JP2001235761A - Electro-optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-optical device permitting easy gradation control and high-definition display. SOLUTION: When an electric field is applied across a 1st pixel electrode 9A and a 2nd pixel electrode 9B on a TFT array substrate 10 in a liquid crystal display, an alignment state of a liquid crystal 5 is changed according to a lateral electric field (an electric field horizontal to the substrate) or an oblique electric field similarly IPS mode. However, since a counter electrodes 21 is formed on a counter substrate 20, the liquid crystal 5 is also influenced by an electric field (an electric field vertical to the substrate) generated across the pixel electrodes 9A, 9B and the counter electrode 21, in addition to the influence by the electric field generated across the pixel electrodes 9A, 9B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical device for controlling a polarization state of light passing through an electro-optical material by an electric field. More specifically, the present invention relates to the structure of an electro-optical device.

[0002]

2. Description of the Related Art Among various electro-optical devices, there is a liquid crystal device as the most typical electro-optical device. In this liquid crystal device, a liquid crystal as an electro-optical material is held between a pair of substrates, and by applying an electric field to the liquid crystal for each pixel, the alignment state of the liquid crystal is controlled for each pixel to perform various displays.

[0003] Among such liquid crystal devices, in a TN mode (Twisted Nematic) mode active matrix type liquid crystal device, the liquid crystal is driven by an electric field applied between a TFT array substrate and a counter substrate.
In this liquid crystal device, as shown in FIG. 12, a TFT (thin film transistor) 30 for pixel switching is formed in each of a plurality of pixels formed in a matrix.
The source of T30 is electrically connected to the data line 6 to which the image signals S1, S2,... Are supplied. Also, T
The scanning line 3 is electrically connected to the gate of the FT 30 and the scanning signal G is pulsed to the scanning line 3 at a predetermined timing.
1, G2... Are applied in this order in a line-sequential manner. Further, in this liquid crystal device, it can be expressed as an equivalent circuit in which a liquid crystal capacitor 50 is formed between the TFT 30 and the counter electrode 21 held at the same potential in each pixel.

As shown in FIG. 13, a TFT array substrate used in such a liquid crystal device has a plurality of pixel electrodes 9 (in FIG. 13, the outline is shown by a solid line L9) for each pixel formed in a matrix. Are formed, and the data line 6 (the outline is shown by a dashed line L6 in FIG. 13) and the scanning line 3 (the outline is shown by a two-dot chain line L3 in FIG. 13) along the vertical and horizontal boundaries of the pixel electrode 9 respectively. Are shown) are formed. The data line 6 is electrically connected to a source region 31 of a TFT 30 formed of a semiconductor layer 100 (indicated by a dotted line L100 in FIG. 13) made of a polysilicon film or the like. Is electrically connected to the drain region 32 of FIG. Further, the scanning line 3 is T
It is formed so as to face the channel region 33 of the FT 30 and functions as a gate electrode.

The thus constructed TFT array substrate 10
Then, as shown in FIG. 14, an alignment film 16 on which a predetermined alignment process such as a rubbing process is performed is formed on the surface of the pixel electrode 9. The TFT array substrate 10 is disposed so as to face the transparent opposing substrate 20 with the liquid crystal 5 interposed therebetween. A counter electrode 21 is formed on the entire surface of the counter substrate 20, and an alignment film 22 on which a predetermined alignment process such as a rubbing process is performed is formed on the surface thereof. In the counter substrate 20, a light shielding film 23 called a black mask or a black matrix is formed in a non-opening region of the pixel. Here, the liquid crystal 5 receives the alignment regulating force from the alignment films 16 and 22 in a state where no electric field is applied from the pixel electrode 9 and is aligned in a 90 ° twisted state.

In the liquid crystal device constructed as described above, the scanning signals G1, G2,... Are applied to the scanning lines 3 in a pulsed manner in this order, and the switches of the TFTs 30 are closed for a certain period of time. Are supplied to the liquid crystal capacitor 50 of each pixel at a predetermined timing, the image signals S1, S2,.
Is held in a liquid crystal capacitor 50 formed between the pixel electrode 9 and the counter electrode 21 for a certain period. Here, the liquid crystal capacity 50
Since the liquid crystal 5 constituting the liquid crystal 5 modulates the incident light by changing the orientation and order of the molecular assembly according to the voltage level applied to each pixel, a predetermined display can be performed.

In such a liquid crystal device, a direction perpendicular to the TFT array substrate 10 and the counter substrate 20 (arrow B)
The liquid crystal 5 is driven by applying an electric field (longitudinal electric field) in the direction indicated by (), but there is a problem that the viewing angle is narrow.

[0008] In order to solve such problems,
2. Description of the Related Art In recent years, an IPS (in-plane SWI) that drives a liquid crystal by an electric field in a horizontal direction with respect to a substrate that holds the liquid crystal.
(Ching) mode liquid crystal devices have been developed.

In this liquid crystal device, basically, as shown in FIG. 15, a pixel switching TFT 30 is formed in each of a plurality of pixels formed in a matrix.
The source of the FT 30 is electrically connected to the data line 6 to which the image signals S1, S2,. Also,
The scanning line 3 is electrically connected to the gate of the TFT 30,
At a predetermined timing, the scanning signal G is pulsed to the scanning line 3.
1, G2... Are applied in this order in a line-sequential manner.

In this liquid crystal device, the equivalent circuit can be expressed as a liquid crystal capacitor 50 formed between the TFT 30 for each pixel and the common electrode 41 held at the same potential in each pixel. However, this common electrode 41
As shown in FIGS. 16 and 17, it is formed on the TFT array substrate 10 together with the TFT 30 and the like.

