JP5774160B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device having a plurality of openings (slits) in an electrode.

  As an information display device, a display device having a very low display brightness of a background display portion or a dark display portion is required, and a vertical alignment type liquid crystal display device is known as one that can realize this. The vertical alignment type liquid crystal display device has almost the same optical characteristics when viewed from the front in the initial alignment state as that of the polarizing plate in the crossed Nicols arrangement, so the transmittance in the initial alignment state can be very low. It becomes.

  In the vertical alignment type liquid crystal display device as described above, in order to obtain good viewing angle characteristics even when a voltage is applied, the alignment direction of liquid crystal molecules is divided into a plurality of directions within one pixel (multi-domain alignment). Is effective, and various techniques have been proposed to realize this. For example, Japanese Patent No. 4107978 (Patent Document 1) discloses an electrode structure that realizes the above multi-domain alignment in a segment display type liquid crystal display device. In this liquid crystal display device, each of the vertically arranged upper and lower electrodes is provided with an elongated rectangular opening, and the upper and lower electrodes are arranged so that the openings of the upper electrode and the openings of the lower electrode are arranged alternately in a plan view. Is arranged. Thereby, since an oblique electric field can be generated around each opening, the alignment direction of the liquid crystal molecules can be rotated 180 ° with the opening as a boundary. In Patent Document 1, a liquid crystal display in which rectangular openings are alternately arranged on opposing upper and lower substrates as an electrode structure that is effective even for an arbitrary display pattern when mainly performing a character (segment) display pattern. An apparatus is disclosed.

  In the liquid crystal display device provided with a large number of rectangular openings as described above, the orientation of liquid crystal molecules may become non-uniform depending on the layout of the openings, resulting in problems such as a decrease in effective aperture ratio and a decrease in response speed when a voltage is applied. May occur. As one of solutions to these problems, Japanese Patent Application Laid-Open No. 2009-122271 (Patent Document 2) discloses that a plurality of rectangular openings provided on a substrate have two openings adjacent to each other in the long side direction. A technique is disclosed in which the distance between the openings is shorter than the length (slit width) of each opening in the short side direction. According to this, it is possible to eliminate problems due to in-plane etching unevenness or the like when patterning the electrode to form each opening.

  By the way, in the method proposed in Patent Document 2, when it is desired to further shorten the length of the opening in the short side direction, the distance between the openings in the long side direction is also shortened accordingly. There is a need. However, when the distance between the long sides of the openings is set shorter, depending on the patterning process conditions, for example, the adjacent openings may be coupled to each other under overetching conditions. When such a lot of coupling | bonding of opening parts generate | occur | produces, there exists a possibility that the raise of the resistance value of an electrode will be caused and display quality may fall. Further, if all the openings adjacent to each other in the long side direction are combined, the electrodes are disconnected, which may cause a display defect and reduce display quality.

Japanese Patent No. 4107978 JP 2009-122271 A

  A specific aspect of the present invention is to provide a technique capable of avoiding deterioration in display quality in a liquid crystal display device in which a plurality of openings are provided in an electrode.

A liquid crystal display device according to one embodiment of the present invention includes (a) a first substrate having a first electrode on one surface side, and (b) a second electrode on one surface side, and the second electrode and the first substrate. A second substrate disposed opposite to the first substrate so as to face the first electrode; (c) a vertical alignment liquid crystal layer provided between the first substrate and the second substrate; and (d) a first substrate. A pair disposed outside each of the substrate and the second substrate, the absorption axes of which are substantially orthogonal to each other, and each of the absorption axes is disposed at an angle of approximately 45 ° with respect to the first direction. (E) each of the first electrodes has a shape extending in the first direction, and has a plurality of first openings provided in a regular checkered pattern, (f) ) Each of the second electrodes has a shape extending in the first direction, and has a plurality of second openings provided in a regular checkered pattern, and (g) the plurality of first openings. As each located between two second adjacent openings in a plan view of the second opening more in either of the two directions perpendicular to the first direction and the first direction of the section, The plurality of first openings and the plurality of second openings are relatively disposed, and (h) each of the plurality of first openings and the plurality of second openings is in the first direction in plan view. Each of the adjacent one end portions is arranged so as to partially overlap each other. (I) Each of the plurality of first openings and the plurality of second openings has a length in the second direction of 0.007 mm or more. (J) When a voltage is applied between the first electrode and the second electrode, the liquid crystal layer corresponds to a position where the plurality of first openings and the plurality of second openings exist. No voltage is applied to each region, and each region is viewed from the outside of one of the pair of polarizing plates. It is observed as a dark area when a liquid crystal display device.

