JPH0756146A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the transmissivity of light and to sufficiently enhance the brightness of a display by coloring the transmitted light without using a color filter. CONSTITUTION:A TN type liquid crystal cell 10, a phase difference plate 20, three polarizing plates 21, 22 and 23 and a reflecting plate 24 are laminated in the order of the plate 24, the lower polarizing plate 21, the cell 10, the intermediate polarizing plate 22, the plate 20 and the upper polarizing plate 23. Besides, the plates 21 and 22 are arranged by almost orthogonally crossing the transmitting axes thereof or making them almost in parallel. Then, the plate 20 is provided by obliquely deviating the lag axis thereof by a prescribed angle with respect to the transmitting axes of the plates 22 and 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device capable of obtaining a colored display.

[0002]

2. Description of the Related Art Conventionally, as a color liquid crystal display device capable of obtaining a colored display, one which colors transmitted light by using a color filter has been used. This color liquid crystal display device comprises a liquid crystal cell provided with a color filter and a pair of polarizing plates arranged with the liquid crystal cell sandwiched therebetween. As the liquid crystal cell, generally, a pair of transparent substrates having transparent electrodes formed thereon. A liquid crystal is enclosed between the substrates, and the molecules of the liquid crystal are twist-aligned between the two substrates at a twist angle of about 90 °.
An N-type liquid crystal cell is used, and the pair of polarizing plates are provided such that their transmission axes are substantially orthogonal to each other or substantially parallel to each other.

[0003]

However, since the above-mentioned conventional color liquid crystal display device colors the transmitted light by using the color filter, it has a problem that the light transmittance is low and therefore the display is dark. .

This is due to the absorption of light by the color filter. Since the color filter also absorbs light in the wavelength band corresponding to the color with a considerably high absorptivity, the colored light passing through the color filter is The light has a significantly reduced amount of light as compared with the light in the wavelength band before entering the color filter, and the display becomes dark.

There are two types of liquid crystal display devices, a transmissive type that uses light from a backlight arranged on the back surface side of the liquid crystal display device, and a light that passes through the liquid crystal display device using external light on the back surface side. There is a reflective type that reflects the light with a reflector placed on the display, but when the conventional color liquid crystal display device is a reflective type, the light that enters from the surface side, is reflected by the reflector, and goes out to the surface side. Since it passes through the color filter twice to reduce the light quantity doubly, the display becomes quite dark and almost unusable as a display device.

An object of the present invention is to provide a color liquid crystal display device capable of coloring transmitted light without using a color filter to increase the light transmittance and sufficiently increase the brightness of display. It is a thing.

[0007]

In a color liquid crystal display device of the present invention, a liquid crystal is enclosed between a pair of transparent substrates having transparent electrodes, and molecules of the liquid crystal are twisted between the two substrates at a twist angle of about 90 °. An oriented TN liquid crystal cell is used, and the first invention is to provide the liquid crystal cell, a retardation plate, and three polarizing plates, a first polarizing plate, a liquid crystal cell,
A second polarizing plate, a retardation plate, and a third polarizing plate are laminated in this order, and at least the transmission axes of the first polarizing plate and the second polarizing plate are substantially orthogonal or substantially parallel to each other. In addition, the retardation plate is provided such that its slow axis is slanted by a predetermined angle with respect to the transmission axes of the second polarizing plate and the third polarizing plate.

A second aspect of the present invention includes the liquid crystal cell, the phase plate, the two polarizing plates, and the reflection plate, the reflection plate, the retardation plate, the first polarization plate, the liquid crystal cell, and the second polarization plate. The polarizing plates are laminated in this order, and the two polarizing plates are provided such that their transmission axes are substantially orthogonal or substantially parallel to each other, and the retardation plate has the slow axis of the first polarizing plate. The polarizing plate is obliquely shifted by a predetermined angle with respect to the transmission axis of the polarizing plate. In the first and second inventions, it is desirable that the deviation angle between the transmission axis of the polarizing plate and the slow axis of the retardation plate is 45 ± 5 °.

[0009]

The present invention controls the transmission of light by applying a voltage to the liquid crystal cell and colors the transmitted light by utilizing the polarization effect of the retardation plate. The color liquid crystal display of the first invention In the device, linearly polarized light that has entered through one of the second and third polarizing plates sandwiching the retardation plate is changed in polarization state by its polarizing action while passing through the retardation plate. Of the light incident on the other polarizing plate, only the wavelength light of the polarization component which is transmitted through the other polarizing plate is transmitted through this polarizing plate and becomes colored light.

