JP3270762B2 - Liquid crystal display - Google Patents

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 and a method of manufacturing the same, and more particularly to a liquid crystal display device having a wide viewing angle and a high speed response, and a method of manufacturing the same.

[0002]

2. Description of the Related Art (First Prior Art) FIGS. 23A and 23B are side sectional views showing the operation of a liquid crystal in a conventional liquid crystal panel.
FIGS. 23C and 23D are front views thereof. In FIG. 23, the active elements are omitted. A plurality of pixels are formed by forming a stripe-shaped electrode. Here, one pixel is shown.

FIG. 23 (a) shows a cross section of the cell side when no voltage is applied.
FIG. 23C shows a front view at that time. Linear electrodes 103 and 104 are formed inside a pair of transparent substrates, and an alignment control film 106 is coated and aligned thereon. A liquid crystal composition is sandwiched between the two. When no voltage is applied, the rod-shaped liquid crystal molecules 105 have a slight angle with respect to the longitudinal direction of the striped Y electrodes, that is, 45 degrees ≦ | φLC | <
90 degrees, (φLC: long axis of liquid crystal molecules near the interface (optical axis)
(The angle between the directions). Here, the liquid crystal molecule alignment directions on the upper and lower interfaces are parallel. The dielectric anisotropy of the liquid crystal composition is assumed to be positive.

Next, when an electric field 109 is applied, FIG.
The liquid crystal changes its direction in the direction of the electric field as shown in (d). By arranging the polarizing plate 102 at the predetermined angle 108, the light transmittance can be changed by applying a voltage. In this way, a display that provides a contrast without a transparent electrode is possible.

However, such a liquid crystal display device of the horizontal electric field type has a unique electrode structure such as a stripe shape as shown in FIG. 23 in addition to a slow response to an electric field of a nematic liquid crystal, and an electric field is applied to the liquid crystal. There is a problem that the response speed is slow because it is difficult to perform.

The rise τri of the liquid crystal in the lateral electric field method
The se and the fall time τ fall are described in JP-A-7-22538.
No. 8 is expressed by the following equation.

[0007] ^{τrise = γ1 / (ε0ΔεE 2 -π} 2 K2 / d 2) ... (1) τfall = γ1d 2 / π 2 K2 = γ1 / ε0ΔεEc 2 ... (2) where, γ1 is viscosity coefficient, K2 is a twist Elastic constant of d
Is the cell gap, Δε is the dielectric anisotropy, ε0 is the dielectric constant of vacuum, E is the electric field strength, and Ec is the threshold electric field.

From the above formulas (1) and (2), in order to make the liquid crystal display device of the in-plane switching method high-speed response, the cell gap d can be reduced or a liquid crystal material having a small viscosity coefficient γ1 and a high dielectric constant (for example, cyano) can be obtained. Or a means for increasing the driving voltage in order to increase the electric field strength E.

(Second Prior Art) FIG.
BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the liquid crystal display device of a horizontal electric field application system disclosed by 236820 gazette. Here, the lateral electric field application method means that both a pixel electrode and a counter electrode are formed on one inner surface of a transparent substrate on the same surface, and a potential is applied between the pixel electrode and the counter electrode formed on these same surfaces. In this method, a lateral electric field in a direction parallel to the plane of the transparent substrate is applied to the liquid crystal to control the arrangement of liquid crystal molecules, thereby improving the viewing angle dependence of the display of the device.

FIG. 24A shows a cross section in a direction perpendicular to a source bus line (video signal line) and in a vertical direction (a direction perpendicular to the substrate surface) of a portion without a semiconductor switching element to be described later. FIG. 24B shows a cross section of a portion where the semiconductor switching element exists, and FIG. 24C shows a cross section of the portion where the semiconductor switching element exists in a direction parallel to the source bus line.

[0011] In FIG.
1b is an upper transparent substrate. 202 is a counter electrode. 203a is a gate electrode. 204 is a source bus line. 205 is a pixel electrode, and 205a is
It is the extension end. 206 is a semiconductor switching element. 207 is a liquid crystal layer. 208a is a lower alignment film, and 208b is an upper alignment film. 209 is a transparent insulating layer.

As shown in FIG. 24, in this liquid crystal display device, two transparent substrates 201a and 201b are arranged facing each other, and liquid crystal is sealed between the facing surfaces via an alignment film. Further, the point that the alignment film is in contact with the upper and lower surfaces of the liquid crystal layer to align the liquid crystal molecules in a predetermined alignment is the same as that conventionally widely used.

However, the alignment film 2 is provided on the array substrate, that is, on the transparent substrate on which the electrodes are to be formed.
08a and the transparent substrate 201a, a transparent insulating layer 209 is disposed, and the transparent insulating layer insulates between the source bus line and the counter electrode and between the source bus line and the pixel electrode, respectively. It is characterized in that the position of the source bus line can be overlapped with the position of the source bus line when viewed from the user of the present apparatus (when the user of the present apparatus looks at the display surface).

This makes it possible to reduce the area of the light-shielding portion generated by the presence of the electrode.
Since the aperture ratio of the pixel portion is increased, the luminance of the entire screen is improved.

[0015]

(Problems of the First Prior Art) However, in the case of the liquid crystal display device of the first conventional example as described above, the following problems remain.

(1) When the cell gap is reduced, the time required for injecting liquid crystal becomes longer and the time required for manufacturing becomes longer. In addition, unevenness due to gap accuracy variation becomes more conspicuous.

(2) When a cyano-based liquid crystal material is used instead of a fluorine-based liquid crystal material or the addition rate is increased, heat and light resistance become unstable, leading to partial abnormalities in contrast and display defects such as flicker. there is a possibility.

(3) Increasing the driving voltage not only increases the power consumption, but also increases the driving I
C cannot be used, and a dedicated driving IC is required.

(4) In order to improve the transmittance, it is necessary to use a transparent electrode such as ITO for the pixel electrode or the common electrode and to improve the response speed, and to form a thicker film. However, if an attempt is made to form such a thick film, the transmittance is reduced due to the deposition of fine crystals, and the film surface is roughened. Therefore, the light scattering value is increased and the light use efficiency is reduced.

(Second Problem of the Prior Art) However,
In the case of the liquid crystal display device of the second conventional example as described above,
The following issues remained.

(1) When the pixel electrode and the counter electrode formed in the pixel portion are non-transmissive conductive layers, light is not transmitted at that portion, and the aperture ratio is reduced. Also, pixel electrodes,
Even if the counter electrode is formed of a transparent conductive layer, the conventional electrode configuration,
In the combination of liquid crystal materials, since the electric field intensity on the electrode is weak, almost no light is transmitted, and therefore, it is not possible to substantially improve the aperture ratio.

(2) If the gate electrode (scanning signal line) and the counter electrode are formed in the same process, the manufacturing process is simplified. However, since the electrodes are close to each other, an electrical short circuit occurs and the yield is increased. May cause a drop.

(3) By providing a counter electrode directly above the source bus line (video signal line), most of the counter electrode and the pixel electrode other than the counter electrode provided immediately above the source bus line (video signal line) are formed. It also affects the distribution of the applied electric field.

(4) The electric field distribution formed by the counter electrode and the pixel electrode immediately above the source bus line (video signal line) is different from the electric field distribution formed by the other counter electrode and the pixel electrode. Alternatively, it is a factor that causes coloring.

The present invention solves the above-mentioned problems and provides a liquid crystal capable of providing a wide viewing angle, high-speed response and high image quality such as high brightness without changing the liquid crystal material, narrowing the cell gap, or increasing the driving voltage. It is an object to provide a display device and a manufacturing method thereof.

[0026]

According to one aspect of the present invention, there is provided an array in which a common electrode, a pixel electrode, a scanning signal line, a video signal line, and a semiconductor switching element are formed. A substrate, a counter substrate, and a liquid crystal layer sandwiched between the array substrate and the counter substrate, and applying a voltage between the pixel electrode and the common electrode to generate an electric field substantially parallel to the substrate. A liquid crystal display device for dimming and driving the liquid crystal, wherein a line width of at least one of the common electrode and the pixel electrode is larger than a gap between the common electrode and the pixel electrode, and The film thickness of at least one of the common electrode and the pixel electrode is larger than the film thickness of at least one of the scanning signal line and the video signal line.

[0027]

[0028]

[0029]

[0030]

When the line width of the electrode is larger than the gap (electrode interval) between the common electrode and the pixel electrode, the electrode interval is substantially narrower than in the prior art. As a result, the rising of the electric field spreads to the inside of the electrode, and the electric field intensity near the electrode end increases, so that the response speed is improved. When the thickness of the electrode is larger than the thickness of the signal line, the rising of the electric field spreads to the inside of the electrode, and the response speed is improved. And, as in the invention of the present application, if the line width of the electrode is increased and the thickness of the electrode is increased, the above-described effect when the line width of the electrode is increased and the thickness of the electrode are increased. In this case, a synergistic effect can be obtained that is more than simply adding the above effects.

