JP2014077917A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element which suppresses degradation in the display quality.SOLUTION: A liquid crystal display element 101 has a reed-shaped common electrode 106, a reed-shaped segment electrode 107 orthogonal to the common electrode, and a liquid crystal layer interposed between the electrodes and forming a pretilt angle in a predetermined direction to align a liquid crystal in a substantially vertical direction; and in a pixel 114, the display element has a normal region where the liquid crystal is tilted in a direction where the pretilt angle is formed by application of a voltage between the common electrode 106 and the segment electrode 107. In an abnormal region near an edge of the pixel 114 where the liquid crystal is tilted in a direction different from the direction in the normal region by application of the voltage, a small opening as a punched part of the electrode is formed in at least one of the common electrode 106 and the segment electrode 107.

Description

  The present invention relates to a liquid crystal display element.

  The liquid crystal display element includes a transmissive type and a reflective type. For example, in the case of a transmissive type, a transparent first substrate disposed on the viewer side, and an observer facing the first substrate. Has a transparent second substrate disposed on the opposite side, and a liquid crystal layer is sandwiched between the first substrate and the second substrate. The liquid crystal layer can be formed using, for example, nematic liquid crystal (hereinafter also referred to as nematic liquid crystal). Then, an electrode made of a transparent conductive material such as ITO (Indium Tin Oxide) with necessary patterning is provided on the inner surface on the liquid crystal layer side of the first substrate and / or the second substrate. be able to. A liquid crystal alignment film that realizes uniform initial alignment of the liquid crystal in the liquid crystal layer can be provided on the surface of the electrode on each substrate in contact with the liquid crystal layer. A pair of polarizing plates can be arranged on the viewer side and the opposite side with both the first substrate and the second substrate sandwiching the liquid crystal layer interposed therebetween. In the liquid crystal display device having such a configuration, the liquid crystal of the liquid crystal layer changes its orientation from the initial alignment state in accordance with the electric field applied to the liquid crystal layer using the electrode, and the light transmitted through the liquid crystal layer is controlled. Made.

  Liquid crystal display elements are classified into several modes (types) based on the initial alignment state of the liquid crystal in the liquid crystal layer and the operation when an electric field is applied. For example, there is a liquid crystal display element in which the liquid crystal of the liquid crystal layer in the initial alignment where no electric field is applied is vertically aligned or approximately perpendicular to the substrate surface. Such a liquid crystal display element is referred to as a VA (Vertical Alignment) type liquid crystal display element.

  In the VA liquid crystal display element, a liquid crystal having negative dielectric anisotropy is used for forming a liquid crystal layer. A pair of polarizing plates is disposed on the first and second substrates so as to form a crossed Nicol, usually with a liquid crystal layer interposed therebetween. Electrodes are provided on the inner surfaces of the first and second substrates on the liquid crystal layer side. When a voltage is applied to the liquid crystal layer using the electrode, the orientation of the liquid crystal in the liquid crystal layer changes, and the orientation of the liquid crystal tends to be perpendicular to the electric field where the liquid crystal is formed, that is, the orientation of the liquid crystal is parallel to the substrate. (For example, refer to Patent Document 1). Thereby, in the portion where voltage is applied, light transmission determined by the product (Δn · d) of the refractive index anisotropy (Δn) of the liquid crystal and the thickness (d) of the liquid crystal layer, compared to the initial alignment state of the liquid crystal. The characteristic changes. In the VA liquid crystal display element, a desired display is performed by utilizing the property that the light transmission characteristic changes in the voltage application portion.

  The VA liquid crystal display element has excellent response characteristics and can realize a high contrast display as compared with a TN (Twisted Nematic) type liquid crystal display element or an STN (Super Twisted Nematic) type liquid crystal display element ( For example, see Patent Document 2.) VA-type liquid crystal display elements are actively used for, for example, display devices for liquid crystal televisions and portable information devices, and so-called in-vehicle devices such as instrument panels for vehicles such as automobiles.

  In such a VA liquid crystal display element, as described above, the liquid crystal in the liquid crystal layer in the initial alignment is vertically aligned or substantially perpendicular to the substrate surface. However, it may not be desirable for the liquid crystal to be perfectly vertically aligned. When the orientation of the liquid crystal when no voltage is applied is completely perpendicular to the substrate, the direction in which the liquid crystal tilts cannot be defined when a voltage in a direction completely perpendicular to the substrate surface is applied. As a result, the orientation of the liquid crystal during voltage application is not uniform and the display quality is degraded. Therefore, in the VA liquid crystal display element, the direction in which the vertically aligned liquid crystal is tilted by applying a voltage by giving a pretilt angle to the liquid crystal in the liquid crystal layer or devising the electrode shape by some method is used. It is necessary to specify.

As a method for forming the pretilt angle of the liquid crystal in the liquid crystal layer, there is an oblique deposition method in which silicon oxide (SiO ₂ ) is obliquely deposited with respect to the substrate. Further, as a simpler method, there is a method in which a liquid crystal alignment film is provided on the surface on the liquid crystal layer side of each substrate sandwiching the liquid crystal layer, and the liquid crystal alignment film is subjected to alignment treatment. For example, a pre-tilt angle can be given to the vertically aligned liquid crystal by using a vertical alignment liquid crystal alignment film and performing a rubbing treatment. Then, it is possible to define the alignment direction of the liquid crystal that is substantially vertically aligned, that is, the formation direction of the pretilt angle of the liquid crystal.

JP 2003-207782 A JP 2006-11362 A

  In applications that require high-definition display, such as liquid crystal televisions and display devices for portable information devices, full-dot display in which pixels are arranged in a matrix in the vertical and horizontal directions is required. When full-dot display is performed using a VA liquid crystal display element, the liquid crystal display element can be configured as follows. That is, the liquid crystal display element is formed in a strip shape extending in a vertical direction perpendicular to the first electrode, and a first substrate having a plurality of first electrodes formed in a strip shape extending in the horizontal direction (left-right direction). Sandwiched between the second substrate having the plurality of second electrodes formed, the first electrode formation surface of the first substrate and the second electrode formation surface of the second substrate, and in a predetermined direction between the electrodes And a liquid crystal layer in which the liquid crystal is substantially vertically aligned by forming a pretilt angle.

  In the liquid crystal display element having the above-described structure, each overlapping portion of the first electrode and the second electrode forms a pixel, enabling full dot display and enabling desired high-definition image display. .

However, in the VA type liquid crystal display element having the above-described structure, when full dot display is performed, the alignment of the liquid crystal may be disturbed in the peripheral portion of the pixel.
In the case of the liquid crystal display element having the above structure, each pixel is an overlapping portion of the first electrode and the second electrode, and is an area surrounded by the edge of the first electrode and the edge of the second electrode. Become.
Therefore, the peripheral portion of each pixel close to the edge of the first electrode or the edge of the second electrode may be affected by an oblique electric field from the edge, and liquid crystal alignment may be disturbed. Such a disorder in the alignment of the liquid crystal may generate a domain in a pixel that performs display, which may cause unevenness of display and may deteriorate the display quality of the liquid crystal display element.

  Therefore, in a VA liquid crystal display element that performs full-dot display, there is a demand for a technique that reduces display unevenness due to disorder of alignment and occurrence of domains, and suppresses deterioration in display quality of the liquid crystal display element.

  The present invention has been made in view of these points. That is, an object of the present invention is to reduce display irregularity due to disorder of alignment of liquid crystals in a pixel and domains in a VA liquid crystal display element. And the objective of this invention is providing the liquid crystal display element which suppressed the fall of the display quality.

  Other objects and advantages of the present invention will become apparent from the following description.

The present invention includes a plurality of strip-shaped first electrodes extending in a first direction, a plurality of strip-shaped second electrodes extending in a second direction so as to be orthogonal to the first electrode,
A liquid crystal layer that is sandwiched between the first electrode and the second electrode and forms a pretilt angle in a predetermined direction so that the liquid crystal is substantially vertically aligned;
In a pixel that is an overlapping portion of the first electrode and the second electrode, a first region in which the liquid crystal is inclined in the pretilt angle forming direction by applying a voltage between the first electrode and the second electrode is provided. A liquid crystal display element,
An opening of a small piece formed in at least one of the first electrode and the second electrode is formed in a second region where the liquid crystal is inclined in a direction different from the first region by voltage application near the edge of the pixel. The present invention relates to a liquid crystal display element.

  In the present invention, it is preferable that the opening has a size that does not prevent the liquid crystal from being inclined by applying a voltage between the first electrode and the second electrode.

  In the present invention, the opening has a width in the range of 3 μm to 6 μm, and the shape is preferably rectangular or circular.

