JP2011112952A - Liquid crystal display element and optical compensation method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element having a wide angle of view and to provide an optical compensation method thereof. <P>SOLUTION: Two substrates opposed to each other in a liquid crystal cell 1 are subjected to alignment treatment in directions orthogonal to each other. A front side polarizing plate 2 is disposed on a viewer side of the liquid crystal cell 1 in such a way that transmission axis 2a of the polarizing plate 2 and a direction 16a of alignment treatment performed on the viewer side substrate of the liquid crystal cell 1 form an angle of 45° and a rear side polarizing plate 3 is disposed on the side opposite to the viewer side of the liquid crystal cell 1 in such a way that transmission axis 3a of the polarizing plate 3 and a direction 19a of alignment treatment performed on the substrate opposite to the viewer side substrate of the liquid crystal cell 1 form an angle of 45°. Angle-of-view compensation films 4 and 5 are disposed between the liquid crystal cell 1 and the front side polarizing plate 2 and between the liquid crystal cell 1 and the rear side polarizing plate 3 respectively in such a way that optical axes 4a and 5a of the films 4 and 5 are made coincident with the alignment treatment directions 16a and 19a, respectively. A retardation plate 9 is disposed between the rear side polarizing plate 3 and the rear side angle-of-view compensation film 5 in such a way that the slow axis 9a of the retardation plate is made coincident with the transmission axis 3a thereof. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element, and more particularly to a liquid crystal display element having a liquid crystal layer in which liquid crystal molecules are twist-aligned at an angle of 90 ° and an optical compensation method thereof.

  In general, there is known a liquid crystal display element having a liquid crystal layer sandwiched between substrates having a pair of planar electrodes and liquid crystal molecules in the liquid crystal layer being twist-oriented from one substrate to the other substrate. . In a twisted nematic (TN) type liquid crystal display element which is one of such liquid crystal display elements, the liquid crystal molecules in the liquid crystal layer are twist-aligned at an angle of 90 °. In the TN type liquid crystal display element, polarizing plates are disposed on the front side which is the observation side of the liquid crystal layer and on the rear side on the opposite side. The pair of polarizing plates are arranged with their transmission axes orthogonal to each other. Further, a backlight, which is a light source, is disposed on the rear side of the rear polarizing plate. In the liquid crystal display device having such a configuration, the orientation of the liquid crystal molecules in the liquid crystal layer can be controlled by a voltage applied to the planar electrodes sandwiching the liquid crystal layer. By controlling the orientation of the liquid crystal molecules, the amount of light transmitted through the two polarizing plates among the light emitted from the backlight is controlled, and the liquid crystal display element displays an image.

  In the liquid crystal display device as described above, the behavior of the liquid crystal molecules in the vicinity of the alignment film provided on the substrate in order to regulate the alignment of the liquid crystal molecules is suppressed by the strong alignment regulating force by the alignment film (so-called Anchoring effect). For example, such an anchoring effect causes a decrease in contrast of the liquid crystal display element, gradation inversion at an intermediate gradation, and the like. As a result, the display quality of the liquid crystal display element is degraded.

  For such deterioration in display quality, the orientation of the orientation film in the orientation film, the orientation of the transmission axis of the polarizing plate, the insertion of various optical films between the liquid crystal cell and the front and rear polarizing plates, and the insertion For example, Patent Document 1 discloses a technique for optimizing the orientation of the optical axis of various optical films to improve display quality. In Patent Document 1, for example, the alignment treatment direction in the alignment film and the direction of the transmission axis of the polarizing plate are arranged to intersect at an angle of 45 °, or between the liquid crystal cell and the front and rear polarizing plates. A technique for inserting a pair of viewing angle compensation films made of a discotic liquid crystal layer is disclosed.

JP 2006-285220 A

  With the technology disclosed in Patent Document 1, the display quality of the liquid crystal display element described in Patent Document 1 is improved. However, there still remains a problem that an observation angle range in which the display of the liquid crystal display element can be observed with good contrast, that is, a viewing angle becomes narrower in a specific direction than in other directions.

  Therefore, an object of the present invention is to provide a liquid crystal display element having a good display quality with improved viewing angles in all directions and a method for designing such a liquid crystal display element.

  In order to achieve the above object, one embodiment of the liquid crystal display element of the present invention includes a front substrate and a rear substrate in which orientation treatments are performed in directions of 90 ° on the surfaces facing each other on which electrodes are formed, and A liquid crystal element having a liquid crystal layer provided by twist-aligning liquid crystal molecules at a twist angle of 90 ° between the front substrate and the rear substrate; and the liquid crystal layer side opposite to the front substrate, A front polarizing plate arranged so that a transmission axis forms an angle of 45 ° with respect to the direction of alignment treatment of the front substrate, and the front polarizing plate on the side opposite to the liquid crystal layer side with respect to the rear substrate. A rear polarizing plate disposed so that the transmission axis forms an angle of 90 ° with respect to the transmission axis, and a front optical anisotropic film disposed between the liquid crystal element and the front polarizing plate, Specific to the normal of the film surface of the front optical anisotropic film A negative optical anisotropy in which the refractive index in the direction inclined in the direction is minimum, and a direction in which the specific direction in which the refractive index is minimum is projected onto the film surface and the alignment processing direction of the front substrate are formed An angle of 0 ° is a front optical anisotropic film, and a rear optical anisotropic film disposed between the liquid crystal element and the rear polarizing plate, the rear optical anisotropic film A negative optical anisotropy having a minimum refractive index in a direction inclined in a specific direction with respect to the normal of the film surface, and a direction in which the specific direction with the minimum refractive index is projected onto the film surface and The angle formed by the alignment treatment direction of the rear substrate is 0 °, the rear optical anisotropic film, and the retardation plate disposed between the rear polarizing plate and the rear optical anisotropic film A direction in which the refractive index is greatest along the plate surface of the retardation plate, and a refractive index which is the largest along the plate surface. The direction perpendicular to the direction and the normal direction of the plate surface are defined as s1, f1, and z1, respectively, and the refractive indexes in the directions of the s1, f1, and z1 axes are ns1, nf1, respectively. And nz1, a retardation plate having a relationship of ns1> nf1 = nz1 and an angle formed by the s1 axis and the transmission axis of the rear polarizing plate is 0 °. Features.

  Another embodiment of the liquid crystal display element of the present invention includes a front substrate and a rear substrate in which orientation treatments are performed in directions of 90 ° with each other on surfaces facing each other, and the front side A liquid crystal element having a liquid crystal layer provided by twist-aligning liquid crystal molecules at a twist angle of 90 ° between the substrate and the rear substrate; and the front substrate on a side opposite to the liquid crystal layer side with respect to the front substrate A front polarizing plate disposed so that a transmission axis forms an angle of 45 ° with respect to the orientation treatment direction, and a transmission axis of the front polarizing plate on a side opposite to the liquid crystal layer side with respect to the rear substrate. A rear polarizing plate arranged so that the transmission axis forms an angle of 90 °, and a front optically anisotropic film arranged between the liquid crystal element and the front polarizing plate, the front side Inclined in a specific direction with respect to the normal of the film surface of the optically anisotropic film The angle formed between the direction in which the specific direction in which the refractive index is minimized and the specific direction in which the refractive index is minimized is projected onto the film surface and the orientation processing direction of the front substrate is 0 °. A rear optical anisotropic film disposed between the front optical anisotropic film and the liquid crystal element and the rear polarizing plate, wherein the film surface of the rear optical anisotropic film A negative optical anisotropy having a minimum refractive index in a direction tilted in a specific direction with respect to the normal, and a direction in which the specific direction with the minimum refractive index is projected onto the film surface and the rear substrate; An angle formed with the orientation treatment direction is 0 °, and is a first optical retardation film disposed between a rear optical anisotropic film, the front polarizing plate and the front optical anisotropic film. A direction in which the refractive index is greatest along the plate surface of the first retardation plate, and a refractive index which is the largest along the plate surface. The direction perpendicular to the direction and the normal direction of the plate surface are defined as s1, f1, and z1, respectively, and the refractive indexes in the directions of the s1, f1, and z1 axes are ns1, nf1, respectively. , And nz1, the relationship is ns1> nf1 = nz1, and the angle formed between the s1 axis of the first retardation plate and the optical axis of the front optical anisotropic film is 0 °. 1 is a second retardation plate disposed between the retardation plate 1 and the rear polarizing plate and the rear optically anisotropic film, along the plate surface of the second retardation plate The direction having the highest refractive index, the direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are defined as the s2 axis, the f2 axis, and the z2 axis, respectively. When the refractive indexes in the directions of the f2 axis and the z2 axis are ns2, nf2, and nz2, respectively. , Ns2> nf2 = nz2, and the angle between the s2 axis of the second retardation plate and the optical axis of the rear optical anisotropic film is 0 °. And a third retardation plate disposed between the rear polarizing plate and the second retardation plate, and having the highest refractive index along the plate surface of the third retardation plate The direction perpendicular to the direction with the highest refractive index along the plate surface, and the normal direction of the plate surface are the s3 axis, the f3 axis, and the z3 axis, respectively, and the s3 axis, the f3 axis, and the When the refractive indexes in the direction of the z3 axis are ns3, nf3, and nz3, respectively, the relationship is ns3> nf3 = nz3, and the s3 axis of the third retardation plate and the transmission axis of the rear polarizing plate And a third retardation plate having an angle of 0 °.

  Further, according to one aspect of the optical compensation method of the liquid crystal display element of the present invention, a front substrate and a rear substrate in which alignment treatments are performed in directions of 90 ° with each other on surfaces facing each other, and A liquid crystal element having a liquid crystal layer provided by twist-aligning liquid crystal molecules at a twist angle of 90 ° between the front substrate and the rear substrate, and disposed on a side opposite to the liquid crystal layer side with respect to the front substrate; A front polarizing plate, and a rear polarizing plate disposed on the opposite side of the liquid crystal layer with respect to the rear substrate so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate Determining the angle between the direction of the alignment treatment of the front substrate of the liquid crystal element and the transmission axis of the front polarizing plate, and being disposed between the liquid crystal element and the front polarizing plate. Negative with a minimum refractive index in a direction inclined to a specific direction. The refractive index in the direction inclined in a specific direction with respect to the normal of the film surface, which is arranged between the front optical anisotropic film having optical anisotropy, the liquid crystal element and the rear polarizing plate And the rear optical anisotropic film having negative optical anisotropy, the orientation treatment direction of the front substrate and the direction in which the refractive index of the front optical anisotropic film is minimized An angle formed by the direction projected on the film surface of the conductive film, an orientation treatment direction of the rear substrate, and a direction in which the refractive index of the rear optical anisotropic film is minimized. And the angle formed with the direction projected onto the film surface of the liquid crystal display element when the sufficiently strong electric field is formed between the front substrate and the rear substrate is the minimum value of luminance displayed on the liquid crystal display element The front polarizing plate and the front optical The most refractive index along the plate surface of the retardation plate in the retardation plate disposed between the isotropic film and at least one of the rear polarizing plate and the rear optical anisotropic film. , The direction perpendicular to the direction with the highest refractive index along the plate surface, and the normal direction of the plate surface are the s-axis, f-axis, and z-axis, respectively, and the s-axis, the f-axis, And the refractive index in the direction of the z-axis is ns, nf, and nz, respectively, the angle formed by the transmission axis of the rear polarizing plate and the s-axis of the retardation plate, and ns, nf, nz, and In combination with the thickness of the retardation plate, the maximum value of the brightness displayed on the liquid crystal display element when a sufficiently strong electric field is formed between the front substrate and the rear substrate is minimized. It is characterized in that it is determined in the same way.