On the other hand, linearly polarized light that has passed through one of the first and second polarizing plates that sandwich the liquid crystal cell is incident on the liquid crystal cell, and the light that has passed through this liquid crystal cell is the other polarized light. Incident on the plate. The alignment state of liquid crystal molecules in the liquid crystal cell is
Depending on the voltage applied between the electrodes of both substrates, it changes into a twist alignment state and a rising alignment state, and when the liquid crystal molecules are in the twist alignment state, the linearly polarized light incident on the liquid crystal cell has almost the same polarization direction in the liquid crystal layer. When the liquid crystal molecules are rotated by 90 ° and oriented vertically, the linearly polarized light that has entered the liquid crystal cell exits the liquid crystal cell without being subjected to the optical rotation effect. Therefore, one of these lights passes through the other polarizing plate. The other light is absorbed by the other polarizing plate.

Since the light emitted from the liquid crystal display device is colored light due to the polarization effect of the retardation plate, colored display by colored bright display and "black" dark display can be obtained. .

Further, the color liquid crystal display device of the second invention is of a reflection type in which light incident from the outside is reflected by a reflection plate to display, and in this color liquid crystal display device, a retardation plate is sandwiched. Since the first polarizing plate and the reflecting plate are arranged in, the linearly polarized light that has entered through the first polarizing plate can change its polarization state by the polarizing action of the retardation plate and is reflected by the reflecting plate. In the process of passing through the retardation plate again, the polarization state is further changed and the light is incident on the first polarizing plate, and of the light, only the wavelength light of the polarization component that passes through the first polarizing plate passes through this polarizing plate. It passes through and becomes colored light.

Further, in this color liquid crystal display device, the light enters the liquid crystal cell through the second polarizing plate arranged on the side opposite to the reflection plate, and passes through the liquid crystal cell, and the first polarizing plate passes through. Incident on the first polarizing plate is transmitted through or absorbed by the first polarizing plate according to the alignment state of liquid crystal molecules of the liquid crystal cell, and the transmitted light passing through the first polarizing plate is reflected through the retardation plate. The colored light which is reflected by the plate, passes through the retardation plate again, enters the first polarizing plate, and passes through the first polarizing plate, and exits through the liquid crystal cell and the second polarizing plate. Therefore, also in this liquid crystal display device, a color display including a colored bright display and a "black" dark display can be obtained.

That is, in the color liquid crystal display devices of the first and second inventions, the transmitted light is colored without using the color filter by utilizing the polarization effect of the retardation plate. Since the amount of light is almost the same as the amount of light in the wavelength band that becomes the colored light in the light incident on the display device, it is possible to increase the transmittance of light and sufficiently increase the brightness of the display. it can.

In the first and second aspects of the invention, when the deviation angle between the transmission axis of the polarizing plate and the slow axis of the retardation plate is 45 ± 5 °, the coloring effect of the retardation plate causes coloring. The effect can be satisfactorily obtained.

[0016]

【Example】

[First Embodiment of the First Invention] A first embodiment of the first invention will be described below with reference to FIGS. The color liquid crystal display device of this embodiment is of a reflective type.

FIG. 1 is a sectional view of a color liquid crystal display device. This color liquid crystal display device has one TN type liquid crystal cell 10, one retardation plate 20, and three polarizing plates 21, 2.
2, 23 and one reflector 24. These are a reflective plate 24, a first polarizing plate (hereinafter, referred to as lower polarizing plate) 21, a liquid crystal cell 10, a second polarizing plate (hereinafter, intermediate) from the back surface side (lower side in FIG. 1) of the liquid crystal display device. A polarizing plate) 22, a retardation plate 20, and a third polarizing plate (hereinafter referred to as an upper polarizing plate) 23 are laminated in this order.

The liquid crystal cell 10 includes a pair of upper and lower transparent substrates 11 and 12 on which transparent electrodes 13 and 14 are formed and alignment films 15 and 16 are formed on the transparent electrodes 13 and 14, similar to the generally used TN type liquid crystal cell. Joined via a frame-shaped sealing material 17,
A liquid crystal 18 is enclosed in a region surrounded by the sealing material 17 between the two substrates 11 and 12, and the horizontal alignment films 15 and 16 on the two substrates 11 and 12 are aligned in directions substantially orthogonal to each other. The molecules of the liquid crystal 18 are twist-aligned between the substrates 11 and 12 at a twist angle of about 90 °. The liquid crystal cell 10 is of a segment display type, for example, and includes a transparent electrode 13 formed on the upper substrate 11.
Is a common electrode, and the transparent electrode 14 formed on the lower substrate 12 is a plurality of segment electrodes having a shape corresponding to a display pattern.

