JP2003228073A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high display quality liquid crystal display device having a wide viewing characteristic. <P>SOLUTION: A 1st substrate is provided with a pixel electrode, a switching element, and a bus line 18 arranged in each pixel area on the liquid crystal layer side, and a 2nd substrate is provided with a counter electrode faced to the pixel electrode. The pixel electrode 14 has a plurality of openings 14a and an inner substance part 14b consisting of a plurality of unit inner substance parts 14b', and in each pixel area, the liquid crystal layer is brought into the vertical alignment state when voltage is applied thereto, and when voltage is not applied thereto, an oblique electric field generated in the edge parts of a plurality of the opening parts 14a in the pixel electrode forms a plurality of liquid crystal domains each of which is brought into the radially inclined alignment state in a plurality of the openings 14a and the inner substance parts 14b. In each pixel area, among a plurality of the opening parts 14a of the pixel electrode, at least one of the opening parts 14a positioned between two pieces of the unit inner substance parts 14b' adjacent to the bus line 18 and next to a plurality of the unit inner substance parts 14b' is superposed on the bus line 18. <P>COPYRIGHT: (C)2003,JPO

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 more particularly to a liquid crystal display device having a wide viewing angle characteristic and performing high quality display.

[0002]

2. Description of the Related Art In recent years, a thin and lightweight liquid crystal display device has been used as a display device used for a display of a personal computer or a display section of a portable information terminal device.
However, conventional twisted nematic type (TN
Type) and super twisted nematic type (STN type) liquid crystal display devices have the drawback of having a narrow viewing angle, and various technological developments have been made to solve this.

As a typical technique for improving the viewing angle characteristics of a TN type or STN type liquid crystal display device, there is a system of adding an optical compensation plate. As another method, there is a lateral electric field method in which an electric field in the horizontal direction with respect to the surface of the substrate is applied to the liquid crystal layer. This lateral electric field type liquid crystal display device has been mass-produced in recent years and has attracted attention. Further, as another technique, a nematic liquid crystal material having a negative dielectric anisotropy is used as a liquid crystal material, and a vertical alignment film is used as an alignment film.
mation of vertical aligned phase). this is,
Voltage controlled birefringence (ECB: electrically controlled bire)
fringence), which controls the transmittance by utilizing the birefringence of liquid crystal molecules.

However, although the horizontal electric field method is one of the effective methods for widening the viewing angle, a stable production is difficult because the production margin in the manufacturing process is remarkably narrower than that of the normal TN type. There is a problem. This is because the unevenness of the gap between the substrates and the deviation of the transmission axis (polarization axis) of the polarizing plate with respect to the alignment axis of the liquid crystal molecules have a great influence on the display brightness and the contrast ratio. , For stable production,
Further technical development is needed.

Further, in order to perform uniform display without display unevenness in the DAP type liquid crystal display device, it is necessary to control the alignment. As a method of controlling the alignment, there is a method of carrying out the alignment treatment by rubbing the surface of the alignment film. However, when the rubbing treatment is applied to the vertical alignment film, rubbing streaks are likely to occur in the displayed image, which is not suitable for mass production.

On the other hand, as a method for controlling the alignment without performing the rubbing treatment, a method is used in which a slit (opening) is formed in an electrode to generate an oblique electric field and the oblique electric field controls the alignment direction of liquid crystal molecules. Have also been devised (see, for example, Patent Documents 1 and 2). However, as a result of examination by the inventors of the present application, in the method disclosed in the above publication, the alignment state of the region of the liquid crystal layer corresponding to the opening of the electrode is not defined, and the continuity of alignment of liquid crystal molecules is sufficient. In addition, it is difficult to obtain a stable alignment state over the entire picture element, resulting in a rough display.

Therefore, some of the inventors of the present application, together with others, form a predetermined electrode structure including an opening portion and a solid portion on one of a pair of electrodes facing each other with a liquid crystal layer interposed therebetween, and the opening portion is formed. We proposed a method of forming a plurality of liquid crystal domains with radial tilt alignment in these openings and solid parts by an oblique electric field generated at the edge part of the (Japanese Patent Application No. 2000-2.
44648).

[0008]

[Patent Document 1] JP-A-6-301036

[Patent Document 2] Japanese Patent Laid-Open No. 2000-47217

[0009]

However, the present inventor has found that the display quality may not be sufficiently improved only by providing the electrode structure as disclosed in the above application. This problem is caused by an electric field generated near the edge of the bus line (wiring group) that exerts an alignment control force that does not match the alignment control force of the oblique electric field generated at the edge of the opening. To do.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device having wide viewing angle characteristics and high display quality.

[0011]

A liquid crystal display device according to the present invention comprises a first substrate, a second substrate, the first substrate and the second substrate.
A liquid crystal layer provided between the substrate and a plurality of picture element regions for displaying, and the first substrate is provided on the liquid crystal layer side for each of the plurality of picture element regions. The pixel electrode, a switching element electrically connected to the pixel electrode, and a bus line including a gate bus line and a source bus line electrically connected to the switching element, The substrate has a counter electrode facing the picture element electrode via the liquid crystal layer, the picture element electrode has a plurality of openings, and a solid part consisting of a plurality of unit solid parts, In each of the plurality of picture element regions, the liquid crystal layer is in a vertical alignment state when a voltage is not applied between the picture element electrode and the counter electrode, and the picture element electrode and the counter electrode are opposed to each other. When a voltage is applied between the electrodes, A plurality of liquid crystal domains each having a radial tilt alignment state are formed in the plurality of openings and the solid portion by an oblique electric field generated at the edges of the plurality of openings, and the liquid crystal domains are changed depending on the applied voltage. A liquid crystal display device that performs display by changing the alignment state of the plurality of liquid crystal domains, wherein in each of the plurality of pixel regions, the bus line among the plurality of openings of the pixel electrode is provided. And at least one of the openings located between two adjacent unit solid parts of the plurality of unit solid parts has a configuration overlapping with the bus line, whereby the above-mentioned object is achieved. Is achieved.

Alternatively, the liquid crystal display device according to the present invention is
A first substrate, a second substrate, and a liquid crystal layer provided between the first substrate and the second substrate, and having a plurality of picture element regions for displaying, the first substrate On the liquid crystal layer side, a pixel electrode provided for each of the plurality of pixel regions,
A switching element electrically connected to the pixel electrode; and a bus line including a gate bus line and a source bus line electrically connected to the switching element, wherein the second substrate is the pixel element. The pixel electrode has a counter electrode facing the electrode through the liquid crystal layer, and the pixel electrode has a plurality of openings and a plurality of units each surrounded by at least a part of the plurality of openings. A liquid crystal display device having a solid part consisting of a real part, wherein the liquid crystal layer is in a vertical alignment state when a voltage is not applied between the pixel electrode and the counter electrode, In each of the plurality of picture element regions, among the plurality of openings of the picture element electrode, located close to the bus line and between two adjacent unit solid portions of the plurality of unit solid portions. At least one of the openings Has a structure overlapping with the bus line, the object is met.

The at least one opening overlapping the bus line preferably includes at least an opening near the gate bus line.

Of the plurality of openings of the picture element electrode,
All of the openings adjacent to the gate bus line may overlap with the bus line.

The at least one opening overlapping with the bus line may further include an opening near the source bus line.

At least some of the plurality of openings have substantially the same shape and size, and form at least one unit cell arranged to have rotational symmetry. It is preferable to have

The shape of each of the at least some of the plurality of openings preferably has rotational symmetry.

Each of the at least some of the plurality of openings may be substantially circular.

Each of the plurality of unit solid portions may have a substantially circular shape.

In each of the plurality of picture element regions,
It is preferable that the total area of the plurality of openings of the picture element electrode be smaller than the area of the solid part of the picture element electrode.

A projection is further provided inside each of the plurality of openings, and the cross-sectional shape of the projection in the in-plane direction of the substrate is the same as the shape of the plurality of openings. The side surface may have an alignment regulating force in the same direction as the alignment regulating direction by the oblique electric field with respect to the liquid crystal molecules of the liquid crystal layer.

Another liquid crystal display device according to the present invention comprises a first substrate, a second substrate, and a liquid crystal layer provided between the first substrate and the second substrate, and is for displaying. The first substrate has a plurality of picture element regions, the first substrate is provided on the liquid crystal layer side, the picture element electrodes provided for the plurality of picture element regions, and the switching element electrically connected to the picture element electrodes. And a bus line including a gate bus line and a source bus line electrically connected to the switching element,
The second substrate has a counter electrode facing the picture element electrode via the liquid crystal layer, and the picture element electrode has a plurality of openings and a solid portion. In each of the regions, the liquid crystal layer has a vertical alignment state when a voltage is not applied between the picture element electrode and the counter electrode, and between the picture element electrode and the counter electrode. When a voltage is applied, the alignment is regulated by an oblique electric field generated at the edge portions of the plurality of openings of the pixel electrode, a liquid crystal display device, in each of the plurality of pixel regions, At least one edge of the gate bus line and the source bus line is configured to be covered by the solid portion of the picture element electrode, whereby the above object is achieved.

In each of the plurality of picture element regions,
At least the edge of the gate bus line is preferably covered with the solid portion of the pixel electrode.

Further, in each of the plurality of picture element regions, both edges of the gate bus line and the source bus line may be covered by the solid portion of the picture element electrode.

The solid portion of the picture element electrode is composed of a plurality of unit solid portions, and the liquid crystal layer is provided between the picture element electrode and the counter electrode in each of the plurality of picture element regions. When a voltage is applied, the oblique electric field generated at the edges of the plurality of openings of the pixel electrode causes a plurality of radial inclined alignment states in the plurality of openings and the solid portion, respectively. The liquid crystal domain may be formed, and the display may be performed by changing the alignment state of the plurality of liquid crystal domains according to the applied voltage.

In each of the plurality of picture element regions,
Of the plurality of openings of the pixel electrode, adjacent to the bus line and adjacent to the plurality of unit solid portions 2
At least one of the openings located between the two unit solid parts may overlap the bus line.

When a voltage is applied between the picture element electrode and the counter electrode, the liquid crystal layer has a radial tilt alignment state in the solid portion near the bus line due to the oblique electric field. A structure may be used in which a part of the liquid crystal domain is formed.

The operation will be described below.

In the liquid crystal display device of the present invention, the picture element electrode for applying a voltage to the liquid crystal layer in the picture element region has a plurality of openings (a part of the electrode where no conductive film exists) and a solid part (electrode). , A portion other than the opening, and a portion where the conductive film exists). The solid portion has a plurality of unit solid portions, each of which is substantially surrounded by the opening, and is typically formed of a continuous conductive film. The liquid crystal layer has a vertical alignment state when no voltage is applied, and when a voltage is applied, a plurality of liquid crystal domains that have a radial tilt alignment state are formed by an oblique electric field generated at the edge of the opening of the pixel electrode. Form. Typically, the liquid crystal layer is made of a liquid crystal material having negative dielectric anisotropy, and its alignment is regulated by vertical alignment films provided on both sides thereof.

The liquid crystal domains formed by this oblique electric field are formed in the regions corresponding to the openings and solid portions of the picture element electrodes, and the alignment state of these liquid crystal domains changes according to the voltage to display an image. To do. Since each liquid crystal domain has an axially symmetric orientation, the viewing angle dependence of display quality is small, and wide viewing angle characteristics are provided.

Furthermore, since the liquid crystal domain formed in the opening and the liquid crystal domain formed in the solid portion are formed by the oblique electric field generated at the edge of the opening,
They are alternately formed adjacent to each other, and the alignment of liquid crystal molecules between adjacent liquid crystal domains is essentially continuous. Therefore, the disclination line is not generated between the liquid crystal domain formed in the opening and the liquid crystal domain formed in the solid portion, the display quality is not deteriorated thereby, and the stability of the alignment of the liquid crystal molecules is not caused. Is also high.

In the liquid crystal display device of the present invention, since the liquid crystal molecules have the radial tilt alignment not only in the region corresponding to the solid part of the pixel electrode but also in the region corresponding to the opening, the above-mentioned conventional method is adopted. Compared to a liquid crystal display device, the continuity of alignment of liquid crystal molecules is high, a stable alignment state is realized, and a uniform display without roughness can be obtained. In particular, in order to realize good response characteristics (fast response speed), it is necessary to apply an oblique electric field for controlling the alignment of liquid crystal molecules to many liquid crystal molecules, and for that purpose, openings (edge portions) are required. It is necessary to form many. In the liquid crystal display device of the present invention, since a liquid crystal domain having a stable radial tilt alignment is formed corresponding to the opening, even if a large number of openings are formed in order to improve the response characteristics, the display quality associated therewith is increased. Can be suppressed (the occurrence of roughness) can be suppressed.

However, only by providing the electrode structure as described above, the display quality cannot be sufficiently improved depending on the relative positional relationship between the opening of the pixel electrode and the edge of the bus line (wiring group). Sometimes.

Since a predetermined signal (voltage) for driving the liquid crystal display device is applied to the bus line of the liquid crystal display device, an electric field is generated between the bus line and the counter electrode. Therefore, an oblique electric field is generated in the vicinity of the edge of the bus line, but the alignment restriction force due to this oblique electric field does not match the alignment restriction force due to the oblique electric field generated at the edge of the opening. Therefore, when the liquid crystal domain formed in the opening close to the bus line is subjected to the alignment regulating force due to the oblique electric field near the edge of the bus line, the alignment is disturbed, and the state becomes a distorted radial tilt alignment state. In addition, since the adjacent liquid crystal domains try to maintain the continuity of alignment with each other, the above-mentioned alignment disorder also affects the alignment of the adjacent liquid crystal domains, that is, the liquid crystal domains of the adjacent unit solid parts. The alignment of the liquid crystal domains in the adjacent unit solid parts is also disturbed.

A liquid crystal domain in which the orientation is disturbed and has a distorted radial tilted orientation is easily broken because the orientation stability is low, and it takes a long time for the orientation to reach a steady state when a voltage is applied. Therefore, the disordered orientation as described above causes a decrease in response speed (deterioration of response characteristics).

Further, the liquid crystal domain formed in the pixel region becomes a steady state in the distorted radial tilt alignment state in which the alignment is disturbed as described above. An afterimage phenomenon in which the previous image remains may occur when a signal for switching is input. This is because if the alignment state of the liquid crystal layer differs between the picture element regions, the transmittance also differs between the picture element regions. In particular, the difference in the alignment state of the liquid crystal layer is remarkable between the pixel area where the white display state is changed to the halftone display state and the pixel area where the black display state is changed to the halftone display state. The difference in the rate is easily visible as an afterimage phenomenon. Because, in the white display state,
The oblique electric field generated at the edge of the opening exerts a relatively strong alignment regulating force, so the alignment of the liquid crystal layer is stable,
Therefore, while the alignment of the liquid crystal layer is stable even in the halftone display state thereafter, when the black display state is changed to the halftone display state, the alignment due to the oblique electric field generated at the edge portion of the opening is performed. This is because the regulation force is relatively weak and the alignment of the liquid crystal layer is likely to collapse.

In the liquid crystal display device according to the present invention, in each of the plurality of picture element regions, among the plurality of openings of the picture element electrode, the position is between two unit solid parts which are adjacent to and adjacent to the bus line. Since at least one of the openings to be formed is configured to overlap the bus line (strictly speaking, a part of the bus line), the edge of the bus line near the opening overlapping the bus line is The unit is covered by the solid part.

Therefore, in the vicinity of the opening overlapping the bus line, the influence of the oblique electric field generated near the edge of the bus line is electrically shielded by the unit solid portion of the pixel electrode. The liquid crystal molecules of the liquid crystal layer are not subjected to the alignment regulating force by the oblique electric field generated near the edge of the bus line, but are aligned only by the oblique electric field generated at the edge of the opening. Therefore, in the liquid crystal display device according to the present invention, the orientation of the liquid crystal domain formed in the opening overlapping the bus line and the unit solid portion adjacent to the opening is not disturbed, and as a result, the response speed is lowered (response characteristics are reduced). Deterioration) and afterimage phenomenon are suppressed.

From the viewpoint of suppressing the alignment disorder due to the oblique electric field generated near the edge of the bus line, the ratio of the openings overlapping the bus line is increased, that is, the bus is formed in the unit solid part of the pixel electrode. Although it is preferable to cover a large part of the edge of the line, when the bus line is formed of a light-shielding material, a decrease in the aperture ratio due to increasing this ratio may be a problem. The ratio of the openings overlapping the bus lines may be set according to the application of the liquid crystal display device in consideration of the desired response characteristic and the opening ratio.

A configuration in which an opening located between two adjacent solid units of the unit and overlapping the bus line includes at least an opening adjacent to the gate bus line (in the two adjacent units adjacent to the bus line). Among the openings located between the real parts, at least the opening close to the gate bus line overlaps with the bus line), it is possible to effectively suppress the decrease in response speed and the occurrence of the afterimage phenomenon. You can This is because a voltage larger than that applied to the source bus line is generally applied to the gate bus line, so that the oblique electric field generated near the edge of the gate bus line is obliquely generated near the edge of the source bus line. This is because the liquid crystal molecules have a larger effect than the electric field.

Further, not only the opening located between the two adjacent unit solid parts, but also the other opening close to the bus line may be overlapped with the bus line. For example, among the plurality of openings of the pixel electrode, all of the openings close to the gate bus line may be configured to overlap the bus line.

Of course, it is also possible to adopt a structure in which the opening located between two adjacent unit solid parts and overlapping the bus line includes an opening close to the source bus line.

The oblique electric field generated near the edge of the bus line causes not only the decrease in response speed and the afterimage phenomenon described above but also the decrease in contrast ratio, but the bus line is shielded from light. When it is formed of a material having a property, a decrease in contrast ratio is suppressed as described below.