  Further, another aspect of the optical compensation method for the liquid crystal display element of the present invention is that the front substrate and the rear substrate in which the surfaces opposite to each other on which the electrodes are formed are subjected to alignment treatment in a direction of 90 ° with each other. A liquid crystal element having a liquid crystal layer in which liquid crystal molecules are twist-aligned at a twist angle of 90 ° between the front substrate and the rear substrate, and on the opposite side of the liquid crystal layer side with respect to the front substrate A front polarizing plate disposed and a rear polarizing plate disposed on the opposite side of the liquid crystal layer with respect to the rear substrate so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate. And an angle formed between a direction of alignment treatment of the front substrate of the liquid crystal element and a transmission axis of the front polarizing plate in a plate, and the film surface disposed between the liquid crystal element and the front polarizing plate The refractive index in a direction inclined in a specific direction with respect to the normal of A refractive index in a direction inclined in a specific direction with respect to the normal of the film surface, which is disposed between the front optical anisotropic film having negative optical anisotropy, the liquid crystal element, and the rear polarizing plate. In the rear optical anisotropic film having the negative optical anisotropy that minimizes the orientation of the front substrate and the direction in which the refractive index of the front optical anisotropic film is minimized. An angle formed by the direction projected on the film surface of the anisotropic film, an orientation treatment direction of the rear substrate, and a direction in which the refractive index of the rear optical anisotropic film is minimized are the rear optical anisotropic. The angle formed with the direction projected on the film surface of the conductive film, and the maximum value of the luminance displayed on the liquid crystal display element when a sufficiently strong electric field is formed between the front substrate and the rear substrate Is determined to be the smallest, the front polarizing plate and the front side A first retardation plate disposed between the optically anisotropic film and a second retardation plate disposed between the rear polarizing plate and the rear optical anisotropic film, The direction having the highest refractive index along the plate surface of the first retardation plate, the direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s1 axis, The refractive indices in the directions of the s1 axis, the f1 axis, and the z1 axis are ns1, nf1, and nz1, respectively, and are most refracted along the plate surface of the second phase difference plate. The direction in which the refractive index is large, the direction orthogonal to the direction having the largest refractive index along the plate surface, and the normal direction of the plate surface are the s2 axis, the f2 axis, and the z2 axis, respectively. , And the refractive index in the z2 axis direction are ns2, nf2, and nz2, respectively. The angle formed by the transmission axis of the front polarizing plate and the s1 axis of the first retardation plate, ns1, nf1, nz1 of the first retardation plate, and the thickness of the first retardation plate d1 and the angle formed by the transmission axis of the front polarizer and the s2 axis of the second retardation plate, ns2, nf2, nz2 and the second position of the second retardation plate. The combination with the thickness d2 of the phase difference plate is determined so that the minimum value of luminance displayed on the liquid crystal display element when an electric field is not formed between the front substrate and the rear substrate is maximized. And the phase difference in the phase difference plate disposed between at least one of the front side polarization plate and the first phase difference plate and between the rear side polarization plate and the second phase difference plate. The direction with the highest refractive index along the plate surface of the plate, the direction orthogonal to the direction with the highest refractive index along the plate surface , And the normal direction of the plate surface are s-axis, f-axis, and z-axis, respectively, and the refractive indices in the directions of the s-axis, f-axis, and z-axis are ns, nf, and nz, respectively. A combination of an angle formed by the transmission axis of the rear polarizing plate and the s-axis of the retardation plate, and ns, nf, nz, and the thickness of the retardation plate, the front substrate and the rear substrate. The maximum luminance value displayed on the liquid crystal display element when a sufficiently strong electric field is formed between them is determined to be minimum.

  According to the present invention, it is possible to provide a liquid crystal display element having good display quality with improved viewing angles in all directions and a method for designing such a liquid crystal display element.

1 is a schematic cross-sectional view of a liquid crystal display element according to a first embodiment of the present invention. 1 is an exploded plan view showing an optical configuration of a liquid crystal display element according to a first embodiment of the present invention. 1 is a schematic cross-sectional view of a front viewing angle compensation film according to a first embodiment of the present invention. It is a figure explaining the orientation state of the liquid crystal molecule in case the electric field is not formed in the liquid crystal display element which concerns on the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing. It is a figure explaining the orientation state of a liquid crystal molecule in case the electric field is formed in the liquid crystal display element which concerns on the 1st Embodiment of this invention, (a) is a top view, (b) is sectional drawing. The figure which shows the viewing angle characteristic of the said liquid crystal display element in case the black phase difference plate does not exist in the liquid crystal display element which concerns on the 1st Embodiment of this invention. In the liquid crystal display device according to the first embodiment of the present invention, when the slow axis of the black compensation phase difference plate 9 is orthogonal to the transmission axis of the rear polarizing plate, R0 and light of the black compensation phase difference plate The figure which shows the relationship with the maximum value Tmax of a leak. In the liquid crystal display device according to the first embodiment of the present invention, when the slow axis of the black compensation retardation plate 9 is parallel to the transmission axis of the rear polarizing plate, R0 and light of the black compensation retardation plate The figure which shows the relationship with the maximum value Tmax of a leak. The figure which shows the viewing angle characteristic of the liquid crystal display element which concerns on the 1st Embodiment of this invention. The typical sectional view of the liquid crystal display element concerning a 2nd embodiment of the present invention. The disassembled plan view which shows the optical structure of the liquid crystal display element which concerns on the 2nd Embodiment of this invention. The figure which shows the viewing angle characteristic of the said liquid crystal display element in case the retardation plate for black compensation does not exist in the liquid crystal display element which concerns on the 2nd Embodiment of this invention. In the liquid crystal display device according to the second embodiment of the present invention, when the slow axis of the black compensation retardation plate is orthogonal to the transmission axis of the rear polarizing plate, R0 of the black compensation retardation plate and light leakage The figure which shows the relationship with the maximum value Tmax. In the liquid crystal display device according to the second embodiment of the present invention, R0 and light leakage of the black compensation phase difference plate when the slow axis of the black compensation phase difference plate is parallel to the transmission axis of the rear polarizing plate. The figure which shows the relationship with the maximum value Tmax. The figure which shows the viewing angle characteristic of the liquid crystal display element which concerns on the 2nd Embodiment of this invention.

[First Embodiment]
First, a first embodiment of the present invention will be described with reference to the drawings. As shown schematically in FIG. 1, the liquid crystal display device according to the first embodiment of the present invention includes a liquid crystal cell 1, a front polarizing plate 2, a rear polarizing plate 3, and a front viewing angle compensation film 4. The rear viewing angle compensation film 5 and the black compensation phase difference plate 9 are provided. The front polarizing plate 2 and the rear polarizing plate 3 are arranged so that their light transmission axes are orthogonal to each other. The liquid crystal cell 1 sandwiched between these two polarizing plates is, for example, a twisted nematic liquid crystal cell and functions as a liquid crystal shutter. The alignment directions of the front horizontal alignment film 16 and the rear horizontal alignment film 19 of the liquid crystal cell 1 are orthogonal to each other, respectively, the direction in which the transmission axis of the front polarizing plate 2 is rotated by 45 °, and the rear polarizing plate 3 This is the direction in which the transmission axis is rotated by 45 °.

  A backlight, which is a light source (not shown), is disposed on the rear side of the rear polarizing plate 3 (on the opposite side to the observation side, which is the lower side in the drawing). By forming an electric field between the common electrode 15 and the pixel electrode 17 that sandwich the liquid crystal layer 110 of the liquid crystal cell 1, it is possible to control the amount of light transmitted through the two polarizing plates out of the light emitted from the backlight. In this way, the liquid crystal display element displays an image.

  The front viewing angle compensation film 4 between the liquid crystal cell 1 and the front polarizing plate 2 and the rear viewing angle compensation film 5 between the liquid crystal cell 1 and the rear polarizing plate 3 include discotic liquid crystals. . The discotic liquid crystal has a hybrid orientation that gradually rises from a lying orientation state from one surface to the other surface. By using such a viewing angle compensation film, birefringence in various angular directions can be compensated. That is, the viewing angle compensation film has an effect of compensating the black display and expanding the observation angle range in which the display of the liquid crystal display element can be observed with good contrast, that is, the viewing angle. In this embodiment, the film surface projection direction of the average direction of the molecular axis 43b of the discotic liquid crystal molecules 43a of the front viewing angle compensation film 4 coincides with the orientation direction of the front horizontal alignment film 16, and the rear viewing angle compensation is performed. The film surface projection direction of the average direction of the molecular axis 53 b of the discotic liquid crystal molecules 53 a of the film 5 coincides with the alignment direction of the rear horizontal alignment film 19.

  Furthermore, the liquid crystal display element according to the present embodiment includes a black compensation phase difference plate 9 between the rear viewing angle compensation film 5 and the rear polarizing plate 3. The black compensation phase difference plate 9 is a uniaxial film, and the slow axis of the black compensation phase difference plate is parallel to the transmission axis of the rear polarizing plate 3.

  Due to the presence of the black compensation phase difference plate 9 as described above, it is possible to further reduce light leakage during black display in a direction in which the transmission axes of the front polarizing plate 2 and the rear polarizing plate 3 are rotated by 45 °. . In other words, the presence of the black compensation phase difference plate 9 further improves the viewing angle during black display compared to the case without this.

  In designing the liquid crystal display device according to the present embodiment, first, while confirming the quality of the viewing angle characteristics, the alignment direction of the front horizontal alignment film 16 and the rear horizontal alignment film 19 of the liquid crystal cell 1 and the front polarization The positional relationship between the transmission axes of the plate 2 and the rear polarizing plate 3 is determined. Next, in order to improve the viewing angle characteristics of the liquid crystal display element composed of the liquid crystal cell 1, the front polarizing plate 2, and the rear polarizing plate 3, the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 Consider insertion. Again, the positional relationship between these optical axes is determined while checking the viewing angle characteristics. Then, in order to further improve the viewing angle characteristics, the insertion of the black compensation phase difference plate 9 will be examined. Again, the positional relationship between these optical axes is determined while checking the viewing angle characteristics.

[First embodiment]
Next, an example of the liquid crystal display element according to the first embodiment will be specifically described with reference to the drawings. This liquid crystal display element is an active matrix type liquid crystal display element. As shown in FIG. 1, the liquid crystal display element includes, in order from the viewing side of the liquid crystal display element, a front polarizing plate 2, a front viewing angle compensation film 4, a liquid crystal cell 1, a rear viewing angle compensation film 5, and a black compensation device. A retardation plate 9 and a rear polarizing plate 3 are provided.