The lower polarizing plate 21 and the intermediate polarizing plate 22 sandwiching the liquid crystal cell 10 are arranged such that their transmission axes are substantially orthogonal to each other or substantially parallel to each other, and the retardation plate 20 has its slow phase. The axes are provided so as to be slanted by a predetermined angle with respect to the transmission axes 23a, 22a of the upper polarizing plate 23 and the intermediate polarizing plate 22 which sandwich the retardation plate 20.

FIG. 2 is a plan view showing the alignment direction of the liquid crystal molecules of the liquid crystal cell 10, the transmission axes of the polarizing plates 21, 22 and 23, and the slow axis of the retardation plate 20, 11a being the liquid crystal. Liquid crystal molecule alignment direction on the upper substrate 11 side of the cell 10, 12
a is a liquid crystal molecule alignment direction on the lower substrate 12 side of the liquid crystal cell 10.

As shown in FIG. 2, liquid crystal molecule alignment directions 11a and 12a on both substrates 11 and 12 side of the liquid crystal cell 10 are formed.
Are displaced from each other by approximately 90 °, and the molecules of the liquid crystal 18 have their twisted directions as indicated by an arrow T in the figure.
From the 2 side toward the upper substrate 11 side, approximately 90 clockwise in the figure.
The twist orientation is at a twist angle of °.

Further, in FIG. 2, 21a is a lower polarizing plate 2.
1 is a transmission axis, 22a is a transmission axis of the intermediate polarizing plate 22, 23a
Is the transmission axis of the upper polarizing plate 23, and in this embodiment, the lower polarizing plate 21 and the intermediate polarizing plate 22 have their transmission axes 21a, 2
2a are arranged so as to be orthogonal to each other, and the upper polarizing plate 23 is arranged such that its transmission axis 23a is parallel to the transmission axis 22a of the intermediate polarizing plate 22.

The lower polarizing plate 21 and the intermediate polarizing plate 22.
Of the transmission axes 21a and 22a of the liquid crystal and the lower substrate 12 of the liquid crystal cell 10.
Direction 12 of liquid crystal molecules on the substrate side and the upper substrate 11 side
a and 11a are orthogonal to each other as shown in FIG. 2 or are parallel to each other.

Further, in FIG. 2, reference numeral 20a denotes a slow axis of the retardation plate 20, and in this embodiment, the retardation plate 20 has the slow axis 20a as the transmission axis 23 of the upper polarizing plate 23.
It is provided at an angle of 45 ° with respect to a.

The color liquid crystal display device of this embodiment controls the transmission of light by applying a voltage to the liquid crystal cell 10 and colors the transmitted light by utilizing the polarization effect of the retardation plate 20. Light incident from the outside (natural light or light from an illumination light source) passes through the upper polarizing plate 23, the retardation plate 20, the intermediate polarizing plate 22, the liquid crystal cell 10, and the lower polarizing plate 21, and is reflected by the reflecting plate 24. Lower polarizing plate 21 and liquid crystal cell 1 again
0, the intermediate polarizing plate 22, the phase difference plate 20, and the upper polarizing plate 23, and the light is emitted to the front surface side.

In this color liquid crystal display device, the linearly polarized light that has entered through the upper polarizing plate 23 sandwiching the retardation plate 20 and the upper polarizing plate 23 of the intermediate polarizing plates 22 is the retardation plate 2.
In the process of passing through 0, the polarization state is changed by the polarization action of the retardation plate 22 and is incident on the intermediate polarizing plate 22. Of the light, only the wavelength light of the polarization component which is transmitted through the intermediate polarizing plate 22 is in the intermediate range. The colored light is transmitted through the polarizing plate 22.

The coloring of the transmitted light due to the polarization effect of the retardation plate 20 will be explained. Although the light from the outside is linearly polarized by the upper polarizing plate 23 and enters the retardation plate 20,
Since the slow axis 20a of the retardation plate 20 is obliquely displaced with respect to the transmission axis 23a of the upper polarizing plate 23, that is, the polarization direction of the linearly polarized light passing through the upper polarizing plate 23, The incident linearly polarized light passes through the phase difference plate 20, and the phase difference plate 2 with respect to the transmission axis 23 a of the upper polarizing plate 23.
The retardation plate 20 emits a non-linearly polarized light (elliptically polarized light) due to a polarization effect according to the shift angle of the slow axis 20a of 0 and the retardation Re of the retardation plate 20.