That is, as shown in FIG. 16, a TFT array substrate used in an IPS mode liquid crystal device has a plurality of pixel electrodes 9 for each pixel formed in a matrix.
(The outline is shown by a solid line L9 in FIG. 16). Further, at the vertical and horizontal boundaries of the region where the pixel electrode 9 is formed, the data line 6 (indicated by a dashed line L6 in FIG. 16) and the scanning line 3 (indicated by a two-dot chain line L3 in FIG. 16). Are shown) are formed. This T
In the FT array substrate as well, the data line 6 is electrically connected to the source region 31 of the TFT 30 formed from the semiconductor layer 100 made of a polysilicon film or the like (the outline is indicated by a dotted line L100 in FIG. 16). The electrode 9 is a TFT3
0 is electrically connected to the drain region 32. Also,
The scanning line 3 is formed so as to face the channel region 33 of the TFT 30, and functions as a gate electrode.

However, in the TFT array substrate 10 used for this liquid crystal device, the pixel electrode 9 has a comb-like shape bent at a plurality of positions, and the common electrode 41 (FIG. The outline is shown by a solid line L41 in FIG. Further, the common electrode 41 is connected to a common wiring 40 (FIG. 16) formed in parallel with the data line 6.
(The outline is shown by a dashed-dotted line L40). This common wiring 40 is kept at a constant potential.

In the TFT array substrate 10, as shown in FIG. 17, an alignment film 16 on which a predetermined alignment process such as a rubbing process is performed is formed on the surface of the pixel electrode 9.
The TFT array substrate 10 is disposed so as to face a transparent opposing substrate 20 with the liquid crystal 5 interposed therebetween. The opposing substrate 20 has an alignment film 22 and a light shielding film 23 formed thereon.
However, unlike the liquid crystal device described with reference to FIGS. 12, 13 and 14, no counter electrode is formed on the counter substrate 20.

In the liquid crystal device thus configured,
Scanning signals G1, G2, G3,.
Are applied line-sequentially in this order to close the switch of the TFT 30 for a certain period of time, so that the image signals S1, S2, S3... When written, the image signal S
1, S2, S3,... Are held in the liquid crystal capacitor 50 for a certain period.

At this time, if a liquid crystal 5 having a positive dielectric anisotropy is used and vertical alignment films are formed as the alignment films 16 and 22, an electric field is applied between the pixel electrode 9 and the common electrode 41. In a pixel where no is applied, the liquid crystal molecules remain in a vertical position with respect to the TFT array substrate 10, whereas an electric field applied between the pixel electrode 9 and the common electrode 41 is applied. In the pixel thus formed, the liquid crystal molecules form a horizontal electric field (arrow B) formed between the pixel electrode 9 and the common electrode 41.
(Indicated by (1)), the orientation is changed to a posture parallel to the TFT array substrate 10, and the long axis is directed to the pixel electrode 9 and the common electrode 41. Therefore, the presence or absence of voltage application for each pixel,
Alternatively, predetermined display can be performed by controlling the applied voltage level.

[0016]

However, in the conventional TN mode and IPS mode, fine gray scale control is difficult because gray scale is controlled only by electric fields in the vertical and horizontal directions on the substrate, respectively. In addition, conventional IP
The S-mode liquid crystal device has a problem that it is susceptible to a lateral electric field from an adjacent pixel because the alignment state of the liquid crystal is controlled using an electric field parallel to the substrate. Furthermore, in the conventional IPS mode, there is a problem that the ratio of the area of the pixel electrode to the area of the liquid crystal portion for controlling the alignment state is large, so that miniaturization is difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electro-optical device capable of easily performing gradation control and performing high-definition display.

[0018]

In order to solve the above-mentioned problems, in the electro-optical device according to the present invention, the first substrate and the second substrate for holding an electro-optical material between the substrates may be used. A first pixel electrode and a second pixel electrode for controlling the alignment state of the electro-optical material between pixel electrodes are formed adjacent to each other on the substrate, and the second substrate includes at least the first pixel electrode. A counter electrode is formed in a region corresponding to a region between the pixel electrode and the second pixel electrode.

In the electro-optical device according to the present invention, the first
When an electric field is applied between the first pixel electrode and the second pixel electrode on the side of the substrate, a horizontal electric field generated between the first pixel electrode and the second pixel electrode (a horizontal electric field is applied to the substrate). ) Or the oblique electric field changes the orientation of the electro-optical material,
The polarization characteristics of light passing through this electro-optic material change.
Therefore, if the presence or absence of the electric field or the strength of the electric field is controlled for each pixel, a predetermined display can be performed by modulating the light incident on the electro-optical material. Further, in the present invention, since the counter electrode is formed on the second substrate side, the electro-optical material located between the first pixel electrode and the second pixel electrode faces the first pixel electrode. The influence of the electric field between the electrodes and the electric field between the second pixel electrode and the counter electrode is also affected. That is, the electro-optical material is generated between the first pixel electrode and the counter electrode in addition to the influence of the horizontal electric field and the oblique electric field generated between the first pixel electrode and the second pixel electrode ( Also affected by the vertical electric field (electric field in the direction perpendicular to the substrate) generated between the second pixel electrode and the counter electrode (electric field in the direction perpendicular to the substrate). Therefore, as compared with a conventional IPS mode electro-optical device that drives an electro-optical material only by a horizontal electric field, there is an advantage that it is less affected by a horizontal electric field from an adjacent pixel. Further, the electro-optical material located near the first pixel electrode and the electro-optical material located near the second pixel electrode are determined by a combination of the potentials of the first pixel electrode, the second pixel electrode, and the counter electrode. There is an advantage that a delicate gradation display can be performed by changing the orientation state between.

In the present invention, the counter electrode may be formed, for example, on substantially the entire surface of the second substrate.

In the present invention, when the electro-optical device is driven by an active matrix, the first substrate includes:
A first data line, a second data line, and a scanning line are formed, and the first pixel electrode is connected to the first data line via a first pixel switching thin film transistor (hereinafter, referred to as TFT). And the second pixel electrode is electrically connected to the second data line and the scanning line via a second pixel switching TFT. .