  In the liquid crystal cell 1, as shown in FIG. 1, a front glass substrate 11 and a rear glass substrate 12 are bonded together with a frame-shaped sealing material (not shown) with a predetermined gap. On the opposite surface of the front glass substrate 11, a black mask 13 having openings corresponding to the respective pixel regions is disposed. A red color filter 14R, a green color filter 14G, and a blue color filter 14B are arranged in a predetermined arrangement on the surface facing the rear glass substrate 12 of the front glass substrate 11 so as to correspond to the openings formed by the black mask 13. It is installed in each. These color filters have an area larger than the opening by an appropriate length, and the peripheral edge thereof overlaps a part of the black mask 13. The thicknesses of the red color filter 14R, the green color filter 14G, and the blue color filter 14B are the thicknesses of the liquid crystal layer 110 set for each pixel region in which each color filter is arranged, that is, the red pixel liquid crystal layer thickness dr, green It is determined by the relationship between the pixel liquid crystal layer thickness dg and the blue pixel liquid crystal layer thickness db. This optimization of the liquid crystal layer thickness will be described later.

  On the surfaces of the red color filter 14R, the green color filter 14G, and the blue color filter 14B, a common electrode 15 made of a single film-like transparent conductive film is attached so as to cover them. A front horizontal alignment film 16 is deposited so as to cover the common electrode 15. A rubbing process is performed on the surface of the front horizontal alignment film 16 to form grooves in a certain direction.

  A plurality of pixel electrodes 17 made of a transparent conductive film are arranged in a matrix on the opposing surface of the rear glass substrate 12 so as to correspond to the openings formed by the black mask 13. A thin film transistor 18 as a switching element is connected to each pixel electrode 17. Further, a rear horizontal alignment film 19 is uniformly applied so as to cover all the pixel electrodes 17 and the thin film transistors 18 and the like. The surface of the rear horizontal alignment film 19 is also rubbed in the same manner as the surface of the front horizontal alignment film 16, and grooves in a certain direction are carved. Note that the direction of the grooves of the front horizontal alignment film 16 and the direction of the grooves of the rear horizontal alignment film 19 are in a relationship of twist positions forming an angle of 90 °.

  A liquid crystal layer 110 is formed in the gap between the front horizontal alignment film 16 and the rear horizontal alignment film 19. In the liquid crystal layer 110, nematic liquid crystal molecules having positive dielectric anisotropy are encapsulated. In the state where no electric field is formed between the pixel electrode 17 and the common electrode 15, the liquid crystal molecules are in the vicinity of the front horizontal alignment film 16 and the rear horizontal alignment film 19, respectively. And the direction of the rear horizontal alignment film 19 along the direction of the grooves are arranged in response to the alignment regulating force. Accordingly, the liquid crystal molecules in the liquid crystal layer 110 are twisted between the front horizontal alignment film 16 and the rear horizontal alignment film 19.

In a state where no electric field is formed between the pixel electrode 17 and the common electrode 15, the present liquid crystal display element performs white display. In order to maximize the light transmittance for this white display, it is the product of the refractive index anisotropy Δn of the liquid crystal molecules and the liquid crystal layer thickness d, and is an amount indicating the optical path difference between ordinary light and extraordinary light. The retardation Δn · d needs to be a specific value. Here, the liquid crystal layer 110 has different refractive index anisotropy Δn depending on the wavelength of transmitted light. Therefore, in order for the liquid crystal display device to realize high color reproducibility, it is necessary to consider the wavelength dependence of the refractive index anisotropy Δn. Therefore, in the present liquid crystal display element, the thickness of the liquid crystal layer is set so that a birefringence of λ / 2 is given to each wavelength λ of red light, green light, and blue light transmitted through the liquid crystal layer 110. Is set. In the liquid crystal cell 1 of the present embodiment, the red pixel liquid crystal layer thickness dr, the green pixel liquid crystal layer thickness dg, and the blue pixel liquid crystal layer thickness db cancel the wavelength dependence of the refractive index anisotropy Δn with respect to each wavelength light. The refractive index anisotropy Δnb for blue wavelength light, the refractive index anisotropy Δng for green wavelength light, and the refractive index anisotropy Δnr for red wavelength light are
Δnb / Δng = 1.04 ± 0.03,
Δnr / Δng = 0.96 ± 0.03,
It is said. Accordingly, for example, the red pixel liquid crystal layer thickness dr, the green pixel liquid crystal layer thickness dg, and the blue pixel liquid crystal layer thickness db are determined. In this liquid crystal display element, the retardation Δn · d is appropriately set in the range of 450 nm to 550 nm for each color.

  In the present liquid crystal display element, the thickness of the color filter of each color is set so that the sum of the thickness of the liquid crystal layer 110 corresponding to the pixel of each color determined as described above and the thickness of the color filter of each color becomes a constant value. Is set.

  Here, the optical configuration of the liquid crystal cell 1 will be further described with reference to an exploded plan view showing the optical configuration of the liquid crystal display element shown in FIG. First, the axis in the description of this embodiment is defined as follows. A horizontal axis 1h is defined as an axis parallel to the left and right sides when the liquid crystal display element is viewed from the observation side (front side polarizing plate 2 side) of the liquid crystal cell 1 having a rectangular shape. Further, in FIG. 2, the angle is 0 ° on the right side of the horizontal axis 1h, and the counterclockwise direction is the + direction. At this time, as shown in the third row of FIG. 2, the front horizontal alignment film alignment direction 16 a that is the direction of the grooves carved in the front horizontal alignment film 16 is a + 45 ° direction. On the other hand, the rear horizontal alignment film alignment direction 19a which is the direction of the grooves carved in the rear horizontal alignment film 19 is a direction of −45 °. However, in actuality, since manufacturing errors and the like are included, the width of ± 5 ° is considered. Accordingly, FIG. 2 shows “+ 45 ° ± 5 °” and “−45 ° ± 5 °”. Similarly, it is considered that the angle has a certain width. Due to the grooves carved in the front horizontal alignment film 16 and the rear horizontal alignment film 19, the liquid crystal molecules of the liquid crystal layer 110 are in front of the surface of the rear horizontal alignment film 19 when no electric field is formed there. As shown by the arrow 21, they are arranged in a twisted state at an angle of −90 ° ± 5 ° toward the surface of the horizontal alignment film 16.

  Thus, for example, the liquid crystal cell 1 including the front glass substrate 11, the rear glass substrate 12, the common electrode 15, the front horizontal alignment film 16, the pixel electrode 17, the rear horizontal alignment film 19, the liquid crystal layer 110, and the liquid crystal molecules 110a includes: A front substrate and a rear substrate, which have been subjected to alignment treatment in a direction of 90 °, on the surfaces facing each other on which electrodes are formed, and a 90 ° twist of liquid crystal molecules between the front substrate and the rear substrate. It functions as a liquid crystal element having a liquid crystal layer provided with twist alignment at corners.

  A front polarizing plate 2 is disposed on the outermost side of the liquid crystal display element on the front glass substrate 11 side of the liquid crystal cell 1. The installation angle is an angle at which the front polarizing plate transmission axis 2a which is the transmission axis of the front polarizing plate 2 is perpendicular to the horizontal axis 1h as shown in the first row of FIG. Therefore, the front polarizing plate transmission axis 2a and the front horizontal alignment film alignment direction 16a of the liquid crystal cell 1 form an angle of 45 ° ± 5 °.

  A rear polarizing plate 3 is disposed on the outermost side of the liquid crystal display element on the rear glass substrate 12 side of the liquid crystal cell 1. The installation angle is an angle at which the rear polarizing plate transmission axis 3a, which is the transmission axis of the rear polarizing plate 3, is parallel to the horizontal axis 1h as shown in the sixth row of FIG. Therefore, the rear polarizing plate transmission axis 3a and the rear horizontal alignment film alignment direction 19a of the liquid crystal cell 1 form an angle of 45 ° ± 5 °. The angle formed by the rear polarizing plate transmission axis 3a and the front polarizing plate transmission axis 2a is 90 ° ± 5 °. This can be paraphrased as follows. A direction of + 270 °, which is an intermediate angle direction in the twist angle range, in a state of being twisted from the surface of the rear horizontal alignment film 19 toward the surface of the front horizontal alignment film 16 is indicated by a white arrow 20. The front polarizing plate 2 is arranged so that the front polarizing plate transmission axis 2a is parallel to the + 270 ° direction. In addition, the rear polarizing plate 3 is arranged so that the rear polarizing plate transmission axis 3a is orthogonal to the + 270 ° direction indicated by the white arrow 20.

  Thus, for example, the front polarizing plate 2 functions as a front polarizing plate arranged so that the transmission axis forms an angle of 45 ° with respect to the direction of the alignment treatment of the front substrate. It functions as a rear polarizing plate arranged so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate.

  A front viewing angle compensation film 4 is disposed between the front glass substrate 11 of the liquid crystal cell 1 and the front polarizing plate 2. As shown in FIG. 1, the front viewing angle compensation film 4 is formed on a front viewing angle compensation film substrate 41 which is a transparent film substrate in contact with the front polarizing plate 2 and on the surface opposite to the front polarizing plate 2 side. A front viewing angle compensation film alignment film 42 and a front viewing angle compensation film discotic liquid crystal layer 43 laminated on the surface of the front viewing angle compensation film alignment film 42. The front viewing angle compensation film discotic liquid crystal layer 43 includes disc-shaped discotic liquid crystal molecules 43a. The normal direction of the discotic liquid crystal molecules 43a with respect to the disc surface is defined as a molecular axis 43b. The molecular axes 43b of the discotic liquid crystal molecules 43a are aligned in a plane perpendicular to the front viewing angle compensation film 4 in accordance with the alignment treatment direction applied to the front viewing angle compensation film alignment film. FIG. 3 shows a schematic cross-sectional view of the front viewing angle compensation film 4 having a cross section of this vertical plane. The discotic liquid crystal molecules 43a adjacent to the front viewing angle compensation film alignment film 42 are aligned with their molecular axes 43b substantially perpendicular to the front viewing angle compensation film alignment film 42. That is, the tilt angle of the disc surface with respect to the front viewing angle compensation film alignment film 42, that is, the tilt angle is substantially 0 °. The tilt angle of the discotic liquid crystal molecules 43a gradually increases as the distance from the front viewing angle compensation film alignment film 42 increases.

  Similarly, a rear viewing angle compensation film 5 is disposed between the rear glass substrate 12 of the liquid crystal cell 1 and the rear polarizing plate 3. The rear viewing angle compensation film 5 includes a rear viewing angle compensation film substrate 51 that is a transparent film substrate in contact with the rear polarizing plate 3 and a rear side that is formed on the surface opposite to the rear polarizing plate 3 side. A viewing angle compensation film alignment film 52 and a rear viewing angle compensation film discotic liquid crystal layer 53 laminated on the surface of the rear viewing angle compensation film alignment film 52 are provided. The molecular axis 53b of the discotic liquid crystal molecules 53a in the rear viewing angle compensation film discotic liquid crystal layer 53 is aligned with the rear viewing angle compensation film 5 in accordance with the alignment treatment direction applied to the rear viewing angle compensation film alignment film 52. It is aligned in a vertical plane. The tilt angle of the discotic liquid crystal molecules 53a adjacent to the rear viewing angle compensation film alignment film 52 is approximately 0 °. The tilt angle of the discotic liquid crystal molecules 53a gradually increases as the distance from the rear viewing angle compensation film alignment film 52 increases.

  The discotic liquid crystal molecules 43a and the discotic liquid crystal molecules 53a have negative optical anisotropy along the lodging direction. For example, the front viewing angle compensation film discotic liquid crystal layer 43 has a negative optical axis having an optical axis with a minimum refractive index in a direction (direction N indicated by an arrow in FIG. 3) in which the inclination angles of the molecular axes 43b are averaged. Expresses optical anisotropy. The same applies to the rear viewing angle compensation film discotic liquid crystal layer 53.

