WO2016084665A1

WO2016084665A1 - Optical modulation device, method for manufacturing optical modulation device, and display device

Info

Publication number: WO2016084665A1
Application number: PCT/JP2015/082338
Authority: WO
Inventors: 弘幸森脇; 忠大竹; 知子寺西; 佐藤　英次
Original assignee: シャープ株式会社
Priority date: 2014-11-25
Filing date: 2015-11-18
Publication date: 2016-06-02

Abstract

The present invention provides an optical modulation device having improved dispersion of shape-anisotropic members. This optical modulation device is provided, in order from the back surface side to the viewing surface side, with a first substrate, an optical modulation layer, and a second substrate, the optical modulation layer including shape-anisotropic members dispersed within liquid crystals. A first polarization plate is attached to the back surface side of the optical modulation device, and a second polarization plate is attached to the viewing surface side of the optical modulation device. When the transmission axis of the second polarization plate is rotated with respect to the transmission axis of the first polarization plate, the optical transmittance near the surfaces of the shape-anisotropic members changes, and the optical transmittance near the surfaces differs from the optical transmittance in areas other than those near the surfaces.

Description

LIGHT MODULATION DEVICE, LIGHT MODULATION DEVICE MANUFACTURING METHOD, AND DISPLAY DEVICE

The present invention relates to a light modulation device, a method for manufacturing the light modulation device, and a display device. More particularly, the present invention relates to a light modulation device that performs light modulation by controlling the orientation of a shape anisotropic member dispersed in liquid crystal, a method for manufacturing the light modulation device, and a display device including the light modulation device. It is.

As a light modulator, a liquid crystal panel using a pair of polarizing plates is well known. In this method, incident light to the liquid crystal panel is converted into polarized light by one polarizing plate, and polarized light that has passed through the liquid crystal layer is incident on the other polarizing plate, thereby controlling the transmittance of incident light to the liquid crystal panel. be able to. The liquid crystal layer can be used for controlling the polarization state because the orientation of the liquid crystal molecules in the liquid crystal layer changes according to the magnitude of the applied voltage. In this type of liquid crystal panel, more than half of the incident light is absorbed by the polarizing plate before the incident light passes through the liquid crystal panel, so there is a limit in improving the light utilization efficiency.

Therefore, an optical modulation device that does not require a polarizing plate has been proposed (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses an optical device that includes an electro-optically sensitive flake system suspended in a liquid host, and selectively changes its optical characteristics by changing the applied voltage. Patent Document 2 discloses a light modulation panel or display panel including a light modulation layer including a shape anisotropic member. Thus, a configuration has been proposed in which the shape anisotropic member in the light modulation layer is rotated according to the electric field to selectively change the optical characteristics of the light modulation layer.

On the other hand, plastic spacers are generally used to control the thickness of the liquid crystal layer of the liquid crystal panel. However, in such a configuration, liquid crystal molecules are abnormally aligned in the vicinity of the plastic spacer, thereby causing light leakage and reducing the contrast of the liquid crystal panel. Moreover, the plastic spacers sometimes aggregated. For this reason, a method of controlling the alignment state of the liquid crystal molecules in the vicinity of the plastic spacer by modifying the surface of the plastic spacer has been proposed (see, for example, Patent Documents 3 to 5).

Special table 2003-533736 gazette International Publication No. 2013/141051 JP-A-6-11719 Japanese Patent Laid-Open No. 9-244034 JP-A-8-262453

However, when a light modulation layer in which a shape anisotropy member is dispersed in liquid crystal is used, the dispersibility of the shape anisotropy member in the liquid crystal may be poor and may aggregate. For this reason, when a shape anisotropic member aggregates notably, even if a voltage is applied, a shape anisotropic member does not perform a desired operation | movement, The operation performance may fall. When the light modulation device is applied to a display device, the aggregation of the shape anisotropic member is caused by light transmittance (in the case of a display device in transmission display mode), light reflectance (in the case of a display device in reflection display mode), and contrast. The display performance such as the response speed is lowered. No means for solving such a problem has been found.

The present invention has been made in view of the above situation, and provides a light modulation device with improved dispersibility of a shape anisotropic member, a method for manufacturing the light modulation device, and a display device including the light modulation device. It is intended to do.

The inventors of the present invention have made various studies on improving the dispersibility of the shape anisotropic member in the light modulation device. As a result, the light modulation device controls the orientation of the shape anisotropic member by utilizing the change in the alignment state of the liquid crystal molecules. Then, it was noted that it is important to control the alignment state of the liquid crystal molecules in the vicinity of the surface of the shape anisotropic member. Therefore, the present inventors further examined that, as a combination of a liquid crystal and a shape anisotropic member, a polarizing plate was attached to the back side and the observation surface side of the light modulation device, and the transmission axis of the polarizing plate on the observation surface side was Is rotated with respect to the transmission axis of the polarizing plate on the back side, the light transmittance near the surface of the shape anisotropic member changes, and the light transmittance near the surface and the light in the region other than near the surface It has been found that a combination of materials having different transmittances is used. With such a configuration, the liquid crystal molecules are ordered with respect to the vicinity of the surface of the shape anisotropic member, and the alignment state of the liquid crystal molecules with respect to the vicinity of the surface of the shape anisotropic member Since the alignment state of the liquid crystal molecules in the region other than the vicinity of the surface of the conductive member is different, the shape anisotropic member is kept at an appropriate distance, and the light modulation device with improved dispersibility of the shape anisotropic member is realized. I found that I can do it. Thus, the inventors have conceived that the above problems can be solved brilliantly and have reached the present invention.

That is, one embodiment of the present invention is a light modulation device including a first substrate, a light modulation layer, and a second substrate in order from the back side to the observation surface side, and the light modulation layer includes: The shape anisotropic member is dispersed in the liquid crystal, the first polarizing plate is attached to the back side of the light modulation device, the second polarizing plate is attached to the observation surface side of the light modulation device, and When the transmission axis of the second polarizing plate is rotated with respect to the transmission axis of the first polarizing plate, the light transmittance in the vicinity of the surface of the shape anisotropic member changes, and the light in the vicinity of the surface The light modulation device may have different transmittance and light transmittance in a region other than the vicinity of the surface.

