JP2000235180A - Liquid crystal device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve contrast characteristics of transmission display by controlling the polarized state of light emitting from a liquid crystal layer to a first polarizing plate in a dark display state to be same both for reflection display and transmission display. SOLUTION: In a dark display state, the light entering the top face of a liquid crystal cell is transmitted through a liquid crystal layer and reflected by a semitransmitting reflection film 123 so that the light is changed into circularly polarized light or elliptically polarized light in a specified rotation direction. On the other hand, the light entering the back face of the liquid crystal cell is changed into light having a specified rotation direction of polarization by the optical device, namely, in the same rotation direction as that of the light entering the top face and reflected by the semitransmitting reflection film 123, and is transmitted through the semitransmitting reflection film 123. Namely, the polarized state of the light emitted from the liquid crystal layer to a first polarizing plate in a dark display state is same or almost same in both of reflection display and transmission display, and therefore, decrease in contrast in transmission display due to the difference in the polarized state between two kinds of display can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device, in particular, to a reflection type display function of displaying light by entering a liquid crystal layer from a front side by a semi-transmissive reflection layer, and a function of reflecting light entering the liquid crystal layer from a back side. The present invention relates to a transflective liquid crystal device capable of both a transmissive display function of transmitting a transflective layer for display. Further, the present invention relates to an electronic device using the liquid crystal device.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal device has been used for a display portion of a portable electronic device. However, since a display is performed using external light incident on a liquid crystal layer from the surface of a liquid crystal cell, it is used in a dark place. There is a problem that the display cannot be recognized. Therefore, a semi-transmissive reflective liquid crystal device has been devised which uses external light in a bright place as in the case of a reflective liquid crystal device, and enables a display to be recognized by light emitted from a lighting device arranged on the back side of the liquid crystal cell in a dark place. Have been.

This transflective liquid crystal device is disclosed in
As described in JP-A-49271, a polarizing plate, a transflective plate, and a lighting device are sequentially arranged on the back surface side of a liquid crystal cell. In this liquid crystal device, when the surroundings are bright, reflection display is performed by reflecting external light incident on the liquid crystal layer from the liquid crystal cell surface with a semi-transmissive reflector, and when the surroundings are dark, light is emitted from the lighting device. The transmissive display is performed by transmitting the light through the transflective plate.

Examples of other transflective liquid crystal devices include:
There is a transflective liquid crystal device described in Japanese Patent Application Laid-Open No. 8-292413 for the purpose of improving the brightness of a reflective display. This transflective liquid crystal device has a configuration in which a transflective plate, a retardation plate, a polarizing plate, and a backlight are arranged in this order on the back side of a liquid crystal cell. The reflective display is performed by reflecting the external light incident on the LCD with a semi-transmissive reflective plate. When the surroundings are dark, the light emitted from the backlight is transmitted through the semi-transmissive reflective plate to perform the transmissive display. With such a configuration, since there is no polarizing plate between the liquid crystal cell and the transflective plate, a reflective display brighter than the liquid crystal device described above can be obtained.

However, in the transflective liquid crystal device described in the above publication, since a transparent substrate is interposed between the liquid crystal layer and the transflective plate, a double image due to parallax is generated during reflective display. . In particular, in a color liquid crystal device in which a transflective liquid crystal device and a color filter described in the above publication are combined, a color filter through which light incident on the liquid crystal layer from the liquid crystal cell surface side passes, and the light is transmitted by a transflective plate. There is a high possibility that the color filter is different from the color filter that transmits after being reflected, and the display color becomes lighter.

To solve this problem, Japanese Patent Laid-Open No. 7-31
According to 8929 and JP-A-7-333598,
A transflective liquid crystal device in which a transflective plate is disposed in a liquid crystal cell to eliminate parallax has been invented.

[0007]

SUMMARY OF THE INVENTION Incidentally, Japanese Patent Application Laid-Open No.
The transflective liquid crystal device described in JP-A-318929 and JP-A-7-333598, that is, a transflective liquid crystal device that performs reflective display without using a polarizing plate provided on the back side of a liquid crystal cell. When light incident from the surface side of the liquid crystal cell and passing through the liquid crystal layer is reflected by the semi-transmissive reflector, the light becomes circularly polarized light or elliptically polarized light having a high ellipticity in a dark display state, and becomes linearly polarized light or light in a bright display state. It is preferable that the elliptically polarized light has a low ellipticity. Because the circularly polarized light or the elliptically polarized light having a high ellipticity reflected by the semi-transmissive reflection plate passes through the liquid crystal layer again, linearly polarized light orthogonal to the transmission axis of the polarization plate provided on the liquid crystal cell surface side, Alternatively, the light becomes elliptically polarized light having a low ellipticity and is absorbed by the polarizing plate, so that good contrast characteristics are realized.

On the other hand, the light transmitted through the transflective plate from the back side of the liquid crystal cell is always the same polarization state regardless of the display state.

In the transflective liquid crystal device described in JP-A-7-318929 and JP-A-7-333598, a liquid crystal is placed between a polarizing plate provided on the back side of a liquid crystal cell and a transflective film. Since no optical element for changing the polarization of light incident on the layer is provided, linearly polarized light transmitted through the polarizing plate on the back side of the liquid crystal cell always enters the liquid crystal layer. Therefore, if the setting preferable for the reflective display, that is, the light reflected by the semi-transmissive reflector is circularly polarized light or elliptically polarized light having a high ellipticity in a dark display state, the contrast characteristics of the transmissive display deteriorate.

This is because linearly polarized light incident from the back side of the liquid crystal cell in the dark display state is converted into circularly polarized light or elliptically polarized light having a high ellipticity by passing through the liquid crystal layer. This is because the light passes through the polarizing plate provided on the cell surface side.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its first object to obtain a transflective liquid crystal device having good transmissive display contrast characteristics. It is a second object of the present invention to obtain a transflective liquid crystal device which does not cause any problem.

[0012]

In order to achieve the above object, the present invention provides a reflective display function of reflecting light incident on a liquid crystal layer from one side by a semi-transmissive reflective layer for display. A transmissive display function of transmitting and displaying light incident from the other side opposite to the side through the transflective layer, by changing the voltage applied to the liquid crystal layer,
A first display state, which is a bright display state, and a second display state, which is a dark display state, can be selected. In the second display state, light enters the liquid crystal layer from the one side. A liquid crystal device in which light passes through the liquid crystal layer and is reflected by a semi-transmissive reflective film to be circularly polarized light or elliptically polarized light in a predetermined rotation direction, and a first polarizing plate provided on the one side; An optical element provided on the other side to convert light incident on the transflective layer from the other side into polarized light in the predetermined rotation direction.

The semi-transmissive reflection layer in the first liquid crystal device is a layer that reflects and transmits incident light at a certain reflectance and transmittance, and is, for example, a commercially available half mirror, a metal film provided with an opening. And a metal film formed so as to be very thin so that a part of light can be transmitted.

In the mode of the first liquid crystal device, reflection type display is performed by using light incident from one side, that is, the liquid crystal cell surface side. In this case, a linear operation is performed by the polarizing action of the first polarizing plate. The polarized light enters the liquid crystal layer from the liquid crystal cell surface side, passes through the liquid crystal layer, is reflected by the transflective layer, and passes through the liquid crystal layer again. The light that has passed through the first polarizing plate is emitted from the liquid crystal device surface side as image light.

When the amount of light incident from the front side of the liquid crystal cell is small, for example, in a dark place, the liquid crystal device performs transmissive display using light incident from the other side, that is, the back side of the liquid crystal cell. In this case, the light from the other side passes through the transflective layer and then passes through the liquid crystal layer. Then, the light that has passed through the first polarizing plate is emitted from the liquid crystal device surface side as image light.

In the first liquid crystal device, in a dark display state, light incident from the surface of the liquid crystal cell passes through the liquid crystal layer and is reflected by the semi-transmissive reflection film, so that circularly polarized light in a predetermined rotation direction is obtained. Or it becomes elliptically polarized light. Then, by passing through the liquid crystal layer again, linear polarized light in a direction orthogonal to the transmission axis of the first polarizing plate or elliptically polarized light having a long axis direction different from the transmission axis of the first polarizing plate is obtained. Absorbed.

On the other hand, the light incident from the back side of the liquid crystal cell is
The light becomes the light in the predetermined rotation direction by the optical element, that is, the same rotation direction as the light from the liquid crystal cell surface side reflected by the transflective layer, and transmits through the transflective layer. Then, as the light passes through the liquid crystal layer, it becomes linearly polarized light in a direction orthogonal to the transmission axis of the first polarizing plate or elliptically polarized light whose major axis direction is different from the transmission axis of the first polarizing plate, and is absorbed by the first polarizing plate. You.