  Here, the film surface projection direction in the direction N which is the average of the directions of the molecular axes 43b shown in FIG. 3 is defined as the front viewing angle compensation film optical axis 4a. In the liquid crystal display element, the front viewing angle compensation film 4 has the same front viewing angle compensation film optical axis 4a as the front horizontal alignment film alignment direction 16a of the liquid crystal cell 1 (+45) as shown in the second stage of FIG. (° ± 5 ° direction). The film surface projection direction in the direction N, which is the average of the directions of the molecular axes 53b of the rear viewing angle compensation film 5, is defined as the rear viewing angle compensation film optical axis 5a. In the rear viewing angle compensation film 5, as shown in the fourth row of FIG. 2, the rear viewing angle compensation film optical axis 5a is the same as the rear horizontal alignment film alignment direction 19a of the liquid crystal cell 1 (−45 ° ± (5 ° direction).

  Thus, for example, the front viewing angle compensation film 4 has negative optical anisotropy that minimizes the refractive index in the direction inclined in a specific direction with respect to the normal of the film surface of the front optical anisotropic film, It functions as a front optical anisotropic film in which the angle formed between the direction in which the specific direction having the minimum refractive index is projected onto the film surface and the orientation processing direction of the front substrate is 0 °, for example, rear viewing angle compensation The film 5 has negative optical anisotropy in which the refractive index in the direction inclined in a specific direction with respect to the normal line of the film surface of the rear optical anisotropic film is minimum, and the specific index in which the refractive index is minimum It functions as a rear optical anisotropic film in which an angle formed by a direction projected onto the film surface and an orientation processing direction of the rear substrate is 0 °.

  Next, in the liquid crystal display element according to the present embodiment, which is composed of the liquid crystal cell 1, the front polarizing plate 2, the rear polarizing plate 3, the front viewing angle compensation film 4, and the rear viewing angle compensation film 5 as described above. The effects of the liquid crystal display element that does not include the black compensation phase difference plate 9 will be described with reference to the drawings. 4 shows an initial alignment state of liquid crystal molecules when no electric field is formed in the liquid crystal layer 110, and FIG. 5 shows a rising alignment state of liquid crystal molecules when an electric field is formed in the liquid crystal layer 110. 4 and 5, (a) is a plan view when the liquid crystal layer is viewed from the observation side, and (b) is a cross-sectional view showing an arrangement state of liquid crystal molecules between the substrates.

  In the initial alignment state shown in FIG. 4, the liquid crystal molecules 110a in the vicinity of the front horizontal alignment film 16 and the rear horizontal alignment film 19 receive the alignment regulating force of the front horizontal alignment film 16 or the rear horizontal alignment film 19, The major axis direction is set along the direction of the front horizontal alignment film alignment direction 16a or the rear horizontal alignment film alignment direction 19a, respectively. The liquid crystal molecules 110a are aligned in a state where the downstream end of the front horizontal alignment film alignment direction 16a or the rear horizontal alignment film alignment direction 19a is lifted by the pretilt angle θ. The liquid crystal molecules 110 a in the liquid crystal layer 110 are aligned between the front horizontal alignment film 16 and the rear horizontal alignment film 19 between the liquid crystal molecules 110 a and the rear horizontal alignment film 19 that are aligned in the vicinity of the front horizontal alignment film 16. The liquid crystal molecules 110a aligned in the vicinity are continuously twisted. That is, the liquid crystal molecules 110a are twisted and aligned in the direction of the arrow 21 clockwise by approximately 90 ° from the rear horizontal alignment film 19 side to the front horizontal alignment film 16 side. The liquid crystal layer 110 in which the liquid crystal molecules 110a are twist-aligned over 90 degrees is set to have birefringence that causes a phase difference of ½ of the wavelength λ of the transmitted light. Accordingly, the linearly polarized light that enters and passes through the liquid crystal layer 110 is emitted as linearly polarized light whose polarization plane is rotated by 90 °.

  When the operational effects of the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 are not taken into consideration, irradiation light from a backlight (not shown) installed on the rear side of the rear polarizing plate 3 The light is transmitted, and the polarization plane becomes linearly polarized light along the rear polarizing plate transmission axis 3 a and enters the liquid crystal layer 110. When entering the liquid crystal layer 110 in the initial alignment state, a phase difference of λ / 2 is imparted when passing through the liquid crystal layer 110, and the polarization plane is rotated by 90 °. As shown in FIG. 2, since the rear polarizing plate transmission axis 3a and the front polarizing plate transmission axis 2a are orthogonal to each other, the polarization plane of the liquid crystal layer 110 is rotated by 90 ° through the rear polarizing plate 3. The light passes through the front polarizing plate 2 without being absorbed and is emitted from the front polarizing plate 2. As a result, a bright display is made.

  On the other hand, when an electric field is formed in the liquid crystal layer 110, the major axis of the liquid crystal molecules 110a in the liquid crystal layer 110 is oriented in the direction of the electric field, that is, in the direction perpendicular to the front glass substrate 11 and the rear glass substrate 12. In addition, force acts on the liquid crystal molecules 110a. As a result, the state shown in FIG. 5 is obtained. At this time, the liquid crystal molecules 110a in the vicinity of the front horizontal alignment film 16 and the rear horizontal alignment film 19 are strongly subjected to the alignment regulating force by the front horizontal alignment film 16 or the rear horizontal alignment film 19, so-called anchoring effect. I can't get up enough. Therefore, the pretilt angle θ of the liquid crystal molecules 110a in the vicinity of the front horizontal alignment film 16 and the rear horizontal alignment film 19 is substantially the same as the initial state, and the major axis direction is the front horizontal alignment film alignment direction 16a and the rear horizontal alignment. The direction formed by dividing the angle formed by the film alignment direction 19a into two equal parts, that is, the direction rotated by + 45 ° from the front horizontal alignment film alignment direction 16a, and the direction rotated by −45 ° from the rear horizontal alignment film alignment direction 19a Oriented towards. The liquid crystal molecules 110 a in the liquid crystal layer 110 are continuously aligned with the liquid crystal molecules 110 a aligned in the vicinity of the front horizontal alignment film 16 and the liquid crystal molecules 110 a aligned in the vicinity of the rear horizontal alignment film 19. . Accordingly, as the distance from the front horizontal alignment film 16 and the rear horizontal alignment film 19 increases, the rising angle of the liquid crystal molecules 110 a increases, and the liquid crystal molecules 110 a located in the middle of the thickness direction of the liquid crystal layer 110 are aligned substantially vertically. To do. As described above, when a sufficiently large electric field is formed in the liquid crystal layer, the liquid crystal molecules 110a in the liquid crystal layer 110 are unscrewed, and as shown in FIG. Are aligned substantially in the direction indicated by the white arrow 20. The liquid crystal layer 110 in this state does not give a phase difference to the transmitted light.

  In the case where the operational effects of the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 are not taken into account, in the present liquid crystal display element, irradiation light from a backlight (not shown) is transmitted through the rear polarizing plate 3 and has a polarization plane. It becomes linearly polarized light along the rear polarizing plate transmission axis 3a and enters the liquid crystal layer 110 in a state where the liquid crystal molecules 110a rise. This light passes through the liquid crystal layer 110 as linearly polarized light without being given a phase difference. The direction of the polarization plane of the linearly polarized light transmitted through the liquid crystal layer 110 is the direction along the front polarizing plate absorption axis 2 b, so that the linearly polarized light transmitted through the liquid crystal layer 110 is absorbed by the front polarizing plate 2. As a result, dark display is performed.

  As described above, because of the grooves carved in the front horizontal alignment film 16 and the rear horizontal alignment film 19, the liquid crystal molecules 110 a move from the surface of the rear horizontal alignment film 19 to the surface of the front horizontal alignment film 16. As shown by 21, they are arranged in a twisted state at −90 ° ± 5 °. Therefore, there is a viewing angle direction in which the best contrast is obtained in the liquid crystal display element in the direction of + 270 ° in FIG. 2 indicated by the white arrow 20, which is the middle angle direction of the twist angle range. For example, when observing a liquid crystal display element as a display unit such as a mobile phone, the observation direction is the normal direction to the display surface, that is, directly in front, or slightly below the horizontal direction of the display element, that is, +270 in the coordinate axis. It is often seen from the direction of °. Therefore, it is preferable that the viewing angle direction in which the best contrast is obtained in the liquid crystal display element is in the + 270 ° direction. In consideration of this, in the present embodiment, the front horizontal alignment film alignment direction 16a and the rear horizontal alignment film alignment direction 19a are set to the + 45 ° direction and the −45 ° direction, respectively.

  In general, gradation inversion of the intermediate gradation of the liquid crystal display element occurs in an orientation that coincides with the major axis direction of the liquid crystal molecules 110a. Therefore, in this embodiment, when an electric field is formed in the liquid crystal layer 110, the front polarizing plate transmission axis 2a is aligned with the 270 ° azimuth in which the major axes of the liquid crystal molecules 110a are aligned, and the display of the liquid crystal display element is displayed in 270. Gradation inversion at intermediate gradations when observed from the azimuth direction was suppressed.

  Thus, in order to determine the design of the liquid crystal display element having good display quality, first, in the present example, the directions of the front polarizing plate transmission axis 2a and the rear polarizing plate transmission axis 3a were determined.

  Further, in the present liquid crystal display element, it is calculated by an equation (√3 · λ / 2) indicating a retardation value necessary for rotating the polarization plane of transmitted light by 90 °, and red, green, The value of retardation Δn · d was appropriately set in the range of 450 nm to 550 nm for each blue color. Based on the result, a multi-gap structure having a different liquid crystal layer thickness for each color was obtained. For this reason, it is a liquid crystal display element in which good dark display with sufficiently low transmittance and light display with good chromaticity can be obtained for light of all colors.

  Next, functions and effects of the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 will be described. In the liquid crystal display element that does not have the front viewing angle compensation film 4 and the rear viewing angle compensation film 5, with respect to the light that has passed through the rear polarizing plate 3 and entered the liquid crystal layer 110, The retardation for light incident from an oblique direction is different. For this reason, the transmittance varies depending on the incident direction of light, the viewing angle that is an observation angle range in which the display can be observed with a good contrast is narrow, and a band color is generated in the display.

  On the other hand, in the present liquid crystal display element, the front viewing angle compensation film 4 and the rear viewing angle are provided between the liquid crystal cell 1 and the front polarizing plate 2 and between the liquid crystal cell 1 and the rear polarizing plate 3, respectively. A compensation film 5 is inserted. Here, the front viewing angle compensation film optical axis 4a and the rear viewing angle compensation film, which are the film surface projection directions in the direction N of the axis where the refractive index of the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 is minimum, are used. The optical axes 5a are arranged so as to be along the front horizontal alignment film alignment direction 16a and the rear horizontal alignment film alignment direction 19a, respectively. Therefore, the difference between the retardation with respect to the light incident on the liquid crystal layer 110 from the vertical direction and the retardation with respect to the light incident from the oblique direction is compensated by the front viewing angle compensation film 4 and the rear viewing angle compensation film 5. Therefore, the difference in transmittance of incident light from various directions can be reduced, and a wide viewing angle can be obtained. Moreover, the display band color could be suppressed.

