JP3070181B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in viewing angle characteristics of a twisted nematic liquid crystal display.

[0002]

2. Description of the Related Art A liquid crystal display device has a simple matrix type in which a plurality of stripe-shaped electrodes facing each other via a liquid crystal are arranged so as to intersect with each other, and a plurality of pixels are formed at a plurality of intersections. There has been proposed an active matrix type in which a plurality of pixel electrodes each connected to a driving thin film transistor are provided, and a plurality of pixels are formed at a portion where the pixel electrode and a counter electrode face each other. Among these liquid crystal display devices, a twisted nematic type (hereinafter, referred to as TN) liquid crystal display device having a thin film transistor (hereinafter, referred to as TFT) is used for a display such as a word processor or a personal computer. A TN type liquid crystal display device (hereinafter referred to as a TFT-LCD) provided with the TFT includes a TN liquid crystal cell provided with a driving TFT for each pixel electrode and a TN liquid crystal cell having a transmission axis of a substrate on the light incident side of the liquid crystal cell. A polarizer disposed on the light incident side of the liquid crystal cell so as to be parallel to the rubbing direction, and an analyzer disposed on the light exit side of the liquid crystal cell such that the transmission axis is substantially orthogonal to the transmission axis of the polarizer. It is composed of Since this conventional TFT-LCD can be driven statically, it has a high contrast and a relatively wide viewing angle.

FIG. 12 shows a viewing angle characteristic of such a conventional liquid crystal display device, FIG. 13 shows a voltage-luminance characteristic thereof, and FIG. 14 shows a change in display color. This FIG.
Indicates an iso-contrast curve, in which five concentric circles are inclined from the inside toward the outside at angles of 10 °, 20 °, 30 °, 40 °, and 50 ° with respect to the normal line of the liquid crystal display device. Indicates the direction. In addition, this isocontrast curve is based on the rubbing direction A of the substrate on the incident light side of the liquid crystal cell as a reference (0 °), and the clockwise direction (leftward in the figure) as viewed from the incident light side of the liquid crystal cell is positive. It represents the observed contrast. The dotted line indicates that the contrast is 10
0 indicates the contrast, the one-dot chain line indicates the contrast of 50, the solid line indicates the contrast of 10, and the two-dot chain line indicates that the contrast is less than 1, that is, the display brightness is reversed. In measuring the contrast, a C light source is used, and the value of the contrast is defined by the ratio of the Y value of the transmitted light.
The front contrast was set to about 100.

As shown by the isocontrast curve, in the conventional liquid crystal display device, the direction in which a high contrast is obtained (viewing angle direction) is 315 ° from the rubbing direction of the alignment film formed on the light incident side substrate. V. Therefore, in the TFT-LCD, the direction V is made to coincide with the vertical direction of the liquid crystal cell. This TFT-LCD has a relatively large area of contrast 50 or more surrounded by a dashed line,
Further, the region surrounded by the solid line and having a contrast of 10 or more is relatively wide, and has a better viewing angle characteristic than the conventional simple matrix type liquid crystal display device.

[0005]

However, in the above-mentioned conventional liquid crystal display device, as shown in FIG. 12, the display device has a relatively wide viewing angle in the left-right direction, but has a relatively wide viewing angle in the vertical direction. There was a disadvantage that it was narrow. Further, in the conventional liquid crystal display device, as shown in FIG. 12, a region having a contrast of less than 1 surrounded by a two-dot chain line exists in a relatively wide range in a direction in which the liquid crystal display device is observed from above. The region where the contrast is less than 1 is a region where the brightness of a displayed image is reversed (hereinafter, referred to as a reversed region). With this reversal area, it is 40 ° above the front of the liquid crystal display device.
When viewed from a direction inclined by about 50 °, the image looks like a negative image in which the density of the image is inverted, and the display quality of the liquid crystal display device is significantly reduced. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device capable of improving a viewing angle.