As described above, an oblique electric field is generated in the vicinity of the edge of the bus line. This oblique electric field is generated regardless of the voltage applied to the liquid crystal layer between the pixel electrode and the counter electrode. To be done. Therefore, in a liquid crystal display device that displays a normally black mode, when no voltage is applied,
When the liquid crystal molecules near the edge of the bus line are tilted by the alignment control force due to this oblique electric field, light leakage occurs,
The contrast ratio may decrease. In particular, since a relatively large voltage for turning off the switching element is applied to the gate bus line most of the time, this light leakage is remarkable near the edge of the gate bus line.

In the liquid crystal display device according to the present invention, the edge of the bus line in the vicinity of the opening overlapping the bus line is covered by the unit solid part of the pixel electrode, and an oblique line is generated near the edge of the bus line. Since the influence of the electric field is electrically shielded, the liquid crystal molecules in the liquid crystal layer do not tilt due to the alignment regulating force due to this oblique electric field. Although the liquid crystal molecules of the liquid crystal layer in the opening overlapping with the bus line may tilt due to the electric field generated between the bus line and the counter electrode, if the bus line is formed of a light shielding material, the bus line The opening overlapping with is shielded from light. Therefore, in the liquid crystal display device according to the present invention, when the bus line is formed of the light-shielding material, the occurrence of light leakage is suppressed, and the reduction of the contrast ratio is suppressed.

Further, when the bus line is made of a material having a light-shielding property, the occurrence of unevenness (local variation in contrast ratio) in the display surface is suppressed and the display quality is improved, as will be described below. improves.

Due to the oblique electric field generated near the edge of the bus line, a residual potential is apt to be generated in the opening where the insulating material is exposed, and liquid crystal molecules in the opening near the bus line have a residual potential. If it is tilted under the influence of, it will cause light leakage. The degree to which the residual potential remains depends on the surface state of the insulating material, but the surface state of the insulating material varies during printing of the alignment film or injection of the liquid crystal material. Therefore, in the liquid crystal display device, the residual potential varies within the display surface. When the residual potential varies within the display surface, the degree of light leakage varies within the display surface, causing local variations in the contrast ratio and causing unevenness. Especially for the gate bus line,
Since a relatively large voltage is applied as described above, the gate bus line greatly contributes to the occurrence of the unevenness.

In the liquid crystal display device according to the present invention, when the bus line is made of a light-shielding material, the opening overlapping with the bus line is shielded by the bus line, so that the above-mentioned unevenness occurs. It is suppressed and the display quality is improved.

At least a part of the plurality of openings has substantially the same shape and the same size, and forms at least one unit cell arranged so as to have rotational symmetry. By doing so, since a plurality of liquid crystal domains can be arranged with high symmetry with the unit lattice as a unit, the viewing angle dependency of display quality can be improved. Furthermore, by dividing the entire pixel region into unit lattices, it is possible to stabilize the alignment of the liquid crystal layer over the entire pixel region. For example, the openings are arranged so that the centers of the openings form a square lattice. When one picture element region is divided by opaque components such as auxiliary capacitance wiring, a unit grid may be arranged for each region that contributes to display.

Liquid crystal formed in the openings by making each of at least some of the openings (typically, the openings forming the unit lattice) have a shape having rotational symmetry. The stability of the radial tilted orientation of the domains can be increased. For example, the shape of each opening (the shape when viewed from the substrate normal direction) is a circle or a regular polygon (for example, a square). It should be noted that, depending on the shape (aspect ratio) of the picture element, etc., it may be a shape having no rotational symmetry (eg, an ellipse). In addition, the stability of radial tilt alignment of the liquid crystal domains formed in the solid portion is obtained by the region of the solid portion substantially surrounded by the opening, that is, the shape of the unit solid portion has rotational symmetry. Can be increased. For example, when arranging the openings in a square lattice,
The shape of the opening may be substantially star-shaped or cross-shaped, and the shape of the solid portion may be substantially circular or square. Of course, both the opening and the solid portion substantially surrounded by the opening may have a substantially square shape.

In order to stabilize the radial tilt alignment of the liquid crystal domain formed in the opening of the electrode, the liquid crystal domain formed in the opening is preferably substantially circular. Conversely speaking, the shape of the opening may be designed so that the liquid crystal domain formed in the opening has a substantially circular shape.

Of course, in order to stabilize the radial tilt alignment of the liquid crystal domain formed in the solid part of the electrode, the solid part region substantially surrounded by the opening is preferably substantially circular. . A certain liquid crystal domain formed in a solid portion formed of a continuous conductive film is formed corresponding to a solid portion region (unit solid portion) substantially surrounded by a plurality of openings. To be done. Therefore, the shape and the arrangement of the openings may be determined so that the shape of the region of this solid portion (unit solid portion) is substantially circular.

In any of the above cases, it is preferable that the total area of the openings formed in the electrodes in each of the picture element regions is smaller than the area of the solid portion. The larger the area of the solid part, the larger the area of the liquid crystal layer that is directly affected by the electric field generated by the electrode (defined in the plane when viewed from the substrate normal direction),
Optical characteristics (for example, transmittance) of the liquid crystal layer with respect to voltage are improved.

Whether to adopt a structure in which the opening is substantially circular,
Whether to adopt a configuration in which the unit solid portion has a substantially circular shape is preferably determined depending on which configuration can increase the area of the solid portion. Which configuration is preferable is appropriately selected depending on the pitch of the picture element. Typically, when the pitch exceeds about 25 μm, it is preferable to form the openings so that the solid portion has a substantially circular shape, and the solid portion has a diameter of about 2 μm.
When the thickness is 5 μm or less, it is preferable that the opening has a substantially circular shape.

Since the alignment regulating force due to the oblique electric field generated at the edge portion of the opening formed in the electrode acts only when voltage is applied, no voltage is applied or a relatively low voltage is applied. For example, when an external force is applied to the liquid crystal panel, the radial tilt alignment of the liquid crystal domain may not be maintained. In order to solve this problem, a liquid crystal display device according to an embodiment of the present invention has a side surface having an alignment regulating force in the same direction as the alignment regulating direction by the above-mentioned oblique electric field for the liquid crystal molecules of the liquid crystal layer. The convex portion is provided inside the opening of the electrode. The cross-sectional shape of the convex portion in the in-plane direction of the substrate is the same as the shape of the opening portion, and like the shape of the opening portion described above, it is preferable to have rotational symmetry.

In the liquid crystal display device according to the present invention, a stable radial tilt alignment is realized by providing an opening in the pixel electrode and setting the opening of the pixel electrode and the edge of the bus line in a predetermined positional relationship. can do. That is, in the known manufacturing method, when the conductive film is patterned into the shape of the pixel electrode, the photomask is modified so that the openings having the desired shape are formed in the desired arrangement, and the bus lines are patterned. At this time, the liquid crystal display device according to the present invention can be manufactured only by modifying the photomask so that the bus line is formed in a desired shape.

In another liquid crystal display device according to the present invention, at least one edge of the gate bus line and the source bus line is covered with the solid portion of the pixel electrode. Therefore, in the vicinity of the bus line whose edge is covered with the solid portion of the pixel electrode, the influence of the oblique electric field generated near the edge of the bus line is electrically shielded, and the alignment due to this oblique electric field is performed. The liquid crystal molecules in the liquid crystal layer do not tilt due to the regulation force. Therefore, the occurrence of light leakage is suppressed, and the decrease in contrast ratio is suppressed. In addition, the area near the edge covered by the solid part of the pixel electrode is
Since it is covered with the conductive film (solid portion) of the picture element electrode, residual potential hardly occurs and unevenness is suppressed. As described above, in the other liquid crystal display device according to the present invention, the occurrence of light leakage due to the oblique electric field generated in the vicinity of the bus line is suppressed, the decrease in the contrast ratio is suppressed, and the residual liquid in the vicinity of the bus line is suppressed. Since the occurrence of unevenness due to the potential is suppressed, high-quality display is realized.

Since the oblique electric field generated near the edge of the gate bus line has a larger effect on the liquid crystal molecules than the oblique electric field generated near the edge of the source bus line, at least the edge of the gate bus line is drawn. It is preferable to cover with the solid part of the elementary electrode. Further, from the viewpoint of more reliably suppressing the influence of the oblique electric field generated near the edge of the bus line, it is preferable to cover both edges of the gate bus line and the source bus line with the solid portion of the pixel electrode.

[0059]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, the electrode structure of the liquid crystal display device of the present invention and its action will be described. An embodiment of the present invention will be described below for an active matrix type liquid crystal display device using a thin film transistor (TFT). Also,
Hereinafter, the embodiment of the present invention will be described by taking a transmissive liquid crystal display device as an example, but the present invention is not limited to this, and can be applied to a reflective liquid crystal display device and a transflective liquid crystal display device.

In the present specification, the area of the liquid crystal display device corresponding to the "picture element" which is the minimum unit of display is referred to as "picture element area". In a color liquid crystal display device,
The “picture element” of R, G, B corresponds to one “pixel”. In an active matrix type liquid crystal display device, a pixel electrode and a counter electrode facing the pixel electrode define a pixel region. Note that, strictly speaking, in the configuration in which the black matrix is provided, the region corresponding to the opening of the black matrix corresponds to the pixel region in the region to which the voltage is applied according to the state to be displayed. .

Referring to FIGS. 1 (a) and 1 (b),
The structure of one picture element region of the liquid crystal display device 100 according to the embodiment of the present invention will be described. In the following, the color filter and the black matrix are omitted for simplicity of description.
Further, in the following drawings, components having substantially the same functions as those of the liquid crystal display device 100 are designated by the same reference numerals, and the description thereof will be omitted. FIG. 1A is a top view seen from the direction normal to the substrate, and FIG. 1B is FIG. 1A.
It corresponds to a cross-sectional view taken along the line 1B-1B ′ in FIG. Figure 1
(B) shows a state in which no voltage is applied to the liquid crystal layer.

The liquid crystal display device 100 includes an active matrix substrate (hereinafter referred to as "TFT substrate") 100a,
Counter substrate (also referred to as "color filter substrate") 100b
And a liquid crystal layer 30 provided between the TFT substrate 100a and the counter substrate 100b. The liquid crystal molecules 30a of the liquid crystal layer 30 have a negative dielectric anisotropy, and the TFT substrate 1
00a and the vertical alignment film (not shown) as a vertical alignment layer provided on the surface of the counter substrate 100b on the liquid crystal layer 30 side, when no voltage is applied to the liquid crystal layer 30, it is shown in FIG. As described above, the alignment is performed perpendicularly to the surface of the vertical alignment film. At this time, the liquid crystal layer 30 is said to be in a vertically aligned state. However, the liquid crystal molecules 30a of the liquid crystal layer 30 in the vertical alignment state may be slightly inclined from the normal line of the surface of the vertical alignment film (the surface of the substrate) depending on the type of the vertical alignment film and the type of liquid crystal material. Generally, the liquid crystal molecular axis (also referred to as “axis orientation”) is about 85 ° with respect to the surface of the vertical alignment film.
The state of being oriented at the above angles is called the vertical orientation state.

The TFT substrate 100a of the liquid crystal display device 100
Has a transparent substrate (eg glass substrate) 11 and a pixel electrode 14 formed on the surface thereof. Counter substrate 100
b has a transparent substrate (for example, a glass substrate) 21 and a counter electrode 22 formed on the surface thereof. The alignment state of the liquid crystal layer 30 for each pixel region changes according to the voltage applied to the pixel electrode 14 and the counter electrode 22 which are arranged so as to face each other with the liquid crystal layer 30 interposed therebetween. Display is performed by utilizing a phenomenon in which the polarization state and amount of light passing through the liquid crystal layer 30 changes as the alignment state of the liquid crystal layer 30 changes.

The pixel electrode 14 of the liquid crystal display device 100
Has a plurality of openings 14a and a solid portion 14b. The opening 14a indicates a portion of the pixel electrode 14 formed of a conductive film (for example, an ITO film) from which the conductive film is removed, and the solid portion 14b indicates a portion where the conductive film exists (other than the opening 14a). Part)). A plurality of openings 14a are formed for each picture element electrode, but the solid part 14b is basically formed of a single continuous conductive film.

The plurality of openings 14a are arranged so that the centers thereof form a square lattice, and the four openings 14a whose centers are located on the four lattice points forming one unit lattice are substantially formed. A solid portion (referred to as a “unit solid portion”) 14b ′ surrounded by a circle has a substantially circular shape. Each opening 14a is a substantially star shape having four quarter-arc sides (edges) and having a four-fold rotation axis at the center thereof. Here, in order to stabilize the orientation over the entire pixel region, a unit lattice is formed up to the end of the pixel electrode 14. That is, as shown in the figure, the end portion of the picture element electrode 14 has about a half (a region corresponding to a side) and about a quarter (corner) of the opening 14a located at the center of the picture element electrode 14. Is patterned in a shape corresponding to a region (corresponding to the area).
4a is arranged.

Opening 14a located in the center of the picture element area
Have substantially the same shape and the same size. The unit solid portions 14b ′ located in the unit lattice formed by the openings 14a are substantially circular, and have substantially the same shape and the same size. Unit solid parts 14 adjacent to each other
b'is connected to each other and constitutes a solid portion 14b which functions as a substantially single conductive film.

The picture element electrode 14 having the structure as described above.
When a voltage is applied between the counter electrode 22 and the counter electrode 22, the opening 14
The oblique electric field generated at the edge portion of a forms a plurality of liquid crystal domains each having a radial tilt alignment. One liquid crystal domain is formed in each of the regions corresponding to the openings 14a and the regions corresponding to the unit solid portions 14b 'in the unit lattice.

Although the square picture element electrode 14 is illustrated here, the shape of the picture element electrode 14 is not limited to this.
Since the general shape of the pixel electrode 14 is approximate to a rectangle (including a square and a rectangle), the openings 14a can be regularly arranged in a square lattice. Even if the pixel electrode 14 has a shape other than a rectangle, the openings 14a are regularly formed (for example, in a square lattice shape as illustrated) so that liquid crystal domains are formed in all areas within the pixel area. If arranged, the effect of the present invention can be obtained.

A mechanism of forming a liquid crystal domain by the above-mentioned oblique electric field will be described with reference to FIGS. 2 (a) and 2 (b). 2A and 2B show a state in which a voltage is applied to the liquid crystal layer 30 shown in FIG. 1B, and FIG. 2A shows the voltage applied to the liquid crystal layer 30. Accordingly, the state in which the alignment of the liquid crystal molecules 30a starts to change (ON initial state) is schematically shown in FIG.
Shows schematically a state in which the alignment of the liquid crystal molecules 30a changed according to the applied voltage reaches a steady state. A curve EQ in FIGS. 2A and 2B shows an equipotential line EQ.

When the pixel electrode 14 and the counter electrode 22 have the same potential (in the state where no voltage is applied to the liquid crystal layer 30), as shown in FIG. The molecules 30a are oriented perpendicular to the surfaces of both substrates 11 and 21.

When a voltage is applied to the liquid crystal layer 30, FIG.
A potential gradient represented by the equipotential line EQ (which is orthogonal to the line of electric force) shown in (a) is formed. This equipotential line EQ is
In the liquid crystal layer 30 located between the solid portion 14b of the pixel electrode 14 and the counter electrode 22, it is parallel to the surfaces of the solid portion 14b and the counter electrode 22, and the opening 14a of the pixel electrode 14 is formed. Falls in a region corresponding to the edge portion of the opening 14a (the opening 14a including the boundary (extension) of the opening 14a).
An oblique electric field represented by a tilted equipotential line EQ is formed in the liquid crystal layer 30 on the inner periphery (EG) of EG.

The liquid crystal molecule 30a having a negative dielectric anisotropy is subjected to a torque that tends to orient the axial direction of the liquid crystal molecule 30a parallel to the equipotential line EQ (perpendicular to the electric force line). To do. Therefore, the liquid crystal molecules 30 on the edge portion EG
As indicated by an arrow in FIG. 2A, a is inclined (rotated) in the clockwise direction at the right edge portion EG in the figure and in the counterclockwise direction at the left edge portion EG in the figure. ,
It is oriented parallel to the equipotential line EQ.

Here, referring to FIG. 3, the liquid crystal molecules 3
The change in the orientation of 0a will be described in detail.

When an electric field is generated in the liquid crystal layer 30, a torque acts to orient the liquid crystal molecules 30a having a negative dielectric anisotropy so that their axial directions are parallel to the equipotential line EQ. To do. As shown in FIG. 3A, the liquid crystal molecules 30
When an electric field represented by an equipotential line EQ perpendicular to the axis direction of a is generated, a torque that tilts clockwise or counterclockwise acts on the liquid crystal molecules 30a with equal probability. Therefore, in the liquid crystal layer 30 between the parallel plate type electrodes facing each other, liquid crystal molecules 30a that receive a torque in the clockwise direction and liquid crystal molecules 30a that receive a torque in the counterclockwise direction are mixed. As a result, the change to the alignment state depending on the voltage applied to the liquid crystal layer 30 may not occur smoothly.

As shown in FIG. 2A, at the edge portion EG of the opening 14a of the liquid crystal display device 100 according to the present invention, the equipotential line EQ inclined with respect to the axial direction of the liquid crystal molecule 30a is represented. When an electric field (oblique electric field) occurs,
As shown in (b), the liquid crystal molecules 30a have equipotential lines E
Inclination is performed in a direction (counterclockwise in the illustrated example) in which the amount of inclination to be parallel to Q is small. Further, the liquid crystal molecule 30a located in a region where an electric field represented by an equipotential line EQ perpendicular to the axial direction of the liquid crystal molecule 30a is generated is shown in FIG.
, The liquid crystal molecules 30a located on the tilted equipotential line EQ are aligned (continuously aligned) with the liquid crystal molecules 30a located on the tilted equipotential line EQ.
It is inclined in the same direction as a. As shown in FIG. 3 (d),
When an electric field that forms a concavo-convex shape in which the equipotential lines EQ are continuous is applied, a flat equipotential line is formed so as to be aligned with the alignment direction regulated by the liquid crystal molecules 30a located on each inclined equipotential line EQ. Liquid crystal molecule 3 located on the line EQ
0a is oriented. In addition, "it is located on the equipotential line EQ".
Means “positioned within the electric field represented by the equipotential line EQ”.

