JPH11160533A - Reflection polarizer, liquid crystal device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the reflection polarizer of a low polarization degree to light made incident from an oblique direction by alternately laminating many first layers provided with refractive index anisotropy within a plane and second layers not provided with the refractive index anisotropy within the plane and making the first layers be optically biaxial. SOLUTION: For this reflection polarizer, the two kinds of high polymer layers 101 and 102 are alternately laminated. Relating to the two kinds of high polymers, one is selected from the materials of a large photoelastic modulus and the other one is selected from the materials of a small photoelastic modulus and the refractive indexes of the ordinary rays of both are almost equal. The first layer 101 is provided with the refractive index anisotropy within the plane and the second layer 102 is hardly provided with the refractive index anisotropy within the plane. Also, the first layer 101 is optically biaxial. Among the light made incident obliquely within a y-z plane, the refractive index to the light vibrated within the y-z plane is different between the first layer 101 and the second layer 102. That is, as an incident angle becomes large, the ratio of reflected light increases and the polarization degree is degraded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective polarizer and a liquid crystal device, and more particularly, to an electronic apparatus equipped with the liquid crystal device.

[0002]

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

[0003] As one means for solving such a problem,
A method using a reflective polarizer using a birefringent dielectric multilayer film is disclosed in Japanese Patent Application Laid-Open No. 9-506985 or an internationally published international application (international application number: WO97 / 0178).
8), Conference Record of the 1997 International D
It is disclosed in isplay Research Conference, M-98, 1997 and the like.

The birefringent dielectric multilayer film has a function of reflecting a predetermined linearly polarized light component and transmitting other polarized light components. When such a reflective polarizer is used in a reflective liquid crystal device or a semi-transmissive reflective liquid crystal device, unlike a conventionally used metal reflector, it totally reflects light of a predetermined polarization component and also has an absorption polarizer. Because it does not absorb light like
It has the feature that a very bright display can be obtained.

[0005]

However, even when such a conventional reflective polarizer using a birefringent dielectric multilayer film is used, the reflective liquid crystal device still has a problem that the display is dark. The reflective liquid crystal device has another problem that a double image is generated due to parallax.

Accordingly, an object of the present invention is to provide a reflective polarizer having a low degree of polarization for light incident obliquely. Another object of the present invention is to provide a reflective or transflective liquid crystal device which is bright and makes it difficult to see a double image.

[0007]

According to a first aspect of the present invention, there is provided a reflective polarizer comprising a first layer having in-plane refractive index anisotropy and a second layer having no in-plane refractive index anisotropy. A reflective polarizer comprising a plurality of layers alternately stacked, wherein the first layer is optically biaxial. That a medium is optically biaxial means that there are two optical axes. The optical axis indicates an axial direction that does not exhibit birefringence.
Assuming that the three main refractive indices of the first layer are nx, ny, and nz, the fact that the first layer is optically biaxial means that nx
, Ny and nz are equivalent to taking different values. With this configuration, the reflection polarizer according to claim 1 has a low degree of polarization with respect to light incident from an oblique direction.

According to a second aspect of the present invention, there is provided the reflective polarizer according to the first aspect, wherein the three main refractive indices nx, ny, and nz of the first layer and the second layer are in the thickness direction. Refractive index n
The ratio of z and the refractive index ny in the direction perpendicular to the stretching direction in the plane is:
The two layers are different from each other. Although nx and ny exist in the in-plane principal refractive index, since this reflective polarizer is produced by stretching, the refractive index in the direction parallel to the principal stretching direction is nx, and the refractive index in the direction perpendicular to We will distinguish the rate from ny. Many substances are optically positive and therefore nx> ny, but optically negative substances such as polystyrene have nx <ny. Claim 2 indicates that nz / ny of the first layer is different from nz / ny of the second layer. With such a configuration, the reflective polarizer according to the second aspect has a low degree of polarization with respect to light incident from an oblique direction, and particularly reflects much of the light incident from the yz plane.

According to a third aspect of the present invention, there is provided the reflective polarizer of the first aspect, wherein the first layer has three main refractive indices n.
Among x, ny, and nz, the refractive index nz in the film thickness direction is smaller than the refractive index ny in the direction perpendicular to the stretching direction in the plane. With such a configuration, the reflective polarizer according to the third aspect has a low degree of polarization with respect to light incident from an oblique direction, and particularly transmits a large amount of light incident from the xz plane.