That is, in the dark display state, the polarization state of the light emitted from the liquid crystal layer toward the first polarizing plate coincides or approximates between the reflection type display and the transmission type display. Can be prevented from lowering the contrast of the transmissive display due to the difference in

In one embodiment of the first liquid crystal device according to the present invention, in the second display state, the ellipticity when light from the one side is reflected by the semi-transmissive reflection layer is determined. The ellipticity when light from the other side transmits through the semi-transmissive reflective layer substantially coincides with the ellipticity.

According to this aspect, the polarization state of the light emitted from the liquid crystal cell surface side coincides between the reflective display and the transmissive display in the dark display state, so that the contrast of the transmissive display is reduced. Can be prevented.

In another embodiment of the first liquid crystal device of the present invention, the voltage applied to the liquid crystal layer is changed so that the first display state is a bright display state and the second display state is a dark display state.
And a third display state which is intermediate in brightness between them. In the third display state, the liquid crystal layer is applied to the liquid crystal layer from one side. In this embodiment, the third display state does not indicate only a specific brightness, but depends on a voltage applied to the liquid crystal layer. Includes multiple possible display states.

According to this aspect, it is possible to select a bright display state, a dark display state, and a display state having an intermediate brightness, so that a so-called halftone display is possible.

In another aspect of the first liquid crystal device, in the second display state, light incident on the liquid crystal layer from the one side is reflected by the semi-transmissive reflection film so that predetermined light is reflected. And the light incident on the liquid crystal layer from the one side in the first display state is linearly polarized when reflected by the transflective layer.

According to this aspect, in the second display state, light from the surface of the liquid crystal cell is reflected by the semi-transmissive reflection film to become circularly polarized light. After being reflected by the transflective layer and passing through the liquid crystal layer again, the light becomes linearly polarized light orthogonal to the transmission axis of the first polarizer and is absorbed by the first polarizer almost 100%. On the other hand, in the first display state, light incident on the liquid crystal layer from the liquid crystal cell surface side is reflected by the semi-transmissive reflection film without changing the polarization state, passes through the liquid crystal layer again, and Transmit through the polarizing plate. Therefore, a reflective display with the best light use efficiency and contrast characteristics is realized. In this case, if the light from the rear surface side of the liquid crystal cell is transmitted through the semi-transmissive reflective layer as circularly polarized light, the contrast in the transmissive display becomes maximum.

In another aspect of the first liquid crystal device, the optical element includes a second polarizer or a reflective polarizer provided on the other side, the second polarizer or the reflective polarizer, and the liquid crystal cell. And a retardation plate provided between them.
As the second polarizing plate used in this embodiment, a polarizing plate having a function of transmitting light of a linearly polarized light component in a certain direction and absorbing light of a linearly polarized light component in a direction orthogonal thereto can be used. As the reflective polarizer, a reflective polarizer having a function of transmitting linearly polarized light in a certain direction and reflecting linearly polarized light in a direction orthogonal thereto is used. Such a reflective polarizer is disclosed in International Publication WO95 / 01788.
And the like.

In another aspect of the first liquid crystal device, the ellipticity of the light incident on the liquid crystal layer from the other side becomes 0.85 or more when transmitted through the semi-transmissive reflection layer. The transmission axis of the polarizing plate or the reflection polarizing plate, the axis of the retardation plate, and the retardation value are set.

In this embodiment, the light incident on the liquid crystal layer from the back side of the liquid crystal cell is circularly polarized light or elliptically polarized light having a high ellipticity (ie, close to circularly polarized light), so that the first liquid crystal device having a higher transmission display contrast. Is realized. In another aspect of the first liquid crystal device, the retardation plate includes a quarter-wave plate.

According to this aspect, by making the retardation plate a quarter-wave plate, the light that has been linearly polarized by the second polarizing plate can be incident on the semi-transmissive reflection layer as complete circularly polarized light. it can. As disclosed in JP-A-5-100114, a method using a broadband circularly polarizing plate in which a half-wave plate and a quarter-wave plate are laminated, a 3 / 4-wave plate, and a 5 / 4-wave plate It is also possible to obtain circularly polarized light by using a method such as However, in the latter case, since the wavelength region in which good circularly polarized light is obtained is narrow, the method using one quarter-wave plate is more preferable.

In another embodiment of the first liquid crystal device, a liquid crystal polymer exhibiting a cholesteric phase is used as an optical element. Note that such a liquid crystal polymer has a function of selectively reflecting and transmitting circularly polarized light depending on the direction of rotation. Incidentally, such a liquid crystal polymer is disclosed in JP-A-8-271.
No. 89 discloses the details.

According to another aspect of the first liquid crystal device,
The lighting device may further include a lighting device disposed on a side of the optical element different from the liquid crystal layer.

According to this aspect, since the light emitted from the illumination device can be made incident from the back side of the liquid crystal cell, when the liquid crystal device is used in a dark place, the light from the illumination device is used for the transmission type display. Becomes possible.

In a second liquid crystal device according to the present invention, there is provided a liquid crystal cell having a liquid crystal layer between a first substrate and a second substrate arranged opposite to the first substrate, and a liquid crystal cell on the liquid crystal layer side of the second substrate. A semi-transmissive reflective layer disposed on a surface, for reflecting and transmitting incident light at a predetermined reflectance and transmittance, an illumination device disposed on a side of the second substrate different from the liquid crystal layer, and the liquid crystal cell A polarizing plate or a reflective polarizing plate disposed between the polarizing plate and the lighting device, and a linearly polarized light disposed between the polarizing plate and the liquid crystal cell and emitted from the lighting device and passing through the polarizing plate. A phase difference plate that converts the light that has become circularly polarized light or elliptically polarized light, and the rotation direction of the circularly polarized light or elliptically polarized light that has been emitted from the illumination device and passed through the phase difference plate, and the dark display state Incident from the first substrate side and reflected by the transflective plate The rotation direction of polarized light or elliptically polarized light, wherein the match.

The transflective layer used in the second liquid crystal device is a layer that reflects and transmits light with a certain reflectance and transmittance, such as a metal film having a very narrow slit,
A thin metal film or the like is suitable as a transflective plate.

According to the second liquid crystal device of the present invention, the light from the illumination device that has passed through the second polarizing plate and has become linearly polarized light is converted into circularly polarized light or elliptically polarized light by the phase difference plate. The rotation direction of the circularly polarized light or the elliptically polarized light coincides with the rotational direction of the circularly polarized light that enters from the first polarizing plate side, passes through the liquid crystal layer in a dark display state, and is reflected by the semi-transmissive reflection layer. Therefore, high contrast characteristics are realized in transmissive display. Furthermore,
Since no substrate is interposed between the transflective layer and the liquid crystal layer, there is no problem such as a double image of reflective display due to parallax.

In one embodiment of the second liquid crystal device, the second polarizer or the reflective polarizer is such that the ellipticity of polarized light emitted from the illumination device and passing through the phase difference plate is 0.85 or more. , The axis of the phase difference plate and the retardation value are set.

In another aspect of the second liquid crystal device, the retardation plate includes at least one quarter-wave plate. As disclosed in JP-A-5-100114, a method using a broadband circularly polarizing plate in which a １ ／ wavelength plate and a 波長 wavelength plate are laminated, a 、 ３ wavelength plate,
Circularly polarized light can also be obtained by a method using a / 4 wavelength plate or the like. However, in the latter case, since the wavelength region in which good circularly polarized light is obtained is narrow, the method using one quarter-wave plate is more preferable.

A third liquid crystal device according to the present invention comprises a liquid crystal cell having a liquid crystal layer between a first substrate and a second substrate disposed opposite to the first substrate, and a surface of the second substrate on the liquid crystal layer side. A semi-transmissive reflector that reflects and transmits incident light at a predetermined reflectance and transmittance, an illumination device disposed on a side of the second substrate different from the liquid crystal layer, and the liquid crystal cell. A selective reflection layer disposed between the illumination device and the illumination device, for selectively reflecting and transmitting circularly polarized light or elliptically polarized light according to the direction of rotation thereof, and emitted from the illumination device and transmitted through the selective reflection layer. The rotation direction of the circular knitted light coincides with the rotation direction of the circularly polarized light incident from the first substrate and reflected by the transflective plate in the dark display state.