In the present invention, it is preferable that both the first pixel electrode and the second pixel electrode have a comb shape. That is, the first pixel electrode includes:
The second pixel electrode has a planar shape with irregularities directed toward the second pixel electrode, and the second pixel electrode has a convex portion projecting into a concave portion of the first pixel electrode, or a convex portion of the first pixel electrode. It is preferable that the projection has a recess protruding inward. According to this structure, a region which substantially contributes to display, that is, an area where the first pixel electrode and the second pixel electrode face each other can be enlarged.

When the pixel size is small, it is preferable that the first pixel electrode and the second pixel electrode are formed in a strip shape and arranged in parallel. Since the liquid crystal in the vicinity of the first pixel electrode and the liquid crystal in the vicinity of the second pixel electrode can be independently modulated, two pixel displays can be obtained with one set of pixel electrodes.

In the present invention, at least one of the first substrate and the second substrate has a color filter overlapping a region corresponding to a region between the first pixel electrode and the second pixel electrode. Is preferably formed.

Further, the color filter may have different hues on the first pixel electrode side and the second pixel electrode side. With this configuration, different colors can be displayed near the first pixel electrode and near the second pixel electrode.

In the present invention, the counter electrode is formed of a conductive film having optical transparency, and the first pixel electrode and the second pixel electrode are each formed of a conductive film having light reflectivity. Is preferred. That is,
In the case of the transmissive type, when the pixel aperture ratio is reduced by forming two data lines or two TFTs for each pixel, the brightness of the display tends to decrease accordingly, but the reflection With the type, a bright display can be performed even if two data lines and two TFTs are formed for each pixel.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, an example in which the present invention is applied to a liquid crystal device which is a typical electro-optical device will be described. In the following description, portions having functions common to those of the liquid crystal device described with reference to FIGS. 12 to 17 are denoted by the same reference numerals.

[Embodiment 1] FIG. 1 is an equivalent circuit diagram schematically showing a basic structure of a liquid crystal device as an electro-optical device according to the present invention. FIG. 2 is an enlarged plan view showing some of pixel electrodes and pixel switching TFTs formed on the TFT array substrate of the liquid crystal device shown in FIG. FIG. 3 is a cross-sectional view when the liquid crystal device is cut at a position corresponding to the line II-II ′ in FIG.
In each of the drawings, the scale of each layer and each member is different so that each layer and each member have a size that can be recognized in the drawings. In addition, in order to prevent the held image signal from leaking, a storage capacitor may be added in parallel with the liquid crystal capacitor. FIGS. 1 and 2 show the characteristic points of the present invention clearly. FIG. 3 does not show the storage capacitor.

As shown in FIG. 1, in the liquid crystal device 1 of the present embodiment, each of a plurality of pixels formed in a matrix is provided with a first pixel switching TFT 30A and a second pixel switching TFT 30B. Are formed. Of the TFTs 30A and 30B, the source of the first pixel switching TFT 30A is connected to the image signal S1.
The first data line 6A to which A, S2A,... Are supplied is electrically connected. The scanning line 3 is electrically connected to the gate of the TFT 30A.
The scanning signals G1, G2,... Are applied to the scanning lines 3 in a pulsed manner in this order.

Also, a second pixel switching TFT
The source of 30B is electrically connected to a second data line 6B to which the image signals S1B, S2B... Are supplied. The scanning line 3 common to the TFT 30A is electrically connected to the gate of the TFT 30B.

In the liquid crystal device 1, in terms of an equivalent circuit, a liquid crystal capacitor 50 is formed between the TFT 30A and the TFT 30B in each pixel.
The counter electrode 21 held at the same potential in each pixel is also electrically connected. Note that, in the liquid crystal device 1 of the present embodiment, the liquid crystal capacitance 50 includes the image signals S1A, S2A... Applied via the TFT 30A and the image signals S1B, S2B. When a potential corresponding to the difference is applied,
In FIG. 1, the liquid crystal capacitance 50 is represented by three capacitors.

The TFT used in such a liquid crystal device 1
As shown in FIG. 2, the array substrate includes a first pixel electrode 9A (indicated by a solid line L9A in FIG. 2) and a second pixel electrode 9B for each pixel formed in a matrix.
(In FIG. 2, the outline is shown by a solid line L9B). Here, each of the first pixel electrode 9A and the second pixel electrode 9B has a comb shape. That is, the first pixel electrode 9 </ b> A has a planar shape with irregularities directed toward the second pixel electrode 9 </ b> B.
B is a protrusion projecting into the recess of the first pixel electrode 9A;
And a concave portion in which the convex portion of the first pixel electrode 9A protrudes inward. For this reason, the first pixel electrode 9A and the second
The area where the pixel electrode 9B faces is large.

Here, since the liquid crystal device 1 of this embodiment is of a reflection type, each of the pixel electrodes 9A and 9B is formed of a light-reflective conductive film such as an aluminum film.

Along the vertical and horizontal boundaries of the area where the pixel electrodes 9A and 9B are formed, the first data line 6A
(The outline is indicated by a dashed line L6A in FIG. 2), the second data line 6B (the outline is indicated by a dashed line L6B in FIG. 2), and the scanning line 3 (the dashed line L3 in FIG. 2).
Are shown).

The first data line 6A is electrically connected to a source region 31A of a TFT 30A formed of a semiconductor layer 100A made of a polysilicon film or the like (the outline is indicated by a dotted line L100A in FIG. 2). First pixel electrode 9
A is electrically connected to the drain region 32A of the TFT 30A. The scanning line 3 is formed so as to face the channel region 33A of the TFT 30A.
Function as a gate electrode.

