JP3480260B2 - Liquid crystal devices and electronic equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to reflectors, and in particular to polarized reflectors. The present invention also relates to a liquid crystal device using this reflector, and more particularly to a reflection type or semi-transmissive reflection type monochrome or color liquid crystal device, and further to electronic equipment equipped with this liquid crystal device.

[0002]

2. Description of the Related Art Reflective liquid crystal devices and semi-transmissive reflective liquid crystal devices with low power consumption are suitable for information tools such as PDAs and portable electronic equipment such as mobile phones and watches. However, the conventional reflective liquid crystal device and the semi-transmissive liquid crystal device have a problem that the display is dark.

One of the reasons why the display is dark is that a reflector used in a conventional liquid crystal device reflects external light mainly in its regular reflection direction. In the regular reflection direction, in addition to the light reflected by the reflector, the light reflected by the liquid crystal cell, the surface of its protective plate, and various interfaces inside the cell are reflected. These reflected lights do not contribute to the display of the liquid crystal cell.
Therefore, although the specular reflection direction is bright, the contrast is low. For this reason, when looking at a reflective or semi-transmissive reflective liquid crystal device, a person unconsciously observes from a direction in which specular reflection is removed. Since sufficient light is not reflected in directions other than specular reflection, the display becomes dark.

As one means for solving such a problem,
A method of reflecting external light in a direction different from regular reflection is disclosed in Japanese Patent Laid-Open No. 61-270731 or SID95 (SID
International Symposium D
igest of Technical Paper
s, Volume XXVI, pp. 176, 199
5).

FIG. 14 is a diagram showing a main part of a structure of a reflection type light modulation device (reflection type liquid crystal device) disclosed in Japanese Patent Laid-Open No. 61-270731. In FIG. 14, 1401
Is a reflection plate and 1402 is a liquid crystal cell. Reflector 1401
Is an aluminum reflector having a saw-like cross section like a diffraction grating. Light from the external light source 1403 1411
Most of the light 1412 enters the liquid crystal cell and is reflected by the reflector 1401 toward the viewer 1404, so that a very bright display can be obtained. On the other hand, some light 14
13 is reflected by the surface of the liquid crystal cell and escapes downward. Since this light does not reach the observer, high contrast is obtained.

The method disclosed in SID95 is based on almost the same idea, but uses a hologram reflection plate as a reflection plate. This reflector also has the feature of reflecting light in a direction different from regular reflection. The hologram reflector is commercially available from Polaroid as IMAGIX (trade name) and is generally available.

[0007]

However, such a conventional reflector also has a problem.

It is technically difficult for the reflector disclosed in Japanese Patent Application Laid-Open No. 61-270731 to form a saw-like diffraction grating into an invisible fine pattern. In addition, even if fine processing is possible, there is a risk of interfering with the dot matrix type liquid crystal device and causing a moire phenomenon. In addition, interference color generation due to diffraction will also be a problem.

The reflector disclosed in SID95 also has the problem of interference color. The conventional hologram reflector is a monochromatic reflector such as green, and a technique for making it a white reflector has not been established yet. Therefore, its use is extremely limited.

Therefore, an object of the present invention is to provide a reflector that reflects a large amount of external light in a direction different from specular reflection. Of course, the external light in this case is not limited to light of a specific wavelength. It is another object of the present invention to provide a liquid crystal device which is bright and has high contrast and less reflection of external light, and in particular, a reflective or semi-transmissive reflective monochrome or color liquid crystal device. Another object of the present invention is to provide an electronic device with low power consumption.

[0011]

A liquid crystal device according to the present invention comprises a liquid crystal cell having a liquid crystal layer sandwiched between an upper substrate and a lower substrate,
In a liquid crystal device having a light reflection plate provided on the lower substrate side and a light control plate provided between the liquid crystal layer and the light reflection plate, the light control plate is incident at a predetermined angle. The light control plate is configured to selectively scatter light and transmit light incident at an angle other than the predetermined angle, and the light control plate has a direction in which the light incident at the predetermined angle is selectively scattered. Is arranged in the liquid crystal cell such that the direction of the scattering axis projected on the liquid crystal cell is in the direction of approximately 6 o'clock in the plane of the liquid crystal cell.

The expression "what time direction" refers to the direction in the plane of the liquid crystal device with the numbers on the dial assuming that the clock face is superposed on the liquid crystal device. 12
The time direction, the 3 o'clock direction, the 6 o'clock direction, and the 9 o'clock direction correspond to the upward direction, the right direction, the downward direction, and the left direction of the liquid crystal device, respectively. With such a configuration, the liquid crystal device of the present invention can reflect a large amount of external light in a direction different from the specular reflection direction, and efficiently reflect the light incident from the 12:00 o'clock direction toward the observer to provide a bright display. Can be obtained.

Further, the liquid crystal device of the present invention includes a liquid crystal cell having a liquid crystal layer sandwiched between an upper substrate and a lower substrate, a light reflecting plate provided on the lower substrate side, the liquid crystal layer and the optical substrate. In a liquid crystal device having at least two light control plates provided between a reflection plate and each of the light control plates, each of the light control plates selectively scatters light incident at a predetermined angle to generate an angle other than the predetermined angle. It is characterized in that the light incident on is transmitted.

Further, in the liquid crystal device of the present invention, the at least two light control plates each have a scattering axis direction in which a direction for selectively scattering the light incident at the predetermined angle is projected on the surface of the light control plate. And the directions of the respective scattering axes are different from each other. It is preferable to stack two light control plates so that the scattering axes are orthogonal or antiparallel. With this configuration, it is possible to reflect external light, which has entered from various directions, in a direction different from the regular reflection direction more than before.

