JP2008164983A - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VA type liquid crystal display element wherein arrangement of a liquid crystal can be made more uniform by reducing alignment disorder upon voltage application and luminance in a pixel can be enhanced. <P>SOLUTION: In each F electrode 121, a slit 121A having a width b is formed in a direction orthogonal to a longitudinal direction of the F electrode 121. In each F electrode 121, a region 121B having a width c protruding from a pixel region (a part region where the F electrode 121 and an R electrode 141 are superposed on each other) exists on an alignment treatment direction side of the pixel region. Since the region 121B exists, the width b of the slit 121A is made narrower than an interline width a. In the R electrode 141 whose longitudinal direction is orthogonal to the alignment treatment direction, a slit 141A having a width d equal to the interline width a is formed in a direction orthogonal to the longitudinal direction of the R electrode 141. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element in which the initial alignment of liquid crystal is vertical alignment, and more particularly to a liquid crystal display element that can reduce alignment disorder.

  As a liquid crystal display element, a liquid crystal display element (VA) in which the alignment (initial alignment) of liquid crystals (liquid crystal molecules) in the liquid crystal layer when no voltage is applied is substantially vertical to the substrate surface (VA: Vertical Alignment). Type liquid crystal display element). In the VA liquid crystal display element, a liquid crystal having negative dielectric anisotropy is used. Then, by applying a voltage to the liquid crystal layer, the liquid crystal is brought into a lying state (a state in which the liquid crystal layer is almost horizontal with respect to the substrate surface) (see, for example, Patent Document 1). The VA type liquid crystal display element has higher responsiveness and can realize a high contrast display compared with a TN (Twisted Nematic) type liquid crystal display element or an STN (Super Twisted Nematic) type liquid crystal display element (for example, patents). Reference 2).

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 when the voltage is applied cannot be defined. As a result, the alignment of the liquid crystal is not uniform and the display quality is lowered. Therefore, it is necessary to define the direction in which the liquid crystal tilts by applying a pretilt by some method or by devising the electrode shape. As a method of pre-tilting or devising the electrode shape to define the direction in which the liquid crystal tilts, the oblique electric field method in which the electric field direction by the applied voltage is oblique to the substrate surface, the rib method in which a rib structure is provided on the electrode, etc., oxidation There is an oblique deposition method in which silicon (SiO ₂ ) is obliquely deposited on a substrate. In addition, the alignment direction of the liquid crystal can be defined by performing a rubbing treatment on the alignment film made of vertical alignment.

  As a method for defining the alignment direction of the liquid crystal, there is a method of forming a slit in an electrode (see, for example, Patent Document 3).

JP 2003-207782 A (paragraphs 0002-0004) JP 2006-11362 A (paragraph 0014) Japanese Patent Laying-Open No. 2005-115143 (paragraphs 0004 and 0010)

  FIG. 18A is an exploded perspective view illustrating a configuration example of a general VA liquid crystal display element. The liquid crystal display element 1 is formed between two substrates (not shown) such as glass, and is viewed from the front side (front side) to the front side (F) polarizing plate 11, an F electrode portion 12 composed of a large number of electrodes, and a liquid crystal layer 13. The rear (R) electrode portion 14 and the R polarizing plate 15 made of a large number of electrodes are laminated.

  FIG. 18B is a plan view when only the F electrode portion 12 and the R electrode portion 14 are viewed from the front side. As shown in FIG. 18B, the plurality of F electrodes 121 in the F electrode portion 12 and the plurality of R electrodes 141 in the R electrode portion 14 are arranged to intersect each other. In the example shown in FIG. 18B, the F electrode 121 extends in the horizontal direction, and the R electrode 141 extends in the vertical direction. The liquid crystal display element 1 is a passive liquid crystal display element that does not have an active element such as a TFT (Thin Film Transistor).

  FIG. 19 is a plan view showing one pixel formed in a region where the F electrode 121 and the R electrode portion 14 intersect in the liquid crystal layer 13. Hereinafter, the direction orthogonal to the plane of the substrate is the Z direction, the direction in which the F electrode 121 extends, that is, the longitudinal direction of the F electrode 121 is the X direction, and the direction in which the R electrode 141 extends, that is, the longitudinal direction of the R electrode 141 is the Y direction. . FIG. 19 shows that the liquid crystal in the liquid crystal layer 13 is vertically aligned when no voltage is applied. Since the F polarizing plate 11 and the R polarizing plate 15 are arranged so that the absorption axes of the respective polarizing plates are orthogonal to each other, black display is visually recognized in the state shown in FIG.

  When a voltage is applied to the liquid crystal layer 13, the liquid crystal is tilted, and the transmittance increases due to the birefringence of the liquid crystal. An oblique electric field is generated in the liquid crystal layer 13 so as to make the alignment of the liquid crystal uniform when a voltage is applied to the liquid crystal layer 13, but as described in the above-mentioned Patent Document 1 (paragraph 0004 of Patent Document 1). -0005), it is known that a uniform arrangement as a whole can be obtained by an oblique electric field, but locally non-uniform alignment (alignment disorder) occurs. The transmittance is lowered at the portion where the alignment is disturbed.

