phase difference of the liquid crystal layer with respect to visible light of the liquid crystal layer used in the transmission mode is 180.
A liquid crystal display device characterized by being defined as ° x (2n-1) (where n = 1, 2, 3 ...). 2. The liquid crystal display device according to claim 1, wherein a transparent synthetic resin layer is formed on a portion of the other member corresponding to the transmission mode on the substrate. 3. A liquid crystal display according to claim 1, wherein a color filter is formed on a substrate of the other member, and a transparent synthetic resin layer is formed on a portion of the color filter corresponding to a transmission mode. apparatus. 4. A color filter is formed on a substrate of the other member, and a layer thickness of a portion corresponding to the transmission mode of the color filter is made larger than a layer thickness of a portion corresponding to the reflection mode. The liquid crystal display device according to claim 1. 5. The liquid crystal display device according to claim 1, wherein a light scattering layer is formed on a portion of the other member corresponding to the reflection mode.