When the non-linearly polarized light which has been polarized by the phase difference plate 20 enters the intermediate polarizing plate 22, the wavelength light of the polarization component of the non-linearly polarized light which is transmitted through the intermediate polarizing plate 22. Passes through the intermediate polarizing plate 22,
Light of other wavelengths is absorbed by the intermediate polarizing plate 22, so that the light (linearly polarized light) that has passed through the intermediate polarizing plate 22 becomes colored light.

On the other hand, the liquid crystal cell 10 includes the liquid crystal cell 1
The linearly polarized light that has passed through the intermediate polarizing plate 22 of the lower polarizing plate and the intermediate polarizing plate 22 sandwiching 0 is incident, and the light that has passed through the liquid crystal cell 20 is incident on the lower polarizing plate 21.

The alignment state of the liquid crystal molecules of the liquid crystal cell 20 depends on the voltage applied between the electrodes 13 and 14 of both substrates 11 and 12, and the initial twist alignment state and the substrate 1
When the liquid crystal molecules change to a rising alignment state that rises almost perpendicularly to the 1st and 12th planes and the liquid crystal molecules are in the twisted alignment state, the linearly polarized light incident on the liquid crystal cell 10 rotates the polarization direction by about 90 ° in the liquid crystal layer. When the liquid crystal molecules are vertically oriented, the linearly polarized light that has entered the liquid crystal cell 10 exits the liquid crystal cell 10 without being optically rotated, so that one of these lights passes through the lower polarization plate 21, The other light is absorbed by the lower polarizing plate 21.

That is, in this embodiment, the lower polarizing plate 21
Since the transmission axes 21a and 22a of the intermediate polarizing plate 22 and the intermediate polarizing plate 22 are orthogonal to each other, the light polarized in the liquid crystal cell 10 by approximately 90 ° is transmitted through the lower polarizing plate 21 and has an optical rotation effect. The light emitted from the liquid crystal cell 10 without being received (the same light as the linearly polarized light passing through the intermediate polarizing plate 22) is absorbed by the lower polarizing plate 21.

The light transmitted through the lower polarizing plate 21 is reflected by the reflecting plate 24 and is emitted to the front surface side of the liquid crystal display device. The emitted light is colored by the polarization effect of the retardation plate 20. Since it is a bright light, a color display by a colored bright display and a “black” dark display can be obtained.

In this liquid crystal display device, the reflection plate 24
Although the light reflected by the light passes through the retardation plate 20 again in the process of being emitted to the front surface side of the liquid crystal display device, the light reflected by the reflection plate 24 becomes elliptically polarized light due to the polarization action of the retardation plate 20 described above. It is only the wavelength light of the polarization component that has passed through the intermediate polarizing plate 22 of the emitted light, and this light hardly receives the polarization action when passing through the retardation plate 20 again. However, of the reflected light, light having a very small wavelength component at the end of the wavelength range is polarized in the process of passing through the retardation plate 20 and absorbed by the upper polarizing plate 23. The colored light that passes through and exits becomes light having a higher color purity than the colored light reflected by the reflection plate 24.

As described above, the color liquid crystal display device has
The transmitted light is colored without using a color filter. Therefore, the amount of colored light is almost the same as the amount of light in the wavelength band that becomes the colored light among the light incident on the display device. The brightness of the display can be made sufficiently high by increasing the transmittance.

That is, the conventional color liquid crystal display device is
Since the transmitted light is colored by the color filter, the light amount of the colored light passing through the color filter is considerably reduced as compared with the light amount in the wavelength band which becomes the colored light of the light incident on the display device. In the color liquid crystal display device of the embodiment, such a decrease in the light amount hardly occurs.

Therefore, although the color liquid crystal display device of the above-mentioned embodiment is of a reflection type, the brightness of the display is sufficient, and the color display is significantly brighter than the conventional color liquid crystal display device. can get.

The color of the colored light in this color liquid crystal display device includes the retardation Re of the retardation plate 20 and the slow axis 20 of the retardation plate 20 with respect to the transmission axis 23a of the upper polarizing plate 23.
It is determined by the shift angle of a and the direction of the transmission axis 22a of the intermediate polarizing plate 22. For example, the retardation Re of the retardation plate 20 is 450 nm, and the slow axis 20a of the retardation plate 20 relative to the transmission axis 23a of the upper polarizing plate 23 is When the shift angle is 45 ° and the direction of the transmission axis 22a of the intermediate polarizing plate 22 is parallel to the transmission axis 23a of the upper polarizing plate 23, the colored light is “blue”.