In the present invention, at least one of the common electrode and the pixel electrode may be formed of a transparent conductive layer.

As described above, the distance between the electrodes can be reduced,
If the thickness of the electrode is increased, the electric field distribution spreads over the electrode. Therefore, if a transparent electrode is used instead of the opaque electrode, it is possible to use the portion immediately above the electrode as a display portion, and it is possible to improve the transmittance.

Further, in the present invention, at least one of the common electrode and the pixel electrode is constituted by at least two kinds of conductive layers laminated, and may have a convex sectional shape.

Further, according to the present invention, at least one of the common electrode and the pixel electrode has at least two kinds of different optical characteristics, and each of the common electrode and the pixel electrode is made of a transparent conductor having a different wavelength region from which the best transmittance is obtained. It may have been.

In the present invention, at least one of the common electrode and the pixel electrode may be composed of an insulating layer and a conductive layer formed on the surface thereof.

In the present invention, at least one of the common electrode and the pixel electrode may be composed of a transparent insulating layer and a transparent conductive layer formed on the surface thereof.

In the present invention, the gap between the common electrode and the pixel electrode may be smaller than at least the gap between the array substrate and the counter substrate.

In the present invention, the common electrode and the pixel electrode may be partially or entirely formed of an amorphous transparent conductive film.

[0040]

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[0043]

[0044]

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[0068]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Invention Group] The first invention group of the present invention will be described below with reference to the drawings.

(Embodiment 1-1) An embodiment 1-1 of the present invention will be described with reference to the drawings.

FIG. 1A is a sectional view showing a structure of a liquid crystal display device according to Embodiment 1-1 of the present invention. Fig. 1 (b)
FIG. 1 is a plan view showing a configuration of a liquid crystal display device according to Embodiment 1-1 of the present invention.

The liquid crystal display device employs a lateral electric field application method (IPS
(In-Plane-Swiching) type liquid crystal display device.
This liquid crystal display device has an array substrate-side substrate 1A, a counter substrate 1B, and a liquid crystal 2 sandwiched between the array substrate 1A and the counter substrate 1B.

A red color filter material 8a and a green color filter material 8 are provided on the inner surface of the opposing substrate 1B.
b, blue color filter material 8c, and black matrix 10 are formed in a predetermined pattern. An alignment film 9B is formed on the inner surface of each of the color filter materials 8a, 8b, 8c and the black matrix 10.

On the other hand, on the array substrate side substrate 1A, a plurality of scanning signal lines 6 and video signal lines 5 wired in a matrix, and semiconductor switching devices arranged near intersections of the scanning signal lines 6 and the video signal lines 5 are provided. Thin film transistor (TFT: Thin FiLm Transistor) 7 and substrates 1A and 1
A pair of a common electrode 3 and a pixel electrode 4 for generating an electric field (lateral electric field) parallel to B are formed. The pixel electrode 4 includes an electrode unit 4A to which a video signal from the video signal line 5 is supplied, and a wiring unit 4B. The common electrode 3 includes an electrode unit 3A and a wiring unit 3B. I have. On the inner side surfaces of the common electrode 3 and the pixel electrode 4, an alignment film 9A made of polyimide or the like is formed.

It should be noted that the line widths w1 and w2 of the common electrode 3 and the pixel electrode 4 are determined by the gap l between the common electrode 3 and the pixel electrode 4 (the distance between the electrode section 4A and the electrode section 3A). (W1, w2> l), and the thickness t1 of the common electrode 3 and the pixel electrode 4 is larger than the thickness t2 of the scanning signal line or the video signal line.
With such a configuration, the response speed of the liquid crystal can be increased, and the transmittance can be substantially improved. The reasons for the improvement of the response speed and the transmittance will be described later in detail.

Next, a brief description will be given of a method of manufacturing the liquid crystal display device having the above configuration. First, a scanning signal line 6 patterned with a conductive film made of Al or the like is formed on the array substrate 1A, and an insulating film is formed. Then, a semiconductor switching element 7 made of a-Si or the like, or made of Al or the like is formed. An image signal line 5 patterned with a conductive film is formed.

In this embodiment, a lateral electric field is applied, and the common electrode 3 and the pixel electrode 4 are made of a transparent conductive ITO film,
Alternatively, patterning is performed in a comb shape using a conductive film made of Al or the like.

Further, the array substrate 1A and the counter substrate 1
In B, alignment films 9A and 9B made of polyimide or the like are formed to align the arrangement of the molecules of the liquid crystal 2. The transparent substrate 1B is provided to face the transparent substrate 1A, and includes a red color filter material 8a, a green color filter material 8b, a blue color filter material 8c, and a black matrix 1
0 is formed in a predetermined pattern.

The array substrate 1A and the counter substrate 1B manufactured as described above each have an initial alignment direction in a predetermined direction, and the periphery is adhered with a sealant, and then the liquid crystal 2 is injected and sealed. Thus, a liquid crystal display device is manufactured.

The display operation of the liquid crystal display thus manufactured will be described. Semiconductor switching element 7
Are turned on and off by drive signals input from the video signal line 5 and the scanning signal line 6. The pixel electrode 4 connected to the semiconductor switching element 7 and the common electrode 3
Then, an electric field is generated by the voltage applied between the pixels, and the orientation of the liquid crystal 2 is changed to control the luminance of each pixel, thereby displaying an image.

Next, an electrode structure which is a main feature of the present invention will be described. In FIGS. 1A and 1B, d
Is the cell gap, w1 and w2 are the common electrode 3 and the pixel electrode 4
, L is the distance (gap) between the common electrode 3 and the pixel electrode 4, t
1 is the thickness of the common electrode 3, t2 is the thickness of the pixel electrode 4, t5
Indicates the thickness of the video signal line 5 and the scanning signal line 6.

In the conventional configuration, for example, Japanese Patent Laid-Open No. 7-360
No. 58, the common electrode 3 is formed of a metal such as Cr or Al based on the same process as the scanning signal line 6, and the pixel electrode 4 is formed of Mo or Al based on the same process as the video signal line 5. And the like. Therefore, the film thickness of the common electrode 3 formed by such a process becomes the same as that of the scanning signal line 6, and the film thickness of the pixel electrode 4 becomes the same as that of the video signal line 5.

On the other hand, in the present embodiment, as shown in FIG. 1, the line widths w1 and w2 of the common electrode 3 and the pixel electrode 4 are set to be larger than the gap 1 between the common electrode 3 and the pixel electrode 4. (W
1, w2> l), and the thickness t1 of the common electrode 3 and the thickness t2 of the pixel electrode 4 are larger than the thickness t5 of the scanning signal line or the video signal line (t1, t2> t5). This is a point where the present embodiment is greatly different from the conventional example.
The present invention is not limited to the configuration of w1, w2> l and t1, t2> t5, and may be a configuration of only w1, w2> l or a configuration of only t1, t2> t5.

With such an electrode configuration, high-speed response can be obtained, and if a transparent electrode is used as the electrode, the transmittance can be improved. The reason is shown in Figure 2 below.
This will be described in detail with reference to FIG. In FIG. 2, the curve indicated by reference numeral M1 indicates the electric field distribution of the conventional example, the curve indicated by reference sign M2 indicates the electric field distribution when only the film thickness is large, and the curve indicated by reference sign M3 indicates that only the electrode interval is narrow. The curve indicated by reference numeral M4 indicates the electric field distribution when the film thickness is increased and the distance between the electrodes is reduced.

FIG. 2 (a) shows a conventional example, and FIG. 2 (b) shows an example in which the electrode spacing is the same as the conventional example and only the film thickness is increased.

As the film thickness is increased, FIG.
As shown in (b), a large electric field intensity is generated. As a result, the electric field intensity on the electrode is higher than that of the conventional example shown in FIG. 2A, so that the liquid crystal molecules located immediately above the electrode can be driven. In the conventional example,
The electric field strength was in the state shown in FIG. 2A, and the liquid crystal molecules were driven only between the electrodes, and the liquid crystal molecules just above the electrodes could not be driven. Therefore, in the example shown in FIG. 2B, since the liquid crystal molecules directly above the electrodes can be driven,
If such an electrode is a transparent electrode, the transmittance can be improved. The electric field strength between the electrodes is also higher than in the conventional example. Therefore, also from this viewpoint, a high-speed response and a high transmittance characteristic can be obtained.

Next, FIG. 2C shows an example in which the film thickness is the same as that of the conventional example, and only the electrode interval is reduced. Thus, when the electrode spacing is smaller than in the conventional example, the electric field strength between the electrodes becomes larger than in the conventional example. Furthermore,
Even on the electrodes, the electric field intensity is large enough to drive the liquid crystal molecules. Therefore, as shown in FIG. 2C, when the electrode spacing is reduced, the electric field intensity on the electrodes and between the electrodes can be increased as compared with the conventional example, so that high-speed response can be obtained. Further, by using a transparent electrode as the electrode, the aperture ratio can be improved and the substantial transmission can be improved by driving the liquid crystal molecules on the electrode. Therefore, FIG.
Also in the configuration of (c), high-speed response and high transmittance characteristics can be obtained.