  FIG. 20 is a schematic diagram of a pixel for explaining alignment disturbance at the time of voltage application. FIG. 20A shows an example of the alignment direction of liquid crystals in one pixel on a plane parallel to the substrate surface in the central portion of the liquid crystal layer 13 in the Z direction. In FIG. 20, the direction of the white arrow indicates the alignment direction of the liquid crystal. FIG. 20B shows an example of the alignment direction of the liquid crystals in the cross section of one pixel in the Y direction. The right side in FIG. 20B corresponds to the upper side in FIG. FIG. 20C shows an example of the alignment direction of the liquid crystals in the cross section of one pixel in the X direction. Hereinafter, what is shown in FIG. 20A is called a Z cross section, what is shown in FIG. 20B is a Y cross section, and what is shown in FIG. 20C is an X cross section.

  In the Z cross section, alignment disorder occurs on the upper side, the lower side, and the right side in FIG. 20A (see FIG. 20D). In particular, in the central portion of the liquid crystal layer 13 in the Z direction, the liquid crystal is affected by the oblique electric field of the R electrode 141 in the upper and lower portions (upper and lower portions in the pixel) of the pixel, and R An alignment disorder that tends to incline in the direction of the electrode portion 14 occurs, and the transmittance decreases because it approaches the absorption axis of the polarizing plate or a direction perpendicular thereto. In FIG. 20, a broken line indicates a relative transmittance in the pixel of the liquid crystal display element 1 when a voltage is applied with respect to a transmittance when no voltage is applied.

  Further, in the right part of the pixel (the right part in the pixel), the liquid crystal is affected by the oblique electric field of the F electrode 121, and alignment disorder is caused to tilt in the direction opposite to the direction in which the liquid crystal should originally tilt. The transmittance decreases. In this specification, a region where the liquid crystal is inclined in the reverse direction is referred to as a domain. In addition, the region in which the alignment is disturbed includes a domain (in this example, the right portion) and a region (in this example, an upper portion and a lower portion) in which the degree of inclination is different from the surroundings.

  As described above, the VA liquid crystal display element has a problem that the alignment is locally disturbed by the oblique electric field, and the transmittance is lowered in the region where the alignment is disturbed, so that the contrast is lowered.

  Accordingly, an object of the present invention is to provide a VA-type liquid crystal display element capable of reducing alignment disorder when a voltage is applied, making liquid crystal alignment more uniform, and improving the brightness in a pixel. .

  The liquid crystal display element according to the present invention includes a plurality of first electrodes arranged in the horizontal direction in the display area, a plurality of second electrodes arranged in the vertical direction in the display area so as to intersect the first electrode, A liquid crystal display element comprising a liquid crystal layer provided between an electrode and a second electrode and having a vertical alignment of liquid crystal when no voltage is applied, the longitudinal direction of the first electrode and the second electrode A slit having the same width as the inter-electrode distance is formed in the electrode orthogonal to the alignment treatment direction. Of the first electrode and the second electrode, the electrode having the same longitudinal direction as the alignment treatment direction is Also, a narrow slit is formed. Note that the same width means an equivalent width including allowable dimensions.

  It is preferable that anti-parallel rubbing treatment is performed on the alignment film formed on the plurality of first electrodes and the alignment film formed on the plurality of second electrodes.

  The alignment treatment direction is preferably the same as the longitudinal direction of the first electrode or the longitudinal direction of the second electrode.

  The alignment treatment direction side of the electrode in which the slit having a width narrower than the distance between the electrodes is formed is formed so as to protrude from the overlapping region with the other electrode (for example, the R electrode 141 with respect to the F electrode 121). It is preferable.

  According to the present invention, in the VA type liquid crystal display element, the alignment disorder caused by the oblique electric field can be reduced and the alignment of the liquid crystal can be made more uniform, and the brightness of the pixel is improved and the display quality is improved. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The overall configuration of the liquid crystal display element according to the present invention is the same as the configuration shown in FIG. That is, the liquid crystal display element 1 is formed between two substrates, such as glass, from the viewing side (front side) to the front side (F) polarizing plate 11, F electrode part 12, liquid crystal layer 13, and rear side (R) electrode part. 14 and the R polarizing plate 15 are laminated. In FIG. 18A, the substrate is not shown.

  FIG. 1A is a plan view showing the F electrode portion 12 in the liquid crystal display element according to the present invention. The F electrode portion 12 is provided with a plurality of strip-shaped F electrodes 121 extending in the horizontal direction. FIG. 1A shows a part of the three F electrodes 121 in the F electrode portion 12. ing. Actually, each F electrode 121 further extends in the left-right direction in FIG. The width between the F electrodes 121 (between lines), that is, the distance between the electrodes is a. Hereinafter, the distance between the electrodes may be simply referred to as “between lines”. FIG. 1B is a plan view showing the R electrode portion 14 in the liquid crystal display element according to the present invention. FIG. 1B shows a part of the three R electrodes 141 in the R electrode portion 14. Actually, each R electrode 141 further extends in the vertical direction in FIG. The distance between the lines of each R electrode 141 is the same as the distance between the lines of each F electrode 121.