  In the present invention, a plurality of openings are arranged, and the arrangement interval of the openings is in the range of 3 μm to 20 μm in the pretilt angle forming direction and in the range of 4 μm to 20 μm in the direction orthogonal to the pretilt angle forming direction. It is preferable to be within.

In the present invention, the formation direction of the pretilt angle of the liquid crystal coincides with one of the first direction and the second direction,
The opening is preferably arranged in the vicinity of an edge located in a direction opposite to the direction in which the liquid crystal of the pixel is tilted, among edges located in a direction perpendicular to the pretilt angle forming direction of the pixel.

In the present invention, the formation direction of the pretilt angle of the liquid crystal coincides with one of the first direction and the second direction,
The opening is preferably disposed in the vicinity of the edge of the pixel located in a direction parallel to the direction in which the pretilt angle is formed.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display element which suppressed the fall of display quality is provided.

It is a top view which shows typically a part of electrode structure of the VA-type liquid crystal display element which performs a full dot display. It is a figure which shows typically the cross section of the left-right direction of the pixel of the liquid crystal display element of FIG. It is a figure which shows typically the cross section of the up-down direction of the pixel of the liquid crystal display element of FIG. It is a top view which shows typically the orientation state of the liquid crystal of the pixel of a liquid crystal display element. It is sectional drawing which illustrates typically the structure of the liquid crystal display element of 1st Embodiment of this invention. It is a figure explaining the relationship between the direction of the alignment process of the liquid crystal aligning film in the liquid crystal display element of 1st Embodiment of this invention, and the absorption axis of a polarizing plate. It is a top view which shows typically a part of electrode structure of the liquid crystal display element of 1st Embodiment of this invention. It is a top view which shows typically the orientation state of the liquid crystal of the pixel of the liquid crystal display element of 1st Embodiment of this invention. It is a figure which shows typically the electrode structure of the pixel of the liquid crystal display element of 1st Embodiment of this invention. It is sectional drawing which illustrates typically the structure of the liquid crystal display element of 2nd Embodiment of this invention. It is a top view which shows typically a part of electrode structure of the liquid crystal display element of 2nd Embodiment of this invention. It is a figure which shows typically the electrode structure of the pixel of the liquid crystal display element of 2nd Embodiment of this invention.

As described above, in a VA liquid crystal display element that performs full-dot display, there is a demand for a technique that suppresses deterioration in display quality due to a domain generated in a pixel.
The present inventor has intensively studied to meet such a demand.

  FIG. 1 is a plan view schematically showing a part of an electrode structure of a VA liquid crystal display element that performs full dot display.

  A conventionally known VA-type liquid crystal display element 1 that performs full-dot display is a common electrode that is a plurality of first electrodes that are disposed on the front side that is an observer side and are formed in a strip shape that extends in the horizontal direction. And a segment electrode which is a plurality of second electrodes which are arranged on the back side of the first substrate and which are formed in a strip shape extending in the vertical direction perpendicular to the common electrode 2 And a second substrate (not shown) having 3. The liquid crystal display element 1 is sandwiched between the common electrode 2 formation surface of the first substrate and the segment electrode 3 formation surface of the second substrate, and forms a pretilt angle in a predetermined direction between the electrodes to form liquid crystal (illustrated). The liquid crystal layer (not shown) is substantially vertically aligned. The liquid crystal in the liquid crystal layer is a liquid crystal having negative dielectric anisotropy (Δε).

  In the liquid crystal display element 1, it is possible to dispose a vertically aligned liquid crystal alignment film (not shown) between the common electrode 2 on the first substrate and the liquid crystal layer. The liquid crystal alignment film can be subjected to an alignment process, for example, from the upper side to the lower side of the drawing in a state of being provided in the liquid crystal display element 1 of FIG. Similarly, in the liquid crystal display element 1, a vertical alignment liquid crystal alignment film (not shown) can be disposed between the segment electrode 3 on the second substrate and the liquid crystal layer, from the bottom to the top of the figure. Orientation treatment can be performed. In the liquid crystal display element 1 of FIG. 1, such a liquid crystal alignment film is provided, and a pretilt angle is formed in a desired direction to realize a structure in which the liquid crystal is substantially vertically aligned.

  In FIG. 1, only the direction of the alignment treatment of the liquid crystal alignment film is indicated by an arrow, the solid line arrow pointing downward indicates the direction of the alignment treatment of the liquid crystal alignment film on the common electrode 2 side, and the broken line pointing upward An arrow indicates the direction of alignment treatment of the liquid crystal alignment film on the segment electrode 3 side.

  In the liquid crystal display element 1, an F polarizing plate (not shown) is disposed on the front side opposite to the common electrode 2 side of the first substrate, and the opposite side of the second substrate opposite to the segment electrode 3 side. An R polarizing plate (not shown) is arranged on the back side. The pair of polarizing plates are arranged so that the absorption axes thereof are orthogonal to each other with the above-described liquid crystal layer interposed therebetween. Moreover, in the liquid crystal display element 1, it is preferable to provide a backlight (not shown) on the back side of the R polarizing plate.

  In the liquid crystal display element 1, a plurality of common electrodes 2 having a predetermined line width L1 are arranged so as to be separated from each other with a predetermined line distance L2, and similarly, with a predetermined line width L3. The plurality of segment electrodes 3 are arranged so as to be separated from each other with a predetermined line-to-line distance L4. As a result, in the liquid crystal display element 1 in a plan view as shown in FIG. 1, each overlapping portion of the common electrode 2 and the segment electrode 3 constitutes one pixel 4. The liquid crystal display element 1 enables full dot display using the pixels 4 arranged in a matrix form of upper, lower, left, and right, and enables desired high-definition image display.

  At this time, as shown in FIG. 1, each pixel 4 of the liquid crystal display element 1 is formed as a region where the common electrode 2 having two edges and the segment electrode 3 having two edges overlap. Therefore, when a bright display is performed by applying an ON voltage between the common electrode 2 and the segment electrode 3 (hereinafter also simply referred to as ON), the edge of the common electrode 2 and the edge of the segment electrode 3 are displayed. Affected by. That is, the orientation of the liquid crystal when ON is affected by the oblique electric field from the edge of the common electrode 2 and the edge of the segment electrode 3.

  FIG. 2 is a diagram schematically showing a cross section in the left-right direction of the pixel of the liquid crystal display element of FIG.

  As shown in FIG. 2, the pixel 4 is formed as a portion where the common electrode 2 on the upper layer side and the segment electrode 3 on the lower layer side overlap with the liquid crystal layer 5 interposed therebetween. In the region near the center of the pixel 4, the liquid crystal 6 is oriented toward the back side (back side) of the drawing (paper surface) at the time of ON due to the effect of the orientation treatment described above.

  On the other hand, in the peripheral portion of the pixel 4 of the liquid crystal display element 1, the liquid crystal 6 may be oriented differently from the above when it is turned on. As shown in FIG. 2, the width of the segment electrode 3 located on the lower layer side across the liquid crystal layer 5 in the cross section in the left-right direction of the region including the pixel 4 of the liquid crystal display element 1 is common to the upper layer side. This is caused by being smaller than the width of the electrode 2. That is, due to the difference in width, an unintended oblique electric field 7 is formed between the edge of the segment electrode 3 and the common electrode 2 as shown in FIG. As described above, the liquid crystal 6 of the liquid crystal layer 5 has negative dielectric anisotropy. Therefore, the liquid crystal 6 located near the edge of the segment electrode 3 of the pixel 4 and affected by the oblique electric field 7 generated therefrom tends to be tilted in an orthogonal direction with respect to the oblique electric field 7.

As a result, in the vicinity of the left and right end portions of the pixel 4 of the liquid crystal display element 1, due to the influence of the oblique electric field 7 due to the edge of the segment electrode 3, the liquid crystal display element 1 is oriented in parallel with the horizontal direction of the drawing when ON.
In FIG. 2, the direction in which the liquid crystal 6 is tilted by the oblique electric field 7 is indicated by a curved arrow indicating a tilt direction. This also applies to FIG. 3 described later.

  FIG. 3 is a diagram schematically showing a vertical section of a pixel of the liquid crystal display element of FIG.

  Similarly, as shown in FIG. 3, the width of the common electrode 2 positioned on the upper layer side with the liquid crystal layer 5 interposed therebetween is positioned on the lower layer side in the vertical section of the region including the pixel 4 of the liquid crystal display element 1. It becomes smaller than the width of the segment electrode 3. Therefore, due to the difference in width, an unintended oblique electric field 8 is formed between the edge of the common electrode 2 and the segment electrode 3 as shown in FIG. As a result, the liquid crystal 6 located near the edge of the common electrode 2 of the pixel 4 and affected by the oblique electric field 8 generated therefrom tends to be aligned in a direction perpendicular to the oblique electric field 8. That is, in the peripheral portion of the pixel 4, the peripheral portion located on the right side of FIG. 3 is affected by the oblique electric field 8 due to the edge of the common electrode 2, and the orientation change inclined in the right direction of FIG. Then, it tries to be oriented horizontally on the electrode surface.

