JP3472927B2 - Liquid crystal device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the technical field of liquid crystal devices, and more particularly, to the structure of a liquid crystal device capable of switching between reflective display and transmissive display and electronic equipment using the liquid crystal device. Regarding the technical field.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal device has been widely used as a display unit attached to a portable device or a device because of its low power consumption. However, since the display is visible by utilizing external light, There was a problem that the display could not be read in a dark place. For this reason, there is proposed a liquid crystal device of a type in which outside light is utilized in a bright place like a normal reflection type liquid crystal device, but in a dark place a display can be visually recognized by an internal light source.

As disclosed in Japanese Utility Model Application Laid-Open No. 57-049271, a structure in which a polarizing plate, a semi-transmissive reflection plate and a backlight are sequentially arranged on the outer surface of the liquid crystal panel on the side opposite to the observation side is used. is doing. In this liquid crystal device, when the surroundings are bright, external light is taken in to perform reflective display using the light reflected by the semi-transmissive reflector, and when the surroundings become dark, the backlight is turned on and the semi-transmissive reflector is displayed. A transmissive display is performed in which the display can be visually recognized by the light transmitted through.

Another liquid crystal device is disclosed in Japanese Patent Application Laid-Open No. 8-292413, which improves the brightness of a reflective display. This liquid crystal device has a structure in which a semi-transmissive reflection plate, a polarizing plate, and a backlight are sequentially arranged on the outer surface of the liquid crystal panel opposite to the observation side. When the surroundings are bright, external light is taken in and the light reflected by the semi-transmissive reflection plate is used to perform reflective display.When the surroundings become dark, the backlight is turned on and the polarizing plate and the semi-transmission reflection plate are transmitted. A transmissive display is performed in which the display can be visually recognized by the emitted light. With such a configuration, since there is no polarizing plate between the liquid crystal cell and the semi-transmissive reflection plate, a reflection type display brighter than that of the liquid crystal device described above can be obtained.

[0005]

However, in the liquid crystal device described in Japanese Unexamined Patent Publication (Kokai) No. 8-292413, since the transparent substrate is interposed between the liquid crystal layer and the semi-transmissive reflection plate, it is possible to prevent double reflection and display. There is a problem that bleeding occurs.

Further, with the recent development of portable equipment and OA equipment, there is a demand for colorization of liquid crystal displays, and even in equipment using a reflective liquid crystal device, colorization may be required. Many. However, in the method of combining the liquid crystal device and the color filter described in the above publication, since the semi-transmissive reflection plate is arranged behind the liquid crystal panel, it is between the liquid crystal layer or the color filter and the semi-transmission reflection plate. The thick transparent substrate of the liquid crystal panel intervenes, which causes double reflection and display bleeding due to parallax, which makes it impossible to obtain sufficient color development.

In order to solve this problem, Japanese Patent Laid-Open No. 9-2
In Japanese Patent No. 58219, there is proposed a reflective color liquid crystal device in which a reflector is arranged so as to be in contact with the liquid crystal layer. However, in this liquid crystal device, the display cannot be recognized when it becomes dark as is well known.

On the other hand, Japanese Patent Application Laid-Open No. 7-318929 proposes a transflective liquid crystal device in which a pixel electrode also serving as a transflective film is provided on the inner surface of a liquid crystal cell. However, this liquid crystal device uses a semi-transmissive reflective film such as a metal thin film in which fine defects such as hole defects and concave defects and fine apertures are scattered. It is possible to prevent alignment failure of the liquid crystal due to the influence of the electric field, fail to obtain sufficient contrast ratio and brightness, and to prevent coloring due to wavelength dispersion of light in both reflective display and transmissive display. There are many technical problems such as difficulty and white balance prevention in the gap between pixel electrodes or improvement in contrast and improvement in brightness at the time of reflection type display. However, there is a problem that the image cannot be displayed.

Further, a special process is additionally required for the production thereof, and it is difficult to meet the general demand for reduction of the production cost in the technical field concerned.

The present invention has been made in view of the above-mentioned problems, and it is possible to switch between a reflective display and a transmissive display capable of displaying a high-quality image without causing a double reflection due to parallax or a blur of the display. An object of the present invention is to provide a transflective liquid crystal device and an electronic apparatus using the liquid crystal device.