The second data line 6B is electrically connected to a source region 31B of a TFT 30B formed from a semiconductor layer 100B made of a polysilicon film or the like (the outline is indicated by a dotted line L100B in FIG. 2). Second pixel electrode 9
B is electrically connected to the drain region 32B of the TFT 30B. The scanning line 3 is formed so as to face the channel region 33B of the TFT 30B.
Function as a gate electrode.

The TFT array substrate 10 constructed as described above
As shown in FIG. 3, for example, a quartz substrate, a glass substrate,
An insulating substrate 11 such as a silicon substrate is used as a base, and a base film 12 is formed on the surface thereof. The base film 12 has a function of preventing the surface of the glass substrate used as the insulating substrate 11 from being deteriorated due to roughness during polishing, contamination remaining after washing, and the like.

The pixel electrode 9 is provided on the TFT array substrate 10.
A and 9B are formed, and an alignment film 16 on which a predetermined alignment process such as a rubbing process is performed is formed on the surface side. The pixel electrodes 9A and 9B are formed from a light-reflective conductive film such as aluminum or the like.
For example, it is made of an organic thin film such as a polyimide thin film.

The pixel electrode 9 is provided on the TFT array substrate 10.
TFTs 30A and 30B for controlling switching of these pixel electrodes are formed at positions adjacent to A and 9B. In this embodiment, the TFTs 30A and 30B have a self-aligned structure, but these TFTs may have an LDD structure or an offset gate structure. Note that each of the semiconductor layers 100A, 10A
On the surface of OB, a gate insulating film 15 is formed, on which the scanning lines 3 are formed.

The first interlayer insulating film 1 is formed on the scanning lines 3.
4 and the second interlayer insulating film 17 are formed, and the first data line 6A and the second data line 6B formed on the surface of the first interlayer insulating film 14 are connected to the sources of the TFTs 30A and 30B via contact holes, respectively. It is electrically connected to the regions 31A and 31B. In contrast, the TFT 30A,
On the drain side of 30B, the drain regions 32A, 32B
On the other hand, the pixel electrodes 9A and 9B are connected to the relay conductive film 80A,
80B is relayed and electrically connected.

The TFT array substrate 10 constructed as described above
Are bonded to the counter substrate 20 via a predetermined gap,
The gap is filled with liquid crystal 5. The counter substrate 20 includes
A counter electrode (common electrode) 21 is formed over the entire surface, and an alignment film 22 on which a predetermined alignment process such as a rubbing process is performed is formed on the surface. Counter electrode 21
Is, for example, ITO (Indium Tin Oxid)
e) It is made of a transparent conductive thin film such as a film. The alignment film 22
It is made of an organic thin film such as a polyimide thin film. Therefore, the liquid crystal 5 receives the alignment regulating force from the alignment films 16 and 22 in a state where no electric field is applied from the pixel electrodes 9A and 9B, and is aligned in parallel with the substrate, for example.

On the opposite substrate 20, a light shielding film 23 called a black mask or a black matrix is formed in a non-opening region of each pixel. Therefore, incident light does not enter the channel regions 33A and 33B of the TFTs 30A and 30B from the side of the counter substrate 20. Further, the light-shielding film 23 has a function of improving contrast, preventing color mixture of color materials when a color filter is formed, and the like.

Since the liquid crystal device 1 of this embodiment is of a reflection type, a reflection sheet or the like is laminated on the outer surface of the TFT array substrate 10.

In the liquid crystal device 1 configured as described above,
By applying the scanning signals G1, G2,... To the scanning line 3 in a pulsed manner in this order, and simultaneously closing the switches of the TFTs 30A, 30B for a certain period of time, an image supplied from the first data line 6A is obtained. The signals S1A, S2A,.
Is applied to the first pixel electrode 9A, and the image signals S1B, S2B,... Supplied from the second data line 6B are applied.
Are applied to the second pixel electrode 9B, between the first pixel electrode 9A and the second pixel electrode 9B, the liquid crystal 5 has image signals S1A, S2A... And image signals S1B,
S2B... Are applied for a certain period. At this time, the electric field applied to the liquid crystal 5 is a horizontal electric field generated between the first pixel electrode 9A and the second pixel electrode 9B (horizontal electric field on the substrate / indicated by arrow A in FIG. 3) or oblique. Electric field. Here, the liquid crystal 5 constituting the liquid crystal capacitor 50 modulates the incident light by changing the orientation and order of the molecular assembly according to the voltage level applied to each pixel, and thus can perform a predetermined display.

As described above, the liquid crystal device 1 according to the present embodiment is driven basically in the same manner as in the IPS mode.
A counter electrode 21 is formed at 0, and the counter electrode 21 is kept at a constant potential. For this reason, the first pixel electrode 9A
The liquid crystal 5 located between the first pixel electrode 9B and the second pixel electrode 9B
The electric field between the pixel electrode 9A and the counter electrode 21 (indicated by an arrow B in FIG. 3), and the second pixel electrode 9B and the counter electrode 2
1 (shown by an arrow B in FIG. 3). That is, the liquid crystal 5 has the first pixel electrode 9A.
In addition to the influence of the horizontal electric field and the oblique electric field generated between the first pixel electrode 9A and the counter electrode 21B,
(An electric field in a direction perpendicular to the substrate) generated between the second pixel electrode 9B and the counter electrode 21 (an electric field in a direction perpendicular to the substrate). Will be. Therefore, as compared with the conventional IPS mode liquid crystal device that drives the liquid crystal only by the lateral electric field, there is an advantage that it is less affected by the lateral electric field from the adjacent pixels.

Since the liquid crystal device 1 is of a reflection type, a plurality of data lines 6A, 6B, 6C and a plurality of TFTs 30 are provided.
Even when the pixel aperture ratio is reduced by forming A, 30B, and 30C, a bright display can be performed.

Further, by combining the potentials of the first pixel electrode 9A, the second pixel electrode 9B and the counter electrode 21, the liquid crystal 5 located near the first pixel electrode 9A and the second
By changing the alignment state between the liquid crystal 5 and the liquid crystal 5 located near the pixel electrode 9B, it is possible to realize a delicate gradation display such as increasing the number of gradations.