  In addition, the alignment change of the liquid crystal 6 in the vicinity of the edge of the common electrode 2 at the time of ON is similar to the alignment change due to the effect of the alignment process described above. That is, it is the same as the orientation change that falls in the pretilt angle forming direction near the center of the pixel 4. Accordingly, the alignment disorder of the liquid crystal 6 does not occur near the edge of the common electrode 2 of the pixel 4 described above, and there is no problem in the liquid crystal display element 1. In that case, the problem is the change in the orientation of the liquid crystal 6 in the vicinity of the edge located on the left side of FIG. That is, in the vicinity of the pixel 4 in the vicinity of the left end portion in FIG. 3, it is affected by the oblique electric field 8 due to the edge of the common electrode 2 and changes its orientation inclining to the left in FIG. Thus, it tries to be oriented horizontally on the electrode surface. The direction of the alignment change of the liquid crystal 6 at the ON time is 180 ° different from the direction of the alignment change due to the effect of the alignment process described above.

  In the pixel 4, the edge of the common electrode 2 at the right end in FIG. 3 is the entry side (entrance side) of the rubbing means when the alignment treatment of the liquid crystal alignment film on the common electrode 2 is the rubbing treatment by the rubbing means. ) And end. Then, the end of the pixel 4 on the side where the liquid crystal 6 is tilted when turned on by the effect of the alignment treatment of the liquid crystal alignment film. On the other hand, in the pixel 4 of FIG. 3, the edge of the common electrode 2 at the left end is the exit side from which the rubbing means exits in the rubbing process. Then, the end of the pixel 4 on the side opposite to the side where the liquid crystal 6 falls when turned ON by the effect of the alignment treatment of the liquid crystal alignment film.

  In FIG. 3, the direction of the alignment process is indicated by an arrow, the solid line arrow pointing to the left side indicates the direction of the alignment process of the liquid crystal alignment film on the common electrode 2 side, and the broken line arrow pointing to the right side is the segment electrode 3. The direction of the alignment treatment of the liquid crystal alignment film on the side is shown.

  FIG. 4 is a plan view schematically showing the alignment state of the liquid crystal of the pixel of the liquid crystal display element.

  As described above, in the pixel 4 of the liquid crystal display element 1, the liquid crystal layer 5 (see FIG. 4) when turned on due to the influence of the oblique electric fields 7 and 8 (not shown in FIG. 4) when turned on in FIGS. 2 and 3. The alignment direction of the liquid crystal 6 is not uniform and may include various alignment states. FIG. 4 schematically illustrates various alignment states of the liquid crystal 6 that may occur in the pixel 4 when the liquid crystal display element 1 is ON. In FIG. 4, arrows are used to schematically show the liquid crystal 6 and its tilt direction.

  In FIG. 4, only the direction of alignment treatment of the liquid crystal alignment film (not shown) of the pixel 4 is indicated by an arrow, and the solid line arrow pointing downward is the common electrode 2 on the upper layer side with the liquid crystal layer 5 interposed therebetween. (Not shown in FIG. 4) The direction of the alignment treatment of the liquid crystal alignment film on the side is shown. A broken-line arrow pointing upward indicates the direction of the alignment treatment of the liquid crystal alignment film on the segment electrode 3 (not shown in FIG. 4) side on the lower layer side with the liquid crystal layer 5 interposed therebetween.

  As shown in FIG. 4, in the pixel 4 of the liquid crystal display element 1 when ON, a region 9 in which the liquid crystal 6 is oriented upward is formed in the vicinity of the center due to the effect of the above-described orientation treatment. The The region 9 in which the liquid crystal 6 is aligned by the effect of the alignment process when the liquid crystal is turned on is a region in which the liquid crystal 6 is inclined in the pretilt angle forming direction by applying a voltage between the common electrode 2 and the segment electrode 3 in FIGS. . When the pixel 4 of the liquid crystal display element 1 is turned on, the alignment state of the liquid crystal 6 becomes a normal region indicating a desired state.

  On the other hand, as described with reference to the cross-sectional view in the left-right direction in FIG. 2, at the left and right ends of the pixel 4, the liquid crystal 6 is aligned in the left-right direction due to the influence of the edge of the segment electrode 3. To come. That is, in the vicinity of the left and right end portions of the pixel 4, alignment disorder occurs compared to the normal region 9 described above, and the alignment direction of the liquid crystal 6 is about 0 ° to 45 °, and larger, 45 °. Abnormal regions 10a and 10b which are shifted to a size of about ~ 90 ° are formed. The left and right abnormal regions 10a and 10b of the formed pixel are regions where the transmittance decreases and changes again when ON, and there is a concern that the display quality of the liquid crystal display element 1 may be decreased.

  Further, as described with reference to the vertical sectional view of FIG. 3, in the vicinity of the lower end portion of the pixel 4, the liquid crystal 6 is moved downward in FIG. 4 due to the influence of the edge of the common electrode 2 when ON. The orientation changes toward. That is, due to the effect of the alignment process described above, the direction of the alignment change is 180 ° different from that of the normal region 9 in which the liquid crystal 6 changes in the upward direction in FIG. Therefore, at the lower end portion of the pixel 4, a larger alignment disorder occurs than in the normal region 9 described above, and an abnormal region 10 c is formed. In the abnormal region 10c, a domain is generated in a portion where the direction of orientation change at ON is 180 ° different from that in the normal region 9. This domain is different in shape for each pixel 4 of the liquid crystal display element 1 and is not uniform, and is observed as rough display unevenness in the liquid crystal display element 1. As a result, the domain of the pixel 4 causes the display quality of the liquid crystal display element 1 to be significantly reduced.

  Conventionally, a method for improving the domain problem has been proposed.

  For example, Japanese Patent Application Laid-Open No. 2008-164983 proposes that slits are arranged in the line-to-line portions of the electrodes, and the alignment disorder due to the oblique electric field is reduced by the slits to make the liquid crystal alignment more uniform. . However, in this method, it is necessary to accurately arrange the slits at the designed positions in the electrodes, and it is necessary to bond the substrates having the electrodes with high accuracy. This is because if the bonding is shifted, an unintended oblique electric field is generated due to the shift between the electrodes sandwiching the liquid crystal layer. Further, the slit width needs to be large to some extent, and there is a concern that the aperture ratio of the pixel is lowered and the luminance of the liquid crystal display element is lowered.

  Japanese Patent Application Laid-Open No. 2010-224233 discloses that a triangular notch is arranged at an edge portion of an electrode, a black cross (domain) caused by an oblique electric field is fixed, and a uniform shape is obtained between pixels. A method for eliminating display non-uniformity has been proposed. However, in this method, it is necessary to set the length of the slope of the triangular cut to 50 μm or more, preferably 70 μm or more, and to set the straight line portion between the triangular cuts to 70 μm or less, preferably 40 μm or less. Further, two or more triangular incisions are required, and the structure in which such large incisions are provided in the pixel electrodes with a large arrangement interval is not suitable for forming a high-definition display, and the aperture ratio of the pixels Will be greatly reduced.

Therefore, based on the above examination results, the present inventor has studied the reduction of the domain problem of the VA liquid crystal display element capable of full dot display, and has reached the present invention. That is, according to the present invention, in a liquid crystal display element of a VA type having an electrode structure capable of full dot display, an opening of a small piece serving as a hollow portion is formed in an electrode in a region where alignment disorder is feared in a pixel. It is assumed that display unevenness or the like due to orientation disturbance is difficult to detect.
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

Embodiment 1. FIG.
The liquid crystal display element of the first embodiment of the present invention is a VA liquid crystal display element, which is a full-dot display type liquid crystal display element.

  FIG. 5 is a cross-sectional view schematically illustrating the configuration of the liquid crystal display element according to the first embodiment of the present invention.

  As shown in FIG. 5, the liquid crystal display element 101 according to the first embodiment of the present invention is opposed to the transparent first substrate 102 disposed on the front side, which is the viewer's side, and the first substrate 102. The liquid crystal panel 105 is formed by sandwiching the liquid crystal layer 104 between the transparent second substrate 103 disposed on the back side opposite to the observer.

  The liquid crystal layer 104 of the liquid crystal panel 105 can be formed using a nematic liquid crystal having a negative dielectric anisotropy (Δε). A common electrode 106 which is a patterned first electrode made of a transparent conductive material such as ITO is provided on the surface of the first substrate 102 on the liquid crystal layer 104 side. Similarly, a segment electrode 107, which is a patterned second electrode, made of a transparent conductive material such as ITO is provided on the surface of the second substrate 103 on the liquid crystal layer 104 side. The structures of the common electrode 106 and the segment electrode 107 will be described in detail later.