The liquid crystal display device of the above embodiment is a negative display type in which the transmission axes 21a and 22a of the lower polarizing plate 21 and the intermediate polarizing plate 22 which sandwich the liquid crystal cell 10 are orthogonal to each other. The display pattern is “black” in the background of
Since it is displayed in, the display contrast is also good.

Although the liquid crystal display device of the first embodiment is of a negative display type, the color liquid crystal display device has a lower polarizing plate 21 and an intermediate polarizing plate 2 which sandwich the liquid crystal cell 10.
It may be of a positive display type in which the two transmission axes 21a and 22a are substantially parallel to each other.

FIG. 3 shows a second embodiment of the first invention and the alignment direction of the liquid crystal molecules of the liquid crystal cell 10 and each polarizing plate 2.
FIG. 3 is a plan view showing transmission axes of 1, 2, 23 and a slow axis of the retardation plate 20. In this embodiment, liquid crystal molecule alignment directions 11a, 12 on both substrates 11, 12 side of the liquid crystal cell 10 are shown.
a and the transmission axes 22 of the intermediate polarizing plate 22 and the upper polarizing plate 23.
The directions of a and 23a and the direction of the slow axis 20a of the retardation plate 20 are the same as those in the first embodiment, and the transmission axis 21a of the lower polarizing plate 21 is parallel to the transmission axis 22a of the intermediate polarizing plate 22. It is a thing.

That is, the color liquid crystal display device of the second embodiment is of a positive display type, and for example, when the retardation Re of the retardation plate 20 is 450 nm, "blue" is present in the "black" background. The display pattern of is displayed with good contrast.

Further, in the first and second embodiments, the transmission axes 22a and 23a of the intermediate polarizing plate 22 and the upper polarizing plate 21 which are arranged with the retardation plate 20 sandwiched therebetween are parallel to each other. Transmission axis 2 of polarizing plate 22 and upper polarizing plate 21
2a and 23a may be substantially orthogonal to each other.

FIG. 4 shows the third embodiment of the first invention, and the liquid crystal molecule alignment direction of the liquid crystal cell 10 and each polarizing plate 2.
2 is a plan view showing the transmission axes of 1, 22, 23 and the slow axis of the retardation plate 20. In this embodiment, the transmission axes 22a, 23a of the intermediate polarizing plate 22 and the upper polarizing plate 21 are substantially orthogonal to each other. It was made.

This color liquid crystal display device is of a negative display type, and in this embodiment, liquid crystal molecule alignment directions 11a and 12a on both substrates 11 and 12 side of the liquid crystal cell 10 are used.
And the transmission axes 21 of the lower polarizing plate 21 and the intermediate polarizing plate 22.
The directions of a and 22a and the direction of the slow axis 20a of the phase difference plate 20 are the same as those in the first embodiment, and the transmission axis 23a of the upper polarizing plate 23 is orthogonal to the transmission axis 22a of the intermediate polarizing plate 22. There is.

The color of the colored light in the third embodiment is
For example, the retardation Re of the retardation plate 20 is 450 nm.
In this case, the display pattern is “orange”, and the display pattern of “black” is displayed with good contrast in the background of “orange”.

FIG. 5 shows a fourth embodiment of the first aspect of the invention, in which the liquid crystal molecule alignment direction of the liquid crystal cell 10, the transmission axes of the respective polarizing plates 21, 22, 23, and the phase difference plate 20. It is a plan view showing a slow axis, and in this embodiment also, the transmission axes 22a and 23a of the intermediate polarizing plate 22 and the upper polarizing plate 21 are made substantially orthogonal to each other.

This color liquid crystal display device is of a positive display type. In this embodiment, liquid crystal molecule alignment directions 11a and 12a on both substrates 11 and 12 side of the liquid crystal cell 10 are used.
And the transmission axes 21 of the lower polarizing plate 21 and the intermediate polarizing plate 22.
The directions of a and 22a and the slow axis 20a of the retardation plate 20 are the same as those in the second embodiment, and the transmission axis 23a of the upper polarizing plate 23 is parallel to the transmission axis 22a of the intermediate polarizing plate 22. There is.