Further, in the liquid crystal device of the present invention, the light control plate has a scattering axis direction in which a direction of selectively scattering incident light is projected on the surface of the light control plate, and the predetermined angle is at least the above-mentioned. 1 in the direction of the scattering axis from the normal direction of the light control plate
It is characterized in that the angle is inclined from 0 degree to 20 degrees.
More preferably, it is characterized by scattering light incident from a direction inclined at least 0 to 30 degrees. If there is no scattering in this range and there is scattering at an angle smaller or larger than this, it is impossible to reflect outside light in a normal environment in a direction close to the normal line. The scattering axis refers to the direction in which the scattering direction is projected on the surface of the light control plate, as will be defined later. Also, scattering light means
A haze of 30% or more. With this configuration, it is possible to efficiently reflect the external light that is incident from the direction opposite to the scattering axis direction in the normal direction.

The light control plate is characterized in that a plurality of layers having different refractive indexes are laminated in a direction inclined with respect to the surface of the light control plate. Although this shape itself is similar to a Lippmann hologram, the light control plate used in the present invention is characterized in that the layer pitch is equal to or more than the wavelength of visible light in order to avoid the interference color like the Lippmann hologram. With this configuration, the external light can be reflected in a direction different from that of the regular reflection more than in the conventional case by reflection and refraction at the layer interface.

In the liquid crystal device of the present invention, the light control plate is formed by laminating a plurality of layers having different refractive indexes in a direction inclined with respect to the surface of the light control plate. The layer is inclined by an angle of 5 degrees or more and 20 degrees or less on average from the normal direction of the surface of the light control plate. More preferably, it is desirable that the layers are inclined at an angle of 10 degrees or more and 15 degrees or less on average from the normal line direction of the plate surface. When the inclination angle is smaller than 5 degrees, the outgoing angle of the reflected light is close to the incident angle from the light source, and the effect is produced only in the arrangement in which the light source is in the shadow of the observer. On the other hand, if the inclination angle is greater than 20 degrees, the light that has entered the surface of the reflector is not emitted in the normal direction. With this configuration, it is possible to reflect external light in a normal environment in a direction different from that of regular reflection more than in the conventional case.

Further, in the liquid crystal device of the present invention, the light reflection plate is a reflection type polarizing plate having a transmission axis for transmitting or reflecting incident light and a reflection axis, and the back surface of the reflection type polarizing plate absorbs light. A plate or a semi-light absorbing plate is arranged. And more preferably, it is desirable to provide a light absorbing plate or a semi-light absorbing plate on the side opposite to the light control plate with the reflective polarizing plate interposed therebetween. With this configuration, it is possible to reflect a certain linearly polarized light component of the external light in a direction different from the regular reflection direction as compared with the conventional case.

When an absorption type polarizing plate which absorbs light of a predetermined linearly polarized light component is further provided, it is desirable to dispose the absorption type polarizing plate at a position adjacent to the light control plate. According to this structure, a certain linearly polarized light component of the external light can be reflected in a direction different from the regular reflection direction more than in the conventional case.

Further, the liquid crystal device of the present invention is characterized by further comprising a light scattering plate. The light scattering plate is preferably arranged at a position adjacent to the light control plate or the absorption type polarizing plate. With this configuration, it is possible to reflect the external light in a direction different from the regular reflection direction more than before, and to reflect the light in the observer direction regardless of the arrangement of the external light.

Further, when the front light is further provided, the display can be seen even in the dark. The front light is an auxiliary lighting device including a light source and a light guide plate. The new surface reflection generated by the front light does not impair the visibility of the display because the direction is the regular reflection direction. Further, as a property of the front light, light tends to enter the liquid crystal device from a shallow angle, but such light can also be efficiently reflected in the normal direction.

An electronic apparatus according to the present invention includes the above liquid crystal device as a display section.

Further, in the above electronic equipment, when the transparent protective plate is provided on the front surface of the liquid crystal device, the liquid crystal device can be protected without damaging the display.

Further, in the above electronic apparatus, when the tablet device is provided in front of the liquid crystal device,
In addition to low power consumption, a bright and easy-to-see display can be obtained. The tablet device is a transparent position detecting device for handwriting input. A resistance film type tablet device is often used, but this device causes reflection of external light due to a high refractive index resistance film. Even in such a case, clear display can be performed using the reflector of the present invention.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a main part of a structure of a reflector according to Embodiment 1. As shown in FIG. First, the configuration will be described. In FIG. 1, 101 is a light control plate and 102 is a light reflection plate. 101 and 102
Are optically bonded to each other. Optically bonding means using a transparent adhesive having a refractive index close to that of each element, or by heat-sealing without using an adhesive to prevent extra surface reflection. It is to glue.

The light control plate 101 has a property of selectively scattering only incident light within a predetermined angle range and transmitting incident light of other angles. As such a light control plate, there are JP-A-63-309902, JP-A-64-
The light control plates disclosed in JP-A-77001, JP-A-3-107901, JP-A-7-64069 and the like can be used. This light control plate is sold by Sumitomo Chemical Co., Ltd. as Lumisty (trade name) and is generally available.