  According to the above-described liquid crystal display device, the distance between adjacent openings can be greatly increased in each of the first electrode and the second electrode. Thereby, an increase in resistance value and disconnection of the electrodes due to the coupling between the openings can be avoided, and a decrease in display quality can be avoided.

In the liquid crystal display device, a substantially rectangular pixel portion is defined by a region where the first electrode and the second electrode overlap in a plan view, and the plurality of first openings and the plurality of second openings are: In plan view, each other end portion is arranged so as to overlap with the edge portion of the pixel region, and each longitudinal direction is arranged so as to form an angle other than orthogonal to the extending direction of each edge portion of the pixel portion. It is also preferable.

Further, in the above liquid crystal display device, one display unit is defined for each region where the first electrode and the second electrode overlap in a plan view, and the inside of one display unit is divided into a plurality of regions. The first direction for defining the arrangement of each of the plurality of first openings and the plurality of second openings may be set in a different direction for each of the divided regions.

  In the above liquid crystal display device, the effective display area defined in the overlapping area of the first substrate and the second substrate is divided into a plurality of areas, and a plurality of first areas are divided for each of the divided areas. The first direction for defining the arrangement of each of the opening and the plurality of second openings may be set in a different direction.

It is the external appearance schematic diagram and partial enlarged view of the liquid crystal display device of one Embodiment. It is the fragmentary sectional view in the II-II 'line | wire of the liquid crystal display device shown in FIG. It is a typical top view which shows the structure of a 1st opening part and a 2nd opening part. It is a figure for demonstrating the condition setting of each opening part used for the simulation analysis. It is a figure which shows a simulation analysis result (in-plane transmittance | permeability distribution). It is a figure which shows the director distribution of the liquid crystal molecule in a liquid-crystal layer. It is a typical top view which shows the structure of the 1st opening part at the time of setting Ls to 0, and a 2nd opening part. It is a figure which shows the simulation analysis result (in-plane transmittance distribution) at the time of setting Ls to 0. It is a typical top view which shows the structure of the 1st opening part at the time of setting Ls to a negative value, and a 2nd opening part. It is a figure which shows the simulation analysis result (in-plane transmittance distribution) at the time of setting Ls to a negative value. It is a figure which shows the simulation analysis result (in-plane transmittance distribution) which set the chiral pitch p of the liquid crystal layer to 10 micrometers. It is a typical top view for demonstrating the case where the effective display part of a liquid crystal display device is divided | segmented into a some area | region. FIG. 11 is a schematic plan view for explaining a case where one segment display unit is divided into a plurality of regions in a liquid crystal display device that performs segment display with a relatively large display area. FIG. 6 is a schematic plan view for explaining a case where the length L in the longitudinal direction of each opening is set to be not equal in one pixel portion when the dot matrix type electrode structure is adopted. It is a figure which shows the image obtained by actually producing the liquid crystal display device which has each opening part of the structure shown in FIG. 14, and observing the one pixel part 1 by a reflective microscope. It is a figure which shows the polarizing microscope observation image of the pixel part at the time of the voltage application at the time of producing the liquid crystal display device shown in FIG. It is a figure for demonstrating the embodiment which changed the shape of each opening part. It is a figure which shows the simulation analysis result of the liquid crystal display device which has each opening part of the structure shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic external view and a partially enlarged view of a liquid crystal display device according to an embodiment. FIG. 2 is a partial cross-sectional view taken along the line II-II ′ of the liquid crystal display device shown in FIG. The liquid crystal display device of this embodiment shown in each figure includes an upper substrate (first substrate) 1, a plurality of upper electrodes (first electrodes) 2, an alignment film 3, a lower substrate (second substrate) 4, and a plurality of lower substrates. It includes a side electrode (second electrode) 5, an alignment film 6, a liquid crystal layer 7, an upper polarizing plate (first polarizing plate) 8, and a lower polarizing plate (second polarizing plate) 9.

  As shown in the partially enlarged view of FIG. 1, in the liquid crystal display device of the present embodiment, each of the portions (intersection regions) where the upper electrode 2 and the lower electrode 5 overlap in plan view is the pixel unit 11. That is, the liquid crystal display device of the present embodiment is a dot matrix type liquid crystal display device in which the pixel unit 11 is arranged in two directions of the row direction and the column direction. In FIG. 1, only one pixel portion 11 is colored. In the present embodiment, the widths of the upper electrode 2 and the lower electrode 5 are equal to each other, for example, set to 0.42 mm. Accordingly, the pixel unit 11 in the present embodiment has a square shape of 0.42 mm square. Further, the distance between two adjacent upper electrodes 2 is set to 0.03 mm, for example. Similarly, the distance between two adjacent lower electrodes 5 is set to 0.03 mm, for example.