  In addition, a vertical alignment film is formed on the liquid crystal layer 13 side of the F electrode portion 12 and the liquid crystal layer 13 side of the R electrode portion 14, and the F-side alignment film has the F electrode portion 12 in FIG. A rubbing process (orientation process) is performed in the longitudinal direction from the left side to the right side. In addition, the R-side alignment film is subjected to a rubbing process (alignment process) in a direction from the right side to the left side in the longitudinal direction of the F electrode portion 12 in FIG. That is, the anti-parallel (anti-parallel) rubbing process is applied to the F-side alignment film and the R-side alignment film in one direction. Further, in FIG. 1, the liquid crystal is subjected to processing (for example, formation of a pretilt) so as to tilt from the left side to the right side when a voltage is applied.

  FIG. 1C is a plan view when only the F electrode portion 12 and the R electrode portion 14 are viewed from the front side. In the display area (viewable area), as shown in FIG. 1C, the plurality of F electrodes 121 and the plurality of R electrodes 141 are arranged to intersect each other. The liquid crystal display element 1 is a passive liquid crystal display element that does not have an active element such as a TFT, and is driven line-sequentially using, for example, the F electrode portion 12 as a signal electrode and the R electrode as a scanning electrode. When the liquid crystal display element 1 is applied to a transmissive liquid crystal display panel, for example, a backlight is installed on the back surface (rear side) of the R polarizing plate 15.

  As shown in FIG. 1, a slit 121 </ b> A having a width b is formed in each F electrode 121 in a direction orthogonal to the longitudinal direction of the F electrode 121. In addition, the F electrode 121 is a region (hereinafter, referred to as a width c) exceeding the pixel region on the alignment processing direction side (left side in FIG. 1A) of the pixel (a portion where the F electrode 121 and the R electrode 141 overlap). , Referred to as an over-pixel region) 121B exists. Due to the existence of the pixel excess region 121B, the width b of the slit 121A is smaller than the line a.

  The R electrode 141 whose longitudinal direction is orthogonal to the alignment treatment direction has a slit 141A having the same width as the line a (specifically, an equivalent width including allowable dimensions) d in the direction orthogonal to the longitudinal direction of the R electrode 141. Is formed.

  The reason why the slits 121A and 141A as described above are provided in the F electrode 121 and the R electrode 141 will be described below.

  FIG. 2 shows the case where the line width of the F electrode 121 and the R electrode 141 is 180 μm, the line spacing is 20 μm (see FIG. 2D), and a voltage of 3.0 V (driving voltage) is applied to the liquid crystal layer 13. It is a schematic diagram which shows the arrangement direction of the liquid crystal in one pixel. 2A shows a Z cross section of the liquid crystal layer 13, FIG. 2B shows a Y cross section, and FIG. 2C shows an X cross section. In FIG. 2, the broken line indicates the relative transmittance of the liquid crystal display element 1 when a voltage is applied to the transmittance when no voltage is applied. In addition, the physical property value etc. of the liquid crystal layer 13 are the same as the physical property value etc. in the Example mentioned later.

  As shown in FIG. 2, a domain occurs in the right part of the pixel. As a result, on the right side of FIG. In addition, alignment disorder occurs in the upper and lower portions of the pixel. As a result, there are portions where the transmittance is greatly reduced on both the left and right sides in FIG. The state shown in the schematic diagram of FIG. 2 is obtained when the rubbing direction of the alignment film is 0 ° (the same direction as the longitudinal direction of the F electrode 121).

  FIG. 3 is a schematic diagram showing the alignment direction of the liquid crystal in one pixel when slits 121A and 141A are provided in the F electrode 121 and the R electrode 141, and a voltage (drive voltage) of 3.0 V is applied to the liquid crystal layer 13. is there. As shown in FIG. 3D, a slit 121A having a width of 20 μm is formed in the F electrode 121 extending in the lateral direction so as to cut from both the upper and lower sides. In FIG. 3D, only a portion corresponding to one pixel in one F electrode 121 is shown, so that it is described as 10 μm. However, when the adjacent pixel portion is included, the width of the slit 121A is 20 μm. .

  In addition, a slit 141A having a width of 20 μm is formed in the R electrode 141 extending in the vertical direction so as to cut from both the left and right sides. In FIG. 3D, only a portion corresponding to one pixel in one R electrode 141 is shown, so it is described as 10 μm. However, including the adjacent pixel portion, the width of the slit 141A is 20 μm. . In FIG. 3D, a solid line arrow in the pixel indicates the alignment process direction of the alignment film on the F electrode side, and a broken line arrow indicates the alignment process direction of the alignment film on the R electrode side.

  When an electrode is formed as shown in FIG. 3D and a voltage of 3.0 V is applied to the liquid crystal layer 13, as shown in FIGS. 3A and 3B, compared to the case shown in FIG. The domain of the right part of the pixel is improved. That is, the domain area becomes smaller. Also, the alignment disturbance of the upper and lower portions of the pixel is improved, that is, the degree of alignment disturbance is reduced. However, a new alignment disorder occurs in the left part of the pixel.