[0006]

In order to achieve the above object, the present invention provides a liquid crystal material filled between a pair of substrates.
The crystal molecules are twisted by almost 90 ° to form an aligned liquid crystal layer.
And a twisted nematic liquid crystal cell sandwiched between the pair of substrates , and disposed on the incident light side of the liquid crystal cell, and the polarization axis thereof is orthogonal to the alignment processing direction on the incident light side of the liquid crystal cell. Or the first oriented parallel
A polarizing plate; a first phase plate disposed between the first polarizing plate and the liquid crystal cell; and a polarizing axis disposed on an emission light side of the liquid crystal cell and having a polarization axis of the first polarizing plate. And a second phase plate disposed between the second polarizer and the liquid crystal cell, wherein the first phase plate and the second phase plate are respectively retarded. A phase axis or a fast axis orthogonal thereto is arranged in a direction substantially coincident with the directions of the respective polarization axes of the adjacent first polarizing plate and the second polarizing plate.

[0007]

According to the present invention, the liquid crystal cell and the first light on the incident light side are arranged.
A first phase plate between the liquid crystal cell and the second polarizing plate on the emission light side;
Since the slow axes of the two phase plates or the fast axes orthogonal thereto were almost aligned with the directions of the polarizing axes of the adjacent first and second polarizing plates, the observation was performed from the normal direction of the liquid crystal cell. The contrast is high, the steepness of the change in transmittance when a voltage is applied is good, and Δn of the light transmitted in the normal direction and the light transmitted in the oblique direction of the liquid crystal cell is Δn.
The difference in d is compensated to prevent a decrease in contrast when obliquely observed, thereby improving the viewing angle characteristics. In this case, the value of Δnd of the liquid crystal cell is 350 nm to 400 nm.
In this case, the value of Δnd of the phase plate is desirably in the range of a value obtained by multiplying the value of Δnd of the liquid crystal cell by 0.85 to 0.95.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, an upper substrate 1 and a lower substrate 2 made of transparent glass or the like are opposed to each other with a predetermined interval. A transparent common electrode 3 is formed on a lower surface of the upper substrate 1, and a first alignment film 4 is formed on a surface of the common electrode 3 and a display region of the upper substrate 1. A plurality of transparent pixel electrodes 5 are arranged in a matrix on the upper surface of the lower substrate 2, and each of the pixel electrodes 5 has a thin film transistor (TF) formed on the lower substrate 2.
T) 6 is connected. The TFT 6 has a source electrode connected to the pixel electrode 5, a gate electrode connected to a gate line formed on the lower substrate 2, and a drain electrode connected to a data line formed on the lower substrate 2. . These pixel electrodes 5, TFTs 6, gate lines and data lines are covered with a second alignment film 7, and the second alignment film 7 is formed at least in the display area of the lower substrate 2.

The second alignment film 7 of the lower substrate 2 and the first alignment film 7 of the upper substrate 1
As shown in FIG. 2, each of the alignment films 4 is subjected to an alignment process in a predetermined direction. The second alignment film 7 has been subjected to a rubbing process in a first alignment processing direction _Ao in the right front direction of the lower substrate 2, and the first alignment film 4 has a second alignment processing direction in the upper right direction of the upper substrate 1. The rubbing process is performed toward B. The first orientation direction _Ao and the second orientation direction B intersect at an angle of about 90 °.

The upper substrate 1 on which the common electrode 3 is formed and the lower substrate 2 on which the pixel electrode 5 is formed are joined to each other by a sealing material 8 at a predetermined interval. A region surrounded by the upper substrate 1, the lower substrate 2, and the sealant 8 is filled with a liquid crystal material 9. Thus, a liquid crystal layer is formed between the first alignment film 4 and the second alignment film 7, and a liquid crystal cell 10 is formed by the liquid crystal layer sandwiched between the lower substrate 2 and the upper substrate 1. I have.