  The upper substrate 1 and the lower substrate 4 are transparent substrates such as a glass substrate and a plastic substrate, respectively. Between the upper substrate 1 and the lower substrate 4, spacers (granular bodies) are dispersed and arranged. By these spacers, the gap between the upper substrate 1 and the lower substrate 4 is kept at a predetermined distance (for example, about 4.0 μm).

  The plurality of upper electrodes 2 are provided on one surface of the upper substrate 1. Each upper electrode 2 is formed in a strip shape (stripe shape), and extends in one direction on one surface of the upper substrate 1. In the present embodiment, each upper electrode 2 extends in the vertical direction (first direction) in FIG. Each upper electrode 2 is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example.

  The plurality of lower electrodes 5 are provided on one surface of the lower substrate 4. Each lower electrode 5 is formed in a belt shape and extends in one direction on one surface of the lower substrate 4. In the present embodiment, each lower electrode 5 extends in the left-right direction (second direction) in FIG. Each lower electrode 5 is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example.

  Here, as shown in FIG. 2, the upper electrode 2 has a plurality of first openings (slits) 21 having a shape extending in one direction. Each first opening 21 is formed by partially removing the upper electrode 2. Similarly, the lower electrode 5 has a plurality of second openings (slits) 22 having a shape extending in one direction. Each second opening 22 is formed by partially removing the lower electrode 5. By adopting such an electrode structure, each first opening 21 and each second opening 22 acts as an orientation control element, so that each first opening 21 and each second opening 22 are adjacent to the boundary. Thus, a state (multi-domain alignment) in which the orientation directions of the liquid crystal layer 7 are different in the two regions is obtained. Details of the shapes of the first openings 21 and the second openings 22 will be described later.

  The alignment film 3 is provided on one surface side of the upper substrate 1 so as to cover each upper electrode 2. Similarly, the alignment film 6 is provided on one surface side of the lower substrate 4 so as to cover each lower electrode 5. In the present embodiment, as the alignment film 3 and the alignment film 6, a film (vertical alignment film) that restricts the alignment state in the initial state (when no voltage is applied) of the liquid crystal layer 7 to the vertical alignment state is used.

  The liquid crystal layer 7 is provided between each upper electrode 2 of the upper substrate 1 and each lower electrode 5 of the lower substrate 4. In the present embodiment, the liquid crystal layer 7 is configured using a liquid crystal material (nematic liquid crystal material) having a negative dielectric anisotropy Δε (Δε <0). A thick line 10 illustrated in the liquid crystal layer 7 schematically shows an alignment direction (director) of liquid crystal molecules when a voltage is applied. In the liquid crystal display device of the present embodiment, the alignment state of the liquid crystal molecules in the liquid crystal layer 7 is vertical alignment in the initial state (no voltage applied state), and the alignment state of the liquid crystal molecules so as to intersect the electric field direction by voltage application. Changes.

  The upper polarizing plate 8 is disposed outside the upper substrate 1. The lower polarizing plate 9 is disposed outside the lower substrate 4. The upper polarizing plate 8 and the lower polarizing plate 9 are, for example, in a crossed Nicols arrangement. As shown in FIG. 1, in this embodiment, the absorption axis of the upper polarizing plate 8 is set at an angle of 45 ° from the 3 o'clock to 9 o'clock direction (the extending direction of the lower electrode 5). The absorption axis is set in a direction substantially orthogonal to the absorption axis of the upper polarizing plate 8.

  Next, an example of a manufacturing method of the liquid crystal display device will be described in detail.

  First, a substrate having a transparent electrode on one surface is prepared. As the substrate, for example, a glass substrate with an ITO transparent conductive film having a size of 300 mm × 200 mm, a thickness of 0.7 mm, and a sheet resistance of 30Ω □ can be used. A positive photoresist is applied on one surface of the substrate by a roll coater, and then the photoresist is exposed using a predetermined photomask. As the photomask, a photomask having a predetermined opening pattern formed of a chromium metal film is used. The photomask used here is provided with an opening pattern corresponding to each first opening 21 or each second opening 22.

  After the photomask as described above is brought into close contact with the photoresist surface on the substrate, the opening pattern on the photomask is baked onto the photoresist by irradiating with ultraviolet rays. Next, the photoresist is baked under predetermined conditions (for example, 120 ° C., 10 minutes). The photoresist after baking is subjected to wet development processing using an aqueous KOH solution to remove the portion of the photoresist irradiated with ultraviolet rays. Next, the strength of the resist pattern is improved by further baking the photoresist (for example, 120 ° C. for 30 minutes). The transparent electrode is etched using the resist pattern thus formed as an etching mask. Specifically, for example, wet etching using a mixed aqueous solution of hydrochloric acid and sulfuric acid at 40 ° C. is performed. Finally, the photoresist is completely removed with an aqueous NaOH solution. Thus, the transparent electrode on the substrate is patterned. That is, the upper substrate 1 having a plurality of first openings 21 and the lower substrate 4 having a plurality of second openings 22 are obtained.