Next, FIG. 2D shows that the film thickness is increased,
In addition, an example in which the electrode interval is reduced is shown. FIG. 2 (d)
The configuration shown in FIG. 2 is obtained by adding the configuration shown in FIG. 2C to the configuration shown in FIG. However, it should be noted that the configuration shown in FIG. 2D is characterized in that a synergistic effect is obtained that is more than the effect obtained by simply adding the effect of reducing only the electrode spacing to the effect obtained only by the film thickness. That is, as shown in FIG. 2D, the electric field strength is equal to or greater than the sum of the electric field strength shown in FIG. 2B and the electric field strength shown in FIG. Have been obtained. The reason is presumed that the effect of the electric field strength due to the change in the film thickness and the effect of the electric field strength due to the change in the electrode interval act synergistically.

The present inventors actually manufactured a liquid crystal display device having the configuration shown in FIGS. 2A to 2D based on the above principle, and performed experiments.

Specifically, three samples were prepared as the samples of the present embodiment. In sample (1), the electrode gap l = 6 μm, the electrode width w = 10 μm, and the cell gap d
= 4 μm, t1 = t2 = 0.4 μm, and sample (2) has an electrode gap l = 6 μm, an electrode width w = 10 μm, a cell gap d = 4 μm, and t1 = t2 = 8000 °.
In sample (4), electrode gap l = 10 μm, electrode width w = 6 μm
m, cell gap d = 4 μm, and t1 = t2 = 0.4 μm.

A sample (3) was prepared as a sample of the conventional example. Sample (3) has an electrode gap l = 10
μm, electrode width w = 6 μm, cell gap d = 4 μm, t
1 = t2 = 2000 °

The conditions were the same except for the electrode configuration, that is, the liquid crystal material was the same, the cell gap d was 4 μm, and the driving voltage was 5
V, the response speed was measured for the samples (1) to (4) under the same environment. FIG. 3 shows the measurement results of the rise time τrise of the samples (1) to (4). The solid line is the conventional sample (3), the dashed line is the sample (1), the dashed line is the sample (2), and the two points are the two. The chain line shows the response characteristics of the sample (4). As is clear from these results, the rise time of the 90% response is
Compared to the conventional sample (3), the sample (1) has about 1
The sample (2) is reduced to about 1/4, which indicates that the present embodiment is effective for high-speed response.

For reference, conventionally, the electrode line widths w1 and w2 are smaller than the electrode interval l (w1, w2 <
l) It was set. This is for the following reason. That is, conventionally, the pixel electrode and the common electrode use opaque electrodes of Al or the like. Therefore, in order to increase the aperture ratio, it is necessary to increase the electrode interval l. However, if the width is too large, the response speed deteriorates, and the electrode line width within one pixel is determined in relation to the wiring, and there is a limit to excessively widening the electrode interval. Therefore, in the related art, it is considered that the design concept is based on the idea that the electrode interval is increased as much as possible while taking into account conditions such as the electrode line width and the response speed. That is, conventionally, there was no idea to narrow the electrode interval. In this regard, the present invention is based on the technical idea of reducing the electrode spacing, and is essentially different from the conventional example.

The present invention is also unconventional in terms of increasing the thickness of the electrode. Conventionally, a pixel electrode and a common electrode have been simultaneously manufactured during the manufacturing process of a scanning line and a video signal line. At this time, it is preferable that the wiring resistance is small for writing a video signal, and that the thickness of the wiring is small for that purpose. Therefore,
At present, the wiring such as the video signal line is formed thin, and accordingly, the thickness of the electrode is also thin. In summary, the thickness of the electrode was the same as the thickness of the wiring such as the video signal line and was thin. Therefore, conventionally, there is no technical idea of making the thickness of the electrode different from the thickness of the wiring, and in this regard, the technical idea is essentially different from that of the present invention in which the thickness of the electrode is changed.

In the above example, the common electrode 3 and the pixel electrode 4
The case where a non-transmissive metal such as Cr or Al is used is described above.
The case where a transparent electrode such as O is used will be described below.

Generally, ITO used for the common electrode 3 and the pixel electrode 4 is formed at a temperature of about 200 ° C., but the crystallization temperature of the ITO is about 100 to 200 ° C. Is a film in which both amorphous and polycrystalline are mixed. If an attempt is made to form a thicker film using such a film in which amorphous and polycrystals are mixed, the surface becomes rough, the light scattering value increases, and the light use efficiency decreases. Therefore, in general, the ITO film is used with a thickness of about 700 °, and Cr used for the video signal line 5 and the scanning signal line 6 is used.
Or, in the case of a non-transmissive metal such as an Al type (film thickness 12
(Approximately 00 to 2000 mm). Therefore, in the conventional ITO film, it is difficult to increase the film thickness in order to improve the transmittance, and as described above, it is difficult to increase the film thickness for high-speed response.

However, if the ITO is amorphous, the surface is smooth, so that even if the film thickness is increased, the light scattering value does not increase and the transmittance does not significantly decrease. In the case of amorphous ITO, in order to provide a transmittance peak at a wavelength of 550 nm, the film thickness needs to be about 1500 °.
Therefore, in order to achieve both an improvement in transmittance and a high speed response, it is desirable that the film thickness is 1500 ° or more.

That is, if amorphous ITO is used, Cr or Al used for the video signal line 5 and the scanning signal line 6 can be used.
Film thickness (1200 mm) similar to non-transmissive metal
Å2000 °) also has the effect of increasing the response speed as compared with the conventional ITO film. Of course, it is thicker than the video signal line 5 and the scanning signal line 6, for example, 2000 mm.
If the film thickness is increased as described above, a higher response speed can be achieved. However, it is necessary to optimize the film thickness in a trade-off relationship with a decrease in optical characteristics such as transmittance and light scattering value due to the increase in film thickness.

To obtain such an amorphous ITO, 10
The film is formed at a low temperature of 0 ° C. or less. Further, if H ₂ O or H ₂ is added to form a film without heating, it is possible to prevent the ITO from being microcrystallized due to a decrease in the residual H ₂ O partial pressure in the chamber, and to provide a stable non-heated film. Crystallinity can be obtained.

Further, ITO is used in a process at 100 ° C. or lower.
Can be formed, so that both or one of the array substrate 1A and the counter substrate 1B can be made of a transparent resin plate such as polycarbonate. Therefore, it is possible to obtain a light-weight liquid crystal display device, and it is possible to reduce breakage and chipping of the substrate generated during handling and transportation during manufacturing. In addition, cracking and chipping of the substrate due to impact due to dropping or falling down during use can be reduced.

FIG. 4 shows an embodiment in which the common electrode 3 and the pixel electrode 4 are formed in a two-stage process so as to have a convex sectional shape.

That is, in the first process, 3 ′ and 4 ′ conductive layers (thickness t1 ′ = t2 ′ = 4000 °, electrode width w1 ′ = w2 ′ = 1)
0 μm) and a 3 ″, 4 ″ conductive layer (thickness t1 ″ = t2 ″ = 4000 °, electrode width w1 ″ = w2 ″ = 6 μm) in the second process.
m), the cross-sectional shapes of the common electrode 3 and the pixel electrode 4 were made convex. Even with such a convex cross-sectional shape, substantially the same effect as that of the sample (2) in FIG. 3 could be obtained.

Therefore, the cross-sectional shape of the common electrode 3 and the pixel electrode 4 does not necessarily have to be a rectangular shape. It may be removed to form an R shape or a tapered cross section.

(Embodiment 1-2) Next, an embodiment 1-2 of the present invention will be described with reference to the drawings.

FIG. 5 is a sectional view showing the structure of the liquid crystal display device according to Embodiment 1-2 of the present invention. In FIG. 5, 3M and 4M are transparent resin layers, and 3N and 4N are transparent conductive layers. That is, the common electrode 3 is formed of the transparent resin layer 3M and the conductive layer 3M.
N, the pixel electrode 4 is composed of a transparent resin layer 4M and a conductive layer 4N.
Consists of Also, d is the cell gap, w1 and w2 are the widths of the common electrode 3 and the pixel electrode 4, and l is the common electrode 3 and the pixel electrode 4.
, T1a is the thickness of the transparent resin layer 3M of the common electrode 3, t2a is the thickness of the transparent resin layer 4M of the pixel electrode, t1b is the thickness of the transparent conductive layer 3N of the common electrode 3, and t2b is the pixel. Electrode 3
Thickness of the transparent conductive layer 4N.