As described above, when the orientation changes starting from the liquid crystal molecules 30a located on the tilted equipotential line EQ and reaches the steady state, the orientation state schematically shown in FIG. 2B is obtained. . Since the liquid crystal molecules 30a located near the center of the opening 14a are almost equally affected by the alignment of the liquid crystal molecules 30a of the edge portions EG on both sides of the opening 14a facing each other, the liquid crystal molecules 30a are perpendicular to the equipotential line EQ. Liquid crystal molecules 3 in an area that maintains the alignment state and is away from the center of the opening 14a
0a is the liquid crystal molecule 30 of the edge portion EG which is closer to each other.
The center S of the opening 14a is inclined due to the influence of the orientation of a.
Form a tilted orientation that is symmetric with respect to A. This alignment state is in the direction perpendicular to the display surface of the liquid crystal display device 100 (the substrate 1
When viewed from the direction perpendicular to the surfaces of 1 and 21), the axial orientation of the liquid crystal molecules 30a is in a state of being radially aligned with respect to the center of the opening 14a (not shown). Therefore, in the present specification, such an alignment state is referred to as “radial tilt alignment”.
I will call it. A region of the liquid crystal layer having a radial tilt alignment with respect to one center is called a liquid crystal domain.

In the region corresponding to the unit solid portion 14b 'substantially surrounded by the opening 14a, a liquid crystal domain in which the liquid crystal molecules 30a have a radial tilt alignment is formed. Liquid crystal molecules 3 in a region corresponding to the unit solid part 14b '
0a is the liquid crystal molecule 30a of the edge portion EG of the opening 14a.
Is affected by the orientation of the center SA of the unit solid part 14b '
A radial tilt orientation symmetrical with respect to (corresponding to the center of the unit lattice formed by the opening 14a) is adopted.

The radial slanted alignment in the liquid crystal domain formed in the unit solid portion 14b 'and the radial slanted alignment formed in the opening 14a are continuous, and both are in the opening 14a.
The liquid crystal molecules 30a in the edge portion EG of a are aligned so as to be aligned with the liquid crystal molecules 30a. The liquid crystal molecules 30a in the liquid crystal domain formed in the opening 14a are aligned in a cone shape with the upper side (substrate 100b side) being open, and the liquid crystal molecules 30a in the liquid crystal domain formed in the unit solid portion 14b ′ are lower. Side (substrate 10
(0a side) is oriented in an open cone shape. As described above, since the radial tilt alignments formed in the liquid crystal domain formed in the opening 14a and the liquid crystal domain formed in the unit solid portion 14b ′ are continuous with each other, the disclination line ( Alignment defects) are not formed, so that the display quality does not deteriorate due to the occurrence of disclination lines.

In order to improve the viewing angle dependence of the display quality of the liquid crystal display device in all directions, the existence probability of the liquid crystal molecules oriented along all the azimuth directions in each pixel region is rotated. It is preferable to have symmetry, and more preferable to have axial symmetry. That is, it is preferable that the liquid crystal domains formed over the entire pixel region be arranged so as to have rotational symmetry and further axial symmetry. However, it is not always necessary to have rotational symmetry over the entire pixel region, and liquid crystal domains arranged so as to have rotational symmetry (or axial symmetry) (for example, a plurality of liquid crystal domains arranged in a square lattice shape). The liquid crystal layer in the pixel region may be formed as an aggregate of liquid crystal domains). Therefore, the plurality of openings 14 formed in the pixel area
The arrangement of a does not necessarily need to have rotational symmetry over the entire pixel region, and openings arranged so as to have rotational symmetry (or axial symmetry) (for example, a plurality of square lattice-shaped arrangements). It can be represented as an aggregate of (opening portions).
Of course, the arrangement of the unit solid portion 14b 'substantially surrounded by the plurality of openings 14a is also the same. Further, since it is preferable that the shape of each liquid crystal domain also has rotational symmetry and further axial symmetry, the shape of each opening 14a and unit solid portion 14b 'also has rotational symmetry and further axial symmetry. It is preferable.

The liquid crystal layer 3 near the center of the opening 14a.
In some cases, a sufficient voltage is not applied to 0, and the liquid crystal layer 30 near the center of the opening 14a may not contribute to display. That is, even if the radial tilt alignment of the liquid crystal layer 30 near the center of the opening 14a is disturbed to some extent (for example, the central axis deviates from the center of the opening 14a), the display quality may not deteriorate. Therefore, it is sufficient that at least the liquid crystal domains formed corresponding to the unit solid portions 14b 'are arranged to have rotational symmetry and further axial symmetry.

As described with reference to FIGS. 2A and 2B, the picture element electrode 14 of the liquid crystal display device 100 according to the present invention has a plurality of openings 14a, and the picture element electrode 14 has a plurality of openings 14a. An equipotential line E having an inclined region in the liquid crystal layer 30.
An electric field represented by Q is formed. The liquid crystal molecules 30a having a negative dielectric anisotropy in the liquid crystal layer 30 in the vertical alignment state when no voltage is applied change the alignment direction by using the alignment change of the liquid crystal molecules 30a located on the inclined equipotential line EQ as a trigger. Then, a liquid crystal domain having a stable radial tilt alignment is formed in the opening 14a and the solid portion 14b. Display is performed by changing the orientation of the liquid crystal molecules of the liquid crystal domain according to the voltage applied to the liquid crystal layer.

The shape of the opening 14a of the pixel electrode 14 of the liquid crystal display device 100 of this embodiment (the shape as viewed from the direction normal to the substrate) and its arrangement will be described.

The display characteristics of the liquid crystal display device show azimuth angle dependence due to the alignment state (optical anisotropy) of the liquid crystal molecules. In order to reduce the azimuth angle dependence of display characteristics, it is preferable that the liquid crystal molecules are aligned with equal probability for all azimuth angles. Further, it is more preferable that the liquid crystal molecules in each pixel region are aligned with the same probability for all azimuth angles. Therefore, the opening 14a preferably has a shape that forms a liquid crystal domain so that the liquid crystal molecules 30a in each picture element region are aligned with equal probability for all azimuth angles. . Specifically, the shape of the opening 14a preferably has a rotational symmetry (preferably a symmetry of two or more rotation axes) about each center (normal direction) as a symmetry axis. The openings 14a are preferably arranged so as to have rotational symmetry. Further, the shape of the unit solid portion 14b 'substantially surrounded by these openings also preferably has rotational symmetry, and the unit solid portion 14b' may also be arranged so as to have rotational symmetry. preferable.

However, the opening portion 14a and the unit solid portion 14b '
Need not necessarily be arranged so as to have rotational symmetry over the entire pixel region, and as shown in FIG. 1A, for example, a square lattice (symmetry with a four-fold rotation axis) is the minimum unit. If the pixel area is formed by the combination thereof, the liquid crystal molecules can be aligned over the entire pixel area with substantially the same probability with respect to all azimuth angles.

As shown in FIG. 1A, a substantially star-shaped opening 14a having a rotational symmetry and a substantially circular unit solid portion 14b.
The alignment state of the liquid crystal molecules 30a in the case where are arranged in a square lattice will be described with reference to FIGS. 4 (a) to 4 (c).

4 (a) to 4 (c) each schematically show the alignment state of the liquid crystal molecules 30a viewed from the direction of the normal to the substrate. 4 (b) and 4 (c), etc., showing the alignment state of the liquid crystal molecules 30a viewed from the substrate normal direction,
The end of the liquid crystal molecule 30a drawn in an elliptical shape with a black tip is closer to the substrate side where the pixel electrode 14 having the opening 14a is provided than the other end. It is shown that the molecule 30a is inclined. The same applies to the following drawings. Here, one unit cell (four openings 14a) in the picture element region shown in FIG.
(Formed by) is described. 4 (a)-
Sections along the diagonal line in FIG. 4C correspond to FIGS. 1B, 2A, and 2B, respectively, and will be described with reference to these drawings.

When the pixel electrode 14 and the counter electrode 22 have the same potential, that is, when no voltage is applied to the liquid crystal layer 30, the TFT substrate 100a and the counter substrate 1
Liquid crystal molecules 30 whose alignment direction is regulated by a vertical alignment layer (not shown) provided on the surface of the liquid crystal layer 30 on the liquid crystal layer 30 side.
As shown in FIG. 4A, a has a vertical alignment state.

When an electric field is applied to the liquid crystal layer 30 and an electric field represented by the equipotential line EQ shown in FIG. 2A is generated, the liquid crystal molecules 30a having negative dielectric anisotropy have an axial orientation. Is generated in parallel with the equipotential line EQ. Figure 3
As described with reference to (a) and (b), the liquid crystal molecules 30a under the electric field represented by the equipotential line EQ perpendicular to the molecular axis of the liquid crystal molecules 30a are inclined (rotated). ) Is not uniquely determined (Fig. 3
(A)), while the change in orientation (tilt or rotation) does not easily occur, the liquid crystal molecules 30a placed under the equipotential line EQ tilted with respect to the molecular axis of the liquid crystal molecules 30a tilt (rotate). ) Since the direction is uniquely determined, a change in orientation easily occurs. Therefore, as shown in FIG. 4B, the liquid crystal molecules 30a start to tilt from the edge of the opening 14a in which the molecular axis of the liquid crystal molecules 30a tilts with respect to the equipotential line EQ. Then, as described with reference to FIG. 3C, the tilted liquid crystal molecules 30a at the edge of the opening 14a.
The surrounding liquid crystal molecules 30a are also tilted so as to be consistent with the orientation of the liquid crystal molecules 30a
The axis orientation of is stable (radial tilt orientation).

As described above, when the opening 14a has a shape having rotational symmetry, the liquid crystal molecules 30a in the picture element region are
When a voltage is applied, the opening 14a moves from the edge of the opening 14a.
Since the liquid crystal molecules 30a are inclined toward the center of a, the liquid crystal molecules 30a in the vicinity of the center of the opening 14a where the alignment control force of the liquid crystal molecules 30a from the edge portion balances with each other and maintain the state of being aligned vertically to the substrate surface. And the liquid crystal molecules around it 3
It is possible to obtain a state in which the liquid crystal molecules 30a are continuously inclined radially with 0a being the liquid crystal molecule 30a near the center of the opening 14a.

Also, a substantially circular unit solid portion 14 surrounded by four substantially star-shaped openings 14a arranged in a square lattice pattern.
The liquid crystal molecules 30a in the region corresponding to b'also have openings 14a.
Liquid crystal molecules 3 tilted by an oblique electric field generated at the edge of
It is tilted to match the orientation of 0a. Unit solid part 14 in which the alignment regulating force of the liquid crystal molecules 30a from the edge part is balanced
The liquid crystal molecules 30a near the center of b'maintain the state of being aligned perpendicularly to the substrate surface, and the liquid crystal molecules 30a around the liquid crystal molecules 30a around the center of the unit solid portion 14b 'are liquid crystal radially. A state in which the molecules 30a are continuously inclined is obtained.

In this way, when the liquid crystal domains in which the liquid crystal molecules 30a have a radial tilt alignment are arranged in a square lattice pattern over the entire pixel region, the liquid crystal molecules 3 in the respective axial directions are formed.
Since the existence probability of 0a has rotational symmetry, it is possible to realize a high-quality display without roughness in any viewing angle direction. In order to reduce the viewing angle dependence of the liquid crystal domain having the radial tilt alignment, it is preferable that the liquid crystal domain has high rotational symmetry (a rotation axis of 2 times or more is preferable, and a rotation axis of 4 times or more is more preferable). Further, in order to reduce the viewing angle dependency of the entire pixel region, the plurality of liquid crystal domains formed in the pixel region have high rotational symmetry (a rotation axis of 2 times or more is preferable, and a rotation axis of 4 times or more is further preferable. It is preferable to form an array (for example, a square lattice) represented by a combination of units (for example, a unit lattice) having (preferably).

The radial tilted alignment of the liquid crystal molecules 30a is counterclockwise as shown in FIGS. 5 (b) and 5 (c) rather than the simple radial tilted alignment shown in FIG. 5 (a). A clockwise spiral radial tilt orientation is more stable. In this spiral alignment, the alignment direction of the liquid crystal molecules 30a does not change spirally along the thickness direction of the liquid crystal layer 30 unlike the normal twist alignment, but the alignment direction of the liquid crystal molecules 30a is observed in a minute region. Thus, there is almost no change along the thickness direction of the liquid crystal layer 30. That is, the liquid crystal layer 30
The cross-section at any position in the thickness direction (cross-section in the plane parallel to the layer surface) is in the same alignment state as in FIG. 5B or 5C, and is along the thickness direction of the liquid crystal layer 30. Almost no twist deformation occurs. However, in the liquid crystal domain as a whole, some twist deformation occurs.

When a material in which a chiral agent is added to a nematic liquid crystal material having a negative dielectric anisotropy is used, the liquid crystal molecules 30a are centered around the opening 14a and the unit solid portion 14b 'when a voltage is applied. Shown in (b) and (c),
Take a left-handed or right-handed spiral radial tilted orientation.
Whether it is clockwise or counterclockwise depends on the type of chiral agent used. Therefore, when the voltage is applied, the liquid crystal layer 3 in the opening 14a is
By making 0 a spiral radial tilt orientation, the direction in which the liquid crystal molecules 30a tilted radially are wound around the liquid crystal molecules 30a standing perpendicular to the substrate surface is made constant in all liquid crystal domains. As a result, it is possible to display a uniform display without roughness. Furthermore, since the direction of winding around the liquid crystal molecules 30a standing perpendicular to the substrate surface is fixed, the response speed when a voltage is applied to the liquid crystal layer 30 is also improved.

When the chiral agent is added, the orientation of the liquid crystal molecules 30a changes spirally along the thickness direction of the liquid crystal layer 30 like the usual twist orientation. In the alignment state in which the alignment of the liquid crystal molecules 30a does not change spirally along the thickness direction of the liquid crystal layer 30, the liquid crystal molecules 30 aligned vertically or parallel to the polarization axis of the polarizing plate.
Since a does not give a phase difference to the incident light, the incident light passing through the region in such an alignment state does not contribute to the transmittance. On the other hand, in the orientation state in which the orientation of the liquid crystal molecules 30a changes spirally along the thickness direction of the liquid crystal layer 30, the liquid crystal molecules 30a also oriented in the direction perpendicular to or parallel to the polarization axis of the polarizing plate. It is also possible to give a phase difference to incident light and utilize the optical rotatory power of the light. Therefore, the incident light passing through the region in such an alignment state also contributes to the transmittance, so that a liquid crystal display device capable of bright display can be obtained.

FIG. 1A shows an example in which the openings 14a have a substantially star shape and the unit solid parts 14b 'have a substantially circular shape, and these are arranged in a square lattice. The shapes of the portion 14a and the unit solid portion 14b ′ and their arrangement are
It is not limited to the above example.

FIGS. 6 (a) and 6 (b) are top views of the pixel electrodes 14A and 14B having the openings 14a and the unit solid portions 14b 'having different shapes, respectively.

The openings 14a and the unit solid portions 14b of the picture element electrodes 14A and 14B shown in FIGS. 6A and 6B respectively correspond to the openings 14a of the picture element electrodes shown in FIG. 1A. And the unit solid portion 14b 'has a slightly distorted shape. Openings 14 in picture element electrodes 14A and 14B
a and the unit solid part 14b 'have a double rotation axis (4
It has no axis of rotation) and is regularly arranged to form a rectangular unit cell. Each of the openings 14a has a distorted star shape, and each of the unit solid portions 14b 'has a substantially elliptical shape (distorted circle). Picture element electrode 14A
And 14B, a liquid crystal display device having high display quality and excellent viewing angle characteristics can be obtained.

Further, picture element electrodes 14C and 14D as shown in FIGS. 7A and 7B, respectively, can also be used.

The pixel electrodes 14C and 14D have a substantially cross-shaped opening 1 so that the unit solid portion 14b 'is substantially square.
4a are arranged in a square lattice. Of course, they may be distorted and arranged so as to form a rectangular unit cell. As described above, even if the unit solid portions 14b ′ of a substantially rectangular shape (a rectangular shape includes a square shape and a rectangular shape) are regularly arranged, a liquid crystal display device having high display quality and excellent viewing angle characteristics can be obtained. .

However, it is preferable that the opening 14a and / or the unit solid portion 14b 'have a circular or elliptical shape rather than a rectangular shape because the radial inclined orientation can be stabilized. It is considered that this is because the sides of the opening 14a change continuously (smoothly), and the orientation direction of the liquid crystal molecules 30a also changes continuously (smoothly).

From the viewpoint of the continuity of the alignment direction of the liquid crystal molecules 30a, the pixel electrodes 14E and 14F shown in FIGS. 8A and 8B are also conceivable. The picture element electrode 14E shown in FIG. 8A is a modified example of the picture element electrode 14 shown in FIG. 1A and has an opening 14a consisting of only four arcs. In addition, the picture element electrode 14F shown in FIG.
In the modified example of the pixel electrode 14D shown in FIG. 7B, the unit solid portion 14b 'side of the opening 14a is formed in an arc. Openings 14a of the picture element electrodes 14E and 14F
Each of the unit solid parts 14b ′ has a rotation axis of four times, and has a square lattice shape (having a rotation axis of four times).
However, as shown in FIGS. 6 (a) and 6 (b), the shape of the unit solid portion 14b ′ of the opening 14a is distorted into a shape having a double rotation axis, and a rectangular grid is formed. (2
May have a rotation axis).

In the above example, the substantially star-shaped or substantially cross-shaped opening 14a is formed, and the unit solid portion 14b 'has a substantially circular shape.
The configurations of the substantially elliptical shape, the substantially square shape (rectangular shape), and the substantially rectangular shape with rounded corners have been described. On the other hand, the relationship between the opening portion 14a and the unit solid portion 14b 'may be inverted in negative-positive. For example, FIG. 9 shows a pixel electrode 14G having a pattern in which the opening 14a and the unit solid portion 14b of the pixel electrode 14 shown in FIG. Thus, the picture element electrode 14 having the negative-positive inverted pattern
G also has a function substantially similar to that of the pixel electrode 14 shown in FIG. It should be noted that the opening 14a is formed like the pixel electrodes 14H and 14I shown in FIGS. 10A and 10B, respectively.
When both the unit solid part 14b 'and the unit solid part 14b' are substantially square, even if the negative-positive reversal is performed, the pattern may be the same as the original pattern.