  A liquid crystal (not shown) of the liquid crystal layer 104 is disposed between the common electrode 106 and the liquid crystal layer 104 on the first substrate 102 of the liquid crystal panel 105 and between the segment electrode 107 and the liquid crystal layer 104 on the second substrate 103. A liquid crystal alignment film (not shown) that realizes a uniform vertical alignment (initial alignment). The liquid crystal alignment film on the common electrode 106 and the liquid crystal alignment film on the segment electrode 107 are each subjected to an alignment process so that the directions of the alignment processes are opposite to each other as shown in FIG. ing. Note that the alignment treatment of the liquid crystal alignment film is preferably performed by rubbing treatment.

  The liquid crystal display element 101 has an F polarizing plate 108 disposed on the front side of the first substrate 102 of the liquid crystal panel 105 and an R polarizing plate 109 disposed on the back side of the second substrate 103.

  Further, as shown in FIG. 5, the liquid crystal display element 101 has a backlight 110 disposed on the back side of the liquid crystal panel 105 and further on the back side of the R polarizing plate 109.

  FIG. 6 is a diagram for explaining the relationship between the direction of the alignment treatment of the liquid crystal alignment film and the absorption axis of the polarizing plate in the liquid crystal display element of the first embodiment of the present invention.

  The liquid crystal display element 101 uses a pair of polarizing plates of an F polarizing plate 108 and an R polarizing plate 109, sandwiches the liquid crystal layer 104 (not shown in FIG. 6) of the liquid crystal panel 105, and absorbs each other's absorption axis. Preferably, 117 and 118 are arranged so as to form an angle of 85 ° to 95 ° so as to form a crossed Nicols arrangement orthogonally.

  The liquid crystal panel 105 of the liquid crystal display element 101 is in a plan view, and the orientation direction of the liquid crystal alignment film on the common electrode 106 (not shown in FIG. 6) is the long side of the liquid crystal panel 105. The direction is from the top to the bottom so as to be perpendicular to the direction. In FIG. 6, the orientation processing direction on the viewing side is indicated by a solid arrow. Further, the direction of the alignment treatment of the liquid crystal alignment film on the segment electrode 107 (not shown in FIG. 6) is a direction from the bottom to the top so as to be perpendicular to the long side direction of the liquid crystal panel 105. . In FIG. 6, the direction of the orientation process on the non-viewing side is indicated by a dashed arrow. By setting the direction of the alignment treatment of each liquid crystal alignment film in this way, as described above, the liquid crystal alignment film on the common electrode 106 and the liquid crystal alignment film on the segment electrode 107 are aligned with each other. The reverse direction.

  The arrangement of the F polarizing plate 108 and the R polarizing plate 109 of the liquid crystal display element 101 is a crossed Nicols arrangement. That is, assuming that the long side direction of the liquid crystal display panel 105 is the reference axis and the counterclockwise angle from the reference axis when viewed from the viewing side to the absorption axis 117 of the F polarizing plate 108 is θ1, θ1 = 45 °. When the counterclockwise angle to the absorption axis 118 of the R polarizing plate 109 is θ2, θ2 is set to 135 °. By arranging the F polarizing plate 108 and the R polarizing plate 109 as described above, the absorption axes 117 and 118 are orthogonal to each other to form a crossed Nicol arrangement, and the alignment treatment direction of each liquid crystal alignment film of the liquid crystal panel 105 An angle of 45 ° is formed between the two. As a result, the liquid crystal display element 101 can change the orientation in which the liquid crystal of the liquid crystal layer 104 is tilted in the pretilt angle formation direction by applying a voltage between the common electrode 106 and the segment electrode 107, thereby forming a bright bright display. it can. Although the absorption axes 117 and 118 of the F polarizing plate 108 and the R polarizing plate 109 are orthogonal to each other here, their polarizing axes may be orthogonal to each other.

The liquid crystal display element 101 enables full dot display. Therefore, the common electrode 106 and the segment electrode 107 of the liquid crystal panel 105 described above have an electrode structure suitable for full dot display.
Next, the electrode structure and effects of the liquid crystal display element 101 according to the first embodiment of the present invention will be described in more detail.

  FIG. 7 is a plan view schematically showing a part of the electrode structure of the liquid crystal display element according to the first embodiment of the present invention.

  As described above, the full-dot display type VA liquid crystal display element 101 includes a first substrate (not shown in FIG. 7) disposed on the front side which is the viewer side, and the first substrate. And a second substrate (not shown) disposed on the back side. On the surface of the first substrate on the second substrate side, a plurality of common electrodes 106 that are a plurality of first electrodes formed in a strip shape extending in the lateral direction, which is the first direction, are provided. In addition, on the surface of the second substrate on the first substrate side, a segment electrode that is a plurality of second electrodes formed in a strip shape extending in the vertical direction, which is the second direction orthogonal to the common electrode 106 107 is provided. The liquid crystal display element 101 is sandwiched between the common electrode 106 forming surface of the first substrate and the segment electrode 107 forming surface of the second substrate which face each other, and forms a pretilt angle in a predetermined direction between these electrodes. The liquid crystal (not shown in FIG. 7) has a liquid crystal layer (not shown in FIG. 7) in which the liquid crystal is aligned substantially vertically.

  In the liquid crystal display element 101, as described above, a vertical alignment liquid crystal alignment film (not shown) is disposed between the common electrode 106 on the first substrate and the liquid crystal layer. The liquid crystal alignment film is provided in the liquid crystal display element 101 of FIG. 7 and is subjected to alignment processing from the upper side to the lower side of the drawing as described above. Similarly, in the liquid crystal display element 101, a vertical alignment liquid crystal alignment film (not shown) is disposed between the segment electrode 107 on the second substrate and the liquid crystal layer, and the liquid crystal alignment film is located upward from below in the figure. An orientation treatment is applied toward the surface. By providing such a liquid crystal alignment film, the liquid crystal display element 101 of FIG. 7 realizes a structure in which the liquid crystal is substantially vertically aligned by forming a pretilt angle in a direction parallel to the vertical direction of the desired figure.

  The pretilt angle of the liquid crystal is preferably 85 ° to 89.9 °. When the angle is less than 85 °, a dark display when an OFF voltage is applied or when no voltage is applied (hereinafter simply referred to as OFF time) becomes bright and the contrast ratio decreases. On the other hand, when the angle is larger than 89.9 °, particularly when the angle is 90 °, it becomes difficult to control the direction in which the liquid crystal is tilted when the switch is turned on.

  In FIG. 7, only the direction of the alignment treatment of the liquid crystal alignment film is indicated by an arrow, the solid line arrow pointing downward indicates the direction of the alignment treatment of the liquid crystal alignment film on the common electrode 106 side, and the broken line pointing upward An arrow indicates the direction of the alignment treatment of the liquid crystal alignment film on the segment electrode 107 side.

  In the liquid crystal display element 101, a plurality of common electrodes 106 having a predetermined line width L11 are arranged in stripes so as to be separated from each other with a predetermined line distance L12. Similarly, a plurality of segment electrodes 107 having a predetermined line width L13 are arranged in stripes so as to be adjacent to each other with a predetermined line distance L14. As a result, in the liquid crystal display element 101, the overlapping portion of the common electrode 106 and the segment electrode 107 constitutes one pixel 114 in a state in plan view as shown in FIG. The liquid crystal display element 101 can perform full dot display using the pixels 114 arranged in a matrix form of upper, lower, left, and right, and can display a desired high-definition image.

  At this time, each pixel 114 of the liquid crystal display element 101 is formed as an overlapping region of the common electrode 106 having two edges and the segment electrode 107 having two edges, as shown in FIG. Therefore, the pixel 114 is affected by the edge of the common electrode 106 and the edge of the segment electrode 107 when performing bright display when ON. That is, in the pixel 114, the alignment of the liquid crystal when ON is affected by an oblique electric field from the edges of the common electrode 106 and the segment electrode 107. In each pixel 114 of the liquid crystal display element 101, the influence of the oblique electric field is the same as that of the VA liquid crystal display element 1 that performs full-dot display described with reference to FIGS. As a result, the pixel 114 of the liquid crystal display element 101 exhibits the same liquid crystal alignment state as the pixel 4 described with reference to FIG.

  FIG. 8 is a plan view schematically showing the alignment state of the liquid crystal of the pixel of the liquid crystal display element according to the first embodiment of the present invention.