  In FIG. 4, in order to improve the alignment disorder in the left part of the pixel, slits 121 </ b> A and 141 </ b> A are provided in the F electrode 121 and the R electrode 141, and an excess pixel region 121 </ b> B is provided in the F electrode 121. It is a schematic diagram which shows the arrangement direction of the liquid crystal in one pixel at the time of applying the voltage (drive voltage) of 3.0V. The width of the pixel excess region 121B is 10 μm, which is 1/2 of 20 μm between lines. Considering the pixel excess region 121B in the adjacent pixel, the F electrode 121 extending in the horizontal direction is formed with a slit 121A having a width of 10 μm so as to cut from both the upper and lower sides. In the pixel excess region 121B, an oblique electric field can be used effectively.

  In addition, a slit 141A having a width of 20 μm cut from the right side is formed in the R electrode 141 extending in the vertical direction. In FIG. 4D, only a portion corresponding to one pixel in one R electrode 141 is shown, so it is described as 10 μm. However, including the adjacent pixel portion, the width of the slit 141A is 20 μm. . In FIG. 4D, a solid line arrow in the pixel indicates the alignment process direction of the alignment film on the F electrode side, and a broken line arrow indicates the alignment process direction of the alignment film on the R electrode side.

  When an electrode is formed as shown in FIG. 4D and a voltage of 3.0 V is applied to the liquid crystal layer 13, as shown in FIGS. 4A and 4B, compared to the case shown in FIG. The domain of the left part of the pixel is improved. That is, the domain area becomes smaller. However, the degree of alignment disturbance in the right side portion of the pixel is larger than that shown in FIG.

  FIG. 5 shows a case where the width of the pixel excess region 121B is reduced to 5 μm to the F electrode 121 and a voltage (drive voltage) of 3.0 V is applied to the liquid crystal layer 13 as compared with the case shown in FIG. It is a schematic diagram which shows the arrangement direction of the liquid crystal in a pixel. Since the width of the pixel excess area 121B is 5 μm, the width of the slit 121A is 15 μm in consideration of the pixel excess area 121B in the adjacent pixel. In FIG. 5D, a solid line arrow in the pixel indicates the alignment processing direction of the alignment film on the F electrode side, and a broken line arrow indicates the alignment processing direction of the alignment film on the R electrode side.

  When the electrodes are formed as shown in FIG. 5D, the liquid crystal alignment directions are substantially aligned. Also, no domain has occurred. As a result, the degree of change in the transmittance within the pixel when a voltage is applied is smaller than in the case shown in FIG. Specifically, in the upper part, the lower part, and the right part of the pixel, the transmittance does not decrease much compared to the case shown in FIG.

  From the above results, as shown in FIG. 6 showing the formation positions and the like of the slits 121A and 141A, in the portion corresponding to the line between the F electrodes 121 in the R electrode 141 whose longitudinal direction is orthogonal to the alignment treatment direction, the line a 141A (see FIG. 6B), and in the F electrode 121 whose longitudinal direction coincides with the alignment treatment direction, between the lines of the R electrode 141 on the side where the liquid crystal falls (right side in FIG. 6) A slit 121A having a width narrower than the line a is provided in the corresponding portion, and a portion corresponding to the space between the lines of the R electrode 141 on the opposite side (left side in FIG. 6) to the direction in which the liquid crystal is tilted is formed with respect to the slit 121A. By providing the electrode excess portion 121B, the alignment disorder of the liquid crystal can be reduced.

  6B shows two pixels shown in FIG. 5B, and FIG. 6C shows two pixels shown in FIG. 5C. Has been. In FIG. 6C, a solid line arrow in the pixel indicates the alignment process direction of the alignment film on the F electrode side, and a broken line arrow indicates the alignment process direction of the alignment film on the R electrode side.

  Hereinafter, specific examples will be described.

(Example 1)
The F electrode 121 is patterned on the glass substrate on the F side (viewing side, front side) so that the line width is 180 μm and the space between the lines is 20 μm, and a slit 121A of 15 μm is formed at the position shown in FIG. The R side (anti-viewing side, rear side) glass substrate has a line width of 180 μm and a line spacing of 20 μm, and a slit of 141 μm of 20 μm is formed at a position as shown in FIG. The electrode 141 was patterned. Since the pixel excess region 121B exists on the alignment processing direction side in the F electrode 121 in which the slit 121A having a width narrower than the line a is formed, the F electrode 121 protrudes from the overlapping region with the R electrode 141. It is formed to do.

  Next, vertical alignment films are formed on the F side and the R side, and as shown in FIG. 7B, antiparallel (antiparallel) to the F side alignment film and the R side alignment film. ) A rubbing treatment was performed to set the pretilt angle to 89.6 ° and the retardation Δn · d to 538 nm as shown in FIG. The angle when the liquid crystal molecules are in a completely vertical state is 90 °. As the liquid crystal material, as shown in FIG. 8B, a material having a refractive index anisotropy (Δn) of 0.0896 and a dielectric anisotropy (Δε) of −5.6 was used. As shown in FIG. 8 (A), the cell gap was set to 6.0 μm.