  Next, the alignment film 3 is formed on one surface of the upper substrate 1, and the alignment film 6 is formed on one surface of the lower substrate 4. Specifically, the material liquid of the vertical alignment film is pattern-printed on one surface of the upper substrate 1 and one surface of the lower substrate 4, and then baked (for example, 180 ° C. for 30 minutes). Next, a sealing material is formed on one substrate (for example, on one surface of the upper substrate 1). The sealing material is formed, for example, by applying a mixture of silica spacers having a particle size of several μm by a method such as screen printing. A spacer having a particle size of several μm is dispersed on the other substrate (for example, on one surface of the lower substrate 4). The plastic spacer is sprayed by, for example, a dry spraying method. Next, the upper substrate 1 and the lower substrate 4 are bonded to each other so as to face each other, and are fixed by firing in a constant pressure state. Thereafter, a liquid crystal material (with a dielectric anisotropy Δε <0) is injected into the gap between the upper substrate 1 and the lower substrate 4 by a method such as vacuum injection, and the injection port used for the injection is sealed. Later, firing is performed (for example, 120 ° C. for 60 minutes). Thereby, the liquid crystal layer 7 is formed. Thereafter, the first polarizing plate 8 is bonded to the outside of the upper substrate 1, and the second polarizing plate 9 is bonded to the outside of the lower substrate 4. Also, attach a lead frame or the like as appropriate. Thus, the liquid crystal display device is completed.

  Next, the structure of the first opening 21 and the second opening 22 will be described with reference to the schematic plan view shown in FIG. In FIG. 3, a part of each first opening 21 and each second opening 22 when viewed from the upper substrate 1 side is shown in a plan view. In the drawing, each first opening 21 is indicated by a solid line, and each second opening 22 is indicated by a dotted line. In the following, the first opening 21 and the second opening 22 may be collectively referred to simply as “opening”. In FIG. 3, S is the length of each opening in the short direction (short side length), L is the length of each opening in the longitudinal direction (long side length), and Ls is the distance between adjacent openings. (Opening interval), A represents the edge interval between adjacent openings in the short direction.

  As shown in FIG. 3, each first opening 21 is formed in a rectangular shape extending in one direction (the x direction shown in the figure), and is regularly arranged in a checkered pattern in the x direction and the y direction shown in the figure. ing. Similarly, each 2nd opening part 22 is formed in the rectangular shape extended in one direction (x direction of illustration), and is regularly arranged in the checkered pattern in the x direction and y direction of illustration. That is, the first openings 21 and the second openings 22 are arranged with their longitudinal directions aligned in substantially the same direction (the x direction in the figure), and more specifically, the long sides of each are substantially parallel. It is arranged to become. In this example, the longitudinal direction of each opening is arranged in parallel to the horizontal direction of the liquid crystal display device.

As illustrated, in the present embodiment, each first opening 21 and each second opening 22 are provided in a regular checkered pattern. In addition, each first opening 21 and each second opening 22 is between each of the two second openings 22 in which each first opening 21 is adjacent to each other in plan view of each second opening 22. It is arranged relatively so that it may be located in. In other words, the first openings 21 and the second openings 22 are both arranged at a predetermined pitch along each of the x direction and the y direction, and are shifted from each other by a half pitch. Thereby, the distance between the two first openings 21 adjacent in the longitudinal direction and the distance between the two second openings 22 adjacent in the longitudinal direction are both L + Ls × 2. When this is compared with the liquid crystal display device disclosed in Patent Document 2 described above, the distance between adjacent openings can be greatly increased. The mutual distance X between the two closest first openings 21 and the mutual distance X between the two closest second openings 22 can both be expressed as A / cos (tan ⁻¹ Ls / A). At this time, even if Ls = 0, X = A, and the distance can be greatly increased as compared with the liquid crystal display device disclosed in Patent Document 2.

  Next, a description will be given of the results of a simulation analysis of whether a good alignment state can be obtained when a voltage is applied to a liquid crystal display device having each opening as shown in FIG.