For example, if a photosensitive resin of an acrylic polymer is used for the transparent resin layers 3M and 4M, 1 μm can be easily obtained.
With a film thickness of about m, a desired pattern such as a comb shape can be formed. For the transparent conductive layers 3N and 4N, for example, ITO is used.

In the present embodiment, the cell gap d = 4 μ
m, electrode gap l = 3 μm, electrode width w = 10 μm, t1a =
t2a = 1 μm and t1b = t2b = 2000 °.

In Embodiment 1-2, the electrode gap 1 between the common electrode 3 and the pixel electrode 4 is configured to be smaller than the gap d between the array substrate 1A and the counter substrate 1B. I have. With such a configuration, it is possible to modulate the liquid crystal on each of the electrodes by making use of the fact that the electric field strength around the common electrode 3 and the pixel electrode 4 increases, and the common electrode 3 and the pixel electrode 4 Is composed of a transparent layer, so that light on the electrodes can be transmitted.

A specific description will be given with reference to FIG. FIG.
FIG. 6A is a cross-sectional view of a conventional example (when l> d), and FIG.
FIG. 6B is a diagram schematically illustrating a region where liquid crystal is driven in a conventional example (when l> d), and FIG. 6C is a cross-sectional view of the present invention (when l <d); FIG. 6B is a diagram schematically showing a region where the liquid crystal is driven in the present invention (when l <d). In the conventional example, the liquid crystal molecules on the electrodes are not driven, and only the liquid crystal molecules in the hatched area S1 in FIG. 6A are driven. On the other hand, in the present invention, as shown by the hatched area S2 in FIG. At this time, since the electrode in the present invention uses a transparent electrode, a region on the electrode can be used as a liquid crystal display region. Therefore, the transmittance can be improved. The electric field intensity between the electrodes is larger in the conventional example than in the present invention. However, the area of the liquid crystal driven by the electric field is larger in the present invention than in the conventional example. That is,
As shown in FIGS. 6B and 6D, the region where the liquid crystal is driven has a height H1> H2, but the region S1 <S2.
It is. Therefore, when viewed from the entire liquid crystal panel, the present invention can provide a liquid crystal display device which is brighter and has higher contrast than the conventional example. Moreover, FIG.
As shown in (d), the change in the electric field distribution on the electrode is gradual, so that uniform display without display unevenness is possible.

As described above, according to the present embodiment, it is possible to obtain a liquid crystal panel with high response without lowering the transmittance.

The present embodiment is an embodiment in which it is desired to increase the electrode layer thickness t1 without lowering the transmittance of the electrode portion.
An effect similar to or greater than 1 can be obtained.

(Embodiment 1-3) Next, an embodiment 1-3 of the present invention will be described with reference to the drawings.

FIG. 5 is a sectional view showing the structure of the liquid crystal display device according to the second embodiment of the present invention.

In FIG. 5, 3-I represents the first electrode of the common electrode 3.
Layer, 3-II is the second layer of the common electrode 3, 3-III is the third layer of the common electrode 3, 4-I is the first layer of the pixel electrode 3, 4-I
I is the second layer of the pixel electrode 4, and 3-III is the third layer of the common electrode 3.

In this embodiment, 3-I and 4-I are red (R), that is, a wavelength region around 700 nm, 3-II, 4-I.
-II is green (G), that is, a wavelength region around 546 nm,
3-III and 4-III are formed by adjusting the respective film components and film thicknesses so as to have the spectral characteristics of obtaining the best transmittance in blue (B), that is, the wavelength region around 436 nm. ITO electrode.

With this configuration, it is possible to increase the thicknesses t1 and t2 of the electrode layers without lowering the overall transmittance.

In the above example, the common electrode and the pixel electrode
Although it was composed of three layers having spectral characteristics respectively corresponding to red (R), green (G) and blue (B), the present invention is not limited to this, and red (R), green (G) and a layer having spectral characteristics corresponding to at least one type of blue (B). In addition, the present invention is not limited to red (R), green (G), and blue (B), but also has a layer having spectral characteristics that can obtain the best transmittance in other desired wavelength regions depending on the application to be used. May be configured.

[Second Invention Group] The second invention group relates to a liquid crystal display device in which pixel electrodes and common electrodes are of a stacked type. Hereinafter, a second invention group of the present invention will be described with reference to the drawings.

(Embodiment 2-1) FIG. 8A is a sectional view showing a structure of a liquid crystal display device according to an embodiment 2-1. FIG. 8B is a plan view illustrating a configuration of the liquid crystal display device according to Embodiment 2-1. FIG. 8C shows the second embodiment.
FIG. 9 is a cross-sectional view illustrating a configuration of the liquid crystal display device in FIG. 1, and is a cross-sectional view along AA in FIG.

FIG. 9 is an enlarged cross-sectional view showing a configuration near the semiconductor switching element 7 of the liquid crystal display device according to the embodiment 2-1.

In FIG. 8, 1A is an array substrate, 1B is a counter substrate, 2 is a liquid crystal, 3 is a common electrode, 4 is a pixel electrode,
Is a video signal line connected to the pixel electrode 4 and providing a video signal;
Reference numeral 6 denotes a scanning signal line, 7 denotes a semiconductor switching element, 8 denotes a first insulating layer, 9A denotes an alignment film formed on the inner surface of the array substrate 1A, 9B denotes an alignment film formed on the inner surface of the counter substrate 1B, 10
a is a red color filter material, 10b is a green color filter material, 10c is a blue color filter material, 1
1 is a black matrix (light shielding layer) and 12 is a second insulating layer.

In FIG. 9, 7a is an a-Si layer, 7b is an n + -type a-Si layer, 8a is a contact hole provided in the first insulating layer 8, and 12a is a contact hole provided in the second insulating layer 12. is there.

Hereinafter, a method for manufacturing the liquid crystal display device having the above configuration will be described with reference to FIGS.

First, a non-transmissive conductor made of Al, Ti, or the like is formed on the array substrate 1A, and the wiring portion 3d of the common electrode is formed.
And the scanning signal lines 6 are patterned into a predetermined shape. After forming the first insulating layer 8 on the first electrode group thus formed, a-Si is formed on a predetermined portion of the first insulating layer 8.
The semiconductor switching element 7 including the layer 7a and the n + -type a-Si layer 7b is formed. Further, a non-transmissive conductor made of Al, Ti, or the like is formed on a predetermined portion of the first insulating layer 8 and the semiconductor switching element 7, and a second electrode group including a video signal line and a pixel electrode is formed into a predetermined shape. Form a pattern.

Next, a second insulating layer 12 made of SiNx or the like is formed on the array substrate 1A on which the second electrode group is formed. The second insulating layer 12 also serves as a protective film for protecting the semiconductor switching element 7.

Further, the electrode portions 3a, 3b, 3
c is formed of an ITO film which is a transparent conductor.

Here, in order to obtain electrical continuity between the wiring portion 3d of the common electrode formed of a non-transmissive conductor and the electrode portions 3a, 3b and 3c of the common electrode formed of a transparent conductor, The first insulating layer 8 and the second insulating layer 12 are provided with contact holes 8a and 12a, respectively.

Thereafter, the array substrate 1A and the counter substrate 1
In B, alignment films 9A and 9B made of polyimide or the like are formed to align the arrangement of the molecules of the liquid crystal 2.

The transparent substrate 1B is provided to face the transparent substrate 1A, and includes a red color filter material 10a, a green color filter material 10b, a blue color filter material 10c,
And the black matrix 11 are formed in a predetermined pattern.

The array substrate 1A and the counter substrate 1B thus manufactured each have an initial orientation in a predetermined direction, and the peripheral portion is bonded with a sealant, and then the liquid crystal 2 is injected and sealed.

The semiconductor switching element 7 is connected to the video signal line 5
On / off control is performed by a driving signal input from the scanning signal line 6. Then, an electric field is generated by a voltage applied between the pixel electrode 4 connected to the semiconductor switching element 7 and the common electrode 3, and the orientation of the liquid crystal 2 is changed to control the luminance of each pixel, thereby displaying an image. indicate.

In FIG. 8, d is the cell gap, w1 is the line width of the electrode portion 3b of the common electrode, w2 is the line width of the electrode portion 4a of the pixel electrode, w1 'is the line width of the electrode portion 3a of the common electrode, l
Indicates the distance (gap) between the electrode portion 3b of the common electrode and the electrode portion of the pixel electrode 4a.

In the present embodiment, as shown in FIG. 8, the line width w1 of the electrode portions 3a, 3b, 3c of the common electrode is 5 μm,
The line width w2 of the electrode portions 4a and 4b of the pixel electrode is 4 μm, the cell gap d is 4 μm, and the interval (gap) between the electrodes is l = 10.
μm. That is, the line widths w1 and w2 of the respective electrode portions of the common electrode 3 and the pixel electrode 4 are configured to be substantially the same as the gap d (cell gap) between the array substrate and the counter substrate.