The liquid crystal material 9 has a dielectric constant ratio Δε / ε |
2.44, a liquid crystal having physical properties in which the value of elastic constant ratio K ₃ / K ₁ is 1.43 and the value of K ₃ / K ₂ is 2.50, and the product of its refractive index anisotropy Δn and layer thickness d The value of Δnd (retardation) is set in the range of 450 nm to 550 nm. The liquid crystal molecules of the liquid crystal material 9 have a difference in the first alignment processing direction A _{o of} the first alignment film 4 and the second alignment processing direction B of the second alignment film 7 of approximately 90 °, so that They are arranged by being twisted approximately 90 ° counterclockwise from the first alignment processing direction _Ao toward the second alignment processing direction B of the upper substrate 1.
In this case, the value of d / p is set to about 0.05, and the pretilt angle of the liquid crystal molecules is about 1 °.

A polarizer (first polarizer) 11 composed of a linear polarizer is provided outside the lower substrate 2 of the liquid crystal cell 10 (incident light side).
Is provided outside the upper substrate 1 of the liquid crystal cell 10 (outgoing light side). An analyzer (second polarizing plate) 12 composed of a linear polarizing plate
Is provided. A first phase plate 13 is disposed between the liquid crystal cell 10 and the polarizer 11, and the liquid crystal cell 10 and the analyzer 12
The second phase plate 14 is disposed between the two. Polarizer 1
1, the polarization axis, for example, the transmission axis P ₁ is disposed substantially parallel to the first alignment treatment direction A _o. Analyzer 12 has its polarization axis, for example, the transmission axis P ₂ is arranged perpendicular to the transmission axis P ₁ of the polarizer 11. The first phase plate 13 is its slow axis R ₁ are disposed to be parallel or perpendicular to the first alignment treatment direction A _o. The second phase plate 14 has its slow axis R
₂ are disposed so as to be parallel or orthogonal to the first alignment processing direction _Ao . These phase plates 13 and 14 are formed to have the same phase difference, and the value of the phase difference Δnd is 3
It is set in the range of 00 nm to 400 nm. The phase plates 13 and 14 are made of the same material, for example, polycarbonate (PC) or polyvinyl alcohol (PVA), and are sandwiched between protective films such as triacetyl cellulose.

As in this liquid crystal display device, the liquid crystal cell 10
Is sandwiched between the first and second phase plates 13 and 14 and the first and second phase plates 13 and 14 are arranged so as not to be adjacent to each other. The axes R ₁ and R ₂ are arranged parallel or perpendicular to each other, and the slow axis R ₁ of the first phase plate 13 is set to the first alignment processing direction A _o of the liquid crystal cell 10.
When arranged so as to be parallel or orthogonal to
The contrast observed from the normal direction of 0 is high, and the steepness of the change in transmittance when a voltage is applied is good. In addition, the difference in Δnd of the liquid crystal cell 10 between the light transmitted in the normal direction of the liquid crystal cell 10 and the light transmitted in the oblique direction is compensated to prevent a decrease in contrast when observing from an oblique direction. improves.

By the way, in the liquid crystal display device having the above configuration, the value of Δnd of the liquid crystal layer is set to 510 nm (589).
nm), Δn of the phase plates 13 and 14
The value of d is 350 nm (a value measured with light having a wavelength of 589 nm), and the slow axis R _{1 of} the first phase plate 13 is
While disposed parallel or perpendicular to the first alignment treatment direction A _o 0, the slow axis R of the second phase plate 14
₂ was measured contrast was observed from each direction when a total of four types were disposed parallel or perpendicular to the first alignment treatment direction A _o of the liquid crystal cell 10. The result is shown in FIG.
(A) to FIG. 3 (D) show isocontrast curves. 3A to 3D, five concentric circles are sequentially arranged from the inner side to the outer side by 10 °, 20 ° with respect to the normal line of the liquid crystal display device, as in the case of the conventional example shown in FIG.
°, 30 °, 40 °, it represents the direction inclined at an angle of 50 °, also a first alignment treatment direction A _o of the liquid crystal cell 10 as a reference (0 °), as viewed from the incident light side of the liquid crystal cell 10 right The contrast observed in each direction is shown with the rotation (clockwise in the figure) as positive. The dotted line indicates a contrast of 100
, The one-dot chain line indicates the contrast 50, the solid line indicates the contrast 10, and the two-dot chain line indicates that the contrast is less than 1, that is, the display brightness is reversed. In measuring the contrast, a C light source was used, the value of the contrast was defined by the ratio of the Y value of the transmitted light, and the front contrast was about 100.