The color of the colored light in the fourth embodiment is also
For example, the retardation Re of the retardation plate 20 is 450 nm.
In this embodiment, the display pattern of "orange" is displayed with good contrast in the background of "black".

In the first to fourth embodiments, the transmission axes 22a and 23a of the intermediate polarizing plate 22 and the upper polarizing plate 23 which sandwich the retardation plate 20 are made orthogonal to each other or parallel to each other.
The slow axis 20a of the retardation plate 20 is slanted at an angle of 45 ° with respect to the transmission axes 22a and 23a of the polarization plates 22 and 23, but the transmission axes 22a of the intermediate polarization plate 22 and the upper polarization plate 23 are shifted. , 23a may each have any orientation, and
The shift angle of the slow axis 20a of the retardation plate 20 with respect to the transmission axis 23a of the upper polarizing plate 23 and the transmission axis 22a of the intermediate polarizing plate 22.
The shift angle of the slow axis 20a of the retardation plate 20 with respect to may be arbitrary.

However, the upper polarizing plate 23 and the intermediate polarizing plate 2
The shift angle of the slow axis 20a of the retardation plate 20 with respect to the two transmission axes 23a and 22a is preferably in the range of 45 ± 5 °. If the shift angle is selected in this range, the retardation plate 20 is colored by the polarization effect. The effect can be satisfactorily obtained.

In each of the above embodiments, the liquid crystal cell 10 is provided between the lower polarizing plate 21 and the intermediate polarizing plate 22, and the retardation plate 20 is provided between the intermediate polarizing plate 22 and the upper polarizing plate 23. However, the arrangement of the liquid crystal cell 10 and the retardation plate 20 may be reversed, and even in that case, at least the first polarizing plate and the second polarizing plate sandwiching the liquid crystal cell have their transmission axes substantially orthogonal to each other. The retardation plates are arranged in parallel or substantially parallel to each other, and the slow axis of the retardation plate is at a predetermined angle (preferably 45 ± 5) with respect to the transmission axes of the second polarizing plate and the third polarizing plate which sandwich the retardation plate.
°) It should be installed at an angle.

Further, although the color liquid crystal display device of the above-mentioned embodiment is of the reflection type in which the reflection plate 24 is arranged on the back surface side, the first invention can also be applied to the transmission type color liquid crystal display device. .

[Embodiment of the Second Invention] Next, an embodiment of the second invention will be described with reference to FIGS. 6 and 7. Figure 6
1 is a cross-sectional view of a color liquid crystal display device. This color liquid crystal display device includes one TN type liquid crystal cell 10, one retardation plate 20, two polarizing plates 21 and 22, and one reflection plate. And a plate 24. These are a reflective plate 24, a retardation plate 20, a first polarizing plate (hereinafter, referred to as lower polarizing plate) 21, a liquid crystal cell 10, and a second polarized light from the back surface side (lower side in FIG. 1) of the liquid crystal display device. Plate (hereinafter referred to as upper polarizing plate) 2
It is laminated in the order of 2. The liquid crystal cell 10 is
Since the structure is the same as that shown in FIG. 1, the description thereof will be omitted by giving the same symbols to the drawing.

The two polarizing plates 21 and 22 are provided so that their transmission axes are substantially orthogonal or substantially parallel to each other, and the retardation plate 20 has the slow axis of the lower polarizing plate 21. It is provided so as to be slanted at a predetermined angle with respect to the transmission axis.

FIG. 7 is a plan view showing the alignment direction of liquid crystal molecules of the liquid crystal cell 10, the transmission axes of the polarizing plates 21, 22 and 23, and the slow axis of the retardation plate 20, 11a being the liquid crystal. Liquid crystal molecule alignment direction on the upper substrate 11 side of the cell 10, 12
a is a liquid crystal molecule alignment direction on the lower substrate 12 side of the liquid crystal cell 10.

As shown in FIG. 7, liquid crystal molecule alignment directions 11a and 12a on both substrates 11 and 12 side of the liquid crystal cell 10 are formed.
Are displaced from each other by approximately 90 °, and the molecules of the liquid crystal 18 have their twisted directions as indicated by an arrow T in the figure.
From the 2 side toward the upper substrate 11 side, approximately 90 clockwise in the figure.
The twist orientation is at a twist angle of °.

Further, in FIG. 7, reference numeral 21a denotes the lower polarizing plate 2.
1 is a transmission axis, and 22a is a transmission axis of the upper polarizing plate 22, and in this embodiment, the lower polarizing plate 21 and the upper polarizing plate 22 are arranged such that their transmission axes 21a and 22a are orthogonal to each other. ing.

