JP4441971B2 - Liquid crystal display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called in-plane switching mode liquid crystal display element that displays an image by forming an electric field in a direction parallel to a substrate between a pixel electrode and a common electrode.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a so-called in-plane switching mode liquid crystal display element that displays an image by forming an electric field in a direction parallel to a substrate between a pixel electrode and a common electrode has been proposed. This in-plane switching mode is known to provide a wider viewing angle than the TN mode.
[0003]
Such a liquid crystal display element includes a pair of substrates, a liquid crystal layer provided between the substrates, first and second polarizing plates disposed between the substrates, and the polarizing plate and each substrate. The first and second retardation plates are provided between the first and second retardation plates.
[0004]
In this liquid crystal display element, the alignment direction of the polarizing plate and the liquid crystal layer is set so that the initial alignment is set to black display when no voltage is applied between the electrodes. The orientation direction of the layers is generally rotated by 45 ° to display white.
[0005]
The director distribution in the liquid crystal layer in white display is twisted, but optically functions as a λ / 2 plate (half-wave plate). The director distribution is twisted when the director near the substrate does not move much. When functioning as a λ / 2 plate, the maximum transmittance is obtained when the effective retardation (Δnd) is λ / 2 in the 45 ° orientation.
[0006]
[Problems to be solved by the invention]
By the way, in the liquid crystal display element as described above, for example, when the retardation (Δnd) is λ / 2 at a wavelength of 550 nm, as shown in FIG. 33, it functions as a λ / 2 plate. In the vicinity of the wavelength of 550 nm and at a wavelength distance from 550 nm, the transmittance decreases. That is, since the transmittance T is expressed by the following equation, the transmittance T is reduced except for a predetermined wavelength.
[0007]
T = sin2π (Δnd / λ)
Further, due to the twist of the director distribution in the liquid crystal layer in the white display, the transmittance T is further reduced as shown in the following formula, particularly in a low voltage state (sin 22φ corresponds to the influence of the twist of the director distribution). .
[0008]
T = sin22φsin2π (Δnd / λ)
In the halftone, as shown in FIG. 34, when the voltage is changed, the reversal of the transmittance occurs at the wavelength on the blue side (band of about 460 nm or less).
[0009]
Furthermore, as shown in FIGS. 35 to 38, when the viewing angle is large, chromaticity change occurs. FIGS. 35 to 38 show changes in chromaticity when the viewing angle is changed from 0 ° to 80 ° for azimuth angles of 0 ° (horizontal), 45 °, 90 ° (vertical), and 135 °, respectively. ing. It can be seen that for azimuth angles of 45 ° and 135 °, a considerably large change in chromaticity occurs. In obtaining the data shown in FIGS. 35 to 38, “Nitto Denko G1220DU” is used as a polarizing plate, and a C light source is used as a light source.
[0010]
Therefore, the present invention has been proposed in view of the above-described circumstances, has a good spectral transmittance, does not cause a reversal of transmittance even in a halftone display, and has a large viewing angle. The liquid crystal display element which can suppress the chromaticity change of this and can perform image display by favorable contrast is intended to be provided.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, a liquid crystal display element according to the present invention includes a pair of substrates, at least one of which is transparent, a pixel electrode group, and a common electrode group. An electrode group for forming a pixel region, a liquid crystal layer provided between the substrates, first and second polarizing plates disposed between the substrates, and the first polarizing plate and each substrate. A first retardation plate disposed between the second polarizing plate and a second retardation plate disposed between each substrate and the first and second retardation plates; the above liquid crystal layer, in which retardation displays an image by equal to each other, the electric field in the direction parallel to the substrate between the pixel electrode and the common electrode through the electrode group is formed.
[0012]
In this liquid crystal display element, with reference to the orientation of the first polarizing plate, the angle formed by the slow axis of the first retardation plate is θ1, the angle formed by the slow axis of the liquid crystal layer is θ2, and the above The angle formed by the slow axis of the second retardation plate is θ3, and for the birefringence of the retardation plate, the slow axis refractive index is ns, the fast axis refractive index is nf, and the refractive index in the thickness direction is nz. When (ns−nz) / (ns−nf) ≦ 0.5θ1 = θ3 holds, when the display element is at the white level , θ2 = 2 × θ1 + 45 ° holds, and when the display element is at the black level , Θ2 = 2 × θ1 + 90 ° is satisfied.