  That is, in the pixel 114 of the liquid crystal display element 101, the orientation direction of the liquid crystal 116 in the liquid crystal layer (not shown in FIG. 8) is not uniform due to the above-described influence of the oblique electric field at the time of ON. And may include various orientation states. In FIG. 8, as in FIG. 4, arrows are used to schematically show the liquid crystal 116 and its tilt direction.

  In FIG. 8, only the direction of alignment treatment of the liquid crystal alignment film (not shown) of the pixel 114 is indicated by an arrow, and the solid line arrow pointing downward is on the common electrode 106 (not shown in FIG. 8) side. The direction of the alignment treatment of the liquid crystal alignment film is shown, and the broken arrow pointing upward indicates the direction of the alignment treatment of the liquid crystal alignment film on the segment electrode 107 (not shown in FIG. 8) side.

  As shown in FIG. 8, in the pixel 114 of the liquid crystal display element 101 when ON, a region 119 in which the liquid crystal 116 is oriented upward in the figure is formed in the vicinity of the center due to the effect of the alignment treatment described above. A region 119 in which the liquid crystal 116 is aligned by the effect of the alignment treatment when the liquid crystal is turned on is a region in which the liquid crystal 116 is inclined in the pretilt angle forming direction by applying a voltage between the common electrode 106 and the segment electrode 107 in FIG. The normal state where the alignment state of the liquid crystal desired in the pixel 114 of the display element 101 is normal is obtained.

  On the other hand, the edges of the left and right ends of the pixel 114 are constituted by the edges of the segment electrode 107 parallel to the direction in which the pretilt angle of the liquid crystal 116 is formed. receive. As a result, the liquid crystal 116 is aligned in the left-right direction in the vicinity of the left and right edges of the pixel 114 parallel to the pretilt angle forming direction. In other words, alignment disturbance occurs in the left and right peripheral portions of the pixel 114 as compared with the normal region described above, and the alignment direction of the liquid crystal 116 is larger than 0 ° and about 45 °, and further larger than 45 ° and 90 °. Abnormal regions 120a and 120b that are shifted to a size of about ° are formed. The left and right abnormal regions 120a and 120b of the formed pixel 114 are regions that cause a large fluctuation such as a decrease or increase in transmittance when ON, and there is a concern that the display quality of the liquid crystal display element 101 may be deteriorated.

  Further, the edge of the lower end portion of the pixel 114 is constituted by the edge of the common electrode 106 perpendicular to the pretilt angle forming direction, and is affected by an oblique electric field from the edge of the common electrode 106 when ON. As a result, in the vicinity of the edge below the pixel 114 and perpendicular to the pretilt angle formation direction, the orientation of the liquid crystal 116 changes downward in the drawing. That is, in the region near the edge in the direction opposite to the direction in which the liquid crystal in the normal region inclines, compared to the normal region in which the liquid crystal 116 changes in the orientation upward in the figure due to the effect of the alignment treatment described above. , The direction of the orientation change of the liquid crystal 116 is 180 ° different. Therefore, in the vicinity of the lower edge of the pixel 114, a larger alignment disorder occurs than in the normal region described above, and an abnormal region 120c is formed. In the abnormal region 120c, when ON, a domain is generated in a portion where the direction of orientation change is 180 ° different from that of the normal region. This domain differs in shape from pixel 114 to pixel 114 of the liquid crystal display element 101 and is not uniform. When this domain is visible in the liquid crystal display element 101, there is a concern that it is observed as rough display unevenness. In that case, the domain of the pixel 114 causes the display quality of the liquid crystal display element 101 to be significantly lowered.

  For this reason, in the liquid crystal display element 101 according to the first embodiment of the present invention, the common electrode 106 and / or the segment electrode 107 are cut out in a region in the pixel 114 where there is a fear of alignment disorder, such as the abnormal regions 120a to 120c. An opening of a small piece serving as a part is arranged so that display unevenness due to orientation disorder is hardly detected.

  FIG. 9 is a diagram schematically showing an electrode structure of a pixel of the liquid crystal display element according to the first embodiment of the present invention.

  As shown in FIG. 9, in the liquid crystal display element 101 according to the first embodiment of the present invention, a small-sized opening 121 which is a portion where an electrode is not formed is arranged in a pixel 114. The opening 121 can be formed as a hollowed portion in the electrode portion constituting the pixel 114. The opening 121 can be formed in the common electrode 106 constituting the pixel 114, and can be formed in the segment electrode 107. Further, the opening 121 can be formed in both the common electrode 106 and the segment electrode 107.

  In the liquid crystal display element 101 according to the first embodiment of the present invention, as the arrangement region of the opening 121 in the pixel 114, as shown in FIG. 9, the alignment treatment direction, that is, the pretilt angle forming direction of the liquid crystal (not shown). Of the edges positioned in the direction orthogonal to the region, it is preferable to use a region in the vicinity of the lower edge in the drawing. The vicinity of the lower edge of the pixel 114 is actually the vicinity of the edge of the common electrode 106 constituting the pixel 114. The opening 121 is provided in the common electrode 106 and / or the segment electrode 107 near the edge perpendicular to the liquid crystal pretilt angle forming direction on the lower side of the pixel 114. A region near the lower edge of the pixel 114 substantially coincides with the position of the abnormal region 120c shown in FIG. That is, in the liquid crystal display element 101, the opening 121 of the pixel 114 is an edge that is orthogonal to the liquid crystal pretilt angle forming direction and is in the vicinity of the edge in the direction opposite to the direction in which the liquid crystal in the normal region is inclined. Are provided on the common electrode 106 and / or the segment electrode 107 in the abnormal region 120c.

  In the liquid crystal display element 101 according to the first embodiment of the present invention, the opening 121 that is a cut-out portion of the electrode of the pixel 114 does not prevent the liquid crystal from being tilted by voltage application between the common electrode 106 and the segment electrode 107. The size is preferred.

  More specifically, the opening 121 is preferably set in a range of 3 μm to 6 μm in width. This is because the effect of lowering the transmittance of the pixel 114, which will be described later, is reduced when the thickness is less than 3 μm. Further, when the length is longer than 6 μm, the influence of the oblique electric field generated by each opening 121 becomes large, and liquid crystal alignment disorder caused by the opening 121 is likely to occur. In the liquid crystal display element 101 of the first embodiment of the present invention, a small opening 121 that does not adversely affect the alignment state of the liquid crystal is desirable.

  In the liquid crystal display element 101 according to the first embodiment of the present invention, the shape of the opening 121 is preferably rectangular or circular. The shape of the opening 121 may be a polygon or an ellipse, but is preferably a regular polygon or a circle that is equal to or greater than a quadrangle, and more preferably a square. The openings 121 only need to have a width in the range of 3 μm to 6 μm, and may have different sizes or different shapes.

And in the liquid crystal display element 101 of 1st Embodiment of this invention, the arrangement | positioning space | interval between the adjacent opening parts 121 is in the range of 3 micrometers-20 micrometers in the direction of the alignment process used as the formation direction of the pretilt angle mentioned above. The thickness is preferably set in the range of 4 μm to 20 μm in the direction orthogonal to the alignment treatment. When the arrangement interval of the adjacent openings 121 is less than 3 μm in the alignment treatment direction or less than 4 μm in the direction orthogonal to the alignment treatment, the influence of the oblique electric field generated by each opening 121 becomes large, and the openings 121 This is because liquid crystal orientation disorder is likely to occur due to the above. Further, if the arrangement interval of the openings 121 is longer than 20 μm in the alignment process direction or the direction orthogonal to the alignment process, the effect of reducing the transmittance of the pixel 114 described later is reduced.
Each of the plurality of openings 121 need not be regularly arranged, and may be irregularly arranged within the above-described arrangement interval.

  As described above, the liquid crystal display element 101 according to the first embodiment of the present invention has the common electrode 106 and / or the segment electrode 107 in the vicinity of the lower edge of the pixel 114 so as not to adversely affect the alignment state of the liquid crystal. A small piece opening 121 formed by hollowing out is disposed. In the pixel 114, a portion where the opening 121 is formed is a region that does not form a bright display when turned on and maintains a dark display when turned off. Therefore, the liquid crystal display element 101 can reduce the brightness in the vicinity of the lower end of each pixel 114 when the liquid crystal display element 101 is turned on. Therefore, even if a liquid crystal alignment disorder or a domain occurs in a region near the lower end where the opening 121 is arranged, it is difficult to observe luminance changes and rough display unevenness due to them, and the display quality is improved. The decrease can be suppressed.

Embodiment 2. FIG.
The liquid crystal display element according to the second embodiment of the present invention is a VA liquid crystal display element, which is a full dot display type liquid crystal display element.

  The liquid crystal display element of the second embodiment of the present invention is characterized by the arrangement structure of the openings provided in each pixel, and the other structure is the liquid crystal display element 101 of the first embodiment of the present invention described above. Has the same structure.