FIG. 3A shows the first alignment direction A
_FIG . 7 shows an isocontrast curve when the slow axes R ₁ and R ₂ of the first and second phase plates 13 and 14 are arranged in parallel to _o . In this case, as compared with the conventional example shown in FIG. 12, an inversion region where light and dark are inverted does not appear, and a region surrounded by a solid line and having a contrast of 10 or more is almost the same, and the viewing angle characteristics are improved. I have. FIG. 3B shows the first
Slow axis R ₁ of the first phase plate 13 with respect to the alignment treatment direction A _o
Are plotted in parallel, and the isocontrast curves when the slow axis R2 of the _second phase plate 14 is arranged perpendicular to the second phase plate 14 are shown. In this case, compared to the conventional example shown in FIG.
The inversion region does not appear, and the region surrounded by the solid line and having a contrast of 10 or more is widened in the left-right direction of the liquid crystal cell 10, and the viewing angle characteristics are improved. FIG. 3C shows the first and second phase plates 1 with respect to the first alignment direction _Ao .
3 shows isocontrast curves when the slow axes R ₁ and R ₂ of Nos. 3 and 14 are arranged orthogonal to each other. In this case, FIG.
The (A) isocontrast curve appears almost mirror-symmetric with respect to the vertical line of the liquid crystal cell 10. Therefore, as in the case shown in FIG. 3A, the inversion region does not appear, and the region surrounded by the solid line and having a contrast of 10 or more is almost the same, and the viewing angle characteristics are improved. FIG. 3 (D)
, When together arranged by orthogonal slow axis R ₁ of the first phase plate 13 relative to the first alignment treatment direction A _o, and the slow axis R ₂ of the second phase plate 14 is disposed in parallel 3 shows an iso-contrast curve. In this case, as compared with the conventional example shown in FIG. 12, the region surrounded by the solid line and having a contrast of 10 or more is slightly narrower as a whole, and the region below the liquid crystal cell 10
Although the inversion region surrounded by the dashed-dotted line appears small, the inversion region is narrow, so that the viewing angle characteristics are improved.

[0016] As described above, as well as arranged in parallel or perpendicular to the slow axis R ₁ of the first phase plate 13 relative to the first alignment treatment direction A _o, the slow axis R of the second phase plate 14 When placed in parallel or perpendicular ₂ to the first alignment treatment direction a _o, or the inversion region appearing in the vertical direction of the liquid crystal display device can be made extremely small, or that the inversion region is prevented appear at all And the viewing angle characteristics are improved.

The first and second phase plates 13,
4 to 7 show the results of measuring the electro-optical characteristics and the degree of coloring of the transmitted light in the on and off states for each of the cases in which 14 was arranged as described above. FIG.
4A and FIG. 4B are a CIE chromaticity diagram of the transmittance and the transmittance of the liquid crystal display device corresponding to FIG. 3A with respect to an applied voltage, and FIGS. 5A and 5B, respectively. ) Shows the relationship between the transmittance and the applied voltage in the liquid crystal display device corresponding to FIG. 3 (B) and the CIE chromaticity diagram of the transmitted light, and FIGS. 6 (A) and 6 (B) respectively show FIG. 3 (C). 7 (A) and FIG. 7 (B) show the relationship between the transmittance and the applied voltage in the liquid crystal display device corresponding to FIG.
FIG. 7 is a CIE chromaticity diagram of a relationship between transmittance and applied voltage in a liquid crystal display device corresponding to FIG. 13 and 14 show the relationship between the transmittance and the applied voltage in the conventional liquid crystal display device shown in FIG. 12 and the CIE chromaticity diagram of the transmitted light, respectively.