[0011]

The above object of the present invention is to provide a pair of transparent first and second substrates, a liquid crystal layer sandwiched between the first and second substrates, and the second substrate described above. A plurality of reflective electrodes formed on the surface of the liquid crystal layer side with a predetermined gap therebetween, and on the surface of the first substrate on the liquid crystal layer side facing the position of the reflective electrode and the gap of the reflective electrode. A liquid crystal having a transparent electrode formed at a position and an illuminating device arranged on a side of the second substrate opposite to the liquid crystal layer, wherein an area of the reflective electrode is smaller than an area of the transparent electrode. Achieved by the device.

According to the liquid crystal device of the present invention, at the time of reflective display, the reflective electrode reflects the external light incident from the first substrate side to the liquid crystal layer side. At this time, since the reflective electrode is arranged on the liquid crystal layer side of the second substrate, there is almost no gap between the liquid crystal layer and the reflective electrode, and therefore, double image display or display bleeding due to parallax occurs. Does not occur. On the other hand, in the transmissive display, the light source light emitted from the illumination device and incident from the second substrate side is transmitted to the liquid crystal layer side through the gap between the reflective electrodes.

Here, in particular, the liquid crystal can be driven by the oblique electric field generated between the reflective electrode and the transparent electrode portion facing the gap of the reflective electrode. Therefore, in the dark,
By driving the light source light that passes through the gap between the reflective electrodes using an oblique electric field, bright display is possible. at the same time,
It is possible to prevent the liquid crystal portion facing the gap between the reflective electrodes from being driven out and not to be blank, and it is possible to reduce the display defects related to the gap between the reflective electrodes. On the contrary, it is not necessary to cover the gap between the reflective electrodes with a light shielding film generally called a black matrix or a black mask, which is advantageous in terms of device configuration, manufacturing, or design.

As a driving method of the liquid crystal device of the present invention, various known driving methods such as a passive matrix driving method, a TFT active matrix driving method, a TFD active matrix driving method and a segment disturbance method can be adopted. Therefore, the plurality of reflective electrodes may be formed in a line shape or a rectangular shape depending on the driving method adopted.

The width of the gap between the reflective electrodes is 0.01 μm.
m or more and 20 μm or less, particularly 1 μm
It is preferably 5 μm or more. By doing so, it is difficult for human beings to recognize, it is possible to suppress the deterioration of the display quality caused by providing the gap, and it is possible to realize the reflective display and the transmissive display at the same time.

The gap is preferably formed with an area ratio of 5% or more and 30% or less with respect to the reflective electrode. By doing so, it is possible to suppress the decrease in the brightness of the reflective display, and it is possible to realize the transmissive display by the light introduced into the liquid crystal layer through the gap between the reflective electrodes. In particular, even when the liquid crystal portion driven by the oblique electric field occupies a small portion of the entire liquid crystal layer during the transmissive display, by increasing the brightness of the light source by the lighting device, the liquid crystal portion provides a sufficiently bright and high-quality display. It will be possible.

In one aspect of the liquid crystal device of the present invention, a plurality of the reflective electrodes are formed in a longitudinal shape, and the alignment direction of the liquid crystal molecules at the substantially central position between the transparent electrode and the reflective electrode and the reflective electrode. When the angle formed by the longitudinal direction is φ, −
60 ° ≦ φ ≦ 60 °.

According to this aspect, the reflective electrode has a line shape,
Since it is formed in a longitudinal shape such as a rectangle, and the alignment direction of the liquid crystal molecules that is most movable at the approximate center position between the transparent electrode and the reflective electrode and the longitudinal direction of the reflective electrode are separated by 30 ° or more from the orthogonal, The orientation state of liquid crystal molecules is favorably changed by applying a voltage between the transparent electrode and the reflective electrode, with almost no occurrence of tilt domains. Therefore, the threshold voltage when driving the liquid crystal can be lowered, and the power consumption of the liquid crystal device can be reduced.

Further, it becomes possible to eliminate display defects such as disclination due to tilt domains in the liquid crystal layer. If this angle φ is −60 ° ≦ φ ≦
If it is not within the range of 60 °, the alignment direction of the liquid crystal molecules and the longitudinal direction of the reflective electrode are substantially orthogonal to each other, so that the tilt domain is violently generated. As a result, the drive voltage also rises. In particular, the above-mentioned effects are maximized within the range of -30 ° ≤ φ ≤ 30 °.

In another aspect of the liquid crystal device of the present invention, when the angle formed by the alignment direction of the liquid crystal molecules near the reflective electrode and the longitudinal direction of the reflective electrode is Ψ, 30 ° ≦ Ψ ≦ 30 °. . According to this aspect, since the alignment direction of the liquid crystal molecules in the vicinity of the reflective electrode to which a predetermined pretilt angle is applied and the longitudinal direction of the reflective electrode are closer to parallel than orthogonal, the liquid crystal molecules at the substrate interface are affected by the oblique electric field. There is almost no possibility of reverse tilt. Therefore, it is possible to eliminate a display defect such as disclination due to the tilt domain due to the reverse tilt.