In the third liquid crystal device of the present invention, of the light from the illumination device, circularly polarized light or elliptically polarized light in a certain rotation direction passes through the selective reflection layer. The rotation direction is the same as the rotation direction of the circular or elliptically polarized light that is incident from the first polarizing plate side, passes through the liquid crystal layer in the dark display state, and is reflected by the transflective plate. Therefore, high contrast characteristics are realized in transmissive display. Further, since the substrate is not interposed between the transflective layer and the liquid crystal layer, there is no problem such as a double image of reflective display due to parallax. Further, the light reflected by the selective reflection layer is also diffused on the surface of the lighting device, and a part of the light is transmitted through the selective reflection layer, so that the efficiency of use of light emitted from the lighting device is improved.

In one aspect of the third liquid crystal device, the selective reflection layer is a selective reflection layer using selective reflection using cholesteric liquid crystal.

In another embodiment of the third liquid crystal device, the selective reflection layer is, for example, a film-shaped circularly polarized light reflection plate utilizing selective reflection of cholesteric liquid crystal, which transmits right circularly polarized light and transmits a left circularly polarized light. It has a function of reflecting polarized light or transmitting left circular polarized light and reflecting right circular polarized light. The details of such a selective reflection layer are disclosed in JP-A-8-27189.

An electronic apparatus according to the present invention is an electronic apparatus including a liquid crystal device as a display unit, wherein a first liquid crystal device, a second liquid crystal device, or a third liquid crystal device is mounted as the liquid crystal device. And

According to the electronic device provided with the first liquid crystal device, an electronic device having good contrast characteristics of transmissive display is realized.

Further, in the electronic device provided with the second or third liquid crystal device, an electronic device having good contrast characteristics of transmissive display and no double reflection due to parallax is realized.

In the first, second and third liquid crystal devices of the present invention, the direction of rotation of circularly polarized light or elliptically polarized light is the direction of rotation of the electric field vector of light. The so-called “left circularly polarized light” and “right circularly polarized light,” “left”
"Right" indicates the direction of rotation. In the first, second, and third liquid crystal devices of the present invention, the liquid crystal layer in a dark display state refers to a liquid crystal layer to which a voltage necessary to obtain a sufficiently dark display is applied. That is, in a normally black display, it refers to a liquid crystal layer when no voltage is applied or when a non-selection voltage is applied, and in a normally white display, it refers to a liquid crystal layer when a selection voltage is applied.

In the first liquid crystal device, the second liquid crystal device and the third liquid crystal device according to the present invention, the circularly polarized light or the elliptically polarized light is an object of the present invention if it is light within a predetermined wavelength range within the visible wavelength region. Can be achieved, but preferably, when the light emitted from the illuminating device is a colored light, it is near its maximum intensity wavelength, and when the light emitted from the illuminating device is white light, the green wavelength at which human visibility is the highest is preferably obtained. It is preferable that circularly polarized light or elliptically polarized light with high ellipticity be obtained. Of course, it is ideal if circularly polarized light or elliptically polarized light having a uniform ellipticity can be obtained for all wavelength lights in the visible wavelength region.

The first liquid crystal device, the second liquid crystal device, and the third
In a liquid crystal device, it is optimal to obtain circularly polarized light in order to secure the contrast, but there is a case where the liquid crystal device is intentionally shifted from circularly polarized light in order to improve the brightness of the transmissive display.
When the ellipticity is smaller than 0.85, the contrast of the transmissive display is lower than the contrast of the reflective display.

Hereinafter, the display operation of the liquid crystal device of the present invention will be described in more detail.

First, the light incident from the second polarizing plate side becomes circularly polarized light or elliptically polarized light when transmitted through the semi-transmissive reflecting plate. The reason why the rotation direction of the circularly polarized light or the elliptically polarized light reflected by the semi-transmissive reflection plate through the liquid crystal layer in the state will increase the contrast of the transmissive display will be described. In the following description, it is assumed that light incident from the second polarizing plate side becomes circularly polarized light when passing through the semi-transmissive reflecting plate. Principle is the same.

In the single-polarizer type anti-liquid crystal display mode used in the first, second and third liquid crystal devices of the present invention, light incident from the first polarizer side is in a dark display state. The fact that the light is converted into circularly polarized light when it passes through the liquid crystal layer and is reflected on the transflective surface will be described with reference to FIG.

FIG. 12 (a) shows a reflection type liquid crystal device of a single polarizing plate type. Reference numeral 1201 denotes a polarizing plate, 1202 denotes a reflecting plate, and 1211 denotes a liquid crystal layer in a dark display state. substrate,
Members such as an alignment film and a transparent electrode are omitted since they are not particularly necessary for explaining the function. In addition, a retardation plate may be provided between the polarizing plate and the liquid crystal layer. However, if the retardation plate is regarded as the first liquid crystal layer, the following description can be applied as it is, so that it is omitted.

Now, since the display is in a dark state, the polarizing plate 1
The linearly polarized light incident from 201 reciprocates in the liquid crystal layer 1211 and is converted into linearly polarized light orthogonal to the incident polarized light, and is absorbed by the polarizing plate 1201.

FIG. 12B shows a virtual center plane 120.
3 shows a structure in which a polarizing plate 1204 and a liquid crystal layer 1212 are arranged so as to be mirror-symmetric with respect to the polarizing plate 1201 and the liquid crystal layer 1211. The reflection type liquid crystal device of the single polarizer type in FIG. 12 (a) is equivalent to the transmission type liquid crystal device of the dual polarizer type in FIG. 12 (b). Here, the polarizing plate 120
The linearly polarized light incident from No. 1 is applied to the liquid crystal layers 1211 and 1212.
Thus, the light should be converted to linearly polarized light orthogonal to the light, and absorbed by the polarizing plate 1204. At this time, what is the polarization state on the center plane?

Let us assume one structure. FIG. 12C shows that the liquid crystal layer 1212 and the polarizing plate 1204 are rotated by 90 degrees in FIG.
3 and a structure converted into a polarizing plate 1205 are shown. In this structure, the liquid crystal layers located symmetrically with respect to the center plane 1203 are orthogonal to each other at least as far as the normal direction of the center plane is viewed. That is, since the fast axis and the slow axis overlap each other, the phase difference is compensated. Therefore, the linearly polarized light incident from the polarizing plate 1201 is reflected by the liquid crystal layer 1.
After being variously converted by 211 and 1213, the light returns to the original linearly polarized light, is absorbed by the polarizing plate 1205, and a dark display is obtained.

The structure shown in FIG. 12B is replaced with the structure shown in FIG.
If the structure is equivalent to the structure shown in FIG. 12, (c) in FIG. The condition under which both are equivalent is that the center plane 1203
Does not change even if the polarization state is rotated by 90 degrees. There are only two such polarization states. That is, right circularly polarized light and left circularly polarized light. Accordingly, it was shown that light passing through the liquid crystal layer in the dark display state was converted into circularly polarized light and reached the reflection surface.

If the above is clear, the rest of the description is easy. In FIG. 13, the reflection display is performed as follows. The incident light 1311 from the outside is
01 and becomes a right circularly polarized light 1322 through the liquid crystal layer in the dark display state, and reaches the transflective plate 1302. Here, the reflected light changes the traveling direction of the light, and is converted into left-handed circularly polarized light 1322.
The linearly polarized light 1323 passes through the liquid crystal layer in the dark display state again.
And absorbed by the polarizing plate 1301.

Now, in order to obtain a high contrast in the transmissive display, the dark display must be sufficiently dark. That is, when the incident light 1312 from behind is transmitted through the semi-transmissive reflector, the left circularly polarized light 1322 is the same as in the case of the reflective display.
It should just be converted to.

Conversely, if the light is converted into right-handed circularly polarized light, a bright display is obtained, and a negative display is obtained in which the reflection display and the light / dark are reversed.

[0058]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a view showing a liquid crystal device according to the present invention. The first embodiment basically relates to a simple matrix type liquid crystal device, but can be applied to an active matrix type device with a similar configuration.

The configuration of the liquid crystal device will be described with reference to FIG. 101 is a first polarizing plate, 102 is a first retardation plate 103
Is a second retardation plate, 104 is a forward scattering plate, 105 is a first substrate, 106 is a liquid crystal layer, 107 is a second substrate, and 108 is a third substrate.
A retardation plate, 109 is a second polarizing plate, 111 and 112 are illumination devices, 111 is a light guide, and 112 is a light source.
121 is a color filter, 122 is a scanning electrode, 12
Reference numeral 3 denotes a semi-transmissive reflection plate also serving as a signal electrode. Here the first
Although the substrate 104 and the second substrate 106 are drawn widely apart, this is for clarity of the drawing, and they are actually opposed with a narrow gap of several μm to several tens μm. In addition to the components shown in the figure, elements such as a liquid crystal alignment film, an upper and lower short-circuit preventing film, an overcoat layer, a spacer ball, a sealant, a black mask, an anti-glare film, a liquid crystal driver IC, and a driving circuit may be necessary in some cases. However, they are not necessary for describing the features of the present invention, and are omitted here.