Another aspect of the present invention is a method of manufacturing the light modulation device, the step (1) of producing a mixture in which the shape anisotropic member is dispersed in the liquid crystal, and the first substrate. A method of manufacturing a light modulation device including the step (2) of forming the light modulation layer by disposing the mixture between the first substrate and the second substrate.

Still another embodiment of the present invention may be a display device including the light modulation device.

ADVANTAGE OF THE INVENTION According to this invention, the light modulation apparatus with which the dispersibility of the shape anisotropic member improved, the manufacturing method of the said light modulation apparatus, and a display apparatus provided with the said light modulation apparatus can be provided. In addition, since the display device of the present invention includes the light modulation device, the light transmittance (in the case of a display device in a transmissive display mode) and the light reflectance (in the reflective display mode) caused by aggregation of the shape anisotropic members. In the case of a display device), it is possible to prevent a decrease in display performance such as contrast and response speed.

FIG. 2 is a schematic cross-sectional view showing the light modulation device of Embodiment 1, wherein (a) shows a state when no voltage is applied, (b) shows a state when a voltage is applied (longitudinal electric field on), and (c) shows a voltage. The state at the time of application (lateral electric field ON) is shown. 3 is a schematic plan view illustrating an electrode structure disposed in the light modulation device of Embodiment 1. FIG. It is a cross-sectional schematic diagram which shows the suitable structure of a shape anisotropic member. FIG. 3 is a schematic cross-sectional view illustrating a state where light transmittance is observed with respect to the light modulation device according to the first embodiment. 3 is a schematic diagram illustrating an example of an alignment state of liquid crystal molecules and a shape anisotropic member in the light modulation device of Embodiment 1. FIG. FIG. 5 is a schematic cross-sectional view showing the light modulation device of Embodiment 2, wherein (a) shows a state when no voltage is applied, (b) shows a state when a voltage is applied (longitudinal electric field on), and (c) shows a voltage. The state at the time of application (lateral electric field ON) is shown. 6 is a schematic diagram illustrating an example of alignment states of liquid crystal molecules and shape anisotropic members in the light modulation device of Embodiment 2. FIG. It is a cross-sectional schematic diagram which shows the optical modulation apparatus of the comparative form 1, (a) shows the state at the time of no voltage application, (b) shows the state at the time of voltage application (longitudinal electric field ON), (c) is voltage The state at the time of application (lateral electric field ON) is shown. It is a plane schematic diagram which shows the electrode structure arrange | positioned at the light modulation apparatus of the comparative form 1. It is a cross-sectional schematic diagram which shows the state which observes the light transmittance with respect to the light modulation apparatus of the comparative form 1. FIG. It is a schematic diagram explaining the orientation state of a liquid crystal molecule and a shape anisotropic member in the light modulation device of comparative form 1. It is a photograph which shows the observation result of the light transmission state of the light modulation apparatus of Examples 1, 2, and 9. 6 is a photograph showing an observation result of a light transmission state of the light modulation device of Comparative Example 1; It is a photograph which shows the switching operation | movement evaluation result with respect to the light modulation apparatus of Example 1, 2, 9. 6 is a photograph showing a switching operation evaluation result for the light modulation device of Comparative Example 1;

Embodiments (Examples) are listed below, and the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited only to these embodiments (Examples). The configurations of the respective embodiments (each example) may be appropriately combined or changed within a range not departing from the gist of the present invention.

[Embodiment 1]
Embodiment 1 is a case where the liquid crystal molecules in the light modulation layer are aligned perpendicular to the vicinity of the surface of the shape anisotropic member.

(1) Structure of Light Modulation Device The structure of the light modulation device of Embodiment 1 will be described below. 1A and 1B are schematic cross-sectional views illustrating the light modulation device of the first embodiment, where FIG. 1A illustrates a state when no voltage is applied, FIG. 1B illustrates a state when a voltage is applied (longitudinal electric field ON), c) shows a state when a voltage is applied (lateral electric field is on). FIG. 2 is a schematic plan view illustrating an electrode structure disposed in the light modulation device according to the first embodiment. As shown in FIG. 1, the light modulation device 1a includes a first substrate 2a, a light modulation layer 3, and a second substrate 2b in order from the back side to the observation surface side. The 1st board | substrate 2a and the 2nd board | substrate 2b are bonded together through the sealing material (not shown) arrange | positioned so that a display area may be enclosed. In this specification, “observation surface side” indicates the upper side of the light modulation device 1a in FIG. “Back side” in FIG. 1 indicates the lower side of the light modulation device 1a. The same applies to other sectional views.

The first substrate 2a includes a support substrate 4a, a pair of

electrodes

5a and 5b, and a vertical alignment film 7a in order from the back surface side to the observation surface side.

As the support substrate 4a, for example, a transparent substrate such as a glass substrate or a plastic substrate can be used. When a foldable plastic substrate is used as the transparent substrate, a flexible light modulation device can be realized.

The pair of

electrodes

5a and 5b has an in-plane switching (IPS) type electrode structure. Specifically, the pair of

electrodes

5a and 5b are a pair of comb-teeth electrodes in which mutual comb teeth are fitted. As shown in FIG. 2, the

electrodes

5a and 5b have a trunk portion and a plurality of parallel branch portions (comb teeth) extending from the trunk portion. ) Are alternately arranged. As shown in FIG. 1C, by applying a voltage between the electrode 5a and the electrode 5b with an AC power supply (AC), a lateral electric field (with respect to the first substrate 2a) is applied to the light modulation layer 3. Parallel electric fields). The

electrodes

5a and 5b are made of a conductive material, and can be made of a metal material such as indium tin oxide (ITO) or aluminum. When the light modulation device of Embodiment 1 is applied to a display device in a transmissive display mode, the

electrodes

5a and 5b are preferably formed of a transparent conductive material such as ITO. On the other hand, when the light modulation device of Embodiment 1 is applied to a display device in the reflective display mode, the

electrodes

5a and 5b may not be formed of a transparent conductive material.