[0013]
In the liquid crystal display element according to the present invention, (ns−nz) / (ns−nf) ≦ 0.5θ3 = 0 ° is established , and θ2 = θ1 + 45 ° is established when the display element is at the white level. When the display element is at a black level, the condition of θ2 = θ1 + 90 ° is satisfied.
[0014]
Further, in the liquid crystal display element according to the present invention, (ns−nz) / (ns−nf) ≦ 0.5θ3 = 90 ° is established , and θ2 = θ1 + 45 ° is established when the display element is at the white level. When the display element is at a black level, the condition of θ2 = θ1 + 90 ° is satisfied.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
As shown in FIG. 1, the liquid crystal display element according to the present invention includes a liquid crystal layer 1, first and second retardation plates 2 and 3 that form a pair sandwiching the liquid crystal layer 1, and these retardation plates. An incident polarizing plate 4 and an output polarizing plate 5 which are first and second polarizing plates sandwiching 2 and 3 are provided.
[0018]
In this liquid crystal display element, the liquid crystal layer 1 is provided between a pair of substrates (not shown). At least one of these substrates is formed to be transparent. The substrate is provided with an electrode group including a pixel electrode group and a common electrode group. In this electrode group, pixel regions are formed in a matrix on the substrate by each pixel electrode and each common electrode. The liquid crystal display element is a so-called in-plane switching mode liquid crystal display element that performs image display by forming an electric field in a direction parallel to the substrate between the pixel electrode and the common electrode.
[0019]
In this liquid crystal display element, the incident polarizing plate 4 and the outgoing polarizing plate 5 are arranged in a crossed Nicols relationship. The orientation directions of the polarizing plates 4 and 5 and the liquid crystal layer 1 are set so that the initial orientation is black when no voltage is applied between the pixel electrode and the common electrode, and an electric field is applied. Sometimes, the alignment direction of the liquid crystal layer 1 is rotated by 45 ° to display white. The director distribution in the liquid crystal layer 1 in white display is twisted due to the fact that the director in the vicinity of the substrate does not move so much, but optically functions as a λ / 2 plate (half-wave plate). When the liquid crystal layer 1 functions as a λ / 2 plate, the maximum transmittance is obtained when the effective retardation (Δnd) is λ / 2 in a 45 ° orientation.
[0020]
[First Embodiment]
Using the transmission axis of the incident polarizing plate 4 as a reference, the slow axis directions of the phase difference plates 2 and 3 are θ1 and θ3, the director direction at the black level of the liquid crystal layer 1 (when no voltage is applied to the electrode group), θ2B, and white The director direction at the level (when voltage is applied to the electrode group) is θ2W. Then, in this liquid crystal display element, the following relationship is established.
[0021]
θ1 = θ3
θ2B = θ1 × 2 + 90 °
θ2W = θ1 × 2 + 45 °
Here, when θ1 = θ3 = 15 °, θ2B = 120 ° and θ2W = 75 °. In this liquid crystal display element, when the retardation (Δnd) at a wavelength of 550 nm is 275 nm for both the liquid crystal layer 1 and the phase difference plates 2 and 3, the spectral transmittance of the black level and the white level is as shown in FIG. It shows a flat characteristic over a wide wavelength band. Here, as the retardation plates 2 and 3, a stretched polycarbonate film was used.
[0022]
The retardation (Δnd) of the phase difference plates 2 and 3 is set to be approximately equal to the retardation (Δnd) of the liquid crystal layer 1. When the retardation (Δnd) between the phase difference plates 2 and 3 and the liquid crystal layer 1 is shifted, the black level transmittance increases as shown in FIG. FIG. 3 shows the spectral transmittance of the black level when only the retardation (Δnd) of the liquid crystal layer 1 is changed. That is, the spectral transmittance of the black level when the ratio of the retardation (Δnd) of the liquid crystal layer 1 to the retardation (Δnd) of the retardation films 2 and 3 is changed in the range of 0.67 to 1.33. .
[0023]
The value of retardation (Δnd) affects the white level as shown in FIG. FIG. 4 shows a white level spectrum when the retardation (Δnd) of the phase difference plates 2 and 3 is changed while the retardation (Δnd) of the liquid crystal layer 1 and the phase difference plates 2 and 3 are kept equal. The transmittance is shown.
[0024]
In order to make the white level spectral transmittance flatter, the retardation (Δnd) is preferably in the range of about 200 nm to 300 nm at a wavelength of 550 nm. However, this value should be adjusted according to the wavelength band to be flattened.