The light control plate will be described in detail with reference to the drawings. 2A is a sectional view of the light control plate.
(B) is a plan view (view from above) of the light control plate. The light control plate 201 has a laminated structure of a transparent layer 202 having a high refractive index and a transparent layer 203 having a low refractive index. 202 and 2
The layer pitch of 03 (sum of layer thicknesses of 202 and 203) is 2 to 3 μm, and the difference in refractive index between both layers is 0.01 to 0.0.
It is 5. These layers are inclined at an angle 206 on average from the normal direction of the surface of the light control plate. The angle 206 is 5 to 20 degrees. The thickness of the entire light control plate is 100 to 2
It is 00 μm. The structure is similar to that of a Lippmann hologram that stereoscopically records interference fringes, but since the layer pitch is larger than the wavelength of visible light, the interference color peculiar to the hologram does not occur.

FIG. 2 is of course a schematic diagram, and actually does not have such a regular structure. The layer thickness and tilt angle vary irregularly, and the layer structure itself may be lost near the surface of the light control plate. However, because of having such a layered structure on average, the light 204 incident from a relatively high angle with respect to the layer interface.
And has a property of scattering the light 205 incident from a low angle. Here, in the plane perpendicular to both the layer interface and the surface of the light control plate (that is, the paper surface of FIG. 2A), the direction in which the light incident from the back of the light control plate is most scattered is defined as The direction projected on the screen is defined as the scattering axis direction, and the arrow 20
I will show it as 7. In FIG. 1, the hatching applied to the light control plate 101 indicates the layer structure described above.

Next, the light reflection plate 102 of FIG. 1 will be described. As the light reflection plate 102, a mirror surface film in which an aluminum thin film is formed on the surface of a polymer film by a sputtering method or a vapor deposition method is suitable. Of course, a polymer plate or a glass plate may be used instead of the polymer film, and silver may be used instead of aluminum. Further, the surface of the polymer film may be embossed to cause diffuse reflection. Further, it may be a semi-transmissive reflector in which mica is dispersed in a polymer. On the other hand, a material such as a MgO standard white plate or paper that is too strongly scattered is not suitable.

This reflector has a light source 1 obliquely present.
The light 111 incident from 03 is transmitted through the light control plate 101 almost as it is and reflected by the light reflection plate 102. The reflected light travels in the regular reflection direction 113 (angle 114 = angle 115), but at that time, the light is scattered by the light control plate and the normal direction 11
Most of them also go out to 2. Although this reflector is used for various display purposes, since the observer 104 often sees from the direction of the normal line or about 10 degrees before and after the normal line, such a characteristic of the reflector has an effect of making the display bright. There is.

FIG. 3 shows the incident angle 114 of the light in FIG.
The angle dependence of the reflected light intensity when fixed at a fixed angle is shown.
The emission angle of light on the horizontal axis is represented by an inclination angle from the normal direction, as in 115 of FIG. In addition, as the light control plate of the reflector,
Sumitomo Chemical Co., Ltd. Lumisty LCY-005
0 (trade name) was used. The light control plate has an angle 206 in FIG. 2 of about 15 degrees, and scatters light incident from a direction inclined from the normal direction to the scattering axis direction by 0 to 50 degrees. An aluminum mirror surface was used as the light reflection plate. Figure 3
In, the reflected light intensity is largest at 30 degrees in the regular reflection direction, but there is also a small peak in the 3 degree direction close to the normal direction. Such a peak can never be obtained with a simple scattering plate. Like the reflector of the present invention, reflection and refraction at the layer interface occur only by having a layer structure,
Peak occurs. Thanks to this peak, more light is returned to the observer direction and the display becomes brighter.

(Embodiment 2) In the reflector of Embodiment 1, when the reflector is a mirror surface, light is reflected only in a limited direction because scattering occurs only in the light control plate. If the positional relationship among the illumination, the reflector, and the observer is fixed, this may be sufficient, but if not so, it is preferable to provide a scattering means separately.

FIG. 4A is a diagram showing a main part of the structure of the reflector according to the second embodiment of the present invention. First, the configuration will be described. In FIG. 4A, 401 is a light control plate, 402 is a light scattering plate, and 403 is a light reflecting plate. 401 and 402,
402 and 403 are optically bonded to each other. The hatching of the light control plate 401 shows the layer structure. As the light control plate 401 and the light reflection plate 403, the same ones as those used in the first embodiment can be used.

As the light scattering plate 402, a plastic plate in which minute beads are dispersed in binders having different refractive indexes is suitable. Further, similar beads may be mixed in the adhesive to directly bond the light control plate and the light reflection plate.

Light 411 incident on this reflector from a light source 404 in an oblique direction passes through the light control plate 401 almost as it is, is scattered by the light scattering plate 402, and is reflected by the light reflecting plate 403. The reflected light is scattered by the light scattering plate 402 again. Since the scattering of the light scattering plate is not so large, most of the light still goes in the regular reflection direction 413, but a part of the light is emitted in the normal direction 412 by the light control plate 401 and reaches the observer 405.

The reflector of the second embodiment can see a bright display from various directions 414 and 415 due to the light scattering plate. The light also reaches the observer from different positions, especially from the light sources in the lateral direction (front or back of the paper). Therefore, when displaying with this reflector, there is little dependency on the illumination environment and a display with a wide viewing angle can be obtained.

FIG. 4B is a diagram showing the main part of another structure of the reflector according to the second embodiment of the present invention. First, the configuration will be described. In FIG. 4B, 402 is a light scattering plate,
Reference numeral 401 is a light control plate and 403 light reflection plate. 402 and 4
01, 401 and 403 are optically bonded to each other. The hatching of the light control plate 401 shows the layer structure. As the light control plate 401 and the light reflection plate 403, the same ones as described in the first embodiment can be used. The light scattering plate 402 may be a plastic plate in which minute beads are dispersed in binders having different refractive indexes, but an embossed plastic plate can also be used.