As shown in FIG. 8 (b), for example, as shown in FIG. 8 (b), the electrode portions of the common electrode 3 and the pixel electrode 4 are patterned in a comb shape in which the electrode portions are mutually arranged. A horizontal electric field is formed between the electrode part and the electrode part of the pixel electrode 4. By adopting the above-described electrode configuration, in addition to the lateral electric field, the electric field strength on the electrodes is increased by the peripheral electric field of each electrode, and the liquid crystal is rotated. The upper part also transmits light.

As the liquid crystal material of the liquid crystal layer 2, a cyano-based liquid crystal material containing about 10% to 20% of a cyano-based compound is used, and the retardation Δn · d (the product of the cell gap d and the refractive index difference Δn) is used. ) Was about 350 nm. Further, the splay elastic constant K11 of the liquid crystal material of the liquid crystal layer 2 is K11 = 12.
(PN), twist elastic constant K22 = 7 (pN), bend elastic constant K33 = 18 (pN), dielectric anisotropy Δε = +
8. Here, the dielectric anisotropy Δε and the elastic constant K 33 of the bend are important in determining the driving voltage of the liquid crystal.
In particular, the dielectric anisotropy Δε is +8 or more, and the bend elastic modulus K
33 is desirably 18 (pN) or less.

By combining the above-described electrode configuration with the liquid crystal layer 2 having such a configuration, it is possible to sufficiently increase the electric field strength on the electrodes with the drive voltage (about 5 V) conventionally applied to drive the liquid crystal. Can be.

Further, since the direction of rotation of the liquid crystal molecules is divided into two directions by bending the comb-shaped electrode portion, the coloring in the viewing angle direction is canceled each other, and the panel configuration in which the color change in the viewing angle direction is small. It can be. Although not shown here, if the video signal lines 5 and the black matrix 11 are also formed into a bent shape having the same bending angle as the electrode portions of the common electrode 3 and the pixel electrode 4, the electrode portions are bent. Thus, the increase in the light shielding area can be eliminated, and a liquid crystal panel having a higher aperture ratio can be obtained.

Next, the operation and effect of the panel configuration according to the present embodiment will be described.

FIG. 10 shows the light transmittance characteristics (calculated from the electric field distribution and the liquid crystal director of the panel) of the liquid crystal panel when the above-described cyano-based liquid crystal material is used in the panel configuration according to the present embodiment. The drive voltage is 5V. The electrode configuration is such that the line (a) in FIG.
a, 3b, 3c, line width w1 = 5 μm, pixel electrodes 4a, 4
1 has a line width w2 = 4 μm, a cell gap d = 4 μm, and an interval (gap) 1 = 10 μm between the electrodes.
The line (b) of 0 is the line width w of the common electrodes 3a, 3b, 3c.
1 = 6 μm, line width w2 of pixel electrodes 4a and 4b = 6 μm, cell gap d = 4 μm, interval (gap) between electrodes l = 11
μm.

[0139] In general, ITO is slightly more difficult to form a finer patterning than Al, Ti, etc., so the line width is set slightly larger than that of Al, Ti, etc. Since Al and Ti are non-transmissive conductors that do not transmit light, it is desirable to make them as fine as possible. However, since ITO transmits light, it is not possible to greatly reduce the aperture ratio even if the line width is slightly increased. Absent.

That is, the line (a) and the line (b) in FIG. 10 are comparisons of light transmittance characteristics in a liquid crystal panel configuration in which only the electrode line width and the electrode interval are different.

Further, with the same electrode and panel configuration as in FIG.
Liquid crystal material only fluorinated liquid crystal material (spray elastic constant K11
= 9 (pN), twist elastic constant K22 = 9 (pN), bend elastic constant K33 = 22 (pN), dielectric anisotropy Δε = + 4.
FIG. 11 shows the light transmittance characteristics of the liquid crystal panel when (4) is used (the light transmittance of the panel is calculated from the electric field distribution and the liquid crystal director). The drive voltage is 5 V as in FIG.

As is clear from the results, the structure shown in FIG. 10 using the cyano-based liquid crystal material can obtain higher transmittance than the structure shown in FIG. 11 using the fluorine-based liquid crystal material. You can see that.

In particular, FIG. 11 using a fluorine-based liquid crystal material is used.
In the configuration shown in FIG. 10, almost no light is transmitted through the portion on the electrode, but the configuration shown in FIG. 10 using a cyano-based liquid crystal material can transmit at least about 10% to 20% of the light. When a transparent conductive layer such as that described above is used, the substantial aperture ratio is greatly improved. Further, as the electrode line width becomes smaller, the electric field intensity becomes stronger and the transmittance on the electrode is improved. However, if the influence of the vertical electric field is too strong, the change in color due to the viewing angle becomes too large. Therefore, it is desirable that the electrode line width be at most about 4 μm.

Further, when the scanning signal line 6 and the common electrode 3 are formed in the same layer, the comb portions 3a, 3b, 3c
And the scanning signal line 6 are arranged very close to each other, so that the probability of occurrence of a defect due to short-circuit is high. However, in the configuration according to the present embodiment, the comb portions 3a, 3b, 3c of the common electrode 3 are connected to the scanning signal line 6. Since they are formed in different layers, defects due to short circuits can be eliminated.

In the present embodiment, an example in which a-Si (amorphous silicon) is used for the semiconductor switching element 7 has been described, but p-Si (polysilicon) is used.
The same effect can be obtained by using another semiconductor layer.

In this embodiment, an example of a bent electrode has been described. However, an effect of substantially improving the aperture ratio can be obtained regardless of the shape of the electrode, such as a linear electrode or an enclosed electrode. be able to.

(Embodiment 2-2) FIG. 12A is a sectional view showing the structure of a liquid crystal display device according to Embodiment 2-2. FIG. 12B is a plan view illustrating a configuration of a liquid crystal display device according to Embodiment 2-2. FIG. 12C is a cross-sectional view illustrating a configuration of the liquid crystal display device according to Embodiment 2-2, and is a cross-sectional view taken along line AA of FIG.

FIG. 13 is an enlarged cross-sectional view showing the structure near the semiconductor switching element of the liquid crystal display device according to the embodiment 2-2.

In the present embodiment, the electrode portion 4a of the pixel electrode,
4b is an embodiment when a transparent conductor is used for 4b,
This is different from the embodiment 2-1.

Hereinafter, the operation will be described with reference to FIGS.

First, a non-transmissive conductor made of Al, Ti or the like is formed on the array substrate 1A, and the common electrode 3 and the scanning signal line 6 are patterned into a predetermined shape. After the first insulating layer 8 is formed on the first electrode group thus formed, the a-Si layer 7a and n + are formed on predetermined portions of the first insulating layer 8.
Semiconductor switching element 7 comprising a-Si layer 7b
To form Further, a non-transmissive conductor made of Al, Ti, or the like is formed on predetermined portions of the first insulating layer 8 and the semiconductor switching element 7, and a second electrode group including the video signal line 5 and the pixel electrode wiring portion 4c is formed. Is formed into a predetermined pattern.

Next, a second insulating layer 12 made of SiNx or the like is formed on the array substrate 1A on which the second electrode group is formed. The second insulating layer 12 also serves as a protective film for protecting the semiconductor switching element 7.

Further, the comb portions 4a and 4b of the pixel electrode are formed of an ITO film which is a transparent conductor.

Here, in order to obtain conduction between the wiring portion 4c of the pixel electrode formed of the non-transmissive conductor and the electrode portions 4a and 4b of the pixel electrode formed of the transparent conductor, the second insulating layer 12 is provided with a contact hole 12a.

The other parts such as the electrode shape and the liquid crystal material may be the same as those in Embodiment 2-1.

With such a configuration, it is possible to obtain a liquid crystal panel having a substantially high aperture ratio, as in the embodiment 2-1.

(Embodiment 2-3) FIG. 14A is a sectional view showing a structure of a liquid crystal display device according to Embodiment 2-3. FIG. 14B is a plan view showing a configuration of the liquid crystal display device according to Embodiment 2-3. FIG. 14C is a cross-sectional view illustrating a configuration of the liquid crystal display device according to Embodiment 2-3, and is a cross-sectional view taken along line AA of FIG. 14B.

FIG. 15 is an enlarged cross-sectional view showing the configuration near the semiconductor switching element of the liquid crystal display device according to the embodiment 2-3.

In the present embodiment, the electrode portions 3a of the common electrode
This is an embodiment in which a transparent conductor is used for both the electrodes 3b and 3c and the electrode portions 4a and 4b of the pixel electrodes, and is different from the embodiments 2-1 and 2-2 in this point. .

Hereinafter, the operation will be described with reference to FIGS. 14 and 15.

