JP2003114428A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome such a fault that the visibility dropps extremely because of reflected light quantity to be used in a display in the case of dark ambient light regarding a reflective liquid crystal display device and on the other hand, contrary to this case, to solve such a problem that the visibility dropps in fine weather with very bright ambient light regarding a transmissive liquid crystal display device. SOLUTION: The liquid crystal display device is provided with one substrate 1 having a region with a reflecting function and a region with a transmitting function, the other substrate 2 having a counter electrode 4 formed thereon and a liquid crystal layer 5 sandwiched between the one substrate 1 and the other substrate 2, and has a first polarizing means 6 disposed on a surface of the other substrate 2 opposite to the liquid crystal layer 5, a second polarizing means 9 disposed on a surface of the one substrate 1 opposite to the liquid crystal layer 5, a first optical retardation plate 7 disposed between the first polarizing means 6 and the liquid crystal layer 5 and a second optical retardation plate 10 disposed between the second polarizing means 9 and the liquid crystal layer 5. The first optical retardation plate 7 and the second optical retardation plate 10 consist of quarter-wave plates. The angle which a transmission axis of the first polarizing means 6 forms with a slow axis of the first optical retardation plate 7 is 45 deg. and further the angle which a transmission axis of the second polarizing means 9 forms with a slow axis of the second optical retardation plate 10 is 45 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device used in office automation equipment such as word processors and personal computers, portable information equipment such as electronic notebooks, and camera integrated VTRs equipped with a liquid crystal monitor. The present invention relates to a liquid crystal display device having both a reflection type and a transmission type.

[0002]

2. Description of the Related Art A liquid crystal display, unlike a CRT (CRT) or an EL (electroluminescence), does not emit light by itself. Therefore, a transmissive liquid crystal display device is used in which a backlight is installed on the back surface of a liquid crystal display element to illuminate it. ing.

However, since the backlight usually consumes 50% or more of the total power consumption of the liquid crystal display, a reflector is installed in place of the backlight in portable information equipment that is often used outdoors or always carried. A reflective liquid crystal display device that displays only by ambient light has also been realized.

The display mode used in the reflection type liquid crystal display device is a type using a polarizing plate such as a TN (twisted nematic) mode and an STN (super twisted nematic) mode which are widely used in the transmission type at present, and a polarization mode. A phase transition type guest-host mode capable of realizing a bright display without using a plate has been actively developed in recent years, and is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-75022 and Japanese Patent Application No. 7-228365.

[0005]

However, in the phase transition type guest-host mode, since the liquid crystal layer in which the liquid crystal molecules and the dye are dispersed is used for display by using the light absorption of the dye, a sufficient contrast cannot be obtained, and TN (twisted) is used. The display quality is significantly deteriorated as compared with a liquid crystal display device of a type using a polarizing plate such as a nematic) mode and an STN (super twisted nematic) mode.

Further, in the case of a liquid crystal display device of parallel alignment or twist alignment, liquid crystal molecules near the center of the liquid crystal layer are tilted in the direction perpendicular to the substrate surface when a voltage is applied, but liquid crystal molecules near the alignment film surface are The birefringence of the liquid crystal layer is far from 0 because it is not perpendicular to the substrate even when a voltage is applied. In the display mode in which black display is performed when a voltage is applied, sufficient black is displayed due to the birefringence of the liquid crystal layer. It is not possible to obtain sufficient contrast.

It is hard to say that the TN mode and STN mode liquid crystal display devices have sufficient display quality in terms of brightness and contrast at present, and further improvement in display quality such as higher brightness and improvement in contrast is required. ing.

Further, the reflection type liquid crystal display device has a drawback that the reflected light used for display is lowered and the visibility is extremely lowered when the ambient light is dark, whereas the transmission type liquid crystal display device is different from this. On the contrary, there is a problem that the visibility is deteriorated in a clear sky where the ambient light is very bright.

[0009]

The present invention has a first substrate having a region having a reflection function and a region having a transmission function and a second substrate having a counter electrode formed thereon. A liquid crystal display device in which a liquid crystal layer is sandwiched between the first substrate and the first polarizing means provided on a surface of the other substrate opposite to the liquid crystal layer, and a surface of the one substrate opposite to the liquid crystal layer. Between the second polarizing means and the liquid crystal layer, the first polarizing means provided between the first polarizing means and the liquid crystal layer, and the second polarizing means provided in the first polarizing means and the liquid crystal layer. A second retardation plate provided, wherein the first retardation plate and the second retardation plate are λ / 4 plates, and the transmission axis of the first polarizing means and the first retardation plate are provided. The angle formed by the retardation plate of the retardation plate is 45 °, and the transmission axis of the second polarizing means and the second phase are The angle formed by the delay axis of the difference plate is 45 °
Is a liquid crystal display device.

Further, the liquid crystal display device has one substrate having a region having a reflection function and a region having a transmission function and the other substrate having a counter electrode formed thereon, and a liquid crystal layer is sandwiched between the one substrate and the other substrate. In the liquid crystal display device, a first polarization unit provided on a surface of the other substrate opposite to the liquid crystal layer, and a second polarization means provided on a surface of the one substrate opposite to the liquid crystal layer. Means, a first retardation plate provided between the first polarizing means and the liquid crystal layer, and a second retardation plate provided between the second polarizing means and the liquid crystal layer. A liquid crystal display device having a plate, wherein the transmission axis of the first polarizing means and the transmission axis of the second polarizing means are set in the same direction.

The operation of the present invention will be described below.

A liquid crystal display device having a region having a reflection function and a region having a transmission function has a first polarizing means, a second polarizing means, a first retardation plate and a second retardation plate. As a result, in the reflection mode in which the display is performed by the reflected light in the region having the reflection function, the retardation (birefringence index) in the observer direction of the liquid crystal layer is 0 (the initial alignment state in the vertical alignment mode, the voltage in the parallel alignment mode). In the applied state), the linearly polarized light that has passed through the first polarizing means passes through the first retardation plate and the liquid crystal layer, is reflected, passes through the liquid crystal layer and the first retardation plate again, and passes through the first retardation plate. When entering the polarizing means, a dark display is possible because there are many polarization components orthogonal to the transmission axis of the first polarizing means, and if retardation occurs in the observer direction, the light is transmitted through the first polarizing means. The linearly polarized light transmitted through the first retardation plate and the liquid crystal layer When reflected and again passed through the liquid crystal layer and the first retardation plate and made incident on the first polarization means, it has a polarization component parallel to the transmission axis of the first polarization means, and thus corresponds to each retardation. Bright display with gradation is possible.