This reflector also has almost the same function as the reflector of FIG. 4A, and it can be seen that the position of the light scattering plate does not affect the characteristics. Therefore, one of the structures may be selected in consideration of the manufacturing difficulty.

(Embodiment 3) FIG. 5 is a diagram showing a main part of the structure of a reflector according to Embodiment 3 of the present invention. First, the configuration will be described. In FIG. 5, 5
Reference numeral 01 is a light control plate, 502 is a reflective polarizing plate, and 503 is a light absorption plate. 501 and 502 are optically bonded to each other. The hatching of the light control plate 501 indicates its layer structure. The same light control plate 501 as that used in the first embodiment can be used.

For the light absorbing plate 503, a black vinyl sheet or black paper is used, or a black paint is directly applied and used. In addition to black, if it is a relatively dark color, blue, brown, or gray can be used as desired. In addition, when placing a light behind the reflector to display a transflective display,
The light absorbing plate is replaced with a semi-light absorbing plate having a transmittance of 10% to 80% for visible light. As the semi-light absorbing plate, for example, a light scattering film D202 (trade name) manufactured by Tsujimoto Electric Co., Ltd. is suitable.

The reflective polarizing plate 502 has a property of reflecting light of a predetermined linearly polarized light component and reflecting other light. As such a reflective polarizing plate, a method using a birefringent dielectric multilayer film is disclosed in an internationally published international application (International application number: WO97 / 01788) and Japanese Patent Publication No. 9-506985. Is disclosed in. Further, such a reflective polarizing plate is commercially available as DBEF (trade name) from 3M Company in the United States and is generally available.

Next, the structure of the reflective polarizing plate 502 will be described. FIG. 6 is a diagram illustrating a main part of the structure of the reflective polarizing plate. The reflective polarizing plate is basically a birefringent dielectric multilayer film, and is formed by alternately stacking two kinds of polymer layers 601 and 602. The two types of polymers are selected from materials with high photoelasticity and materials with low photoelasticity. At this time, be careful that the ordinary rays of both have the same refractive index. . For example, PEN (2,6-polyethylene naphthalate) is selected as the material having a large photoelasticity, and coPEN (70-naphthalate / 30-terephthalate copolyester) is selected as the material having a small photoelasticity. Both films are laminated alternately, and the orthogonal coordinate system 60 of FIG.
When stretched about 5 times in the x-axis direction of 3, the refractive index in the x-axis direction was 1.88 in the PEN layer and 1.64 in the coPEN layer. The refractive index in the y-axis direction was about 1.64 for both the PEN layer and the coPEN layer. When light is incident on the laminated film from the normal direction, the light component vibrating in the y-axis direction is transmitted through the film as it is. This is the transmission axis. On the other hand, the component of light oscillating in the x-axis direction is P
The EN layer and the coPEN layer are reflected only when certain conditions are satisfied. This is the reflection axis. The condition is that the optical path length of the PEN layer (product of refractive index and film thickness) and co
That is, the sum of the optical path lengths (the product of the refractive index and the film thickness) of the PEN layer is equal to one half of the wavelength of light. If such PEN layers and coPEN layers are stacked in layers of several tens or more, preferably 100 or more, and having a thickness of 30 μm, almost all of the components of light oscillating in the x-axis direction can be reflected.

The reflection type polarizing plate produced in this way produces a polarization ability only with light of a designed single wavelength. Therefore, by stacking a plurality of reflective polarizing plates having different design wavelengths with their axes aligned, it is possible to provide the polarizing ability in a wide wavelength region.

This reflection type polarizing plate is compared with a normal absorption type polarizing plate + a reflection polarizing means having an aluminum reflecting plate,
Brighter than 30%. There are two reasons. One is that the reflectance of metallic aluminum is less than 90%, while this reflective polarizing plate reflects almost 100% of a predetermined linearly polarized light. Another reason is that a normal absorption type polarizing plate uses a dichroic material such as a halogen substance such as iodine or a dye, and its dichroic ratio is not necessarily high. It is a waste.

In addition to the birefringent dielectric multilayer film as described above, a liquid crystal polymer exhibiting a cholesteric phase can be used as the reflective polarizing plate. This has the function of reflecting a predetermined circularly polarized light component and transmitting the other polarized light components. When this is combined with a quarter-wave plate, it has the function of reflecting a predetermined linearly polarized light component and transmitting the other polarized light components. Details of such a reflective polarizing plate are disclosed in JP-A-8-271837. In addition, such a reflective polarizing plate is a German-made country.
It is sold by Rck under the name TransMax (trade name) and is generally available.

The light 511 incident on the reflector described above from the light source 504 that is present in an oblique direction receives the light control plate 501.
Is transmitted as it is, a predetermined linearly polarized light component is reflected by the reflection type polarizing plate 502, and the remaining light is absorbed by the light absorbing plate 503. The reflected linearly polarized light component has a regular reflection direction 513.
It goes toward (angle 514 = angle 515), but at that time, it is scattered by the light control plate 501, and a large amount is emitted also in the normal direction 512. Since the observer 505 often sees from the normal direction or about 10 degrees before and after the normal direction, such a characteristic of the reflector has an effect of making the display bright.

(Embodiment 4) In the reflector of Embodiment 3, since the reflection of the reflection type polarizing plate 502 is specular, scattering occurs only at the light control plate 501,
Light is reflected only in a limited direction. If the positional relationship among the illumination, the reflector, and the observer is fixed, this may be sufficient, but if not so, it is preferable to provide a scattering means separately.