According to a fourth aspect of the present invention, there is provided a liquid crystal device comprising:
A polarizing plate that absorbs a predetermined linearly polarized light component and transmits the remaining polarized light component, a liquid crystal cell in which a liquid crystal composition is sandwiched between a pair of substrates provided with transparent electrodes, and has an in-plane refractive index anisotropy. A reflective polarizer, comprising a first layer and a second layer having no in-plane refractive index anisotropy alternately stacked, and a light absorbing plate, and these Wherein the reflection axis of the reflective polarizer is arranged substantially parallel to the left and right directions of the liquid crystal cell. The left-right direction of the liquid crystal cell is the horizontal direction. The term “substantially parallel” means that the horizontal direction is approximately ± 3
It refers to a range of 0 degrees, but more preferably refers to a range of ± 15 degrees. Outside of this range, the effects of the present invention can be obtained only in a special environment such as an oblique light source.
As the light absorbing plate, a plate having a high absorbance is used in a reflective liquid crystal device, and a plate having a low absorbance is used in a transflective liquid crystal device. The reflective polarizer has a poor degree of polarization in the direction of the transmission axis (axial direction orthogonal to the reflection axis) even if the constitutions of claims 1 to 3 are not taken. With such a configuration, the liquid crystal device according to claim 4 can provide a reflective or transflective display that is bright and hard to see a double image.

A liquid crystal device according to a fifth aspect of the present invention comprises at least
3. A reflection plate according to claim 1, wherein a polarizing plate absorbs a predetermined linearly polarized light component and transmits the remaining polarized light component, a liquid crystal cell having a liquid crystal composition sandwiched between a pair of substrates having a transparent electrode, and the reflection according to claim 1 or 2. A liquid crystal device comprising a polarizer and a light absorbing plate, which are arranged in the order described above, wherein the reflection axis of the reflective polarizer is substantially parallel to the left and right directions of the liquid crystal cell. And The term “substantially parallel” generally indicates a range of ± 30 degrees in the left-right direction, and more preferably a range of ± 15 degrees. Outside of this range, the effects of the present invention can be obtained only in a special environment such as an oblique light source. In this way, by combining the reflective polarizer of claim 1 or claim 2 with the liquid crystal device of claim 4, the liquid crystal device of claim 5 is brighter and of a reflective type or semi-transmissive reflective type in which a double image is hardly seen. Can be provided.

According to a sixth aspect of the present invention, there is provided a liquid crystal device comprising the reflective polarizer according to the first or third aspect and a liquid crystal composition sandwiched between a pair of substrates having a transparent electrode. Wherein the reflection axis of the reflective polarizer is substantially parallel to the vertical direction of the liquid crystal cell. The term “substantially parallel” generally indicates a range of ± 30 degrees in the left-right direction, and more preferably a range of ± 15 degrees. Outside of this range, the effects of the present invention can be obtained only in a special environment such as an oblique light source. With this configuration, even when the reflective polarizer is disposed on the upper side, the glaring luster peculiar to the reflective polarizer is suppressed, and a clear display can be achieved. Light incident from the 12:00 direction does not form an image and can be used for display as it is. Therefore, it is possible to provide a reflective or transflective display that is bright and hard to see a double image. If the lower polarizing plate of the liquid crystal device according to the sixth aspect is constituted by a reflective polarizer as described in the fourth and fifth aspects, an even brighter display is possible.

According to a seventh aspect of the invention, an electronic apparatus includes the liquid crystal device according to the fourth to sixth aspects as a display unit. With this configuration, the electronic device according to the seventh aspect consumes less power and can provide high-quality display.