Next, each component will be described. The first polarizing plate 101 and the second polarizing plate 109 have a function of absorbing a predetermined linearly polarized light component and transmitting other polarized light components.

The first retardation plate 102 and the second retardation plate 10
Third, the third retardation plate 108 is a uniaxially stretched film of a polycarbonate resin or a polyvinyl alcohol resin. The third retardation plate 108 is an essential element in the present invention, but the first retardation plate 102 and the second retardation plate 103
It is used to compensate for the coloring of the liquid crystal,
It is possible to use only one sheet, and in the case of a TN liquid crystal, it is often omitted.

The forward scattering plate 104 is provided for the purpose of diffusing the specular reflection of the semi-transmissive reflection plate, and a film composed of two types of minute regions having different refractive indexes can be used. With this configuration, a light scattering plate having strong forward scattering and small back scattering can be obtained. Specifically, a plastic film in which fine beads are dispersed in a transparent binder having a different refractive index from the fine beads can be used. Alternatively, a plastic film in which two types of minute regions having different refractive indices form a layer structure and scatter only light incident from a specific angle may be used.

If a scattering function is to be provided without using a forward scattering plate, a scattering layer may be provided on the inner surface of the liquid crystal cell, or a scattering structure may be given to the transflective plate itself. As the first substrate 105 and the second substrate 107, a transparent glass substrate is suitable. Further, a liquid crystal device which is lightweight and hard to break can be formed by using a plastic substrate. However,
Since the liquid crystal device of the present invention performs not only reflective display but also transmissive display, both substrates must be transparent at least in a partial wavelength region of visible light.

The liquid crystal layer 106 mainly contains a STN liquid crystal composition twisted from 210 ° to 270 °, but a TN liquid crystal composition twisted by 90 ° may be used when the display capacity is small. The twist angle is determined by the orientation direction of the upper and lower glass substrates and the amount of the chiral agent added to the liquid crystal.

As the lighting device, the light guide plate 111 and the light source 1
Twelve combinations are most common. A diffusing plate or a condensing prism may be laminated on the light guide plate. A cold cathode tube or an LED (light emitting diode) can be used as the light source. Instead of such a lighting device combining a light guide and a light source, an EL (electroluminescent) or the like which is a surface light source may be used. In the first embodiment, a white cold cathode tube was used.

As the color filter 121, a filter having a higher transmittance and a lighter color than that used in a transmission type color liquid crystal device was used in order to obtain a bright display even with reflection. A black mask may be provided as needed. This color filter can also be provided on a semi-transmissive reflection plate on the second substrate side. Of course, in the case of monochrome display, no color filter is required.

The scanning electrode 122 is made of a striped transparent electrode, for example, ITO.

As the transflective plate 123, a film in which a pearl pigment is dispersed in a resin is generally used, but it is difficult to form this in a liquid crystal cell. Therefore, three methods shown in FIGS. 2A, 2B, and 2C have been devised.

In FIG. 2A, reference numeral 201 denotes a semi-transmissive reflection plate serving also as a signal electrode provided on the second substrate, and reference numeral 202 denotes a scanning electrode made of ITO provided on the first substrate. The area to be changed is a pixel area (dot).
The hatched area 201 is an Al sputtered film having a thickness of 200 Å, and functions as a semi-transmissive reflector that transmits about 8% of light and reflects the remaining light.

In FIG. 2B, reference numeral 203 denotes a semi-transmissive reflector provided on the second substrate and serving also as a signal electrode.
Reference numeral 2 denotes a scanning electrode made of ITO provided on the first substrate. The hatched area 203 is an Al sputtered film having a thickness of 2000 Å and hardly transmits light. However, since a plurality of slits 204 having a width of 2 μm are provided, light incident on the slit area is transmitted. Since the liquid crystal in the slit region 204 operates almost in the same manner as the region on the Al film due to the oblique electric field generated between the slit region 204 and the opposing scan electrode, transmission display is possible. However, since the threshold voltage of transmissive display changes by about 0.04 V every time the slit width changes by 1 μm, it is necessary to strictly control the slit width to have a uniformity of at least ± 10% especially in simple matrix driving. There is.

FIG. 2C shows an example in which the signal electrode and the transflective plate are separated from each other. 205 is a transflective plate provided on the second substrate, and 207 is the entire surface of the second substrate 205. The signal electrode 202 made of ITO provided so as to cover the first electrode 202
This is a scanning electrode made of ITO provided on a substrate. The hatched area of the second substrate 205 is also an Al sputtered film having a thickness of 2,000 Å, and hardly transmits light, but has a square opening 206 close to a square, so that light in that area is transmitted. Further, since the signal electrode 207 made of ITO is covered on the second substrate 205 via the SiO2 insulating film, the liquid crystal in the opening 206 also operates normally, and transmissive display is possible.

Next, the panel conditions of the liquid crystal device of this embodiment will be described with reference to FIG. In FIG. 3, the stacked 5
The rectangles indicate layers of a first polarizing plate, a first second retardation plate, a liquid crystal cell, a third retardation plate, and a second polarizing plate in order from the top, and the axial direction is indicated by an arrow drawn on each rectangle. Indicated.

The absorption axis direction 301 of the first polarizing plate is 35.5 degrees to the left with respect to the longitudinal direction of the panel. The delay axis direction 302 of the first retardation plate is 10
2.5 degrees and the retardation is 455 nm. The delay axis direction 303 of the second phase difference plate is 48.5 degrees to the left with respect to the longitudinal direction of the panel, and its retardation is 544 nm. The rubbing direction 304 of the first substrate of the liquid crystal cell is 37.5 degrees to the right with respect to the longitudinal direction of the panel. The rubbing direction 305 of the second substrate of the liquid crystal cell is 37.5 degrees to the left with respect to the longitudinal direction of the panel. The liquid crystal is twisted 255 degrees counterclockwise from the first substrate toward the second substrate. The product of the birefringence Δn of the liquid crystal and the cell gap d is 0.90 μm. Delay axis direction 3 of third retardation plate
06 is 0.5 degrees to the right with respect to the longitudinal direction of the panel, and its retardation is 140 nm. The absorption axis direction 307 of the second polarizing plate is at the left 49.
5 degrees.

At this time, the light emitted from the illumination device passes through the semi-transmissive reflection plate in the state of green light having a wavelength of 560 nm and elliptically polarized light having an ellipticity of 0.85. The rotation direction is clockwise, and the polarization state is substantially the same as that of the light incident from the first polarizing plate side, passing through the liquid crystal layer in the dark display state, and reflected by the transflective plate.

FIG. 4 shows the electro-optical characteristics of the liquid crystal device of this embodiment. The horizontal axis is the applied voltage, and the vertical axis is the reflectance or transmittance. Reference numeral 401 denotes a voltage reflectance curve for reflective display,
Reference numeral 402 denotes a voltage transmittance curve of the transmissive display. The same normally black display is used for both the reflective display and the transmissive display.
When multiplex driving was performed at 1/240 duty, the contrast of the reflective display was 1: 8.0, the brightness was 24%, the contrast of the transmissive display was 1: 8.1, and the brightness was 3.9%. Was.

The second direction with respect to the longitudinal direction of the panel in FIG.
When the angle θ formed by the absorption axis direction 307 of the polarizing plate was variously changed, the ellipticity when the light emitted from the illumination device passed through the semi-transmissive reflection plate, and the contrast and brightness of the transmissive display were measured. Was obtained.

From these results, it is understood that it is important to make the ellipticity as close to 1 as possible, that is, to make circularly polarized light in order to obtain high contrast in transmissive display.
On the other hand, circular polarization is not always the best in terms of brightness. Therefore, it is necessary to set the ellipticity in consideration of the balance between contrast and brightness.

According to the configuration of the present embodiment as described above,
A transflective liquid crystal device capable of high-quality reflective display without parallax and high-contrast transmissive display was provided.

(Comparative Example 1) In the first embodiment, what kind of display is obtained when the light emitted from the illumination device and passing through the transflective plate is not right circularly polarized light but left circularly polarized light. I wonder.

While the structure of the liquid crystal device shown in FIGS. 1 and 2 was maintained, only the panel conditions were changed as shown in FIG. In FIG. 5, five stacked rectangles indicate, in order from the top, layers of a first polarizing plate, a first second retardation plate, a liquid crystal cell, a third retardation plate, and a second polarizing plate. The axial direction is indicated by the arrow drawn in FIG.