As the polarizing plates 11 and 15, NPF-SEG1224DU manufactured by Nitto Denko Corporation was used. As shown in FIGS. 7A and 7C, the F polarizing plate (first polarizing plate) 11 absorbs from the reference axis when viewed from the viewing side, with the alignment treatment direction of the F side alignment film as the reference axis. When the counterclockwise angle to the axis is θ ₁ , θ ₁ = 45 °, and the counterclockwise angle to the absorption axis of the R polarizing plate (second polarizing plate) 15 is θ ₂ . In this case, θ ₂ = 135 °. Although the absorption axes of the polarizing plates 11 and 15 are orthogonal to each other here, the polarization axes may be orthogonal to each other.

  FIG. 9A is a plan view showing the shape of the F electrode 121 of this embodiment as viewed from the viewing side, and FIG. 9B is a plan view showing the shape of the R electrode 141 of this embodiment. . FIG. 9C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side. In FIG. 9, “a” indicates the space between the F electrode 121 and the R electrode 141, “b” indicates the width of the slit 121A, “c” indicates the width of the over-pixel region, and “d” indicates the slit 141A. Indicates the width.

  In this embodiment, a slit 141A having the same width (20 μm) as the line a is formed in the R electrode 141 whose longitudinal direction is orthogonal to the alignment treatment direction, and the F electrode 121 whose longitudinal direction is the same as the alignment treatment direction. A slit 121A narrower than the line a is formed, and the F electrode 121 is 5 μm wider than the pixel on the left side of the pixel.

  When the liquid crystal display element 1 produced as described above was driven at a duty ratio of 1/32, good visibility was obtained. That is, a good black display was obtained when no voltage was applied or when the voltage was off (OFF), and a bright white display was obtained when the voltage was turned on (ON).

(Comparative Example 1)
FIG. 10A is a plan view showing the shape of the F electrode 121 viewed from the viewing side of the first comparative example (comparative example 1), and FIG. 10B is the R electrode of the first comparative example. It is a top view which shows the shape of 141. FIG. FIG. 10C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side.

  In the first comparative example, slits 121A and 141A are not formed in the electrodes, and the F electrode 121 is patterned on the F side glass substrate so that the line width is 180 μm and the line spacing is 20 μm, and the R side glass substrate is formed. The R electrode 141 was patterned so that the line width was 180 μm and the line spacing was 20 μm. Others were the same as in the case of the first example (Example 1), and were driven with a duty ratio of 1/32.

  In the first comparative example, the brightness at the time of turning on (when applying the on voltage) was lowered, and the visibility was lowered as compared with the case of the first example. The reason is that, as described above, in the central portion in the Z direction of the liquid crystal layer 13, the liquid crystal is affected by the oblique electric field of the R electrode 141 in the upper and lower portions of the pixel, and the R electrode portion 14 This is because an alignment disorder that tends to tilt in the direction occurs, and the transmittance decreases because it approaches the absorption axis of the polarizing plate or a direction perpendicular thereto. Further, in the right part of the pixel, the liquid crystal is affected by the oblique electric field of the F electrode 121, causing an alignment disorder in which the liquid crystal tends to tilt in a direction opposite to the direction in which the liquid crystal should originally tilt, and the transmittance is lowered. is there. In other words, compared with the first comparative example, in the first embodiment, the influence of the oblique electric field when a voltage is applied is reduced in the upper part, the lower part and the right part of the pixel. The disturbance of the liquid crystal alignment in the central portion of the liquid crystal layer 13 is reduced, and the brightness in the pixel at the on time is improved.

(Comparative Example 2)
FIG. 11A is a plan view showing the shape of the F electrode 121 viewed from the viewing side of the second comparative example (comparative example 2), and FIG. 11B is the R electrode of the second comparative example. It is a top view which shows the shape of 141. FIG. FIG. 11C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side.

  In the second comparative example, a slit is formed in the F electrode 121 on the F side glass substrate, the F electrode 121 is patterned so that the line width is 180 μm and the line spacing is 20 μm, and the R side glass substrate is formed. The R electrodes 141 were patterned so that slits were formed in the R electrodes 141, the line width was 180 μm, and the line spacing was 20 μm. Others were the same as in the case of the first example (Example 1), and were driven with a duty ratio of 1/32.

  Compared with the first comparative example, the influence of an oblique electric field when a voltage is applied to the upper part and the lower part of the pixel is reduced, and the alignment disorder of the liquid crystal in the central part of the liquid crystal layer 13 in the pixel is reduced. , The brightness in the pixel when on was improved. However, the liquid crystal alignment disorder occurred in the left part of the pixel, and the brightness in the pixel at the time of ON was lowered and the visibility was lowered as compared with the first example.