[0014]

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

(Embodiment 1) FIG. 1 is a view showing a main part of the structure of a reflective polarizer according to the first to third aspects of the present invention. The reflective polarizer is basically a birefringent dielectric multilayer film, and is formed by alternately stacking two types of polymer layers 101 and 102. The two types of polymers are selected from a material with a high photoelastic modulus and a material with a low photoelastic modulus, while taking care that the refractive indices of the ordinary rays of both are approximately equal. . For example, PEN (2,6-polyethylene naphthalate) is selected as a material having a large photoelastic modulus, and coPEN (70-naphthalate / 30-terephthalate copolyester) is selected as a material having a small photoelastic modulus. Both films are alternately laminated, and the rectangular coordinate system 10 of FIG.
When the film was stretched about 5 times in the x-axis direction of No. 3, the refractive index in the x-axis direction was about 1.88 in the PEN layer and about 1.64 in the coPEN layer. The refractive index in the y-axis direction is PEN
Both the layer and the coPEN layer were about 1.64. When light is incident on the laminated film from the normal direction, the light component vibrating in the y-axis direction passes through the film as it is. This is the transmission axis. On the other hand, the light component oscillating in the x-axis direction is P
Reflection occurs only when the EN layer and the coPEN layer satisfy certain conditions. This is the reflection axis. The conditions are the optical path length (product of refractive index and film thickness) of the PEN layer, and co
The sum of the optical path length (the product of the refractive index and the film thickness) of the PEN layer is equal to half the wavelength of light. If such PEN layers and coPEN layers are laminated in several tens or more layers, preferably in more than one hundred layers, and in a thickness of about 30 μm, almost all of the components of light vibrating in the x-axis direction can be reflected.

An ideal reflective polarizer produced in this way produces a polarization capability only with a single designed wavelength of light. Of course, in practice, the thicknesses of the PEN layer and the coPEN layer vary, so that the polarization ability is generated with a certain wavelength width, but the width is still several tens of nm. Therefore, in order to provide a polarizing capability over a wide wavelength range of visible light, a plurality of reflective polarizers having different polarization reflection wavelength ranges are stacked with their axes aligned. The reflective polarizer thus configured is
It exhibited a high degree of polarization of 90% or more over almost the entire visible light range.

The above is a description of the behavior of light incident on the reflective polarizer from the normal direction. The main feature of the present invention lies in the behavior of light entering obliquely. FIG. 2 is a diagram showing the refractive index characteristics of two types of layers 101 and 102 constituting the reflective polarizer of the present invention. Reference numeral 201 denotes a refractive index ellipsoid of the first layer 101 formed by stretching a material having a large photoelastic coefficient, and reference numeral 202 denotes a refractive index ellipsoid of the second layer 102 formed by stretching a material having a small photoelastic coefficient. Let the three principal indices of each ellipsoid be nx, n
y and nz. However, the refractive indices 211 and 221 in a direction parallel to the main stretching direction in the plane of the layer (xy plane 231).
Is nx, the refractive indices 212 and 222 in the direction perpendicular to the main stretching direction in the plane of the layer are ny, and the refractive indices 213 and 2 in the film thickness direction are
23 is nz. However, the main stretching direction corresponds to the x-axis direction in FIG. 1 in the above description, and indicates a direction in which the stretching ratio is larger when biaxial stretching is performed.

The results of precisely measuring the refractive index of each layer of the reflective polarizers A and B of Example 1 and the reflective polarizer C for comparison are shown in Table 1. However, this measurement was performed using a film which was prepared separately from the first layer and the second layer and stretched in the same manner.

[0019]

[Table 1]

In any of the reflective polarizers, the first layer has in-plane refractive index anisotropy (nx-ny), and the second layer has almost no in-plane refractive index anisotropy. . Further, the first layers of the reflective polarizers A and B all have greatly different values of nx, ny, and nz. In particular, the reflective polarizer A has nz <ny, but the first layer of the reflective polarizer C has ny. And nz are almost equal. That is, the first layers of the reflective polarizers A and B are optically biaxial, while the first layer of the reflective polarizer C is optically uniaxial. Further, the ratio nz / n of nz and ny in the first layer
y and the ratio nz / ny of nz and ny in the second layer are:
Although the reflection polarizers A and B are significantly different, the reflection polarizer C is almost equal. Summarizing the above, the reflective polarizer A is the reflective polarizer according to the first to third aspects of the present invention, and the reflective polarizer B is the one according to the first or second aspect of the present invention. It is such a reflective polarizer.

When the nz / ny in the first layer and the nz / ny in the second layer are greatly different from each other as in the case of the reflective polarizers A and B, the light is incident obliquely in the yz plane. Of the light 242, the refractive index for light vibrating in the yz plane is different between the first layer and the second layer. That is, as the incident angle increases, the proportion of reflected light increases, and the degree of polarization deteriorates.