First, a non-transmissive conductor made of Al, Ti or the like is formed on the array substrate 1A, and the wiring portion 3d of the common electrode is formed.
And the scanning signal lines 6 are patterned into a predetermined shape. After the first insulating layer 8 is formed on the first electrode group formed in this way, the a-Si layer 7a and the n + -type a-Si layer 7b are formed on predetermined portions of the first insulating layer 8. Is formed. Further, a non-transmissive conductor made of Al, Ti, or the like is formed on predetermined portions of the first insulating layer 8 and the semiconductor switching element 7, and a second electrode group including the video signal line 5 and the pixel electrode wiring portion 4c is formed. Is formed into a predetermined pattern.

Next, the second insulating layer 12 made of SiNx or the like is formed on the array substrate 1A on which the second electrode group is formed. The second insulating layer 12 also serves as a protective film for protecting the semiconductor switching element 7.

Further, the electrode portions 3a, 3b, 3
c is formed of an ITO film which is a transparent conductor, and after the third insulating layer 13 made of SiNx or the like is formed, the electrode portions 4a and 4b of the pixel electrodes are formed of an ITO film which is a transparent conductor.

Here, in order to obtain electrical continuity between the wiring portion 3d of the common electrode formed of the non-transmissive conductor and the comb portions 3a, 3b, 3c of the common electrode formed of the transparent conductor,
Contact holes 8 are formed in first insulating layer 8 and second insulating layer 12.
a, 12b, and in order to obtain electrical continuity between the wiring portion 4c of the pixel electrode formed of a non-transmissive conductor and the electrode portions 4a and 4b of the common electrode formed of a transparent conductor,
The contact holes 12a and 13a are provided in the second insulating film 12 and the third insulating layer 13.

The electrode shape, the liquid crystal material and the like of the other parts are the same as those in the first embodiment or the second embodiment.
Same as -2.

With such a configuration, the embodiment 2-1
Alternatively, it is possible to obtain a liquid crystal panel having a substantially higher aperture ratio than Embodiment 2-2 or higher.

(Embodiment 2-4) FIG. 16 is an enlarged cross-sectional view showing a configuration near a semiconductor switching element of a liquid crystal display device according to an embodiment 2-4.

This embodiment is different from the above-described embodiment 2-3.
Similarly to the above, this embodiment is an embodiment in which a transparent conductor is used for both the electrode portions 3a, 3b, 3c of the common electrode and the electrode portions 4a, 4b of the pixel electrode. This is an embodiment, and in this regard, the above-described Embodiment 2
Different from 3.

Therefore, when manufacturing the liquid crystal display device according to Embodiment 2-4, the steps up to the step of forming the second electrode group and forming the second insulating layer may be the same as those of Embodiment 2-3. The electrode portions 3a and 3 of the common electrode are formed on the second insulating layer.
Both b and 3c and the electrode portions 4a and 4b of the pixel electrode are formed of a transparent conductor.

With such a configuration, a liquid crystal having a smaller number of processes than that of the above-described embodiment 2-3 and having a substantially higher aperture ratio than the above-mentioned embodiment 2-1 or the above-mentioned embodiment 2-2. It is possible to get a panel.

(Embodiment 2-5) FIG. 17A is a sectional view showing a structure of a liquid crystal display device according to an embodiment 2-5. FIG. 17B is a plan view illustrating a configuration of a liquid crystal display device according to Embodiment 2-5.

In FIG. 17, 1A is an array substrate, 1B
Is a counter substrate, 2 is a liquid crystal, 3 is a common electrode, 4 is a pixel electrode,
Reference numeral 5 denotes a video signal line connected to the pixel electrode 4 to supply a video signal, 6 denotes a scanning signal line, 7 denotes a semiconductor switching element, 8
Is a transparent insulating layer, 9A is an alignment film formed on the inner surface of the array substrate 1A, 9B is an alignment film formed on the inner surface of the counter substrate 1B,
10a is a red color filter material, 10b is a green color filter material, 10c is a blue color filter material, and 11 is a black matrix (light shielding layer).

Hereinafter, the manufacture of the liquid crystal display device having the above configuration will be described with reference to FIG.

First, a scanning signal line 6 patterned with a conductive film made of Al or the like is formed on the array substrate 1A, and an insulating film is formed. Then, a semiconductor switching element 7 made of a-Si or the like, A video signal line 5 patterned with a conductive film made of is formed.

In the present embodiment, a lateral electric field is applied, and the common electrode 3 and the pixel electrode 4 are formed by using an ITO film as a transparent conductor,
Alternatively, a conductive film made of Al or the like is patterned into a comb shape as shown in FIG.

The pixel electrode 4 is formed of the same layer as that on which the video signal line 5, the scanning signal line 6, or the semiconductor switching element 7 is formed, and is formed of a transparent conductor such as an ITO film.

Further, after forming a transparent insulating layer 8 having a thickness sufficient to flatten these wirings, a common electrode 3 made of an ITO film as a transparent conductor is formed.

The line width w1 'of the common electrode portions 3a and 3d immediately above the video signal line 5 is different from the other common electrode electrode portions 3a and 3d.
The line widths b and 3c are set to be larger than w1.

Thereafter, the array substrate 1A and the counter substrate 1
In B, alignment films 9A and 9B made of polyimide or the like are formed to align the arrangement of the molecules of the liquid crystal 2.

The counter substrate 1B is provided so as to face the array substrate 1A, and includes a red color filter material 10a, a green color filter material 10b, and a blue color filter material 10b.
c and the black matrix 11 are formed in a predetermined pattern.

The array substrate 1A and the counter substrate 1B manufactured as described above each have an initial alignment direction in a predetermined direction, and the peripheral portion is adhered with a sealant, and then the liquid crystal 2 is injected and sealed.

The semiconductor switching element 7 is connected to the video signal line 5
On / off control is performed by a driving signal input from the scanning signal line 6. Then, an electric field is generated by a voltage applied between the pixel electrode 4 connected to the semiconductor switching element 7 and the common electrode 3, and the orientation of the liquid crystal 2 is changed to control the luminance of each pixel, thereby displaying an image. indicate.

In FIG. 17, d is the cell gap, w1
Is the line width of the electrode portion 3b of the common electrode, w2 is the line width of the electrode portion 4a of the pixel electrode, w1 'is the line width of the electrode portion 3a of the common electrode,
1 indicates a distance (gap) between the electrode portion 3b of the common electrode and the electrode portion 4a of the pixel electrode.

In the present embodiment, as shown in FIG.
The line widths w1 and w2 of the electrode portion 3b of the common electrode and the electrode portion 4a of the pixel electrode are smaller than the cell gap d (w1, w2).
<D), the interval (gap) l is also smaller than the cell gap (l
<D). Further, the pixel electrode 4 is formed in a process before the transparent insulating layer 8 is formed, that is, the pixel electrode 4 is provided on the array substrate 1A side which is a lower layer of the transparent resin layer 8.

Further, the common electrode 3 immediately above the video signal line 5
The line widths w1 'of a and 3d are larger than the line widths w1 of the other common electrodes 3b and 3d (w1'> w1). These points are the points that the present embodiment is greatly different from the conventional example.

In such a configuration, in addition to the lateral electric field, the electric field intensity on each electrode is increased by the peripheral electric field around each electrode, and the liquid crystal is rotated. Therefore, by using a transparent conductive material for the electrode, Will also transmit light.

Further, the common electrode 3 is also provided on the video signal line 5.
Since a is provided, an electric field can be generated between the pixel electrode 4a and the pixel electrode 4a. Therefore, the portion covered with the black matrix 11 can transmit light, and the aperture ratio is substantially improved, so that a high-luminance panel can be obtained.

However, in such a configuration, the electric field distribution differs depending on which layer the common electrode 3 and the pixel electrode 4 are formed.

First, the pixel electrode 4 was formed by a process before the formation of the transparent insulating layer 8, that is, the transparent resin layer 8 was formed.
The function and effect of the structure provided on the array substrate 1A side, which is the lower layer, will be described.

FIG. 18 shows the light transmittance characteristics of the liquid crystal panel having the electrode configuration according to the present embodiment (the light transmittance of the panel is calculated from the electric field distribution and the liquid crystal director).

Specifically, the electrode gap l = 2 μm, the electrode width w1 = w2 = 2 μm, and the cell gap d = 4 μm (that is, w1, w2 <d and l <d are satisfied). The conditions were the same except for the electrode configuration, that is, the conditions were the same for the liquid crystal material, the driving voltage was 5 V, and the same environment.

18 (a) and FIG. 18 (b) is that FIG. 18 (a) shows that both the common electrode 3 and the pixel electrode 4 are formed on the upper layer of the transparent insulating layer 8, that is, the counter substrate 1B. FIG. 18B shows a configuration in which the pixel electrode 4 is formed in a process before the formation of the transparent insulating layer 8, that is, the pixel electrode 4 is provided on the side of the array substrate 1 </ b> A below the transparent resin layer 8. Configuration.