This will be described with reference to FIGS. 4, 5 and 6.

FIG. 4 shows an equipotential line when the potential of the first pixel electrode 9A is +10 V, the potential of the second pixel electrode 9B is 0 V, and the potential of the counter electrode 21 is 0 V in the liquid crystal device. It is explanatory drawing which shows a direction and the light quantity distribution | emission which is emitted. FIG. 5 shows an equipotential line when the potential of the first pixel electrode 9A is 0 V, the potential of the second pixel electrode 9B is +10 V, and the potential of the counter electrode 21 is 0 V, the direction of the liquid crystal molecules, and the emission of the liquid crystal device. FIG. 5 is an explanatory diagram showing a light amount distribution to be performed. FIG.
Means that the potential of the first pixel electrode 9A is +
FIG. 9 is an explanatory diagram showing equipotential lines, directions of liquid crystal molecules, and distributions of emitted light amounts when the potential of the second pixel electrode 9B is +10 V, and the potential of the counter electrode 21 is 0 V.

In the embodiments shown in these figures, a liquid crystal 5 having a positive dielectric anisotropy is used, and alignment films 16 and 22 are used.
In a pixel in which no electric field is applied between the pixel electrode 9 and the common electrode 41, the liquid crystal molecules remain in a horizontal position with respect to the TFT array substrate 10 (dark state). In contrast, when an electric field is applied to the liquid crystal 5, the liquid crystal molecules change the direction of the long axis in a direction along the electric field (bright state).

That is, as shown in FIG. 4, when the potential of the first pixel electrode 9A is + 10V, the potential of the second pixel electrode 9B is 0V, and the potential of the counter electrode 21 is 0V, the first pixel electrode 9A In the vicinity, the liquid crystal 5 receives the combined effect of the potential of the second pixel electrode 9B and the potential of the counter electrode 21. As a result, the vicinity of the first pixel electrode 9A becomes bright while the second pixel electrode 9A becomes bright. Near the pixel electrode 9B, the liquid crystal 5
Is affected only by the potential of the first pixel electrode 9A, so that the vicinity of the second pixel electrode 9B is in a dark state.

On the other hand, as shown in FIG. 5, when the potential of the first pixel electrode 9A is 0V, the potential of the second pixel electrode 9B is + 10V, and the potential of the counter electrode 21 is 0V, the second Near the pixel electrode 9B, the liquid crystal 5 receives the combined influence of the potential of the first pixel electrode 9A and the potential of the counter electrode 21. As a result, the liquid crystal 5 becomes bright in the vicinity of the second pixel electrode 9B, In the vicinity of the first pixel electrode 9A, the liquid crystal 5 is only affected by the potential of the second pixel electrode 9A, so that the vicinity of the first pixel electrode 9A is in a dark state.

On the other hand, as shown in FIG. 6, the potential of the first pixel electrode 9A is + 10V, and the potential of the second pixel electrode 9B is + 10V.
When the potential of the counter electrode 21 is 10 V and the potential of the counter electrode 21 is 0 V, the liquid crystal 5 receives the combined effect of the potential of the second pixel electrode 9B and the potential of the counter electrode 21 near the first pixel electrode 9A. The area around the first pixel electrode 9A is in a bright state. Further, near the second pixel electrode 9B, the liquid crystal 5 receives the combined influence of the potential of the first pixel electrode 9A and the potential of the counter electrode 21. As a result, the vicinity of the second pixel electrode 9B is bright. State. However, the first pixel electrode 9
A and the vicinity of the second pixel electrode 9B are in a dark state.

As described above, in the liquid crystal device 1 of the present embodiment, the first pixel electrode 9A is determined by the combination of the potentials of the first pixel electrode 9A, the second pixel electrode 9B, and the counter electrode 21.
By changing the alignment state between the liquid crystal 5 located near and the liquid crystal 5 located near the second pixel electrode 9B,
Delicate gradation display can be performed.

[Embodiment 2] FIG. 7 shows a pixel electrode and a pixel switching TFT formed on a TFT array substrate of a liquid crystal device according to Embodiment 2 of the present invention.
It is a top view which expands and shows some of them. 8 and 9 are a cross-sectional view of the liquid crystal device taken along a line corresponding to the line VIIA-VIIA 'in FIG. 2 and a liquid crystal device taken along a line corresponding to the line VIIB-VIIB' in FIG. It is sectional drawing at the time. In each of the drawings, the scale of each layer and each member is different so that each layer and each member have a size that can be recognized in the drawings.
Further, in order to prevent the held image signal from leaking, a storage capacitor may be added in parallel with the liquid crystal capacitor, but FIGS. 7 and 8 are used to clearly illustrate the features of the present invention. FIG. 9 does not show the storage capacitor.

Since the liquid crystal device of the present embodiment is also basically represented by the equivalent circuit shown in FIG. 1, the description of the overall configuration is omitted, but the TFT array substrate used in the liquid crystal device of the present embodiment includes As shown in FIG. 7, a comb-shaped first pixel electrode 9A (in FIG. 7, the outline is shown by a solid line L9A)
And a comb-shaped second pixel electrode 9B (solid line L9B in FIG. 7).
And the outline is shown). Along the vertical and horizontal boundaries of the region where the pixel electrode 9A is formed, a first data line 6A (in FIG. 7, the outline is indicated by a dashed line L6A) and a second data line 6B (see FIG. 7). 7, the outline is indicated by a dashed line L6B), and the scanning line 3 (the outline is indicated by a two-dot chain line L3 in FIG. 7).