Also, as in the reflective polarizer A, n of the first layer
By configuring so that z is smaller than ny, of the light 241 obliquely incident on the xz plane, x
The refractive index for light oscillating in the −z plane decreases,
Birefringence disappears in the direction coinciding with the optical axis. That is, as the incident angle increases, the ratio of transmitted light increases, and the degree of polarization deteriorates.

FIG. 3 is a diagram showing the dependence of the degree of polarization on the angle of incident light. (A) is the incident light angle dependence in the xz plane, and (b) is the incident light angle dependence in the yz plane. 302 and 312 are characteristics of the reflective polarizer A, 303
And 313 are the characteristics of the reflective polarizer B, and 301 and 311 are the characteristics of the reflective polarizer C.

Both the reflective polarizers A and B have poor degrees of polarization with respect to light obliquely incident in the yz plane. This is because the polarized light that should be transmitted is reflected. Further, the reflection polarizer A also has a poor degree of polarization with respect to light obliquely incident on the xz plane. This is because polarized light that should be reflected is transmitted.

(Embodiment 2) FIG. 4 is a view showing a main part of the structure of a liquid crystal device according to the fourth or fifth aspect of the present invention. First, the configuration will be described. In FIG.
1 is a polarizing plate, 402 is a retardation film, 403 is an upper glass substrate, 404 is a liquid crystal layer, 405 is a lower glass substrate,
406 is a light scatterer, 407 is a reflective polarizer, 408 is a light absorber, 409 is a scanning electrode made of ITO, and 410 is an IT
O is a signal electrode. 401 and 402, 402 and 403, 405 and 406, 406 and 407, 407 and 4
08 are adhered to each other with glue. Although the upper and lower substrates are drawn widely apart, this is for the sake of clarity of the drawing, and they are actually opposed to each other with a narrow gap of several μm to tens of μm. In addition to the components shown in the figure, elements such as a liquid crystal alignment film, an insulating film, a spacer ball, a driver IC, and a drive circuit are also indispensable. Is omitted because it may be complicated and difficult to understand.

Next, each component will be described in order. The polarizing plate 401 has a function of absorbing a predetermined linearly polarized light component and transmitting other polarized light components. This is the most commonly used type of polarizing plate at present, and is produced by adsorbing a halogen substance such as iodine or a dichroic dye onto a polymer film such as polyvinyl butyral.

The retardation film 402 is, for example, a uniaxially stretched film of a polycarbonate resin, and is used for compensating the coloring of the display of the STN type liquid crystal device. T
In the case of an N-type liquid crystal device, it is often omitted.

The liquid crystal layer 404 is composed of a STN nematic liquid crystal composition twisted from 180 degrees to 270 degrees. When the display capacity is small, a TN liquid crystal composition twisted by 90 ° may be used. The twist angle is determined by the direction of the alignment treatment on the upper and lower glass substrates and the amount of the chiral agent added to the liquid crystal.

As the light scatterer 406, a plastic film in which transparent beads are dispersed can be used. Beads may be mixed in the adhesive and directly adhered to a liquid crystal device or the like. Alternatively, a light control plate that scatters only light incident from a specific angle may be used. Such a light control plate is sold by Sumitomo Chemical Co., Ltd. as Lumisty (trade name).
Note that the light scattering here refers to weak scattering that does not disturb the polarization. The light scattering plate is arranged for appropriately diffusing the reflected light of the reflective polarizer close to the mirror surface.

As the reflective polarizer 407, the reflective polarizer described in the first embodiment was used.

The light absorbing plate 408 is used by adhering a black vinyl sheet or black paper or by directly applying a black paint. In addition, if it is a relatively dark color other than black, it can be used depending on preference, such as blue, brown, and gray. This light absorbing plate is arranged for the purpose of absorbing unnecessary polarized light, but when this polarized light is used in a transflective liquid crystal device or the like,
What is necessary is just to use a translucent light absorption plate.