As apparent from the result, FIG.
It can be seen that the configuration of (b) has a higher transmittance. The transmittance was measured on an ultra-high-definition panel having a dot size of 43 μm × 129 μm. As a result, the transmittance without the laminated common electrode was 37%, and the transmittance in the configuration of FIG. 18A was 44%. On the other hand, it was found that the transmittance of the configuration shown in FIG.

Next, the common electrode 3a immediately above the video signal line 5
The function and effect of making the line width w1 ′ of (1) larger than the line width w1 of the other common electrode 3b (w1 ′> w1) will be described.

FIG. 19 shows the results of an electro-optic simulation (calculating the panel transmittance from the electric field distribution and the liquid crystal director) in the case of an electrode configuration having different electrode line widths and electrode spacings from FIG. 18B.

Specifically, the electrode gap l = 10 μm, the electrode width w1 = w2 = 6 μm, and the cell gap d = 4 μm. The conditions were the same except for the electrode configuration, that is, the conditions were the same for the liquid crystal material, the driving voltage was 5 V, and the same environment.

As shown in FIG. 19A, w1 '= w1
= 6 μm, the electric field distribution generated between the common electrode 4a and the pixel electrode 3a immediately above the video signal line 5 is different from the electric field distribution generated between the pixel electrode 3a and the common electrode 4b and is close to the video signal line 5. Since the gradient distribution is such that a stronger electric field is generated, the transmittance distribution is also reduced to the video signal line 5.
, The higher the transmittance becomes. Therefore,
This may cause uneven brightness or coloring.

On the other hand, as shown in FIG.
If the line width of the common electrode 4a immediately above the video signal line 5 is made larger than the line width of the other common electrodes (when w1 ′ = 10 μm> w1), the common electrode 4a and the pixel electrode 3a immediately above the video signal line 5 are obtained.
And the inclination of the electric field distribution generated between the
Coloring can be prevented.

In this embodiment, w1, w
Although an example of a configuration that does not satisfy 2 <d and l <d has been described, it is needless to say that a configuration that satisfies w1, w2 <d and l <d can also obtain the same effect.

(Embodiment 2-6) FIG. 20A is a sectional view showing a structure of a liquid crystal display device according to Embodiment 2-6. FIG. 20B is a plan view showing the configuration of the liquid crystal display device according to Embodiment 2-6. FIG. 20 (c) is FIG. 20 (b)
FIG. 3 is a sectional view taken along line AA shown in FIG.

In FIG. 20, 1A is an array substrate, 1B
Is a counter substrate, 2 is a liquid crystal, 3 is a common electrode, 4 is a pixel electrode,
Reference numeral 5 denotes a video signal line connected to the pixel electrode 4 to supply a video signal, 6 denotes a scanning signal line, 7 denotes a semiconductor switching element, 8
Is a transparent insulating layer, 9A is an alignment film formed on the inner surface of the array substrate 1A, 9B is an alignment film formed on the inner surface of the counter substrate 1B,
10a is a red color filter material, 10b is a green color filter material, 10c is a blue color filter material, 11 is a black matrix (light-shielding layer), and 12 is an insulating layer formed in a process of manufacturing the semiconductor switching element 7.

This embodiment is an embodiment in which the common electrodes 3a and 3d immediately above the video signal line 5 and the other common electrodes 3b and 3c are formed in different layers. This is an embodiment in the case where a high-resistance conductor such as ITO cannot be formed.

Since the manufacturing method of the present embodiment 2-6 is almost the same as that of the above-described embodiment 2-5, only different processes will be described. That is, only the process of forming the common electrode 4 will be described.

As in the embodiment 2-5, the common electrode 3 and the pixel electrode 4 are made of an ITO film which is a transparent conductor or an A film.
A comb-shaped pattern as shown in FIG. 20B is formed by a conductive film made of l, Ti or the like.

The pixel electrode 4 is formed of the same layer as that on which the video signal line 5, the scanning signal line 6, or the semiconductor switching element 7 is formed, and is formed of an ITO film which is a transparent conductor.

Next, after the insulating layer 12 is formed in the step of manufacturing the semiconductor switching element 7, the transparent conductor I
The common electrodes 3b and 3c are formed of a TO film.

Further, after forming a transparent insulating layer 8 having a thickness sufficient to flatten these wirings, Al, Cr
The common electrodes 3a and 3d are formed of a non-transmissive conductive material such as. The common electrodes 3 a, 3 d immediately above the video signal line 5 and the other common electrodes 3 b, 3 c are configured so that electrical continuity can be obtained via contact holes 8 a provided in the transparent insulating layer 8.

Even in such a configuration, since the video signal line 5 is originally formed of a non-transmissive conductive material such as Al, the transmittance is not reduced, and the common electrode immediately above the video signal line 5 is not reduced. 4a and 4d can be formed of a non-transmissive low-resistance conductive material such as Al or Cr.

(Embodiment 2-7) Embodiment 2-7
Will be described with reference to the drawings.

FIG. 21A is a cross-sectional view showing the structure of the liquid crystal display according to Embodiment 2-7. FIG.
(B) is a plan view showing the configuration of the liquid crystal display device in Embodiment 2-7. FIG. 21C shows the second embodiment.
FIG. 7 is a cross-sectional view illustrating the configuration of the liquid crystal display device at −7
FIG. 22 is a cross-sectional view taken along the line AA of FIG.

FIG. 22 is an enlarged sectional view showing a structure near a semiconductor switching element of a liquid crystal display according to Embodiment 2-7 of the present invention.

This embodiment is an embodiment in the case where there is a large amount of impurity ions in the liquid crystal material and the afterimage caused by accumulation of the charge on the electrode, that is, so-called burn-in is remarkable. Embodiment 2-1 to Embodiment 2
-4 different from the configuration described before.

Since the manufacturing method of the present embodiment 2-7 is almost the same as that of the above-described embodiment 2-3, only different processes will be described. That is, only the process of adding the fourth insulating layer 14 and its effect will be described.

The process from the formation of the third insulating layer 13 made of SiNx or the like to the formation of the electrode portions 4a and 4b of the pixel electrodes with the ITO film, which is a transparent conductor, is described in the second embodiment.
Same as -3. In the present embodiment, a fourth insulating layer 14 is further formed.

In the configurations described in the embodiments 2-1 to 2-4, the electrode portions 3a and 3b of the common electrode or the electrode portions 4a and 4b of the pixel electrode are exposed to the uppermost layer. That is, since the alignment film 9A is a very thin film, the liquid crystal 2 almost directly comes into contact with the exposed portion of the electrode, and impurity ions in the liquid crystal 2 accumulate and cause factors such as flicker, afterimage, and image sticking. Become. Therefore, especially when the liquid crystal 2 contains a large amount of impurity ions, flicker, afterimages and image sticking become remarkable, not only deteriorating the image quality but also causing a chemical reaction in a high-temperature and high-humidity environment, which may cause further image defects. There is.

Therefore, the liquid crystal 2 is connected to the electrode portions 3a of the common electrode,
The third insulating layer 14 is provided to prevent direct contact with the electrode portions 3b or the electrode portions 4a and 4b of the pixel electrode.

Here, the fourth insulating layer may be any of the insulating films described in Embodiments 2-1 to 2-6. That is, S used in another process
If an insulating film such as iNx or an acrylic photosensitive resin used for an interlayer insulating film or the like is used, a liquid crystal display device with high image quality and high reliability can be obtained at low cost without adding a manufacturing device.

However, it is desirable that the surface resistance is about 1010 Ω / □ and the film thickness is 50 nm or more in order to surely obtain insulation.

If the fourth insulating layer is made of an SiO ₂ material to which Sb ₂ O _S based fine particles are added, Na +, K +, NH ₄
It is more effective because it has a function of absorbing impurity ions such as +.

[0220]

According to the configuration of the first invention group as described above, the following effects can be obtained.

(1) Since it is not necessary to reduce the cell gap, it is possible to increase the speed without increasing the time required for injecting liquid crystal and without causing unevenness due to variations in gap accuracy. .

(2) Since it is not necessary to change the liquid crystal material or the addition ratio thereof, it is possible to increase the speed without causing a partial abnormality in contrast due to a decrease in heat resistance and light resistance and a display defect such as flicker. It is.

(3) Since it is not necessary to increase the driving voltage, it is possible to increase the speed without increasing the power consumption and using a conventional driving IC.

(4) It is possible to increase the speed without lowering the transmittance.

(5) By the above operation, a liquid crystal display device capable of obtaining a high-speed response and high image quality such as high brightness with a wide viewing angle without changing the liquid crystal material, narrowing the cell gap, or increasing the driving voltage. Therefore, the industrial value is extremely large.

According to the structure of the second invention group, the following effects can be obtained.