FIG. 7A is a diagram showing a main part of the structure of the reflector according to the fourth embodiment of the present invention. First, the configuration will be described. In FIG. 7A, 701 is a light control plate, 702 is a light scattering plate, 703 is a reflective polarizing plate, and 704 is a light absorbing plate. 701 and 702 and 702 and 703 are optically bonded to each other. The hatching of the light control plate 701 shows the layer structure. As the light control plate 701, the reflective polarizing plate 703, and the light absorption plate 704, the same ones as those used in the third embodiment can be used.

As the light scattering plate 702, the same one as described in the second embodiment can be used, but care must be taken so as not to cancel the linearly polarized light separated by the reflection type polarizing plate. Specifically, it is important that the diameter of the beads to be dispersed is not made too small, and the beads are not dispersed at such a high density as to cause multiple scattering or made too thick.

Light 711 incident on this reflector from an oblique light source 705 is transmitted through the light control plate 701 almost as it is and scattered by the light scattering plate 702, and a predetermined linearly polarized light component is reflected by the reflection type polarizing plate 703. The remaining light that is reflected is absorbed by the light absorption plate 704. The reflected linearly polarized light component is again scattered by the light scattering plate 702. Since the scattering of the light scattering plate is not so large, most of the light still remains in the specular reflection direction 71.
3 (angle 714 = angle 715), but the light control plate 7
By 01, a part of light is emitted in the normal direction 712 and reaches the observer 706.

The reflector of the fourth embodiment can see a bright display not only in 712 and 713 but also in various directions because of the light scattering plate. The light also reaches the observer from different positions, especially from the light sources in the lateral direction (front or back of the paper). Therefore, when displaying with this reflector,
A display with a wide viewing angle can be obtained with little dependency on the lighting environment.

FIG. 7B is a diagram showing the main part of another structure of the reflector according to the fourth embodiment of the present invention. First, the configuration will be described. In FIG. 7B, 702 is a light scattering plate,
Reference numeral 701 is a light control plate, 703 is a reflective polarizing plate, and 704 is a light absorption plate. 702 and 701 and 701 and 703 are optically bonded to each other. Light control plate 701
The hatching indicates the layer structure. Light control board 7
01, the light-scattering plate 702, the reflective polarizing plate 703, and the light-absorbing plate 704 can be the same as those in FIG. 7A, and the only difference is the stacking order.

This reflector also has substantially the same function as the reflector shown in FIG. 7A, and it can be seen that the position of the light scattering plate does not affect the characteristics. Therefore, one of the structures may be selected in consideration of the manufacturing difficulty.

A curve 801 in FIG. 8 shows the angle dependence of the reflected light intensity when the incident angle 714 of the light in FIG. 7 is fixed at 30 degrees. The emission angle of light on the horizontal axis is represented by an inclination angle from the normal direction, as in 715 of FIG. As a light control plate for the reflector, Lumisty L manufactured by Sumitomo Chemical Co., Ltd.
CY-0050 (trade name) was used. This light control plate has an angle 206 in FIG. 2 of about 15 degrees, and scatters light incident from a direction inclined from the normal direction to the scattering axis direction by 0 to 50 degrees (that is, haze is 30% or more). . As the reflective polarizing plate, DBEF (trade name) manufactured by 3M Company of the United States was used. In the curve 801 of FIG. 8, the reflected light intensity is largest at 30 degrees in the regular reflection direction, but there is also a small peak in the 3 degree direction close to the normal direction. Such a peak can never be obtained with a simple scattering plate.

A curve 802 in FIG. 8 shows the angle dependence of the intensity of reflected light in the same manner for the reflector having the structure shown in FIG. 7A except for the light control plate 701. The reflected light intensity is still highest at 30 degrees in the regular reflection direction, but no peak appears in other directions. Comparing the brightness of both in the normal direction, the intensity of 801 using the light control plate is 3.4.
5. The intensity of 802 without using the light control plate is 0.90 (both are arbitrary units). It can be seen that by arranging the light control plate, the brightness in the normal direction is increased by about 3.8 times. Such an effect is produced only by the layered structure of the light control plate. Reflection and refraction at the layer interface selectively reflect light in directions other than the specular reflection direction.

(Embodiment 5) FIG. 9A is a diagram showing a main part of the structure of a reflector according to Embodiment 5 of the present invention. First, the configuration will be described. In FIG. 9, 901 is a light control plate, 902 is an absorption type polarizing plate, and 903.
Is a light reflector. 901 and 902, 902 and 903
Are optically bonded to each other. The hatching of the light control plate 901 shows the layer structure. Light control plate 90
1. As the light reflection plate 903, the same one as that used in the first embodiment can be used.

The absorption type polarizing plate 902 has a property of absorbing light of a predetermined linearly polarized component and transmitting other light. This is the most commonly used type of polarizing plate at present, and is manufactured by adsorbing a halogen substance such as iodine or a dichroic dye on a polymer film.

Light 911 incident on the reflector described above from a light source 904 that exists in an oblique direction is reflected by a light control plate 901.
Is transmitted almost as it is, a predetermined linearly polarized light component is absorbed by the absorption type polarizing plate 902, and the remaining light is reflected by the light reflection plate 903. The reflected light is the absorption type polarizing plate 902 for the second time.
Through the regular reflection direction 913 (angle 914 = angle 91
Go to 5). At that time, the light is scattered by the light control plate 901 and is also emitted in a large amount in the normal direction 912. Since the observer 905 often sees from the normal direction or about 10 degrees before and after the normal direction, such a characteristic of the reflector has an effect of making the display bright.

Even if the position of the light control plate 901 is between the absorption type polarizing plate 902 and the light reflection plate 903 as shown in FIG. 9B, the effect is the same.