The vertical alignment film 7a is disposed so as to cover at least the entire display region. That is, the initial alignment of the liquid crystal molecules 9 in the light modulation layer 3 is set in a direction perpendicular to the first substrate 2a. The vertical alignment film 7a is not particularly limited as long as the liquid crystal molecules 9 are aligned substantially vertically with respect to the surface thereof. For example, a film made of polyimide or polyamic acid showing a known vertical alignment property is used. Can be used. The vertical alignment film 7a may be subjected to a rubbing process, and may be subjected to a photo-alignment process for irradiating polarized light (for example, polarized ultraviolet rays) as long as it is a photo-alignable vertical alignment film.

The second substrate 2b includes a support substrate 4b, a counter electrode 6, an insulating film 8, and a vertical alignment film 7b in order from the observation surface side to the back surface side.

As the support substrate 4b, the same substrate as the support substrate 4a of the first substrate 2a can be used.

The counter electrode 6 is disposed in a plane so as to face the pair of

electrodes

5a and 5b and cover the entire display area. As shown in FIG. 1B, a vertical electric field (first substrate) is applied to the light modulation layer 3 by applying a voltage between the

electrodes

5a, 5b and the counter electrode 6 with an alternating current power supply (AC). 2a and the electric field perpendicular to the second substrate 2b). The counter electrode 6 is made of a conductive material, and can be made of a metal material such as ITO or aluminum. When the light modulation device of Embodiment 1 is applied to a display device in a transmissive display mode, the counter electrode 6 is preferably formed of a transparent conductive material such as ITO. Similarly, when the light modulation device of Embodiment 1 is applied to a display device in the reflective display mode, the counter electrode 6 is preferably formed of a transparent conductive material such as ITO.

By disposing the insulating film 8 together with the counter electrode 6, a lateral electric field can be effectively formed in the light modulation layer 3.

The vertical alignment film 7b is disposed in the same manner as the vertical alignment film 7a of the first substrate 2a.

At least one of the first substrate 2a and the second substrate 2b may be an active matrix substrate. The active matrix substrate has switching elements arranged in a plurality of pixels arranged in a matrix and various wirings. As the switching element, for example, a thin film transistor (TFT) element is used. Examples of the various wirings include a gate bus line that supplies a scanning signal to the TFT, a source bus line that supplies a display signal to the TFT, and a common wiring. When the first substrate 2a is an active matrix substrate, the pair of

electrodes

5a and 5b are arranged for each pixel, one of which is electrically connected to the source bus line via the switching element, and the other is a common wiring. Is electrically connected. When one of the first substrate 2a and the second substrate 2b is an active matrix substrate, the other substrate may be a color filter substrate. Thereby, color display can be performed.

The light modulation layer 3 is obtained by dispersing the shape anisotropic member 10 in liquid crystal. By using liquid crystal as the dispersion medium of the shape anisotropic member 10, the orientation of the shape anisotropic member 10 can be controlled by utilizing the change in the alignment state of the liquid crystal molecules 9. The liquid crystal molecules 9 and the shape anisotropic member 10 change directions in the light modulation layer 3 in accordance with the vertical electric field and the horizontal electric field as described above. For this reason, the light modulation layer 3 can control the transmittance of incident light.

The liquid crystal molecule 9 may be a positive type (p type) having a positive dielectric anisotropy (Δε> 0), but a negative type (n type) having a negative dielectric anisotropy (Δε <0). ). From the viewpoint of improving the operation performance of the shape anisotropic member 10 with respect to the electric field strength, the liquid crystal molecules 9 are preferably p-type. In this case, the dielectric anisotropy of the liquid crystal molecules 9 is preferably Δε> 10, and more preferably Δε> 20.

The shape anisotropic member 10 only needs to have anisotropy in its shape, and when viewed from the normal direction of the surface of the first substrate 2a (second substrate 2b), the first substrate 2a (second The projected area on the substrate 2b) may be any shape that continuously changes in response to voltage application. Further, the projected area when the major axis of the shape anisotropic member 10 is oriented parallel to the first substrate 2a (second substrate 2b) is more than twice the projected area when oriented vertically. Preferably there is. As such a shape, for example, a flake shape (flakes) is preferable, and a disk shape is particularly preferable. Other examples include a cylindrical shape and an elliptical sphere. The thickness of the shape anisotropic member 10 is not particularly limited. For example, in the case of a flake shape, the thickness is preferably 1 μm or less, and more preferably 0.1 μm or less. The smaller the thickness of the shape anisotropic member 10, the smaller the projected area onto the first substrate 2a (second substrate 2b) when oriented vertically, so that a black display with high transmittance and less scattering is obtained. be able to. Furthermore, the shape anisotropic member 10 preferably has a light reflective surface.

In the light modulation device according to the first embodiment, the shape anisotropic member 10 has the liquid crystal molecules 9 aligned perpendicular to the vicinity of the surface thereof. The shape anisotropic member 10 is oriented perpendicular to the main surfaces of the first substrate 2a and the second substrate 2b when no voltage is applied. That is, when no voltage is applied, the alignment direction of the liquid crystal molecules 9 with respect to the vicinity of the surface of the shape anisotropic member 10 is orthogonal to the alignment direction of the liquid crystal molecules 9 in a region other than the vicinity of the surface of the shape anisotropic member 10. ing. Thereby, the dispersibility of the shape anisotropic member 10 can further be improved. The vicinity of the surface of the shape anisotropic member 10 indicates a range within 1 μm from the surface of the shape anisotropic member 10. The main surfaces of the first substrate 2a and the second substrate 2b indicate surfaces on the opposite sides.

As the shape anisotropic member 10 in which the liquid crystal molecules 9 are aligned perpendicularly to the vicinity of the surface, for example, a member having a polymer layer on the outer surface as shown in FIG. 3 is preferable. FIG. 3 is a schematic cross-sectional view showing a preferred configuration of the shape anisotropic member. As shown in FIG. 3, it is preferable that the shape anisotropic member 10 has a polymer layer 12 on the outer surface, that is, a configuration in which the polymer layer 12 is disposed outside the core portion 11. As a method for forming such a polymer layer 12, for example, a technique for surface modification of a plastic spacer disclosed in Patent Documents 3 to 5 can be used. As a material of the core part 11 of the shape anisotropic member 10, for example, a metal, a semiconductor, a dielectric, and a composite material thereof can be used.