As a result, the threshold voltage when driving the liquid crystal can be lowered, and the power consumption of the liquid crystal device can be reduced. If this angle Ψ is outside the range of −30 ° ≦ Ψ ≦ 30 °, the liquid crystal molecules at the substrate interface are significantly tilted reversely due to the influence of the oblique electric field, resulting in a display defect. Furthermore, the driving voltage also increases, and power consumption increases. In particular, in the range of -10 ° ≤ Ψ ≤ 10 °, the above-mentioned effects are maximized.

In another aspect of the liquid crystal device of the present invention, a first polarizing plate disposed on the opposite side of the first substrate from the liquid crystal layer, and disposed between the first substrate and the first polarizing plate. And at least one first retardation plate. According to this aspect, good display control can be performed mainly in the reflective display and the transmissive display by the first polarizing plate, and coloring caused by wavelength dispersion of light is mainly caused by the first retardation plate. The effect on the color tone of can be reduced.

In another aspect of the liquid crystal device of the present invention, a second polarizing plate disposed between the second substrate and the lighting device and a second polarizing plate disposed between the second substrate and the second polarizing plate. And at least one second retardation plate that has been processed. According to this aspect, good display control can be performed mainly in the transmissive display by the second polarizing plate, and the influence on the color tone such as coloring due to the wavelength dispersion of light is mainly reduced by the second retardation plate. be able to.

In another aspect of the liquid crystal device of the present invention, the reflective electrode contains 95% by weight or more of Al and has a layer thickness of 1
It is 0 nm or more and 40 nm or less. According to this aspect, a semi-transmissive reflective type reflective electrode having a thin layer thickness can be formed. According to experiments, a semi-transmissive reflection type reflective electrode having a transmittance of 1% or more and 40% or less and a reflectance of 50% or more and 95% or less can be manufactured in this layer thickness range.

In another aspect of the liquid crystal device of the present invention, a color filter is further provided between the reflective electrode and the first substrate. According to this aspect, it is possible to perform reflective color display by external light and transmissive color display using the illumination device. Color filter is 380nm or more and 780nm
It preferably has a transmittance of 25% or more for all light in the following wavelength ranges. By doing this,
Bright reflective color display and transmissive color display can be realized.

In another aspect of the liquid crystal device of the present invention, a scattering plate is further provided on the side of the first substrate opposite to the liquid crystal layer.

According to this aspect, the specular feeling of the reflecting electrode can be made to appear as a scattering surface (white surface) by the scattering plate.
Further, due to the scattering by the scattering plate, it is possible to display a wide viewing angle. The position of the scattering plate may be any position as long as it is on the side opposite to the liquid crystal layer of the first substrate. Considering the influence of backscattering of the scattering plate (scattering to the incident light side when external light is incident), it is desirable to dispose the polarizing plate between the polarizing plate and the first substrate. Backscattering is scattered light that is not related to the display of the liquid crystal device, and the presence of this backscattering lowers the contrast during reflective display. Polarizer and first
By placing it between the substrate and the substrate, the amount of backscattered light can be halved by the polarizing plate.

In another aspect of the liquid crystal device of the present invention, the reflective electrode has irregularities. According to this aspect, it is possible to eliminate the mirror-like feeling of the reflective electrode by the unevenness and to make it look like a scattering surface (white surface). Further, due to the scattering due to the unevenness, it is possible to display a wide viewing angle. This uneven shape can be formed by using a photosensitive acrylic resin or the like as the base of the reflective electrode, or by roughening the base glass substrate itself with hydrofluoric acid. From the viewpoint of preventing alignment failure of liquid crystal, it is preferable to further form a transparent flattening film on the uneven surface of the reflective electrode to flatten the surface facing the liquid crystal layer (the surface on which the alignment film is formed). .

In another aspect of the liquid crystal device of the present invention, the reflective electrode comprises a laminated body of a reflective layer and a transparent electrode layer. According to this aspect, even if the reflective electrode is not composed of a single film that is both reflective and conductive, the transparent electrode layer has a function of reflecting external light and a function of applying a liquid crystal driving voltage to the transparent electrode layer. If it is provided, the reflective electrode can be obtained.