The reflector of the fifth embodiment can also be provided with the light scattering means as in the second and third embodiments. The position may be anywhere on the light reflection plate 903. When such a reflector is used for display, display with a wide viewing angle can be obtained with little dependency on the illumination environment.

(Embodiment 6) FIG. 10 is a diagram showing a main part of a structure of a reflector according to Embodiment 6 of the present invention. FIG. 10A is a sectional view.
(B) is a plan view (view from above). First, the configuration will be described. In FIG. 10A, 1001 and 1002 are light control plates, 1003 is a light scattering plate, 1004 is a reflective polarizing plate, and 1005 is a light absorbing plate. 1001 and 1002,
1002 and 1003, 1003 and 1004 are optically adhered to each other. The hatching of the light control plates 1001 and 1002 shows the layer structure. Light control plate 10
01 and 1002, a light scattering plate 1003, a reflection type polarizing plate 10
04, the light absorption plate 1005 may be the same as that used in the first to fifth embodiments.

In FIG. 10B, 1006 is a reflector, 1011 is a scattering axis of the light control plate 1001, and 1012 is a scattering axis of the light control plate 1002. The definition of the scattering axis is as described in FIG. The two scattering axes are orthogonal.

By superimposing two light control plates with their scattering axes orthogonal to each other, it is possible for the observer to have a sufficient position regardless of whether the position of the light source is 12 o'clock, 3 o'clock or 9 o'clock. It can reflect various light. As the overlapping direction of the two light control plates, antiparallel, 45 degrees, etc. are suitable in addition to the orthogonal directions, and they may be appropriately determined depending on the assumed illumination direction. Also, three or more light control plates may be stacked. However, it is desirable that at least one scattering axis is at 6 o'clock. This is because there are often light sources in the 12 o'clock direction.

(Embodiment 7) The reflector of the present invention can be used in various devices, but the most suitable usage is a display device. For example, by disposing a transparent positive type color film on the front surface of the reflector of the first or second embodiment, a still image can be displayed without a special light source. The reflectors of the first and second embodiments are also suitable for light-receiving display devices such as electrochromic displays and GH-type liquid crystal devices. On the other hand, since the reflectors of Examples 3 to 6 are polarization reflectors, the TN type or S type that uses polarized light is used.
Suitable for TN type liquid crystal device. An example in which the reflector of the present invention is used in an STN type liquid crystal device will be described below.

FIG. 11 is a diagram showing a main part of a structure of a liquid crystal device according to a seventh embodiment of the present invention. FIG. 11A is a sectional view,
FIG. 11B is a plan view (view from above). First, the configuration will be described. In FIG. 11A, 1101 is an absorption type polarizing plate, 1102 is a retardation film, 1103 is an upper glass substrate, 1104 is a transparent electrode, 1105 is a liquid crystal layer,
1106 is a seal part, 1107 is a lower glass substrate, 11
Reference numeral 08 is a light control plate, 1109 is a light scattering plate, 1110 is a reflective polarizing plate, and 1111 is a light absorbing plate. 1101 and 11
02, 1102 and 1103, 1107 and 1108, 11
08 and 1109, 1109 and 1110 are optically bonded to each other. The upper and lower transparent electrodes 1104
However, this is for the sake of clarity in the drawing, and actually they are opposed to each other with a narrow gap of several μm to several tens of μm being maintained. In addition to the illustrated components, components such as a liquid crystal alignment film, an insulating film, a spacer / ball, a driver IC, and a drive circuit are indispensable, but these are not particularly necessary for explaining the present invention, and are rather illustrated. It has been omitted because it may complicate and make it difficult to understand.

Next, each component will be described in order. The absorption type polarizing plate 1101 has a function of absorbing a predetermined linearly polarized light component and transmitting other polarized light components.

The retardation film 1102 is made of, for example, poly.
A uniaxially stretched film of a carbonate resin, which is STN
It is used for compensating the coloring of the display of the liquid crystal device.
It is often omitted in the case of a TN type liquid crystal device.

The liquid crystal layer 1105 comprises a STN nematic liquid crystal composition twisted by 180 to 270 degrees. When the display capacity is small, a 90 ° twisted TN liquid crystal composition may be used. The twist angle is determined by the direction of the alignment treatment on the upper and lower glass substrate surfaces and the amount of the chiral agent added to the liquid crystal.

The laminated body of the light control plate 1108, the light scattering plate 1109, the reflection type polarizing plate 1110, and the light absorption plate 1111 is a reflector, which has been described in the third embodiment, the fourth embodiment, or the sixth embodiment. I used a reflector.

Further, in FIG. 11B, 1112 is the liquid crystal device, and 1121 is the direction of the scattering axis of the light control plate 1108. The light control plate was arranged so that the scattering axis was at 6 o'clock.

The liquid crystal device manufactured as described above is characterized by being extremely bright as compared with the liquid crystal device using the conventional reflector. In particular, when there is a light source in the 12:00 o'clock direction and this is observed from the normal direction of the liquid crystal device, the light source is 4 times brighter than the conventional one. In addition, no matter where the light source is located, it was not darker than before.

The surface of the absorptive polarizing plate 1101 and the interface between the transparent electrode 1104 and the glass are easy to reflect light, and the reflection is a concern. Therefore, conventionally, the surface of the absorption type polarizing plate has been subjected to anti-glare treatment such as anti-reflection and anti-glare. However, in the liquid crystal device of the present invention, even if the anti-glare treatment is not performed, unnecessary reflected light travels in the regular reflection direction and therefore does not reach the observer, and the contrast is not impaired.