Next, specific conditions of the liquid crystal cell will be introduced.
First, the retardation (the product of the birefringence and the layer thickness) of the liquid crystal layer 404 in FIG.
02 was set to 0.65 μm. FIG. 5 is a diagram showing the relationship between the respective axes.
, 502 is the slow axis (stretching axis) of the retardation film, 503 is the rubbing axis of the upper glass substrate, 5
04 is the rubbing axis of the lower glass substrate, and 505 is the reflection axis of the reflective polarizer. Reference numeral 510 indicates the left-right direction (horizontal direction) of the liquid crystal cell. Here, the angle 511 between 501 and 502 is set to 58 degrees to the left, and the angle 51 between 502 and 503 is set to 51 degrees.
2 was set to 77 degrees to the left and 504 to 503, ie, the twist angle 513 of the liquid crystal was set to 240 degrees to the left, and the angle 514 to 505 was set to 504 was set to 44 degrees to the right. Since the two rubbing axes 503 and 504 are symmetric, the angle 515 between the polarization axis 505 of the reflective polarizer and the left-right direction 510 of the liquid crystal cell is formed.
Is 14 degrees to the right and can be said to be substantially parallel to the left and right directions.

The liquid crystal device thus manufactured has a feature that it is 30% or more brighter than a liquid crystal device using a normal polarizing plate. There are two reasons. One is that the reflectance of metallic aluminum is only slightly less than 90%, whereas the reflective polarizer of the present invention has almost one of the light parallel to the reflection axis.
This is because 00% is reflected. Another reason is that ordinary absorption-type polarizers use dichroic substances such as halogen substances such as iodine and dyes, and the dichroic ratio is not necessarily high, so that about 20% of light is wasted. That is what we do.

Further, this liquid crystal device is characterized in that a double image is unlikely to be generated and the brightness is high, especially when light is incident from above (12 o'clock direction). This is because when light is incident from above, the degree of polarization of the reflective polarizer 407 is low and the reflectance is high. This effect is due to the reflection polarizer C of the first embodiment.
Was higher when using the reflective polarizer A or B than when using.

The fact that the direction of the reflection axis of the reflective polarizer is substantially parallel to the left-right direction of the liquid crystal cell means that an expensive reflective polarizer having a complicated structure can be efficiently obtained from the raw material. It is advantageous.

(Embodiment 3) FIG. 6 is a view showing a main part of the structure of a liquid crystal device according to a sixth aspect of the present invention. First, the configuration will be described. 6, 601 is a reflective polarizer, 602 is a counter substrate, 603 is a liquid crystal composition, 604 is an element substrate, 605 is a light scattering plate, 606 is a reflective polarizer, and 6
07 is a light absorbing plate, 608 is a light guide plate of a backlight,
Reference numeral 9 denotes a light reflecting plate, 610 denotes a light source of a backlight, and a color filter 611 and a counter electrode (scanning line) 612 are provided on the counter substrate 602, and a signal line 613, a pixel electrode 614, and the like are provided on the element substrate 604. An MIM element 615 was provided.
Here, 601 and 602, 604 and 605, 605 and 60
6, 606 and 607 are drawn apart from each other for the sake of clarity of the figure, and are actually glued together. Further, the space between the opposing substrate 602 and the element substrate 604 is drawn widely apart, but for the same reason, there is actually only a gap of about several μm to about several tens μm.
FIG. 6 shows a part of the liquid crystal device. Therefore, three scanning lines 612 and three signal lines 616 cross each other.
Although only a × 3 matrix, that is, 9 dots, is shown, it actually has more dots.

The counter electrode 612 and the pixel electrode 614 were formed of transparent ITO. The signal line 613 was formed of metal Ta. In the MIM element, the insulating film Ta2O5 is made of metal Ta and metal C.
r. The liquid crystal composition 603 is a nematic liquid crystal twisted by 90 degrees. Reference numeral 611 denotes red (indicated by "R" in the figure) and green ("G" in the figure) which are three primary colors of additive color mixture.
) And blue (indicated by “B” in the figure) and arranged in a mosaic pattern.

Although the MIM active matrix type liquid crystal device has been described as an example here, the effect of the present invention is not changed even if a simple matrix type liquid crystal device is adopted. In such a case, connect the signal line to a rectangular IT
O is formed, and the MIM element and the pixel electrode are not provided. Also, instead of the TN mode, an STN mode similar to that of the second embodiment is employed.

The reflective polarizer A of Example 1 was used as the upper reflective polarizer 601. The lower reflective polarizer 606 is
The reflective polarizers A, B, and C of the first embodiment may be used,
An ordinary transflector with a polarizing plate may be used. In the latter case, 605 and 607 are unnecessary.