The above object of the present invention can also be achieved by an electronic apparatus including the above-described liquid crystal device of the present invention. According to the electronic device of the present invention, there is no double reflection due to parallax or blurring of display, and a transflective liquid crystal device or a transflective color liquid crystal capable of switching between reflective display and transmissive display for display. Various electronic devices using the device can be realized.
Such electronic devices can be used in bright and dark places
A high quality display can be realized regardless of the ambient light.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a liquid crystal device according to the present invention will be described based on examples with reference to the drawings. (First Embodiment) A first embodiment of the liquid crystal device according to the present invention will be described with reference to FIGS. FIG. 1 shows the first of the present invention.
It is a schematic longitudinal cross-sectional view showing the structure of the example. 2 to 4
[Fig. 4] is a plan view showing a specific configuration example of a reflective electrode.

Although the first embodiment is basically related to a simple matrix type liquid crystal display device, it can be applied to an active matrix type device, another segment type device and other liquid crystal devices with the same structure. Is possible.

As shown in FIG. 1, in the first embodiment, the liquid crystal layer 3 is a frame-shaped seal member 4 between two transparent substrates 1 and 2.
A liquid crystal cell sealed by is formed. The liquid crystal layer 3 is composed of nematic liquid crystal having a predetermined twist angle. A color filter 5 is formed on the inner surface of the front transparent substrate 1, and the color filter 5 includes R
Colored layers of three colors (red), G (green), and B (blue) are arranged in a predetermined pattern.

A transparent protective film 10 is coated on the surface of the color filter 5, and a plurality of stripe-shaped transparent electrodes 6 are formed on the surface of the protective film 10 by ITO (Indium Tin Oxid).
e) It is formed of a film or the like. An alignment film 9 is formed on the surface of the transparent electrode 6 and is rubbed in a predetermined direction.

On the other hand, on the inner surface of the rear transparent substrate 2, a plurality of stripe-shaped reflective electrodes 107 formed for each colored layer of the color filter 5 are arranged so as to intersect with the transparent electrode 6. In the case of an active matrix type device including a TFD element or a TFT element, each reflective electrode 107 is formed in a rectangular shape and connected to the wiring via the active element. The reflective electrode 107 is made of Cr or Al.
And the like, and the surface thereof is a reflecting surface that reflects light incident from the transparent substrate 1 side. Reflective electrode 10
An alignment film 19 similar to the above is formed on the surface of 7.

A polarizing plate 11 is arranged on the outer surface of the front transparent substrate 1, and the retardation plate 1 is provided between the polarizing plate 11 and the transparent electrode 1.
3 are arranged. Further, behind the liquid crystal cell, a retardation plate 14 is arranged behind the transparent substrate 2, and a polarizing plate 12 is arranged behind this retardation plate 14. Then, behind the polarizing plate 12, a fluorescent tube 15a that emits white light,
Light guide plate 15 having an incident surface along the fluorescent tube 15a
A backlight 15 having a and b is arranged.

The light guide plate 15b is a transparent body such as an acrylic resin plate on which a rough scattering surface is formed on the entire back surface or a scattering printing layer is formed, and the light of the fluorescent tube 15a, which is the light source, is applied to the end surface. It is configured to receive and emit substantially uniform light from the upper surface of FIG. As another backlight, an LED (light emitting diode), an EL (electroluminescence), or the like can be used.

In the first embodiment, the polarizing plate 11 as an example of the first polarizing plate, the retardation plate 13 as an example of the first retardation plate, and the polarizing plate 12 and the second retardation plate as an example of the second polarizing plate. Since the retardation plate 14 as an example is provided, the polarizing plates 11 and 1
Due to 2, good display control can be performed in both reflective display and transmissive display.

Then, the retardation plate 13 reduces the influence on the color tone such as coloring due to the wavelength dispersion of light during the reflection type display (that is, the phase difference plate 13 is used to optimize the display during the reflection type display). Phase retarder 1
4 reduces the influence on the color tone such as coloring due to the wavelength dispersion of light at the time of the transmissive display (that is, the phase difference plate 14 is used to optimize the display at the time of the reflection type display. Under the intended conditions, the retardation plate 14
It is possible to optimize the display during the transmissive display).

The retardation plate 13 and the retardation plate 14 are one in this embodiment, but a plurality of retardation plates may be arranged at their respective positions by color compensation or viewing angle compensation of the liquid crystal cell. Is also possible. If a plurality of one phase difference plates are used, color compensation or visual compensation can be optimized more easily.