The absorption axis direction 501 of the first polarizing plate is 35.5 degrees to the left with respect to the longitudinal direction of the panel. The delay axis direction 502 of the first retardation plate is 10
2.5 degrees and the retardation is 455 nm. The delay axis direction 503 of the second retardation plate is 48.5 degrees to the left with respect to the longitudinal direction of the panel, and its retardation is 544 nm. The rubbing direction 504 of the first substrate of the liquid crystal cell is 37.5 degrees to the right with respect to the longitudinal direction of the panel. The rubbing direction 505 of the second substrate of the liquid crystal cell is 37.5 degrees to the left with respect to the longitudinal direction of the panel. The liquid crystal is twisted 255 degrees counterclockwise from the first substrate toward the second substrate. The product of the birefringence Δn of the liquid crystal and the cell gap d is 0.90 μm. Delay axis direction 5 of third retardation plate
06 is 0.5 degrees to the right with respect to the longitudinal direction of the panel, and its retardation is 140 nm. The absorption axis direction 507 of the second polarizing plate is 13
9.5 degrees.

At this time, the light emitted from the illuminating device passes through the semi-transmissive reflection plate in a state of green light having a wavelength of 560 nm and elliptically polarized light having an ellipticity of 0.85. However, the rotation direction is counterclockwise, that is, the rotation is opposite to the elliptically polarized light that is incident from the first polarizing plate side, passes through the liquid crystal layer in the dark display state, and is reflected by the semi-transmissive reflection plate.

FIG. 6 shows the electro-optical characteristics of the liquid crystal device of this comparative example. The horizontal axis is the applied voltage, and the vertical axis is the reflectance or transmittance. Reference numeral 601 denotes a voltage reflectance curve of the reflective display,
Reference numeral 602 denotes a voltage transmittance curve of the transmissive display. The reflective display is a normally black display similar to that of the liquid crystal device of the first embodiment. However, the transmissive display is a normally white display, so the display is inverted, and high contrast cannot be obtained because black is floating. .

As described above, elliptically polarized light close to circularly polarized light which is emitted from the illumination device and passes through the semi-transmissive reflection plate, and the semi-transmissive reflection plate which passes through the liquid crystal layer which is incident from the first polarizing plate side and is in a dark display state. If the elliptically polarized light that is close to the reflected circularly polarized light is rotated in the reverse direction, normal transmission display cannot be performed.

(Second Embodiment) FIG. 7 is a view showing a liquid crystal device according to a second embodiment. The second embodiment basically relates to an active matrix type liquid crystal device, but can be applied to a simple matrix type device with a similar configuration.

The configuration will be described with reference to FIG. 701 is a first polarizer, 702 is a first retarder 703 is a second retarder, 704 is a first substrate, 705 is a liquid crystal layer, and 706 is a second polarizer.
A substrate, 707 is a third retardation plate, 708 is a fourth retardation plate,
709 is a second polarizing plate, 711 and 712 are illumination devices, 711 is a light guide, and 712 is a light source. 721
Denotes a color filter, 722 denotes a scanning electrode, 723 denotes a semi-transmissive reflection plate also serving as a pixel electrode, 724 denotes a signal electrode, and 725 denotes a TFD (thin film diode) element. Here, the first substrate 704 and the second substrate 706 are drawn widely apart, but this is for the sake of clarity of the drawing, and actually,
They face each other with a narrow gap of m to tens of μm.
In addition to the components shown in the figure, elements such as a liquid crystal alignment film, an upper and lower short-circuit preventing film, an overcoat layer, a spacer ball, a sealant, a black mask, an anti-glare film, a liquid crystal driver IC, and a driving circuit may be necessary in some cases. However, they are not necessary for describing the features of the present invention, and thus are omitted.

Next, each component will be described. As the polarizing plate, the retardation plate, the first substrate, the lighting device, the color filter, the scanning electrode, and the transflective plate, those similar to those in Example 1 were used. The signal electrode 724 was formed of metal Ta. TFD
The element 725 is composed of an insulating film Ta2O5 formed of metal Ta and Al-Nd.
It has an MIM (metal-insulating film-metal) structure sandwiched between alloys. For the second substrate 706, glass having an uneven shape formed on the surface was used. Therefore, since the transflective plate 723 is a diffused reflector having an uneven structure, the forward scattering plate used in the first embodiment is not required.

Next, the panel conditions of the liquid crystal device of this embodiment will be described with reference to FIG. In FIG. 8, the stacked 5
The rectangles indicate layers of a first polarizing plate, a first second retardation plate, a liquid crystal cell, a third fourth retardation plate, and a second polarizing plate in this order from the top, and the axis is indicated by an arrow drawn on each rectangle. Direction indicated.

The absorption axis direction 801 of the first polarizing plate is 110 degrees to the left with respect to the longitudinal direction of the panel. The delay axis direction 802 of the first phase difference plate is at the left 127.
5 degrees and the retardation is 270 nm. The delay axis direction 803 of the second retardation plate is 10 degrees to the left with respect to the longitudinal direction of the panel, and the retardation is 1 degree.
40 nm. Rubbing direction 8 of first substrate of liquid crystal cell
04 is 51 degrees to the right with respect to the panel longitudinal direction. The rubbing direction 805 of the second substrate of the liquid crystal cell is at left 50 degrees with respect to the longitudinal direction of the panel. The liquid crystal is moved from the first substrate to the second
Twist 79 degrees clockwise toward the substrate. The product of the birefringence Δn of the liquid crystal and the cell gap d is 0.24 μm
It is. The delay axis direction 806 of the third retardation plate is 100 degrees to the left with respect to the longitudinal direction of the panel, and its retardation is 140 nm. Delay axis direction 80 of fourth retardation plate
7 is 37.5 degrees to the left with respect to the longitudinal direction of the panel, and its retardation is 270 nm. The absorption axis direction 808 of the second polarizing plate is at left 20 degrees with respect to the panel longitudinal direction.

At this time, the light emitted from the illuminating device is in a relatively wide wavelength range centered on green light having a wavelength of 560 nm, and is in the state of elliptically polarized light having an ellipticity of 0.96 at the maximum, which is very close to circularly polarized light. Passes through the transmissive reflector. The rotation direction is counterclockwise, and the polarization state is substantially the same as the light incident from the first polarizing plate side, passing through the liquid crystal layer in the dark display state, and reflected by the semi-transmissive reflection plate.

FIG. 9 shows the electro-optical characteristics of the liquid crystal device of this embodiment. The horizontal axis is the applied voltage, and the vertical axis is the reflectance or transmittance. Reference numeral 901 denotes a voltage reflectance curve of the reflective display,
Reference numeral 902 denotes a voltage transmittance curve for transmissive display. The same normally white display is used for both reflective display and transmissive display.
Very high contrast is obtained.

According to the configuration of the present embodiment as described above,
The contrast is higher than the liquid crystal device of the first embodiment,
In addition, a transflective liquid crystal device capable of performing reflective display and transmissive display with less unnecessary coloring can be provided.

(Third Embodiment) The third embodiment shows another example of an illuminating device applicable to the transflective liquid crystal devices of the first and second embodiments. In the third embodiment, instead of the lighting devices 111 and 112 in FIG. 1 or the lighting devices 711 and 712 in FIG. 7, a blue EL having an emission peak at a wavelength of 480 nm is used. Therefore, a film having a retardation of 120 nm was used for the second retardation plate so that the light emitted from the illumination device was converted into elliptically polarized light having a high ellipticity with blue light having a wavelength of 480 nm. According to the configuration of the present embodiment as described above, it is possible to provide a transflective liquid crystal device capable of high-contrast transmissive display even when using a colored illumination device in which emitted light is colored. .

(Fourth Embodiment) The fourth embodiment is an example of a reflective polarizing plate applicable to the transflective liquid crystal devices of the first to third embodiments. The third embodiment is different from the third embodiment in that a reflective polarizer is used instead of the second polarizer 109 of FIG. 1 or the second polarizer 709 of FIG.

As the reflective polarizing plate, a birefringent dielectric multilayer film was used. This birefringent dielectric multilayer film has a function of reflecting a predetermined linearly polarized light component and transmitting other polarized light components. For details of such a birefringent dielectric multilayer film, see an international application published internationally (international application number: WO97 / 01788) and Japanese Patent Application Laid-Open No. 9-5069.
No. 85 discloses this. Such a reflective polarizer is commercially available as DBEF (trade name) from 3M Corporation in the United States and is generally available.

The axial direction of the reflective polarizing plate was arranged such that the reflective axis was parallel to 307 in FIG.

As described above, by using the reflective polarizer as the second polarizer, the light that should have been absorbed by the second polarizer is reflected and can be reused. There was an effect that display brightness was improved by about 30%.