As the pattern shown in FIG.
Even when the pattern shown in (a) is negative-positive inverted, one portion of the opening 14a is formed so that the unit solid portion 14b ′ having rotational symmetry is formed at the edge portion of the pixel electrode 14. It is preferred to form parts (about one-half or about one-quarter). With such a pattern, even in the edge portion of the pixel region, the effect of the oblique electric field is obtained similarly to the central portion of the pixel region, and a stable radial tilt alignment is provided over the entire pixel region. Can be realized.

Next, FIG. 9 shows a pixel electrode 14 of FIG. 1A, and a pattern in which the pattern of the opening 14a of the pixel electrode 14 and the unit solid portion 14b 'are negative-positive inverted. Taking the pixel electrode 14G as an example, which one of the negative and positive patterns should be adopted will be described.

Whichever pattern is used, the side length of the opening 14a is the same for both patterns. Therefore, there is no difference between these patterns in the function of generating the oblique electric field. However, the area ratio of the unit solid portion 14b ′ (the ratio to the total area of the pixel electrode 14) may be different between the two. That is, the area of the solid portion 14b (the portion where the conductive film actually exists) that generates the electric field used for the liquid crystal molecules of the liquid crystal layer may be different.

Since the voltage applied to the liquid crystal domain formed in the opening 14a is lower than the voltage applied to the liquid crystal domain formed in the solid portion 14b, for example, normally black mode display is performed. Then, the liquid crystal domain formed in the opening 14a becomes dark. That is, when the area ratio of the opening 14a increases, the display brightness tends to decrease. Therefore, it is preferable that the area ratio of the solid portion 14b is high.

Which of the pattern of FIG. 1 (a) and the pattern of FIG. 9 has the higher area ratio of the solid part 14b depends on the pitch (size) of the unit lattice.

FIG. 11 (a) shows a unit cell of the pattern shown in FIG. 1 (a), and FIG. 11 (b) shows a unit cell of the pattern shown in FIG. Yes.). In addition, in FIG. 11B,
The portion (branch portion extending in four directions from the circular portion) that plays a role in connecting the unit solid portions 14b ′ to each other in FIG. 9 is omitted. The length (pitch) of one side of the square unit cell is p, and the length of the gap (one side space) between the opening 14a or the unit solid portion 14b 'and the unit cell is s.

Various pixel electrodes 14 having different values of the pitch p and the space s on one side were formed, and the stability of the radial tilt alignment was examined. As a result, first, the pattern shown in FIG. 11A (hereinafter, referred to as “positive pattern”).
It has been found that the one-side space s is required to be about 2.75 μm or more in order to generate the oblique electric field required to obtain the radial tilt alignment using the pixel electrode 14 having
On the other hand, with respect to the pixel electrode 14 having the pattern shown in FIG. 11B (hereinafter, referred to as “negative pattern”), the one-side space s is set to generate the oblique electric field for obtaining the radial tilt alignment. It was found that about 2.25 μm or more is necessary. The solid part 14b when the value of the pitch p is changed with the one side space s as the lower limit value, respectively.
The area ratio of was examined. The results are shown in Table 1 and FIG. 11 (c).
Shown in.

[0111]

Table 1 Pitch p (μm) Solid area ratio (%) Positive type (a) Negative type (b) 20 41.3 52.9 25 47.8 47.2 30 52.4 43.3 35 55 .8 40.4 40 58.4 38.2 45 60.5 36.4 50 62.2 35.0 As can be seen from Table 1 and FIG. 11C, when the pitch p is about 25 μm or more, the positive type ( The area ratio of the solid portion 14b is higher in the pattern of FIG.
When the length is shorter than μm, the area ratio of the solid portion 14b becomes larger in the negative type (FIG. 11B). Therefore, from the viewpoint of display brightness and orientation stability, the pitch p is about 25 μm.
The pattern that should be adopted changes at the border. For example, when three or less unit lattices are provided in the width direction of the picture element electrode 14 having a width of 75 μm, the positive pattern shown in FIG. 11A is preferable, and when four or more unit lattices are provided. Is preferably the negative pattern shown in FIG.
Even in cases other than the illustrated pattern, the solid portion 14b
Either the positive type or the negative type may be selected so that the area ratio of is large.

The number of unit cells is obtained as follows. With respect to the width (horizontal or vertical) of the pixel electrode 14, one or more integer unit lattices are arranged,
The size of the unit grid is calculated, the solid part area ratio is calculated for each unit grid size, and the unit grid size that maximizes the solid part area ratio is selected. However, in the case of a positive pattern, the diameter of the unit solid portion 14b ′ is less than 15 μm,
In the case of a negative pattern, the diameter of the opening 14a is 15μ
If it is less than m, the alignment regulating force due to the oblique electric field decreases,
It becomes difficult to obtain a stable radial tilt alignment. The lower limit of these diameters is when the thickness of the liquid crystal layer 30 is about 3 μm, and when the thickness of the liquid crystal layer 30 is thinner than this, the diameters of the unit solid portion 14b ′ and the opening portion 14a are A unit solid portion 14b ′ necessary for obtaining a stable radial tilt alignment when the liquid crystal layer 30 is thicker than the above, even if it is smaller than the above lower limit and a stable radial tilt alignment is obtained.
The lower limit value of the diameter of the opening 14a is larger than the above lower limit value.

As will be described later, the stability of the radial tilt alignment can be enhanced by forming a convex portion inside the opening 14a. All of the above conditions
This is for the case where no convex portion is formed.

As described above, a wide-viewing-angle display can be realized by providing an electrode structure that exerts an alignment regulating force for forming a liquid crystal domain having a radial tilt alignment state in a pixel region.

However, if only the electrode structure as described above is provided, the opening 14a of the picture element electrode 14 and the TF are not formed.
The present inventors have found that the display quality may not be sufficiently improved depending on the relative positional relationship with the edge of the bus line (wiring group) provided on the T substrate 100a. In the liquid crystal display device 100 according to the present invention, the openings 14a of the picture element electrodes 14 and the edges of the bus lines have a positional relationship as described later, which realizes high-quality display. It

Here, the positional relationship between the openings 14a of the picture element electrodes 14 and the edges of the bus lines 18 in the liquid crystal display device 100 of the present embodiment will be described with reference to FIG. FIG. 12 is a top view schematically showing a pixel region of the liquid crystal display device 100 of this embodiment. In the following drawings, the TFT provided for each pixel region on the TFT substrate 100a is omitted.

As shown in FIG. 12, the liquid crystal display device 100
The TFT substrate 100a of FIG. 1 includes a picture element electrode 14 provided for each picture element region on the liquid crystal layer 30 side, a TFT (not shown) as a switching element electrically connected to the picture element electrode 14, and this TFT. And a bus line 18 including a gate bus line (scanning wiring) 15 and a source bus line (signal wiring) 16 electrically connected to each other. In the present embodiment, the bus line 18 further has an auxiliary capacitance line 17 for forming an auxiliary capacitance.

In this embodiment, as shown in FIG.
In each of the picture element regions, a part of the openings 14a close to the bus line 18 overlaps the bus line 18. More specifically, of the openings 14a adjacent to the bus line 18, two unit solid parts 14 adjacent to and adjacent to the gate bus line 15 are provided.
The opening 14a located between b'is overlapped with the bus line 18 (gate bus line 15). That is, TFT
When viewed from the substrate 100a side, the gate bus line 15
Is configured to cover the opening 14a between the adjacent unit solid portions 14b ', and the unit solid portions 14b' sandwiching the opening 14a are the gate bus lines when viewed from the counter substrate 100b side. It is configured to cover 15 edges. Here, the gate bus line 15 is formed so as to have a branch portion that projects toward the opening 14a between the adjacent unit solid portions 14b ′.
The gate bus line 15 and the opening 14a between the adjacent unit solid portions 14b 'overlap each other.

In the liquid crystal display device 100, as described above, a part of the openings 14a close to the bus line 18 overlaps the bus line 18, which makes it possible to obtain a high quality image. Is displayed. The reason for this will be described with reference to FIGS. 13, 14, and 16 in comparison with the case where the opening 14 a close to the bus line 18 does not overlap the bus line 18.

FIG. 13 is a top view schematically showing a liquid crystal display device 700 in which the opening 14a close to the bus line 18 does not overlap the bus line 18. In addition, FIG.
(A) and (b) are liquid crystal molecules 3 near the opening 14 a near the gate bus line 15 of the liquid crystal display device 700.
It is a figure which shows the mode of the orientation of 0a typically,
14 (a) is a top view, and FIG. 14 (b) is 14 in FIG. 14 (a).
It is sectional drawing which followed the B-14B 'line. And in FIG.
(A) And (b) is the liquid crystal display device 10 of this embodiment.
16A and 16B are diagrams schematically showing the alignment of the liquid crystal molecules 30a near the opening 14a close to the gate bus line 15 of FIG. 0. FIG. 16A is a top view and FIG.
It is sectional drawing which followed the 16B-16B 'line in (a).

When driving the liquid crystal display device, the TFT substrate 1
A predetermined signal (voltage) for driving the liquid crystal display device is applied to the bus line 18 provided on 00a, so that an electric field is generated between the bus line 18 and the counter electrode 22. Therefore, an oblique electric field is generated in the vicinity of the edge of the bus line 18, but the alignment restriction force due to this oblique electric field does not match the alignment restriction force due to the oblique electric field generated at the edge portion of the opening 14a. Therefore, bus line 1
When the liquid crystal domain formed in the opening 14a near 8 is subjected to the alignment regulating force due to the oblique electric field near the edge of the bus line 18, the alignment is disturbed and the state becomes a distorted radial tilt alignment state.

For example, as shown in FIG. 13, in the liquid crystal display device 700 in which the opening 14a close to the bus line 18 does not overlap the bus line 18, the liquid crystal near the opening 14a close to the gate bus line 15 is formed. Molecule 30a
When the voltage is applied, as shown in FIG. 14B, the liquid crystal molecules 30a at the edge of the opening 14a are focused on.
Is tilted counterclockwise by the oblique electric field formed at the edge of the opening 14a, whereas the liquid crystal molecules 30a near the edge of the gate bus line 15 are near the edge of the gate bus line 15. It is tilted clockwise (clockwise) by the oblique electric field generated in. for that reason,
As shown in FIG. 14A, the liquid crystal layer 30 in the opening 14a forms a liquid crystal domain in a distorted radial tilt alignment state (here, a lazy circle).

Since the adjacent liquid crystal domains try to maintain the continuity of alignment with each other, as described above, when the alignment of the liquid crystal domains of the opening 14a close to the bus line 18 is disturbed, this disturbance of alignment is caused. Influences the alignment of the adjacent liquid crystal domain, that is, the liquid crystal domain formed in the unit solid portion 14b ', and the alignment of the liquid crystal domain of the unit solid portion 14b' is also disturbed.

A liquid crystal domain in which the orientation is disordered and has a distorted radial tilted orientation is easily broken because the orientation stability is low, and it takes a long time for the orientation to reach a steady state when a voltage is applied. Therefore, the disordered orientation as described above causes a decrease in response speed (deterioration of response characteristics).

Further, the liquid crystal layer 30 in each picture element region is in a steady state in the distorted radial tilt alignment state in which the orientation is disturbed as described above, but this state is different for each picture element region, so that an image is formed. An afterimage phenomenon in which the previous image remains may occur when a switching signal is input. This is because when the alignment state of the liquid crystal layer 30 differs between the picture element regions, the transmittance also differs between the picture element regions. In particular, the difference in the alignment state of the liquid crystal layer 30 is remarkable between the picture element region in which the white display state is changed to the halftone display state and the picture element region in which the black display state is changed to the halftone display state. The difference in transmittance is easily visible as an afterimage phenomenon. Because, in the white display state,
Since the oblique electric field generated at the edge of the opening 14a exerts a relatively strong alignment regulating force, the alignment of the liquid crystal layer 30 is stable. Therefore, the alignment of the liquid crystal layer 30 is stable even after the halftone display state. On the other hand, when the black display state is changed to the halftone display state, the alignment regulating force by the oblique electric field generated at the edge portion of the opening 14a is relatively weak, and therefore the alignment of the liquid crystal layer 30 is Because it is easy to collapse.

On the other hand, in the liquid crystal display device 100 according to the present invention, as shown in FIG. 12, some of the openings 14a close to the bus line 18 are opened, specifically, the gates. The opening 14 located close to the bus line 15 and between two adjacent unit solid portions 14b '
Since a is formed so as to overlap the bus line 18 (gate bus line 15), the edge of the bus line 18 near the opening 14a that overlaps the bus line 18 has a unit solid portion of the pixel electrode 14. It is covered by 14b '.

Therefore, in the vicinity of the opening 14a overlapping the bus line 18, the influence of the oblique electric field generated near the edge of the bus line 18 is electrically shielded by the unit solid portion 14b ′ of the pixel electrode 14. Since the liquid crystal molecules 30a of the liquid crystal layer 30 are shielded (shielded), the liquid crystal molecules 30a of the liquid crystal layer 30 are not subjected to the alignment regulating force due to the oblique electric field generated in the vicinity of the edge of the bus line 18, but only due to the oblique electric field generated at the edge of the opening 14a. Orientation is regulated.

Therefore, the liquid crystal display device 10 according to the present invention.
At 0, the opening 14a overlapping the bus line 18
And the orientation of the liquid crystal domain formed in the unit solid portion 14b ′ adjacent thereto is not disturbed, and as a result,
Reduction of response speed (deterioration of response characteristics) and occurrence of an afterimage phenomenon are suppressed, and high quality display is realized.

The oblique electric field generated near the edge of the bus line 18 causes not only the decrease in response speed and the afterimage phenomenon described above but also the decrease in contrast ratio. Is formed using a material having a light-shielding property, this reduction in contrast ratio is suppressed. The details will be described below.

As described above, an oblique electric field is generated in the vicinity of the edge of the bus line 18, and this oblique electric field is applied to the liquid crystal layer 30 between the pixel electrode 14 and the counter electrode 22. Will be generated regardless of. Therefore, in a liquid crystal display device that displays in normally black mode,
When no voltage is applied, the liquid crystal molecules 30a near the edges of the bus line 18 are tilted due to the alignment regulating force due to the oblique electric field, which may cause light leakage and reduce the contrast ratio. In particular, since a relatively large voltage (OFF voltage) for turning off the TFT is applied to the gate bus line 15 for most of the time, this light leakage does not occur near the edge of the gate bus line 15. It is remarkable.

In the liquid crystal display device 100 of this embodiment, the edge of the bus line 18 near the opening 14a overlapping the bus line 18 is covered with the unit solid portion 14b ′ of the pixel electrode 14, Since the influence of the oblique electric field generated in the vicinity of the edge of 18 is electrically shielded, the liquid crystal molecules 30a of the liquid crystal layer 30 are not tilted by the alignment regulating force due to the oblique electric field. Although the liquid crystal molecules 30a of the liquid crystal layer 30 in the opening 14a overlapping the bus line 18 may be tilted by the electric field generated between the bus line 18 and the counter electrode 22, the bus line 18 is made of a light shielding material. When formed, the opening overlapping the bus line 18 is shielded from light.

Therefore, when the bus line 18 is made of a light-shielding material, the reduction in the contrast ratio due to light leakage during black display is suppressed, and higher quality display is realized.

Further, when the bus line 18 is made of a material having a light shielding property, the occurrence of unevenness (local variation in contrast ratio) in the display surface is suppressed and the display quality is improved, as will be described below. Is improved.

Due to the oblique electric field generated near the edge of the bus line 18, a residual potential is likely to be generated in the opening 14a where the insulating material is exposed, and the inside of the opening 14a close to the bus line 18 is likely to have a residual potential. When the liquid crystal molecules 30a are tilted under the influence of the residual potential, they cause light leakage.
The degree to which the residual potential remains depends on the surface state of the insulating material, but the surface state of the insulating material varies during printing of the alignment film or injection of the liquid crystal material.
Therefore, in the liquid crystal display device, the residual potential varies within the display surface. When the residual potential varies within the display surface, the degree of light leakage varies within the display surface, causing local variations in the contrast ratio and causing unevenness. In particular, since a relatively large voltage is applied to the gate bus line 15 as described above, the gate bus line 15 greatly contributes to the occurrence of the unevenness described above.

In the liquid crystal display device 100 according to the present invention, when the bus line 18 is made of a light-shielding material, the opening 14a overlapping the bus line 18 is shielded by the bus line 18, and therefore, as described above. The occurrence of unevenness is suppressed and the display quality is improved.

Further, the liquid crystal display device 700 shown in FIG.
Then, in the vicinity of the edge of the gate bus line 15, as shown in FIG.
As shown in (a) (corresponding to a sectional view taken along line 15A-15A 'in FIG. 13), the conductive film of the pixel electrode 14 (solid portion 1)
4b) is not formed, and FIG.
3) (corresponding to a sectional view taken along line 15B-15B 'in FIG. 3)) and a region where the conductive film of the pixel electrode 14 is formed are mixed. Therefore, in the region near the edge of the gate bus line 15 where the conductive film (solid portion 14b) is not formed, as shown in FIG.
Impurity ions are adsorbed on the surface of the TFT substrate 100a by the electric field caused by No. 5, and disorder of the alignment occurs due to the electric charges of the adsorbed impurity ions (hereinafter referred to as “accumulated charges”). Therefore, even if the bus line 18 is formed of a material having a light-shielding property, the opening portion in the vicinity of the gate bus line 15 (the region L surrounded by a broken line in FIG. 13).
In L), the disorder of the orientation due to the accumulated charges occurs, and light leakage occurs.

