JPH08160383A - Color liquid crystal display - Google Patents

Abstract

(57) [Abstract] [Object] A color liquid crystal display device is capable of obtaining a high-purity color display, white display, and black display by utilizing light interference due to birefringence of liquid crystal without using a color filter. Provided is a liquid crystal display device. [Structure] A liquid crystal cell having an initial retardation value of 500 or more and using a P-type liquid crystal in which liquid crystal molecules 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ , 3 ₅ are twisted in the direction of an electric field is used as a lower polarizing plate 4 and an upper side. In a color liquid crystal display device which is sandwiched between polarizing plates 5 and develops color by utilizing interference of transmitted light or reflected light due to birefringence of liquid crystal, a uniaxial retardation value of 50 to 200 nm is provided between the upper substrate 2 and the upper polarizing plate 5. Liquid crystal molecule 3 which is inserted between the lower retardation plate 1 ₁ and the upper orientation plate 2 ₁ of the liquid crystal cell in a state where a high voltage is applied by the uniaxial retardation film 6 and which does not stand up. ₁ , 3
Improve the color purity and white brightness by compensating the residual retardation caused by ₅ .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a color liquid crystal display device utilizing interference of transmitted light or reflected light due to birefringence of liquid crystal. In recent years, expectations for light-weight, thin, and low-power liquid crystal display devices have been increasing, and various types of liquid crystal display devices have been proposed in order to meet those expectations, and to realize those liquid crystal display devices. The technological development of is also diversified.

Among them, color display is possible as a liquid crystal display device to be mounted on a portable notebook type or notebook type personal computer, an OA terminal device, a word processor, etc. for which low power consumption and cost reduction are particularly desired. Since a backlight is unnecessary, it is desired to develop a reflective color liquid crystal display device with low power consumption and low cost.

The color developing methods of liquid crystal display devices are roughly classified into
It is divided into a method using a color filter and a method using an interference color due to a birefringence effect that changes due to the tilt angle of liquid crystal molecules. However, in a liquid crystal display device using a color filter, the amount of light transmission is significantly increased by the color filter. And it is necessary to divide one pixel into RGB into three,
The manufacturing process is complicated, which is disadvantageous in terms of brightness and resolution.

The present invention relates to a transmissive or reflective color liquid crystal display device, and in particular, color development utilizing the birefringence effect of liquid crystal, that is, SBE (Super-twisted).
Birefringence Effect), ECB
(Electrically Controlled B
It is an object of the present invention to improve a color display device based on irringence and the like.

[0005]

2. Description of the Related Art In the color liquid crystal display device utilizing the ECB type birefringence effect, the voltage applied to the liquid crystal cell is changed to control the tilt angle of the liquid crystal molecules, and the tilt angle of the liquid crystal molecules is changed. It is possible to change the birefringence state of light passing through the liquid crystal cell and change the display color by mutual interference of the birefringent lights. Generally, since the ECB type liquid crystal display device has a poor viewing angle characteristic, many of them have been designed to improve the viewing angle characteristic by setting the twist angle of the liquid crystal molecules to 180 degrees or more.

6A and 6B are explanatory views of the relationship between applied voltage, color development and brightness of a conventional liquid crystal display device, FIG. 6A is a relationship diagram of applied voltage, brightness and color development, and FIG. 6B is a chromaticity diagram. According to these figures, the initial retardation value, which is the product Δn · d of the refractive index anisotropy Δn and the thickness d of the liquid crystal layer when an extremely low voltage is applied (referred to as no voltage applied state), is 1400.
In a P-type liquid crystal display device of nm, the brightness changes as the applied voltage is increased, and the colors are green, red, blue, black,
It has changed to ashes. Then, ash with a luminance of 50% is obtained when the applied voltage is within 6 V which is used as a TFT driving voltage of a normal liquid crystal display device.

Note that 100% in this figure is the ratio of the reflected light to the incident light of a system in which two polarizing plates are placed in parallel and a reflecting plate is placed below the polarizing plate. Is the upper limit. In this case, the retardation value decreases with increasing voltage, so unless the liquid crystal with a large initial retardation value in the no voltage applied state is selected, the number of colors is limited, so that the basic red, blue,
To obtain green, about 1200 nm, preferably 1450
An initial retardation value of about nm is necessary. However, in the case of performing identification by the minimum number of colors such as a personal computer or a word processor, an initial retardation value of about 500 nm at which blue is developed can achieve the intended purpose.