The transmission axes 21a and 22a of the lower polarizing plate 21 and the upper polarizing plate 22 and the liquid crystal molecule alignment directions 12a on the lower substrate 12 side and the upper substrate 11 side of the liquid crystal cell 10, respectively.
11a are parallel to each other as shown in FIG. 7 or orthogonal to each other.

Further, in FIG. 7, reference numeral 20a denotes a slow axis of the retardation plate 20. In this embodiment, the retardation plate 20 has a slow axis 20a which is the transmission axis 21 of the lower polarizing plate 21.
It is provided at an angle of 45 ° with respect to a.

This color liquid crystal display device is of a reflection type in which light incident from the surface side (natural light or light from an illumination light source) is reflected by the reflection plate 24 and displayed, and the voltage applied to the liquid crystal cell 10 is changed. The transmission of light is controlled by application, and the transmitted light is colored by utilizing the polarization effect of the retardation plate 20.

In this liquid crystal display device, light incident from the outside enters the liquid crystal cell 10 through the upper polarizing plate 22 arranged on the side opposite to the reflection plate 24, and the liquid crystal cell 1
Light incident on the lower polarizing plate 21 through 0 passes through the liquid crystal cell 10
Depending on the alignment state of the liquid crystal molecules, the light is transmitted through or absorbed by the lower polarizing plate 21.

The transmitted light that has passed through the lower polarizing plate 21 passes through the retardation plate 20 and is reflected by the reflecting plate 24, and again passes through the retardation plate 20 and enters the lower polarizing plate 21. The light transmitted through the lower polarizing plate 21 becomes colored light.

That is, in this liquid crystal display device,
The linearly polarized light that has entered the retardation plate 20 through the lower polarizing plate 21 is changed in polarization state by the polarization action of the retardation plate 22 in the process of passing through the retardation plate 20.
The light is reflected by, and is changed in polarization state in the process of passing through the retardation plate 20 again, and is incident on the lower polarizing plate 21.
Only the wavelength light of the polarization component that passes through the lower polarizing plate 21 passes through the lower polarizing plate 21 to become colored light, and this colored light passes through the liquid crystal cell 10 and the upper polarizing plate 22 and the surface side of the liquid crystal display device. To a color display by a colored bright display and a "black" dark display.

Thus, the color liquid crystal display device described above
The transmitted light is colored without using a color filter. Therefore, the amount of the colored light is almost the same as the amount of the light in the wavelength band that becomes the colored light among the light incident on the display device. However, even if it has a high light transmittance, a color display much brighter than that of a conventional color liquid crystal display device can be obtained.

The color of the colored light in this color liquid crystal display device includes the retardation Re of the retardation plate 20 and the slow axis 20 of the retardation plate 20 with respect to the transmission axis 21a of the lower polarizing plate 21.
When the shift angle of the slow axis 20a of the retardation plate 20 with respect to the transmission axis 21a of the lower polarizing plate 21 is 45 °, the retardation Re of the retardation plate 20 is Re = 450 nm. In case of "blue", Re = 55
It is "green" at 0 nm.

The liquid crystal display device of the above embodiment is of a negative display type in which the transmission axes 21a and 22a of the lower polarizing plate 21 and the upper polarizing plate 22 which sandwich the liquid crystal cell 10 are orthogonal to each other, and are "blue". Alternatively, since the display pattern is displayed in "black" on the "green" background, the display contrast is also good.

Although the liquid crystal display device of the above embodiment is of a negative display type, the color liquid crystal display device is
It may be a positive display type in which the transmission axes 21a and 22a of the lower polarizing plate 21 and the upper polarizing plate 22 that sandwich the liquid crystal cell 10 are substantially parallel to each other.

In the above embodiment, the slow axis 20a of the retardation plate 20 is 45 ° with respect to the transmission axis 21a of the lower polarizing plate 21.
Although the angle is shifted obliquely, the shift angle of the slow axis 20a of the retardation plate 20 with respect to the transmission axis 21a of the lower polarizing plate 21 may be arbitrary. However, in order to obtain a good coloring effect due to the polarization effect of the retardation plate 20, the transmission axis 2 of the lower polarizing plate 21 is required.
The deviation angle of the slow axis 20a of the phase difference plate 20 with respect to 1a is 4
It is desirable to select within the range of 5 ± 5 °.