[0025]
The alignment directions of the phase difference plates 2 and 3 and the liquid crystal layer 1 preferably satisfy the above relational expression and are in a range of 0 ° <θ1 ≦ 30 °. When θ1 is changed, the spectral transmittance of the white level changes as shown in FIG.
[0026]
In this liquid crystal display element, halftone display is not completely compensated, but as compared with the conventional product, as shown in FIG. 6, the spectral transmittance when the voltage is changed is improved. It is done. That is, the transmittance reversal phenomenon does not occur in the blue wavelength band.
[0027]
As for the angle setting, the same result can be obtained using the absorption axis of the incident polarizing plate 4 as a reference.
[0028]
Next, regarding the viewing angle, if a uniaxial one is used as the phase difference plates 2 and 3, the phase difference changes as the viewing angle increases. When the phase difference changes, the black level rises as shown in FIG. Also, the white level changes as shown in FIG. FIG. 7 shows the 550 nm wavelength at azimuth angles of 0 ° (horizontal), 45 °, 90 ° (vertical), and 135 ° with respect to the black level and the white level at a wavelength of 550 nm when a uniaxial retardation plate is used. The characteristic with respect to the viewing angle of the transmittance | permeability is shown. In addition, “Nitto Denko G1220DU” was used as the polarizing plate.
[0029]
In the liquid crystal display element according to the present invention, a biaxial retardation plate is used in order to improve the characteristics with respect to such a viewing angle. That is, the following conditions are satisfied, assuming that the refractive index in the thickness direction is nz, the slow axis refractive index is ns, and the fast axis refractive index is nf.
[0030]
(Ns-nz) / (ns-nf) = 0.5
When this condition is satisfied, the phase difference is compensated as shown in FIG. 8 even when the viewing angle is increased. The fact that this condition is satisfied corresponds to the retardation plate being biaxial, and the value of 1 corresponds to the retardation plate being uniaxial. FIG. 8 shows an azimuth angle of 0 ° (horizontal), 45 °, and 90 ° (vertical) with respect to the black level and the white level at a wavelength of 550 nm when a biaxial retardation plate satisfying this condition is used. , Shows the characteristics of the transmittance with respect to the viewing angle at a wavelength of 550 nm at 135 °. In addition, when this condition is satisfied, the change in chromaticity when the viewing angle changes is extremely small as shown in FIGS. 9 to 12 show changes in chromaticity when the viewing angle is changed from 0 ° to 80 ° for azimuth angles of 0 ° (horizontal), 45 °, 90 ° (vertical), and 135 °, respectively. ing. In addition, “Nitto Denko G1220DU” was used as the polarizing plate.
[0031]
[Second Embodiment]
In this liquid crystal display element, it is desirable that the following conditions are satisfied in order to further improve the black level characteristics.
[0032]
(Ns-nz) / (ns-nf) <0.5
In addition, since a voltage cannot be sufficiently applied in a general IPS, the effective retardation (Δnd) is reduced to about 80% of the black level at the white level, and the effective orientation change is about 30 °. . In this state, it is desirable that the following condition is satisfied even at the white level.
[0033]
(Ns-nz) / (ns-nf) <0.5
Here, it is assumed that the following conditions are satisfied with the same configuration as the first embodiment.
[0034]
(Ns-nz) / (ns-nf) = 0.2
In this case, as shown in the “equal contrast controller diagram” of FIG. 13 and the “equal color difference controller diagram of white level” in FIG. 14, the “equal contrast controller diagram” of the conventional liquid crystal display element in FIG. It can be seen that the viewing angle is wider than the “white level equal color difference controller diagram” of the conventional liquid crystal display element of FIG. Here, the “isocontrast controller diagram” indicates a range where the contrast is 100: 1 or more. Further, the “equal color difference contour diagram” shows a range in which the color difference is within 5 jnd in the L * u * V * color system.
[0035]
[Third Embodiment]
In this embodiment, as shown in FIG. 17, one first retardation plate 2 is arranged on one side of the liquid crystal layer 1 for the purpose of improving the spectral transmittance of the white level. The second retardation plate 3 is for compensating the viewing angle. As shown in FIG. 17, the phase difference plates 2 and 3 are arranged in such a way that one plate is disposed on each side, and two are disposed on one side of the liquid crystal layer 1 as shown in FIG. It is done.