  FIG. 4 is a diagram for explaining the condition setting of each opening used in the simulation analysis. 4A shows the structure of the upper electrode 2 provided with the first openings 21, and FIG. 4B shows the structure of the lower electrode 5 provided with the second openings 22. In the drawing, the colored and filled portions are regions where the conductive film exists. The size of each opening was set to L = 0.0736 mm, Ls = 0.0097 mm, A = 0.0288 mm, and S = 0.0097 mm. The layer thickness of the liquid crystal layer 7 was 4 μm, the refractive index anisotropy Δn of the liquid crystal material was about 0.09, the dielectric anisotropy Δε was about −5, and the pretilt angle of the liquid crystal molecules was set to 90 °. The arrangement of the upper polarizing plate 8 and the lower polarizing plate 9 was set as described above. Under such conditions, when the potential of the lower electrode 5 is set to 0 V and the potential of the upper electrode 2 is set to +4 V, the orientation distribution of the liquid crystal molecules in a steady state in which the realignment of the liquid crystal molecules in the liquid crystal layer 7 is stable is simulated. The in-plane transmittance distribution when the liquid crystal display device was observed from the normal direction was evaluated. As for the number of elements at the time of simulation analysis, the in-plane of the liquid crystal display device was set to 60 × 60, and the thickness direction was divided into 30 parts.

  FIG. 5 is a diagram showing a simulation analysis result (in-plane transmittance distribution). In the portion where each opening portion exists, a voltage is not applied between the electrodes, so that it is a dark region. In addition, a cross-shaped dark region is observed in a region corresponding to the space between the first opening 21 and the second opening 22 that are adjacent to each other in the longitudinal direction in plan view and the region above and below the region. This dark region is considered to be a boundary region of alignment domains in which the alignment direction of liquid crystal molecules differs by 180 °, and is considered to be caused by the rotation of the alignment direction of liquid crystal molecules when a voltage is applied. This will be described below.

  FIG. 6 is a diagram showing a director distribution of liquid crystal molecules in the liquid crystal layer. Specifically, FIG. 6A shows the director distribution in the section taken along the line VI-VI ′ shown in FIG. 5, and FIG. 6B shows the section taken along the line VII-VII ′ shown in FIG. The director distribution is shown. In each figure, the vertical direction indicates the layer thickness direction of the liquid crystal layer 7, and the director distribution is indicated by a bar. When attention is paid to the region closer to the upper substrate 1 or the lower substrate 4 than the central portion of the liquid crystal layer 7, it is observed that the tilt direction of the liquid crystal molecules is periodically inverted by 180 ° from the left to the right in the drawing. There is an opening in the upper electrode 2 or the lower electrode 5 at the portion where the director is reversed. The orientation of the liquid crystal molecules is controlled by an oblique electric field between the electrodes generated around each opening, and satisfactory two-domain alignment control can be realized. Comparing each director distribution of FIG. 6A and FIG. 6B, the tilt direction of the liquid crystal molecules is reversed by 180 ° at the same position in the left-right direction, except for the portion where each opening is arranged. You can see that That is, the alignment domains adjacent to each other in the longitudinal direction of each opening are in an alignment state different from the conventional structure in which the alignment directions are reversed by 180 °, and the alignment domains indicating the same alignment direction are arranged in a checkered pattern. I understand.

  Next, a simulation analysis when the distance Ls between adjacent openings is set to 0 will be described. FIG. 7 is a schematic plan view showing the structure of the first opening 21 and the second opening 22 when Ls is set to zero. As shown in the figure, when Ls = 0, each first opening 21 is aligned with one second opening 22 adjacent in the longitudinal direction in plan view and one end in the longitudinal direction of each other. Arranged. That is, the edges (short edge) between the openings overlap. The simulation analysis result (in-plane transmittance distribution) at this time is shown in FIG. The simulation conditions are the same as those described with reference to FIG. 4 except that Ls is set to zero. As shown in the figure, it was found that the area of the dark region at the boundary where the orientation domain is inverted by 180 ° is somewhat reduced.

  Next, a simulation analysis in the case where the distance Ls between adjacent openings is set to a negative value (Ls <0) will be described. FIG. 9 is a schematic plan view showing the structures of the first opening 21 and the second opening 22 when Ls is set to a negative value. As shown in the figure, when Ls <0, each of the first openings 21 has one second opening 22 adjacent in the longitudinal direction in plan view and one end portion in the longitudinal direction of each of the first openings 21. Are arranged in an overlapping manner. The simulation analysis result (in-plane transmittance distribution) at this time is shown in FIG. The simulation conditions are the same as those described with reference to FIG. 4 except that Ls is set to −0.0097 mm (−9.7 μm). As shown in the figure, the area of the dark region at the boundary where the orientation domain is inverted by 180 ° does not change much compared to the case where Ls = 0. In any case, it is considered that the area of the dark region generated at the boundary portion of the alignment domain can be made relatively small if the size of Ls is set to be approximately the same as the length S of each opening in the short direction. It is done.