(Example 2)
The F electrode 121 is patterned on the F side glass substrate so that the line width is 180 μm and the line spacing is 20 μm, and the slit 121A of 20 μm is formed, and the line width is 180 μm on the R side glass substrate. The R electrode 141 was patterned so that a slit 141A of 15 μm was formed. Since the pixel excess region 141B exists on the alignment processing direction side in the R electrode 141 in which the slit 141A having a width narrower than the line spacing a is formed, the R electrode 141 protrudes from the overlapping region with the F electrode 121. It is formed to do.

  Next, vertical alignment films are formed on the F side and the R side, and as shown in FIG. 12B, antiparallel (antiparallel) to the F side alignment film and the R side alignment film. ) A rubbing treatment was performed so that the pretilt angle was 89.6 ° and the retardation Δn · d was 538 nm. A liquid crystal material having a refractive index anisotropy (Δn) of 0.0896 and a dielectric anisotropy (Δε) of −5.6 was used. The cell gap was 6.0 μm.

As the polarizing plates 11 and 15, NPF-SEG1224DU manufactured by Nitto Denko Corporation was used. As shown in FIGS. 12A and 12C, the F polarizing plate (first polarizing plate) 11 absorbs from the reference axis when viewed from the viewing side, with the alignment treatment direction of the F side alignment film as the reference axis. When the counterclockwise angle to the axis is θ ₁ , θ ₁ = 45 °, and the counterclockwise angle to the absorption axis of the R polarizing plate (second polarizing plate) 15 is θ ₂ . In this case, θ ₂ = 135 °. Although the absorption axes of the polarizing plates 11 and 15 are orthogonal to each other here, the polarization axes may be orthogonal to each other.

  FIG. 13A is a plan view showing the shape of the F electrode 121 of this embodiment as viewed from the viewing side, and FIG. 13B is a plan view showing the shape of the R electrode 141 of this embodiment. . FIG. 13C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side. In FIG. 13, “a” indicates the space between the F electrode 121 and the R electrode 141, “b” indicates the width of the slit 121 A, “d” indicates the width of the slit 141 A, and “e” indicates the R electrode 141. The width of the pixel excess area 141B in FIG.

  In this embodiment, the slit 121A having the same width (20 μm) as the line a is formed in the F electrode 121 whose longitudinal direction is orthogonal to the alignment treatment direction, and the longitudinal direction is the same as the alignment treatment direction in the R electrode 141. A slit 141A narrower than the line a is formed, and the R electrode 141 is 5 μm wider than the pixel in the upper part of the pixel. That is, the configuration of the F electrode 121 and the shape of the R electrode 141 are reversed with respect to the configuration of the first embodiment.

  When the liquid crystal display element 1 produced as described above was driven at a duty ratio of 1/32, good visibility was obtained. That is, a good black display was obtained when no voltage was applied or when the voltage was off (OFF), and a bright white display was obtained when the voltage was turned on (ON).

(Comparative Example 3)
FIG. 14A is a plan view showing the shape of the F electrode 121 viewed from the viewing side of the third comparative example (comparative example 3), and FIG. 14B is the R electrode of the third comparative example. It is a top view which shows the shape of 141. FIG. FIG. 14C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side.

  In the third comparative example, slits 121A and 141A are not formed in the electrodes, and the F electrode 121 is patterned on the F side glass substrate so that the line width is 180 μm and the line spacing is 20 μm, and the R side glass substrate is formed. The R electrode 141 was patterned so that the line width was 180 μm and the line spacing was 20 μm. Others were the same as in the case of the second example (Example 2), and were driven with a duty ratio of 1/32.

  In the 3rd comparative example, the brightness at the time of ON fell, and visibility fell compared with the case of the 2nd example. The reason is that in the central portion in the Z direction of the liquid crystal layer 13, the liquid crystal tends to tilt toward the F electrode portion 12 due to the influence of the oblique electric field of the F electrode 121 in the right and left portions of the pixel. This is because the alignment is disturbed and the transmittance decreases because it approaches the absorption axis of the polarizing plate or a direction perpendicular thereto. In the lower part of the pixel, the liquid crystal is affected by the oblique electric field of the R electrode 141, causing an alignment disorder in which the liquid crystal tends to tilt in a direction opposite to the direction in which the liquid crystal should originally tilt, and the transmittance decreases. It is. In other words, compared with the third comparative example, in the second embodiment, the influence of the oblique electric field when a voltage is applied is reduced in the right side portion, the left side portion, and the lower side portion of the pixel. The disturbance of the liquid crystal alignment in the central portion of the liquid crystal layer 13 is reduced, and the brightness in the pixel at the on time is improved.

(Example 3)
The F electrode 121 is patterned on the F side glass substrate so that the line width is 180 μm and the line spacing is 20 μm, and the slit 121A of 20 μm is formed, and the line width is 180 μm on the R side glass substrate. The R electrode 141 was patterned so that a slit 141A of 15 μm was formed. Since the pixel excess region 141B exists on the alignment processing direction side in the R electrode 141 in which the slit 141A having a width narrower than the line spacing a is formed, the R electrode 141 protrudes from the overlapping region with the F electrode 121. It is formed to do.