  FIG. 10 is a cross-sectional view schematically illustrating the configuration of the liquid crystal display element according to the second embodiment of the present invention.

  That is, as shown in FIG. 10, the liquid crystal display element 201 of the second embodiment includes a backlight 110, an R polarizing plate 109, a second substrate 103, a segment electrode 207, a liquid crystal layer 104, and a common electrode on the rearmost side. 206, the first substrate 102, and the F polarizing plate 108 on the forefront side are arranged in this order. Note that the second substrate 103, the segment electrode 207, the liquid crystal layer 104, the common electrode 206, and the first substrate 102 constitute a liquid crystal panel 205 in the same manner as the liquid crystal display element 101 of the first embodiment described above.

  Therefore, the liquid crystal display element 201 of the second embodiment will be described focusing on the arrangement structure of the openings of the pixel electrodes, which is different from the liquid crystal display element 101 of the first embodiment, and the other basic configurations are common. Constituent elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 11 is a plan view schematically showing a part of the electrode structure of the liquid crystal display element according to the second embodiment of the present invention.

  The VA-type liquid crystal display element 201 of the full-dot display system is a strip that is arranged on the front side that is the viewer side and extends in the horizontal direction that is the first direction, like the liquid crystal display element 101 of the first embodiment described above. A first substrate 102 (not shown in FIG. 11) having a common electrode 206 that is a plurality of first electrodes formed in a shape, and a common electrode 206 disposed on the back side of the first substrate 102. And a second substrate 103 (not shown in FIG. 11) having a segment electrode 207 which is a plurality of second electrodes formed in a strip shape extending in the up-down direction which is a second direction orthogonal to each other. The liquid crystal display element 201 is sandwiched between the common electrode 206 formation surface of the first substrate 102 and the segment electrode 207 formation surface of the second substrate 103, and forms a pretilt angle in a predetermined direction between the electrodes. (Not shown in FIG. 11) includes a liquid crystal layer 104 (not shown in FIG. 11) that is substantially vertically aligned.

  That is, the liquid crystal display element 201 has a vertical alignment liquid crystal alignment film (not shown) between the common electrode 206 and the liquid crystal layer 104 on the first substrate, similarly to the liquid crystal display element 101 of the first embodiment described above. ). Although the liquid crystal alignment film is not shown, the alignment process is performed from the upper side to the lower side of the drawing in the state provided in the liquid crystal display element 201 of FIG. 11 as in the first embodiment of FIG. ing. Similarly, in the liquid crystal display element 201, a vertical alignment liquid crystal alignment film (not shown) is disposed between the segment electrode 207 and the liquid crystal layer 104 on the second substrate, and the above-described first embodiment of FIG. Similarly to the above, an orientation process is performed from the bottom to the top of the figure. The liquid crystal display element 201 in FIG. 11 is provided with a liquid crystal alignment film subjected to such an alignment treatment, thereby forming a pretilt angle in a direction parallel to the vertical direction as in the first embodiment in FIG. A vertically aligned structure is realized.

At this time, the preferable setting range of the pretilt angle of the liquid crystal is the same as that of the liquid crystal display element 101 of the first embodiment described above.
In FIG. 11, only the direction of the alignment treatment of the liquid crystal alignment film is indicated by an arrow, the solid line arrow pointing downward indicates the direction of the alignment treatment of the liquid crystal alignment film on the common electrode 206 side, and the broken line pointing upward An arrow indicates the direction of the alignment treatment of the liquid crystal alignment film on the segment electrode 207 side.

  In the liquid crystal display element 201, a plurality of common electrodes 206 having a predetermined line width L21 are arranged in stripes so as to be separated from each other with a predetermined line distance L22. Similarly, a plurality of segment electrodes 207 having a predetermined line width L23 are arranged in stripes so as to be adjacent to each other with a predetermined inter-line distance L24. As a result, in the liquid crystal display element 201 in a plan view as shown in FIG. 11, the overlapping portions of the common electrode 206 and the segment electrode 207 each constitute one pixel 214. The liquid crystal display element 201 can perform full-dot display using the pixels 214 arranged in a matrix form of upper, lower, left, and right, and can display a desired high-definition image.

  At this time, each pixel 214 of the liquid crystal display element 201 is an overlapping portion of the common electrode 206 and the segment electrode 207, and an area surrounded by the edge of the common electrode 206 and the edge of the segment electrode 207 as shown in FIG. Formed as. Therefore, the pixel 214 is affected by the edge of the common electrode 206 and the edge of the segment electrode 207 when performing bright display when ON. That is, the orientation of the liquid crystal of the pixel 214 at the time of ON is affected by an oblique electric field from the edges of the common electrode 206 and the segment electrode 207. In each pixel 214 of the liquid crystal display element 201, the influence of the oblique electric field is the same as that of the VA liquid crystal display element 1 that performs full-dot display described with reference to FIGS. As a result, the pixel 214 of the liquid crystal display element 201 shows the same liquid crystal alignment state as the pixel 4 of FIG.

  That is, similar to the liquid crystal display element 101 of the first embodiment described above, the liquid crystal display element 201 has an alignment state of the liquid crystal when the pixel 214 is turned on in the vicinity of the edges parallel to the liquid crystal pretilt angle forming direction. An abnormal region is formed. As in the liquid crystal display element 101, this abnormal region has a liquid crystal alignment direction of 0 ° to 45 °, and further 45 °, compared to a normal region in which the liquid crystal is inclined in the pretilt angle forming direction due to the effect of the alignment treatment. The region is shifted to about 90 °. The left and right abnormal regions are regions that cause large fluctuations such as a decrease or increase in transmittance at the time of ON, and there is a concern that the display quality of the liquid crystal display element 201 may be deteriorated.

  Further, near the edge perpendicular to the liquid crystal pretilt angle forming direction at the lower end of the pixel 214 of the liquid crystal display element 201, the same as the liquid crystal display element 101 of the first embodiment described above when ON. An abnormal region of the alignment state of the liquid crystal is formed. This abnormal region, like the liquid crystal display element 101, has a large alignment disorder when the ON state is ON, in which the direction of change in the alignment of the liquid crystal is 180 ° different from the normal region in which the liquid crystal of the pixel 214 is aligned in the pretilt angle forming direction. This is the area to be generated.

  In the abnormal region in the vicinity of the lower edge of the pixel 214, when ON, a domain is generated in a portion where the direction of orientation change is 180 ° different from that of the normal region. This domain differs in shape for each pixel 214 of the liquid crystal display element 201 and is not uniform. When this domain is visible in the liquid crystal display element 201, there is a concern that it is observed as rough display unevenness. In that case, the domain causes the display quality of the liquid crystal display element 201 to be significantly lowered.

  For this reason, in the liquid crystal display element 201 according to the second embodiment of the present invention, a small opening is disposed in the pixel 214. That is, in the vicinity of the left and right edges of the pixel 214 parallel to the liquid crystal pretilt formation direction and the lower edge perpendicular to the liquid crystal pretilt formation direction, the occurrence of each abnormal region described above is a concern. An opening of a small piece that is a cut-out portion is formed in the electrode portion. The liquid crystal display element 201 is difficult to detect display unevenness or the like due to alignment disorder due to the arrangement of such openings in the pixel 214.

  FIG. 12 is a diagram schematically showing an electrode structure of a pixel of the liquid crystal display element according to the second embodiment of the present invention.

  As shown in FIG. 12, in the liquid crystal display element 201 according to the second embodiment of the present invention, a small piece opening 221 that is a portion where an electrode is not formed is arranged in a pixel 214. The opening 221 can be formed as a hollowed portion in the electrode portion constituting the pixel 214. The opening 221 can be formed in the common electrode 206 constituting the pixel 214, can be formed in the segment electrode 207, or can be formed in both of them.

  In the liquid crystal display element 201 according to the second embodiment of the present invention, as the arrangement region of the opening 221 in the pixel 214, as shown in FIG. 12, the alignment processing direction, that is, the pretilt angle forming direction of the liquid crystal (not shown). Of the edges located in the direction orthogonal to the region, it is preferable to set the region near the lower edge in the drawing and the region near the left and right edges parallel to the liquid crystal pretilt angle forming direction.

In the liquid crystal display element 201, the vicinity of the lower edge of the pixel 214 is actually the vicinity of the edge of the common electrode 206 constituting the pixel 214. In that case, the opening 221 is provided in the common electrode 206 and / or the segment electrode 207 near the edge perpendicular to the liquid crystal pretilt angle formation direction on the lower side of the pixel 214.
Further, the vicinity of the left and right edges of the pixel 214 is actually near the edge of the segment electrode 207 constituting the pixel 214. In that case, the opening 221 is provided in the common electrode 206 and / or the segment electrode 207 in the vicinity of the edge located in the direction parallel to the liquid crystal pretilt angle forming direction on the left and right of the pixel 214.