When a metal is used as the material of the core part 11, aluminum flakes are suitable. The core portion 11 may be formed of a dielectric multilayer film or cholesteric resin, or may be colored. The core part 11 may be in a state where the material (for example, aluminum) is exposed or covered with an insulating film such as an acrylic resin.

As shown in FIG. 3A, the polymer layer 12 may be composed of a single layer of a coating layer 13 that covers the core portion 11, but is shown in FIG. 3B. As described above, a two-layer structure composed of a coating layer 13 (first polymer layer) covering the core portion 11 and a surface modification layer 14 (second polymer layer) modifying the surface of the coating layer 13 is formed. It is more preferable to have it. According to such a two-layer structure, the polymers forming the coating layer 13 are polymerized by surrounding the core portion 11, so that the coating layer 13 does not leave the core portion 11, and the surface modification layer 14 It is also possible to have a structure in which the polymer that forms the polymer is polymerized with the polymer that forms the coating layer 13, so that the surface modification layer 14 does not leave the coating layer 13. When the polymer layer 12 has such a two-layer structure, a polymer having a large amount of reactive groups that easily bind to the surface modification layer 14 on the surface, such as silanol groups, is selected as the coating layer 13 to modify the surface. As the layer 14, a polymer having silanol groups is selected, and these silanol groups are reacted with each other to form a covalent bond by condensation polymerization, so that the surface modification layer 14 does not leave the coating layer 13 and is anisotropic in shape. The dispersibility of the adhesive member 10 can be preferably improved. Moreover, when the material of the core part 11 is a metal (for example, aluminum), the coating layer 13 can be arrange | positioned in order to prevent the conduction | electrical_connection through the core part 11, or to control a dielectric constant. On the other hand, the surface modification layer 14 can be disposed for the purpose of improving the dispersibility of the shape anisotropic member 10. Therefore, as the material of the coating layer 13 and the surface modification layer 14, materials can be selected according to the purpose. However, when an alignment film (for example, a vertical alignment film) is used as the material of the polymer layer 12, it is not formed by a chemical bond, so that it is easily detached during a voltage application / non-application switching operation. Absent.

The specific gravity of the shape anisotropy member 10, it preferably at 11g / cm ³ or less, more preferably 3 g / cm ³ or less, which is equivalent to the liquid crystal specific gravity (e.g., 1 g / cm ³ or less) Is more preferable. When the specific gravity of the shape anisotropic member 10 is much larger than the specific gravity of the liquid crystal, there is a concern that the shape anisotropic member 10 will settle in the light modulation layer 3.

Next, a light transmission state and a light reflection state in the light modulation device of the first embodiment will be described.

FIG. 1A shows a state in which no voltage is applied to the

electrodes

5a and 5b and the counter electrode 6. FIG. FIG. 1A shows the case where p-type liquid crystal molecules 9 are used. As shown in FIG. 1A, the liquid crystal molecules 9 are aligned perpendicular to the vicinity of the surface of the shape anisotropic member 10, and the first liquid crystal molecules 9 are formed in regions other than the vicinity of the surface of the shape anisotropic member 10. The substrate 2a and the second substrate 2b are oriented perpendicular to the main surface. The liquid crystal molecules 9 are aligned perpendicularly to the main surfaces of the first substrate 2a and the second substrate 2b in a region other than the vicinity of the surface of the shape anisotropic member 10. The liquid crystal molecules 9 may be aligned substantially perpendicularly to the main surfaces of the first substrate 2a and the second substrate 2b in a region other than the vicinity. The first substrate 2a and the second substrate 2b It indicates that the tilt angle of the liquid crystal molecules 9 with respect to the main surface of the substrate 2b is not less than 75 ° and not more than 90 °. The shape anisotropic member 10 is oriented perpendicular to the main surfaces of the first substrate 2a and the second substrate 2b. For this reason, incident light passes through the light modulation layer 3 directly or after being reflected by the shape anisotropic member 10 and then transmitted to the side opposite to the incident side. For example, when light is incident from the first substrate 2a side, the light path is indicated by an arrow in FIG.

FIG. 1B shows a state in which a voltage is applied between the

electrodes

5a and 5b and the counter electrode 6 (longitudinal electric field on). FIG. 1B shows the case where p-type liquid crystal molecules 9 are used. As shown in FIG. 1B, the liquid crystal molecules 9 are aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, and the first liquid crystal molecules 9 are formed in regions other than the vicinity of the surface of the shape anisotropic member 10. The substrate 2a and the second substrate 2b are oriented perpendicular to the main surface. The shape anisotropy member 10 has its major axis changed to an electric force line by the dielectrophoretic force, the Coulomb force, the force explained from the viewpoint of electric energy, and the force that minimizes the interface energy with the liquid crystal. It rotates so that it becomes parallel to it. For example, if a material having visible light reflectivity such as a thin metal piece is used as the shape anisotropic member 10, the reflective surfaces of the shape anisotropic member 10 are the first substrate 2 a and the second substrate. Oriented perpendicular to the major surface of 2b. For this reason, incident light is transmitted directly to the light modulation layer 3 or reflected by the reflecting surface of the shape anisotropic member 10 and then transmitted to the side opposite to the incident side. For example, in the case where light is incident from the first substrate 2a side, the light path is indicated by an arrow in FIG.

As described above, a light transmission state can be realized. In such a light transmissive state, for example, if a light source such as a backlight is disposed on the back side of the light modulation device 1a, a display device in a transmissive display mode can be realized.