  Next, a case where a chiral material is added to the liquid crystal layer 7 in order to further increase the transmittance of the dark region in the boundary region where the alignment domain rotates 180 ° will be described. As an example, in the above embodiment in which Ls is set to −0.0097 mm (−9.7 μm), the simulation analysis was performed with the chiral pitch p of the liquid crystal layer 7 set to 10 μm. The simulation analysis result (in-plane transmittance distribution) is shown in FIG. As shown in the figure, it was found that the dark region at the boundary portion of the alignment domain cannot be completely erased, but the transmittance can be further increased. However, when a chiral material is added to the liquid crystal layer 7, the transmittance inside the alignment domain other than the boundary portion of the alignment domain tends to be somewhat lowered. For this, it is desirable to set the layer thickness d of the liquid crystal layer 7 and Δn of the liquid crystal material to be relatively large. In order to increase the transmittance of the dark region, d / p is preferably set to be larger than 0.25, preferably 0.8 or less, particularly 0.74 or less.

  In some of the above-described embodiments, the L, A, and S parameters of each opening are fixed values, but this is not restrictive. S is preferably about 0.005 mm to 0.03 mm, and A is preferably about 0.01 mm to 0.06 mm. Regarding L, the lower limit is preferably larger than A and more preferably larger than 0.04 mm. As the upper limit of L, the pattern shape of the upper electrode 2 or the lower electrode 5, that is, about ½ of the display size is preferable, but about 5 mm or less is considered preferable.

  Next, a further embodiment of the above-described liquid crystal display device will be described.

  In the above-described embodiment, the case where each opening is regularly arranged in a checkered pattern on the entire surface of the effective display portion of the liquid crystal display device has been described. For example, as shown in the schematic plan view shown in FIG. 12, the effective display portion of the liquid crystal display device may be divided into a plurality of regions, and the arrangement parameters of the openings may be set differently in each region. For example, the effective display area is divided into a character display area 51 for displaying “ELECTRIC” and a 5-digit 7-segment display area 52. In the character display area 51, the longitudinal direction of each opening is set to the right (downward to the left). In the 7-segment display area 52, the longitudinal direction of each opening may be set leftward (downwardly right). Further, as shown in FIG. 13, when performing segment display with a relatively large display area, one segment display section is divided into a plurality of areas, and the arrangement parameters of the openings are set differently in each area. May be. In the illustrated example, the heart-shaped character display section is divided into a left area 61 and a right area 62.

  As shown in FIG. 14, when a dot matrix type electrode structure is adopted, the length L in the longitudinal direction of each opening in one pixel unit 11 may be set to be not equal. That is, when each end of the first opening 21 or the second opening 22 is on the edge of the pixel unit 11, the length L in the longitudinal direction may be shortened. However, it is preferable that the position of the short side where the adjacent openings exist is substantially on a straight line in the short side direction. In this case, the boundary region of the alignment domain extends in the right upward direction (left downward direction), but the long side of each opening arranged in this region extends in the left upward direction (right downward direction). It can be seen that they are arranged almost along the existing straight line.

  FIG. 15 is a diagram showing an image obtained by actually manufacturing a liquid crystal display device having each opening having the structure shown in FIG. 14 and observing one pixel portion 11 with a reflection microscope. As described above, the belt-like upper electrode 2 is provided in the vertical direction of the liquid crystal display device, and the belt-like lower electrode 5 is provided in the left-right direction (see FIG. 1). Then, each opening for realizing checkered two-domain alignment control rotated approximately 45 ° clockwise with respect to the 9 o'clock direction of the liquid crystal display device and approximately 45 ° clockwise with respect to the 3 o'clock direction is provided on the upper side. The electrode 2 and the lower electrode 5 were provided. One pixel portion shown in the figure is 0.45 mm square, and the interval between adjacent pixel portions 11 is 0.03 mm. The pixel portion 11 is divided into two in the diagonal direction, and the openings are arranged in a checkered pattern in each of the upper electrode 2 and the lower electrode 5. Regarding the parameters of each opening, S is approximately 0.007 mm, A is approximately 0.03 mm, and Ls is approximately 0.007 mm. About each absorption axis of the upper side polarizing plate 8 and the lower side polarizing plate 9, an optical axis was arrange | positioned at about 45 degrees with respect to the longitudinal direction of each opening part. That is, the lower polarizing plate 9 is arranged in the horizontal direction of the pixel portion 11, and the upper polarizing plate 8 is arranged in the vertical direction of the pixel portion 11. A liquid crystal material having a Δn of 0.15 was used, and the thickness of the liquid crystal layer 7 was approximately 3.8 μm.