As shown in FIG. 1, in the first embodiment, the reflective electrode 107 is constructed to be slightly smaller than the transparent electrode 6. That is, the reflective electrode 107 on the inner surface of the transparent substrate 2 is formed in a smaller area than the transparent electrode 6 on the inner surface of the transparent substrate 1,
The oblique electric field generated between both electrodes is used to drive the liquid crystal layer 3 facing the gap portion 107b where the reflective electrode 107 is not formed (thus, the light from the backlight 15 can be transmitted). .

In the case of an active matrix type device having a TFD element or a TFT element, the reflective electrode is formed in a rectangular shape and connected to the wiring via the active element.

Next, the operation of the first embodiment configured as described above will be described. First, the reflective display will be described. External light is the polarizing plate 11 and the retardation plate 1 in FIG.
3 and the color filter 5, respectively, and after passing through the liquid crystal layer 3, they are reflected by the reflective electrode 107 and again the polarizing plate 1
It is emitted from 1. At this time, the transmission (bright state) and absorption (dark state) of the polarizing plate 11 and the intermediate brightness therebetween are controlled according to the voltage applied to the liquid crystal layer 3.

Next, the transmissive display will be described. The light from the backlight 15 becomes a predetermined polarized light by the polarizing plate 12 and the retardation plate 14, is introduced into the liquid crystal layer 3 through the gap portion 107b where the reflective electrode 107 is not formed, passes through the liquid crystal layer 3, and then passes through the color filter 5 , And the phase difference plate 13 respectively. At this time, the light introduced into the liquid crystal layer 3 is
The liquid crystal layer 3 is driven by an oblique electric field generated by the reflective electrode 107 and the transparent electrode 6 having different sizes. As a result, the transmission (bright state) and absorption (dark state) of the polarizing plate 11 are caused depending on the voltage applied to the liquid crystal layer 3. State) and brightness in between.

According to the above-described embodiment, it is possible to realize a color liquid crystal device capable of switching between reflective display and transmissive display without double reflection or display bleeding.

2 to 4 show specific examples of the structure of the transparent electrode 6 and the reflective electrode 107 which generate the oblique electric field in the first embodiment. First, FIG. 2 shows a configuration example when the present invention is applied to a TFD active matrix liquid crystal device. Scanning lines 202 are formed on the inner surface of the lower substrate, and a TFD element 203 and a reflective electrode 204 are formed corresponding to each dot. A transparent electrode 201 as a data line is formed on the inner surface of the upper substrate.

Particularly, the transparent electrode 201 has a larger area than the reflective electrode 204 in each pixel,
It is also formed in the facing region where 4 is not formed. Therefore, when the liquid crystal drive voltage is applied, the gap portion 205 (the edge portion of the reflective electrode 204) where the reflective electrode 204 is not formed due to the potential difference between the reflective electrode 204 and the transparent electrode 201.
An oblique electric field is generated at. This oblique electric field causes the reflective electrode 2
By driving the liquid crystal in the vicinity of 04, transmissive display becomes possible.

FIG. 3 shows a structural example when the present invention is applied to a simple (passive) matrix type liquid crystal device. A reflective electrode 302 as a data line is formed on the inner surface of the lower substrate. A transparent electrode 3 as a scanning line is formed on the inner surface of the upper electrode.
01 are formed in a stripe shape. In the gap portion 303 which is the gap between the reflective electrodes 302 and the transparent electrode (scanning line) 301 is formed on the upper substrate, when a potential difference occurs between the reflective electrode 302 and the transparent electrode 301, an oblique electric field is generated. Thus, the liquid crystal facing the gap portion 303 is driven, and a transmissive display is possible.

FIG. 4 shows a structural example when the present invention is applied to a TFT active matrix liquid crystal device. A gate line 403 and a signal line 402 are formed on the inner surface of the lower substrate, and a TFT element 404 and a reflective electrode 405 are formed corresponding to each dot. A transparent electrode 401 as a common electrode (counter electrode) is formed on the inner surface of the upper substrate,
The transparent electrode 401 has a larger area for each pixel than the reflective electrode 405, and is also formed in a facing region where the reflective electrode 405 is not formed.

Therefore, the reflective electrode 405 and the transparent electrode 401
The potential difference causes a diagonal electric field to be generated in the gap portion 406 (the edge portion of the reflective electrode 405) where the reflective electrode 405 is not formed. This oblique electric field drives the liquid crystal in the vicinity of the reflective electrode 405 to enable transmissive display. The first
In the embodiment, driving may be performed in a normally black mode, a scattering plate may be provided, and the reflective electrode may be uneven.
When driving in the normally black mode, the black matrix layer may not be provided.