As the semi-light absorbing plate 607, a gray translucent film can be used. As a gray translucent film, 10% or more and 80% with respect to light in the entire wavelength range of visible light
A scattering film having a transmittance of 50% or more and 70% or less is suitable. Such a film is marketed, for example, by Tsujimoto Electric Manufacturing Co., Ltd. under the name of light diffusion film D202 (trade name). Further, a partially transparent light absorbing film, that is, a black film having a large number of fine holes having a diameter of several μm, which cannot be observed with the naked eye, can also be used. Further, the absorption type polarizing plate is changed to a reflection polarizer 60.
6 may be arranged off-axis.

As the light guide 608 of the backlight, a flat plate of acrylic resin having good transparency was used, and a white paint was printed on the surface thereof. A white light reflecting plate 609 is disposed on the back of the light guide to return light leaking backward to the front.

Next, specific conditions of the liquid crystal cell will be introduced.
First, the retardation (the product of the birefringence and the layer thickness) of the liquid crystal layer 603 in FIG. 6 was set to 0.42 μm. FIG. 7 is a diagram showing the relationship between each axis, and 701 is a reflective polarizer 601.
702, the rubbing axis of the upper glass substrate,
Reference numeral 3 denotes a rubbing axis of the lower glass substrate, and reference numeral 704 denotes a reflection axis of the reflective polarizer 606. Reference numeral 710 denotes the left-right direction (horizontal direction) of the liquid crystal cell. Here, 701, 702, 70
4 are parallel, and the angle 711 formed between them and 703 is set to 90 degrees. At this time, the upper reflective polarizer 601
The angle formed by the polarization axis 701 with the left-right direction 710 of the liquid crystal cell is 0 degree.

The liquid crystal device manufactured in this way is characterized in that a double image is hardly generated when the light is incident from the upper direction (12 o'clock direction), and the device is bright. This is because when light is incident from above, the degree of polarization of the reflective polarizer 601 is low and the transmittance is high. When a normal reflective polarizer is arranged on the viewer side of the liquid crystal cell, the specular reflection of the reflective polarizer impairs the display. However, the use of the reflective polarizer of the present invention can suppress such reflection.

The fact that the direction of the reflective axis of the reflective polarizer is substantially parallel to the vertical direction of the liquid crystal cell means that an expensive reflective polarizer having a complicated structure can be efficiently obtained from the raw material, and the cost is also low. It is advantageous.

(Embodiment 4) Three examples of the electronic device according to the seventh aspect of the present invention will be described.

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

FIG. 8A shows a mobile phone, and a main body 801.
The display unit 802 is provided in an upper part of the front surface of the. Mobile phones are used in all environments, both indoors and outdoors. Especially, it is often used in cars, but the inside of cars at night is very dark. Therefore, it is desirable that the display device used in the mobile phone is a transflective liquid crystal device capable of performing transmissive display using auxiliary light as needed, mainly reflective display with low power consumption. The liquid crystal device of the present invention is brighter than the conventional liquid crystal device in both the reflective display and the transmissive display, and it is difficult to see a double image peculiar to the reflective display.

FIG. 8B shows a watch, which is a main body 803.
The display unit 804 is provided at the center of the display. An important aspect in watch applications is luxury. The liquid crystal device of the present invention is not only bright, but also has little coloring due to a small characteristic change due to the wavelength of light. Also, double images are difficult to see. Therefore, a very high-quality display can be obtained as compared with the conventional liquid crystal device.

FIG. 8C shows a portable information device.
A display unit 806 is provided on the upper side of the display unit 05, and an input unit 807 is provided on the lower side. In addition, touch keys are often provided on the front of the display unit. Normal touch keys have many surface reflections,
The display is hard to see. Therefore, conventionally, a transmissive liquid crystal device has often been used even though it is portable. However, the transmissive liquid crystal device has a large power consumption that always uses a light source, and has a short battery life. Even in such a case, the liquid crystal device of the present invention can be used for a portable information device because the display is bright and vivid even in a reflective type or a transflective type.

[0050]

As described above, according to the present invention, it is possible to provide a reflective polarizer having a low degree of polarization with respect to light incident obliquely. Further, the present invention is a reflective or transflective liquid crystal device that is bright and hard to see a double image,
An electronic device with low power consumption can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a main part of a structure of a reflective polarizer according to a first embodiment of the present invention.