Further, in the ECB type liquid crystal display device, as described above, since the color is developed by the applied voltage,
When applied to passive driving of a simple matrix type, the voltage applied to a specific pixel is attenuated with time, the color changes, and high color purity cannot be obtained. It is desirable to apply to a TFT drive type capable of reducing the attenuation of the voltage applied to the pixel.

[0009]

As is apparent from the above description, considering the case of para-Nicol in which the polarization axes of the polarizing plates sandwiching the liquid crystal cell are parallel, all the liquid crystal molecules uniformly respond to the applied voltage. If a state that rises by an angle can be realized, high-purity color development should be obtained, and white display should be obtained when all liquid crystal molecules are completely raised. However, in an actual liquid crystal display device, the liquid crystal molecules in contact with the alignment film do not rise to the same angle as the tilt angle of the liquid crystal molecules at a position apart from the alignment film due to the strong alignment film anchoring, and the so-called Due to residual retardation of the liquid crystal, good color purity and perfect white display could not be obtained. On the contrary, in the case of crossed Nicols in which the polarization axes of the alignment plates that sandwich the liquid crystal cell intersect, perfect black display cannot be obtained.

7A and 7B are schematic structural explanatory views of a conventional liquid crystal display device. FIG. 7A is a perspective view and FIG. 7B is a plan view. In this figure, 41 is a lower substrate, 41 ₁ is a lower alignment film,
42 is an upper substrate, 42 ₁ is an upper alignment film, 43 ₁ , 4
3 ₂ , 43 ₃ , 43 ₄ , and 43 ₅ are liquid crystal molecules, 44 is a lower polarizing plate, 44 ₁ and 45 ₁ are polarizing axes, and 45 is an upper polarizing plate.

Transmission light or reflection due to this conventional birefringence
The ECB type liquid crystal display device utilizing the interference of light has a lower alignment.
Membrane 41₁Lower substrate 41 having a transparent electrode and an upper alignment film
42 ₁Liquid crystal in the gap between the upper substrate 42 having a transparent electrode and
Numerator 43₁, 43₂, 43₃, 43_Four, 43_FiveAs a table
Filled with the P-type liquid crystal that has been exposed, and the lower polarizing plate on the outside of it.
44 and the upper polarizing plate 45 with their polarization axes 44₁And polarization
Axis 45₁(Paranicol) structure with the parallel to each other
have.

A voltage is applied between the transparent electrodes of this liquid crystal display device.
When added, the lower alignment film 41₁And the upper alignment film 42₁Between
Liquid crystal molecule 43₂, 43₃, 43_FourResponds to the applied voltage
Rises, but the lower alignment film 41₁And the upper alignment film 42₁
Liquid crystal molecules 43 in contact with ₁And 43_FiveIs a strong alignment film
It remains without standing up due to the muffler ring.

As a result, residual retardation (because two liquid crystal molecules 43 ₁ and 43 ₅ remain on the two alignment films) 2R
As a result, a perfect white display cannot be obtained even if the applied voltage is increased, and a high-purity color display cannot be performed for other colors. Lower polarizing plate 4
On the contrary, in the case of crossed Nicols in which the polarization axis 44 _{1 of No.} 4 and the polarization axis 45 ₁ of the upper polarization plate 45 intersect, on the contrary, it is impossible to obtain a color display with high purity and a perfect black display.

This explanation is for compensation of residual retardation.
As far as it is concerned, liquid crystal molecules 43₂, 43 ₃, 43_FourIs a twist
Even in homogeneous color liquid crystal display devices that do not
Even in color liquid crystal display devices where liquid crystal molecules are twisted
The same applies.

That is, in both the case of para-Nicol and the case of cross-Nicol, it was not possible to obtain a highly pure color display and complete white display and black display. Of course, by applying an extremely high voltage, it is theoretically possible to overcome the alignment film anchoring and raise the liquid crystal molecules to obtain a complete white display or black display. It is disadvantageous because
With such a high voltage, it becomes impossible to drive the liquid crystal using a TFT having a low breakdown voltage.