Although the embodiments of the reflective liquid crystal device have been described above, a semi-transmissive reflective liquid crystal device can be obtained by using the light absorbing plate 1111 as a semi-light absorbing plate and arranging a backlight behind. Even in the case of a semi-transmissive reflection type liquid crystal device, the effect of the present invention does not change.

As the reflector, the reflector of Example 3 or 4 or 6 using the reflection type polarizing plate is used, but the reflector of Example 5 using the absorption type polarizing plate is also used. good.

Conventionally, in the reflection type color liquid crystal device of the type as in Japanese Patent Application No. 7-180481 in which a micro color filter is arranged for each dot, the darkness of the display has been a big problem. If the reflector of the present invention is used for various liquid crystal devices, bright display is possible. In addition, since a color filter with higher color purity can be used, vivid color display can be performed.

Further, the reflector may be provided between the pair of substrates. In this case, the reflector of Example 1 is used. For example, absorption type polarizing plate, retardation film (optional), upper glass substrate, color filter (optional), transparent electrode, liquid crystal layer, transparent electrode (optional), light control plate, light reflection plate, lower glass The substrates are stacked in this order. With this configuration, only one polarizing plate can be used, but if a liquid crystal display mode as disclosed in Japanese Patent Application Laid-Open No. 3-223715 is adopted, high-quality display is possible. According to this structure, since there is no parallax due to the lower glass substrate, it is possible to display without a shadow. Particularly in the case of a reflective color liquid crystal device, bright display with high color purity can be achieved.

(Example 8) Example 8 Example 8 relates to a liquid crystal device according to Example 8 of the present invention.

The main body of the liquid crystal device is the same as that of the liquid crystal device of the seventh embodiment shown in FIG. A front light as disclosed in JP-A-6-324331 is arranged on the front surface of the liquid crystal device. The front light is an auxiliary lighting device including a light source and a light guide plate. With this configuration, it is possible to see the display of this liquid crystal device even in the dark. The new surface reflection caused by the front light,
Since the reflector of the present invention reflects more light in a direction different from specular reflection than in the conventional case, the visibility of the display is not impaired. Further, as a property of the front light, light tends to enter the liquid crystal device from a shallow angle, but such light can also be efficiently reflected near the front.

(Example 9) Three examples of the electronic device according to the ninth embodiment of the present invention will be shown.

The liquid crystal device of the present invention is suitable for portable equipment which is used in various environments and requires low power consumption.

FIG. 12A shows a mobile phone, which has a main body 12
A display unit 1202 is provided on the upper front portion of 01. Mobile phones are used in all environments, indoors and outdoors.
It is often used in cars, but it is very dark at night. Therefore, a display device used in a mobile phone is preferably a semi-transmissive reflective liquid crystal device capable of mainly performing a reflective display with low power consumption and a transmissive display using auxiliary light as needed. The liquid crystal device of the present invention is brighter and brighter than the conventional liquid crystal device in both reflective display and transmissive display.

FIG. 12B shows a watch, which is a main body 12
A display unit 1204 is provided at the center of 03. In a watch application, the positional relationship between the liquid crystal device and the observer is almost fixed. However, the light source varies depending on the place of use. Even in such a case, the liquid crystal device of the invention can obtain a brighter display than the conventional one, and
It is also possible to get rid of the cheap feeling peculiar to a watch.

FIG. 12C shows a portable information device, which has a display unit 1206 above the main body 1205 and an input unit 120 below.
7 is provided. In addition, a touch key is often provided on the front surface of the display unit. Normal touch keys have a lot of surface reflections, so the display is difficult to see. However, the reflector of the present invention is
Since light is reflected more in the direction different from specular reflection, particularly in the direction normal to the surface of the liquid crystal device, there is an advantage that the visibility of the display is not impaired.

In all of these electronic devices, a transparent protective plate is often provided on the front surface of the liquid crystal device. FIG. 13 shows a sectional view of an electronic device provided with a transparent protective plate. In FIG. 13, 1301 is a liquid crystal device, 1302 is a transparent protective plate, 13
Reference numeral 03 is a housing. The liquid crystal device 1301 is the same as that described in the seventh embodiment. The transparent protective plate 1302 is made of transparent plastic, and the housing 1303 is made of opaque plastic. The surface of the transparent protective plate does not necessarily have to be flat, but it is arranged so as to be substantially parallel to the surface of the liquid crystal device.

With this structure, the light 1311 emitted from the light source 1304 in the oblique direction is reflected by the liquid crystal device of the present invention substantially in the normal direction 1312 and reaches the observer 1305. The light 1313 reflected by the surface of the transparent protective plate travels in the regular reflection direction and therefore does not reach the observer. Therefore, the provision of the transparent protection plate does not impair the contrast.

[0087]

As described above, according to the present invention, it is possible to provide a reflector that reflects a large amount of external light in a direction different from specular reflection. Further, the present invention can provide a liquid crystal device which is bright and has high contrast and less reflection of external light, particularly a reflective or semi-transmissive reflective monochrome or color liquid crystal device. Further, the present invention can provide an electronic device with low power consumption.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a structure of a reflector according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a main part of a structure of a light control plate used in a reflector in Examples 1 to 6 of the present invention.
(A) sectional drawing, (b) plan view.

FIG. 3 is a diagram showing the angle dependence of reflected light intensity of the reflector in Example 1 of the present invention.

FIG. 4 is a diagram showing a main part of a structure of a reflector according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a main part of a structure of a reflector in Example 3 of the present invention.

FIG. 6 is a diagram showing a main part of the structure of a reflective polarizing plate used in the reflectors of Examples 3, 4 and 6 of the present invention.