The first pixel electrode 9A is formed on the side opposite to the side on which the first pixel electrode 9A is formed with respect to the second pixel electrode 9B.
Another first pixel electrode 9C (third pixel electrode / outlined by a solid line L9C in FIG. 7) is formed in a comb-like shape in line symmetry with the pixel electrode 9A.
Are formed along the vertical and horizontal boundaries of the area where the first data line is formed (third data line / indicated by a dashed line L6C in FIG. 7) and the second data line 6C. In this state, the line 6B and the scanning line 3 are formed.

The first data line 6A is, as in the first embodiment, a semiconductor layer 100A made of a polysilicon film or the like (FIG. 7).
In this case, the first pixel electrode 9A is electrically connected to the drain region 32A of the TFT 30A, and the source region 31A of the TFT 30A is electrically connected to the drain region 32A of the TFT 30A. The scanning line 3 is
It is formed so as to face the channel region 33A of the TFT 30A, and functions as a gate electrode of the TFT 30A.

As in the first embodiment, the second data line 6B is connected to a semiconductor layer 100B made of a polysilicon film or the like (FIG. 7).
In this case, the second pixel electrode 9B is electrically connected to the drain region 32B of the TFT 30B, and the second pixel electrode 9B is electrically connected to the source region 31B of the TFT 30B. The scanning line 3 is
The TFT 30B is formed so as to face the channel region 33B, and functions as a gate electrode of the TFT 30B.

Further, another first data line 6C
Is a semiconductor layer 100C made of a polysilicon film or the like (FIG. 7)
In this case, the first pixel electrode 9C is electrically connected to the source region 31C of the TFT 30C formed by the TFT 30C.
Is electrically connected to the drain region 32C. Also,
The scanning line 3 is formed so as to face the channel region 33C of the TFT 30C, and functions as a gate electrode of the TFT 30C.

The TFT array substrate 10 constructed as described above
As shown in FIGS. 8 and 9, an insulating substrate 11 such as a quartz substrate, a glass substrate, or a silicon substrate is used as a base, and a base film 12 is formed on the surface thereof. Also, T
Pixel electrodes 9A, 9B, and 9C are formed on the FT array substrate 10, and an alignment film 16 that has been subjected to a predetermined alignment process such as a rubbing process is formed on the surface side thereof.

In this embodiment, since the liquid crystal device 1 is of a reflection type, the first pixel electrodes 9A, 9B, 9C
Is formed of a light-reflective conductive film such as aluminum. The alignment film 16 is made of, for example, an organic thin film such as a polyimide thin film.

The TFT array substrate 10 has pixel electrodes 9
A, 9B, 9C, a pixel switching TFT 30 for switching control of these pixel electrodes
A, 30B and 30C are formed. Also in this embodiment, the gate insulating film 15 is formed on the surface of each of the semiconductor layers 100A, 100B, and 10C, and the scanning line 3 is formed thereon. A first interlayer insulating film 14 and a second interlayer insulating film 17 are formed on the scanning line 3, and the data lines 6 A, 6 B, 6 C formed on the surface of the first interlayer insulating film 4 are respectively connected via contact holes. TFT 30A, 30B, 3
0C are electrically connected to the source regions 31A, 31B, and 31C. In contrast, the TFTs 30A, 30B, 3
On the drain side of 0C, the drain regions 32A, 32B,
The pixel electrode 9A, 9B, 9C is connected to the 32C via the relay conductive films 80A, 80B, 80C.

The TFT array substrate 10 thus configured
Is bonded to the opposing substrate 20 via a predetermined gap as in the first embodiment, and the gap is filled with the liquid crystal 5.

In this embodiment, since the liquid crystal device 1 is of a reflection type, a reflection sheet or the like is laminated on the outer surface of the TFT array substrate 10.

Here, a counter electrode (common electrode) 21 is formed on the entire surface of the counter substrate 20, and an alignment film 22 on which a predetermined alignment process such as a rubbing process is performed is formed on the surface thereof. I have. The counter electrode 21 is made of, for example, IT
It is made of a transparent conductive thin film such as an O film. The alignment film 22 is made of an organic thin film such as a polyimide thin film. Therefore, the liquid crystal 5
Receives an alignment regulating force from the alignment films 16 and 22 in a state where no electric field is applied from the pixel electrodes 9A, 9B and 9C,
For example, they will be oriented parallel to the substrate.

In the counter substrate 20, a light shielding film 23 called a black mask or a black matrix is formed in a non-opening area of each pixel.

Further, in this embodiment, the opposite substrate 20 includes
Of the region between the pixel electrodes 9A and 9B, a red color filter 7R is formed in a region facing the vicinity of the pixel electrode 9A, and a blue color filter 7B is formed in a region facing the vicinity of the pixel electrode 9B. The counter substrate 20 has a pixel electrode 9 out of a region between the pixel electrodes 9B and 9C.
A blue color filter 7B is formed in a region facing near B, and a green color filter 7G is formed in a region facing near the pixel electrode 9B.

In the liquid crystal device 1 constructed as described above, the scanning signals are applied to the scanning lines 3 in a pulsed manner in this order and the TFTs 30A, 30B, and 30C are simultaneously turned off for a certain period of time, so that the data is turned off. Line 6
When the image signals supplied from A, 6B, and 6C are applied to the pixel electrodes 9A, 9B, and 9C, respectively, a potential corresponding to the potential difference between the pixel electrodes 9A and 9B is applied across the liquid crystal 5 between the pixel electrodes 9A and 9B. An electric field (indicated by an arrow A) is applied for a certain period, and a potential corresponding to the potential difference between the pixel electrodes 9B and 9C is also applied to the liquid crystal 5 between the pixel electrodes 9B and 9C as a horizontal electric field (indicated by an arrow A). It is applied for a certain period.