  Further, the tilt angles of the discotic liquid crystal molecules 43a and the discotic liquid crystal molecules 53a gradually increase as the distance from the front viewing angle compensation film alignment film 42 and the rear viewing angle compensation film alignment film 52 increases. For this reason, when an electric field is applied to the liquid crystal layer 110, the remaining retardation due to the anchoring effect on the liquid crystal molecules 110 a is also compensated by the front viewing angle compensation film 4 and the rear viewing angle compensation film 5.

  The directions of the front viewing angle compensation film optical axis 4a and the rear viewing angle compensation film optical axis 5a may be directions rotated by 180 ° with respect to the above directions. That is, the same effect can be obtained even when the direction of the front viewing angle compensation film optical axis 4a is 225 ° and the direction of the rear viewing angle compensation film optical axis 5a is 135 °.

  Thus, in order to determine the design of the liquid crystal display element having good display quality, in this embodiment, the front viewing angle is next to the front polarizing plate transmission axis 2a and the rear polarizing plate transmission axis 3a. The directions of the compensation film optical axis 4a and the rear viewing angle compensation film optical axis 5a were determined.

  A liquid crystal display element comprising the liquid crystal cell 1, the front polarizing plate 2, the rear polarizing plate 3, the front viewing angle compensation film 4, and the rear viewing angle compensation film 5 is the liquid crystal display device disclosed in Patent Document 1. . The viewing angle characteristics of the conventional liquid crystal display element are shown in FIG. This figure shows the value of light leakage during black display. The circumferential direction angle indicates the direction in which the liquid crystal display element is observed, and the direction corresponds to the angle defined in FIG. The axis indicated by the distance from the center represents the angle formed by the viewing direction and the normal line of the display surface of the liquid crystal display element. For example, the center 0 ° indicates a case where the liquid crystal display element is observed in a direction perpendicular to the display surface of the liquid crystal display element, that is, from the front, and the surroundings of 20 ° and 40 ° are, for example, 20 ° and 40 °. The case of observing from an oblique direction at an angle of 20 ° or 40 ° with respect to the normal line of the display surface is shown. The value of light leakage is 0 for a completely black state where no light is transmitted, and 1 for a state where all light is transmitted (air layer state). That is, in this case, the closer to 0, there is no light leakage during black display, and it can be said that the liquid crystal display element is desirable. As shown in FIG. 6, the present liquid crystal display element was observed from directions around 45 °, 135 °, 225 °, and 315 °, which are oblique directions with respect to the horizontal direction of the liquid crystal display element (1h in FIG. 2). It can be seen that light leakage is observed. This is a direction shifted by ± 45 ° from the front polarizing plate transmission axis 2a and the rear polarizing plate transmission axis 3a.

  The liquid crystal display element according to this example has a retardation plate in order to improve the light leakage in the oblique direction. That is, in this example, as shown in FIGS. 1 and 2 between the rear polarizing plate 3 and the rear viewing angle compensation film 5 of the conventional liquid crystal display element disclosed in Patent Document 1, as shown in FIGS. A black compensation phase difference plate 9 was inserted.

  Here, the thickness direction of the black compensation phase difference plate 9 is the z-axis direction, the slow axis having the highest refractive index along the plate surface is the s-axis direction, and is along the plate surface and orthogonal to the s-axis direction. The direction to perform is the f-axis direction. Further, the refractive indexes in the s-axis direction, the f-axis direction, and the z-axis direction are nx, ny, and nz, respectively. The thickness of the black compensation phase difference plate 9 is d. At this time, Nz = (ns−nz) / (ns−nf) and R0 = (ns−nf) d are defined.

  In this example, a uniaxial film with Nz = (ns−nz) / (ns−nf) = 1.0, that is, ns> nf = nz, was used for the black compensation phase difference plate 9. In order to determine the optimum conditions for introducing the black compensation phase difference plate 9, the black compensation phase difference plate slow axis 9a that is the s-axis direction of the black compensation phase difference plate 9 is set to 0 ° or 90 °. , R0 = (ns−nf) d was changed to various values, and light leakage during black display was examined.

  The relationship between the obtained R0 and the maximum value Tmax of light leakage is shown in FIGS. FIG. 7 shows a case where the black compensation phase difference plate slow axis 9a is 90 °, and FIG. 8 shows a case where the black compensation phase difference plate slow axis 9a is 0 °. When the black compensation retardation plate slow axis 9a was 90 °, as shown in FIG. 7, no significant suppression of light leakage during black display was observed. On the other hand, when the black compensation retardation plate slow axis 9a was 0 °, suppression of light leakage during black display was recognized as shown in FIG. In particular, Tmax was 0.02 (2%) or less in the range where R0 was 100 nm or more and 200 nm or less. When R0 is approximately 160 nm, the maximum value Tmax of light leakage takes the minimum value. The viewing angle characteristic when R0 = 160 nm is shown in FIG. When the black compensation phase difference plate 9 is introduced as compared with the maximum value Tmax of light leakage at the time of black display which was 0.066 (6.6%) when the black compensation phase difference plate 9 is not introduced. It decreased to about 1/7, 0.0095 (0.95%).

  Thus, for example, the black compensation phase difference plate 9 has a relationship of ns> nf = nz, and functions as a phase difference plate in which the angle formed between the s axis and the transmission axis of the rear polarizing plate is 0 °. To do.

  Thus, in order to determine the design of the liquid crystal display element having good display quality, in the present embodiment, the direction of the front viewing angle compensation film optical axis 4a and the rear viewing angle compensation film optical axis 5a is next. The direction of the black compensation phase difference plate slow axis 9a and the value of R0 = (ns−nf) d of the black compensation phase difference plate 9 were determined.

  As described above, in order to improve the viewing angle at the time of black display, Nz is uniaxial between the rear polarizing plate 3 and the rear viewing angle compensation film 5, and R0 = (ns−nf). ) The black compensation phase difference plate 9 having d of approximately 160 nm is set so that the direction of the black compensation phase difference plate slow axis 9a is 0 ° ± 5 °, that is, parallel to the rear polarizing plate transmission axis 3a. It arranged so that it might become. As a result, the viewing angle during black display of the liquid crystal display element was improved.

[First Modification of First Embodiment]
Next, a first modification of the first embodiment will be described. In the description of this modification, differences from the first embodiment will be described. In the liquid crystal display device according to the first embodiment, the front polarizing plate 2 is oriented in the direction in which the front polarizing plate transmission axis 2a is 0 °, and the rear polarizing plate 3 is in the direction in which the rear polarizing plate transmission axis 3a is 90 °. You may arrange so that it may become. In this case, if the black compensation phase difference plate 9 is arranged so that the black compensation phase difference plate slow axis 9a is in the direction of 90 °, the visual field at the time of black display is the same as in the first embodiment. The corner was improved.

[Second Modification of First Embodiment]
Next, a second modification of the first embodiment will be described. In the description of this modification, differences from the first embodiment will be described. Instead of the black compensation phase difference plate 9, the first black compensation phase difference plate is provided between the front polarizing plate 2 and the front viewing angle compensation film 4, and the rear polarizing plate 3 and the rear viewing angle compensation film 5. A second black compensation phase difference plate may be disposed between the two. This is equivalent to dividing the black compensation phase difference plate 9 into two sheets, a first black compensation phase difference plate and a second black compensation phase difference plate. In this case, the sum of R0 of the first black compensation phase difference plate and the second black compensation phase difference plate is approximately 160 nm, and their slow axes are both 0 ° (the front polarization plate 2 is transmitted through the front polarization plate 2). When the rear polarizing plate 3 is disposed so that the rear polarizing plate transmission axis 3a is in the direction of 90 ° in the direction in which the axis 2a is 0 °, the rear polarizing plate 3a is disposed in the direction of 90 °) As in the case of the first embodiment, the viewing angle during black display was improved. That is, when the thicknesses of the first black compensation phase difference plate and the second black compensation phase difference plate are d1 and d2, respectively, (ns−nf) (d1 + d2) is designed to be 160 nm. In this case, the same effect as in the first embodiment was obtained. Of course, R0 of the first black compensation phase difference plate and the second black compensation phase difference plate may be set to approximately 80 nm, respectively, and their slow axes may be arranged in the direction of 0 °.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Here, in the description of the second embodiment, differences from the first embodiment will be described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  As shown schematically in FIG. 10, the liquid crystal display element according to the second embodiment of the present invention includes a liquid crystal cell 1, a front polarizing plate 2, a rear polarizing plate 3, and a front viewing angle compensation film 4. The rear viewing angle compensation film 5, the front white compensation phase difference plate 6, the rear white compensation phase difference plate 7, and the black compensation phase difference plate 9 are configured. Here, the configurations of the liquid crystal cell 1, the front polarizing plate 2, the rear polarizing plate 3, the front viewing angle compensation film 4, and the rear viewing angle compensation film 5 are the same as those in the first embodiment.

  A front white compensation phase difference plate 6 is disposed between the front polarizing plate 2 and the front viewing angle compensation film 4, and between the rear polarizing plate 3 and the rear viewing angle compensation film 5. A rear white compensation phase difference plate 7 is provided. The front white compensation phase difference plate 6 is a uniaxial film, and is arranged so that its slow axis is parallel to the optical axis of the front viewing angle compensation film 4. The rear white compensation phase difference plate 7 is also a uniaxial film, and is arranged so that its slow axis is parallel to the optical axis of the rear viewing angle compensation film 5. For this reason, the retardation compensation effect by the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 is obtained by laminating the front white compensation phase difference plate 6 and the rear white compensation film, which are laminated with their optical axes aligned with each other. Further improvement is achieved by the phase difference plate 7. In particular, residual retardation in white display, that is, in a state where an electric field is not formed in the liquid crystal layer 110 is compensated, and viewing angle characteristics are improved.

  Further, the liquid crystal display element of this embodiment includes a black compensation phase difference plate 9 between the rear white compensation phase difference plate 7 and the rear side polarization plate 3. The black compensation phase difference plate 9 is a uniaxial film, and its slow axis is parallel to the transmission axis of the rear polarizing plate 3. By introducing such a black compensation phase difference plate 9, it is possible to further reduce light leakage during black display in a direction in which the transmission axes of the front polarizing plate 2 and the rear polarizing plate 3 are rotated by 45 °. it can. That is, by introducing the black compensation phase difference plate 9, the viewing angle at the time of black display is further improved as compared with the case without this.

  In designing the liquid crystal display device according to the present embodiment, first, while confirming the quality of the viewing angle characteristics, the alignment direction of the front horizontal alignment film 16 and the rear horizontal alignment film 19 of the liquid crystal cell 1 and the front polarization The positional relationship between the transmission axes of the plate 2 and the rear polarizing plate 3 is determined. Next, in order to improve the viewing angle characteristics of the liquid crystal display element composed of the liquid crystal cell 1, the front polarizing plate 2, and the rear polarizing plate 3, the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 Consider insertion. Again, the positional relationship between these optical axes is determined while checking the viewing angle characteristics. In order to further improve the viewing angle characteristics, the insertion of the front white compensation phase difference plate 6 and the rear white compensation phase difference plate 7 will be examined. Again, the positional relationship between these optical axes is determined while checking the viewing angle characteristics. Furthermore, in order to improve the viewing angle characteristics, the insertion of the black compensation phase difference plate 9 is examined, and the positional relationship between these optical axes is determined while checking the viewing angle characteristics.