(6) The electrode portions of the pixel electrode and the counter electrode are formed of a transparent conductive layer, and an electrode configuration for increasing the electric field strength on the electrodes and a combination of liquid crystal materials are used. Can be modulated to transmit light,
A liquid crystal panel having a substantially high aperture ratio can be obtained.

(7) Since the gate electrode (scanning signal line) and the counter electrode are formed in different layers, an electrical short circuit between the gate electrode and the counter electrode can be significantly reduced.

(8) Since the stacked common electrodes immediately above the video signal lines are arranged in consideration of the influence on the electric field distribution,
High transmittance can be obtained as a whole.

(9) By making the line width of the common electrode immediately above the video signal line larger than the line width of the other common electrodes, a smooth transmittance distribution can be obtained between the common electrode and the pixel electrode immediately above the video signal line. Because of the obtained configuration, a uniform image without luminance unevenness or coloring can be obtained.

(10) From the above, it is possible to provide a liquid crystal display device having a wide viewing angle, high luminance, and high image quality without luminance unevenness, coloring, and the like, so that the industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a liquid crystal display device in Embodiment 1-1.

FIG. 2 is a diagram for describing the principle of an electrode structure in Embodiment 1-1.

FIG. 3 is a diagram illustrating response characteristics of the liquid crystal display device in Embodiment 1-1.

FIG. 4 illustrates a structure of a liquid crystal display device in Embodiment 1-2.

FIG. 5 is a diagram illustrating a configuration of a liquid crystal display device in Embodiment 1-3.

FIG. 6 is a diagram for describing a principle of an electrode structure in the embodiment 1-3.

FIG. 7 is a diagram illustrating a configuration of a liquid crystal display device in Embodiment 1-4.

8A and 8B illustrate a structure of a liquid crystal display device in Embodiment 2-1. FIG. 8A illustrates Embodiment 2;
1 is a cross-sectional view showing the configuration of the liquid crystal display device in FIG.
8B is a plan view illustrating a configuration of the liquid crystal display device according to Embodiment 2-1. FIG. 8C is a cross-sectional view taken along line AA of the configuration of the liquid crystal display device according to Embodiment 2-1. .

FIG. 9 is an enlarged cross-sectional view showing a configuration near a semiconductor switching element of the liquid crystal display device in Embodiment 2-1.

FIG. 10 is a diagram showing light transmittance characteristics of a liquid crystal display device in Embodiment 2-1.

FIG. 11 is a diagram showing light transmittance characteristics of a conventional liquid crystal display device.

12A and 12B illustrate a structure of a liquid crystal display device in Embodiment 2-2. FIG. 12A is a cross-sectional view illustrating a structure of the liquid crystal display device in Embodiment 2-2. FIG. 12B is a plan view illustrating a configuration of the liquid crystal display device according to Embodiment 2-2, and FIG. 12C is a cross-sectional view taken along line AA of the liquid crystal display device according to Embodiment 2-2. It is.

FIG. 13 is an enlarged cross-sectional view showing a configuration near a semiconductor switching element of a liquid crystal display device according to Embodiment 2-2.

14A and 14B are diagrams illustrating a configuration of a liquid crystal display device in Embodiment 2-3. FIG. 14A is a cross-sectional view illustrating a configuration of a liquid crystal display device in Embodiment 2-3.
4 (b) is a plan view illustrating the configuration of the liquid crystal display device according to Embodiment 2-3, FIG. 14 (c) is a cross-sectional view taken along line AA illustrating the configuration of the liquid crystal display device according to Embodiment 2-3, It is.

FIG. 15 is an enlarged cross-sectional view showing a configuration near a semiconductor switching element of the liquid crystal display device according to Embodiment 2-3.

FIG. 16 is an enlarged cross-sectional view showing a configuration near a semiconductor switching element of a liquid crystal display device according to Embodiment 2-4.

17A and 17B are diagrams illustrating a configuration of a liquid crystal display device in Embodiment 2-5. FIG. 17A is a cross-sectional view illustrating a configuration of the liquid crystal display device in Embodiment 2-5.
FIG. 7B is a plan view showing a configuration of the liquid crystal display device according to Embodiment 2-3.

FIG. 18 is a diagram showing light transmittance characteristics of a liquid crystal display device in Embodiment 2-5.

FIG. 19 is a diagram illustrating light transmittance characteristics of a liquid crystal display device in Embodiment 2-5.

20A and 20B illustrate a structure of a liquid crystal display device in Embodiment 2-6. FIG. 20A is a cross-sectional view illustrating a structure of the liquid crystal display device in Embodiment 2-6.
0 (b) is a plan view illustrating the configuration of the liquid crystal display device according to Embodiment 2-6, FIG. 20 (c) is a cross-sectional view taken along line AA illustrating the configuration of the liquid crystal display device according to Embodiment 2-6, It is.

21A and 21B illustrate a structure of a liquid crystal display device in Embodiment 2-7. FIG. 21A is a cross-sectional view illustrating a structure of the liquid crystal display device in Embodiment 2-7.
1B is a plan view illustrating the configuration of the liquid crystal display device according to Embodiment 2-7, FIG. 21C is a cross-sectional view taken along line AA illustrating the configuration of the liquid crystal display device according to Embodiment 2-7, It is.

FIG. 22 is an enlarged cross-sectional view showing a configuration near a semiconductor switching element of a liquid crystal display device in Embodiment 2-7.

FIG. 23 is a diagram showing a configuration of a first conventional liquid crystal display device.

FIG. 24 is a diagram showing a configuration of a second conventional liquid crystal display device.

[Explanation of symbols]

 1A: Array substrate 1B: Counter substrate 2: Liquid crystal 3: Common electrode 4: Pixel electrode 5: Video signal line 6: Scanning signal line 7: Semiconductor switch device 8: Transparent insulating layer 9A: Alignment film 9B: Alignment film 10a: Red Color filter material 10b: Green color filter material 10c: Blue color filter material 11: Black matrix 12: Insulating layer w1: Line width of common electrode w2: Line width of pixel electrode l: Gap between common electrode and pixel electrode t1: Common Electrode thickness t2: Pixel electrode thickness t6: Video signal line or scanning signal line thickness d: Cell gap w1 ': Line width of common electrode located immediately above video signal line

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 2000-23687 (P2000-23687) (32) Priority date February 1, 2000 (2000.2.1) (33) Priority claim country Japan (JP) Application for accelerated examination (72) Inventor Akinori Shioda 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Ichiro Sato 1006 Odakadoma Kadoma, Osaka Prefecture Incorporated (72) Inventor Yuji Saya 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Masanori Kimura 1006 Odaka, Kazuma, Kadoma, Osaka Pref. Inventor Satoshi Asada 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-9-258265 (JP, A) JP-A-9-146125 (JP, A) JP-A-11 −648 92 (JP, A) JP-A-10-10556 (JP, A) JP-A-9-61836 (JP, A) JP-A 8-190104 (JP, A) JP-A-7-128683 (JP, A) JP-A-10-301141 (JP, A) JP-A-11-119237 (JP, A) JP-A-6-214244 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1343 G02F 1/1368

Claims (8)

(57) [Claims] An array substrate on which common electrodes, pixel electrodes, scanning signal lines, video signal lines, and semiconductor switching elements are formed; a counter substrate; and a liquid crystal layer sandwiched between the array substrate and the counter substrate. A liquid crystal display device that applies a voltage between the pixel electrode and a common electrode, generates a substantially parallel electric field on the substrate, and performs dimming driving of the liquid crystal, wherein at least the common electrode and the pixel electrode One of the line widths is larger than a gap between the common electrode and the pixel electrode, and the film thickness of at least one of the common electrode and the pixel electrode is the scanning signal line and the video signal. A liquid crystal display device having a thickness greater than at least one of the thicknesses of the lines. 2. The liquid crystal display device according to claim 1, wherein at least one of said common electrode and said pixel electrode is formed of a transparent conductive layer. 3. The device according to claim 1, wherein at least one of said common electrode and said pixel electrode is composed of at least two kinds of conductive layers laminated, and has a convex cross-sectional shape. Liquid crystal display. 4. At least one of the common electrode and the pixel electrode has at least two kinds of different optical characteristics, and each is made of a transparent conductor having a different wavelength region from which the best transmittance can be obtained. The liquid crystal display device according to claim 3, wherein: 5. The liquid crystal display device according to claim 1, wherein at least one of said common electrode and said pixel electrode comprises an insulating layer and a conductive layer formed on a surface thereof. 6. The liquid crystal display device according to claim 4, wherein at least one of said common electrode and said pixel electrode comprises a transparent insulating layer and a transparent conductive layer formed on the surface thereof. . 7. The liquid crystal display device according to claim 2, wherein an electrode gap between said common electrode and said pixel electrode is smaller than at least a gap between said array substrate and said counter substrate. . 8. The liquid crystal display device according to claim 1, wherein a part or all of said common electrode and said pixel electrode are made of an amorphous transparent conductive film.