  FIG. 16A is a diagram showing a polarization microscope observation image of the pixel portion 11 when a voltage is applied when the liquid crystal display device shown in FIG. 15 is manufactured using a liquid crystal material to which no chiral material is added. In this observation image, the polarizing plate arrangement of the liquid crystal display device is such that the upper polarizing plate (first polarizing plate) 8 has an absorption axis of 9 o'clock to 3 o'clock and the lower polarizing plate (second polarizing plate) 9 has an absorption axis. It was set at 6 o'clock to 12 o'clock. It can be seen that the dark region is not observed except for the boundary region of the alignment domain and the vicinity of the edge of the pixel portion 11, and a good alignment state is obtained. It was confirmed by appearance observation that uniform and good two-domain alignment control was realized. From this, it is considered that the orientation domains are arranged in a checkered pattern as in the case of the simulation analysis described above. On the other hand, a dark region is observed in the boundary region of the alignment domain, but its area is relatively small and the alignment pattern is relatively uniform. Similar dark region patterns were observed for the other pixel portions 11.

  FIG. 16B shows a pixel portion 11 when a voltage is applied when the liquid crystal display device shown in FIG. 15 is manufactured using a liquid crystal material to which a chiral material is added so that d / p is approximately 0.6. It is a figure which shows the polarizing microscope observation image. As in the case of FIG. 16A, each alignment domain has a very uniform alignment state, and the transmittance is increased at the boundary portion of the alignment domain as compared with the case where no chiral material is added. Was confirmed.

  In the above description, the case where the long side orientations of adjacent openings are on substantially the same straight line has been studied. However, there may be a case where positional deviation occurs during actual manufacturing. Therefore, the orientation texture was observed even when the long side orientations of adjacent openings were not on the same straight line. The polarization microscope observation image is shown in FIG. In this example, the opening disposed obliquely on the upper left side and the opening disposed on the obliquely lower right side adjacent to the opening are displaced by an amount equal to the short side of each opening. As shown in the figure, the regularity of the pattern is relatively maintained in the boundary region of the alignment domains, and it was confirmed that the two-domain alignment control was realized in appearance. However, when the viewing angle characteristic is actually observed, a slight deformation is recognized in the isoluminance curve when a voltage is applied. The permissible value of the displacement of the opening varies depending on the distance A. A is optimally about 0.02 to 0.06. Therefore, it is considered that the displacement of the openings is allowed to occur below this range.

  FIG. 17 is a diagram for explaining an embodiment in which the shape of each opening is changed. As shown in FIG. 17A, the first openings 21a provided in the upper electrode 2 are formed in a rectangular shape extending in one direction, and are regularly arranged in a checkered pattern. Each first opening portion 21a has a longitudinal side (outer edge) and a short side (outer edge) obliquely intersecting at an angle other than 90 °, and this point is the first in each embodiment described above. It is different from the opening 21. Further, as shown in FIG. 17B, the second openings 22a provided in the lower electrode 5 are formed in a rectangular shape extending in one direction, and are regularly arranged in a checkered pattern. Each of the second openings 22a has a longitudinal side (outer edge) and a lateral side (outer edge) obliquely intersecting at an angle other than 90 °, and this point is the second in each embodiment described above. It is different from the opening 22. By adopting such a structure, the boundary region of the alignment domain can be controlled in substantially the same direction as the short side of each opening. In FIG. 17, the first openings 21a and the second openings 22a are substantially parallel in their short sides and are substantially in a straight line. Moreover, the 1st opening part 21a and the 2nd opening part 22a which adjoin a longitudinal direction in planar view are arrange | positioned by aligning the one end part of a mutual longitudinal direction.

  FIG. 18 is a diagram showing a simulation analysis result of the liquid crystal display device having each opening having the structure shown in FIG. For each parameter, A was 0.032 mm, S was 0.009 mm, and L was 0.113 mm as illustrated. Other calculation conditions are the same as those of the above-described embodiments. FIG. 18A shows a transmittance distribution when the liquid crystal display device is observed from the normal direction. In each analysis result, the polarizing plate arrangement of the liquid crystal display device is such that the upper polarizing plate (first polarizing plate) 8 has an absorption axis of 9 o'clock to 3 o'clock and the lower polarizing plate (second polarizing plate) 9 has an absorption axis. It was set at 6 o'clock to 12 o'clock. Good alignment uniformity is obtained for the alignment domains existing between the openings. In addition, although the boundary region of the alignment domain is slightly wavy, a dark region is generated substantially along the vertical direction, and since the pattern is regular, it is considered that there is no display defect in appearance. . From this result, it was confirmed that the direction of the boundary portion of the alignment domain can be controlled by the direction of the side in the short direction of each opening. FIG. 18B shows a transmittance distribution when a liquid crystal display device in which the liquid crystal layer 7 is formed using a liquid crystal material added with a chiral material so that the chiral pitch p is 10 μm is observed from the normal direction. It was confirmed that the transmittance of the dark region at the boundary portion of the alignment domain can be increased by adding the chiral material.