Further, as shown in FIG. 6 described above, only gray display is obtained within the range of applied voltage which is normally limited to 6 V or less for driving the TFT, and the brightness thereof is 50. Only about%. On the other hand, in an N-type liquid crystal display device, a method may be considered in which ECB is applied to liquid crystal molecules that are vertically aligned without applying a voltage to achieve both black and white, but the visual characteristics when a voltage is applied are extremely poor. It cannot be put to practical use.

The present invention provides a color liquid crystal display device which can obtain a high-purity color display, white display and black display by utilizing light interference due to birefringence of liquid crystal without using a color filter. The purpose is to

[0018]

A P-type liquid crystal according to the present invention is used which twists liquid crystal molecules in the direction of an electric field with an initial retardation value of 500 nm or more when a low voltage is applied (no voltage applied). In a color liquid crystal display device having a structure in which a liquid crystal cell is sandwiched between two polarizing plates and utilizing light interference due to birefringence of liquid crystal, a retardation value is provided between the liquid crystal cell and at least one polarizing plate. Fifty
A uniaxial retardation film having a thickness of up to 200 nm was inserted, and the residual retardation generated by the liquid crystal molecules in contact with the alignment film of the liquid crystal cell was canceled by the uniaxial retardation film.

In this case, the liquid crystal layer can be twisted by 180 to 360 degrees to improve the viewing angle characteristics, and the two polarizing plates sandwiching the liquid crystal cell are para-Nicol or cross-Nicol, and the average of the polarization axes of each polarizing plate is The birefringence characteristic of the liquid crystal molecules can be improved by making the optical axis form an angle of 45 degrees with the long axis direction of the liquid crystal molecules at the center in the depth direction of the liquid crystal layer.

Further, the liquid crystal layer is driven by the TFT,
The color purity can be improved by suppressing the fluctuation of the voltage applied to each pixel of the liquid crystal cell. In addition, a reflection plate is provided outside one of the polarizing plates to serve as a reflection type liquid crystal display device to save power for lighting a backlight and to transmit incident light twice in a liquid crystal layer to thereby generate a color. The effect can be enhanced.

[0021]

1A and 1B are schematic structural explanatory views of a color liquid crystal display device of the present invention. FIG. 1A is a perspective view and FIG. 1B is a plan view. In this figure, 1 is the lower substrate, ₁₁ is the lower alignment film,
2 is an upper substrate, 2 ₁ is an upper alignment film, 3 ₁ , 3 ₂ , 3 ₃ ,
3 ₄ and 3 ₅ are liquid crystal molecules, 4 is a lower polarizing plate, 4 ₁ and 5 ₁ are polarization axes, 5 is an upper polarizing plate, and 6 is a uniaxial retardation film.

The transmitted light or the reflected light due to the birefringence of the present invention
The ECB type liquid crystal display device that utilizes the interference of the emitted light is
Membrane 1₁A lower substrate 1 having a transparent electrode and an upper alignment film
2₁And the upper substrate 2 having a transparent electrode are arranged to face each other,
Liquid crystal molecules 3 in the gap₁, 3 ₂, 3₃, 3_Four, 3_Fiveage
The P-type liquid crystal shown in Fig.
The light plate 4 and the upper polarizing plate 5 are arranged with their polarization axes 4₁And the polarization axis
5₁Are arranged in parallel (paranicols), and
Optical anisotropy between the upper polarizing plates 5 due to uniaxial stretching or the like.
A uniaxial retardation film 6 made of a polymer material etc.
It has a structure in which is inserted.

When a voltage is applied between the transparent electrodes of this liquid crystal display device, the liquid crystal molecules 3 ₂ , 3 ₃ , 3 ₄ between the lower alignment film 1 ₁ and the upper alignment film 2 ₁ respond to the applied voltage. Although rising, the liquid crystal molecules 3 ₁ and 3 ₅ in contact with the lower alignment film 1 ₁ and the upper alignment film 2 ₁ remain without rising due to strong alignment film anchoring.

In this liquid crystal display device, when the uniaxial retardation film 6 is not interposed between the upper substrate 2 and the upper polarizing plate 5, as described in the prior art, the lower alignment film 1 is used. _{Since the} liquid crystal molecules 3 ₁ , 3 ₅ that remain in contact with ₁ and the upper alignment film 2 ₁ and do not stand up cause residual retardation 2R, color display with high color purity and perfect white display and black display cannot be obtained. .