[Second Embodiment]
Next, an example of the liquid crystal display element according to the second embodiment will be described in detail with reference to the drawings. As shown in FIG. 10, the liquid crystal display element includes, in order from the observation side of the liquid crystal display element, a front polarizing plate 2, a front white compensation phase difference plate 6, a front viewing angle compensation film 4, a liquid crystal cell 1, and a rear side. It has a viewing angle compensation film 5, a rear white compensation phase difference plate 7, a black compensation phase difference plate 9, and a rear side polarization plate 3.

  The configuration of the liquid crystal cell 1 is the same as that in the first embodiment. However, in this liquid crystal display element, the retardation Δn · d is appropriately set in the range of 350 nm to 450 nm for each color.

  The optical configuration of the liquid crystal display element will be described with reference to FIG. The definitions of axes and angles in FIG. 11 are the same as those in FIG. The optical configuration of the liquid crystal cell 1 is shown in the fourth row of FIG. The front horizontal alignment film alignment direction 16a, which is the direction of grooves engraved in the front horizontal alignment film 16, is a direction of + 45 ° with respect to the horizontal axis 1h, and is the direction of grooves engraved in the rear horizontal alignment film 19. A rear horizontal alignment film alignment direction 19a is a direction of −45 ° with respect to the horizontal axis 1h. However, since this angle actually includes a manufacturing error or the like, in this embodiment, it is assumed that a width of ± 5 ° is provided as in the case of the first embodiment. Accordingly, FIG. 2 shows “+ 45 ° ± 5 °” and “−45 ° ± 5 °”.

  A front polarizing plate 2 is disposed on the outermost side of the liquid crystal display element on the front glass substrate 11 side of the liquid crystal cell 1. The installation angle is an angle at which the front polarizing plate transmission axis 2a that is the transmission axis of the front polarizing plate 2 is perpendicular to the horizontal axis 1h, as shown in the first row of FIG. Therefore, the front polarizing plate transmission axis 2a and the front horizontal alignment film alignment direction 16a form an angle of 45 ° ± 5 °.

  A rear polarizing plate 3 is disposed on the outermost side of the liquid crystal display element on the rear glass substrate 12 side of the liquid crystal cell 1. The installation angle is an angle at which the rear polarizing plate transmission axis 3a which is the transmission axis of the rear polarizing plate 3 is parallel to the horizontal axis 1h as shown in the eighth row of FIG. Therefore, the rear polarizing plate transmission axis 3a and the rear horizontal alignment film alignment direction 19a form an angle of 45 ° ± 5 °. The angle formed by the rear polarizing plate transmission axis 3a and the front polarizing plate transmission axis 2a is 90 ° ± 5 °.

  As described above, because of the grooves carved in the front horizontal alignment film 16 and the rear horizontal alignment film 19, the liquid crystal molecules 110 a move from the surface of the rear horizontal alignment film 19 to the surface of the front horizontal alignment film 16. As shown by 21, they are arranged in a twisted state at −90 ° ± 5 °. Therefore, there is a viewing angle direction in which the best contrast can be obtained in the liquid crystal display element in the direction of + 270 ° indicated by the white arrow 20 which is an intermediate angle direction of the twist angle range. In consideration of this, in the present embodiment, the front horizontal alignment film alignment direction 16a and the rear horizontal alignment film alignment direction 19a are set to the + 45 ° direction and the −45 ° direction, respectively.

  In general, gradation inversion of the intermediate gradation of the liquid crystal display element occurs in an orientation that coincides with the major axis direction of the liquid crystal molecules 110a. Therefore, in this embodiment, when an electric field is formed in the liquid crystal layer 110, the front polarizing plate transmission axis 2a is aligned with the + 270 ° azimuth in which the major axes of the liquid crystal molecules 110a are aligned, and the display of the liquid crystal display element is +270. Gradation inversion at intermediate gradations when observed from the azimuth direction was suppressed.

  Thus, in order to determine the design of the liquid crystal display element having good display quality, the directions of the front polarizing plate transmission axis 2a and the rear polarizing plate transmission axis 3a were also determined in this example.

  The configurations of the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 are the same as those in the first embodiment. The front viewing angle compensation film optical axis 4a is positioned in the same direction (+ 45 ° ± 5 ° direction) as the front horizontal alignment film alignment direction 16a of the front horizontal alignment film of the liquid crystal cell 1, as shown in the third row of FIG. Are arranged. The rear viewing angle compensation film optical axis 5a is the same as the rear horizontal alignment film alignment direction 19a of the rear horizontal alignment film of the liquid crystal cell 1 as shown in the fifth row of FIG. °)). The directions of the front viewing angle compensation film optical axis 4a and the rear viewing angle compensation film optical axis 5a may be directions rotated by 180 ° with respect to the above directions. That is, the same effect can be obtained even when the direction of the front viewing angle compensation film optical axis 4a is 225 ° and the direction of the rear viewing angle compensation film optical axis 5a is 135 °.

  Thus, in order to determine the design of the liquid crystal display element having good display quality, in this embodiment, the front viewing angle is next to the front polarizing plate transmission axis 2a and the rear polarizing plate transmission axis 3a. The directions of the compensation film optical axis 4a and the rear viewing angle compensation film optical axis 5a were determined.

  In the present embodiment, a front white compensation phase difference plate 6 is further disposed between the front polarizing plate 2 and the front viewing angle compensation film 4, and the rear polarizing plate 3 and the rear viewing angle compensation film 5 are disposed. The white compensation phase difference plate 7 is disposed between the two.

  Here, the thickness direction of the retardation film is defined as the z-axis direction, the slow axis having the highest refractive index along the plate surface is defined as the s-axis direction, and the direction along the plate surface and orthogonal to the s-axis direction is defined as f. Axial direction. Further, the refractive indexes in the s-axis direction, the f-axis direction, and the z-axis direction are nx, ny, and nz, respectively. The thickness of the black compensation phase difference plate 9 is d. At this time, Nz = (ns−nz) / (ns−nf) and R0 = (ns−nf) d are defined.

  The front white compensation phase difference plate 6 is a uniaxial film, and is a film that satisfies a relationship of Nz = (ns−nz) / (ns−nf) = 1.0, that is, ns> nf = nz. The front white compensation retardation plate slow axis 6a, which is the slow axis, is parallel to the front viewing angle compensation film optical axis 4a of the front viewing angle compensation film 4, that is, in the + 45 ° ± 5 ° direction. Are arranged as follows. Incidentally, R0 = (ns−nf) d of the front white compensation phase difference plate 6 is 45 nm. The rear white compensation phase difference plate 7 is also a uniaxial film like the front white compensation phase difference plate 6, and Nz = (ns−nz) / (ns−nf) = 1.0. In the rear white compensation phase difference plate 7, the rear white compensation phase difference plate slow axis 7 a, which is the slow axis, is parallel to the rear viewing angle compensation film optical axis 5 a of the rear viewing angle compensation film 5. That is, it is arranged to be in the direction of −45 ° ± 5 °. Incidentally, R0 = (ns−nf) d of the rear white compensation phase difference plate 7 is also 45 nm.

  According to the present embodiment, the retardation compensation effects of the front viewing angle compensation film 4 and the rear viewing angle compensation film 5 are respectively obtained by laminating the front white compensation phase difference plate 6 and the front white compensation phase difference plate 6 laminated with the optical axes aligned with each other. Further improvement is achieved by the rear white compensation phase difference plate 7. In particular, residual retardation in white display, that is, in a state where an electric field is not formed in the liquid crystal layer 110 is compensated, and viewing angle characteristics are improved.

  Thus, for example, the front white compensation phase difference plate 6 has a relationship of ns> nf = nz, and is arranged with the angle formed by the s axis and the optical axis of the front optical anisotropic film being 0 °. For example, the rear white compensation retardation plate 7 has a relationship of ns> nf = nz, and is formed by the s axis and the optical axis of the rear optical anisotropic film. It functions as a second retardation plate arranged with an angle of 0 °.

  Thus, in order to determine the design of the liquid crystal display element having good display quality, in the present embodiment, the direction of the front viewing angle compensation film optical axis 4a and the rear viewing angle compensation film optical axis 5a is next. The direction of the front white compensation phase difference plate slow axis 6a and the direction of the rear white compensation phase difference plate slow axis 7a, and R0 of the front white compensation phase difference plate 6 and the rear white compensation phase difference plate 7 = The value of (ns−nf) d was determined.

  Here, the liquid crystal cell 1, the front polarizing plate 2, the rear polarizing plate 3, the front viewing angle compensation film 4, the rear viewing angle compensation film 5, the front white compensation retardation plate 6, and the rear white compensation retardation plate. 7 is a liquid crystal display element disclosed in Patent Document 1. The viewing angle characteristics of the conventional liquid crystal display element are shown in FIG. This figure shows the value of light leakage during black display. The definition of the axes and the like is the same as that in FIG. As shown in FIG. 12, the present liquid crystal display element is observed from directions around 45 °, 135 °, 225 °, and 315 ° that are oblique to the horizontal direction (1h in FIG. 11) of the liquid crystal display device. It can be seen that light leakage is observed. This is a direction shifted by 45 ° from the front polarizing plate transmission axis 2a and the rear polarizing plate transmission axis 3a.

  In the liquid crystal display element in this embodiment, a retardation plate is introduced in order to improve the light leakage in the oblique direction. In the liquid crystal display element according to the present embodiment, as shown in FIGS. 10 and 11, the rear polarizing plate 3 and the rear white compensation phase difference plate 7 of the conventional liquid crystal display element disclosed in Patent Document 1 are disclosed. In between, the black compensation phase difference plate 9 was introduced.

  In this embodiment, the black compensation phase difference plate 9 is a uniaxial film in which Nz = (ns−nz) / (ns−nf) = 1.0. In order to determine the optimum conditions for introducing the black compensation phase difference plate 9, the black compensation phase difference plate slow axis 9a that is the s-axis direction of the black compensation phase difference plate 9 is set to 0 ° or 90 °. , R0 = (ns−nf) d was changed to various values, and light leakage during black display was examined.

  The relationship between the obtained R0 and the maximum value Tmax of light leakage is shown in FIGS. Here, FIG. 13 shows a case where the black compensation phase difference plate slow axis 9a is 90 °, and FIG. 14 shows a case where the black compensation phase difference plate slow axis 9a is 0 °. When the black compensation retardation plate slow axis 9a was 90 °, as shown in FIG. 13, no significant suppression of light leakage during black display was observed. On the other hand, when the black compensation retardation plate slow axis 9a was 0 °, suppression of light leakage during black display was recognized as shown in FIG. In particular, Tmax was 0.02 (2%) or less in the range where R0 was 80 nm or more and 180 nm or less. It has been clarified that when the phase difference R0 is approximately 140 nm, the maximum value Tmax of light leakage takes the minimum value. The viewing angle characteristics when R0 = 140 nm are shown in FIG. When the black compensation phase difference plate 9 is not introduced, the maximum value Tmax of light leakage during black display, which was 0.038 (3.8%), is 0.013 when the black compensation phase difference plate 9 is introduced. (1.3%) and reduced to about 1/3.

  Thus, for example, the black compensation phase difference plate 9 has a relationship of ns> nf = nz, and is arranged with the third angle arranged with the angle formed between the s-axis and the transmission axis of the rear polarizing plate being 0 °. Functions as a phase difference plate.