(Fifth Embodiment) FIG. 10 is a view showing the structure of a liquid crystal device according to a fifth embodiment. The configuration will be described based on FIG. 1001 is a first polarizing plate, 1002 is a first retardation plate, 1003 is a second retardation plate, 1004 is a forward scattering plate, 1005 is a first substrate, 1006 is a liquid crystal layer, 1007
Is a second substrate, 1008 is a circularly polarized light reflecting plate, 1011 and 10
Reference numeral 12 denotes a lighting device, 1011 denotes a light guide, 1012
Is a light source. Reference numeral 1021 denotes a color filter;
Reference numeral 2 denotes a scanning electrode, and 1023, a semi-transmissive reflection plate also serving as a signal electrode. Here, the first substrate 1005 and the second substrate 1007
Are drawn widely apart, but this is for the sake of clarity in the drawing, and in fact, they face each other with a narrow gap of several μm to several tens μm. In addition to the illustrated components, a liquid crystal alignment film, a vertical short prevention film, an overcoat layer, a spacer ball, a sealant, a black mask,
Elements such as an anti-glare film, a liquid crystal driver IC, and a driving circuit may be necessary in some cases, but are omitted because they are not particularly necessary for describing the features of the present invention.

Next, each component will be described. As the polarizing plate, the retardation plate, the forward scattering plate, the substrate, the illuminating device, the color filter, the scanning electrode, and the transflective plate, those similar to those in Example 1 were used.

The panel conditions such as the axial direction and the retardation of the liquid crystal device of this embodiment are also limited to those relating to the first polarizing plate, the first retardation plate, the second retardation plate, and the liquid crystal cell.
This is the same as the first embodiment shown in FIG. This embodiment is characterized in that a circularly polarized light reflecting plate transmitting the same right circularly polarized light is used as a selective reflection layer instead of the third retardation plate and the second polarizing plate.

As the circularly polarized light reflecting plate, a liquid crystal polymer exhibiting a cholesteric phase can be used. This has a function of reflecting a predetermined circularly polarized light component and transmitting other polarized light components. Details of such a polarization separating means are disclosed in Japanese Patent Application Laid-Open No. 8-271892.

At this time, the light emitted from the illuminating device passes through the semi-transmissive reflector in the state of elliptically polarized light having an ellipticity of 1.00, that is, circularly polarized light, in a relatively wide wavelength range centered on the wavelength of 560 nm. I do. The direction of rotation is clockwise,
The polarization state is substantially the same as that of the light incident from the first polarizing plate side, passing through the liquid crystal layer in the dark display state, and reflected by the transflective plate.

As described above, by using a reflective polarizer instead of the third retardation plate and the second polarizer, a transflective display is realized with a thin and inexpensive configuration. Further, since perfect circularly polarized light is obtained, there is an effect that high contrast can be obtained in transmissive display. Further, since the light that should have been absorbed by the second polarizing plate can be reused, there is also an effect that the brightness of the transmissive display is improved by about 30%.

(Sixth Embodiment) The sixth embodiment is an embodiment of a TFD active matrix liquid crystal element applicable to the transflective liquid crystal devices of the first, second and fifth embodiments. is there.

First, a configuration near a TFD drive element as an example of a two-terminal type nonlinear element used in the present embodiment will be described with reference to FIGS. 15 (a) and 15 (b). Here, FIG. 15A is a plan view schematically showing a TFD driving element together with a pixel electrode and the like, and FIG.
FIG. 16 is a sectional view taken along the line BB ′ of FIG. Note that FIG.
In (b), in order to make each layer and each member a recognizable size in the drawing, the scale is different for each layer and each member.

Referring to FIGS. 15A and 15B,
The TFD drive element 40 is formed on an insulating film 41 formed on the transparent substrate 2 with the insulating film 41 serving as a base. The first metal film 42, the insulating layer 44, and the second
It is composed of a metal film 46 and has a TFD structure (Thin Film Diod).
e) Or MIM structure (Metal Insulator Metal structure)
have. Then, the first metal film 42 of the TFD drive element 40
Is connected to a scanning line 61 formed on the transparent substrate 2, and the second metal film 46 is connected to a pixel electrode 62 made of a conductive reflection film, which is another example of the reflection electrode.
Note that a data line (described later) is formed on the transparent substrate 2 instead of the scanning line 61, and is connected to the pixel electrode 62 to form the scanning line 61.
May be provided on the counter substrate side.

The transparent substrate 2 is made of an insulating and transparent substrate such as glass or plastic. The insulating film 41 serving as a base is made of, for example, tantalum oxide.
However, the main purpose of the insulating film 41 is to prevent the first metal film 42 from peeling off from the base and not to diffuse impurities from the base into the first metal film 42 by a heat treatment performed after the deposition of the second metal film 46 or the like. Is formed. Therefore, when the transparent substrate 2 is made of a substrate having excellent heat resistance and purity, such as a quartz substrate, the insulating film 41 is omitted when peeling or diffusion of impurities does not pose a problem. be able to. The first metal film 42 is made of a conductive metal thin film, for example, tantalum alone or a tantalum alloy. The insulating film 44 is composed of, for example, an oxide film formed on the surface of the first metal film 42 in a chemical conversion solution by anodic oxidation. The second metal film 46 is made of a conductive metal thin film, for example, chromium alone or a chromium alloy.

In this embodiment, in particular, the pixel electrode 62 is provided with a light-transmitting region such as a rectangular or square slit or a fine opening as in each of the above-described embodiments, or a counter substrate for each pixel. It is formed smaller than the upper transparent electrode and is configured to allow light to pass therethrough.

Further, the pixel electrode 62, the TFD driving element 4
0, a transparent insulating film 29 is provided on the side facing the liquid crystal such as the scanning line 61 (upper surface in the figure), and is formed of an organic thin film such as a polyimide thin film on the predetermined orientation such as a rubbing process. The processed alignment film 19 is provided.

Although several examples of the TFD driving element as the two-terminal type nonlinear element have been described above, a bidirectional element such as a ZnO (zinc oxide) varistor, an MSI (Metal Semi-Insulator) driving element, or an RD (Ring Diode) is used. A two-terminal nonlinear element having a diode characteristic can be applied to the reflection type liquid crystal device of the present embodiment.

Next, the structure and operation of the transflective liquid crystal device of the sixth embodiment, which is provided with the TFD driving elements constructed as described above, of the TFD active matrix driving system will be described with reference to FIGS. This will be described with reference to FIG. Here, FIG. 16 is an equivalent circuit diagram showing the liquid crystal element together with a drive circuit, and FIG. 17 is a partially cutaway perspective view schematically showing the liquid crystal element.

Referring to FIG. 16, in the transflective liquid crystal device of the TFD active matrix drive system, a plurality of scanning lines 61 arranged on a transparent substrate 2 are connected to a Y driver circuit 100 constituting an example of a scanning line driving circuit. Connected
The plurality of data lines 60 arranged on the opposing substrate form an X driver circuit 110 constituting an example of a data line driving circuit.
It is connected to the. Note that the Y driver circuit 100 and the X driver circuit 110 may be formed on the transparent substrate 2 or its opposing substrate. In this case, a transflective liquid crystal device with a built-in drive circuit is provided. Alternatively, the Y driver circuit 100 and the X driver circuit 110 may be configured by an external IC independent of the transflective liquid crystal device, and may be connected to the scanning lines 61 and the data lines 60 via predetermined wiring.
In this case, the transflective liquid crystal device does not include a driving circuit.

In each pixel area of the matrix, the scanning line 60 is connected to one terminal of the TFD drive element 40 (see FIGS. 15A and 15B), and the data line 60 is a liquid crystal. It is connected to the other terminal of the TFD drive element 40 via the layer 3 and the pixel electrode 62. Therefore, a scanning signal is supplied to the scanning line 61 corresponding to each pixel area,
When a data signal is supplied to the data line 60, the TFD driving element 40 in the pixel region is turned on,
The pixel electrode 62 and the data line 6 are connected via the D drive element 40.
A drive voltage is applied to the liquid crystal layer 3 between 0. And
In a bright place, reflective display is performed by reflecting external light by the pixel electrode 62, and in a dark place, a transmissive display is performed by transmitting light from a backlight through a slit or the like of the pixel electrode 62.

In FIG. 17, the transflective liquid crystal device includes a transparent substrate 2 and a transparent substrate (opposite substrate) 1 disposed opposite to the transparent substrate. The transparent substrate 1 is made of, for example, a glass substrate. Pixel electrodes 62 are provided in a matrix on the transparent substrate 2, and each pixel electrode 62 is connected to a scanning line 61. The transparent substrate 1 is provided with a plurality of data lines 60 as transparent electrodes that extend in a direction intersecting the scanning lines 61 and are arranged in a strip shape. The data line 60 is made of, for example, a transparent conductive thin film such as an ITO (Indium Tin Oxide) film. Below the data line 60,
For example, an alignment film 9 made of an organic thin film such as a polyimide thin film and subjected to a predetermined alignment process such as a rubbing process is provided. Further, the transparent substrate 1 is provided with a color filter (not shown) made of a color material film arranged in a stripe shape, a mosaic shape, a triangle shape, or the like, depending on its use.