In the present invention, as described above, the liquid crystal molecules 3 remaining between the upper substrate 2 and the upper polarizing plate 5 in contact with the lower alignment film 1 ₁ and the upper alignment film 2 ₁ and not standing up. Uniaxial retardation film 6 having a retardation value similar to that of residual retardation 2R due to ₁ , 3 ₅
And by its slow phase axis are perpendicular with residual retardation 2R interposing, it is possible to obtain a liquid crystal molecule 3 _1, 3 ₅ due to the residual retardation 2R pure color display and white display by canceling the.

As far as the compensation of the residual retardation is concerned, this explanation is similarly applied to the homogeneous color liquid crystal display device in which the liquid crystal molecules 3 ₂ , 3 ₃ and 3 ₄ are not twisted and the twisted color liquid crystal display device.

The liquid crystal display device itself is an optical shutter that is essentially free of color, and attention has heretofore been focused on reducing the residual retardation of liquid crystal molecules that causes color in the STN liquid crystal display device. Since a liquid crystal having an initial retardation in the absence of applied voltage of less than about 600 nm was used, it was not always difficult to compensate for this initial retardation with a uniaxial retardation film having a retardation of about 600 nm. .

However, according to the present invention, in order to obtain a color display by tilting the liquid crystal molecules, the minimum residual retardation when a low voltage is applied as described above is set to 500 nm, which is a blue display. , A blue liquid crystal, a green liquid, and a red liquid crystal are obtained at about 1200 nm, and a high-brightness liquid crystal up to about 2000 nm is used. Therefore, it is necessary to use a thick uniaxial retardation film, and if such a thick uniaxial retardation film is used, the response characteristics deteriorate and the viewing angle characteristics of the liquid crystal display device deteriorate significantly.

The inventors of the present invention, as shown in FIG. 3, have an initial retardation of 1500 when no voltage is applied.
Even if the liquid crystal is as large as ˜2000 nm, the residual retardation is reduced to about 100 nm when a high voltage is applied within a practical range for a liquid crystal display device. By compensating for this with a uniaxial retardation film that is thin enough not to degrade the responsiveness and viewing angle characteristics, we changed the concept of alleviating the deterioration of color display due to residual retardation.

Although the present invention cannot sufficiently compensate for the initial retardation in the state where no voltage is applied, in the originally dark reflection type liquid crystal display device, as in the present invention,
By compensating for the residual retardation under high voltage application, the purity of the color that develops when a relatively high voltage is applied is improved, and the brightness of white display, which is important for display characteristics, is significantly improved. You can

FIG. 2 is an explanatory view of the principle of the color liquid crystal display device of the present invention, in which (A) is a cross-sectional view in the state where no voltage is applied,
(B) is a top view when a homogeneous liquid crystal is used,
(C) is a top view when a 200 degree twist liquid crystal is used,
(D) is a cross-sectional view when voltage is applied, and (E) is a top view when voltage is applied.

In the figure, 11 is a liquid crystal cell, 11 ₁ is a residual retardation, 12 is a liquid crystal molecule, 13 is a lower alignment film, 1
3 ₁ and 14 ₁ are rubbing directions, 14 is an upper alignment film, and 15
Is a lower polarizing plate, 15 ₁ and 16 ₁ are polarizing axes, 16 is an upper polarizing plate, 17 is a uniaxial retardation film, 17 ₁ is a slow axis of the uniaxial phase film, and 18 is a power source.

In the color liquid crystal display device of the present invention,
A liquid crystal cell 11 in which a liquid crystal represented by liquid crystal molecules 12 is sandwiched between a lower alignment film 13 having a transparent electrode and an upper alignment film 14.
A lower polarizing plate 15 is disposed underneath, and a uniaxial retardation film (retardation film) 17 is disposed on the liquid crystal cell 11.
The upper polarizing plate 16 is disposed via the (see cross-sectional view (A) in the state where no voltage is applied).

In the case of performing para-Nicol polarization using homogeneous liquid crystal, the rubbing direction (broken line) 13 ₁ of the lower alignment film 13 of the liquid crystal cell 11 and the rubbing direction (solid line) 14 ₁ of the upper alignment film 14 are parallel to the same direction. And the lower polarizing plate 15
The polarization axis 14 ₁ of the polarization axis 15 ₁ and the upper polarizing plate 14 are parallel, the rubbing direction 14 _first rubbing direction 13 ₁ and the upper alignment layer 14 of the lower alignment layer 13, i.e., the liquid crystal layer depth direction of The major axis direction of the central liquid crystal molecule 12 is the lower polarizing plate 1.
4 on the polarization axis 15 _{1 of} 5 and the polarization axis 16 ₁ of the upper polarizing plate 16
Crosses at 5 degrees (top view of homogeneous liquid crystal (B))
reference).