In the transmissive mode in which the transmitted light in the region having the transmissive function is used for display, if the retardation in the observer direction of the liquid crystal layer is substantially zero, the linearly polarized light passing through the second polarizing means is When entering the first polarizing means after passing through the retardation plate, the liquid crystal layer and the first retardation plate, dark display is possible because there are many polarized components orthogonal to the transmission axis of the first polarizing means, Further, when the retardation increases toward the observer, the linearly polarized light that has passed through the second polarizing means passes through the second retardation plate, the liquid crystal layer and the first retardation plate and becomes the first polarizing means. When entering, since it has a polarization component parallel to the transmission axis of the first polarization means, bright display having gradation corresponding to each retardation is possible.

Therefore, when the reflection mode and the transmission mode are used together, dark display can be performed at the same time, and even when both are used together, high contrast display is possible. Further, gradation display is possible by changing the retardation value by the voltage.

Further, since the retardations of the first retardation plate and the second retardation plate are set to the λ / 4 condition, in the reflection mode in which display is performed by the reflected light in the region having the reflection function, In the state where there is almost no birefringence due to the liquid crystal layer in the observer direction, circularly polarized light enters, is reflected by a region having a reflection function, becomes circularly polarized light with the rotation direction reversed, and passes through the first retardation plate to produce the first polarized light. The linearly polarized light is orthogonal to the transmission axis of the polarizing means. In the reflective area of this liquid crystal display device, since it functions as an optical isolator, a dark display with little light leakage is obtained.

Further, when there is birefringence due to the liquid crystal layer in the observer direction, by changing the retardation thereof, when the light incident on the first polarizing means is reflected and again enters the first polarizing means. In addition, since a polarization component parallel to the transmission axis of the first polarization means is generated and is incident, a gradation display or bright display is possible.

Next, in the transmissive mode in which the transmitted light in the region having the transmissive function is used for display, circularly polarized light is incident on the liquid crystal layer when there is almost no birefringence due to the liquid crystal layer in the observer direction, and circularly polarized light passes through the liquid crystal layer. Is stored, passes through the first retardation plate, becomes linearly polarized light orthogonal to the transmission axis of the first polarizing means, and is a dark display with little light leakage. Further, since the retardation changes when there is birefringence due to the liquid crystal layer in the observer direction, when the light incident from the second polarizing means enters the first polarizing means, it is transmitted by the first polarizing means. Since it enters as a polarization component parallel to the axis, it becomes a bright display capable of gradation display.

Therefore, even when the reflective mode and the transmissive mode are used together, the state of the liquid crystal molecules at the time of dark display is the same, and at the same time, a dark display without light leakage is possible, and the ambient light intensity does not matter. A high-contrast display is realized as a reflective type, a transmissive type, or a dual type.

Further, when the retardation of the liquid crystal layer in the reflection region remains by α, the retardation of the first retardation plate is set to the condition of (λ / 4−α), so that the parallel alignment treatment is performed. In addition, even when the remaining retardation cannot be ignored, such as a display mode or a case where the pretilt angle is large even in the vertical alignment processing, a display with high contrast is realized as a reflection type. In the reflection mode, elliptically polarized light deviated from the circularly polarized light by the amount of the remaining retardation is incident on the liquid crystal layer. The light passes through the liquid crystal layer and becomes circularly polarized light in a region having a reflection function, and is reflected to become circularly polarized light with its rotation direction reversed. When passing through the liquid crystal layer and exiting from the liquid crystal layer,
The elliptically polarized light deviates from the circularly polarized light. At this time, the elliptically polarized light is in a state in which the phase is 90 degrees different from that at the time of incidence. Therefore, when it passes through the first retardation plate, it becomes linearly polarized light that is orthogonal to the transmission axis of the first polarizing means. In the reflective area of this liquid crystal display device, since it functions as an optical isolator, a dark display with little light leakage is obtained.

Therefore, even if the remaining retardation cannot be ignored, a reflective display with high contrast can be realized.

When the reflective display is mainly used, such as when the area of the reflective electrode is larger than the area of the transmissive electrode, the retardation plate 10 shown in the embodiment may be a λ / 4 plate.

Further, when the retardation of the liquid crystal layer in the reflective region remains by α and the retardation of the liquid crystal layer in the transmissive region remains by β, the retardation of the first retardation plate is (λ / 4− In (α) condition, the retardation of the second retardation plate is set to (λ / 4- (β-α)) condition. Is large,
Even if the residual retardation cannot be ignored, high-contrast display is realized as a reflective type, a transmissive type, or a dual type. In the reflection mode, elliptically polarized light deviated from the circularly polarized light by the amount of the remaining retardation is incident on the liquid crystal layer. The light passes through the liquid crystal layer and becomes circularly polarized light in a region having a reflection function, and is reflected to become circularly polarized light with its rotation direction reversed.
When the light passes through the liquid crystal layer and exits from the liquid crystal layer, it becomes elliptically polarized light deviated from circularly polarized light. At this time, the elliptically polarized light is in a state in which the phase is 90 degrees different from that at the time of incidence. Therefore, when it passes through the first retardation plate, it becomes linearly polarized light that is orthogonal to the transmission axis of the first polarizing means. In the reflective area of this liquid crystal display device, since it functions as an optical isolator, a dark display with little light leakage is obtained.

Next, in the transmissive mode in which the transmitted light in the region having the transmissive function is used for display, when there is almost no birefringence due to the liquid crystal layer in the observer direction, when the liquid crystal layer is emitted, it is in the same state as the emitted light in the reflective mode. Second to be elliptically polarized light of
The phase difference plate is set, and the elliptically polarized light having the phase difference is incident. Therefore, when passing through the first phase difference plate, it becomes linearly polarized light orthogonal to the transmission axis of the first polarizing means, and little light leakage occurs. It becomes a dark display.

Therefore, even if the residual retardation cannot be ignored, a high contrast display can be realized as a reflective type, a transmissive type or a dual type.

The first retardation plate and the second retardation plate are λ / 4 plates, and the angle formed by the transmission axis of the first polarizing means and the first retardation plate is 45 ° and the first retardation plate is 45 °. When the angle between the transmission axis of the second polarizing means and the second retardation plate is 45 °, and the remaining retardation can be ignored,
Circularly polarized light can be incident on the liquid crystal layer with the simplest configuration.

If a vertically aligned liquid crystal layer made of a liquid crystal material exhibiting negative dielectric anisotropy is used, the birefringence of the liquid crystal layer is almost zero when no voltage is applied to the liquid crystal layer, and the birefringence of the liquid crystal layer is zero when no voltage is applied. A good black level is obtained, and the contrast of the display device is improved.