FIG. 1C shows a state in which a voltage is applied between the

electrodes

5a and 5b (lateral electric field on). FIG. 1C shows the case where p-type liquid crystal molecules 9 are used. As shown in FIG. 1C, the liquid crystal molecules 9 are aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10 and the first substrate in a region other than the vicinity of the surface of the shape anisotropic member 10. In the vicinity of 2a, it is oriented parallel to the main surface of the first substrate 2a. The liquid crystal molecules 9 are aligned in the vicinity of the first substrate 2a in the region other than the vicinity of the surface of the shape anisotropic member 10 in parallel with the main surface of the first substrate 2a. The liquid crystal molecules 9 may be aligned substantially parallel to the main surface of the first substrate 2a in the vicinity of the first substrate 2a in a region other than the region, and the liquid crystal molecules 9 of the first substrate 2a It indicates that the tilt angle is 0 ° or more and 25 ° or less. In this case, the liquid crystal molecules 9 move from the vicinity of the second substrate 2b toward the vicinity of the first substrate 2a where the lateral electric field strength is large, from the state perpendicular to the main surface of the first substrate 2a. It may fall down in a parallel state according to the size of the. The shape anisotropy member 10 has its major axis changed to an electric force line by the dielectrophoretic force, the Coulomb force, the force explained from the viewpoint of electric energy, and the force that minimizes the interface energy with the liquid crystal. It rotates so that it becomes parallel to it. For example, if a material having visible light reflectivity such as a thin metal piece is used as the shape anisotropic member 10, the reflective surfaces of the shape anisotropic member 10 are the first substrate 2 a and the second substrate. Oriented parallel to the main surface of 2b. For this reason, incident light is reflected to the incident side by the reflecting surface of the shape anisotropic member 10. For example, in the case where light is incident from the first substrate 2a side, the light path is indicated by an arrow in FIG. As described above, a light reflection state can be realized. Further, when the shape anisotropic member 10 is oriented on the same plane, the brightest (highest light utilization efficiency) light reflection state is obtained.

When the light modulation device of Embodiment 1 is applied to a display device, in such a light transmission state and light reflection state, for example, if a colored layer is disposed on the back side of the first substrate 2a, the shape is anisotropic. When the reflective surface of the conductive member 10 is oriented perpendicular to the main surfaces of the first substrate 2a and the second substrate 2b, the color of the colored layer is displayed. On the other hand, when the reflective surface of the shape anisotropic member 10 is oriented parallel to the main surfaces of the first substrate 2a and the second substrate 2b, the reflection by the shape anisotropic member 10 is performed. The color is displayed. For example, if the color of the colored layer is black and the shape anisotropic member 10 is a thin metal piece, the reflective surface of the shape anisotropic member 10 is the main surface of the first substrate 2a and the second substrate 2b. On the other hand, when it is oriented vertically, a black display is obtained. On the other hand, when the reflective surface of the shape anisotropic member 10 is oriented in parallel to the main surfaces of the first substrate 2a and the second substrate 2b, display by reflected light from a thin metal piece Is obtained. Furthermore, the average diameter of the metal flakes is, for example, 20 μm or less, the surface of the shape anisotropic member 10 is made light-scattering, or the contour of the shape anisotropic member 10 is formed into a shape with severe irregularities. The reflected light from the anisotropic member 10 is scattered, and white display can be obtained. In addition, when a reflective layer for specular reflection or scattering reflection is disposed on the back side of the first substrate 2a and the shape anisotropic member 10 is colored, the reflection surface of the shape anisotropic member 10 is the first. When oriented perpendicular to the main surfaces of the substrate 2a and the second substrate 2b, display of reflected light on the reflective layer is obtained. On the other hand, when the reflecting surface of the shape anisotropic member 10 is oriented parallel to the main surfaces of the first substrate 2a and the second substrate 2b, the colored shape anisotropic member 10 is colored. Is displayed. By disposing the light modulation device 1a on a non-display surface of a mobile phone or the like, the color of the body of the mobile phone and the color of the colored shape anisotropic member 10 can be switched and displayed. Further, halftone display can be performed using the inclination of the shape anisotropic member 10 in a state between the light transmission state and the light reflection state depending on the magnitude of the applied voltage.

In the light modulation device according to the first embodiment, the liquid crystal and the shape anisotropic member 10 included in the light modulation layer 3 are attached to the back side and the observation surface side of the light modulation device 1a. When the transmission axis of the second polarizing plate) is rotated with respect to the transmission axis of the back side polarizing plate (first polarizing plate), the light transmittance near the surface of the shape anisotropic member 10 changes, In addition, the light transmittance in the vicinity of the surface of the shape anisotropic member 10 and the light transmittance in a region other than the vicinity of the surface of the shape anisotropic member 10 are combinations of materials. Here, the observation of the light transmittance as described above is performed in a state as shown in FIG. FIG. 4 is a schematic cross-sectional view illustrating a state in which light transmittance is observed with respect to the light modulation device of the first embodiment. As shown in FIG. 4, the light transmittance is observed using a polarizing microscope, a first polarizing plate 15a is attached to the back side of the light modulation device 1a, and a second light is observed on the observation surface side of the light modulation device 1a. The polarizing plate 15b is attached, and the transmission axis of the second polarizing plate 15b is rotated with respect to the transmission axis of the first polarizing plate 15a. Specifically, the light modulation device 1a is placed on the stage of a polarizing microscope, the orientation of the transmission axis of the polarizer (corresponding to the first polarizing plate 15a), and the analyzer (on the second polarizing plate 15b). The transmission axis of the analyzer is set to have a predetermined relationship (for example, crossed Nicols (orthogonal state)), and the transmission axis of the analyzer is rotated with respect to the transmission axis of the polarizer in transmission observation. Thus, the method is performed by observing the vicinity of the surface of the shape anisotropic member 10 and the vicinity thereof. In this case, the direction of the shape anisotropic member 10 may be set to have a predetermined relationship with the direction of the transmission axis of the polarizer and the analyzer. A general instrument can be used as the polarizing microscope. As the polarizer and analyzer, for example, a linear polarizer can be used, and it is preferable to use a polarizer that exhibits an absorbance of 99% or more when placed in crossed Nicols. The light transmittance changes when the transmission axis of the second polarizing plate 15b is rotated by 15 ° with respect to the transmission axis of the first polarizing plate 15a. For example, the light transmittance changes by 20% or more. Realizing a light modulation device in which the dispersibility of the shape anisotropic member 10 is improved by using the light modulation layer 3 including the liquid crystal in which the light transmittance is in the above state and the shape anisotropic member 10. Can do. This effect is particularly remarkable when a flaky member is used as the shape anisotropic member 10.