In addition, a 200 ° twist liquid crystal is used to
When performing Nicol polarization, the lower alignment film 1 of the liquid crystal cell 11
Rubbing direction 3 (broken line) 13₁And the upper alignment film 14
Bing direction (solid line) 14₁Is a clockwise angle of 200 degrees
Crosses the polarization axis 15 of the lower polarizing plate 15.₁And the upper polarizer
16 polarization axes 16₁Are parallel, and the Rabin of the lower alignment film 13 is
Direction 13₁And the rubbing direction 14 of the upper alignment film 14₁of
The central liquid crystal part in the middle direction, that is, in the depth direction of the liquid crystal layer
The long axis direction of the child is the polarization axis 15 of the lower polarizing plate 15. ₁And above
Polarization axis 16 of polarizing plate 16₁Cross at 45 degrees (2
The top view (C) of a 00 degree twist liquid crystal).

With such an angular relationship, the incident light that has been polarized in the direction of its polarization axis 16 ₁ and passed through the upper polarizing plate 16 is the center of the liquid crystal layer in the depth direction, which is most affected by the applied voltage. Optimizing the coloring effect due to interference, since birefringence is performed by liquid crystal molecules in the vicinity with a substantially equal amount of light, and transmitted light or reflected light with an equal amount of light interferes and passes through the lower polarizing plate 15 or the upper polarizing plate 16. You can

A power source 18 is provided between the transparent electrodes of the liquid crystal cell 11.
When a voltage is applied by the liquid crystal cell 11, the liquid crystal molecules 12 in the middle layer of the liquid crystal cell 11 stand up by an angle corresponding to the voltage, but the liquid crystal molecules 12 in contact with the lower alignment film 13 and the upper alignment film 14 have strong polarizing plate anchoring. Therefore, it cannot be erected and remains (see cross-sectional view (D) when voltage is applied).

As a result, the residual retardation 2R is generated on the flat surface of the liquid crystal cell 11, and in this state as it is, the color purity in the color display deteriorates, and perfect white display and black display cannot be obtained. .

In the color liquid crystal display device of the present invention,
As described above, between the upper alignment film 14 and the upper polarization plate 16, the residual retardation (2R), which is almost the same as the residual retardation (2R) generated by the liquid crystal molecules that cannot be raised by the anchoring of the lower alignment film 13 and the upper alignment film 14. Slow axis 17 ₁ of uniaxial phase film having phase delay characteristic (-2R)
Since it is inserted so as to be orthogonal to the direction of residual retardation, the relationship of (2R) + (− 2R) ≈0 is satisfied, and residual retardation can be compensated (see top view (E) at the time of voltage application).

In order to drive the liquid crystal panel 11 by the TFT, it is necessary at present that the applied voltage be 6 V or less, but according to the present invention, when the voltage within 6 V is applied, the color purity of Good color display and white display can be obtained.

FIG. 3 is a diagram for explaining the relationship between the voltage applied by the liquid crystal and the residual retardation value. The horizontal axis of this figure shows the applied voltage, and the vertical axis shows the residual retardation value when the twist angle is 180 °, but the initial retardation value was about 1420 nm when no voltage was applied. When the applied voltage is 6 V, the liquid crystal [TL-
202] (manufactured by Merck) is slightly higher than 169 nm,
[RDP-31192E] (manufactured by Rodick), [FT-
5028LB] (manufactured by Chisso) 100 nm to 110 n
It shows a low value of m.

Considering the possibility of slightly increasing the applied voltage, the residual retardation value can be estimated to be about 50 to 200 nm. Therefore, the retardation value of the uniaxial retardation film that compensates for this is also 50 to 20.
It can be 0 nm.

The present invention can be applied to both a transmissive liquid crystal display device and a reflective liquid crystal display device. When applied to a reflective liquid crystal display device, incident light and reflected light have a birefringence effect of liquid crystal. Excellent color development due to repeated exposure.