[0069]

According to the color liquid crystal display device of the first invention, the T
An N-type liquid crystal cell, a retardation plate, and three polarizing plates, a first polarizing plate, a liquid crystal cell, a second polarizing plate, a retardation plate, and a third polarizing plate.
The polarizing plates are laminated in this order, and at least the first polarizing plate and the second polarizing plate are arranged such that their transmission axes are substantially orthogonal to each other or are substantially parallel to each other.
Since the retardation plate is provided such that its slow axis is slanted by a predetermined angle with respect to the transmission axes of the second polarizing plate and the third polarizing plate, the transmitted light is colored without using a color filter. As a result, the light transmittance can be increased and the display brightness can be sufficiently increased.

The color liquid crystal display device of the second invention comprises a TN type liquid crystal cell, a phase plate, two polarizing plates,
A reflection plate, a reflection plate, a retardation plate, a first polarization plate, a liquid crystal cell, and a second polarization plate, which are laminated in this order, and the transmission axes of the two polarization plates are substantially orthogonal to each other. The retardation plate is provided in such a manner that it is provided in a substantially parallel manner, and the retardation plate is provided such that the slow axis thereof is slanted by a predetermined angle with respect to the transmission axis of the first polarizing plate. Therefore, a color filter is not used. Color the transmitted light to increase the light transmittance,
The display brightness can be made sufficiently high.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a color liquid crystal display device showing a first embodiment of the first invention.

FIG. 2 is a plan view showing a liquid crystal molecule alignment direction of a liquid crystal cell, a transmission axis of each polarizing plate, and a slow axis of a retardation plate.

FIG. 3 is a plan view showing a liquid crystal molecule alignment direction of a liquid crystal cell, a transmission axis of each polarizing plate, and a slow axis of a retardation plate, showing a second embodiment of the first invention.

FIG. 4 is a plan view showing a liquid crystal molecule alignment direction of a liquid crystal cell, a transmission axis of each polarizing plate, and a slow axis of a retardation plate, showing a third embodiment of the first invention.

FIG. 5 is a plan view showing a liquid crystal molecule alignment direction of a liquid crystal cell, a transmission axis of each polarizing plate, and a slow axis of a retardation plate, showing a fourth embodiment of the first invention.

FIG. 6 is a sectional view of a color liquid crystal display device showing an embodiment of the second invention.

FIG. 7 is a plan view showing a liquid crystal molecule alignment direction of a liquid crystal cell, a transmission axis of each polarizing plate, and a slow axis of a retardation plate.

[Explanation of symbols]

 10 ... Liquid crystal cell 11, 12 ... Transparent substrate 11a ... Liquid crystal molecule alignment direction on upper substrate side 12a ... Liquid crystal molecule alignment direction on lower substrate side 13, 14 ... Transparent electrode 15, 16 ... Alignment film 18 ... Liquid crystal 20 ... Retardation plate 20a ... Slow axis 21, 22, 23 ... Polarizing plate 21a, 22a, 23a ... Transmission axis 24 ... Reflector

Claims (3)

[Claims] 1. A liquid crystal is sealed between a pair of transparent substrates on which transparent electrodes are formed, and the molecules of the liquid crystal are almost 90
A liquid crystal cell twist-aligned at a twist angle of 90 °, a retardation plate, and three polarizing plates, a first polarizing plate, a liquid crystal cell,
A second polarizing plate, a retardation plate, and a third polarizing plate are laminated in this order, and at least the transmission axes of the first polarizing plate and the second polarizing plate are substantially orthogonal or substantially parallel to each other. And the retardation plate is provided such that the slow axis thereof is slanted by a predetermined angle with respect to the transmission axes of the second polarizing plate and the third polarizing plate. . 2. A liquid crystal is sealed between a pair of transparent substrates on which transparent electrodes are formed, and the molecules of the liquid crystal are almost 90
A liquid crystal cell twist-aligned at a twist angle of °, a phase plate, two polarizing plates, and a reflecting plate, a reflecting plate, a retardation plate, a first polarizing plate, a liquid crystal cell, and a second polarizing plate. And the transmission axes of the two polarizing plates are set to be substantially orthogonal or substantially parallel to each other, and the retardation plate has the slow axis of the first polarizing plate. A color liquid crystal display device, wherein the color liquid crystal display device is provided at a predetermined angle with respect to the transmission axis of the device. 3. The color liquid crystal display device according to claim 1, wherein the deviation angle between the transmission axis of the polarizing plate and the slow axis of the retardation plate is 45 ± 5 °.