Further, by providing an optical compensation layer for compensating the influence due to the refractive index anisotropy of the liquid crystal molecules generated in the light incident direction of the liquid crystal layer and the viewing angle direction, the light incident direction of the liquid crystal layer is provided. Also, it is possible to compensate for the anisotropy of refractive index that occurs in the viewing angle direction, and prevent a decrease in contrast depending on the incident direction of light or the viewing angle direction.

If a chiral material is added to a vertically aligned liquid crystal layer made of a liquid crystal material exhibiting negative dielectric anisotropy and the liquid crystal molecules are swung when a voltage is applied, the swirling of the liquid crystal molecules when a voltage is applied is stabilized. It can be Further, when the rubbing directions of the upper and lower substrates are not in the same direction, the loci of the alignment treatment are not in the same direction, so that the streaks are less visible.

Further, if the liquid crystal layer is twisted by 90 °, retardation occurs in the tilt direction of the liquid crystal molecules when the liquid crystal layer is oriented at an angle of several degrees with respect to the substrate in order to prevent disclination when a voltage is applied. However, since the tilted directions of the liquid crystal molecules near the substrate form an angle of 90 ° with each other near the upper and lower substrates, the retardation that occurs can be canceled and a black display with less leakage light can be obtained.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIG.

The reflective electrode 3 is formed on the substrate 1 with a material having a high reflectance such as Al and Ta, the counter electrode 4 is formed on the substrate 2, and the negative dielectric constant is anisotropic between the reflective electrode 3 and the counter electrode 4. A liquid crystal layer 5 made of a liquid crystal material having a property is sandwiched.

Vertically oriented alignment films (not shown) are formed on the surfaces of the reflective electrode 3 and the counter electrode 4 in contact with the liquid crystal layer 5.
Are formed, and after the alignment film is applied, at least one of the alignment films is subjected to alignment treatment such as rubbing.

The liquid crystal molecules of the liquid crystal layer 5 have a tilt angle of about 0.1 ° to 5 ° with respect to the vertical direction of the substrate surface by an alignment treatment such as rubbing on a vertical alignment film.

Since a liquid crystal material having a negative dielectric anisotropy is used for the liquid crystal layer 5, when a voltage is applied between the reflective electrode 3 and the counter electrode 4, the liquid crystal molecules are parallel to the substrate surface. Lean toward you.

Here, the reflective electrode 3 is used as an electrode for applying a voltage to the liquid crystal layer 5, but a film different from the reflective electrode and the electrode, for example, a laminated structure of a reflective plate made of Al and a transparent electrode made of ITO may be used. good.

As the liquid crystal material of the liquid crystal layer 5, Ne (refractive index for extraordinary light) = 1.5546, No (refractive index for normal light) = 1.4773, ΔN (Ne-No) = 0.
A liquid crystal material having a refractive index anisotropy of 0773 was used.

A λ / 4 plate 7 is arranged on the surface of the substrate 2 opposite to the side on which the counter electrode 4 is formed, and the delay axis of the λ / 4 plate 7 is
The liquid crystal layer 5 is arranged so as to be inclined by 45 ° with respect to the long axis direction of the liquid crystal molecules when a voltage is applied.

The λ / 4 plate 7 converts linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light.

The λ / 4 plate 7 was formed on the surface of the substrate 2 opposite to the side on which the counter electrode 4 was formed.
It may be provided between.

Further, the λ / 4 plate 7 can be attached to the surface of the substrate or integrated with the polarizing plate 6 to reduce the manufacturing cost.

Next, a polarizing plate 6 is provided on the surface of the λ / 4 plate 7 opposite to the substrate 2, and the transmission axis of the polarizing plate 6 is set to the λ / 4 plate 7.
It is arranged so as to be inclined at 45 ° with respect to the delay axis.

FIG. 7A is a plan view of the active matrix substrate of the first embodiment, and FIG. 7B is a sectional view taken along line FF of FIG. 7A.

This active matrix substrate includes a gate wiring 21, a data wiring 22, a driving element 23, a drain electrode 24, an auxiliary capacitance electrode 25, a gate insulating film 26, an insulating substrate 27, a contact hole 28, an interlayer insulating film 29, and reflection. The electrode 30 is provided.

The auxiliary capacitance electrode 25 is electrically connected to the drain electrode 24 and overlaps with the auxiliary capacitance line 32 via the gate insulating film 26 to form an auxiliary capacitance.

The contact hole 28 is provided in the interlayer insulating film 29 for connecting the reflection 30 and the auxiliary capacitance electrode 25.

A light transmission state in the liquid crystal display device of the first embodiment will be described with reference to FIG.

FIG. 13A shows a case of black display in which no voltage is applied to the liquid crystal layer, and FIG. 13B shows a case of white display in which a voltage is applied to the liquid crystal layer. The reflective electrode 3 is formed in the left region.

Black display will be described with reference to FIG.

The incident light that has entered from the surface of the polarizing plate 6 from the upper side of FIG. 13 (a) becomes linearly polarized light that matches the transmission axis of the polarizing plate after passing through the polarizing plate 6, and is incident on the λ / 4 plate 7. .

The λ / 4 plate 7 has a transmission axis direction of the polarizing plate 6 and λ / 4.
The / 4 plate 7 is arranged so that the delay axis direction is 45 °, and the light passing through the λ / 4 plate 7 is circularly polarized.

When no electric field is applied to the liquid crystal layer 5,
In the liquid crystal layer 5 made of a liquid crystal material exhibiting negative dielectric anisotropy, liquid crystal molecules are aligned almost vertically from the substrate surface, and the refractive index anisotropy of the liquid crystal layer 5 with respect to incident light is extremely small. ,
The phase difference caused by the light passing through the liquid crystal layer 5 is almost zero.

Therefore, the circularly polarized light that has passed through the λ / 4 plate 7 passes through the liquid crystal layer 5 without breaking the circularly polarized light, and the one substrate 1
It is reflected by the reflective electrode 3 above.

The reflected circularly polarized light passes through the liquid crystal layer 5 in the direction of the substrate 2 and is incident on the λ / 4 plate 7 again as circularly polarized light.

The circularly polarized light incident on the λ / 4 plate 7 becomes linearly polarized light in a direction orthogonal to the transmission axis direction of the polarizing plate 6 after passing through the λ / 4 plate 7, and is incident on the polarizing plate 6. .

The linearly polarized light that has passed through the λ / 4 plate 7 is linearly polarized light in the direction orthogonal to the transmission axis of the polarizing plate 6,
Is absorbed by and does not penetrate.

As described above, when no voltage is applied to the liquid crystal layer 5, black is displayed.

Next, white display will be described with reference to FIG.

FIG. 3B shows a case where a voltage is applied to the liquid crystal layer 5, which is the same as FIG. 3A until it passes through the λ / 4 plate 7, and the description thereof will be omitted.