(Second Embodiment) A second embodiment of the liquid crystal device according to the present invention will be described with reference to FIGS. In the second embodiment, attention is paid to the alignment direction of the liquid crystal molecules in the central part of the liquid crystal layer sandwiched between two transparent substrates in the liquid crystal device similar to the first embodiment shown in FIG.

In the second embodiment, first, when the electrode arrangement of FIG. 2 is adopted, as shown in FIG. 2, the longitudinal direction of the reflective electrode 204 (Y direction in FIG. 2) and the central portion between the substrates described above. The angle formed by the alignment direction 206 of the liquid crystal molecules is defined as φ. In the range of −90 ° ≦ φ <−60 ° and 60 ° <φ ≦ 90 °, a display defect (disclination) due to the reverse tilt domain occurs, and a bright and high-quality transmissive display cannot be obtained. . This is because the orientation direction of the liquid crystal molecules in the central portion between the substrates and the longitudinal direction of the reflective electrode are substantially orthogonal to each other, and the tilt domain appears.

Further, in this range, a display defect occurs, so that the threshold voltage at the time of driving the liquid crystal increases. Here, in the table of FIG. 6, the contrast of the reflection type display (that is, the ratio of the reflectance of white display to the reflectance of black display) and the transmission type when the angle φ defined as described above is changed. The display contrast (that is, the ratio of the transmittance during white display to the transmittance during black display) is shown.

In this case, the liquid crystal mode is a left twist of 255 degrees. As can be seen from the table of FIG. 6, the contrast 1 required for high-quality image display by reflective display
In order to obtain 0 or more and the contrast of 5 or more required for high-quality image display by the transmissive display, -6 is required.
The condition is 0 ° ≦ φ ≦ 60 °.

That is, in the range of −60 ° ≦ φ ≦ 60 °,
Display defects such as disclination due to the reverse tilt domain can be eliminated, and bright and high-quality transmissive display can be obtained. Further, since display defects are less likely to occur, the threshold voltage when driving the liquid crystal can be lowered, and the power consumption of the liquid crystal device can be reduced. In particular, in the range of −30 ° ≦ φ ≦ 30 °, the above-described effects are maximized with high quality, and an extremely high contrast image display can be performed.

When the electrode arrangement shown in FIG. 3 is adopted,
As shown in FIG. 3, the angle formed by the longitudinal direction of the reflective electrode 302 (Y direction in FIG. 3) and the alignment direction 304 of the liquid crystal molecules in the central portion between the substrates is defined as φ. -90 ° ≦ φ <
In the range of -60 ° and 60 ° <φ ≦ 90 °, the display defect (disclination) due to the reverse till domain
Occurs, and a bright and high-quality transmissive display cannot be obtained.

This is because the orientation domain of the liquid crystal molecules in the central portion between the substrates and the longitudinal direction of the reflective electrode are substantially orthogonal to each other, so that a tilt domain appears. Also,
In this range, a display defect occurs, so that the threshold voltage when driving the liquid crystal increases. In the range of −60 ° ≦ φ ≦ 60 °, it becomes possible to eliminate display defects such as disclination due to the reverse tilt domain.
A bright and high-quality transmissive display can be obtained.

Further, since display defects are unlikely to occur, the threshold voltage when driving the liquid crystal can be lowered, and the power consumption of the liquid crystal device can be reduced. In particular, the above-mentioned effects are maximized within the range of -30 ° ≤ φ ≤ 30 °.

Further, when the electrode arrangement of FIG. 4 is adopted, as shown in FIG. 4, alignment of liquid crystal molecules in the longitudinal direction of the reflective electrode 405 (Y direction in FIG. 4) and the above-mentioned central portion between the substrates. The angle formed by the direction 407 is defined as φ. -90 ° ≤
In the range of φ <−60 ° and 60 ° <φ ≦ 90 °, a display defect (disclination) due to the reverse tilt domain occurs, and a bright and high-quality transmissive display cannot be obtained.

This is because the orientation domain of the liquid crystal molecules in the central portion between the substrates and the longitudinal direction of the reflective electrode are substantially orthogonal to each other, so that a tilt domain appears. Also,
In this range, a display defect occurs, so that the threshold voltage at the time of driving the liquid crystal increases. In the range of −60 ° ≦ φ ≦ 60 °, it becomes possible to eliminate display defects such as disclination due to the reverse tilt domain.
A bright and high-quality transmissive display can be obtained.

Further, since display defects are unlikely to occur, the threshold voltage when driving the liquid crystal can be lowered, and the power consumption of the liquid crystal device can be reduced. In particular, the above-mentioned effects are maximized within the range of -30 ° ≤ φ ≤ 30 °.