[0036]
The angle between the slow axis of the first retardation plate 2 and the transmission axis of the incident polarizing plate 4 is θ1, the angle between the slow axis of the second retardation plate 3 and the transmission axis of the incident polarizing plate 4 is θ3, The director orientation of the liquid crystal layer 1 is θ2B at the black level (generally when no voltage is applied) and θ2W at the white level. Here, the following conditions are satisfied.
[0037]
θ2B = θ1 + 90 °
θ2W = θ1 + 45 °
Therefore, when θ1 = 22.5 °, θ2B = 112.5 ° and θ2W = 67.5 °. When the retardation (Δnd) is 275 nm for both the liquid crystal layer 1 and the retardation plates 2 and 3 at a wavelength of 550 nm, the spectral transmittance of the black level and the white level is substantially flat as shown in FIG. It has become. In addition, as the retardation plates 2 and 3, a stretched polycarbonate film was used.
[0038]
In this embodiment, the retardation (Δnd) of the phase difference plates 2 and 3 is set to be approximately equal to the retardation (Δnd) of the liquid crystal layer 1 as in the first embodiment. When the retardation (Δnd) between the phase difference plates 2 and 3 and the liquid crystal layer 1 is shifted, the black level transmittance increases as shown in FIG. FIG. 20 shows the spectral transmittance of the black level when only the retardation (Δnd) of the liquid crystal layer 1 is changed. The retardation of the retardation plates 2 and 3 of the retardation (Δnd) of the liquid crystal layer 1 is shown. This is when the ratio to (Δnd) is changed in the range of 0.67 to 1.33. Here, θ1 = 22.5 °, θ2B = 112.5 °, and θ2W = 67.5 °.
[0039]
The retardation (Δnd) value also affects the white level as shown in FIG. FIG. 21 shows the spectral transmittance of the white level when the retardation (Δnd) of the phase difference plates 2 and 3 is changed to be equal to the retardation (Δnd) of the liquid crystal layer 1. Here, θ1 = 22.5 °, θ2B = 112.5 °, and θ2W = 67.5 °. In order to flatten the spectral transmittance of the white level, the retardation (Δnd) is preferably in the range of about 200 nm to 300 nm at a wavelength of 550 nm, but should be adjusted according to the wavelength band to be flattened.
[0040]
The alignment directions of the phase difference plates 2 and 3 and the liquid crystal layer 1 preferably satisfy the above relational expression and are in the range of 0 <θ1 ≦ 30 °. When θ1 is changed, the spectral transmittance of the white level changes as shown in FIG. 22, but here, the case of θ1 = 22.5 ° shows the flattest characteristics. Here, the retardation (Δnd) is 275 nm for both the liquid crystal layer 1 and the phase difference plates 2 and 3 at a wavelength of 550 nm.
[0041]
Incidentally, in this liquid crystal display element, the second retardation plate 3 is used as shown in FIG. 17 in order to improve the viewing angle characteristics. As in the first embodiment, it is assumed that the following conditions are satisfied for the refractive index of the retardation plate.
[0042]
(Ns-nz) / (ns-nf) = 0.5
Then, θ3 = 0 °. In this case, as shown in FIG. 23, the transmittance viewing angle characteristics with respect to the azimuth angles 0 °, 45 °, 90 °, and 135 ° of the black level and the white level at a wavelength of 550 nm are good. Further, the change in chromaticity depending on the viewing angle also has good characteristics as shown in FIGS. 24 to 27 show changes in chromaticity when the viewing angle is changed from 0 ° to 80 ° for azimuth angles of 0 ° (horizontal), 45 °, 90 ° (vertical), and 135 °, respectively. ing. Again, Nitto Denko G1220DU was used as the polarizing plate.
[0043]
Further, as shown in FIG. 18, when the first and second retardation plates 2 and 3 are arranged on one side of the liquid crystal layer 1, θ3 = 90 °. In this case, as shown in FIG. 28, the transmittance viewing angle characteristics for the azimuth angles 0 °, 45 °, 90 °, and 135 ° of the black level and the white level at a wavelength of 550 nm are good. Further, the change in chromaticity depending on the viewing angle also has good characteristics as shown in FIGS. These FIG. 29 to FIG. 32 show changes in chromaticity when the viewing angle is changed from 0 ° to 80 ° for azimuth angles of 0 ° (horizontal), 45 °, 90 ° (vertical), and 135 °, respectively. ing. Again, Nitto Denko G1220DU was used as the polarizing plate.