In the light modulation device of the first embodiment, the liquid crystal molecules 9 are perpendicular to the main surfaces of the first substrate 2a and the second substrate 2b in a region other than the vicinity of the surface of the shape anisotropic member 10. The transmission axis of the first polarizing plate 15a and the transmission axis of the second polarizing plate 15b are attached to crossed Nicols, and the transmission axis of the second polarizing plate 15b is set to the transmission axis of the first polarizing plate 15a. When rotated counterclockwise, if the clockwise direction is positive and the counterclockwise direction is negative, the shape anisotropic member 10 increases the light transmittance near the surface with respect to the positive rotation direction, and in the negative rotation direction. On the other hand, the shape anisotropic member (first shape anisotropic member) in which the light transmittance near the surface decreases, and the light transmittance in the vicinity of the surface decreases with respect to the positive rotation direction, and in the negative rotation direction. On the other hand, there are few of the shape anisotropic members (second shape anisotropic members) whose light transmittance near the surface increases. And wherein one also for the positive and negative direction of rotation, it is preferable that the light transmittance of the region other than the vicinity of the surface of the shape anisotropy member 10 does not change. Here, it is sufficient that the above-described light transmittance state exists at least when the transmission axis of the second polarizing plate 15b is rotated. By using the light modulation layer 3 including the liquid crystal in which the light transmittance is in the above state and the shape anisotropic member 10, a light modulation device in which the dispersibility of the shape anisotropic member 10 is further improved is realized. be able to. This effect is particularly remarkable when a flaky member is used as the shape anisotropic member 10.

The state of light transmittance in the light modulation device of Embodiment 1 has been described above. An example of the alignment state of the liquid crystal molecules 9 and the shape anisotropic member 10 that realize such a state will be described below. FIG. 5 is a schematic diagram illustrating an example of alignment states of liquid crystal molecules and shape anisotropic members in the light modulation device of the first embodiment. FIG. 5 corresponds to a state (plan view) when the state shown in FIG. 4 is viewed from the observation surface side.

Consider a case where the transmission axis of the first polarizing plate 15a and the transmission axis of the second polarizing plate 15b are attached to crossed Nicols. In FIG. 5, the dotted double-pointed arrow indicates the direction of the transmission axis of the first polarizing plate 15a, the solid-line double-pointed arrow indicates the direction of the transmission axis of the second polarizing plate 15b, and the transmission axes are orthogonal to each other. Yes. In the following description, the clockwise direction is defined as positive (+) with reference to the azimuth (0 °) of the transmission axis of the second polarizing plate 15b, and the angle and the azimuth of the axis are described. Thus, from the state (crossed Nicol state) in which the transmission axis (azimuth: 90 °) of the first polarizing plate 15a and the transmission axis (azimuth: 0 °) of the second polarizing plate 15b are orthogonal to each other, FIG. When the transmission axis of the second polarizing plate 15b is rotated by −15 ° and + 15 ° with respect to the transmission axis of the first polarizing plate 15a as shown in (a) and (b) of FIG. The light transmittance near the surface of the conductive member 10 changes, and the light transmittance near the surface of the shape anisotropic member 10 is different from the light transmittance in other regions. Further, the shape anisotropic member 10 increases the light transmittance near the surface with respect to the positive rotation direction of the second polarizing plate 15b, and decreases the light transmittance near the surface with respect to the negative rotation direction. The light transmittance near the surface with respect to the positive rotation direction of the shape anisotropic member (FIG. 5B) and the second polarizing plate 15b decreases, and the light near the surface with respect to the negative rotation direction. Including a shape anisotropic member ((a) of FIG. 5) in which the transmittance increases, and in a region other than the vicinity of the surface of the shape anisotropic member 10 with respect to the positive and negative rotation directions of the second polarizing plate 15b. The light transmittance does not change. For this reason, the light transmitted through the liquid crystal molecules 9 oriented with respect to the vicinity of the surface of the shape anisotropic member 10 is considered to be elliptically polarized light as shown in FIGS.

First, the alignment state of the liquid crystal molecules 9 realizing the elliptical polarization state as shown in FIG. 5A will be described with reference to FIG. As shown in FIG. 5C, when the liquid crystal molecules 9 are aligned perpendicular to the vicinity of the surface of the shape anisotropic member 10, it can be seen by comparing FIGS. 5A and 5C. In addition, the direction of the refractive index no with respect to ordinary light of the liquid crystal molecules 9 is tilted by + 45 ° and the direction of the refractive index ne with respect to extraordinary light is tilted by −45 ° with respect to the transmission axis of the first polarizing plate 15a. As the optical phase difference axis, the no direction of the liquid crystal molecules 9 corresponds to the fast axis, and the ne direction of the liquid crystal molecules 9 corresponds to the slow axis. When the transmission axis of the first polarizing plate 15a and the alignment state of the liquid crystal molecules 9 are in the relationship as shown in FIGS. 5A and 5C, the linearly polarized light transmitted through the first polarizing plate 15a is shaped. When the liquid crystal molecules 9 that are aligned with respect to the vicinity of the surface of the anisotropic member 10 are transmitted, the light becomes counterclockwise elliptically polarized light as shown in FIG.

Next, the alignment state of the liquid crystal molecules 9 realizing the elliptical polarization state as shown in FIG. 5B will be described with reference to FIG. As shown in FIG. 5D, when the liquid crystal molecules 9 are aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, it can be seen by comparing FIGS. 5B and 5D. In addition, the direction of the refractive index no with respect to the ordinary light of the liquid crystal molecules 9 is inclined by −45 ° and the direction of the refractive index ne with respect to the extraordinary light is inclined by + 45 ° with respect to the transmission axis of the first polarizing plate 15a. When the transmission axis of the first polarizing plate 15a and the alignment state of the liquid crystal molecules 9 are as shown in FIGS. 5B and 5D, the linearly polarized light transmitted through the first polarizing plate 15a has a shape. When the liquid crystal molecules 9 oriented with respect to the vicinity of the surface of the anisotropic member 10 are transmitted, clockwise elliptical polarization as shown in FIG. 5B is obtained.