On the other hand, in the liquid crystal display device 100 according to the present invention, the region strongly influenced by the electric field due to the gate bus line 15, that is, in the vicinity of the edge of the gate bus line 15, is shown in FIG. Since there are many regions in which the conductive film (solid portion 14b) of the pixel electrode 14 is formed, as in the above region, occurrence of disorder of orientation due to accumulated charges is suppressed, and light leakage is suppressed.

Impurities that cause accumulated charges are not uniformly distributed in the display surface, but are typically localized in a stripe shape in the display surface. This is because when the liquid crystal material is injected from a plurality of injection ports arranged at a predetermined interval, the impurities are concentrated in the region between the injection ports where the flow velocity becomes slow.

Therefore, since the stripe-shaped regions in which impurities are localized (regions in which the amount of impurities is large) and the other regions (regions in which the amount of impurities are small) differ in the degree of formation of accumulated charges and the degree of escape. The degree of light leakage differs between the streak region and other regions. As a result, in the liquid crystal display device 700 shown in FIG. 13, the stripe-shaped area becomes “black stripes” whose brightness is higher than other areas or “white stripes” whose brightness is lower than other areas, resulting in display unevenness. Cause of.

On the other hand, in the liquid crystal display device 100 according to the present invention, since the occurrence of light leakage due to the accumulated charges is suppressed as described above, the occurrence of display unevenness is also suppressed.

Here, in each of the picture element regions, of the openings 14a close to the bus line 18,
Close to the gate bus line 15 and the unit solid portion 14
The case where the opening 14a located between b'is overlapped with the bus line 18 has been described, but the present invention is not limited to this. Bus line 1 in each of the picture element areas
8 and a part of the openings 14a of the openings 14a located between the unit solid parts 14b ′ are the bus lines 1
By adopting the configuration overlapping with No. 8, the disorder of the alignment of the liquid crystal domain is suppressed, and thereby the reduction of the response speed (deterioration of the response characteristics) and the occurrence of the afterimage phenomenon are suppressed.

From the viewpoint of suppressing the alignment disorder due to the oblique electric field generated near the edge of the bus line 18, the proportion of the opening 14a overlapping the bus line 18 is increased.
That is, it is preferable to cover most of the edge of the bus line 18 with the unit solid portion 14b ′ of the pixel electrode 14.
When the bus line 18 is formed of a light-shielding material, a decrease in the aperture ratio due to increasing this ratio may cause a problem. Therefore, the ratio of the opening 14a overlapping the bus line 18 is desired. It may be set in consideration of the response characteristic and the aperture ratio to be used according to the application of the liquid crystal display device.

Of course, two adjacent unit solid parts 14b '
Not only the opening 14a located between them, but also the bus line 18
The other opening 14a close to may also be configured to overlap the bus line 18. For example, as in the liquid crystal display device 100A shown in FIG. 17, of the plurality of openings 14a of the pixel electrode 14, all of the openings 14a close to the gate bus line 15 are configured to overlap the bus line 18. May be.

In the liquid crystal display device 100 shown in FIG. 12, there is an opening 14a which does not overlap the bus line 18 at the corner of the pixel region (near the intersection of the gate bus line 15 and the source bus line 16). On the other hand, in the liquid crystal display device 100A shown in FIG. 17, the edge of the gate bus line 15 is covered with the unit solid portion 14b ′ even at the corner portion of the pixel region, 1
All of the openings 14a close to 5 overlap the bus line 18.

In the liquid crystal display device 100A shown in FIG. 17, since more of the edge of the bus line 18 is covered by the unit solid portion 14b 'of the pixel electrode 14,
The effect of suppressing the disorder of orientation is high. However, in the case where the opening 14a at the corner of the pixel region is also configured to overlap the bus line 18, the area of the intersection of the gate bus line 15 and the source bus line 16 is smaller than that in the configuration shown in FIG. And the parasitic capacitance may increase. Therefore, the configuration shown in FIG. 17 is preferable from the viewpoint of suppressing the disorder of the orientation, but FIG. 1 is preferable from the viewpoint of reducing the parasitic capacitance.
It can be said that the configuration shown in 2 is preferable. Of course, as shown in FIG. 12, among the openings 14a close to the bus line 18, the opening 14a close to the gate bus line 15 and located between the adjacent unit solid parts 14b ′ is the bus line. If it overlaps with 15, the disorder of the orientation can be sufficiently suppressed, and a sufficiently high display quality can be obtained.

In FIGS. 12 and 17, the gate bus line 15 has a branch portion that projects toward the opening 14a, whereby the opening 14a and the gate bus line 15 overlap each other. However, the present invention is not limited to this. As in the liquid crystal display device 100B shown in FIG. 18, the width of the gate bus line 15 is increased so that the opening 14a close to the gate bus line 15 and the gate bus line 15 overlap with each other (gate bus line 15). 15 may be covered with the unit solid portion 14b ′ of the pixel electrode 14). However, if the width of the gate bus line 15 is increased, the gate bus line 15 will be larger than that shown in FIGS. 12 and 17.
Since the area of the region where the unit solid part 14b 'and the unit solid part 14b' overlap becomes large, the parasitic capacitance between the gate and the drain becomes large.
Further, when the gate bus line 15 is made of a light-shielding material, the aperture ratio is lower than that in the configuration shown in FIGS. Therefore, from the viewpoint of reducing the parasitic capacitance and improving the aperture ratio, the configurations shown in FIGS. 12 and 17 are preferable.

Further, when driving the liquid crystal display device 100,
In general, a larger voltage is applied to the gate bus line 15 than the source bus line 16, so that the oblique electric field generated near the edge of the gate bus line 15 is applied to the liquid crystal molecules of the source bus line 16. It has a greater effect than the oblique electric field generated near the edge.

Therefore, as in the liquid crystal display devices 100 and 100A shown in FIGS. 12 and 17, of the openings 14a close to the bus line, some or all of the openings 14a close to the gate bus line are the bus lines. Line 1
If the configuration that overlaps with 8 (gate bus line 15) is adopted, it is possible to effectively suppress a decrease in response speed and the occurrence of an afterimage phenomenon without causing an unnecessary decrease in aperture ratio.

Of course, a configuration may be adopted in which some or all of the openings 14a close to the source bus line 16 overlap the bus line 18, or the liquid crystal shown in FIGS. 19 and 20. Display devices 100C and 1
As in 00D, all the openings 14a close to the gate bus line 15 and the source bus line 16 may be superposed on the bus line 18. Liquid crystal display devices 100C and 100D shown in FIGS. 19 and 20.
In addition, the source bus line 16 has a branch portion that projects toward the opening 14 a, and not only the opening 14 a close to the gate bus line 15 but also the opening 14 a close to the source bus line 16 are included. It overlaps with the bus line 18.

Further, if necessary, the auxiliary capacitance wiring 17
Alternatively, some or all of the openings 14a adjacent to the bus line 18 may be superposed on the bus line 18.

It is needless to say that the present invention is not limited to the liquid crystal display device having the picture element electrodes 14 illustrated in FIG. 12 and the like, but can be applied to liquid crystal display devices having the picture element electrodes 14 of various shapes. The number and arrangement of the unit solid portions 14b ′ included in the pixel electrode 14 can be variously modified, and the present invention is based on the unit solid portion 1 included in the pixel electrode 14.
It is also suitable for a liquid crystal display device having a relatively small number of 4b ′, for example, a liquid crystal display device in which three unit solid portions 14b ′ are arranged along the extending direction of the source bus line 16 for each picture element region. Used.

The liquid crystal display device 100 of this embodiment described above.
The configuration is the same as that of a known vertical alignment type liquid crystal display device except that the pixel electrode 14 is an electrode having an opening 14a and the bus line 18 has a predetermined shape. And can be manufactured by a known manufacturing method.

In order to vertically align liquid crystal molecules having negative dielectric anisotropy, typically, a vertical alignment film (not shown) is formed on the surface of the pixel electrode 14 and the counter electrode 22 on the liquid crystal layer 30 side. Are formed.

As the liquid crystal material, a nematic liquid crystal material having negative dielectric anisotropy is used. A guest-host mode liquid crystal display device can also be obtained by adding a dichroic dye to a nematic liquid crystal material having negative dielectric anisotropy. The guest-host mode liquid crystal display device does not require a polarizing plate.

Up to this point, the bus line 18 has a predetermined shape (a shape having a branch portion as shown in FIG.
The width of the bus line 18 is made thicker as shown in FIG.
The case of being covered with the solid portion 14b (unit solid portion 14b ') has been described, but the present invention is not limited to this, and the unit solid of the pixel electrode 14 can be performed without changing the shape of the bus line 18. The edge of the bus line 18 may be covered with the solid portion 14b by arranging the portion 14b '(or the opening 14a) in a predetermined arrangement.

For example, as in the liquid crystal display device 100E shown in FIGS. 21A and 21B, the gate bus line 15
In the vicinity of the unit solid part 14b '(the unit solid part 14b
The pixel electrode 14 may be formed so that the shape corresponding to about ½ of b ′) is located. In the liquid crystal display device 100E, the unit solid portion 14b ′ is provided near the gate bus line 15.
Since part of the liquid crystal layer 30 is located, the liquid crystal layer 30 is
4 and a counter electrode 22 are applied with a voltage, a liquid crystal domain having a radial tilt alignment state is formed in a solid portion 14b (a part of the unit solid portion 14b ′) near the gate bus line 15. To form a part.

In the liquid crystal display device 100E, as shown in FIG.
As shown in (a) and (b), the edge of the gate bus line 15 is a part of the unit solid portion 14b ′ (a shape corresponding to about one half of the unit solid portion 14b ′) and these edges. Are covered with a branch portion that electrically connects the. That is,
The edge of the gate bus line 15 is covered with the solid portion 14b of the pixel electrode 14. Therefore, the same effect as that of the liquid crystal display device 100 shown in FIG. 12 can be obtained. Further, in the liquid crystal display device 100E, it is not necessary to form a branch portion in the gate bus line 15 or to increase the width of the gate bus line 15, so that even if the bus line 18 is formed of a light shielding material. There is no unnecessary reduction in the aperture ratio.

Table 2 shows the liquid crystal display device 100E shown in FIGS. 21 (a) and 21 (b) and FIGS. 22 (a) and 22 (b).
The aperture ratio and the aperture ratio (ratio of the aperture ratio of the liquid crystal display device 100E to the aperture ratio of the liquid crystal display device 100F) are shown for the liquid crystal display device 100F provided with the gate bus line 15 having the branch portion as shown in FIG. .

[0159]

[Table 2]

As shown in Table 2, the liquid crystal display device 100
In E, about 1% (0.8% to 1.2%) for any of the 13-inch, 15-inch, 20-inch, and 22-inch liquid crystal panels.
The aperture ratio can be improved to some extent. The values in Table 2 are for certain specifications, and it goes without saying that a higher aperture ratio can be expected depending on the specifications of the liquid crystal display device.

21 (a) and 21 (b) show the case where the edge of the gate bus line 15 is covered with the solid portion 14b of the pixel electrode 14, the gate bus line 15 and the source bus line are shown. It is preferable that at least one edge of 16 is covered with the solid portion 14b of the pixel electrode 14, and the gate bus line 15 and the source bus line 16 are provided as in the liquid crystal display device 100G shown in FIG.
The unit solid portion 14b ′ may be arranged such that both edges of the pixel electrode 14 are covered with the solid portion 14b. In the liquid crystal display device 100G, as shown in FIG. 23, a part of the unit solid portion 14b ′ (a shape corresponding to about one half of the unit solid portion 14b ′) is also provided in the vicinity of the source bus line 16. Therefore, the edge of the source bus line 16 is also covered with the solid portion 14b of the pixel electrode 14.
Therefore, the effect of suppressing the disorder of orientation can be further improved.

Thus, the unit solid part 1 of the pixel electrode 14
By appropriately setting the arrangement of 4b '(of the opening 14a), it is possible to suppress the disorder of the orientation without changing the shape of the bus line 18. 24 (a) and 24 (b) and FIGS. 25 (a) and 25 (b), other liquid crystal display devices 100H and 100I according to the embodiment of the present invention.
Indicates.

In each of the liquid crystal display devices 100H and 100I, the shape of the unit solid portion 14b 'of the pixel electrode 14 has eight sides (edges) and has a rotation axis of four times in the center thereof. It is almost star-shaped. Also, the opening 14a
Is a substantially rhombus.

In the liquid crystal display device 100H, as shown in FIG.
As shown in (a) and (b), the edge of the gate bus line 15 is formed in a zigzag, which causes the edge of the gate bus line 15 to be formed in the pixel electrode 14.
It is covered with the solid portion 14b. On the other hand, in the liquid crystal display device I, as shown in FIGS. 25A and 25B, the gate bus line 15 and the source bus line 16 are provided.
A part (a shape corresponding to about one half) of the substantially star-shaped unit solid portion 14b ′ is arranged in the vicinity of, and as a result, the gate bus line 15 and the source bus line 1
The edges of 6 are covered with the solid portion 14b of the pixel electrode 14. Therefore, in the liquid crystal display device 100I, it is possible to prevent an unnecessary reduction in the aperture ratio.

(Other Embodiments) The structure of one picture element region of a liquid crystal display device 200 according to another embodiment of the present invention will be described with reference to FIGS.
Further, in the following drawings, components having substantially the same functions as those of the liquid crystal display device 200 are designated by the same reference numerals, and the description thereof will be omitted. 26A is a top view seen from the substrate normal direction, and FIG. 26B is FIG.
This corresponds to the cross-sectional view taken along the line 26B-26B 'in (a). FIG. 26B shows a state in which no voltage is applied to the liquid crystal layer.

As shown in FIGS. 26A and 26B, the liquid crystal display device 200 is different from that shown in FIG. 1 in that the TFT substrate 200a has the convex portion 40 inside the opening 14a of the pixel electrode 14. This is different from the liquid crystal display device 100 of the embodiment shown in (a) and (b). A vertical alignment film (not shown) is provided on the surface of the convex portion 40.

The cross-sectional shape of the projection 40 in the in-plane direction of the substrate 11 is the same as the shape of the opening 14a as shown in FIG. 26A, and is substantially star-shaped here. However, the adjacent convex portions 40 are connected to each other, and are formed so as to completely surround the unit solid portion 14b ′ in a substantially circular shape. The cross-sectional shape of the protrusion 40 in the in-plane direction perpendicular to the substrate 11 is shown in FIG.
It is trapezoidal as shown in FIG. That is, the top surface 40t parallel to the substrate surface and the taper angle θ (<9
And a side surface 40s inclined at 0 °. Convex 40
Since a vertical alignment film (not shown) is formed to cover the liquid crystal molecules 3 of the liquid crystal layer 30, the side surface 40s of the convex portion 40 is formed.
0a has an alignment control force in the same direction as the alignment control direction by the oblique electric field, and acts to stabilize the radial tilt alignment.

The operation of the convex portion 40 is shown in FIGS.
Description will be given with reference to (d) and FIGS. 28 (a) and 28 (b).

First, with reference to FIGS. 27A to 27D, the relationship between the alignment of the liquid crystal molecules 30a and the shape of the surface having vertical alignment will be described.

As shown in FIG. 27 (a), the liquid crystal molecules 30a on the horizontal surface are attracted to the surface by the alignment regulating force of the surface having the vertical alignment property (typically, the surface of the vertical alignment film). It is vertically oriented with respect to it. When an electric field represented by an equipotential line EQ perpendicular to the axial direction of the liquid crystal molecules 30a is applied to the liquid crystal molecules 30a in the vertical alignment state, the liquid crystal molecules 30a are rotated in the clockwise or counterclockwise direction. Torque to tilt acts with equal probability. Therefore, in the liquid crystal layer 30 between the parallel plate type electrodes facing each other, liquid crystal molecules 30a that receive a torque in the clockwise direction,
Liquid crystal molecules 30a that receive torque in the counterclockwise direction are mixed. As a result, the change to the alignment state depending on the voltage applied to the liquid crystal layer 30 may not occur smoothly.

As shown in FIG. 27 (b), when an electric field represented by a horizontal equipotential line EQ is applied to the liquid crystal molecules 30a aligned vertically with respect to the inclined surface, The liquid crystal molecules 30a are tilted in a direction (a clockwise direction in the illustrated example) in which the tilt amount is small in order to be parallel to the equipotential line EQ. In addition, as shown in FIG. 27C, the liquid crystal molecules 30a aligned vertically with respect to the horizontal surface are continuously aligned with the liquid crystal molecules 30a aligned vertically with respect to the inclined surface. In the same direction (clockwise) as the liquid crystal molecules 30a located on the inclined surface so that
Lean to.

As shown in FIG. 27D, with respect to a continuous uneven surface having a trapezoidal cross section, the surface should be aligned with the alignment direction regulated by the liquid crystal molecules 30a on each inclined surface. , Liquid crystal molecules 30a on top and bottom
Are oriented.

The liquid crystal display device of the present embodiment stabilizes the radial tilt alignment by making the direction of the alignment control force due to such a shape (projection) of the surface and the alignment control direction due to the oblique electric field coincide with each other. .

28 (a) and 28 (b) show a state in which a voltage is applied to the liquid crystal layer 30 shown in FIG. 26 (b), and FIG. 28 (a) shows that a voltage is applied to the liquid crystal layer 30. 28 schematically shows a state in which the alignment of the liquid crystal molecules 30a starts to change according to the applied voltage (ON initial state).
(B) is a liquid crystal molecule 3 that has changed according to the applied voltage.
The state in which the orientation of 0a reaches a steady state is schematically shown. A curve EQ in FIGS. 28A and 28B shows an equipotential line EQ.

When the pixel electrode 14 and the counter electrode 22 are at the same potential (in the state where no voltage is applied to the liquid crystal layer 30), as shown in FIG. The molecules 30a are oriented perpendicular to the surfaces of both substrates 11 and 21. At this time, the liquid crystal molecules 30a in contact with the vertical alignment film (not shown) on the side surface 40s of the convex portion 40 have the side surface 4
The liquid crystal molecules 30a in the vicinity of the side surface 40s, which are oriented perpendicular to 0s, take an inclined orientation as shown by the interaction with the peripheral liquid crystal molecules 30a (the property as an elastic body).