  Next, vertical alignment films are formed on the F side and the R side, and as shown in FIG. 7B, antiparallel (antiparallel) to the F side alignment film and the R side alignment film. ) A rubbing treatment was performed so that the pretilt angle was 89.6 ° and the retardation Δn · d was 538 nm. A liquid crystal material having a refractive index anisotropy (Δn) of 0.0896 and a dielectric anisotropy (Δε) of −5.6 was used. The cell gap was 6.0 μm.

As the polarizing plates 11 and 15, NPF-SEG1224DU manufactured by Nitto Denko Corporation was used. As shown in FIGS. 7A and 7C, the F polarizing plate (first polarizing plate) 11 absorbs from the reference axis when viewed from the viewing side, with the alignment treatment direction of the F side alignment film as the reference axis. When the counterclockwise angle to the axis is θ ₁ , θ ₁ = 45 °, and the counterclockwise angle to the absorption axis of the R polarizing plate (second polarizing plate) 15 is θ ₂ . In this case, θ ₂ = 135 °. Although the absorption axes of the polarizing plates 11 and 15 are orthogonal to each other here, the polarization axes may be orthogonal to each other.

  FIG. 15A is a plan view showing the shape of the F electrode 121 of this embodiment as viewed from the viewing side, and FIG. 15B is a plan view showing the shape of the R electrode 141 of this embodiment. . FIG. 15C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side. In FIG. 15, “a” indicates the space between the F electrode 121 and the R electrode 141, “b” indicates the width of the slit 121 A, “d” indicates the width of the slit 141 A, and “e” indicates the R electrode 141. The width of the pixel excess area 141B in FIG.

  In this embodiment, the slit 121A having the same width (20 μm) as the line a is formed in the F electrode 121 whose longitudinal direction is orthogonal to the alignment treatment direction, and the longitudinal direction is the same as the alignment treatment direction in the R electrode 141. A slit 141A narrower than the line a is formed, and the R electrode 141 is 5 μm wider than the pixel in the right portion of the pixel.

  When the liquid crystal display element 1 produced as described above was driven at a duty ratio of 1/32, good visibility was obtained. That is, a good black display was obtained when no voltage was applied or when the voltage was off (OFF), and a bright white display was obtained when the voltage was turned on (ON).

(Comparative Example 4)
FIG. 16A is a plan view showing the shape of the F electrode 121 viewed from the viewing side of the fourth comparative example (Comparative Example 4), and FIG. 16B is the R electrode of the fourth comparative example. It is a top view which shows the shape of 141. FIG. FIG. 16C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side.

  In the fourth comparative example, slits 121A and 141A are not formed in the electrode, and the F electrode 121 is patterned on the F side glass substrate so that the line width is 180 μm and the line spacing is 20 μm, and the R side glass substrate is formed. The R electrode 141 was patterned so that the line width was 180 μm and the line spacing was 20 μm. Others were the same as in the case of the third example (Example 3), and were driven with a duty ratio of 1/32.

  In the 4th comparative example, the brightness at the time of ON fell, and the visibility fell compared with the case of the 3rd example. The reason is that in the central portion of the liquid crystal layer 13 in the Z direction, the liquid crystal is inclined in the direction of the F electrode portion 12 due to the influence of the oblique electric field of the F electrode 121 in the upper and lower portions of the pixel. This is because the alignment is disturbed and approaches the absorption axis of the polarizing plate or a direction perpendicular thereto, and thus the transmittance decreases. Further, in the left part of the pixel, the liquid crystal is affected by the oblique electric field of the R electrode 121, causing an alignment disorder in which the liquid crystal tends to tilt in a direction opposite to the direction in which the liquid crystal should originally tilt, and the transmittance is lowered. is there. In other words, compared with the fourth comparative example, in the third embodiment, the influence of the oblique electric field when a voltage is applied is reduced in the upper part, the lower part, and the left part of the pixel. The disturbance of the liquid crystal alignment in the central portion of the liquid crystal layer 13 is reduced, and the brightness in the pixel at the on time is improved.

Example 4
In the first to third embodiments, all the slits 121 </ b> A are formed so as to cut from one side in a direction orthogonal to the longitudinal direction of the F electrode 121. Further, all the slits 141 </ b> A were formed so as to cut from one side in a direction orthogonal to the longitudinal direction of the R electrode 141. However, as shown in FIG. 17, it may be formed so as to cut from both sides.

  FIG. 17A is a plan view showing the shape of the F electrode 121 viewed from the viewing side of the fourth embodiment (embodiment 4), and FIG. 17B is the R electrode of the fourth embodiment. It is a top view which shows the shape of 141. FIG. FIG. 17C is a plan view when the F electrode 121 and the R electrode 141 are viewed from the viewing side. The widths of the slits 121A and 141A are the same as those in the first embodiment.

  Also in this example, good visibility was obtained. That is, a good black display was obtained when no voltage was applied or when the voltage was off (OFF), and a bright white display was obtained when the voltage was turned on (ON).

  In this embodiment, all the slits 121A and 141A are formed so as to cut from both sides, but the slits 121A may be formed so as to cut alternately from both sides in the longitudinal direction of the F electrode 121. In the longitudinal direction of the R electrode 141, it may be formed so as to cut alternately from both sides.