As is apparent from these figures, in the case of the liquid crystal display device of the embodiment using the phase plate, the transmittance in the ON state when the liquid crystal cell 10 is driven is high, and the change in the transmittance with respect to the applied voltage is high. Is steep. Moreover, as shown in the CIE chromaticity diagram, the color is substantially at an achromatic point in the ON state, and the degree of coloring is extremely small even in the OFF state. Therefore, according to this embodiment, it is possible to obtain a black-and-white display excellent in the steepness of the change in transmittance with respect to the application of a voltage and without coloring.

Next, in the liquid crystal display device having the structure shown in FIG. 2, the value of Δnd of the liquid crystal layer is set to 360 nm (589 nm).
Of the phase plates 13 and 14 are 300 nm, 350 nm and 400 nm (589).
and the slow axes R ₁ and R _{2 of} the first and second phase plates 13 and 14 are arranged so as to be parallel or orthogonal to the first alignment processing direction _Ao . 8 to 10 show the measurement results of the contrast observed from each direction in the case of the above.

FIG. 8A shows that the values of Δnd of the phase plates 13 and 14 are 300 nm, and that the phase plates 13 and 14 have the first orientation direction _Ao .
FIG. 8B is a diagram showing an equal contrast curve when the slow axes R ₁ and R ₂ of the second phase plates 13 and 14 are arranged so as to be parallel to each other. FIG. 30
In 0 nm, the first alignment treatment direction A _o, while arranged to be parallel to the slow axis R ₁ of the first phase plate 13, perpendicular to the slow axis R ₁ of the second phase plate 13 isocontrast curves when arranged manner, the value of Δnd shown in FIG. 8 (C) is a phase plate 13, 14 is 300 nm, the first alignment treatment direction a _o, late phase of the first phase plate 13 FIG. 11 is an isocontrast curve diagram when the axis R ₁ is arranged to be orthogonal and the slow axis R ₂ of the second phase plate 14 is arranged to be parallel.

FIG. 9 (A) in 350nm value of Δnd of the phase plates 13 and 14, the first alignment treatment direction A _o, the slow axis R of the first and second phase plates 13 and 14 _1, iso-contrast curves in the case of disposed parallel to R ₂ together view, and FIG. 9 (B) the value of Δnd of the phase plate 13, 14 35
In 0 nm, the first alignment treatment direction A _o, while arranged to be parallel to the slow axis R ₁ of the first phase plate 13, perpendicular to the slow axis R ₂ of the second phase plate 14 isocontrast curves when arranged manner, the value of Δnd shown in FIG. 9 (C) is a phase plate 13, 14 is 350 nm, the first alignment treatment direction a _o, late phase of the first phase plate 13 FIG. 11 is an isocontrast curve diagram when the axis R ₁ is arranged to be orthogonal and the slow axis R ₂ of the second phase plate 14 is arranged to be parallel.

FIG. 10A shows the Δnd of the phase plates 13 and 14.
Is 400 nm, and with respect to the first orientation direction _Ao ,
Each of the slow axes R ₁ , R _{2 of} the first and second phase plates 13, 14
Are equicontrast curves when both are arranged in parallel with each other. FIG. 10B shows that the values of Δnd of the phase plates 13 and 14 are 400 nm, and the first phase plate is in the first alignment processing direction _Ao . 13 as well as arranged to be parallel to the slow axis R ₁ of iso-contrast curves in the case of arranging so as to be orthogonal to the slow axis R ₂ of the second phase plate 14, FIG. 10 (C) is a phase plate the value of Δnd of 13 and 14 at 400 nm, the first alignment treatment direction a _o, the slow axis R ₁ of the first phase plate 13
Are arranged so as to be orthogonal, and the second phase plate 14
If you place the slow axis R ₂ to be parallel isocontrast curves of.