When a voltage is applied to the liquid crystal layer 30, FIG.
A potential gradient represented by the equipotential line EQ shown in (a) is formed. This equipotential line EQ is the solid part 1 of the pixel electrode 14.
4b and the counter electrode 22, the liquid crystal layer 30 is parallel to the surfaces of the solid portion 14b and the counter electrode 22, and falls in a region corresponding to the opening 14a of the pixel electrode 14 An oblique electric field represented by a tilted equipotential line EQ is formed in the liquid crystal layer 30 on the edge portion (the inner periphery of the opening 14a including the boundary (extension) of the opening 14a) of the portion 14a.

Due to this oblique electric field, as described above,
The liquid crystal molecules 30a on the edge portion EG rotate clockwise in the right edge portion EG in the figure and in the counterclockwise direction in the left edge portion EG in the figure, as indicated by the arrow in FIG. , And are inclined (rotated) and oriented parallel to the equipotential line EQ. The alignment control direction by the oblique electric field is the same as the alignment control direction by the side surface 40s located at each edge portion EG.

As described above, when the change in orientation starting from the liquid crystal molecules 30a located on the inclined equipotential line EQ progresses and reaches a steady state, the orientation state schematically shown in FIG. 28B is obtained. . The liquid crystal molecules 30a located near the center of the opening 14a, that is, near the center of the top surface 40t of the convex portion 40 have substantially the same effect of the alignment of the liquid crystal molecules 30a on the opposite edge portions EG of the opening 14a. Therefore, the liquid crystal molecules 30a in the regions distant from the center of the opening 14a (the top surface 40t of the convex portion 40) are maintained in the alignment state perpendicular to the equipotential line EQ, and the liquid crystal molecules 30a of the nearer edge portion EG The center SA of the opening 14a (the top surface 40t of the protrusion 40) which is inclined under the influence of the orientation of the liquid crystal molecules 30a
Form a tilted orientation that is symmetric with respect to. In addition, the opening 14
Also in the region corresponding to the unit solid portion 14b ′ substantially surrounded by a and the convex portion 40, the unit solid portion 14b
Form a tilted orientation that is symmetrical with respect to the center SA of b '.

As described above, the liquid crystal display device 2 of this embodiment
Also in 00, as in the liquid crystal display device 100, liquid crystal domains having a radial tilt alignment are formed corresponding to the openings 14a and the unit solid portions 14b '. Since the convex portion 40 is formed so as to completely surround the unit solid portion 14b ′ in a substantially circular shape, the liquid crystal domain is formed corresponding to the substantially circular region surrounded by the convex portion 40. Further, the opening 1
The side surface of the convex portion 40 provided inside the opening 4a
Since the liquid crystal molecules 30a near the edge portion EG of a are tilted in the same direction as the alignment direction by the oblique electric field, the radial tilt alignment is stabilized.

The orientation regulating force by the oblique electric field naturally works only when a voltage is applied, and its strength depends on the strength of the electric field (magnitude of applied voltage). Therefore, when the electric field strength is weak (that is, the applied voltage is low), the alignment regulating force due to the oblique electric field is weak, and when an external force is applied to the liquid crystal panel, the radial tilt alignment may be broken due to the flow of the liquid crystal material. Once the radial tilted orientation is broken, the radial tilted orientation is not restored unless a voltage enough to generate an oblique electric field that exerts a sufficiently strong orientation regulating force is applied. On the other hand, the alignment regulating force by the side surface 40s of the convex portion 40 is
It acts regardless of the applied voltage, and is very strong as is known as the anchoring effect of the alignment film. Therefore, even if the liquid crystal material flows and the radial tilt alignment is once broken,
The liquid crystal molecules 30a near the side surface 40s of the convex portion 40 maintain the same alignment direction as in the radial tilt alignment. Therefore, the radial tilted alignment can be easily restored as long as the liquid crystal material stops flowing.

Thus, the liquid crystal display device 20 of the present embodiment.
In addition to the features of the liquid crystal display device 100, 0 has the feature of being strong against external force. Therefore, the liquid crystal display device 200 is suitable for use in a PC or PDA that is easily applied with an external force and is often used while being carried.

When the convex portion 40 is formed by using a highly transparent dielectric material, there is an advantage in that the contribution of the liquid crystal domain formed corresponding to the opening 14a to the display is improved. On the other hand, when the convex portion 40 is formed by using an opaque dielectric material, there is an advantage that light leakage due to the retardation of the liquid crystal molecules 30a that are inclined and oriented by the side surface 340s of the convex portion 40 can be prevented. Which one is adopted may be decided according to the application of the liquid crystal display device.
In either case, when the photosensitive resin is used, the opening 14
There is an advantage that the step of patterning corresponding to a can be simplified. In order to obtain a sufficient alignment control force, the height of the convex portion 40 is about 0.5 when the thickness of the liquid crystal layer 30 is about 3 μm.
It is preferably in the range of μm to about 2 μm. In general,
The height of the convex portion 40 is about 1/6 to about 2 of the thickness of the liquid crystal layer 30.
It is preferably within the range of / 3.

As described above, the liquid crystal display device 200 is
The projection 40 is provided inside the opening 14a of the pixel electrode 14,
The side surface 40 s of the convex portion 40 has liquid crystal molecules 30 a of the liquid crystal layer 30.
On the other hand, it has an alignment regulating force in the same direction as the alignment regulating direction by the oblique electric field. Preferred conditions for the side surface 40s to have an alignment regulating force in the same direction as the alignment regulating direction due to the oblique electric field will be described with reference to FIGS.

29 (a) to 29 (c) schematically show cross-sectional views of the liquid crystal display devices 200A, 200B and 200C, and correspond to FIG. 28 (a). Liquid crystal display device 2
00A, 200B and 200C are all openings 4
Although there is a convex portion inside 0, the arrangement relationship between the entire convex portion 40 as one structure and the opening 40 is the liquid crystal display device 20.
It is different from 0.

In the liquid crystal display device 200 described above,
As shown in FIG. 28A, the convex portion 40 as a structure is formed.
Is entirely formed inside the opening 40a, and
The bottom surface of the protrusion 40 is smaller than the opening 40a. FIG. 29
In the liquid crystal display device 200A shown in (a), the bottom surface of the convex portion 40A coincides with the opening portion 14a.
In the liquid crystal display device 200B shown in (b), the convex portion 40B has a bottom surface larger than the opening portion 14a and is formed so as to cover the solid portion (conductive film) 14b around the opening portion 14a. . These protrusions 40, 40A and 40B
The solid portion 14b is not formed on any of the side surfaces 40s. As a result, as shown in each of the figures, the equipotential line EQ is almost flat on the solid portion 14b and drops in the opening 14a as it is. Therefore, the liquid crystal display device 200
Sides 40 of convex portions 40A and 40B of A and 200B
Similarly to the convex portion 40 of the liquid crystal display device 200 described above, s exerts an alignment regulating force in the same direction as the alignment regulating force by the oblique electric field and stabilizes the radial tilted alignment.

On the other hand, the bottom surface of the convex portion 40C of the liquid crystal display device 200C shown in FIG. 29C is larger than the opening 14a, and the solid portion 14b around the opening 14a has the convex portion 4a.
It is formed on the side surface 40s of 0C. This side 40s
A peak is formed on the equipotential line EQ due to the influence of the solid portion 14b formed above. The peaks of the equipotential line EQ have an inclination opposite to that of the equipotential line EQ that falls at the opening 14a, which generates an oblique electric field opposite to the oblique electric field that causes the liquid crystal molecules 30a to be radially inclined. It indicates that
Therefore, in order for the side surface 40s to have the alignment regulating force in the same direction as the alignment regulating direction by the oblique electric field, it is preferable that the solid portion (conductive film) 14b is not formed on the side surface 40s.

Next, referring to FIG. 30, FIG.
A cross-sectional structure of the protrusion 40 shown in FIG. 7A taken along the line 30A-30A ′ will be described.

As described above, since the convex portion 40 shown in FIG. 26A is formed so as to completely surround the unit solid portion 14b 'in a substantially circular shape, the adjacent unit solid portions 14b' are formed.
The portion of b ′ that plays a role of connecting to each other (branch portion extending in four directions from the circular portion) is formed on the convex portion 40, as shown in FIG. Therefore, in the step of depositing the conductive film that forms the solid portion 14b of the pixel electrode 14, there is a high risk that disconnection will occur on the convex portion 40 or peeling will occur in a later step of the manufacturing process.

Therefore, as in the liquid crystal display device 200D shown in FIGS. 31 (a) and 31 (b), when the independent convex portions 40D are formed so as to be completely included in the opening 14a, the solid portion 14b is formed. Since the conductive film forming the film is formed on the flat surface of the substrate 11, there is no risk of disconnection or peeling. In addition, the convex portion 40D corresponds to the unit solid portion 14b ′.
Is not formed so as to completely enclose it in a substantially circular shape, but a substantially circular liquid crystal domain corresponding to the unit solid portion 14b ′ is formed, and the radial tilt alignment is stabilized as in the previous example. It

The effect of stabilizing the radial tilt alignment by forming the convex portions 40 in the openings 14a is not limited to the openings 14a of the exemplified patterns, and is not limited to the openings 14a of all the patterns described above. It can be applied in the same manner and the same effect can be obtained. In order to sufficiently exert the effect of stabilizing the alignment against the external force by the convex portion 40, the pattern of the convex portion 40 (the pattern when viewed from the substrate normal direction) surrounds the liquid crystal layer 30 in a region as wide as possible. It is preferably shaped. Therefore, for example, the positive pattern having the circular unit solid portion 14b ′ has a greater alignment stabilizing effect by the convex portion 40 than the negative pattern having the circular opening 14a.

As described above, in the electrode structure in which the openings are provided in the pixel electrodes, a sufficient voltage is not applied to the liquid crystal layer in the region corresponding to the openings, and sufficient retardation change cannot be obtained. There may be a problem that the utilization efficiency of the is reduced. Therefore, a dielectric layer is provided on the side of the pixel electrode (upper layer electrode) provided with the opening opposite to the liquid crystal layer, and a further electrode facing at least a part of the opening of the pixel electrode through this dielectric layer. By providing the (lower layer electrode) (two-layer structure electrode), a sufficient voltage can be applied to the liquid crystal layer corresponding to the opening, and the light utilization efficiency and response characteristics can be improved.

FIG. 32 shows a lower layer electrode 12 and an upper layer electrode 14.
And a picture element electrode (two-layer structure electrode) 15 having a dielectric layer 13 provided between them and a liquid crystal display device 30.
0 schematically shows the cross-sectional structure of one picture element region. Picture element electrode 1
The upper electrode 14 of No. 5 is substantially equivalent to the pixel electrode 14 described above, and has openings and solid portions of various shapes and arrangements described above. Below, the pixel electrode 15 having a two-layer structure
The function of is explained.

The pixel electrode 15 of the liquid crystal display device 300 has a plurality of openings 14a (including 14a1 and 14a2). FIG. 32A schematically shows the alignment state (OFF state) of the liquid crystal molecules 30a in the liquid crystal layer 30 to which no voltage is applied. FIG. 32B schematically shows a state in which the alignment of the liquid crystal molecules 30 a starts to change in accordance with the voltage applied to the liquid crystal layer 30 (ON initial state). FIG. 32C schematically shows a state in which the alignment of the liquid crystal molecules 30a changed according to the applied voltage reaches a steady state. Note that in FIG. 32, the openings 14a1 and 14a1
The lower layer electrode 12 provided so as to face the a2 via the dielectric layer 13 overlaps with the openings 14a1 and 14a2, respectively, and is a region between the openings 14a1 and 14a2 (the upper layer electrode 14 is present). However, the arrangement of the lower layer electrode 12 is not limited to this, and the area of the lower layer electrode 12 is equal to the area of the opening 14a for each of the openings 14a1 and 14a2. Alternatively, the area of the lower layer electrode 12 may be smaller than the area of the opening 14a. That is, the lower layer electrode 12 may be provided so as to face at least a part of the opening 14 a with the dielectric layer 13 in between. However, in the configuration in which the lower layer electrode 12 is formed in the opening 14a, a region (gap region) in which neither the lower layer electrode 12 nor the upper layer electrode 14 exists is present in the plane viewed from the normal direction of the substrate 11. Since there is a case in which a sufficient voltage is not applied to the liquid crystal layer 30 in the region facing the gap region, it is necessary to make the width of the gap region sufficiently narrow so as to stabilize the alignment of the liquid crystal layer 30. Preferably, it will typically not exceed about 4 μm. In addition, the upper electrode 1 via the dielectric layer 13
The lower layer electrode 12 formed at a position facing the region where the conductive layer 4 exists does not substantially affect the electric field applied to the liquid crystal layer 30, and thus need not be patterned in particular, but may be patterned. .

As shown in FIG. 32A, the pixel electrode 1
5 and the counter electrode 22 are at the same potential (when no voltage is applied to the liquid crystal layer 30), the liquid crystal molecules 3 in the pixel region are
0a is oriented perpendicular to the surfaces of both substrates 11 and 21. Here, for simplicity, it is assumed that the upper layer electrode 14 and the lower layer electrode 12 of the pixel electrode 15 have the same potential.

When a voltage is applied to the liquid crystal layer 30, FIG.
A potential gradient represented by the equipotential line EQ shown in (b) is formed. In the liquid crystal layer 30 located between the upper electrode 14 of the pixel electrode 15 and the counter electrode 22, a uniform equipotential line EQ parallel to the surfaces of the upper electrode 14 and the counter electrode 22 is formed. A potential gradient is formed. Liquid crystal layer 30 located above openings 14a1 and 14a2 of upper layer electrode 14
, A potential gradient is formed according to the potential difference between the lower layer electrode 12 and the counter electrode 22. At this time, since the potential gradient formed in the liquid crystal layer 30 is affected by the voltage drop due to the dielectric layer 13, the equipotential line EQ formed in the liquid crystal layer 30.
Falls in a region corresponding to the openings 14a1 and 14a2 (a plurality of "valleys" are formed in the equipotential line EQ).
Since the lower layer electrode 12 is formed in a region facing the openings 14a1 and 14a2 via the dielectric layer 13, the upper electrode is also formed in the liquid crystal layer 30 located near the center of each of the openings 14a1 and 14a2. A potential gradient represented by an equipotential line EQ parallel to the surfaces of 14 and the counter electrode 22 is formed (“valley bottom” of the equipotential line EQ). The liquid crystal layer 30 on the edge portion of the openings 14a1 and 14a2 (around the inside of the opening including the boundary (extension) of the openings) EG
An oblique electric field represented by a tilted equipotential line EQ is formed therein.

As is clear from the comparison between FIG. 32B and FIG. 2A, since the liquid crystal display device 300 has the lower electrode 12, the liquid crystal of the liquid crystal domain formed in the region corresponding to the opening 14a. A sufficiently large electric field can be applied to the molecule.

The liquid crystal molecules 30a having a negative dielectric anisotropy are subjected to a torque that tends to align the axial direction of the liquid crystal molecules 30a in parallel with the equipotential line EQ. Therefore, the liquid crystal molecules 30a on the edge portion EG rotate clockwise in the right edge portion EG in the figure and in the counterclockwise direction in the left edge portion EG in the figure, as indicated by the arrow in FIG. 32 (b). Inclining (rotating) in each direction, and oriented parallel to the equipotential line EQ.

As shown in FIG. 32B, the edge portion E of the openings 14a1 and 14a2 of the liquid crystal display device 300.
In G, when an electric field (oblique electric field) represented by an equipotential line EQ inclined with respect to the axial direction of the liquid crystal molecule 30a is generated, the liquid crystal molecule 30a is converted into an equipotential line as shown in FIG. Inclination is performed in a direction (counterclockwise in the illustrated example) in which the amount of inclination to be parallel to the EQ is small. In addition, liquid crystal molecule 3
As shown in FIG. 3C, the liquid crystal molecules 30a located in the region where the electric field represented by the equipotential line EQ perpendicular to the axis direction of 0a are generated on the inclined equipotential line EQ, as shown in FIG. 3C. The liquid crystal molecules 30a are tilted in the same direction as the liquid crystal molecules 30a positioned on the tilted equipotential line EQ so that the alignment is continuous (aligned) with the liquid crystal molecules 30a positioned.

As described above, when the change in the orientation starting from the liquid crystal molecules 30a located on the inclined equipotential line EQ progresses and reaches the steady state, as shown in FIG. A symmetrical tilted orientation (radial tilted orientation) is formed with respect to the center SA of each of the portions 14a1 and 14a2. Further, the liquid crystal molecules 30a on the region of the upper electrode 14 located between the two adjacent openings 14a1 and 14a2 are also aligned with the liquid crystal molecules 30a at the edges of the openings 14a1 and 14a2 ( (To align), tilted orientation. Openings 14a1 and 14
liquid crystal molecule 30a on the portion located at the center of the edge of a2
Are affected by the liquid crystal molecules 30a at the respective edge portions to the same degree, and thus maintain the vertical alignment state similarly to the liquid crystal molecules 30a located at the central portions of the openings 14a1 and 14a2. As a result, the liquid crystal layer on the upper layer electrode 14 is also in the radial tilt alignment state between the two adjacent openings 14a1 and 14a2. However, the openings 14a1 and 14a2
Radial alignment of the liquid crystal layer inside and openings 14a1 and 14a
The tilt direction of liquid crystal molecules is different from the radial tilt direction of the liquid crystal layer between the two. Focusing on the alignment in the vicinity of the liquid crystal molecule 30a located in the center of each of the radially tilted regions shown in FIG. 32C, the openings 14a1 and b are formed.
In 14a2, while the liquid crystal molecules 30a are inclined so as to form a cone that spreads toward the counter electrode,
Between the openings, the liquid crystal molecules 30 are inclined so as to form a cone that spreads toward the upper layer electrode 14. It should be noted that any of the radial tilted alignments is formed so as to match the tilted alignment of the liquid crystal molecules 30a at the edge portion, and thus the two radial tilted alignments are continuous with each other.