FIG. 5 is a schematic vertical sectional view for explaining the alignment direction of the liquid crystal in the central portion between the substrates. Two boards 50
The liquid crystal 503 has a predetermined twist orientation between the first and the second 502. At this time, the liquid crystal molecules 5 located approximately in the center between the substrates
The molecular long axis direction of 04 is defined as 505. By defining the alignment direction 506 of the liquid crystal molecules near the substrate 502 in FIG. 5, the effect of the present invention described in the second embodiment is
Further, the effect can be secured.

Specifically, the lower substrate (TF
Liquid crystal molecule alignment direction 207 near the D substrate) and the reflection electrode 20.
When the angle formed by the longitudinal direction of 4 is defined as Ψ, −30
A desirable range is ≤ Ψ ≤ 30 °. The reason for this is that in the range other than −30 ° ≦ Ψ ≦ 30 °, the liquid crystal molecules at the substrate interface undergo reverse tilt due to the influence of the oblique electric field, resulting in a display defect.

Here, in the table of FIG. 7, the contrast of the reflection type display when the angle Ψ defined as described above is changed (that is, the ratio of the reflectance of white display to the reflectance of black display). And the contrast of transmissive display (that is, the ratio of transmissivity during white display to transmissivity during black display).

In this case, the liquid crystal mode is left twist of 70 degrees. As can be seen from the table of FIG. 7, the contrast 10 required for high-quality image display by reflection type display
In order to obtain the above and to obtain a contrast of 5 or more required for high-quality image display by the transmissive display, -30
The condition is that ≤ ≤ Ψ ≤ 30 °.

That is, in the range of −30 ° ≦ Ψ ≦ 30 °,
The liquid crystal molecules at the substrate interface hardly reverse tilt under the influence of the oblique electric field, and display defects hardly occur. Similarly, liquid crystal molecule alignment directions 305 and 408 near the lower substrate in FIGS.
It is possible to eliminate display defects such as disclinations due to tilt domains when the angle Ψ formed with the longitudinal direction of 5 is -30 ° or more and 30 ° or less.

As a result, the threshold voltage at the time of driving the liquid crystal can be lowered and the power consumption of the liquid crystal device can be reduced. In particular, in the range of -10 ° ≤ Ψ ≤ 10 °, the above-mentioned effects are maximized. Also in the second embodiment, it may be driven in a normally black mode, a scattering plate may be provided, and the reflection electrode may be uneven. Furthermore, when driving in the normally black mode, the black matrix layer may not be provided.

The colored layer of the color filter 5 used in the first and second embodiments described above will be described with reference to FIG. FIG. 8 is a characteristic diagram showing the transmittance of each colored layer of the color filter 5.

In each of the above embodiments, in the case of performing the reflective display, the incident light once passes through one of the colored layers of the color filter 5, passes through the liquid crystal layer, is reflected by the reflective electrode 107, and is colored again. It is transmitted after passing through the layer. Therefore, unlike a normal transmissive liquid crystal device,
Since the light passes through the color filter 5 twice, the display becomes dark and the contrast deteriorates with the normal color filter.

Therefore, in each embodiment, as shown in FIG. 8, the R, G, and B colored layers of the color filter 5 are light-colored so that the minimum transmittance 61 in the visible region is 25 to 50%. Is forming. The lightening of the colored layer is performed by reducing the film thickness of the colored layer or decreasing the concentration of the pigment or dye mixed in the colored layer. This makes it possible to prevent the display brightness from being lowered when the reflective display is performed.

The lightening of the color filter 5 causes the lightening of the display because it is transmitted through the color filter 5 only once when the transmissive display is performed. However, in each embodiment, the light of the backlight is reflected by the reflection film. It is often convenient to secure the brightness of the display, because many of them are often blocked.

The liquid crystal device of the present invention is not limited to the above-mentioned embodiments, but can be appropriately modified within the scope of the gist or idea of the invention which can be read from the claims and the entire specification. Liquid crystal devices with modifications are also included in the technical scope of the present invention.

[0073]

INDUSTRIAL APPLICABILITY The liquid crystal device according to the present invention can be used as various display devices capable of displaying a bright and high-contrast image, and further can be used as a liquid crystal device constituting a display portion of various electronic devices. Is. Further, the electronic apparatus according to the present invention is a liquid crystal television configured using such a liquid crystal device, a viewfinder type or a monitor direct-viewing type video tape recorder, a car navigation device, an electronic notebook, a calculator, a word processor, a workstation, It can be used as a mobile phone, a videophone, a POS terminal, a touch panel, or the like.