From the above, as an example of the orientation state of the shape anisotropic member 10 in the light modulation device of Embodiment 1, the shape anisotropic member 10 rotates clockwise with respect to the transmission axis of the first polarizing plate 15a when no voltage is applied. And a shape anisotropic member (FIG. 5B) oriented perpendicularly to the main surface of the first substrate 2a and the second substrate 2b, and the first polarized light A shape-anisotropic member that intersects the transmission axis of the plate 15a counterclockwise at 45 ° and is oriented perpendicularly to the principal surfaces of the first substrate 2a and the second substrate 2b (see FIG. d)).

According to the light modulation device of the first embodiment, the liquid crystal molecules 9 are ordered (perpendicularly) with respect to the vicinity of the surface of the shape anisotropic member 10 and the liquid crystal molecules with respect to the vicinity of the surface of the shape anisotropic member 10 are used. 9 is different from the alignment state of the liquid crystal molecules 9 in a region other than the vicinity of the surface of the shape anisotropic member 10, so that the dispersibility of the shape anisotropic member 10 can be improved. Moreover, the orientation of the shape anisotropic member 10 when no voltage is applied can be improved by improving the dispersibility of the shape anisotropic member 10. In the light modulation device of the first embodiment, the liquid crystal molecules 9 are aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10. The state only needs to be ordered, and in addition to the case where the state is vertical, the case where the state is parallel as described later is preferable. From the viewpoint of sufficiently improving the dispersibility of the shape anisotropic member 10, the liquid crystal molecules 9 are preferably aligned perpendicular to the vicinity of the surface of the shape anisotropic member 10. When the light modulation device according to the first embodiment is applied to a display device, the light transmittance (in the case of a display device in a transmissive display mode) and the light reflectance (reflection display) caused by aggregation of shape anisotropic members. In the case of a mode display device), it is possible to prevent a decrease in display performance such as contrast and response speed.

In addition, the light modulation device of Embodiment 1 controls the transmitted light amount or the reflected light amount by changing the direction of the shape anisotropic member 10 by an electrical action. Therefore, unlike a liquid crystal panel using a polarizing plate, it is not necessary to dispose polarizing plates on the back side of the first substrate 2a and the observation surface side of the second substrate 2b in actual use. For this reason, the light modulation device of the first embodiment is excellent in light utilization efficiency.

(2) Manufacturing Process of Light Modulation Device A manufacturing process of the light modulation device of Embodiment 1 will be described below.

(A) Preparation of mixture (step (1))
A mixture in which the shape anisotropic member 10 is dispersed in the liquid crystal is prepared. At this time, the shape anisotropic member 10 may be cleaned in advance. Examples of the cleaning method include a method of performing ultrasonic irradiation in a state where isopropyl alcohol (IPA), acetone or the like is added. Further, as described with reference to FIG. 3, the outer surface of the shape anisotropic member 10 may be covered with the polymer layer 12 in advance. As a method for forming such a polymer layer 12, for example, a technique for surface modification of a plastic spacer disclosed in Patent Documents 3 to 5 can be used.

(B) Formation of light modulation layer (step (2))
The light modulation layer 3 is formed by disposing the mixture in which the shape anisotropic member 10 is dispersed in the liquid crystal between the first substrate 2a and the second substrate 2b, thereby completing the light modulation device 1a. . As a method for forming the light modulation layer 3, a method of dropping the mixture onto at least one of the first substrate 2a and the second substrate 2b and then bonding the both substrates in a vacuum or in the atmosphere may be used. Then, after bonding the first substrate 2a and the second substrate 2b, a method of injecting the mixture between both the substrates in a vacuum or a method of injecting using the capillary phenomenon may be used.

Examples relating to the light modulation device according to the first embodiment will be described below. In each of the following examples, a flake-shaped member was used as the shape anisotropic member 10.

(Example 1)
Example 1 is a case where the shape anisotropic member 10 having a polymer layer 12 on the outer surface was used, and the polymer layer 12 was composed of a coating layer 13 and a surface modification layer 14. This is a case of having a two-layer structure. The manufacturing process of the light modulation device of Example 1 was as follows.

(A) Preparation of the mixture The shape anisotropic member 10, liquid crystal, and plastic beads for controlling the thickness of the light modulation layer 3 were mixed, and ultrasonic irradiation was performed for 60 minutes to prepare a mixture. As the shape anisotropic member 10, a material composed of aluminum flakes as the core portion 11, silica-based insulator A 1 as the coating layer 13, and a hydrophilic polymer B 1 as the surface modification layer 14 is used. The average particle size was 7 μm. The shape anisotropic member 10 used was washed in advance. As a cleaning method, first, the operation of performing centrifugation after repeating the ultrasonic irradiation with IPA added is repeated three times, and then performing the centrifugal separation after performing the ultrasonic irradiation with adding acetone. The operation was repeated three times, and finally the method of natural drying was used. The mixing amount of the shape anisotropic member 10 was 10 wt% with respect to the liquid crystal. As the liquid crystal, a fluorine-based liquid crystal (Δε = 20.4) manufactured by Merck & Co. was used. As the plastic beads, plastic beads (trade name: Micropearl) manufactured by Sekisui Chemical Co., Ltd. were used, and the average particle size was 10 μm. The mixing amount of the plastic beads was 0.2 wt% with respect to the liquid crystal.

(B) After the light modulation layer formation mixture was dropped onto the first substrate 2a, the light modulation layer 3 was formed by bonding the first substrate 2a and the second substrate 2b in the atmosphere. The thickness of the light modulation layer 3 was 10 μm. In the first substrate 2a, the material of the pair of

electrodes

5a and 5b is ITO, the electrode width is 10 μm, the electrode interval (space) is 10 μm, and the thickness is 100 nm. In the second substrate 2b, the material for the counter electrode 6 was ITO, and the thickness was 100 nm. The material for the insulating film 8 was an overcoat material (dielectric constant εr = 3.4) used for color filter applications manufactured by Toppan Printing Co., Ltd., and the thickness was 3 μm. As the

vertical alignment films

7a and 7b, an alignment film (trade name: SE-4811, surface free energy: 35.0) manufactured by Nissan Chemical Industries, Ltd. was used, and the thickness thereof was 100 nm. Thus, the light modulation device 1a is completed. With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

(Example 2)
The second embodiment is a case where the configuration of the shape anisotropic member 10 is changed with respect to the first embodiment. Except for this point, the optical modulation device of the second embodiment and its manufacturing process are the same as the optical modulation device of the first embodiment and its manufacturing process, and therefore, overlapping description is omitted.