As described above, when a voltage is applied to the liquid crystal layer 30, the liquid crystal molecules 30 on the edge portion EG of each of the plurality of openings 14a1 and 14a2 provided in the upper electrode 14.
A radial tilted alignment is formed by starting to tilt from a and then tilting the liquid crystal molecules 30a in the peripheral region to match the tilted alignment of the liquid crystal molecules 30a on the edge portion EG. Therefore, the opening 14 formed in one pixel area
The larger the number of a, the larger the number of the liquid crystal molecules 30a that start to tilt in response to the electric field, and thus the time required to form the radial tilt alignment over the entire pixel region becomes shorter. That is, the response speed of the liquid crystal display device can be improved by increasing the number of openings 14a formed in the pixel electrode 15 for each pixel region. Also, the pixel electrode 1
By using 5 as a two-layer structure electrode having the upper layer electrode 14 and the lower layer electrode 12, a sufficient electric field can be applied to the liquid crystal molecules in the region corresponding to the opening 14a, so that the response characteristics of the liquid crystal display device can be obtained. Is improved.

In order to further stabilize the alignment of the liquid crystal domains having the radial tilt alignment, the liquid crystal molecules are aligned in the radial tilt alignment in cooperation with the alignment control structure of the TFT substrate (the electrode structure having the above-mentioned opening). The convex portions may be provided on the counter substrate.

Convex portion 28 provided on counter substrate 400b
33A and 33B show a liquid crystal display device 400 including the above. 33A is a top view.
33B corresponds to the cross-sectional view taken along the line 33B-33B ′ in FIG.

The liquid crystal display device 400 includes a TFT substrate 100a having a pixel electrode 14 having an opening 14a,
Counter substrate 40 having convex portion 28 protruding toward the liquid crystal layer 30 side
0b and. Note that the TFT substrate 100a is not limited to the configuration illustrated here, and various configurations described above can be appropriately used.

The convex portion 28 provided on the counter substrate 400b
Has a side surface 28 s that is inclined with respect to the substrate surface of the counter substrate 400 b (the substrate surface of the transparent substrate 11), and here the convex portion 28 is formed on the counter electrode 22.

The surface of the convex portion 28 has a vertical alignment property (typically, a vertical alignment film (not shown) is formed so as to cover the convex portion 28), and FIG. ), The liquid crystal molecules 30a are aligned substantially perpendicular to the inclined side surfaces 28s due to the anchoring effect.
Therefore, the liquid crystal molecules 30a around the convex portion 28 are
Radially tilted with 8 as the center. That is, the convex portion 28
Acts to radially orient the liquid crystal molecules 30a by the shape effect of the surface (having vertical orientation).

The convex portion 28 is provided in a region facing the solid portion 14b of the pixel electrode 14, and more specifically, the convex portion 28 is provided so as to face near the center of the unit solid portion 14b '. Has been. By arranging the convex portions 28 in this way, the tilt direction of the liquid crystal molecules by the convex portions 28 is changed so that the unit solid portion 14b ′ of the pixel electrode 14 is formed by the alignment regulation structure.
Aligned with the orientation direction of the radial tilt orientation of the liquid crystal domain formed in the region corresponding to. Since the convex portion 28 exerts an alignment regulating force regardless of whether or not a voltage is applied, a stable radial tilt alignment can be obtained in all display gradations, and it has excellent resistance to stress.

As described above, in the liquid crystal display device 400, when the voltage is applied to the liquid crystal layer 30, that is, the voltage is applied between the pixel electrode 14 and the counter electrode 22, the alignment control structure is formed. The direction of the radial tilted alignment that is formed and the direction of the radial tilted alignment that is formed by the convex portion 28 are aligned, and the radial tilted alignment is stabilized. This state is schematically shown in FIGS. 34 (a) to 34 (c). 34 (a) shows the state when no voltage is applied, FIG. 34 (b) shows the state in which the orientation starts to change after the voltage is applied (ON initial state), and FIG. 34 (c) shows the steady state during voltage application. It is shown schematically.

The alignment regulating force of the convex portion 28 is shown in FIG.
As shown in (a), even in the state where no voltage is applied, it acts on the liquid crystal molecules 30a in the vicinity to form radial tilt alignment.

When a voltage is started to be applied, an electric field indicated by the equipotential line EQ as shown in FIG. 34 (b) is generated (due to the alignment control structure), and the regions corresponding to the opening 14a and the solid portion 14b. A liquid crystal domain in which the liquid crystal molecules 30a are radially inclined and aligned is formed on the surface, and the steady state as shown in FIG. 34C is reached. At this time, the tilt direction of the liquid crystal molecules 30a in the liquid crystal domain formed in the region corresponding to the solid portion 14b matches the tilt direction of the liquid crystal molecules 30a due to the alignment regulating force of the protrusions 28 provided in the corresponding region. To do.

When a stress is applied to the liquid crystal display device 400 in the steady state, the radial tilted alignment of the liquid crystal layer 30 is once broken, but when the stress is removed, the alignment regulating structure and the alignment regulating force of the convex portion 28 are applied to the liquid crystal. Since it acts on the molecule 30a, it returns to the radial tilt alignment state. Therefore, generation of an afterimage due to stress is suppressed.

Since the alignment regulating force by the convex portion 28 has the effect of stabilizing the radial tilted alignment formed by the alignment regulating structure and fixing the central axis position, a strong alignment regulating force is not necessary. . For example, the diameter is about 30
Sufficient alignment regulation force can be obtained by forming the convex portions 28 each having a diameter of about 15 μm and a height (thickness) of about 1 μm with respect to the unit solid portion 14 b ′ of μm to about 50 μm.

The material forming the convex portion 28 is not particularly limited, but it can be easily formed by using a dielectric material such as resin. In addition, when a resin material that is deformed by heat is used, a heat treatment after patterning may be performed, so that FIG.
It is preferable because the convex portion 28 having a gentle hill cross-sectional shape as shown in FIG. As shown in the figure, the convex portion 28 having a smooth shape having a vertex (a cross-sectional shape along the normal line of the substrate surface) has an excellent effect of fixing the center position of the radial tilt alignment. Of course, the convex portion may have a top surface.

Further, in FIG. 33A, the convex portion 28 having a substantially circular sectional shape (the sectional shape along the substrate surface of the counter substrate 400b) is illustrated, but the sectional shape of the convex portion 28 is not limited to this. Instead, it may have a substantially rectangular shape or a substantially cross shape. From the viewpoint of reducing the viewing angle dependence, the cross-sectional shape of the convex portion preferably has high rotational symmetry.

FIG. 35 shows a convex portion 28 having a cross-shaped cross section.
A liquid crystal display device 400A including A is shown. The liquid crystal display device 400A has substantially the same configuration as the liquid crystal display device 400A shown in FIGS. 33A and 33B except that the convex portion 28A has a substantially cross-sectional shape.

The convex portion 28A having a substantially cruciform cross section has a larger area of the inclined side surface exerting the alignment regulating force on the liquid crystal molecules 30a than the convex portion having a substantially circular cross section and occupying the same area. Further, the alignment regulating force can be exerted over a wider range within the liquid crystal domain. Therefore, a larger alignment regulating force can be effectively exerted on the liquid crystal molecules 30a. Therefore, in the liquid crystal display device 400A including the convex portion 28A having a cross shape in cross section, the alignment is further stabilized, and the response speed when a voltage is applied is improved.

Of course, it is also possible to adopt a structure in which convex portions having different cross-sectional shapes (cross-sectional shapes along the substrate surface) are mixed on the counter substrate. For example, in an area where an unnecessary electric field that adversely affects the display is likely to be generated (such as in the vicinity of the bus line), a convex portion having a large alignment regulating force (eg, FIG.
5 is provided with a convex portion 28A) having a substantially cross-shaped cross section,
A convex portion having a cross-sectional shape different from those of the other regions may be provided.

36 and 37 show liquid crystal display devices 400B and 400C having a structure in which convex portions having different cross-sectional shapes are mixed on the counter substrate 400b.

The T of the liquid crystal display device 400B shown in FIG.
Similar to the liquid crystal display device 100E shown in FIGS. 21A and 21B, the FT substrate is a part of the unit solid portion 14b ′ (about 2 of the unit solid portion 14b ′) near the gate bus line 15. The pixel electrode 14 is formed such that the shape corresponding to one-third) is located. The counter substrate of the liquid crystal display device 400B is a unit solid portion 14 near the gate bus line 15.
In a region corresponding to a part of b ′, a convex portion 28B having a substantially T-shaped cross section is provided, and in a region corresponding to the unit solid portion 14b ′, a convex portion 28 having a substantially circular cross-sectional shape is provided. ing.

Liquid crystal molecules 30 formed by the substantially T-shaped convex portion 28B.
The tilt direction of a is the radial tilt alignment of a part of the liquid crystal domain formed in the vicinity of the gate bus line 15 and corresponding to a part of the unit solid part 14b ′ (a shape corresponding to about ½). Align with the orientation direction. The substantially T-shaped convex portion 28B provided corresponding to a part of the unit solid portion 14b '(a shape corresponding to about one half) is provided corresponding to the unit solid portion 14b'. For the same reason as that of the substantially cruciform convex portion 28A, a larger alignment regulating force can be effectively exerted on the liquid crystal molecules 30a.

Therefore, the liquid crystal display device 4 in which the convex portion 28B having a large alignment regulating force is provided near the gate bus line 15
In 00B, the alignment of the liquid crystal molecules 30a near the gate bus line 15 where the alignment is likely to be disturbed can be effectively regulated.

The T of the liquid crystal display device 400C shown in FIG.
Like the liquid crystal display device 100G shown in FIG. 23, the FT substrate has a gate bus line 15 and a source bus line 1
A part of the unit solid part 14b ′ (unit solid part 14b
The pixel electrode 14 is formed so that the shape corresponding to about ½ of b ′) is located. Liquid crystal display device 400C
The counter substrate has a convex portion 28B having a substantially T-shaped cross section in a region corresponding to a part of the unit solid portion 14b ′ near the gate bus line 15 and the source bus line 16, and has a unit solid shape. In a region corresponding to the portion 14b ', there is a convex portion 28 having a substantially circular cross section.

In the liquid crystal display device 400C, since the convex portion 28B having a large alignment regulating force is provided near the gate bus line 15 and the source bus line 16,
Near the gate bus line 15 and the source bus line 16
The alignment of the liquid crystal molecules 30a in the vicinity can be effectively controlled.

(Arrangement of Polarizing Plate and Retardation Plate) A so-called vertical alignment type liquid crystal display device, in which liquid crystal molecules having negative dielectric anisotropy are vertically aligned when no voltage is applied, has various display modes. Can be displayed with. For example, in addition to the birefringence mode in which the birefringence index of the liquid crystal layer is controlled by an electric field, the optical rotation mode or a combination of the optical rotation mode and the birefringence mode is applied to the display mode. By providing a pair of polarizing plates on the outside (opposite side of the liquid crystal layer 30) of the pair of substrates (for example, the TFT substrate and the counter substrate) of all the liquid crystal display devices described in the above embodiments, the birefringence mode liquid crystal is provided. A display device can be obtained.
Moreover, you may provide a phase difference compensation element (typically a phase difference plate) as needed. Furthermore, a bright liquid crystal display device can be obtained even by using substantially circularly polarized light.

(Other Embodiments) The deterioration of the display quality due to the oblique electric field generated near the edge of the bus line is caused by the alignment control structure (unit solid part) for forming the liquid crystal domain having the radial tilt alignment state. And a liquid crystal display device having a vertical alignment type liquid crystal layer that takes a vertical alignment state when no voltage is applied, and liquid crystal display in which the alignment is controlled by the electrode structure having an opening. It occurs in all devices.

By using the present invention, it is possible to improve the display quality in all liquid crystal display devices that have a vertical alignment type liquid crystal layer and control the alignment by an electrode structure having openings.

With reference to FIGS. 38 (a) and 38 (b), a liquid crystal display device 5 according to still another embodiment of the present invention.
The structure of 00 will be described. 38A is a top view seen from the substrate normal direction, and FIG. 38B corresponds to a sectional view taken along the line 38B-38B ′ in FIG. 38A. Figure 38
(A) and (b) have shown the state which applied the voltage to the liquid crystal layer.

The liquid crystal display device 500 includes an active matrix substrate (hereinafter referred to as "TFT substrate") 500a.
And a counter substrate (also referred to as “color filter substrate”) 5
00b and a vertical alignment type liquid crystal layer 30 provided between the TFT substrate 500a and the counter substrate 500b.

The liquid crystal molecules 30a contained in the liquid crystal layer 30 are
A voltage is applied to the liquid crystal layer 30 by a vertical alignment film (not shown) as a vertical alignment layer provided on the surfaces of the TFT substrate 500a and the counter substrate 500b on the liquid crystal layer 30 side having negative dielectric anisotropy. When it is not aligned, it is aligned vertically to the surface of the vertical alignment film.

[0229] The TFT substrate 500a of the liquid crystal display device 500
Has a transparent substrate (eg, glass substrate) 11 and a pixel electrode 19 formed on the surface thereof. Counter substrate 500
b has a transparent substrate (for example, a glass substrate) 21 and a counter electrode 22 formed on the surface thereof. The alignment state of the liquid crystal layer 30 for each pixel region changes according to the voltage applied to the pixel electrode 19 and the counter electrode 22 which are arranged so as to face each other via the liquid crystal layer 30. Display is performed by utilizing a phenomenon in which the polarization state and amount of light passing through the liquid crystal layer 30 changes as the alignment state of the liquid crystal layer 30 changes.

The pixel electrode 19 of the TFT substrate 500a
Has a plurality of openings 19a and a solid portion 19b. The opening 19a refers to a portion of the pixel electrode 19 formed of a conductive film (for example, an ITO film) from which the conductive film is removed, and the solid portion 19b is a portion where the conductive film exists (other than the opening 19a). Part)). A plurality of openings 19a are formed for each picture element electrode, but the solid part 19b is basically formed of a single continuous conductive film.

In this embodiment, each opening 19a has a slit shape (a shape in which the width (the direction perpendicular to the length) is extremely narrow with respect to the length). The plurality of openings 19a are respectively
It has a side extending in a direction of 45 ° with respect to the long side and the short side of the pixel region (column direction and row direction of the matrix array). Also, the upper half and the lower half of the picture element region differ in the direction in which their sides extend by 90 °.

When a voltage is applied between the picture element electrode 19 and the counter electrode 22, the edge portion of the opening 19a of the picture element electrode 19 (on the inner periphery of the opening 19a including the boundary (extension) of the opening 19a) is located. In the liquid crystal layer 30 of FIG.
An oblique electric field represented by is formed. Therefore, the liquid crystal molecules 30a having a negative dielectric anisotropy in a vertical alignment state when no voltage is applied tilts along the tilt direction of the oblique electric field generated at the edge of the opening 19a when a voltage is applied. That is, the liquid crystal layer 30 is alignment-controlled by the oblique electric field generated at the edges of the plurality of openings 19 a of the pixel electrode 19 when a voltage is applied between the pixel electrode 19 and the counter electrode 22. It

In the liquid crystal display device 500, the alignment of the liquid crystal layer 30 is restricted by the oblique electric field generated at the edge of the opening 19a. As a result, when the voltage is applied, the liquid crystal molecules 30a in the pixel region are at 90 ° to each other. It is oriented in four azimuths that form an integral multiple angle. In other words, in the liquid crystal display device 500, the picture element regions are orientation-divided. Therefore, the liquid crystal display device 500 has a good viewing angle characteristic.

The counter substrate 50 of the liquid crystal display device 500.
0b has a convex portion 29 on the surface on the liquid crystal layer 30 side.
The convex portion 29 has an inclined side surface 29s and is formed so as to have a zigzag shape (a dogleg shape) when viewed from the substrate surface normal direction. The direction in which the inclined side surface 29s extends and the direction in which the sides of the opening 19a extend coincide with each other, and the protrusion 29 has two openings 19 adjacent to each other along the width direction of the opening 19a.
It is provided so as to be located approximately in the middle of a.

The surface of the convex portion 29 has a vertical alignment property (typically, a vertical alignment film (not shown) is formed so as to cover the convex portion 29), and the liquid crystal molecules 30a are Due to the anchoring effect of the inclined side surface 29s, the inclined side surface 29s
Oriented almost perpendicular to. When a voltage is applied to the liquid crystal layer 30 in such a state, the inclined side surface 29s of the convex portion 29s is
Other liquid crystal molecules 30a in the vicinity of the convex portion 29 so as to match the tilted orientation on the tilted side surface 29s due to the anchoring effect of
Tilts.

Since the alignment control direction due to the oblique electric field generated at the edge of the opening 19a of the pixel electrode 19 and the alignment control direction due to the convex portion 29 are aligned, the liquid crystal is aligned and divided by the oblique electric field when a voltage is applied. The orientation of the layer is the convex portion 29.
Is further stabilized by.

The TFT substrate 500a of the liquid crystal display device 500
Is a TFT (not shown) as a switching element electrically connected to the pixel electrode 19, and a gate bus line (scanning wiring) 15 and a source bus line (signal wiring) 16 electrically connected to the TFT. Including bus line 18
And have.

In the present embodiment, as shown in FIG. 38A, the opening 19a of the pixel electrode 19 is formed so as not to cross the edge of the gate bus line 15, and the gate bus line 15 has the opening 19a. The edge is covered by the solid portion 19b of the pixel electrode 19. Therefore, high quality display is realized. The reason for this will be described with reference to FIGS. 38A, 38B and 39. In FIG. 39, a part of the edge of the gate bus line 15 is a solid part 1 of the pixel electrode 19.
It is a top view which shows typically the liquid crystal display device 800 which is not covered by 9b.