The vicinity of the edge on the lower side of the pixel 214 is substantially the same as the formation position of the abnormal region in which the occurrence of the domain described above is concerned, like the pixel 114 of the liquid crystal display element 101 of the first embodiment shown in FIG. To do.
Further, in the vicinity of the left and right edges of the pixel 214, as in the pixel 114 of the liquid crystal display element 101 of the first embodiment shown in FIG. 8, the liquid crystal alignment direction is shifted from 0 ° to 90 ° from the normal region. Almost coincides with the formation position of the abnormal region.

  Therefore, in the liquid crystal display element 201, the opening 221 of the pixel 214 is in the vicinity of an edge in a direction opposite to the above-described direction in which the liquid crystal in the normal region is tilted out of the edges perpendicular to the liquid crystal pretilt angle forming direction. Located in the abnormal area. Further, in the liquid crystal display element 201, the liquid crystal display element 201 is disposed in an abnormal region in the vicinity of an edge parallel to the liquid crystal pretilt angle forming direction. More specifically, it is provided on the common electrode 206 and / or the segment electrode 207 in those abnormal regions.

  In the liquid crystal display element 201 of the second embodiment of the present invention, the opening 221 of the pixel 214 has a size, a shape, an arrangement interval, etc., and the pixel 114 of the liquid crystal display element 101 of the first embodiment of FIG. The opening 121 is preferably the same.

  As described above, in the liquid crystal display element 201 according to the second embodiment of the present invention, the small-sized opening 221 that does not adversely affect the alignment state of the liquid crystal is provided in the vicinity of the lower edge of the pixel 214. Similarly, small openings 221 that do not adversely affect the alignment state of the liquid crystal are provided near the left and right edges of the pixel 214.

  In the pixel 214, a portion where the opening 221 is formed is a region that does not form a bright display when turned on and maintains a dark display when turned off. Therefore, the liquid crystal display element 201 can reduce the brightness in the vicinity of the lower side end of each pixel 214 and in the vicinity of the left and right end portions of each pixel 214 when the aperture 221 is arranged. Therefore, even if liquid crystal alignment disorder or domains occur in the region near the lower end and the left and right ends where the opening 221 is arranged, luminance change and rough display unevenness due to them are observed. Can be difficult. And the liquid crystal display element 201 can suppress the deterioration of display quality.

  Hereinafter, embodiments of the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples.

Example 1.
The liquid crystal display element of the first embodiment of the present invention is a full-dot display type VA liquid crystal display element, and is an example of the liquid crystal display element 101 of the first embodiment of the present invention shown in FIGS. is there. That is, the liquid crystal display element of the first embodiment has the electrode structure shown in FIG. In the liquid crystal display element of the first embodiment, there is a concern about the alignment disorder at the time of ON near the end of the pixel located on the side opposite to the side where the liquid crystal is tilted by the effect of the alignment process of the liquid crystal alignment film. In the region to be formed, an opening of a small piece serving as a hollow portion is arranged in the electrode so that display unevenness or the like due to orientation disorder is hardly detected.

  In order to manufacture the liquid crystal display element of the first embodiment of the present invention, a pair of glass substrates with an ITO film was prepared. One of the prepared glass substrates was used as a first substrate with an ITO film, and patterning was performed by a known method. And the common side board | substrate which has the some common electrode formed in the strip shape extended in the horizontal direction similar to what was shown in FIG. 7 was manufactured. The width (L11) of each common electrode was 350 μm, and the distance between lines (L12) was 10 μm.

  Subsequently, the other side of the glass substrate was used as a second substrate with an ITO film and patterned by a known method to produce a segment side substrate having a plurality of segment electrodes formed in a strip shape extending in the vertical direction. The width (L13) of each segment electrode was 350 μm, and the distance between lines (L14) was 10 μm. At this time, in order to realize the electrode structure of the pixel similar to that shown in FIG. 9, the electrode is cut out in a predetermined portion of the segment electrode with the same size, shape, and arrangement interval as shown in FIG. A partial opening was formed. More specifically, as a small-sized opening that does not adversely affect the alignment state of the liquid crystal, a plurality of square-shaped openings each having substantially the same shape and size, each having a side length of 5 μm, are formed on the segment electrode. It was formed in a predetermined region of the pixel formation portion. At this time, in the plurality of openings of the segment electrode, the arrangement interval between the openings adjacent in the direction of the alignment treatment described later is 4 μm, and the interval between the openings adjacent in the direction orthogonal to the alignment treatment direction is 5 μm.

Next, a vertical liquid crystal alignment film is formed on the electrode forming surfaces of both the common side substrate and the segment side substrate, and anti-parallel (anti-parallel) rubbing treatment is performed on both substrates, and the rubbing treated common Side substrates and segment side substrates were manufactured. Then, a VA type liquid crystal panel of a full dot display system was manufactured by sandwiching the liquid crystal using the common side substrate and the segment side substrate that had been subjected to the rubbing treatment. A liquid crystal having a dielectric anisotropy (Δε) of −2.7 was used. The retardation (Δn · d) of the liquid crystal panel was set to 810 nm. The pretilt angle of the liquid crystal of the liquid crystal panel was 89.8 °.
Each pixel of the manufactured liquid crystal panel has a square shape with one side of 350 μm, and the distance between the lines is 10 μm.

  Next, the manufactured liquid crystal panel was sandwiched between a pair of polarizing plates of an F polarizing plate on the front side and an R polarizing plate on the back side to manufacture a VA mode liquid crystal display element. As the F polarizing plate, VHC-128UL2SZ-K1 manufactured by Polatechno Co., Ltd. is used, and as the R polarizing plate, 045R660N2-VH39L2S (Re = 45 nm, polarizing plate with optical compensation film of Rth = 660 nm) manufactured by Polatechno Co., Ltd. is used. Using.

  At this time, when the long side direction of the rectangular liquid crystal panel is the reference axis, and the counterclockwise angle from the reference axis when viewed from the front side that is the viewing side to the absorption axis of the F polarizing plate is θ1, When θ1 = 45 ° and when the counterclockwise angle to the absorption axis of the R polarizing plate is θ2, θ2 = 135 °. With such a setting, an angle of 45 ° is formed with respect to the rubbing process direction of the common substrate and the segment substrate described above. Although the absorption axes of the F polarizing plate and the R polarizing plate are orthogonal to each other, the polarization axes may be orthogonal.

When the liquid crystal display element according to the first embodiment manufactured as described above was used and was driven at a duty ratio of 1/48 for full dot display, good visibility was obtained. That is, a good black display was obtained when turned off, and a bright white display was obtained when turned on.
Furthermore, as compared with the comparative example described later, the liquid crystal display element of the first embodiment can reduce the brightness of each pixel near the end where there is a concern about the occurrence of the domain by about 30%. Display unevenness became difficult to observe, and deterioration of display quality could be suppressed.

Comparative example.
The liquid crystal display element of the comparative example of the present invention is a full-dot display type VA liquid crystal display element, which is an example of the liquid crystal display element 1 shown in FIGS. In other words, the liquid crystal display element of the comparative example has the electrode structure shown in FIG. 1 and no opening as in the first embodiment described above is formed in the pixel.

  In order to manufacture the liquid crystal display element of the comparative example, a pair of glass substrates with an ITO film was prepared. One of the prepared glass substrates was used as a first substrate with an ITO film, and patterning was performed by a known method. And the common side board | substrate which has the some common electrode formed in the strip shape extended in the horizontal direction similar to what was shown in FIG. 1 was manufactured. The width (L1) of each common electrode was 350 μm and the line-to-line distance (L2) was 10 μm.

  Subsequently, the other side of the glass substrate was used as a second substrate with an ITO film and patterned by a known method to produce a segment side substrate having a plurality of segment electrodes formed in a strip shape extending in the vertical direction. The width (L3) of each segment electrode was 350 μm, and the distance between lines (L4) was 10 μm.

Next, a vertical liquid crystal alignment film is formed on the electrode forming surfaces of both the common side substrate and the segment side substrate, and anti-parallel (anti-parallel) rubbing treatment is performed on both substrates, and the rubbing treated common Side substrates and segment side substrates were manufactured. Then, a VA type liquid crystal panel of a full dot display system was manufactured by sandwiching the liquid crystal using the common side substrate and the segment side substrate that had been subjected to the rubbing treatment. A liquid crystal having a dielectric anisotropy (Δε) of −2.7 was used. The retardation (Δn · d) of the liquid crystal panel was set to 810 nm. The pretilt angle of the liquid crystal of the liquid crystal panel was 89.8 °.
Each pixel of the manufactured liquid crystal panel has a square shape with one side of 350 μm, and the distance between the lines is 10 μm.