When a voltage is applied to the liquid crystal layer 5, the liquid crystal molecules aligned vertically from the substrate surface are tilted horizontally to the substrate surface, and the circularly polarized light from the λ / 4 plate 7 incident on the liquid crystal layer 5 is
Due to the birefringence of liquid crystal molecules, it becomes elliptically polarized light, and after being reflected by the reflective electrode 3, the polarized light changes in the liquid crystal layer 5, and even after passing through the λ / 4 plate 7, linearly polarized light orthogonal to the transmission axis of the polarizing plate 6. However, light is transmitted through the polarizing plate 6.

By adjusting the voltage applied to the liquid crystal layer at this time, the amount of light that can be transmitted through the polarizing plate 6 after being reflected can be adjusted, and gradation display is possible.

Further, when a voltage is applied from the reflective electrode 3 and the counter electrode 4 to the liquid crystal layer 5 to change the alignment state of the liquid crystal molecules so that the phase difference of the liquid crystal layer 5 becomes a quarter wavelength condition, λ /
The circularly polarized light after passing through the plate 4 becomes a linearly polarized light orthogonal to the transmission axis of the polarizing plate 6 when passing through the liquid crystal layer 5 and reaching the reflecting electrode 3, and then passes through the liquid crystal layer 5 again and becomes circularly polarized light. After that, the linearly polarized light passes through the λ / 4 plate 7 and is parallel to the transmission axis of the polarizing plate 6, and the reflected light transmitted through the polarizing plate 6 becomes maximum.

Therefore, when no voltage is applied to the liquid crystal layer 5, black display is obtained without birefringence in the liquid crystal layer 5, and when a voltage is applied to the liquid crystal layer 5, the light transmittance varies depending on the applied voltage. It enables gradation display.

In FIG. 4, in the liquid crystal display device of the first embodiment, the vertical direction of the reflection type liquid crystal display device when the cell gap of the liquid crystal layer is d = 3.56 μm and the phase difference of the liquid crystal layer is dΔN = 0.2752. The spectral reflectance characteristics at the time of vertical incident light reception are shown.

Here, in FIG. 4, the spectral reflection at the time of vertical incidence and vertical light reception with respect to the single reflector is assumed to be 100.

As shown in FIG. 4, in the dark display in which no voltage is applied to the liquid crystal layer 5 and the bright display when a voltage of 3.25 V is applied, a sufficient contrast ratio of 50 or more in the entire wavelength range of 400 nm to 700 nm. Is obtained.

When the voltage applied to the liquid crystal layer 5 is 3.25V, a reflectance of about 40% is obtained, which is almost the same as the transmittance of the polarizing plate 6 used, and the light utilization efficiency is high. Highly suitable for reflective liquid crystal display devices.

In FIG. 5, the cell gap of the liquid crystal layer is d = 4.5 μm and the phase difference of the liquid crystal layer is dΔN = in the first embodiment.
9 shows the spectral reflectance characteristics of the reflective liquid crystal display device at the time of vertical incidence and vertical light reception when 0.3479 is set.

Therefore, in the reflection type liquid crystal display device in which the cell gap of the liquid crystal exhibiting the spectral reflectance characteristic in FIG. 5 is d = 4.5 μm, the dark display in which no voltage is applied to the liquid crystal layer 5 and the voltage of 3 V are applied. In the bright display of 400 nm to 700
A sufficient contrast ratio of 50 or more can be obtained over the entire wavelength range of nm.

When the voltage applied to the liquid crystal layer 5 is 3V, a reflectance of about 40% can be obtained as in the case of the reflection type liquid crystal display device having the cell gap d = 3.56 μm.

FIG. 6 shows the relationship between the cell gap at a wavelength of 550 nm and the contrast ratio when the reflective liquid crystal display device of Embodiment 1 is vertically incident and vertically received.

In FIG. 6, the measurement is performed by applying a voltage whose phase difference dΔn of the liquid crystal satisfies the quarter wavelength condition.

As shown in FIG. 6, in the reflective display device of Embodiment 1, the contrast ratio of 500 or more is maintained regardless of the cell gap of the liquid crystal layer.

Therefore, when a voltage is applied to the liquid crystal layer 5, it is possible to display without lowering the contrast ratio as long as the phase difference dΔn satisfies the ¼ wavelength condition, and it is possible to set the cell gap d arbitrarily. .

In FIG. 12, the delay axis of the λ / 4 plate 7 is shown by the polarizing plate 6
Λ / when tilted at 45 ° to the transmission axis of
4 shows the relationship between the deviation of the delay axis of the four plates 7 and the contrast ratio.

Here, if the angle deviation of the delay axis of the λ / 4 plate 7 is within 3 °, a contrast ratio of 50 or more is obtained,
A reflective liquid crystal display device having excellent display characteristics can be manufactured.

Therefore, in laminating the polarizing plate and the λ / 4 plate, a display device having high contrast can be obtained even if the angle between the delay axis of the λ / 4 plate 7 and the transmission axis of the polarizing plate 6 is slightly deviated from the set value.

Although the influence of the surface reflection of the panel is removed in FIGS. 6 and 7, the influence of the surface reflection of the panel cannot be ignored in actual use, and the contrast ratio in that case is 20. Although it is about the level, it is a good value as the contrast of the reflection type liquid crystal display device.

In the liquid crystal display device using the vertically aligned liquid crystal material used in this embodiment, the retardation of the liquid crystal layer can be made almost zero when no voltage is applied. Therefore, in the case of normally black display, the dark state is made darker. It is possible to increase the contrast.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG.

The same components as those in the first embodiment are designated by the same reference numerals.

On one of the substrates 1, a reflective electrode 3 made of a material having a high reflectance such as Al and Ta and a transparent electrode 8 made of a material having a high transmittance such as ITO are provided, and it faces the substrate 2. An electrode 4 is provided, and a liquid crystal layer 5 made of a liquid crystal material having a negative dielectric anisotropy is sandwiched between the reflective electrode 3 and the transparent electrode 8 and the counter electrode 4.

Alignment films (not shown) having vertical alignment properties are formed on the surfaces of the reflective electrode 3, the transparent electrode 8 and the counter electrode 4 which are in contact with the liquid crystal layer 5, and at least one of them is applied after the alignment film is applied. The alignment film is subjected to an alignment treatment such as rubbing.

The liquid crystal molecules of the liquid crystal layer 5 have a tilt angle of about 0.1 ° to 5 ° with respect to the vertical direction of the substrate surface by an alignment treatment such as rubbing on a vertical alignment film.