[0044]
【The invention's effect】
As described above, the liquid crystal display element according to the present invention is a so-called in-plane switching mode liquid crystal display element, and a biaxial one is used as a retardation plate disposed on both sides or one side of the liquid crystal layer. Thus, the spectral transmittance is improved, the reverse phenomenon of the transmittance in halftone display is prevented, the chromaticity change is suppressed at a large viewing angle, and the contrast is improved.
[0045]
That is, according to the present invention, the spectral transmittance is good, the inversion phenomenon of the transmittance does not occur even in the halftone display, the chromaticity change at a large viewing angle is suppressed, and the image is displayed with a good contrast. It is possible to provide a liquid crystal display element capable of performing the above.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a liquid crystal display element according to the present invention in first and second embodiments.
FIG. 2 is a graph showing spectral characteristics of a black level and a white level of the liquid crystal display element.
FIG. 3 is a graph showing the spectral characteristics of black level when the retardation of the liquid crystal layer is shifted in the liquid crystal display element.
FIG. 4 is a graph showing the influence of retardation value on spectral characteristics of white level in the liquid crystal display element.
FIG. 5 is a graph showing the influence of the change in the slow axis direction of the retardation plate in the liquid crystal display element on the spectral characteristics of the white level.
FIG. 6 is a graph showing spectral transmittance for halftone display in the liquid crystal display element.
FIG. 7 is a graph showing a change in black level with respect to a viewing angle when a uniaxial retardation plate is used in a liquid crystal display element.
FIG. 8 is a graph showing a change in white level with respect to a viewing angle when a uniaxial retardation plate is used in a liquid crystal display element.
FIG. 9 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 0 ° (horizontal) in the liquid crystal display element according to the present invention.
FIG. 10 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 45 ° in the liquid crystal display element.
FIG. 11 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 90 ° (vertical) in the liquid crystal display element.
FIG. 12 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° with respect to an azimuth angle of 135 ° in the liquid crystal display element.
FIG. 13 is an iso-contrast contour diagram in the liquid crystal display element.
FIG. 14 is a white level equal color difference contour diagram in the liquid crystal display element.
FIG. 15 is an iso-contrast contour diagram in a conventional liquid crystal display element.
FIG. 16 is a white level equal color difference contour diagram in the conventional liquid crystal display device.
FIG. 17 is a perspective view showing a configuration in which retardation plates are arranged on both sides of a liquid crystal layer in a third embodiment of a liquid crystal display element according to the present invention.
FIG. 18 is a perspective view showing a configuration in which a retardation plate is arranged on one side of a liquid crystal layer in the third embodiment of the liquid crystal display element.
FIG. 19 is a graph showing spectral characteristics of a black level and a white level of the liquid crystal display element.
FIG. 20 is a graph showing the spectral characteristics of the black level when the retardation of the liquid crystal layer is shifted in the liquid crystal display element.
FIG. 21 is a graph showing the influence of the retardation value on the spectral characteristics of the white level in the liquid crystal display element.
FIG. 22 is a graph showing the influence of the change in the slow axis direction of the retardation plate in the liquid crystal display element on the spectral characteristics of the white level.
FIG. 23 is a graph showing changes in white level and black level with respect to a viewing angle when θ3 = 0 ° in the liquid crystal display element.
FIG. 24 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 0 ° (horizontal) in the liquid crystal display element.
FIG. 25 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 45 ° in the liquid crystal display element.
FIG. 26 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 90 ° (vertical) in the liquid crystal display element.
FIG. 27 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° with respect to an azimuth angle of 135 ° in the liquid crystal display element.
FIG. 28 is a graph showing changes in white level and black level with respect to a viewing angle when θ3 = 90 ° in the liquid crystal display element.
FIG. 29 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 0 ° (horizontal) in the liquid crystal display element.
FIG. 30 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 45 ° in the liquid crystal display element.
FIG. 31 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 90 ° (vertical) in the liquid crystal display element.
FIG. 32 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° with respect to an azimuth angle of 135 ° in the liquid crystal display element.
FIG. 33 is a graph showing spectral characteristics of a black level and a white level in a conventional liquid crystal display element.
FIG. 34 is a graph showing spectral transmittance for halftone display in the conventional liquid crystal display element.
FIG. 35 is a chromaticity diagram showing changes in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 0 ° (horizontal) in the conventional liquid crystal display device.