  In this way, in order to determine the design of the liquid crystal display element having good display quality, in this embodiment, the front white compensation phase difference plate slow axis 6a and the rear white compensation phase difference plate slow axis are determined. Next to the direction of 7a and the value of R0 = (ns−nf) d of the front white compensation phase difference plate 6 and the rear white compensation phase difference plate 7, the direction of the black compensation phase difference plate slow axis 9a Then, the value of R0 = (ns−nf) d of the black compensation phase difference plate 9 was determined.

  As described above, in order to improve the viewing angle at the time of black display, Nz is uniaxial between the rear polarizing plate 3 and the rear white compensation phase difference plate 7, and R0 = (ns -Nf) The black compensation phase difference plate 9 having d of approximately 140 nm is set so that the direction of the slow axis 9a of the black compensation phase difference plate is 0 ° ± 5 °, that is, the rear polarizing plate transmission axis 3a Introduced to be parallel to As a result, the viewing angle during black display was improved.

[First Modification of Second Embodiment]
Next, a first modification of the second embodiment will be described. In the description of this modification, differences from the second embodiment will be described. In the liquid crystal display device according to the second example, the front polarizing plate 2 is oriented in the direction in which the front polarizing plate transmission axis 2a is 0 °, and the rear polarizing plate 3 is in the direction in which the rear polarizing plate transmission axis 3a is 90 °. You may arrange so that it may become. In this case, if the black compensation phase difference plate 9 is arranged so that the black compensation phase difference plate slow axis 9a is in the direction of 90 °, as in the second embodiment, the visual field at the time of black display is displayed. The corner was improved.

[Second Modification of Second Embodiment]
Next, a second modification of the second embodiment will be described. In the description of this modification, differences from the second embodiment will be described. Instead of the black compensation phase difference plate 9, the first black compensation phase difference plate is provided between the front side polarization plate 2 and the front side white compensation phase difference plate 6, and the rear side polarization plate 3 and the rear side white compensation value. A second black compensation phase difference plate may be disposed between the phase difference plate 7 and the second phase difference plate 7. This is equivalent to dividing the black compensation phase difference plate 9 into two sheets, a first black compensation phase difference plate and a second black compensation phase difference plate. In this case, the sum of R0 of the first black compensation phase difference plate and the second black compensation phase difference plate is set to about 140 nm, and their slow axes are both 0 ° (the front polarizing plate 2 is transmitted through the front polarizing plate 2). When the rear polarizing plate 3 is disposed so that the rear polarizing plate transmission axis 3a is in the direction of 90 ° in the direction in which the axis 2a is 0 °, the rear polarizing plate 3a is disposed in the direction of 90 °) As in the case of the second embodiment, the viewing angle during black display was improved. That is, when the thicknesses of the first black compensation phase difference plate and the second black compensation phase difference plate are d1 and d2, respectively, (ns−nf) (d1 + d2) is designed to be 140 nm. In this case, the same effect as in the first embodiment was obtained. Of course, R0 of the first black compensation phase difference plate and the second black compensation phase difference plate may be set to approximately 70 nm, respectively, and their slow axes may be arranged in the direction of 0 °.

  In addition, this invention is not limited to the said embodiment, an Example, and a modification example as it is, In the implementation stage, a component can be deform | transformed and embodied in the range which does not deviate from the summary. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment, examples, and modifications. For example, even if some components are deleted from all the components shown in the embodiments, examples, and modifications, the problems described in the column of problems to be solved by the invention can be solved, and When an effect is obtained, a configuration from which this component is deleted can also be extracted as an invention. Furthermore, constituent elements over different embodiments, examples, and modifications may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal cell, 2 ... Front side polarizing plate, 2a ... Front side polarizing plate transmission axis, 2b ... Front side polarizing plate absorption axis, 3 ... Rear side polarizing plate, 3a ... Rear side polarizing plate transmission axis, 3b ... Rear side polarizing plate absorption Axis, 4 ... front viewing angle compensation film, 4a ... front viewing angle compensation film optical axis, 5 ... rear viewing angle compensation film, 5a ... rear viewing angle compensation film optical axis, 6 ... front white compensation phase difference plate, 6a: front white compensation phase difference plate slow axis, 7: rear white compensation phase difference plate, 7a: rear white compensation phase difference plate slow axis, 9: black compensation phase difference plate, 9a: black Compensation retardation plate slow axis, 11 ... front glass substrate, 12 ... rear glass substrate, 13 ... black mask, 14R ... red color filter, 14G ... green color filter, 14B ... blue color filter, 15 ... common electrode, 16 ... Front horizontal alignment film, 16a ... Front horizontal alignment film alignment direction, 17 ... Image Electrode, 18 ... Thin film transistor, 19 ... Rear horizontal alignment film, 19a ... Rear horizontal alignment film alignment direction, 110 ... Liquid crystal layer, 110a ... Liquid crystal molecule, 41 ... Front viewing angle compensation film substrate, 42 ... Front viewing angle compensation film Alignment film, 43 ... front viewing angle compensation film discotic liquid crystal layer, 43a ... discotic liquid crystal molecule, 43b ... molecular axis, 51 ... rear viewing angle compensation film substrate, 52 ... rear viewing angle compensation film alignment film, 53 ... Rear viewing angle compensation film discotic liquid crystal layer, 53a... Discotic liquid crystal molecules, 53b.

Claims (20)