Here, although the reflective electrode 3 is used as an electrode for applying a voltage to the liquid crystal layer, the transparent electrode 8 is extended above the reflective electrode without using the reflective electrode as an electrode, and the liquid crystal layer in the reflective region is used. It may be an electrode for applying a voltage to 5.

As the liquid crystal material of the liquid crystal layer 5, the liquid crystal material having the same refractive index anisotropy of Ne = 1.5546 and No = 1.4773 as in Embodiment 1 was used.

A λ / 4 plate 7 is arranged on the surface of the substrate 2 opposite to the side where the counter electrode 4 is formed, and the delay axis of the λ / 4 plate 7 is defined by the liquid crystal molecules when the voltage is applied to the liquid crystal layer 5. It is arranged so as to be inclined at 45 ° with respect to the major axis direction.

A λ / 4 plate 10 is arranged on the surface of the substrate 1 opposite to the side where the reflective electrode 3 and the transparent electrode 8 are formed, and the delay axis of the λ / 4 plate 10 is the same as the delay axis of the λ / 4 plate 7. It is set in the same direction.

A polarizing plate 6 is provided on the surface of the λ / 4 plate 7 opposite to the substrate 2, and a polarizing plate 9 is provided on the surface of the λ / 4 plate 10 opposite to the substrate 1, respectively. The transmission axis of the polarizing plate 9 is set to be inclined by 45 ° with respect to the delay axes of the λ / 4 plate 7 and the λ / 4 plate 10.

FIG. 8A shows a plan view of an active matrix substrate of Embodiment 2 of the present invention, and FIG. 8B shows FIG.
The sectional view of the AA cross section of (a) is shown.

The active matrix substrate includes a gate wiring 21, a data wiring 22, a driving element 23 and a drain electrode 2.
4, an auxiliary capacitance electrode 25, a gate insulating film 26, an insulating substrate 27, a contact hole 28, an interlayer insulating film 29, a reflective pixel electrode 30 and a transmissive pixel electrode 31.

The auxiliary capacitance electrode 25 is electrically connected to the drain electrode 24 and overlaps the gate wiring 21 via the gate insulating film 26 to form an auxiliary capacitance.

The contact hole 28 is formed through the interlayer insulating film 2 in order to connect the transparent pixel electrode 31 and the auxiliary capacitance electrode 25.
9 is provided.

This active matrix substrate is provided with a reflective picture element electrode 30 and a transmissive picture element electrode 31 in one picture element, and a reflective picture element that reflects light from the outside is reflected in one picture element. An elementary electrode 30 portion and a transmitting picture element electrode 31 portion that transmits the light of the backlight are formed.

A light transmission state in the liquid crystal display device of the second embodiment will be described with reference to FIG.

FIG. 13A shows a case of black display in which no voltage is applied to the liquid crystal layer 5, and FIG. 13B shows a case of white display in which a voltage is applied to the liquid crystal layer 5.

In FIG. 13, the region having the reflective electrode 3 has the same structure as the reflective liquid crystal display device of the first embodiment, and when used as a reflective display device, the same principle as that of the first reflective liquid crystal display device is used. The description is omitted because it can be displayed with.

The state of light in the region where the transparent electrode 8 is formed, which is the right region of FIGS. 13A and 13B, will be described.

A light source (not shown) from the lower side of FIG.
The light emitted by means of the polarizing plate 9 becomes a linearly polarized light which coincides with the transmission axis of the polarizing plate 9.

The λ / 4 plate 10 includes the λ / 4 plate 10 and the polarizing plate 9
The light is passed through the λ / 4 plate 10 to be circularly polarized light.

When no electric field is generated in the liquid crystal layer 5,
In the liquid crystal layer 5 made of a liquid crystal material exhibiting negative dielectric anisotropy, liquid crystal molecules are aligned almost vertically from the substrate surface, and the refractive index anisotropy of the liquid crystal layer 5 with respect to incident light is extremely small. ,
The phase difference caused by the light passing through the liquid crystal layer 5 is almost zero.

Therefore, the circularly polarized light emitted from the λ / 4 plate 10 passes through the liquid crystal layer 5 without breaking the circularly polarized light, and the λ / 4 plate 7
Incident on.

The delay axis direction of the λ / 4 plate 10 and the delay axis direction of the λ / 4 plate 7 coincide with each other, and the circularly polarized light incident on the λ / 4 plate 7 is orthogonal to the transmission axis direction of the polarizing plate 9. The light becomes linearly polarized light in the direction and enters the polarizing plate 6.

The linearly polarized light emitted from the λ / 4 plate 7 is linearly polarized light in the direction orthogonal to the transmission axis of the polarizing plate 6, and is absorbed by the polarizing plate 6 and does not transmit light.

As described above, when no voltage is applied to the liquid crystal layer 5, black is displayed.

Next, white display will be described with reference to FIG.

FIG. 13B shows a case in which a voltage is applied to the liquid crystal layer, and FIG.
Since it is the same as (a), the description is omitted.

When a voltage is applied to the liquid crystal layer 5, the liquid crystal molecules of the liquid crystal layer 5 which are oriented in the vertical direction from the substrate surface are tilted in the horizontal direction with respect to the substrate surface, and the circularly polarized light from the λ / 4 plate 10 incident on the liquid crystal layer. Becomes elliptically polarized light due to the birefringence of the liquid crystal layer 5,
Even after passing through the / 4 plate 7, the light does not become linearly polarized light orthogonal to the transmission axis of the polarizing plate 6, and the light passes through the polarizing plate 6.

By adjusting the voltage applied to the liquid crystal layer 5 at this time, the polarization state of the light incident on the polarizing plate 6 can be changed, and the amount of light passing through the polarizing plate 6 can be adjusted to display gradation. It will be possible.

When a voltage is applied to the liquid crystal layer 5 so that the phase difference of the liquid crystal layer 5 becomes a half wavelength condition, circularly polarized light after passing through the λ / 4 plate 10 has a cell thickness of the liquid crystal layer 5. It becomes a linearly polarized light which is orthogonal to the transmission axis of the polarizing plate 9 at a half point thereof, and becomes a circularly polarized light when passing through the remaining liquid crystal layer 5.

Circularly polarized light emitted from the liquid crystal layer 5 becomes linearly polarized light parallel to the transmission axis of the polarizing plate 6 when passing through the λ / 4 plate 7, so that most of the light incident on the polarizing plate 6 is formed.
Therefore, the transmitted light of the polarizing plate 6 becomes maximum.

Therefore, in the second embodiment, in both the reflective electrode 3 region and the transparent electrode 8 region, when no voltage is applied to the liquid crystal layer 5, there is no birefringence in the liquid crystal layer 5 and a black display is obtained. By applying a voltage to the liquid crystal layer 5, it is possible to adjust the amount of light transmission and perform gradation display.