The value of Δnd of the phase plates 13 and 14 is 3
Nm, 350 nm, be either 400nm of the first alignment treatment direction A _o, the slow axis R ₁ of the first and second phase plate 13, 14, R ₂ together to be perpendicular 8 (A), FIG. 9 (A), FIG.
Since each contrast curve of 0 (A) appears almost mirror-symmetric with respect to the vertical line on the drawing, it is not shown. The physical properties of the liquid crystal in this case are as follows: the value of the dielectric constant ratio Δε / ε | is 1.25, and the value of the elastic constant ratio K ₃ / K ₁ is
The values of 1.57 and K ₃ / K ₂ are 2.30. 8 to 10, the three-dot chain line indicates the contrast 150.

As is apparent from these figures, in any case, the inversion area appearing in the vertical direction of the liquid crystal display device can be made extremely small as compared with the conventional example shown in FIG. Can be prevented from appearing at all, and the viewing angle characteristics are improved. 8A, FIG. 9A, FIG. 9C, FIG. 10A, and FIG. 10C, an area with a contrast of 50 or more surrounded by a dashed line is shown. 8 (B), 9 (B) and 10 (B), a region surrounded by a dashed line and having a contrast of 50 or more extends in the horizontal direction of the liquid crystal display device. This also improves the viewing angle characteristics. Focusing on the value of Δnd of the phase plates 13 and 14, the larger the value of Δnd of the phase plates, the wider the area with high contrast. Therefore, the value of Δnd of the phase plates 13 and 14 is preferably large, and the value is preferably in the range of 300 nm to 600 nm. The value of Δnd of the liquid crystal cell 10 is 350 n
It is preferably in the range of m to 700 nm, and the smaller the value, the better the viewing angle characteristics. Therefore, the value of Δnd of the liquid crystal cell 10 is preferably equal to or less than 550 nm, and particularly preferably about 360 nm.

Further, in the arrangement of the phase plates 13 and 14 described with reference to FIG.
When the value of Δnd of the phase plates 13 and 14 is set to 300 nm to 380 nm and the phase plate 13 and 14 is set to 300 nm to 380 nm, the vertical viewing angle of the liquid crystal display device increases as shown in FIG.
Therefore, the phase plates 13 and 14 described with reference to FIG.
In the above arrangement, it is desirable that the value of Δnd of the phase plates 13 and 14 be in the range of a value obtained by multiplying the value of Δnd of the liquid crystal layer by 0.85 to 0.95.

[0026]

As described above, according to the present invention, the first phase plate is arranged between the liquid crystal cell and the first polarizing plate on the incident light side, and the second polarizing plate on the liquid crystal cell and the outgoing light side. A second phase plate is disposed between the first and second polarizers, and the slow axis of these two phase plates or the fast axis orthogonal to the second phase plate is set to the direction of the polarization axes of the adjacent first and second polarizers. Since they almost match, the contrast observed from the normal direction of the liquid crystal cell is high, and the steepness of the change in transmittance when voltage is applied is improved, and the light transmitted in the normal direction of the liquid crystal cell is oblique. It is possible to compensate for the difference in Δnd of the light transmitted through the liquid crystal cell in the liquid crystal cell, to prevent a decrease in contrast when obliquely observed, and to improve the viewing angle characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating the liquid crystal display device of FIG.

3 (A) to 3 (D) are isocontrast curves showing respective viewing angle characteristics in a case where a setting angle of a slow axis of a phase plate is different.

FIGS. 4A and 4B are voltage-luminance characteristics and a CIE chromaticity diagram of transmitted light of the liquid crystal display device having the phase plate installation angle of FIG. 3A.