FIG. 7 is a diagram showing a main part of a structure of a reflector in a fourth embodiment of the present invention.

FIG. 8 is a diagram showing the angle dependence of the intensity of reflected light of a reflector in Example 4 of the present invention.

FIG. 9 is a diagram showing a main part of the structure of a reflector in Example 5 of the present invention.

FIG. 10 is a diagram showing a main part of a structure of a reflector in Example 6 of the present invention. (A) sectional drawing, (b) plan view.

FIG. 11 is a diagram showing a main part of a structure of a liquid crystal device according to a seventh embodiment of the present invention. (A) sectional drawing, (b) plan view.

FIG. 12 is a diagram showing an outer appearance of an electronic device according to a ninth embodiment of the present invention. (A) mobile phone, (b) watch,
(C) Portable information device.

FIG. 13 is a diagram showing a cross section of an electronic device according to a ninth embodiment of the present invention.

FIG. 14 is a diagram showing a main part of a structure of a conventional reflective liquid crystal device.

[Explanation of symbols]

101 light control plate 102 light reflection plate 103 light source 104 observer 111 incident light 112 reflected light in the normal direction 113 specular reflection light 201 light control plate 202 transparent layer 203 having a high refractive index 203 transparent layer 204 having a low refractive index On the other hand, light incident at a relatively high angle (transmitted through the light control plate) 205 Light incident at a relatively low angle on the layer interface (scattered by the light control plate) 206 Tilt angle of the layer structure 207 Scattering axis direction 501 light Control plate 502 Reflective polarizing plate 503 Light absorbing plate 504 Light source 505 Observer 511 Incident light 512 Reflected light in the normal direction 513 Specular reflected light 601 Layer 602 of material with high photoelasticity 603 Layer of material with low photoelasticity 603 Cartesian coordinate system, x-axis direction is stretching direction 701 Light control plate 702 Light scattering plate 703 Reflective polarizing plate 704 Light absorbing plate 801 Angle dependence of reflected light intensity in the reflector of FIG. Angular dependence of reflected light intensity at the reflector components except the light control plate 701 from the structure of sex 802 7

Continuation of the front page (56) Reference JP-A-9-166780 (JP, A) JP-A-9-127331 (JP, A) JP-A-1-147405 (JP, A) JP-A-8-221197 (JP , A) JP 10-186360 (JP, A) JP 9-15590 (JP, A) JP 7-36031 (JP, A) JP 8-179125 (JP, A) JP 3-107901 (JP, A) JP-A-7-64069 (JP, A) JP-A-8-271837 (JP, A) JP-A-57-197588 (JP, A) JP-A-49-130757 (JP, A) A) JP 52-68399 (JP, A) JP 52-83098 (JP, A) JP 61-270731 (JP, A) JP 63-309902 (JP, A) JP 64 -77001 (JP, A) Special Table 10-508152 (JP, A) Special Table 9-506985 (JP, A) International Publication 97/008583 (WO, A1) International Publication 97/001788 (WO, A1) ( 58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 5/02 G02B 5/08 G02F 1/1335

Claims (9)

(57) [Claims] 1. A liquid crystal cell in which a liquid crystal layer is sandwiched between an upper substrate and a lower substrate, and a light reflection plate provided on the lower substrate side.
In a liquid crystal device having a light control plate provided between the liquid crystal layer and the light reflection plate, the light control plate selectively scatters light incident at a predetermined angle and causes light other than the predetermined angle. The light control plate is made to transmit light incident at an angle, and the light control plate has a scattering axis direction in which the direction of selectively scattering the light incident at the predetermined angle is projected on the surface of the light control plate is in the liquid crystal cell plane. The liquid crystal device is arranged in the liquid crystal cell so as to be oriented in the direction of about 6 o'clock. 2. A liquid crystal cell in which a liquid crystal layer is sandwiched between an upper substrate and a lower substrate, and a light reflecting plate provided on the lower substrate side.
In a liquid crystal device having at least two light control plates provided between the liquid crystal layer and the light reflection plate, each of the light control plates selectively scatters light incident at a predetermined angle, A liquid crystal device, which transmits light incident at an angle other than the predetermined angle. 3. The at least two light control plates each have a scattering axis direction in which a direction that selectively scatters the light incident at the predetermined angle is projected on the surface of the light control plate, and each scattering axis. 3. The liquid crystal device according to claim 2, wherein the directions are different from each other. 4. The light control plate has a scattering axis direction in which a direction that selectively scatters incident light is projected on the surface of the light control plate, and the predetermined angle is at least a normal direction of the light control plate. 3. The liquid crystal device according to claim 1, wherein the liquid crystal device has an angle inclined by 10 to 20 degrees in the direction of the scattering axis. 5. The light control plate is formed by laminating a plurality of layers having different refractive indexes in a direction inclined with respect to the surface of the light control plate, and the layer of the light control plate is the light control plate. The liquid crystal device according to claim 1 or 2, wherein the liquid crystal device is inclined at an angle of 5 degrees or more and 20 degrees or less on average from the normal direction of the surface. 6. The light reflection plate is a reflection type polarizing plate having a transmission axis for transmitting or reflecting incident light and a reflection axis, and a light absorbing plate or a semi-light absorbing plate is provided on the back surface of the reflection type polarizing plate. The liquid crystal device according to claim 1, wherein the liquid crystal device is arranged. 7. The liquid crystal device according to claim 1, further comprising a light scattering plate on the surface of the light control plate. 8. The liquid crystal device according to claim 6, further comprising a backlight behind the light reflection plate. 9. An electronic apparatus comprising the liquid crystal device according to claim 1 as a display section.