FIG. 9 shows the liquid crystal layer cell gap d = 3.56 μm and the liquid crystal layer phase difference dΔN = in the second embodiment.
9 shows the spectral transmittance characteristics of the 0.2752 transmissive / reflective liquid crystal display device in the transmissive region at the time of vertical incidence and vertical light reception.

Here, the spectral reflectance characteristic in the region where the reflective electrode 3 is present is the same as in FIG.

In FIG. 9, the spectral transmission when vertically incident on the air and at the time of vertical light reception is 100.

As shown in FIG. 9, in black display in which no voltage is applied to the liquid crystal layer 5 and in bright display when a voltage of 5 V is applied,
A sufficient contrast ratio can be obtained in the entire wavelength range of 400 nm to 700 nm.

When the voltage applied to the liquid crystal layer 5 is 5 V, a reflectance of about 30% is obtained, which is about 80% of the transmittance of the polarizing plate 6 used.

From this fact, this display system has a high light utilization efficiency and is suitable for a transflective liquid crystal display device.

FIG. 10 shows a transflective liquid crystal display in which the cell gap of the liquid crystal layer 5 is d = 4.5 μm and the phase difference of the liquid crystal layer 5 is dΔN = 0.3479 in the liquid crystal display device of the second embodiment. 7 shows the spectral transmittance characteristics of the device in the transmission region when vertically incident and vertically received.

Similar to the transflective liquid crystal display device having the cell gap d = 3.56 μm in FIG. 9, from 400 nm in black display in which no voltage is applied to the liquid crystal layer 5 and in bright display when a voltage of 5 V is applied. A sufficient contrast ratio is obtained over the entire wavelength range of 700 nm, and a transmittance of about 40% is obtained when the voltage applied to the liquid crystal layer is 5V.

FIG. 11 shows a wavelength 55 at the time of vertical incidence and vertical light reception in the transmissive region of the transflective liquid crystal display device of the second embodiment.
The relationship between the cell gap at 0 nm and the contrast ratio is shown.

In FIG. 11, the measurement is performed by applying a voltage in which the phase difference dΔn of the liquid crystal satisfies the 1/2 wavelength condition.

Thus, regardless of the cell gap, a contrast ratio of 800 or more is used in the area of the transparent electrode 8 as a transmissive liquid crystal display device, and a contrast ratio of 500 or more is used in the area of the reflective electrode 3 as a reflective liquid crystal display device. I am maintaining.

Therefore, when a voltage is applied to the liquid crystal layer 5, the phase difference d
As long as Δn satisfies the 1/2 wavelength condition, it is possible to display without lowering the contrast ratio, and it is possible to arbitrarily set the cell gap d.

FIG. 12 shows the difference between the angle of the delay axis of the λ / 4 plate 7 and the contrast ratio when the delay axis of the λ / 4 plate 7 is inclined by 45 ° with respect to the transmission axis of the polarizing plate 6 as 0 °. Show the relationship.

Here, if the angle deviation of the delay axis of the λ / 4 plate 7 is within 3 °, it is used as a transmissive liquid crystal display device in the transmissive area in which the transparent electrode 8 is formed, or the reflective electrode 3 is used.
When used as a reflection type liquid crystal display device in the reflection area formed with, a contrast ratio of 50 or more can be obtained, and a reflection type transmission type dual use type liquid crystal display device having good display characteristics can be obtained.

Therefore, when the ambient light is dark, it is used as a transmissive liquid crystal display device which displays by utilizing the light transmitted through the transparent electrode 8 using a backlight, and when the ambient light is bright, the light reflectance is increased. It is possible to display as a reflection type liquid crystal display device that displays by utilizing the light reflected by the reflection electrode 3 formed of a relatively high film.

Therefore, when the ambient light is dark on one panel, the backlight is used, and when the ambient light is bright, the ambient light is used without using the backlight, or both the backlight and the reflected light are used. It can be used as a transflective liquid crystal display device capable of displaying even when used.

Therefore, when the ambient light is brighter than the conventional transmissive liquid crystal display device, the power consumption is low because the backlight is not used, and when the ambient light is dark, the backlight is used, and thus the conventional reflection can be achieved. It is possible to overcome the drawback that a sufficient display cannot be obtained when the ambient light is dark as in the case of a liquid crystal display device.

The liquid crystal display device using the vertically aligned liquid crystal material used in this embodiment can make the retardation of the liquid crystal layer almost zero when no voltage is applied. Therefore, in the normally black display, the transmission display and the reflection display can be performed. The dark state can be made darker and the contrast can be increased.

(Embodiment 3) Embodiment 3 of the present invention will be described with reference to the schematic sectional view of FIG.

The description of the configuration common to the first and second embodiments will be omitted.

The liquid crystal display device of Embodiment 3 has the λ / 4 plate 10 and the optical compensation plate 12 between the substrate 1 and the polarizing plate 9, and the λ / 4 plate 7 between the substrate 2 and the polarizing plate 6. It has an optical compensation plate 11.

When no voltage is applied to the liquid crystal layer 5, the liquid crystal layer 5 made of a liquid crystal material exhibiting negative dielectric anisotropy is used.
The liquid crystal molecules are aligned almost vertically from the substrate surface, and there is no refractive index anisotropy due to the liquid crystal layer 5 from the front surface of the substrate.

However, when used as a reflection type liquid crystal display device, light is used not only in the direction perpendicular to the substrate surface but also in light from other directions. When the light in the oblique direction enters the liquid crystal layer 5, it is affected by the refractive index anisotropy.

Further, since the viewing angle direction is not always perpendicular to the substrate surface, as the viewing angle direction deviates from the direction perpendicular to the substrate surface, the anisotropy of the refractive index of the liquid crystal molecules of the liquid crystal layer 5 affects the contrast. Occurs.

Therefore, the liquid crystal layer 5 is provided with the optical compensation layers 11 and 12 for compensating the influence of the refractive index anisotropy of the liquid crystal molecules generated in the light incident direction and the viewing angle direction. It is possible to compensate the refractive index anisotropy that occurs in the light incident direction or the viewing angle direction, and prevent the contrast from decreasing depending on the light incident direction or the viewing angle direction.

In the vertical alignment liquid crystal layer 5, when the pretilt of the liquid crystal molecules is laid out from the direction perpendicular to the substrate surface so that the liquid crystal molecules tilt in one direction when a voltage is applied, no voltage is applied to the vertical alignment liquid crystal layer 5. Even when added, some refractive index anisotropy occurs in the direction perpendicular to the substrate. Therefore, by designing the optical compensation layer so as to compensate for this refractive index anisotropy, the vertical The contrast ratio seen from the direction is further improved.