  Next, the manufactured liquid crystal panel was sandwiched between a pair of polarizing plates of an F polarizing plate on the front side and an R polarizing plate on the back side to manufacture a VA mode liquid crystal display element. As the F polarizing plate, VHC-128UL2SZ-K1 manufactured by Polatechno Co., Ltd. is used, and as the R polarizing plate, 045R660N2-VH39L2S (Re = 45 nm, polarizing plate with optical compensation film of Rth = 660 nm) manufactured by Polatechno Co., Ltd. is used. Using.

  At this time, when the long side direction of the rectangular liquid crystal panel is the reference axis, and the counterclockwise angle from the reference axis when viewed from the front side that is the viewing side to the absorption axis of the F polarizing plate is θ1, When θ1 = 45 ° and when the counterclockwise angle to the absorption axis of the R polarizing plate is θ2, θ2 = 135 °. With such a setting, an angle of 45 ° is formed with respect to the rubbing process direction of the common substrate and the segment substrate described above.

When the liquid crystal display element of the comparative example produced as described above was used and driven at a duty ratio of 1/48 to perform full dot display, good visibility was obtained. That is, a good black display was obtained when turned off, and a bright white display was obtained when turned on.
However, in the liquid crystal display element of the comparative example, rough display unevenness due to the domains generated in the pixels was observed, and the display quality was significantly reduced.

Example 2
The liquid crystal display element of the second embodiment of the present invention is a full-dot display type VA liquid crystal display element, and the liquid crystal display element 201 of the second embodiment of the present invention shown in FIGS. Become. That is, the liquid crystal display element of the second embodiment has the electrode structure shown in FIG. And the liquid crystal display element of 2nd Example is a small piece which becomes a hollow part in the electrode of the vicinity of the edge located on the opposite side to the side where a liquid crystal falls down by the effect of the alignment process of a liquid crystal aligning film of a pixel. Arrange the opening. In addition, even in a region where there is a concern about alignment disturbance at the time of ON in the vicinity of the end of the pixel that is parallel to the direction of alignment treatment of the liquid crystal alignment film, an opening of a small piece that becomes a hollow portion is formed on the electrode. Deploy. In this way, the liquid crystal display element of the second embodiment is arranged so that openings are formed in the vicinity of the three end portions of each pixel so that display unevenness due to orientation disorder is difficult to detect. Is done.

  In order to manufacture the liquid crystal display element of the second embodiment of the present invention, a pair of glass substrates with an ITO film was prepared. One of the prepared glass substrates was used as a first substrate with an ITO film, and patterning was performed by a known method. And the common side board | substrate which has the some common electrode formed in the strip shape extended in the horizontal direction similar to what was shown in FIG. 11 was manufactured. The width (L21) of each common electrode was 350 μm and the line-to-line distance (L22) was 10 μm.

  Subsequently, the other side of the glass substrate was used as a second substrate with an ITO film and patterned by a known method to produce a segment side substrate having a plurality of segment electrodes formed in a strip shape extending in the vertical direction. The width (L23) of each segment electrode was 350 μm, and the distance between lines (L24) was 10 μm. At this time, in order to realize the electrode structure of the pixel similar to that shown in FIG. 12, a predetermined portion of the segment electrode is cut out with the same size, shape, and arrangement interval as shown in FIG. A partial opening was formed. More specifically, as a small-sized opening that does not adversely affect the alignment state of the liquid crystal, a plurality of square-shaped openings each having substantially the same shape and size, each having a side length of 5 μm, are formed on the segment electrode. It was formed in a predetermined region of the pixel formation portion. At this time, in the plurality of openings of the segment electrode, the arrangement interval between the openings adjacent in the direction of the alignment treatment described later is 4 μm, and the interval between the openings adjacent in the direction orthogonal to the alignment treatment direction is 5 μm.

Next, a vertical liquid crystal alignment film is formed on the electrode forming surfaces of both the common side substrate and the segment side substrate, and anti-parallel (anti-parallel) rubbing treatment is performed on both substrates, and the rubbing treated common Side substrates and segment side substrates were manufactured. Then, a VA type liquid crystal panel of a full dot display system was manufactured by sandwiching the liquid crystal using the common side substrate and the segment side substrate that had been subjected to the rubbing treatment. A liquid crystal having a dielectric anisotropy (Δε) of −2.7 was used. The retardation (Δn · d) of the liquid crystal panel was set to 810 nm. The pretilt angle of the liquid crystal of the liquid crystal panel was 89.8 °.
Each pixel of the manufactured liquid crystal panel has a square shape with one side of 350 μm, and the distance between the lines is 10 μm.

  Next, the manufactured liquid crystal panel was sandwiched between a pair of polarizing plates of an F polarizing plate on the front side and an R polarizing plate on the back side to manufacture a VA mode liquid crystal display element. As the F polarizing plate, VHC-128UL2SZ-K1 manufactured by Polatechno Co., Ltd. is used, and as the R polarizing plate, 045R660N2-VH39L2S (Re = 45 nm, polarizing plate with optical compensation film of Rth = 660 nm) manufactured by Polatechno Co., Ltd. is used. Using.

  At this time, when the long side direction of the rectangular liquid crystal panel is the reference axis, and the counterclockwise angle from the reference axis when viewed from the front side that is the viewing side to the absorption axis of the F polarizing plate is θ1, When θ1 = 45 ° and when the counterclockwise angle to the absorption axis of the R polarizing plate is θ2, θ2 = 135 °. With such a setting, an angle of 45 ° is formed with respect to the rubbing process direction of the common substrate and the segment substrate described above. Although the absorption axes of the F polarizing plate and the R polarizing plate are orthogonal to each other, the polarization axes may be orthogonal.

When the liquid crystal display element according to the second embodiment manufactured as described above was used and was driven at a duty ratio of 1/48 for full dot display, good visibility was obtained. That is, a good black display was obtained when turned off, and a bright white display was obtained when turned on.
Furthermore, compared with the comparative example described above, the liquid crystal display element of the second example has brightness of each pixel near the three end portions where there is a concern about transmittance change due to domain generation or orientation disorder. It could be reduced by 30%. As a result, in the liquid crystal display element of the second example, it was difficult to observe a large change in transmittance due to alignment disorder and rough display unevenness due to domains, and a reduction in display quality could be suppressed.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

1, 101, 201 Liquid crystal display element 2, 106, 206 Common electrode 3, 107, 207 Segment electrode 4, 114, 214 Pixel 5, 104 Liquid crystal layer 6, 116 Liquid crystal 7, 8 Diagonal electric field 9, 119 Region 10a, 10b, 10c, 120a, 120b, 120c Abnormal region 102 First substrate 103 Second substrate 105, 205 Liquid crystal panel 108 F polarizing plate 109 R polarizing plate 110 Back light 117, 118 Absorption axis 121, 221 Opening

Claims (6)

A plurality of strip-shaped first electrodes extending in a first direction; a plurality of strip-shaped second electrodes extending in a second direction so as to be orthogonal to the first electrodes;
A liquid crystal layer that is sandwiched between the first electrode and the second electrode and forms a pretilt angle in a predetermined direction so that the liquid crystal is substantially vertically aligned;
The liquid crystal is tilted in the direction in which the pretilt angle is formed by applying a voltage between the first electrode and the second electrode in a pixel that is an overlapping portion of the first electrode and the second electrode. A liquid crystal display element having a first region,
Formed on at least one of the first electrode and the second electrode in a second region where the liquid crystal is inclined in a direction different from the first region by applying the voltage near the edge of the pixel. A liquid crystal display element having an opening of a small piece.   The liquid crystal display element according to claim 1, wherein the opening has a size that does not prevent the liquid crystal from being inclined by applying a voltage between the first electrode and the second electrode. .   The liquid crystal display element according to claim 1, wherein the opening has a width in a range of 3 μm to 6 μm, and has a rectangular or circular shape.   A plurality of the openings are arranged, and an arrangement interval of the openings is in a range of 3 μm to 20 μm in the pretilt angle forming direction, and in a range of 4 μm to 20 μm in a direction orthogonal to the pretilt angle forming direction. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element. The formation direction of the pretilt angle of the liquid crystal coincides with one of the first direction and the second direction,
The opening is disposed in the vicinity of an edge in a direction opposite to a direction in which the liquid crystal of the pixel is tilted, of edges located in a direction orthogonal to the formation direction of the pretilt angle of the pixel. 5. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element. The formation direction of the pretilt angle of the liquid crystal coincides with one of the first direction and the second direction,
The liquid crystal display element according to claim 1, wherein the opening is disposed in the vicinity of an edge of the pixel that is located in a direction parallel to a direction in which the pretilt angle is formed.

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