FIG. 36 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 45 ° in the conventional liquid crystal display element.
FIG. 37 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° at an azimuth angle of 90 ° (vertical) in the conventional liquid crystal display device.
FIG. 38 is a chromaticity diagram showing a change in chromaticity when the viewing angle is changed from 0 ° to 80 ° with an azimuth angle of 135 ° in the conventional liquid crystal display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal layer, 2 1st phase difference plate, 2nd phase difference plate, 4 Incident polarizing plate, 5
Output polarizing plate

Claims (3)

A pair of substrates at least one of which is transparent;
An electrode group comprising a pixel electrode group and a common electrode group, each pixel electrode and the common electrode forming a pixel region in a matrix on the substrate;
A liquid crystal layer provided between the substrates,
A first polarizing plate and a second polarizing plate disposed across the substrates;
A first retardation plate disposed between the first polarizing plate and each of the substrates;
A second retardation plate disposed between the second polarizing plate and each of the substrates,
It said the first and second phase difference plate and the liquid crystal layer, the retardation is equal to each other,
With reference to the orientation of the first polarizer, the angle formed by the slow axis of the first retardation plate is θ1, the angle formed by the slow axis of the liquid crystal layer is θ2, and the second retardation plate When the angle formed by the slow axis is θ3,
θ1 = θ3
When the display element is at the white level ,
θ2 = 2xθ1 + 45 °
When the display element is at the black level,
θ2 = 2xθ1 + 90 °
Further, for the birefringence of the retardation plate, when the slow axis refractive index is ns, the fast axis refractive index is nf, and the refractive index in the thickness direction is nz,
(Ns-nz) / (ns-nf) ≦ 0.5
Is satisfied,
A liquid crystal display element that displays an image by forming an electric field in a direction parallel to the substrate between the pixel electrode and the common electrode through the electrode group. A pair of substrates at least one of which is transparent;
An electrode group comprising a pixel electrode group and a common electrode group, each pixel electrode and the common electrode forming a pixel region in a matrix on the substrate;
A liquid crystal layer provided between the substrates,
A first polarizing plate and a second polarizing plate disposed across the substrates;
A first retardation plate disposed between the first polarizing plate and each of the substrates;
A second retardation plate disposed between the second polarizing plate and each of the substrates,
It said the first and second phase difference plate and the liquid crystal layer, the retardation is equal to each other,
With reference to the orientation of the first polarizer, the angle formed by the slow axis of the first retardation plate is θ1, the angle formed by the slow axis of the liquid crystal layer is θ2, and the second retardation plate When the angle formed by the slow axis is θ3,
θ3 = 0 °
When the display element is at the white level ,
θ2 = θ1 + 45 °
When the display element is at the black level,
θ2 = θ1 + 90 °
Further, for the birefringence of the retardation plate, when the slow axis refractive index is ns, the fast axis refractive index is nf, and the refractive index in the thickness direction is nz,
(Ns-nz) / (ns-nf) ≦ 0.5
Is satisfied,
A liquid crystal display element, wherein an image is displayed by forming an electric field in a direction parallel to the substrate between the pixel electrode and the common electrode through the electrode group. A pair of substrates at least one of which is transparent;
An electrode group comprising a pixel electrode group and a common electrode group, each pixel electrode and the common electrode forming a pixel region in a matrix on the substrate;
A liquid crystal layer provided between the substrates,
A first polarizing plate and a second polarizing plate disposed across the substrates;
A first retardation plate and a second retardation plate disposed between the first polarizing plate and each of the substrates ;
With
It said the first and second phase difference plate and the liquid crystal layer, the retardation is equal to each other,
Using the orientation of the first polarizing plate as a reference, the angle formed by the slow axis of the first retardation plate is θ1, the angle formed by the slow axis of the liquid crystal layer is θ2, and the second retardation plate When the angle formed by the slow axis is θ3,
θ3 = 90 °
When the display element is at the white level ,
θ2 = θ1 + 45 °
When the display element is at the black level,
θ2 = θ1 + 90 °
Further, for the birefringence of the retardation plate, when the slow axis refractive index is ns, the fast axis refractive index is nf, and the refractive index in the thickness direction is nz,
(Ns-nz) / (ns-nf) ≦ 0.5
Is satisfied,
A liquid crystal display element that displays an image by forming an electric field in a direction parallel to the substrate between the pixel electrode and the common electrode through the electrode group.

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