As described above, the TFD of the sixth embodiment
According to the transflective liquid crystal device of the active matrix driving system, it is possible to realize a color liquid crystal device capable of switching and displaying between a reflective display and a transmissive display without double reflection or blurring of display. In particular, the transflective liquid crystal device can be driven in a normally black mode by voltage control in the X and Y driver circuits 110 and 100 which constitute an example of the driving means.

(Seventh Embodiment) The seventh embodiment is an embodiment of a TFT active matrix type liquid crystal element applicable to the transflective liquid crystal devices of the first, second and fifth embodiments. is there.

FIG. 18 is an equivalent circuit diagram of various elements, wiring, etc. in a plurality of pixels formed in a matrix forming an image display area of the liquid crystal device.
FIG. 20 is a plan view of a plurality of pixel groups adjacent to each other on a transparent substrate on which scanning lines, pixel electrodes, and the like are formed.
It is C 'sectional drawing. In FIG. 20, the scale of each layer and each member is different so that each layer and each member have a size that can be recognized in the drawing.

In FIG. 18, the TFT active matrix type transflective liquid crystal device of the eleventh embodiment is
A plurality of TFTs 130 for controlling a pixel electrode 62, which is another example of a reflective electrode arranged in a matrix, are formed in a matrix, and a data line 135 to which an image signal is supplied is electrically connected to a source of the TFT 130. It is connected. The image signals S1, S2,
, Sn may be supplied line-sequentially in this order.
A plurality of data lines 135 adjacent to each other may be supplied for each group. Also, the TFT 130
The scanning lines 131 are electrically connected to the gates, and the scanning signals G1, G2,..., Gm are applied to the scanning lines 131 in a pulsed manner in this order at a predetermined timing. I have. The pixel electrode 62 is electrically connected to the drain of the TFT 130. By closing the switch of the TFT 130, which is a switching element, for a predetermined period, the image signals S1, S2,. Write at a predetermined timing.
The image signals S1, S2,..., Sn of a predetermined level written in the liquid crystal via the pixel electrodes 62 are held for a certain period between the counter electrodes (described later) formed on the counter substrate (described later). . Here, in order to prevent the held image signal from leaking, a storage capacitor 170 is added in parallel with a liquid crystal capacitor formed between the pixel electrode 62 and the counter electrode.

In FIG. 19, on a transparent substrate 2 as a TFT array substrate, pixel electrodes 62 (contours 62a are shown by dotted lines in the figure) formed of a reflective film in a matrix are provided. The data line 135, the scanning line 131, and the capacitor line 13 are respectively provided along the vertical and horizontal boundaries of the electrode 62.
2 are provided. The data line 135 is connected to the semiconductor layer 8 made of a polysilicon film or the like via the contact hole 85.
1a is electrically connected to the source region. The pixel electrode 62 is connected to the semiconductor layer 81 via the contact hole 88.
a is electrically connected to the drain region. The capacitance line 132 is opposed to the first storage capacitance electrode extending from the drain region of the semiconductor layer 1a via the insulating film, and forms the storage capacitance 170. In addition, the semiconductor layer 81
The scanning line 131 is arranged so as to face the channel region 81a 'indicated by a hatched region in FIG. As described above, each of the intersections of the scanning line 131 and the data line 135 is provided with a TFT 130 in which the scanning line 131 is opposed to the channel region 81a 'as a gate electrode.

As shown in FIG. 20, the liquid crystal device comprises a transparent substrate 2 and a transparent substrate (opposite substrate) 1 opposed thereto.
And Each of these transparent substrates 1 and 2 is made of, for example, an insulating and transparent substrate such as quartz, glass, or plastic.

In this embodiment, in particular, the pixel electrode 62 is provided with a light-transmitting region such as a rectangular or square slit or a fine opening as in each of the above-described embodiments, or a counter substrate for each pixel. It is formed smaller than the upper transparent electrode and is configured to allow light to pass therethrough.

Further, a transparent insulating film 29 is provided on the side (upper surface in the figure) of the pixel electrode 62, the TFT 130, etc., facing the liquid crystal, on which an organic thin film such as a polyimide thin film is formed. There is provided an alignment film 19 that has been subjected to a predetermined alignment process such as.

On the other hand, a counter electrode 121 as another example of a transparent electrode is provided on almost the entire surface of the transparent substrate 1, and a non-opening region of each pixel is provided with a black mask or a black matrix called a black matrix. Two light-shielding films 122 are provided. Below the counter electrode 121, an alignment film 9 made of an organic thin film such as a polyimide thin film and subjected to a predetermined alignment process such as a rubbing process is provided. Furthermore,
The transparent substrate 1 is provided with a color filter (not shown) made of color material films arranged in a stripe shape, a mosaic shape, a triangle shape, or the like, depending on the application.

On the transparent substrate 2, a pixel switching TFT 130 for controlling the switching of each pixel electrode 62 is provided at a position adjacent to each pixel electrode 62.

[0126] A sealing material is provided between the pair of transparent substrates 1 and 2 having the above-mentioned structure and arranged so that the pixel electrode 62 and the opposing electrode 121 face each other, as in the first embodiment. Liquid crystal is sealed in the enclosed space, and the liquid crystal layer 3 is formed.

Further, a plurality of pixel switching TFTs 3
Below 0, a first interlayer insulating film 112 is provided.
The first interlayer insulating film 112 functions as a base film for the pixel switching TFT 30 by being formed on the entire surface of the transparent substrate 2. The first interlayer insulating film 112 is made of, for example, NSG (non-doped silicate glass), PSG
(Phosphorus silicate glass), BSG (boron silicate glass), BPSG (boron phosphor silicate glass), or other high insulating glass, or a silicon oxide film, a silicon nitride film, or the like.

In FIG. 20, the pixel switching TF
T130 is connected to the data line 1 via the contact hole 85.
It comprises a source region connected to 35, a channel region 81 a ′ opposed to the scanning line 131 via a gate insulating film, and a drain region connected to the pixel electrode 62 via a contact hole 88. Data line 13
Reference numeral 1 denotes a light-shielding and conductive thin film such as a low-resistance metal film such as Al or an alloy film such as metal silicide. In addition, contact holes 85 and 88
A second interlayer insulating film 114 is formed,
Further, a third interlayer insulating film 117 having a contact hole 88 formed thereon is formed thereon. These second and third interlayer insulating films 114 and 117 also have NSG, PSG, BSG, B
It is made of highly insulating glass such as PSG, or a silicon oxide film, a silicon nitride film, or the like.

The pixel switching TFT 130 is an LD
The TFT may have any structure such as a D structure, an offset structure, and a self-aligned structure. Further, in addition to the single gate structure, the TFT 130 may be configured with a dual gate or a triple gate or more.

(Eighth Embodiment) Three examples of electronic equipment according to the present invention will be described. The liquid crystal device of the present invention is suitable for portable equipment used in various environments and requiring low power consumption.

FIG. 11A shows a mobile phone, and the main body 11
A display unit 1102 is provided at an upper part of the front surface of the display unit 01. Mobile phones are used in all environments, both indoors and outdoors.
Especially, it is often used in cars, but the inside of cars at night is very dark. Therefore, as a display device used for a mobile phone, a transflective liquid crystal device capable of performing a transmissive display using auxiliary light as needed, mainly a reflective display with low power consumption is desirable. The liquid crystal device of the present invention is brighter and has a higher contrast ratio than the conventional liquid crystal device in both reflective display and transmissive display.

FIG. 11 (b) shows a watch,
A display unit 1104 is provided at the center of the display unit 03. An important aspect in watch applications is luxury. The liquid crystal device of the present invention not only has a high contrast, but also has no double image due to parallax, so that a very high-quality display can be obtained as compared with the conventional liquid crystal device. The display can be confirmed even in darkness.

FIG. 11C shows a portable information device, in which a display unit 1106 is provided above a main body 1105 and an input unit 110 is provided below.
7 are provided. Conventionally, such portable information devices often use a reflection type monochrome liquid crystal device. This is because the transmissive color liquid crystal device always uses a backlight, consumes large power, and has a short continuous use time. In such a case, if a transflective color liquid crystal device as in the present invention is used, color display can be performed with low power consumption, and a bright display can be obtained by turning on a backlight in a dark environment. Therefore, a portable information device which is very easy to use can be obtained.