As described above, the liquid crystal device 1 of the present embodiment is driven basically in the same manner as in the IPS mode,
A counter electrode 21 is formed at 0, and the counter electrode 21 is kept at a constant potential. Therefore, the pixel electrodes 9A, 9B
Is located between the pixel electrode 9A and the counter electrode 2A.
1 (shown by an arrow B in FIG. 8) and the electric field between the pixel electrode 9B and the counter electrode 21 (shown by an arrow B in FIG. 8). Further, the pixel electrode 9B,
9C, an electric field between the pixel electrode 9B and the counter electrode 21 (indicated by an arrow B in FIG. 9) and an electric field between the pixel electrode 9C and the counter electrode 21 (see FIG. 9). Arrow B
)).

Therefore, in the liquid crystal device 1 of the present embodiment, FIG.
As described with reference to FIGS. 5 and 6, the pixel electrodes 9A,
The liquid crystal 5 and the pixel electrode 9 located near the pixel electrode 9A are determined by the combination of the potentials of the counter electrodes 21 and 9B, 9C.
The alignment states of the liquid crystal 5 located near B and the liquid crystal 5 located near the pixel electrode 9C can be respectively changed. Moreover, since the color filters 7R, 7G, and 7B are formed so as to face these regions, a predetermined color can be displayed in each region.

Further, since the liquid crystal 5 is affected not only by the horizontal electric field but also by the vertical electric field, compared with the conventional IPS mode liquid crystal device which drives the liquid crystal 5 only by the horizontal electric field, the horizontal electric field of the adjacent pixel is reduced. There is also the advantage of being less affected.

Further, since the liquid crystal device 1 is of a reflection type,
A plurality of data lines 6A, 6B, 6C and a plurality of TFTs 30
Even when the pixel aperture ratio is reduced by forming A, 30B, and 30C, a bright display can be performed.

[Other Embodiments] In each of the above embodiments, the reflection type liquid crystal device has been described as an example, but the TFT array substrate 10, the counter substrate 20, the counter electrode 2
1. If the first pixel electrode 9A and the second pixel electrode 9B have a light transmission property, a transmission type liquid crystal device can be formed. That is, the counter electrode 21 and the first
For the pixel electrode 9A and the second pixel electrode 9B,
What is necessary is just to form with an ITO film etc.

[Overall Configuration of Electro-Optical Device] FIGS. 10 and 11 show the overall configuration of the liquid crystal device 1 configured as described above.
This will be described with reference to FIG. FIG. 10 shows a TFT array substrate 10
FIG. 11 is a plan view as viewed from the side of the counter substrate 20 together with the components formed thereon, and FIG.
It is sectional drawing.

In the liquid crystal device 1 shown in FIG.
On the array substrate 10, a sealing material 52 is provided along the edge thereof.
Is provided with a light-shielding film 53 as a frame that defines the periphery of the image display area made of the same or different material as the light-shielding film 23 (see FIGS. 3 and 8).

In a region outside the sealing material 52, a data line driving circuit 1 for driving a data line by supplying an image signal to the data line (see FIGS. 2 and 7) at a predetermined timing.
01 and the mounting terminals 102 are provided along one side of the TFT array substrate 10, and the scanning lines that drive the scanning lines 3 by supplying the scanning signals to the scanning lines 3 (see FIGS. 2 and 7) at a predetermined timing. The drive circuit 104 is provided along two sides adjacent to the one side. If the delay of the scanning signal supplied to the scanning line 3 does not matter, it goes without saying that the scanning line driving circuit 104 may be provided on only one side. Further, the data line driving circuits 101 may be arranged on both sides along the side of the image display area. For example, the odd-numbered data lines supply image signals from a data line driving circuit disposed along one side of the image display area, and the even-numbered data lines extend along the opposite side of the image display area. The image signal may be supplied from the data line driving circuit provided. If the data lines are driven in a comb-tooth shape in this manner, the area occupied by the data line driving circuit 101 can be expanded, so that a complicated circuit can be formed.

On one remaining side of the TFT array substrate 10, a plurality of wirings 105 for connecting between the scanning line driving circuits 104 provided on both sides of the image display area are provided. In at least one of the corners of the opposing substrate 20, a conductive material 106 for establishing electric conduction between the TFT array substrate 10 and the opposing substrate 20 is provided. Then, as shown in FIG. 11, the opposite substrate 20 having substantially the same contour as the sealing material 52 shown in FIG. 10 is fixed to the TFT array substrate 10 by the sealing material 52.

On the TFT array substrate 10, in addition to the data line driving circuit 101, the scanning line driving circuit 104, etc., a sampling circuit for applying image signals to a plurality of data lines at a predetermined timing, and a plurality of Forming a precharge circuit for supplying a precharge signal of a predetermined voltage level to a data line prior to an image signal, an inspection circuit for inspecting the quality, defects, and the like of the liquid crystal device during manufacture or shipping. Is also good.

In the liquid crystal device 1, instead of providing the data line driving circuit 101 and the scanning line driving circuit 104 on the TFT array substrate 10, for example, TAB (Tape)
A driving LSI mounted on an Automated Bonding substrate may be electrically and mechanically connected via an anisotropic conductive film provided on the periphery of the TFT array substrate 10. Further, the liquid crystal device 1
, A polarizing film, a retardation film, a polarizing plate, and the like are arranged in a predetermined direction according to the normally white mode / normally black mode.

[0081]

As described above, in the electro-optical device according to the present invention, when an electric field is applied between the first pixel electrode and the second pixel electrode on the first substrate side, the same as in the IPS mode The orientation state of the electro-optical material changes due to a horizontal electric field (an electric field in a horizontal direction on the substrate) or an oblique electric field generated between the first pixel electrode and the second pixel electrode, and the electro-optical material passes through the electro-optical material. The polarization characteristics of the light change. Also, the second
Since the opposing electrode is formed on the substrate side of the first pixel electrode, the electro-optical material is affected by the lateral electric field and the oblique electric field generated between the first pixel electrode and the second pixel electrode, and the first pixel Influence of the vertical electric field (electric field in the direction perpendicular to the substrate) generated between the electrode and the counter electrode (electric field in the direction perpendicular to the substrate) and between the second pixel electrode and the counter electrode. Will also receive. Therefore, compared to an electro-optical device that drives an electro-optical material only by a lateral electric field, it is less susceptible to a lateral electric field from an adjacent pixel. Further, the electro-optical material located near the first pixel electrode and the electro-optical material located near the second pixel electrode are determined by a combination of the potentials of the first pixel electrode, the second pixel electrode, and the counter electrode. By changing the orientation state between and, fine gradation control can be performed. Further, since two display states can be obtained in one pixel, there is an advantage that miniaturization is possible as compared with the IPS mode.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram schematically showing a basic configuration of a liquid crystal device as an electro-optical device according to a first embodiment of the present invention.