A front substrate and a rear substrate, which have been subjected to alignment treatment in a direction of 90 °, on the surfaces facing each other on which electrodes are formed, and a 90 ° twist of liquid crystal molecules between the front substrate and the rear substrate. A liquid crystal element having a liquid crystal layer provided with twist orientation at corners;
A front polarizing plate disposed on the side opposite to the liquid crystal layer side with respect to the front substrate, so that a transmission axis forms an angle of 45 ° with respect to a direction of alignment treatment of the front substrate;
A rear polarizing plate disposed on the side opposite to the liquid crystal layer side with respect to the rear substrate, so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate;
A front optically anisotropic film disposed between the liquid crystal element and the front polarizing plate,
The negative optical anisotropy has a minimum refractive index in a direction inclined in a specific direction with respect to the normal of the film surface of the front optically anisotropic film,
The angle formed by the direction in which the specific direction is projected onto the film surface and the orientation treatment direction of the front substrate is 0 °.
A front optically anisotropic film;
A rear optically anisotropic film disposed between the liquid crystal element and the rear polarizing plate,
The negative optical anisotropy has a minimum refractive index in the direction inclined in a specific direction with respect to the normal of the film surface of the rear optical anisotropic film,
The angle formed between the direction in which the specific direction is projected onto the film surface and the orientation processing direction of the rear substrate is 0 °.
A rear optically anisotropic film;
A retardation plate disposed between the rear polarizing plate and the rear optically anisotropic film,
The direction having the largest refractive index along the plate surface of the retardation plate, the direction orthogonal to the direction having the largest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s1 axis, f1 axis, And the z1 axis, and the refractive indexes in the directions of the s1 axis, the f1 axis, and the z1 axis are ns1, nf1, and nz1, respectively.
The ns1, the nf1, and the nz1 have a relationship of ns1> nf1 = nz1,
The angle formed between the s1 axis and the transmission axis of the rear polarizing plate is 0 °.
A phase difference plate;
A liquid crystal display element comprising:   The liquid crystal display element according to claim 1, wherein each of the front optical anisotropic film and the rear optical anisotropic film has a discotic liquid crystal. The front substrate and the rear substrate are rectangular,
The angle formed between the direction of the alignment treatment applied to the front substrate and one side of the front substrate is 45 °.
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element. The liquid crystal display element is observed from the front substrate side to the normal direction of the front substrate with respect to the right direction of the horizontal axis extending in the left-right direction of the front substrate as the direction of the alignment treatment applied to the front substrate. Is a direction rotated 45 ° counterclockwise,
The direction of the alignment treatment applied to the rear substrate is determined by observing the liquid crystal display element from the front substrate side to the normal direction of the front substrate with respect to the alignment treatment direction applied to the front substrate. It is a direction rotated 90 ° in the clockwise direction.
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element.   The direction of the transmission axis of the front polarizing plate is counterclockwise by observing the liquid crystal display element from the front substrate side to the normal direction of the front substrate with respect to the direction of alignment treatment applied to the front substrate. 5. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a direction rotated by 45 ° in the direction to be. The value of Δn · d, which is the product of the refractive index anisotropy Δn of the liquid crystal layer and the thickness d of the liquid crystal layer, is 450 nm or more and 550 nm or less,
When the thickness of the retardation plate is d1, the value of (ns1-nf1) d1 relating to the retardation plate is 100 nm or more and 200 nm or less.
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element.   The liquid crystal display element according to claim 6, wherein a value of (ns1−nf1) d1 relating to the retardation plate is approximately 160 nm. A front retardation plate disposed between the front polarizing plate and the front optically anisotropic film,
The direction having the highest refractive index along the plate surface of the front phase difference plate, the direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s2 axis and f2 axis. , And z2 axis, and the refractive indexes in the directions of the s2 axis, the f2 axis, and the z2 axis are ns2, nf2, and nz2, respectively.
The ns2, the nf2, and the nz2 are equal to the ns1, the nf1, and the nz1, respectively.
The angle formed by the s2 axis and the transmission axis of the rear polarizing plate is 0 °.
Further comprising a front retardation plate,
The value of Δn · d, which is the product of the refractive index anisotropy Δn of the liquid crystal layer and the thickness d of the liquid crystal layer, is 450 nm or more and 550 nm or less,
When the thickness of the retardation plate is d1 and the thickness of the front retardation plate is d2, the value of (ns1-nf1) (d1 + d2) relating to the retardation plate and the front retardation plate is 100 nm or more and 200 nm. Is
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element.   9. The liquid crystal display element according to claim 8, wherein a value of (ns1-nf1) d1 relating to the retardation plate and a value of (ns2-nf2) d2 relating to the front retardation plate are both approximately 80 nm. A front substrate and a rear substrate, which have been subjected to alignment treatment in a direction of 90 °, on the surfaces facing each other on which electrodes are formed, and a 90 ° twist of liquid crystal molecules between the front substrate and the rear substrate. A liquid crystal element having a liquid crystal layer provided with twist orientation at corners;
A front polarizing plate disposed on the side opposite to the liquid crystal layer side with respect to the front substrate, so that a transmission axis forms an angle of 45 ° with respect to a direction of alignment treatment of the front substrate;
A rear polarizing plate disposed on the side opposite to the liquid crystal layer side with respect to the rear substrate, so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate;
A front optically anisotropic film disposed between the liquid crystal element and the front polarizing plate,
The negative optical anisotropy has a minimum refractive index in a direction inclined in a specific direction with respect to the normal of the film surface of the front optically anisotropic film,
The angle formed by the direction in which the specific direction is projected onto the film surface and the orientation treatment direction of the front substrate is 0 °.
A front optically anisotropic film;
A rear optically anisotropic film disposed between the liquid crystal element and the rear polarizing plate,
The negative optical anisotropy has a minimum refractive index in the direction inclined in a specific direction with respect to the normal of the film surface of the rear optical anisotropic film,
The angle formed between the direction in which the specific direction is projected onto the film surface and the orientation processing direction of the rear substrate is 0 °.
A rear optically anisotropic film;
A first retardation plate disposed between the front polarizing plate and the front optically anisotropic film,
A direction having the highest refractive index along the plate surface of the first retardation plate, a direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s1 axis, When the refractive indexes in the directions of the f1 axis and the z1 axis and the s1 axis, the f1 axis, and the z1 axis are ns1, nf1, and nz1, respectively,
The ns1, the nf1, and the nz1 have a relationship of ns1> nf1 = nz1,
The angle formed between the s1 axis of the first retardation plate and the optical axis of the front optical anisotropic film is 0 °.
A first retardation plate;
A second retardation plate disposed between the rear polarizing plate and the rear optically anisotropic film,
The direction having the highest refractive index along the plate surface of the second retardation plate, the direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s2 axis, When the refractive indexes in the directions of the f2 axis and the z2 axis and the s2 axis, the f2 axis, and the z2 axis are ns2, nf2, and nz2, respectively.
The ns2, the nf2, and the nz2 have a relationship of ns2> nf2 = nz2,
The angle formed by the s2 axis of the second retardation plate and the optical axis of the rear optical anisotropic film is 0 °.
A second retardation plate;
A third retardation plate disposed between the rear polarizing plate and the second retardation plate,
The direction having the highest refractive index along the plate surface of the third retardation plate, the direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s3 axis, When the refractive indices in the directions of the s3 axis, the f3 axis, and the z3 axis are ns3, nf3, and nz3, respectively, as the f3 axis and the z3 axis,
The ns3, the nf3, and the nz3 have a relationship of ns3> nf3 = nz3,
The angle formed between the s3 axis of the third retardation plate and the transmission axis of the rear polarizing plate is 0 °.
A third retardation plate;
A liquid crystal display element comprising:   The liquid crystal display element according to claim 10, wherein each of the front optical anisotropic film and the rear optical anisotropic film has a discotic liquid crystal. The front substrate and the rear substrate are rectangular,
The angle formed between the direction of the alignment treatment applied to the front substrate and one side of the front substrate is 45 °.
The liquid crystal display element according to claim 10, wherein the liquid crystal display element is a liquid crystal display element. The liquid crystal display element is observed from the front substrate side to the normal direction of the front substrate with respect to the right direction of the horizontal axis extending in the left-right direction of the front substrate as the direction of the alignment treatment applied to the front substrate. Is a direction rotated 45 ° counterclockwise,
The direction of the alignment treatment applied to the rear substrate is determined by observing the liquid crystal display element from the front substrate side to the normal direction of the front substrate with respect to the alignment treatment direction applied to the front substrate. It is a direction rotated 90 ° in the clockwise direction.
The liquid crystal display element according to claim 10, wherein the liquid crystal display element is a liquid crystal display element.   The direction of the transmission axis of the front polarizing plate is counterclockwise by observing the liquid crystal display element from the front substrate side to the normal direction of the front substrate with respect to the direction of alignment treatment applied to the front substrate. The liquid crystal display element according to any one of claims 10 to 13, wherein the liquid crystal display element is a direction rotated by 45 ° in a direction to be. The value of Δn · d, which is the product of the refractive index anisotropy Δn of the liquid crystal layer and the thickness d of the liquid crystal layer, is 350 nm or more and 450 nm or less,
When the thickness of the first retardation plate is d1, the value of (ns1-nf1) d1 relating to the first retardation plate is 15 nm or more and 65 nm or less,
When the thickness of the second retardation plate is d2, the value of (ns2-nf2) d2 regarding the second retardation plate is 15 nm or more and 65 nm or less,
When the thickness of the third retardation plate is d3, the value of (ns3-nf3) d3 regarding the third retardation plate is 80 nm or more and 180 nm or less.
The liquid crystal display element according to claim 10, wherein the liquid crystal display element is a liquid crystal display element. The value of (ns1-nf1) d1 for the first retardation plate is approximately 45 nm,
The value of (ns2-nf2) d2 for the second retardation plate is approximately 45 nm,
The value of (ns3-nf3) d3 for the third retardation plate is approximately 140 nm.
The liquid crystal display element according to claim 15. A fourth retardation plate disposed between the front polarizing plate and the first retardation plate,
The direction with the highest refractive index along the plate surface of the fourth retardation plate, the direction orthogonal to the direction with the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively s4 axis, When the refractive index in the directions of the f4 axis and the z4 axis and the s4 axis, the f4 axis, and the z4 axis are ns4, nf4, and nz4, respectively,
The ns4, the nf4, and the nz4 are equal to the ns3, the nf3, and the nz3, respectively.
The angle formed between the s4 axis of the fourth retardation plate and the transmission axis of the rear polarizing plate is 0 °.
A fourth retardation plate;
The value of Δn · d, which is the product of the refractive index anisotropy Δn of the liquid crystal layer and the thickness d of the liquid crystal layer, is 350 nm or more and 450 nm or less,
When the thickness of the first retardation plate is d1, the value of (ns1-nf1) d1 relating to the first retardation plate is 15 nm or more and 65 nm or less,
When the thickness of the second retardation plate is d2, the value of (ns2-nf2) d2 regarding the second retardation plate is 15 nm or more and 65 nm or less,
When the thickness of the third retardation plate is d3 and the thickness of the fourth retardation plate is d4, the third retardation plate and the fourth retardation plate are related to (ns3-nf3). ) The value of (d3 + d4) is not less than 80 nm and not more than 180 nm.
The liquid crystal display element according to claim 10, wherein the liquid crystal display element is a liquid crystal display element.   The value of (ns3-nf3) d3 relating to the third retardation plate and the value of (ns4-nf4) d4 relating to the fourth retardation plate are both approximately 70 nm. Liquid crystal display element. A front substrate and a rear substrate, which have been subjected to alignment treatment in a direction of 90 °, on the surfaces facing each other on which electrodes are formed, and a 90 ° twist of liquid crystal molecules between the front substrate and the rear substrate. A liquid crystal element having a liquid crystal layer provided in a twist orientation at a corner; a front polarizing plate disposed on a side opposite to the liquid crystal layer side with respect to the front substrate; and a liquid crystal layer side with respect to the rear substrate; Is a rear polarizing plate arranged on the opposite side so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate,
Determine the angle formed by the direction of the alignment treatment of the front substrate and the transmission axis of the front polarizing plate,
A front optical anisotropic film having a negative optical anisotropy that is disposed between the liquid crystal element and the front polarizing plate and has a minimum refractive index in a direction inclined in a specific direction with respect to the normal of the film surface And a rear optical element having a negative optical anisotropy that is disposed between the liquid crystal element and the rear polarizing plate and has a minimum refractive index in a direction tilted in a specific direction with respect to the normal of the film surface With anisotropic film,
An angle formed by an orientation treatment direction of the front substrate and a direction in which a specific direction of the front optical anisotropic film is projected onto the film surface of the front optical anisotropic film;
An angle formed between the orientation treatment direction of the rear substrate and the direction in which the specific direction of the rear optical anisotropic film is projected onto the film surface of the rear optical anisotropic film;
Is determined so that the maximum value of the brightness displayed on the liquid crystal display element when a sufficiently strong electric field is formed between the front substrate and the rear substrate is minimized,
In the phase difference plate disposed between at least one of the front polarizing plate and the front optical anisotropic film and between the rear polarizing plate and the rear optical anisotropic film,
The direction with the highest refractive index along the plate surface of the retardation plate, the direction orthogonal to the direction with the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented as s-axis, f-axis, And the z-axis, and the refractive indexes in the directions of the s-axis, the f-axis, and the z-axis are ns, nf, and nz, respectively.
An angle formed by the transmission axis of the rear polarizing plate and the s-axis of the retardation plate;
A combination of the ns, the nf, the nz, and the thickness of the retardation plate;
Is determined so that the maximum value of the luminance displayed on the liquid crystal display element when a sufficiently strong electric field is formed between the front substrate and the rear substrate is minimized.
An optical compensation method for a liquid crystal display element. A front substrate and a rear substrate, which have been subjected to alignment treatment in a direction of 90 °, on the surfaces facing each other on which electrodes are formed, and a 90 ° twist of liquid crystal molecules between the front substrate and the rear substrate. A liquid crystal element having a liquid crystal layer provided in a twist orientation at a corner; a front polarizing plate disposed on a side opposite to the liquid crystal layer side with respect to the front substrate; and a liquid crystal layer side with respect to the rear substrate; Is a rear polarizing plate arranged on the opposite side so that the transmission axis forms an angle of 90 ° with respect to the transmission axis of the front polarizing plate,
Determine the angle formed by the direction of the alignment treatment of the front substrate of the liquid crystal element and the transmission axis of the front polarizing plate,
A front optical anisotropic film having a negative optical anisotropy that is disposed between the liquid crystal element and the front polarizing plate and has a minimum refractive index in a direction inclined in a specific direction with respect to the normal of the film surface And a rear optical element having a negative optical anisotropy that is disposed between the liquid crystal element and the rear polarizing plate and has a minimum refractive index in a direction tilted in a specific direction with respect to the normal of the film surface With anisotropic film,
An angle formed by an orientation treatment direction of the front substrate and a direction in which a specific direction of the front optical anisotropic film is projected onto the film surface of the front optical anisotropic film;
An angle formed between the orientation treatment direction of the rear substrate and the direction in which the specific direction of the rear optical anisotropic film is projected onto the film surface of the rear optical anisotropic film;
Is determined so that the maximum value of the brightness displayed on the liquid crystal display element when a sufficiently strong electric field is formed between the front substrate and the rear substrate is minimized,
A first retardation plate disposed between the front polarizing plate and the front optical anisotropic film, and a second retardation disposed between the rear polarizing plate and the rear optical anisotropic film. In the phase difference plate of
The direction having the highest refractive index along the plate surface of the first retardation plate, the direction orthogonal to the direction having the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented by s1 axis, The refractive indexes in the directions of the s1 axis, the f1 axis, and the z1 axis are ns1, nf1, and nz1, respectively, and are most refracted along the plate surface of the second retardation plate. The direction in which the refractive index is large, the direction orthogonal to the direction having the largest refractive index along the plate surface, and the normal direction of the plate surface are the s2 axis, the f2 axis, and the z2 axis, respectively. , And the refractive index in the direction of the z2 axis are ns2, nf2, and nz2, respectively.
An angle formed by the transmission axis of the front polarizing plate and the s1 axis of the first retardation plate,
A combination of the ns1, the nf1, the nz1, and the thickness d1 of the first retardation plate;
An angle formed by the transmission axis of the front polarizing plate and the s2 axis of the second retardation plate,
A combination of the ns2, the nf2, the nz2, and the thickness d2 of the second retardation plate;
Is determined so that the minimum value of luminance displayed on the liquid crystal display element when an electric field is not formed between the front substrate and the rear substrate is maximized,
In the retardation plate disposed between at least one of the front polarizing plate and the first retardation plate and between the rear polarizing plate and the second retardation plate,
The direction with the highest refractive index along the plate surface of the retardation plate, the direction orthogonal to the direction with the highest refractive index along the plate surface, and the normal direction of the plate surface are respectively represented as s-axis, f-axis, And the z-axis, and the refractive indexes in the directions of the s-axis, the f-axis, and the z-axis are ns, nf, and nz, respectively.
An angle formed by the transmission axis of the rear polarizing plate and the s-axis of the retardation plate;
A combination of the ns, the nf, the nz, and the thickness of the retardation plate;
Is determined so that the maximum value of the luminance displayed on the liquid crystal display element when a sufficiently strong electric field is formed between the front substrate and the rear substrate is minimized.
An optical compensation method for a liquid crystal display element.

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