  In this simulation analysis, the boundary part of the alignment domain is arranged in the vertical direction. However, the boundary part of the alignment domain can be changed in the horizontal direction by rotating the arrangement of the openings 90 degrees counterclockwise. Is clear. Furthermore, it is also clear that the extending direction of the boundary part of the alignment domain can be arbitrarily set by changing the angle formed between the outer edge in the short direction and the outer edge in the longitudinal direction of each opening existing in the boundary part of the alignment domain. It is. The boundary part of the alignment domain may be visually recognized, but the boundary part is controlled in the horizontal direction and the vertical direction of the liquid crystal display device, for example, by using the above structure, so that the appearance is not conspicuous. Is possible.

  According to the present embodiment as described above, the distance between adjacent openings can be greatly increased in each of the upper electrode and the lower electrode. Thereby, an increase in resistance value and disconnection of the electrodes due to the coupling between the openings can be avoided, and a decrease in display quality can be avoided.

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously. For example, in the above-described embodiment, the first opening and the second opening are approximately the same size, but the sizes may be different. In addition, the relative relationship between the longitudinal direction of each first opening and each second opening and the horizontal direction of the liquid crystal display device can be arbitrarily set. In each of the above embodiments, a liquid crystal display device having a vertical alignment type liquid crystal layer has been described. However, the alignment state of the liquid crystal layer is not limited to this, and a horizontal alignment mode having a pretilt angle close to 0 °, for example, ECB In the mode, the TN mode, and the STN mode, the two-domain orientation control similar to the above can be performed.

  DESCRIPTION OF SYMBOLS 1 ... Upper side substrate (1st board | substrate) 2 ... Upper side electrode (1st electrode) 3 ... Alignment film 4 ... Lower side substrate (2nd board | substrate) 5 ... Lower side electrode (2nd electrode) 6 ... Alignment film 7 ... Liquid crystal layer DESCRIPTION OF SYMBOLS 8 ... Upper side polarizing plate (1st polarizing plate) 9 ... Lower side polarizing plate (2nd polarizing plate) 11 ... Pixel part 21 ... 1st opening part 22 ... 2nd opening part 51 ... Character display area 52 ... 7 segment display area 61: Left area of character display section 62 ... Right area of character display section

Claims (4)

A first substrate having a first electrode on one side;
A second substrate having a second electrode on one side, the second substrate being disposed opposite to the first substrate so that the second electrode and the first electrode of the first substrate face each other;
A vertically aligned liquid crystal layer provided between the first substrate and the second substrate;
It is arrange | positioned on the outer side of each of the said 1st board | substrate and the said 2nd board | substrate, mutual mutual absorption axis is substantially orthogonal, and each said absorption axis makes the angle of about 45 degrees with respect to a 1st direction, respectively. A pair of polarizing plates arranged;
Including
Each of the first electrodes has a shape extending in the first direction, and has a plurality of first openings provided in a regular checkered pattern,
Each of the second electrodes has a shape extending in the first direction, and has a plurality of second openings provided in a regular checkered pattern,
Each of the plurality of first openings is adjacent to the second direction in a plan view of the plurality of second openings in both the first direction and the second direction orthogonal to the first direction. The plurality of first openings and the plurality of second openings are relatively disposed so as to be positioned between
Each of the plurality of first openings and the plurality of second openings is arranged so as to partially overlap each one end side adjacent to the first direction in plan view,
Each of the plurality of first openings and the plurality of second openings has a length in the second direction of not less than 0.007 mm and not more than 0.03 mm.
When a voltage is applied between the first electrode and the second electrode, each region corresponding to the position where the plurality of first openings and the plurality of second openings exist in the liquid crystal layer No voltage is applied, and each region is observed as a dark region when viewed from the outside of either of the pair of polarizing plates.
Liquid crystal display device.   A substantially rectangular pixel portion is defined by a region where the first electrode and the second electrode overlap in a plan view,
  The plurality of first openings and the plurality of second openings are arranged such that each other end is overlapped with an edge portion of the pixel region in plan view, and each longitudinal direction of each of the pixel portions is Arranged at an angle other than perpendicular to the extending direction of the edge portion,
  The liquid crystal display device according to claim 1.   One display portion is defined for each region where the first electrode and the second electrode overlap in plan view,
  The inside of the one display section is divided into a plurality of areas, and the first direction for defining the arrangement of each of the plurality of first openings and the plurality of second openings for each of the divided areas Are set in different directions,
  The liquid crystal display device according to claim 1.   An effective display area defined in an overlapping area of the first substrate and the second substrate is divided into a plurality of areas, and the plurality of first openings and the plurality of first areas are divided into the divided areas. The first direction for defining the arrangement of each of the two openings is set in a different direction,
  The liquid crystal display device according to claim 1.