2 is an enlarged plan view showing some of pixel electrodes and pixel switching TFTs formed on a TFT array substrate of the liquid crystal device shown in FIG. 1. FIG.

FIG. 3 is a cross-sectional view when the liquid crystal device is cut at a position corresponding to line II-II ′ in FIG.

FIG. 4 is a diagram illustrating an equipotential line when the potential of a first pixel electrode is +10 V, the potential of a second pixel electrode is 0 V, and the potential of a counter electrode is 0 V in the liquid crystal device illustrated in FIG.
FIG. 3 is an explanatory diagram showing a distribution of the amount of light emitted from each region.

FIG. 5 is a diagram illustrating an equipotential line when the potential of a first pixel electrode is 0 V, the potential of a second pixel electrode is +10 V, and the potential of a counter electrode is 0 V in the liquid crystal device illustrated in FIG.
FIG. 3 is an explanatory diagram showing a distribution of the amount of light emitted from each region.

FIG. 6 illustrates a liquid crystal device illustrated in FIG. 1 in which the potential of a first pixel electrode is +10 V, the potential of a second pixel electrode is +10 V,
FIG. 4 is an explanatory diagram showing equipotential lines when the potential of a counter electrode is 0 V, directions of liquid crystal molecules, and distributions of light amounts emitted from respective regions.

FIG. 7 shows a TFT of a liquid crystal device according to Embodiment 2 of the present invention.
It is a top view which expands and shows some of the pixel electrode and TFT for pixel switching formed in the array substrate.

8 is a cross-sectional view when the liquid crystal device is cut at a position corresponding to line VIIA-VIIA 'in FIG.

9 is a cross-sectional view when the liquid crystal device is cut at a position corresponding to line VIIB-VIIB 'in FIG.

FIG. 10 is a plan view of a TFT array substrate of a liquid crystal device together with components formed thereon viewed from a counter substrate side.

FIG. 11 is a sectional view taken along line XX ′ of FIG. 10;

FIG. 12 is an equivalent circuit diagram schematically showing a basic configuration of a conventional TN mode liquid crystal device.

13 shows a pixel electrode and a pixel switching TF formed on a TFT array substrate of the liquid crystal device shown in FIG.
It is a top view which expands and shows some of T.

14 is a cross-sectional view when the liquid crystal device is cut at a position corresponding to line XIII-XII ′ in FIG.

FIG. 15 is an equivalent circuit diagram schematically showing a basic configuration of a conventional IPS mode liquid crystal device.

16 shows a pixel electrode and a pixel switching TF formed on a TFT array substrate of the liquid crystal device shown in FIG.
It is a top view which expands and shows some of T.

17 is a cross-sectional view when the liquid crystal device is cut at a position corresponding to line XVI-XVI ′ in FIG.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal device (electro-optical device) 5 liquid crystal (electro-optical material) 6A, 6C, 6C data line 7R, 7G, 7B color filter 9A, 9B, 9C pixel electrode 10 TFT array substrate (first substrate) 16, 22 orientation Film 20 Counter substrate (second substrate) 30A, 30B, 30C TFT

Continued on the front page F term (reference) 2H091 FA03Y FA14Y FA35Y GA02 GA03 HA06 LA30 2H092 GA14 HA04 HA05 JA25 JB42 KA05 NA01 PA08 PA09 QA06 5C094 AA05 BA03 BA43 CA19 CA23 CA25 EA03 EA04 EA07 ED02 ED11 FA04 BB12 CC09

Claims (7)

[Claims] A first substrate for holding an electro-optical material between the substrates; a first substrate for controlling an alignment state of the electro-optical material between pixel electrodes;
And a second pixel electrode are formed adjacent to each other, and the second substrate has at least an opposing region opposing a region corresponding to a region between the first pixel electrode and the second pixel electrode. An electro-optical device comprising an electrode. 2. The electro-optical device according to claim 1, wherein the counter electrode is formed on substantially the entire surface of the second substrate. 3. The first substrate according to claim 1, wherein a first data line, a second data line, and a scanning line are formed on the first substrate. The first pixel line is electrically connected to the first data line and the scan line via one pixel switching thin film transistor, and the second pixel electrode is electrically connected to the second pixel switching thin film transistor via the second pixel switching thin film transistor. An electro-optical device electrically connected to a data line and the scanning line. 4. The method according to claim 1, wherein
The first pixel electrode has a planar shape with concavities and convexities directed toward the second pixel electrode, and the second pixel electrode has a convex portion protruding into a concave portion of the first pixel electrode; Alternatively, the electro-optical device is provided with a concave portion in which the convex portion of the first pixel electrode protrudes inward. 5. The method according to claim 1, wherein
A color filter is formed on at least one of the first substrate and the second substrate, the color filter overlapping a region facing between the first pixel electrode and the second pixel electrode. Electro-optical device characterized. 6. The electro-optical device according to claim 5, wherein the color filters have different hues on the first pixel electrode side and the second pixel electrode side. 7. The method according to claim 1, wherein
The counter electrode is formed of a conductive film having optical transparency, and both the first pixel electrode and the second pixel electrode are formed of a conductive film having light reflectivity. Electro-optical device.