[0044]

Embodiments of the present invention will be described below. FIG.
1A and 1B are explanatory views of a color liquid crystal display device according to an embodiment of the present invention, FIG. In this figure, 21 is the lower glass plate, 22 is the TFT array, and 23.
Is a lower alignment film, 24 is a liquid crystal cell, 24 ₁ is a liquid crystal molecule, 2
4 ₂ is residual retardation, 25 is upper alignment film, 26 is ITO transparent electrode, 27 is upper glass plate, 28 is uniaxial retardation film, 28 ₁ is slow axis of uniaxial phase film,
Reference numeral 29 is a lower polarizing plate, 30 is an upper polarizing plate, and 31 is a reflecting plate.

In the color liquid crystal display device of this embodiment, as shown in FIG. 4A, first, the TFT array 22 is formed on the lower glass plate 21, and the lower alignment film 23 is formed thereon. And then I on the upper glass plate 27.
The TO transparent electrode 26 is formed, and the upper alignment film 25 is formed thereon.

Then, the lower glass plate 21 and the upper glass plate 27 are made to face each other with the lower alignment film 23 and the upper alignment film 25 facing each other with a gap, and the initial retardation value is ~
A low voltage liquid crystal (liquid crystal molecule 24 ₁ ) (manufactured by Chisso) having a twist angle of 180 ° at 1500 nm is filled and the periphery is sealed to assemble the liquid crystal cell 24. Below the liquid crystal cell 24, a lower polarizing plate 29 and a reflecting plate 31 are provided, and the liquid crystal cell 2
4, a uniaxial retardation film 28 having a retardation value of 70 nm and an upper polarizing plate 30 are arranged to complete the process.
In this embodiment, twisting 180 to 360 degrees can improve the viewing angle characteristics.

This liquid crystal display device is shown in FIG.
Rubbing direction of the lower alignment film 23 (broken line) 2
Three₁And the rubbing direction (solid line) 25 of the upper alignment film 25₁But
It is parallel to the opposite direction and the polarization axis 29 of the lower polarizing plate 29.₁When
Polarization axis 30 of upper polarizing plate 30 ₁Are parallel, bottom orientation
Rubbing direction 23 of film 23₁And Rabin of the upper alignment film 25
Direction 25₁, That is, the central liquid crystal in the depth direction of the liquid crystal layer
Molecule 24₁The long axis direction of is the polarization axis 29 of the lower polarizing plate 29.
₁And the polarization axis 30 of the upper polarizing plate 30₁Cross at 45 degrees
There is. Slow axis 28 of uniaxial phase film₁Is the bottom orientation
The liquid crystal molecules in contact with the film 23 and the upper alignment film 25 generate
Residual retardation 24₂Is orthogonal to.

FIG. 5 is an explanatory diagram of the relationship between applied voltage, color development and brightness of the color liquid crystal display device of the present invention, (A) is a relationship diagram of applied voltage, brightness and color development, and (B) is a chromaticity diagram. is there. According to these figures, the retardation value, which is the product Δn · d of the refractive index anisotropy Δn and the thickness d of the liquid crystal layer, is 1400.
In the P-type liquid crystal display device of nm, it can be seen that as the applied voltage is increased, it changes with brightness such as green, red, blue, black and white. Further, as apparent from comparison with the characteristics of the conventional liquid crystal display device of FIG. 6, the applied voltage is 6V used as a TFT drive voltage of a normal liquid crystal display device.
Within that range, black, red, and green were obtained, and white close to 100% luminance was obtained.

In a normally white liquid crystal display device that compensates for initial retardation in the absence of applied voltage, in the case of para-nicol, white, black, and color change as the applied voltage increases (in the case of crossed nicols). Changes to black, white, and color), but black is close to the threshold value, and when the twist angle is set to be large to some extent, the threshold characteristic is steep, and black is too rapid to adjust the voltage. Will be lower.

According to the present invention, white is displayed when the highest voltage is applied, and black is immediately before that, and the color change due to the voltage is moderate, so that voltage adjustment is relatively easy and high contrast is achieved. The black and white display that is obtained and is the most important for display is excellent.

[0051]

As described above, according to the color liquid crystal display device of the present invention, it is possible to display a color including white and black within a voltage range capable of driving a TFT within 6 V without using a color filter. In addition, since the twist angle can be increased, the viewing angle characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view of a color liquid crystal display device of the present invention, (A) is a perspective view, and (B) is a plan view.