In particular, when the liquid crystal device according to the present invention is used as the display unit of a portable information device, a bright and vivid portable information device can be obtained regardless of whether it is a reflective type, a semi-transmissive reflective type or a transmissive type.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a liquid crystal device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a specific configuration example of a reflective electrode according to the first embodiment of the present invention.

FIG. 3 is a plan view showing another specific configuration example of the reflective electrode according to the first embodiment of the present invention.

FIG. 4 is a plan view showing another specific configuration example of the reflective electrode in the first embodiment of the present invention.

FIG. 5 is a schematic vertical cross-sectional view for explaining the alignment direction of the liquid crystal in the central portion between the substrates of the liquid crystal device according to the present invention.

FIG. 6 is a table showing contrast in reflective display and contrast in transmissive display when the angle φ is changed in the second embodiment of the present invention.

FIG. 7 is a table showing contrast in reflective display and contrast in transmissive display when the angle Ψ is changed in the second embodiment of the present invention.

FIG. 8 is a graph showing the light transmittance of each colored layer of the color filter of each example according to the present invention.

[Explanation of symbols]

1, 2 transparent substrate 3 Liquid crystal layer 4 Seal material 5 color filters 6, 201, 301, 401 Transparent electrode 9, 19 Alignment film 10 Protective film 11, 12 Polarizer 13, 14 Phase plate 15a fluorescent tube 15b Light guide plate 15 backlight 107, 204, 302, 405 Reflective electrode 107b, 205, 303, 406 Gap 202 scan lines 203 TFD element 302 reflective electrode 403 gate line 402 signal line 404 TFT element 501,502 Substrate 503 liquid crystal 504 liquid crystal molecule 505 Molecular long axis direction 506 Alignment direction of liquid crystal molecules near the substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Okumura 3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation (56) Reference JP-A-7-134300 (JP, A) JP-A-6 −313899 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/1343 G02F 1/1335 G02F 1/1362 G02F 1/1333 G02F 1/13357

Claims (11)

(57) [Claims] 1. A pair of transparent first and second substrates, a liquid crystal layer sandwiched between the first and second substrates, and a predetermined gap on a surface of the second substrate on the liquid crystal layer side. a reflective electrode formed in plurality at a, scan which is plurally formed on the surface of the liquid crystal layer side of the first substrate
A stripe-shaped transparent electrode, the second provided with a substrate the liquid crystal layer of the arranged illumination device on the opposite side, the stripe-shaped transparent electrode and a region opposed to the reflective electrode, the reflective electrodes adjacent to each other Is formed in the area facing the gap part of the
A liquid crystal device, wherein a side end portion of the transparent electrode is arranged in the gap portion of the reflection electrode . 2. A plurality of the reflective electrodes are formed in a longitudinal shape, and an angle formed by an alignment direction of liquid crystal molecules at a substantially central position between the transparent electrode and the reflective electrode and a longitudinal direction of the reflective electrode is φ.
The liquid crystal device according to claim 1, wherein -60 ° ≦ φ ≦ 60 °. 3. When the angle formed by the alignment direction of the liquid crystal molecules near the reflection electrode and the longitudinal direction of the reflection electrode is Ψ, -30 ° ≦ Ψ ≦ 30 ° is satisfied. The liquid crystal device according to item 1. 4. A first polarizing plate disposed on the side of the first substrate opposite to the liquid crystal layer, and at least one first phase difference disposed between the first substrate and the first polarizing plate. The liquid crystal device according to claim 1, further comprising a plate. 5. A second polarizing plate arranged between the second substrate and the lighting device, and at least one second phase difference arranged between the second substrate and the second polarizing plate. The liquid crystal device according to claim 1, further comprising a plate. 6. The reflective electrode comprises Al of 95% by weight or more.
The liquid crystal device according to claim 1, further comprising: and having a layer thickness of 10 nm or more and 40 nm or less. 7. Between the reflective electrode and the first substrate,
The color filter is further provided, The color filter according to claim 1,
The liquid crystal device according to item 1. 8. The side of the first substrate opposite to the liquid crystal layer,
The liquid crystal device according to claim 1, further comprising a scattering plate. 9. The liquid crystal device according to claim 1, wherein the reflective electrode has irregularities. 10. The liquid crystal device according to claim 1, wherein the reflective electrode comprises a laminated body of a reflective layer and a transparent electrode layer. 11. An electronic apparatus comprising the liquid crystal device according to claim 1.