  In addition, it is preferable that (DELTA) n * d of the liquid crystal layer 13 is 200-1000 nm. This is because when the voltage is smaller than 200 nm, the brightness when the on-state voltage is applied is lowered and the contrast is lowered, and when it is larger than 1000 nm, the color is colored when the on-voltage is applied and it becomes difficult to display black and white. The pretilt angle of the liquid crystal is preferably 85 to 89.8 °. When the angle is smaller than 85 °, the brightness is reduced when no voltage is applied or when the voltage is off (OFF) and the contrast is lowered. When the voltage is larger than 89.8 °, the direction in which the liquid crystal tilts when the voltage is applied is uniform. This is because the alignment is disturbed.

  Further, the alignment treatment direction is preferably the same direction as either the longitudinal direction of the F electrode 121 or the longitudinal direction of the R electrode 141, as shown in each example. This is because the alignment disorder of the liquid crystal is reduced.

  In each of the above embodiments, the line spacing is 20 μm, but when the line spacing is 20 to 40 μm, a slit having the same width as the line is formed on the electrode whose longitudinal direction is orthogonal to the alignment treatment direction. A slit having a width of 15 to 35 μm may be formed on the electrode whose direction is the same as the alignment treatment direction. That is, [width of slit provided in electrode whose longitudinal direction is orthogonal to alignment treatment direction> width of slit provided in electrode whose longitudinal direction is the same as the alignment treatment direction. The “same width” includes not only the case where they are exactly the same but also the case where there is a difference due to a manufacturing error or the like.

  The present invention can be applied to improve display quality in a VA liquid crystal display element.

The top view at the time of seeing the F electrode part and R electrode part in the liquid crystal display element by this invention from the front side. The schematic diagram which shows the arrangement direction of a liquid crystal in case the line | wire width of an electrode is 180 micrometers, line | wire spacing is 20 micrometers, and the applied voltage is 3.0V. The schematic diagram which shows the arrangement direction of the liquid crystal at the time of the voltage application in the example which provided the slit in F electrode and R electrode. The schematic diagram which shows the arrangement direction of the liquid crystal at the time of the voltage application in the other example which provided the slit in F electrode and R electrode. The schematic diagram which shows the arrangement direction of the liquid crystal at the time of the voltage application in the further another example which provided the slit in F electrode and R electrode. Explanatory drawing which shows the formation position etc. of a slit. Explanatory drawing which shows the absorption-axis direction of a polarizing plate, and the orientation process direction of an orientation film. Explanatory drawing which shows a panel specification and a liquid-crystal physical property value. The top view which shows the shape of F electrode and R electrode of a 1st Example. The top view which shows the shape of F electrode and R electrode of a 1st comparative example. The top view which shows the shape of F electrode and R electrode of a 2nd comparative example. Explanatory drawing which shows the absorption-axis direction of a polarizing plate, and the orientation process direction of an orientation film. The top view which shows the shape of F electrode of a 2nd Example, and R electrode. The top view which shows the shape of F electrode of the 3rd comparative example, and R electrode. The top view which shows the shape of F electrode and R electrode of a 3rd Example. The top view which shows the shape of F electrode and R electrode of a 4th comparative example. The top view which shows the shape of F electrode and R electrode of a 4th Example. (A) is an exploded perspective view showing a configuration example of a general VA liquid crystal display element, and (B) is a plan view when the F electrode portion and the R electrode portion are viewed from the front side. The top view which shows one pixel. The schematic diagram of the pixel for demonstrating the alignment disorder at the time of a voltage application.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 11 F polarizing plate 12 F electrode part 13 Liquid crystal layer 14 R electrode part 15 R polarizing plate 121 F electrode 121A Slit 121B Excess pixel area 141 R electrode 141A Slit 141B Excess pixel area

Claims (4)

Between a plurality of first electrodes arranged in the horizontal direction in the display area, a plurality of second electrodes arranged in the vertical direction in the display area so as to intersect the first electrode, and between the first electrode and the second electrode In a liquid crystal display element provided with a liquid crystal layer in which the alignment of liquid crystal when no voltage is applied is a vertical alignment,
Of the first electrode and the second electrode, a slit having the same width as the inter-electrode distance is formed on the electrode whose longitudinal direction is orthogonal to the alignment treatment direction.
A liquid crystal display element, wherein a slit having a width smaller than an inter-electrode distance is formed in an electrode having a longitudinal direction the same as an alignment treatment direction of the first electrode and the second electrode. The liquid crystal display element according to claim 1, wherein an anti-parallel rubbing treatment is performed on the alignment film formed on the plurality of first electrodes and the alignment film formed on the plurality of second electrodes. The liquid crystal display element according to claim 1, wherein the alignment treatment direction is the same as the longitudinal direction of the first electrode or the longitudinal direction of the second electrode. The alignment treatment direction side of the electrode in which the slit having a width narrower than the distance between the electrodes is formed so as to protrude with respect to the overlapping region with the other electrode. 2. A liquid crystal display device according to item 1.

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