2A and 2B are explanatory views of the principle of the color liquid crystal display device of the present invention, in which FIG. 2A is a cross-sectional view of a state in which no voltage is applied, FIG. 2B is a top view when a homogeneous liquid crystal is used, and FIG. FIG. 6 is a top view when a twisted liquid crystal is used, (D) is a cross-sectional view when a voltage is applied, and (E) is a top view when a voltage is applied.

FIG. 3 is an explanatory diagram of a relationship between a voltage applied by a liquid crystal and a residual retardation value.

4A and 4B are explanatory views of a color liquid crystal display device according to an embodiment of the present invention, in which FIG. 4A is a sectional view and FIG. 4B is an explanatory plan view.

5A and 5B are explanatory diagrams of the relationship between applied voltage, color development and brightness of the color liquid crystal display device of the present invention, FIG. 5A is a relationship diagram of applied voltage, brightness and color development, and FIG. 5B is a chromaticity diagram.

6A and 6B are explanatory views showing the relationship between an applied voltage, color development and luminance of a conventional liquid crystal display device, FIG. 6A is a relationship diagram of applied voltage, luminance and color development, and FIG. 6B is a chromaticity diagram.

FIG. 7 is a schematic configuration explanatory view of a conventional liquid crystal display device,
(A) is a perspective view and (B) is a plan view.

[Explanation of symbols]

1 Lower Substrate 1 ₁ Lower Alignment Film 2 Upper Substrate 2 ₁ Upper Alignment Film 3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ , 3 ₅ Liquid Crystal Molecule 4 Lower Polarizer 4 ₁ , 5 ₁ Polarization Axis 5 Upper Polarizer 6 uniaxial retardation film 11 liquid crystal cell 11 ₁ residual retardation 12 liquid crystal molecules 13 lower alignment film 13 ₁ , 14 ₁ rubbing direction 14 upper alignment film 15 lower polarization plate 15 ₁ , 16 ₁ polarization axis 16 upper polarization plate 17 uniaxial Retardation film 17 ₁ Slow axis of uniaxial phase film 18 Power supply 21 Lower glass plate 22 TFT array 23 Lower alignment film 24 Liquid crystal cell 24 ₁ Liquid crystal molecule 24 ₂ Residual retardation 25 Upper alignment film 26 ITO transparent electrode 27 Upper side glass plate 28 uniaxial retardation film 28 ₁ uniaxial phase film in the slow axis 29 lower polarizing plate 30 upper polarizing plate 31 reflector plate 41 lower substrate 41 _first lower alignment layer 42 on Substrate 42 _first upper alignment layer 43 _1, 43 _2, 43 _3, 43 _4, 43 ₅ liquid crystal molecules 44 lower polarizing plate 44 _1, 45 ₁ polarization axis 45 the upper polarizer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimiaki Nakamura 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Hideaki Tsuda 1015, Kamedotachu, Nakahara-ku, Kawasaki, Kanagawa Prefecture Fujitsu Limited ( 72) Inventor Hideo Senda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (5)

[Claims] 1. A structure having a structure in which a liquid crystal cell using a P-type liquid crystal having an initial retardation value of 500 nm or more and twisting liquid crystal molecules in the direction of an electric field is sandwiched between two polarizing plates. In a color liquid crystal display device utilizing interference, between the liquid crystal cell and at least one polarizing plate,
A retardation value is 50 to 200 nm, and a residual retardation generated by liquid crystal molecules in contact with an alignment film of the liquid crystal cell is compensated by a slow axis of the uniaxial retardation film. Color liquid crystal display device. 2. The color liquid crystal display device according to claim 1, wherein the liquid crystal is twisted by 180 to 360 degrees. 3. The two polarizing plates sandwiching the liquid crystal cell are para-Nicol or cross-Nicol, and the polarization axis of each polarizing plate forms an angle of 45 degrees with the major axis direction of the liquid crystal molecule at the center in the depth direction of the liquid crystal cell. The method according to claim 1 or 2, wherein
A color liquid crystal display device described in. 4. The color liquid crystal display device according to claim 1, wherein the liquid crystal layer is driven by a TFT. 5. A reflecting plate is provided on the outside of one of the polarizing plates, and any one of claims 1 to 4 is provided.
A color liquid crystal display device described in the item.