The liquid crystal device according to the present invention can be used as various display devices capable of displaying a high-contrast image both in a dark place and in a bright place. It can be used as a device. Further, the electronic apparatus according to the present invention is a liquid crystal television, a viewfinder type or a monitor direct-view type video tape recorder, a car navigation device, an electronic organizer, a calculator, a word processor, a work station, and a mobile phone. It can be used as a telephone, videophone, POS terminal, touch panel, etc.

[Brief description of the drawings]

FIG. 1 shows a first embodiment, a third embodiment, a fourth embodiment, and a sixth embodiment.
2 shows the structure of the liquid crystal device according to the example and the comparative example.

FIG. 2 shows a first embodiment, a third embodiment, a fourth embodiment, and a sixth embodiment.
9 shows a structure of a transflective plate used in the liquid crystal devices according to the example and the comparative example.

FIG. 3 shows panel conditions of the liquid crystal device according to the first embodiment, the third embodiment, and the fourth embodiment.

FIG. 4 shows electro-optical characteristics of the liquid crystal device according to the first embodiment.

FIG. 5 shows panel conditions of the liquid crystal device according to Comparative Example 1.

FIG. 6 shows electro-optical characteristics of the liquid crystal device according to Comparative Example 1.

FIG. 7 shows a structure of a liquid crystal device according to a second embodiment.

FIG. 8 shows panel conditions of the liquid crystal device according to the second embodiment.

FIG. 9 shows electro-optical characteristics of the liquid crystal device according to the second embodiment.

FIG. 10 shows a structure of a liquid crystal device according to a fifth embodiment.

11A and 11B show an electronic device according to an eighth embodiment, wherein FIG. 11A shows a mobile phone, FIG. 11B shows a watch, and FIG. 11C shows a mobile information device.

FIG. 12 is a diagram illustrating a display operation of the liquid crystal device according to the first to sixth embodiments.

FIG. 13 is a diagram illustrating a display operation of the liquid crystal device according to the first to sixth embodiments, and is a diagram illustrating a transition of the polarization state of the reflective display and the transmissive display.

FIG. 14 is a diagram illustrating contrast characteristics and brightness of the liquid crystal device according to the first embodiment.

FIG. 15A shows a TF according to a sixth embodiment of the present invention;
FIG. 3 is a plan view schematically illustrating a D driving element together with a pixel electrode and the like. FIG. 15B is a cross-sectional view taken along the line BB ′ of FIG.

FIG. 16 is an equivalent circuit diagram showing a liquid crystal element according to a sixth embodiment together with a drive circuit.

FIG. 17 is a partially broken perspective view schematically showing a liquid crystal element according to a sixth embodiment.

FIG. 18 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix forming an image display area of a liquid crystal device according to a seventh embodiment of the present invention.

FIG. 19 is a plan view of a plurality of pixel groups adjacent to each other on a transparent substrate on which data lines, scanning lines, pixel electrodes, and the like are formed in a seventh embodiment.

20 is a sectional view taken along line C-C 'of FIG.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiji Okamoto 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Seki ▲ Taku ▼ Mi 3-5-5 Yamato, Suwa City, Nagano Prefecture No. Seiko Epson Corporation

Claims (18)

[Claims] 1. A reflective display function in which light incident on a liquid crystal layer from one side is reflected by a semi-transmissive reflective layer for display, and light incident on the other side opposite to the one side is semi-transmitted. A transmission type display function of displaying by transmitting through the reflection layer, by changing the voltage applied to the liquid crystal layer,
A first display state, which is a bright display state, and a second display state, which is a dark display state, can be selected. In the second display state, light enters the liquid crystal layer from the one side. A liquid crystal device in which light passes through the liquid crystal layer and is reflected by a semi-transmissive reflection film to become circularly polarized light or elliptically polarized light in a predetermined rotation direction, wherein a first polarizing plate disposed on the one side; An optical element provided on the other side, for converting light incident on the transflective layer from the other side into polarized light in the predetermined rotation direction. 2. The liquid crystal device according to claim 1, wherein in the second display state, light incident on the liquid crystal layer from the one side is reflected by the transflective layer. And an ellipticity when light incident on the liquid crystal layer from the other side is transmitted through the semi-transmissive reflective layer. 3. The liquid crystal device according to claim 1, wherein a voltage applied to the liquid crystal layer is changed.
A liquid crystal device wherein a first display state which is a bright display state, a second display state which is a dark display state, and a third display state which is an intermediate brightness thereof can be selected. 4. The liquid crystal device according to claim 1, wherein, in the second display state, light incident on the liquid crystal layer from the one side is reflected by the transflective film. In the first display state, light incident on the liquid crystal layer from the one side becomes linearly polarized light when reflected by the transflective film in the first display state. Liquid crystal device. 5. The liquid crystal device according to claim 1, wherein the optical element is provided on a second polarizing plate provided on the other side, and between the second polarizing plate and the liquid crystal layer. And a retardation plate. 6. The liquid crystal device according to claim 5, wherein the ellipticity is 0.85 or more when light incident on the liquid crystal layer from the other side passes through the semi-transmissive reflective layer. A transmission axis of the second polarizing plate, an axis of the phase difference plate, and a retardation value. 7. The liquid crystal device according to claim 5, wherein the retardation plate includes a quarter-wave plate. 8. The liquid crystal device according to claim 1, wherein the optical element comprises: a reflective polarizing plate provided on the other side; and a phase difference provided between the reflective polarizing plate and the liquid crystal layer. A liquid crystal device comprising: a plate. 9. The liquid crystal device according to claim 8, wherein the ellipticity is 0.85 or more when light incident on the liquid crystal layer from the other side passes through the semi-transmissive reflective layer. A transmission axis of the reflective polarizing plate, an axis of the retardation plate, and a retardation value. 10. The liquid crystal device according to claim 8, wherein the retardation plate includes a quarter-wave plate. 11. The liquid crystal device according to claim 1, wherein the optical element includes a liquid crystal polymer exhibiting a cholesteric phase. 12. The liquid crystal device according to claim 1, further comprising a lighting device disposed on a side of the optical element different from the liquid crystal layer. 13. A liquid crystal cell having a liquid crystal layer between a first substrate and a second substrate disposed opposite to the first substrate, wherein the liquid crystal cell is disposed on a surface of the second substrate on the liquid crystal layer side, A semi-transmissive reflective layer that reflects and transmits light at a predetermined reflectance and transmittance, a lighting device disposed on a side of the second substrate different from the liquid crystal layer, and a light-emitting device between the liquid crystal cell and the lighting device. The disposed polarizing plate or reflective polarizing plate, and disposed between the polarizing plate or the reflective polarizing plate and the liquid crystal cell, and emitted from the lighting device and passed through the polarizing plate or the reflective polarizing plate to form a straight line. A phase difference plate that converts the polarized light into circularly polarized light or elliptically polarized light, wherein the rotation direction of the polarized light emitted from the illumination device and passing through the phase difference plate, and the first substrate in a dark display state Polarized light incident from the side and reflected by the transflective plate A liquid crystal device, characterized in that the direction of rotation, coincide. 14. The liquid crystal device according to claim 13, wherein the second polarizing plate or the reflection plate emits light from the illumination device and passes through the retardation plate so that the ellipticity is 0.85 or more. A liquid crystal device wherein a transmission axis of a polarizing plate, an axis of the retardation plate, and a retardation value are set. 15. The liquid crystal device according to claim 14, wherein the retardation plate includes at least one quarter-wave plate. 16. A liquid crystal cell having a liquid crystal layer between a first substrate and a second substrate opposed to the first substrate, and a liquid crystal cell disposed on a surface of the second substrate on the liquid crystal layer side, and A semi-transmissive reflective layer that reflects and transmits light at a predetermined reflectance and transmittance; a lighting device disposed on a side of the second substrate different from the liquid crystal layer; and between the liquid crystal cell and the lighting device. Are located in
A selective reflection layer that selectively reflects and transmits circularly polarized light or elliptically polarized light according to the rotation direction thereof, and a rotation direction of circular knitted light or elliptically polarized light emitted from the illumination device and transmitted through the selective reflection layer; A liquid crystal device, wherein a rotation direction of circularly polarized light or elliptically polarized light incident from the first substrate and reflected by the transflective plate coincides with each other in a display state. 17. The liquid crystal device according to claim 11, wherein the selective reflection layer is a selective reflection layer using selective reflection of cholesteric liquid crystal. 18. An electronic device comprising a liquid crystal device as a display portion thereof, wherein the electronic device comprises the liquid crystal device according to claim 1.