FIG. 2 is a diagram showing refractive index characteristics of two types of layers constituting a reflective polarizer in Example 1 of the present invention.

FIG. 3 is a diagram showing the incident angle dependence of the degree of polarization of the reflective polarizer in Example 1 of the present invention.

FIG. 4 is a diagram illustrating a main part of a structure of a liquid crystal device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between axes of a liquid crystal device according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a main part of a structure of a liquid crystal device according to a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a relationship between axes of a liquid crystal device according to a third embodiment of the present invention.

FIG. 8 is a diagram illustrating an appearance of an electronic device according to a fourth embodiment of the present invention. (A) mobile phone, (b) watch,
(C) portable information devices.

[Explanation of symbols]

Reference Signs List 101 Layer stretched with material having high photoelastic modulus 102 Layer stretched with material having low photoelasticity 103 Orthogonal coordinate system, x-axis direction is stretch direction, reflection axis 201 Index ellipsoid of layer 101 202 Refraction of layer 102 Index ellipsoid 211 Refractive index nx in a direction parallel to the main stretching direction in the plane of layer 101 nx 212 Refractive index ny 213 in a direction perpendicular to the main stretching direction in the plane of layer 101 Refractive index nz in the thickness direction of layer 101 221 Refractive index nx in the direction parallel to the main stretching direction in the plane of the layer 102 222 Refractive index ny 223 in the direction perpendicular to the main stretching direction in the plane of the layer 102 Refractive index nz 231 x− in the film thickness direction of the layer 102 y plane (plane parallel to the reflective polarizer surface) 232 xz plane (plane including both the extending direction and the thickness direction of the reflective polarizer) 233 yz plane (direction perpendicular to the extending direction of the reflective polarizer) Light incident from obliquely in the optical 242 y-z plane obliquely incident film thickness direction in both comprise plane) in 241 x-z plane

Claims (7)

[Claims] The present invention is characterized in that a plurality of first layers having in-plane refractive index anisotropy and a plurality of second layers having no in-plane refractive index anisotropy are alternately laminated. A reflective polarizer,
A reflective polarizer, wherein the first layer is optically biaxial. 2. The reflective polarizer according to claim 1, wherein the film extends in the plane with the refractive index nz in the film thickness direction among the three main refractive indices nx, ny and nz of the first layer and the second layer. A reflective polarizer, wherein the ratio of the refractive index ny in a direction perpendicular to the direction is different between the two layers. 3. The reflective polarizer according to claim 1, wherein, among the three main refractive indices nx, ny, and nz of the first layer, the refractive index nz in the film thickness direction is a direction perpendicular to the stretching direction in the plane. Refractive index n
A reflective polarizer characterized by being smaller than y. 4. A polarizing plate that absorbs at least a predetermined linearly polarized light component and transmits the remaining polarized light component, a liquid crystal cell having a liquid crystal composition sandwiched between a pair of substrates provided with transparent electrodes, A reflective polarizer comprising a first layer having refractive index anisotropy and a second layer having no in-plane refractive index anisotropy alternately stacked, and a light absorbing plate; And a liquid crystal device in which these are arranged in the above order, wherein the reflection axis of the reflective polarizer is arranged substantially parallel to the left and right direction of the liquid crystal cell. 5. A liquid crystal cell comprising a polarizing plate that absorbs at least a predetermined linearly polarized light component and transmits the remaining polarized light component, and a liquid crystal composition sandwiched between a pair of substrates provided with a transparent electrode. Or a liquid crystal device comprising the reflective polarizer according to claim 2 and a light absorbing plate, and these are arranged in the above order, wherein the reflection axis of the reflective polarizer is in the left-right direction of the liquid crystal cell. A liquid crystal device characterized by being substantially parallel. 6. A reflective polarizer according to claim 1 or 3, wherein the reflective polarizer is disposed on a viewer side of a liquid crystal cell having a liquid crystal composition sandwiched between a pair of substrates provided with a transparent electrode. A reflective axis of the reflective polarizer is substantially parallel to a vertical direction of a liquid crystal cell. 7. The liquid crystal device according to claim 4, wherein
An electronic device provided as a display unit.