In the third embodiment, the λ / 4 plate and the optical compensation layer are described as separate layers, but the same effect can be obtained by incorporating them in the same layer.

Further, although two optical compensation layers, that is, the optical compensation layer 11 and the optical compensation layer 12 are used in the third embodiment, the optical compensation layer 11 may be used alone.

Although the transmissive / reflective display device has been described in the third embodiment, in the reflective liquid crystal display device of the first embodiment, the refractive index of the liquid crystal molecules of the liquid crystal layer 5 is anisotropic between the polarizing plate 6 and the reflective electrode 3. By providing the optical compensation layer so as to compensate the property, it is possible to prevent the contrast ratio from being lowered.

Further, in the first to third embodiments, the case of white display and black display has been described, but color display can be performed by providing color filters of respective colors at corresponding positions of the reflection area and the transmission area.

By adding a chiral material to the vertically aligned liquid crystal layer 5 using the liquid crystal material exhibiting the negative dielectric anisotropy of the first to third embodiments, the liquid crystal molecules are swirled when the voltage is applied and the voltage is applied. It is possible to stabilize the swirling of the liquid crystal molecules at that time.

At that time, when the liquid crystal layer is oriented so as to have a 90 ° twist, the liquid crystal layer is oriented at an angle of several degrees with respect to the normal direction of the substrate surface to prevent disclination when a voltage is applied. Retardation occurs in the tilt direction of the liquid crystal molecules, but since the tilt directions of the liquid crystal molecules near the substrate form an angle of 90 ° with each other near the upper and lower substrates, it is possible to cancel the generated retardation, A black display with little leakage light can be obtained.

Although the first to third embodiments use the vertically aligned liquid crystal having a negative dielectric anisotropy, the same display can be performed by using the parallel aligned liquid crystal.

That is, when the parallel alignment liquid crystal is used instead of the vertical alignment liquid crystal, the liquid crystal molecules are arranged parallel to the substrate surface when no voltage is applied, and the liquid crystal molecules are inclined in the direction normal to the substrate surface when a voltage is applied. It is possible to obtain a liquid crystal display device that displays white when no voltage is applied and displays black when voltage is applied.

In the case of black display using this parallel alignment liquid crystal, liquid crystal molecules near the substrate cause more retardation to remain than in the case of vertical alignment liquid crystal. Therefore, in order to perform more complete black display, a retardation plate that compensates for this may be used together.

In the liquid crystal layer in which the liquid crystal molecules are oriented substantially in the direction perpendicular to the substrate surface, when the retardation of α remains in the reflection mode, instead of the λ / 4 plate 7,
A retardation plate having a retardation of (λ / 4−α) may be arranged.

In the reflection mode, elliptically polarized light deviated from the circularly polarized light by the retardation remaining in the liquid crystal layer is incident on the liquid crystal layer. The light passes through the liquid crystal layer and becomes circularly polarized light in a region having a reflection function, and is reflected to become circularly polarized light with its rotation direction reversed. When the light passes through the liquid crystal layer and exits from the liquid crystal layer, it becomes elliptically polarized light deviated from circularly polarized light. The elliptically polarized light at this time is
At the time of incidence, the phase is shifted by 90 degrees. When it passes through the retardation plate, it becomes linearly polarized light which is orthogonal to the transmission axis of the polarizing plate 6.

Therefore, even if the retardation remaining in the liquid crystal layer in the state where the liquid crystal molecules are oriented in the direction perpendicular to the substrate surface cannot be ignored, the retardation plate is arranged in consideration of the retardation to provide contrast in the reflection mode. High display can be realized.

Further, when the retardation of α in the reflective mode and β in the transmissive mode remains in the liquid crystal layer, λ
In place of the / 4 plate 7, a retardation plate having a retardation of (λ / 4-α), and in place of the λ / 4 plate 10 (λ / 4- (β-
A retardation plate having a retardation of α)) may be arranged.

In the transmissive mode in which the transmitted light in the region having the transmissive function is used for display, when the liquid crystal molecules are oriented in the direction perpendicular to the substrate surface, an ellipse in the same state as the emitted light in the reflective mode when emitted from the liquid crystal layer. The above (λ / 4-
A retardation plate having a retardation of (β−α) is set, and the elliptically polarized light having the retardation is (λ / 4−).
Since the light enters the retardation plate having the retardation of α), when it passes through the retardation plate having the retardation of (λ / 4-α), it becomes a linearly polarized light orthogonal to the transmission axis of the polarizing plate 6 and leaks light. There is little dark display.

Therefore, even if the retardation remaining in the liquid crystal layer in the state where the liquid crystal molecules are oriented in the direction perpendicular to the substrate surface cannot be ignored, the contrast in the reflection mode can be reduced by disposing the retardation plate in consideration of the retardation. High display can be realized.

[0153]

The liquid crystal display device having the region having the reflection function and the region having the transmission function has the first polarization means and the second polarization means.
By having the polarizing means, the first retardation plate, and the second retardation plate, high-contrast display can be performed in a display device having a reflection mode and a transmission mode.
Further, when the reflection mode and the transmission mode are used together, dark display can be performed at the same time, and even when both are used together, high contrast display is possible. Further, gradation display is possible by changing the retardation value by the voltage.

Since the retardations of the first retardation plate and the second retardation plate are set to the λ / 4 condition, the liquid crystal molecules of the liquid crystal layer are oriented substantially in the direction perpendicular to the substrate surface. When the liquid crystal layer has almost no retardation, the light that passes through the liquid crystal layer and the retardation plate and is incident on the first polarizing plate is orthogonal to the transmission axis of the polarizing plate in the reflective region and the transmissive region. Since it becomes linearly polarized light, dark display with little light leakage can be obtained.

Further, when the retardation of the liquid crystal layer in the reflective region remains by α, the retardation of the first retardation plate is set to the condition of (λ / 4−α). When the molecules are oriented almost in the direction perpendicular to the substrate surface, the retardation of the liquid crystal layer in the reflective region is α
Even though only the light remains, in the reflection area, the light that passes through the liquid crystal layer and the retardation plate and enters the first polarizing plate becomes linearly polarized light that is orthogonal to the transmission axis of the polarizing plate, so that there is little light leakage. Display is obtained.

When the retardation of the liquid crystal layer in the reflective region remains by α and the retardation of the liquid crystal layer in the transmissive region remains by β, the retardation of the first retardation plate is (λ / 4−4 In (α) condition, the retardation of the second retardation plate is set to (λ / 4- (β-α)) condition, so that the liquid crystal molecules of the liquid crystal layer are oriented substantially in the direction perpendicular to the substrate surface. When the retardation of the liquid crystal layer in the reflective region is α, and the retardation of the liquid crystal layer in the transmissive region is β, the reflective region and the transmissive region pass through the liquid crystal layer and the retardation plate. Since the light incident on the first polarizing plate is linearly polarized light orthogonal to the transmission axis of the polarizing plate, dark display with less light leakage can be obtained.