5A and 5B are voltage-luminance characteristics and a CIE chromaticity diagram of transmitted light of the liquid crystal display device having the phase plate installation angle of FIG. 3B.

6A and 6B are voltage-luminance characteristics and a CIE chromaticity diagram of transmitted light of the liquid crystal display device having the phase plate installation angle of FIG. 3C.

7A and 7B are voltage-luminance characteristics and a CIE chromaticity diagram of transmitted light of the liquid crystal display device having the phase plate installation angle of FIG. 3D.

8 (A) to 8 (C) show liquid crystal display devices according to this embodiment in which a phase plate having a value of Δnd of 300 nm is used and the phase plate has a different setting angle of a slow axis. FIG. 3 is an isocontrast curve diagram showing viewing angle characteristics.

9 (A) to 9 (C) show the liquid crystal display device of this embodiment when a phase plate having a value of Δnd of 350 nm is used and the phase plate has a different setting angle of a slow axis. FIG. 3 is an isocontrast curve diagram showing viewing angle characteristics.

10 (A) to 10 (C) show the liquid crystal display device of this embodiment when a phase plate having a value of Δnd of 400 nm is used and when the installation angle of the slow axis of the phase plate is different. FIG. 3 is an isocontrast curve diagram showing viewing angle characteristics.

FIG. 11 is an isocontrast curve diagram showing viewing angle characteristics when the value of Δnd of the phase plate is a value obtained by multiplying the value of Δnd of the liquid crystal layer by 0.85 to 0.95 in the liquid crystal display device of this embodiment.

FIG. 12 is an equal contrast diagram showing viewing angle characteristics in a conventional liquid crystal display device.

FIG. 13 is a voltage-luminance characteristic diagram of the liquid crystal display device of FIG.

FIG. 14 is a CIE chromaticity diagram showing a change in display color of the liquid crystal display device of FIG.

[Explanation of symbols]

 Reference Signs List 9 liquid crystal material 10 liquid crystal cell 11 polarizer 12 analyzer 13 first phase plate 14 second phase plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-132720 (JP, A) JP-A-55-62430 (JP, A) JP-A-62-210423 (JP, A) JP-A-1- 230019 (JP, A) JP-A-1-254917 (JP, A) JP-A-2-7018 (JP, A) JP-A-2-47625 (JP, A) JP-A-2-66517 (JP, A) JP-A-2-125224 (JP, A) JP-A-4-32818 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/13363

Claims (3)

(57) [Claims] 1. A liquid crystal of a liquid crystal material filled between a pair of substrates.
Forming a liquid crystal layer molecules are oriented approximately 90 ° twist
And a twisted nematic liquid crystal cell sandwiched between the pair of substrates , and disposed on the incident light side of the liquid crystal cell, and its polarization axis is orthogonal to the alignment processing direction on the incident light side of the liquid crystal cell. A first polarizing plate oriented in a parallel direction, a first phase plate disposed between the first polarizing plate and the liquid crystal cell, and a first polarization plate disposed on an emission light side of the liquid crystal cell and having a polarization axis thereof. A second polarizing plate substantially orthogonal to a polarization axis of the first polarizing plate; and a second phase plate disposed between the second polarizing plate and the liquid crystal cell. The second phase plate is arranged such that the slow axis or the fast axis orthogonal thereto is arranged in a direction substantially coincident with the directions of the respective polarization axes of the adjacent first and second polarizing plates. Characteristic liquid crystal display device. 2. The Δnd of the first phase plate and the second phase plate
Is 0.85 to the value of Δnd of the liquid crystal cell, respectively.
2. The liquid crystal display device according to claim 1, wherein the value is in the range of a value obtained by multiplying by 0.95. Wherein the value of Δnd of the liquid crystal cell is substantially 350
The liquid crystal display device according to claim 1 , wherein the thickness is in the range of 400 nm to 400 nm.