An oblique electric field is generated near the edge of the bus line 18, and this oblique electric field is generated regardless of the presence or absence of the voltage applied to the liquid crystal layer 30 between the picture element electrode 19 and the counter electrode 22. It Therefore, in a liquid crystal display device that displays a normally black mode, when no voltage is applied,
When the liquid crystal molecules 30a near the edge of the bus line 18 are tilted by receiving the alignment regulating force due to this oblique electric field, light leakage may occur and the contrast ratio may decrease. In particular, the gate bus line 15 has TFTs for most of the time.
Relatively large voltage to turn off the power (off voltage)
Is applied, the light leakage is remarkable in the vicinity of the edge of the gate bus line 15.

In the liquid crystal display device 800, the pixel electrode 19 has the gate bus line 15 as shown in FIG.
Of the gate bus line 15 is not covered with the solid portion 19b of the pixel electrode 19. Therefore, the vicinity of the edge of the gate bus line 15 which is not covered by the solid portion 19b (region LL surrounded by the broken line in FIG. 39)
Then, the liquid crystal molecules 30a are tilted under the influence of the oblique electric field generated near the edge of the gate bus line 15, and light leakage occurs.

Further, due to the oblique electric field generated near the edge of the bus line 18, a residual potential is easily generated in the opening 19a where the insulating material is exposed, and the opening 19a close to the bus line 18 is likely to occur. Liquid crystal molecules 30a inside
If it tilts under the influence of the residual potential, it causes light leakage. The degree to which the residual potential remains depends on the surface state of the insulating material, but the surface state of the insulating material varies during printing of the alignment film or injection of the liquid crystal material. Therefore, in the liquid crystal display device, the residual potential varies within the display surface. If the residual potential varies within the display surface, the degree of light leakage varies within the display surface.
Local variations in the contrast ratio occur, causing unevenness. In particular, since a relatively large voltage is applied to the gate bus line 15 as described above, the gate bus line 15 greatly contributes to the occurrence of the unevenness described above.

In the liquid crystal display device 800, the pixel electrode 19 has the gate bus line 15 as shown in FIG.
Of the gate bus line 15 is not covered with the solid portion 19b of the pixel electrode 19. Therefore, since a region not covered with the conductive film (solid portion 19b) of the pixel electrode 19 exists near the edge of the gate bus line 15, light leakage due to the residual potential occurs in that region,
The display is uneven.

On the other hand, in the liquid crystal display device 500 of this embodiment, the opening 19a of the pixel electrode 19 is formed so as not to cross the edge of the gate bus line 15, and the edge of the gate bus line 15 is formed. Is covered by the solid portion 19b of the pixel electrode 19. Therefore, the influence of the oblique electric field generated near the edge of the gate bus line 18 is electrically shielded (shielded), and the liquid crystal molecules 30a of the liquid crystal layer 30 receive the alignment regulating force by the oblique electric field.
Does not tilt. Therefore, the occurrence of light leakage is suppressed, and the decrease in contrast ratio is suppressed. Further, in the liquid crystal display device 500, the edge of the gate bus line 15 is covered with the solid portion 19b of the pixel electrode 19, and the region near the edge of the gate bus line 15 is a conductive film of the pixel electrode 19 ( Since it is covered with the solid portion 19b), the residual potential is unlikely to occur and unevenness is suppressed. As described above, in the liquid crystal display device 500, the occurrence of light leakage due to the oblique electric field generated in the vicinity of the gate bus line 15 is suppressed, the decrease in the contrast ratio is suppressed, and the residual in the vicinity of the gate bus line 15 is suppressed. Since the occurrence of unevenness due to the potential is suppressed, high-quality display is realized.

In this embodiment, the case where the edge of the gate bus line 15 is covered with the solid portion 19b of the picture element electrode 19 has been described, but as in the liquid crystal display device 500A shown in FIG. The edge of the source bus line 16 may be covered with the solid portion 19b of the pixel electrode 19. Display quality can be improved by covering at least one edge of the gate bus line 15 and the source bus line 16 with the solid portion 19b of the pixel electrode 19. Generally, gate bus line 15
The diagonal electric field generated near the edge of the source bus line 16 has a greater influence on the liquid crystal molecules than the diagonal electric field generated near the edge of the source bus line 16, and therefore at least the edge of the gate bus line 15 is formed in the pixel electrode 19. Solid part 19b
It is preferable to cover with. Further, from the viewpoint of more surely suppressing the influence of the oblique electric field generated near the edge of the bus line 18, as in the liquid crystal display device 500B shown in FIG. 41, the gate bus line 15 and the source bus line 16 are provided.
It is preferable that both edges of the pixel electrode 19 are covered with the solid portion 19b of the pixel electrode 19.

[0245]

In the liquid crystal display device according to the present invention,
The deterioration of the display quality due to the oblique electric field generated near the edge of the bus line is suppressed. Therefore, according to the present invention, a liquid crystal display device having wide viewing angle characteristics and high display quality is provided.

The present invention is suitably used for an active matrix type liquid crystal display device, and is also suitably used for any of a transmissive type, a reflective type and a transflective type liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the structure of one picture element region of a liquid crystal display device 100 according to an embodiment of the present invention, FIG.
Is a top view and (b) is a cross-sectional view taken along the line 1B-1B 'in (a).

2A and 2B are diagrams showing a state in which a voltage is applied to the liquid crystal layer 30 of the liquid crystal display device 100, FIG. 2A schematically showing a state in which the alignment starts to change (ON initial state), and FIG. Shows the steady state schematically.

3A to 3D are diagrams schematically showing the relationship between the lines of electric force and the alignment of liquid crystal molecules.

4A to 4C are diagrams schematically showing alignment states of liquid crystal molecules as seen from a substrate normal direction in a liquid crystal display device 100 according to an embodiment of the present invention.

5A to 5C are diagrams schematically showing an example of radial tilt alignment of liquid crystal molecules.

6A and 6B are top views schematically showing another pixel electrode used in the liquid crystal display device of the embodiment according to the present invention.

7A and 7B are top views schematically showing still another pixel electrode used in the liquid crystal display device according to the embodiment of the present invention.

8A and 8B are top views schematically showing still another pixel electrode used in the liquid crystal display device according to the embodiment of the present invention.

FIG. 9 is a top view schematically showing still another pixel electrode used in the liquid crystal display device according to the embodiment of the present invention.

10A and 10B are top views schematically showing still another pixel electrode used in the liquid crystal display device according to the embodiment of the present invention.

11A is a diagram schematically showing a unit cell of the pattern shown in FIG. 1A, and FIG. 11B is a diagram schematically showing a unit cell of the pattern shown in FIG. And (c)
Is a graph showing the relationship between the pitch p and the solid area ratio.

FIG. 12 is a liquid crystal display device 100 according to an embodiment of the present invention.
FIG. 3 is a top view schematically showing the structure of the picture element region of FIG.

FIG. 13 is a top view schematically showing the structure of a pixel region of a liquid crystal display device 700 in which an opening near a bus line does not overlap the bus line.

14A and 14B show a liquid crystal display device 700.
FIG. 6A is a diagram schematically showing the orientation of liquid crystal molecules near the opening near the gate bus line of FIG.
(B) is a sectional view.

15A is a sectional view taken along line 15A-15A ′ in FIG. 13, and FIG. 15B is a sectional view taken along line 15B-1 in FIG.
FIG. 5B is a cross-sectional view taken along the line 5B ′.

16 (a) and 16 (b) are diagrams schematically showing an alignment state of liquid crystal molecules in the vicinity of an opening close to the gate bus line of the liquid crystal display device 100 of the embodiment according to the present invention. (a) is a top view and (b) is a sectional view.

FIG. 17 is a liquid crystal display device 100 according to an embodiment of the present invention.
It is a top view which shows the structure of the picture element area | region of A typically.

FIG. 18 is a liquid crystal display device 100 according to an embodiment of the present invention.
It is a top view which shows the structure of the picture element area | region of B typically.

FIG. 19 is a liquid crystal display device 100 according to an embodiment of the present invention.
It is a top view which shows the structure of the picture element area | region of C typically.

FIG. 20 is a liquid crystal display device 100 according to an embodiment of the present invention.
It is a top view which shows the structure of the picture element area | region of D typically.

21A is a top view schematically showing the structure of a picture element region of the liquid crystal display device 100E according to the embodiment of the present invention, and FIG. 21B is a diagram showing the vicinity of the gate bus line in FIG. FIG.

22A is a top view schematically showing the structure of a pixel region of a liquid crystal display device 100F according to an embodiment of the present invention, and FIG. 22B is a diagram showing the vicinity of the gate bus line in FIG. FIG.

FIG. 23A is a top view schematically showing the structure of a pixel region of the liquid crystal display device 100G according to the embodiment of the present invention.

24A is a top view schematically showing the structure of a pixel region of a liquid crystal display device 100H according to an embodiment of the present invention, and FIG. 24B is a diagram showing the vicinity of the gate bus line in FIG. FIG.

25A is a top view schematically showing the structure of a picture element region of a liquid crystal display device 100I according to an embodiment of the present invention, and FIG. 25B is a diagram showing the vicinity of the gate bus line in FIG. FIG.

FIG. 26 is a liquid crystal display device 2 according to another embodiment of the present invention.
It is a diagram schematically showing the structure of one picture element region of 00,
(A) is a top view, (b) is 26B-26B 'in (a).
It is sectional drawing which followed the line.

27A to 27D are schematic diagrams for explaining the relationship between the orientation of the liquid crystal molecules 30a and the shape of the surface having vertical orientation.

28A and 28B are diagrams showing a state in which a voltage is applied to the liquid crystal layer 30 of the liquid crystal display device 200, FIG. 28A schematically showing a state in which the orientation starts to change (ON initial state), Is
The steady state is schematically shown.

FIGS. 29A to 29C are liquid crystal display devices 200A and 20A according to the second embodiment, in which the positional relationship between the openings and the projections is different.
It is a schematic sectional drawing of 0B and 200C.

30 is a diagram schematically showing a cross-sectional structure of the liquid crystal display device 200, which is a cross-sectional view taken along the line 30A-30A ′ in FIG. 20 (a).

FIG. 31 is a liquid crystal display device 2 according to another embodiment of the present invention.
It is a figure which shows the structure of one picture element area | region of 00D typically, (a) is a top view, (b) is 31B-31 in (a).
It is sectional drawing which followed the B'line.

32 is a diagram schematically showing a cross-sectional structure of one pixel region of a liquid crystal display device 300 including a two-layer structure electrode, FIG.
Shows a state in which no voltage is applied, (b) shows a state where the orientation starts to change (ON initial state), and (c) shows a steady state.

FIG. 33 is a liquid crystal display device 40 having a convex portion on a counter substrate.
It is a figure which shows typically the structure of one picture element area | region of 0,
(A) is a top view, (b) is 33B-33B 'in (a).
It is sectional drawing which followed the line.

34A and 34B are diagrams schematically showing a cross-sectional structure of one pixel region of the liquid crystal display device 400, in which FIG. 34A shows a state in which no voltage is applied, and FIG. Status)
And (c) shows the steady state.

FIG. 35 is a top view schematically showing the structure of one picture element region of another liquid crystal display device 400A having convex portions on the counter substrate.

[Fig. 36] Fig. 36 is a top view schematically showing the structure of one picture element region of another liquid crystal display device 400B having convex portions on the counter substrate.

FIG. 37 is a top view schematically showing the structure of one picture element region of another liquid crystal display device 400C having a protrusion on the counter substrate.

38A and 38B are diagrams schematically showing the structure of one picture element region of a liquid crystal display device 500 according to still another embodiment of the present invention, wherein FIG. 38A is a top view and FIG. 38B-3
FIG. 8B is a sectional view taken along the line 8B ′.

FIG. 39 is a top view schematically showing a liquid crystal display device 800 in which a part of the edge of the gate bus line is not covered by the solid part of the pixel electrode.

FIG. 40 is a top view schematically showing the structure of one picture element region of a liquid crystal display device 500A according to still another embodiment of the present invention.

41 is a top view schematically showing the structure of one picture element region of a liquid crystal display device 500B according to still another embodiment of the present invention. FIG.

[Explanation of symbols]

11, 21 Transparent insulating substrates 14, 14A, 14B, 14C, 14D, 14E, 14
F picture element electrode 14G, 14H, 14I picture element electrode 14a opening 14b solid part (conductive film) 14b 'unit solid part 19 picture element electrode 19a opening 19b solid part (conductive film) 22 counter electrode 30 liquid crystal layer 30a Liquid crystal molecules 40, 40A, 40B, 40C, 40D Convex portion 40s Convex side surface 40t Convex portion top surface 100a, 200a, 500a TFT substrate (active matrix substrate) 100b, 400b, 500b Counter substrate (color filter substrate) 100 , 100A, 100B, 100C, 100D Liquid crystal display devices 100E, 100F, 100G, 100H, 100I
Liquid crystal display device 200, 200A, 200B, 200C, 200D Liquid crystal display device 300, 400, 400A, 400B, 400C Liquid crystal display device 500, 500A, 500B Liquid crystal display device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Ochi             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Keizo Watanabe             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F term (reference) 2H090 HD14 KA05 KA08 LA01 LA04                       MA01 MA07 MA15                 2H092 GA13 HA04 JA24 JB64 NA01                       NA04 NA28 PA09 PA10 PA11

Claims (10)

[Claims] 1. A first substrate, a second substrate, a liquid crystal layer provided between the first substrate and the second substrate, and a plurality of pixel regions for displaying. On the liquid crystal layer side, the first substrate is provided with a picture element electrode provided for each of the plurality of picture element regions, a switching element electrically connected to the picture element electrode, and an electrical connection to the switching element. A bus line including a gate bus line and a source bus line connected to the second substrate, the second substrate has a counter electrode facing the pixel electrode via the liquid crystal layer, and the pixel electrode is A plurality of openings, and a solid part composed of a plurality of unit solid parts, wherein in each of the plurality of pixel regions, the liquid crystal layer is between the pixel electrode and the counter electrode. It takes a vertical alignment state when no voltage is applied, and When a voltage is applied between the counter electrode and,
A plurality of liquid crystal domains each having a radial tilt alignment state are formed in the plurality of openings and the solid portion by an oblique electric field generated at an edge portion of the plurality of openings of the pixel electrode, and applied. A liquid crystal display device that performs display by changing the alignment state of the plurality of liquid crystal domains according to the applied voltage, wherein each of the plurality of pixel regions has a plurality of openings of the pixel electrode. Of which, close to the bus line,
The liquid crystal display device, wherein at least one of the openings located between two adjacent unit solid parts of the plurality of unit solid parts overlaps with the bus line. 2. A first substrate, a second substrate, a liquid crystal layer provided between the first substrate and the second substrate, and a plurality of picture element regions for displaying. On the liquid crystal layer side, the first substrate is provided with a picture element electrode provided for each of the plurality of picture element regions, a switching element electrically connected to the picture element electrode, and an electrical connection to the switching element. A bus line including a gate bus line and a source bus line connected to the second substrate, the second substrate has a counter electrode facing the pixel electrode via the liquid crystal layer, and the pixel electrode is A plurality of openings, and a solid part formed of a plurality of unit solid parts each surrounded by at least a part of the openings, the liquid crystal layer, the liquid crystal layer, the pixel electrode Vertical alignment state when no voltage is applied between the counter electrode and the counter electrode Taking a liquid crystal display device, in each of the plurality of picture element regions, among the plurality of apertures of the pixel electrode, proximate to said bus line,
The liquid crystal display device, wherein at least one of the openings located between two adjacent unit solid parts of the plurality of unit solid parts overlaps with the bus line. 3. The liquid crystal display device according to claim 1, wherein the at least one opening overlapping the bus line includes at least an opening near the gate bus line. 4. The liquid crystal display device according to claim 3, wherein among the plurality of openings of the pixel electrode, all of the openings adjacent to the gate bus line overlap the bus line. 5. The liquid crystal display device according to claim 3, wherein the at least one opening that overlaps the bus line further includes an opening that is close to the source bus line. 6. A first substrate, a second substrate, a liquid crystal layer provided between the first substrate and the second substrate, and a plurality of picture element regions for displaying. On the liquid crystal layer side, the first substrate is provided with a picture element electrode provided for each of the plurality of picture element regions, a switching element electrically connected to the picture element electrode, and an electrical connection to the switching element. A bus line including a gate bus line and a source bus line connected to the second substrate, the second substrate has a counter electrode facing the pixel electrode via the liquid crystal layer, and the pixel electrode is , A plurality of openings, and a solid part, in each of the plurality of picture element regions, the liquid crystal layer, when a voltage is not applied between the picture element electrode and the counter electrode. It is in a vertical alignment state, and between the picture element electrode and the counter electrode. When pressure is applied,
A liquid crystal display device in which alignment is regulated by an oblique electric field generated at edge portions of the plurality of openings of the pixel electrode, wherein the gate bus line and the source bus are provided in each of the plurality of pixel regions. The liquid crystal display device, wherein at least one edge of the line is covered by the solid portion of the pixel electrode. 7. The liquid crystal display device according to claim 6, wherein in each of the plurality of picture element regions, at least an edge of the gate bus line is covered by the solid portion of the picture element electrode. 8. The solid part of the picture element electrode comprises a plurality of unit solid parts, and in each of the plurality of picture element regions, the liquid crystal layer is composed of the picture element electrode and the counter electrode. When a voltage is applied between the pixel electrodes, a diagonal electric field is generated at the edges of the openings of the pixel electrode, so that the plurality of openings and the solid portion each have a radial tilt alignment state. The liquid crystal display device according to claim 6 or 7, wherein a plurality of liquid crystal domains are formed, and display is performed by changing alignment states of the plurality of liquid crystal domains according to an applied voltage. 9. In each of the plurality of picture element regions, of the plurality of openings of the picture element electrode, two units adjacent to the bus line and adjacent to the plurality of unit solid portions are adjacent to each other. At least one of the openings located between the solid parts
9. The liquid crystal display device according to claim 8, wherein the liquid crystal display device overlaps with the bus line. 10. The liquid crystal layer, when a voltage is applied between the picture element electrode and the counter electrode, is radially tilted to the solid portion near the bus line by the oblique electric field. The liquid crystal display device according to claim 8, which forms a part of a liquid crystal domain that takes a state.