The first retardation plate and the second retardation plate are λ / 4 plates, and the angle formed by the transmission axis of the first polarizing means and the first retardation plate is 45 °. Since the angle formed by the transmission axis of the second polarizing means and the second retardation plate is 45 °, the state of the liquid crystal molecules at the time of dark display is the same even when the reflection mode and the transmission mode are used together. Dark display without light leakage is possible, and a high-contrast display is realized as a reflective type, a transmissive type, or a dual-purpose type regardless of the ambient light intensity.

When a vertically aligned liquid crystal layer made of a liquid crystal material exhibiting negative dielectric constant anisotropy is used, less light leaks from the polarizing plate during black display when no voltage is applied, and white light when voltage is applied. It is possible to realize a reflection type liquid crystal display device which has high light utilization efficiency in display and color display by a color filter and has excellent display quality.

Further, by providing an optical compensation layer for compensating the influence of the refractive index anisotropy of the liquid crystal molecules generated in the light incident direction or the viewing angle direction of the liquid crystal layer, the light incident direction or the viewing angle direction is provided. It is possible to prevent a decrease in contrast depending on

If a chiral material is added to a vertically aligned liquid crystal layer made of a liquid crystal material exhibiting negative dielectric anisotropy and the liquid crystal molecules are swung when a voltage is applied, the swirling of the liquid crystal molecules when a voltage is applied is stabilized. When the rubbing directions of the upper and lower substrates are not in the same direction, the traces of the alignment treatment are not in the same direction, so that the streaks are less noticeable.

If the liquid crystal layer is twisted by 90 °, it is retarded in the tilt direction of the liquid crystal molecules when the liquid crystal layer is aligned at an angle of several degrees with respect to the normal direction of the substrate in order to prevent disclination when a voltage is applied. However, since the liquid crystal molecules in the vicinity of the substrate are inclined by 90 ° with respect to each other in the vicinity of the upper and lower substrates, it is possible to cancel the generated retardation and obtain a black display with less leakage light. To be

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a reflective liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram of a transflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional configuration diagram of a transflective liquid crystal display device according to Embodiment 3 of the present invention.

FIG. 4 is a spectral reflectance characteristic diagram of the reflective liquid crystal display device according to the first embodiment of the present invention at the time of vertical incidence vertical light reception with a cell gap d = 3.56 μm.

FIG. 5 is a spectral reflectance characteristic diagram of the reflective liquid crystal display device according to the first embodiment of the present invention at the time of vertical incidence and vertical light reception with a cell gap d = 4.5 μm.

FIG. 6 is a relationship diagram of a cell gap and a contrast ratio at a wavelength of 550 nm at the time of vertical incidence and vertical light reception of the reflective liquid crystal display device according to the first exemplary embodiment of the present invention.

FIG. 7 is a diagram showing an electrode configuration of the reflective liquid crystal display device according to the first embodiment of the present invention.

FIG. 8 is a diagram showing an electrode configuration of a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 9 is a cell gap d = in the second embodiment of the present invention.
It is a spectral reflectance characteristic figure at the time of vertical incidence vertical light reception in the transmissive area | region of a transmission / reflection dual type liquid crystal display device of 3.56 μm.

FIG. 10 is a cell gap d according to the second embodiment of the present invention.
FIG. 6 is a spectral reflectance characteristic diagram of a transmissive / reflective liquid crystal display device of = 4.5 μm when vertically incident and vertically received.

FIG. 11 is a relationship diagram of a cell gap and a contrast ratio at a wavelength of 550 nm at the time of vertical incidence and vertical light reception in the transmissive region of the transflective liquid crystal display device according to the second embodiment of the present invention.

FIG. 12 shows a case where the delay axis of the λ / 4 plate in the transmission region of the transflective liquid crystal display device according to the second embodiment of the present invention is inclined by 45 ° with respect to the transmission axis of the polarizing plate, and is set to 0 °.
FIG. 6 is a relationship diagram of a shift in angle of a delay axis of a λ / 4 plate and a contrast ratio.

FIG. 13 is a diagram illustrating a light transmission state in the liquid crystal display device according to the first and second embodiments of the present invention.

[Explanation of symbols]

1, 2 substrate 3 Reflective electrode 4 Counter electrode 5 Liquid crystal layer (vertical alignment) 6, 9 Polarizer 7, 10 λ / 4 plate 8 transparent electrodes 11, 12 Optical compensation layer

Continued front page    (72) Inventor Shogo Fujioka             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Yuko Maruyama             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Naoyuki Shimada             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Yoji Yoshimura             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Mikio Katayama             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company (72) Inventor Yu Ishii             22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka             Inside the company F-term (reference) 2H049 BA02 BA06 BA42 BB03 BC22                 2H091 FA11 FA12 FA14Y FA41Z                       FC10 FC26 FC29 FC30 FD04                       FD10 FD12 FD22 FD23 LA03                       LA11 LA12 LA13 LA18

Claims (2)

[Claims] 1. A first substrate having a region having a reflection function and a region having a transmission function, and the other substrate having a counter electrode formed thereon, wherein a liquid crystal layer is sandwiched between the one substrate and the other substrate. A liquid crystal display device, comprising: a first polarization means provided on a surface of the other substrate opposite to the liquid crystal layer; and a second polarization means provided on a surface of the one substrate opposite to the liquid crystal layer. Means, a first retardation plate provided between the first polarizing means and the liquid crystal layer, and a second phase difference provided between the second polarizing means and the liquid crystal layer. A plate, the first retardation plate and the second retardation plate are λ / 4 plates, and the transmission axis of the first polarizing means and the delay axis of the first retardation plate are included. Is 45 °, and the angle between the transmission axis of the second polarization means and the delay axis of the second retardation plate is A liquid crystal display device having a degree of 45 °. 2. A one substrate having a region having a reflection function and a region having a transmission function, and the other substrate having a counter electrode formed thereon, wherein a liquid crystal layer is sandwiched between the one substrate and the other substrate. A liquid crystal display device, comprising: a first polarization means provided on a surface of the other substrate opposite to the liquid crystal layer; and a second polarization means provided on a surface of the one substrate opposite to the liquid crystal layer. Means, a first retardation plate provided between the first polarizing means and the liquid crystal layer, and a second retardation plate provided between the second polarizing means and the liquid crystal layer. A liquid crystal display device having a plate, wherein the transmission axis of the first polarization unit and the transmission axis of the second polarization unit are set in the same direction.