The shape anisotropic member 10 is composed of aluminum flakes as the core 11, acrylic insulator A 2 as the coating layer 13, and a hydrophobically treated polymer B 2 having an alkyl group as the surface modification layer 14. The average particle size was 7 μm. With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

(Example 3)
The third embodiment is a case where the configuration of the shape anisotropic member 10 is changed with respect to the first embodiment. Except for this point, the optical modulation device of the third embodiment and its manufacturing process are the same as those of the optical modulation device of the first embodiment and its manufacturing process.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 0.1 g of sodium lauryl sulfate were added to 1000 ml of water, and in a state where they were stirred, 2.5 g of tetramethylol methane triacrylate, 4.5 g of divinylbenzene, and 0.8 g of benzoyl peroxide. Then, the polymerization reaction was carried out at 90 ° C. for 2 hours. The product after the polymerization reaction was filtered using a polyvinylidene fluoride (PVDF) filter (pore size: 1 μm) with water, methanol and acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugal separation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. A flake in which the coating layer 13 was coated on the part 11 (aluminum flake) was obtained. The coating layer 13 was a polymer of monomers (tetramethylolmethane triacrylate and divinylbenzene) having an ethylenically unsaturated group.

Next, 3 g of flakes coated with the coating layer 13 and 3 g of dodecyltriethoxysilane were added to 100 ml of hexane, and a polymerization reaction was performed in a 50 ° C. environment under a nitrogen stream for 1 hour. The polymerized reaction product was filtered using a PVDF filter (pore size: 1 μm) with hexane and acetone added. Subsequently, the flakes collected by filtration were collected with acetone, divided into small portions, subjected to centrifugation and decantation in this order, and then reacted by heating in an environment of 140 ° C. for 1 hour. The product after the heating reaction was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added is repeated twice, followed by drying under reduced pressure. The shape anisotropic member 10 in which the surface modification layer 14 for modifying the surface of the layer 13 was formed was obtained. The surface modification layer 14 was formed from an organosilane compound (dodecyltriethoxysilane). With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

Example 4
The fourth embodiment is a case where the configuration of the shape anisotropic member 10 is changed with respect to the first embodiment. The optical modulation device and the manufacturing process thereof according to the fourth embodiment are the same as those of the optical modulation device and the manufacturing process thereof according to the first embodiment except for this point.

As the shape anisotropic member 10, one formed by the following method was used. First, 12 g of aluminum flakes and 0.3 g of hydroxypropylcellulose were added to 300 ml of ethanol, and with stirring, 12 g of γ-methacryloxypropyltrimethoxysilane, 13.5 g of styrene, and 2,2′-azo After adding 0.2 g of bisisobutyronitrile, the polymerization reaction was carried out for 2 hours in a 70 ° C. environment under a nitrogen stream. The product after the polymerization reaction was filtered using a PVDF filter (pore size: 1 μm) with ethanol and acetone added. Subsequently, the collected flakes were collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added thereto was repeated three times to perform drying under reduced pressure. 10 g of flakes after drying under reduced pressure and 1.5 g of methacryloyl isocyanate were added to 100 ml of methyl ethyl ketone, and reacted for 20 minutes in an environment at room temperature (25 ° C.). The product after the reaction was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugal separation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. A flake in which the coating layer 13 was coated on the part 11 (aluminum flake) was obtained. The coating layer 13 was a polymer having a carboxyl group on the surface.

Next, 325 g of methyl alcohol, 9.4 g of ethylene glycol, 30 g of polyvinyl pyrrolidone, 4 g of cetanol, 5 g of isobornyl methacrylate, 7.5 g of glycidyl methacrylate, and 7.5 g of lauryl methacrylate were charged into the reactor. Polymer particles having an epoxy group and a long-chain alkyl group on the surface by adding 1.2 g of '-azobis (2-methylbutyronitrile) and performing precipitation polymerization in an environment of 60 ° C. in a nitrogen stream for 5 hours. Prepared separately. The polymer particles were crushed and dried after washing, and had a true spherical shape. The average particle size was 0.35 μm.

Next, 8 g of flakes coated with the coating layer 13 and 24 g of the polymer particles obtained above were treated for 3 minutes using an OM dizer of a hybridization system manufactured by Nara Machinery Co., Ltd. Formed. After that, the ordered anisotropy is subjected to film formation at a rotational speed of 15000 rpm for 5 minutes using a hybridizer of a hybridization system, so that the surface modification layer 14 for modifying the surface of the coating layer 13 is formed. Member 10 was obtained. The surface modification layer 14 is a polymer having a long-chain alkyl group, and forms a covalent bond with the coating layer 13. With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

(Example 5)
The fifth embodiment is a case where the configuration of the shape anisotropic member 10 is changed with respect to the first embodiment. The optical modulation device and its manufacturing process of the fifth embodiment are the same as those of the optical modulation device and its manufacturing process of the first embodiment except for this point.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 0.1 g of hydroxypropylcellulose were added to 300 ml of ethanol, and with stirring, 4 g of γ-methacryloxypropyltrimethoxysilane, 4.5 g of styrene, and 2,2′-azo After adding 0.1 g of bisisobutyronitrile, a polymerization reaction was performed for 2 hours in a 70 ° C. environment under a nitrogen stream. The product after the polymerization reaction was filtered using a PVDF filter (pore size: 1 μm) with ethanol and acetone added. Subsequently, the collected flakes were collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added thereto was repeated three times to perform drying under reduced pressure. The flakes after drying under reduced pressure had —SiOH groups on the surface. Subsequently, 3 g of flakes after drying under reduced pressure and 0.5 g of methacryloyl isocyanate were added to 100 ml of methyl ethyl ketone, and reacted for 20 minutes in an environment at room temperature (25 ° C.). The product after the reaction was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugal separation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. A flake in which the coating layer 13 was coated on the part 11 (aluminum flake) was obtained.

Next, 1 g of flakes coated with the coating layer 13, 0.01 g of benzoyl peroxide, 1 g of methacrylic acid, and 1 g of methyl methacrylate are added to 30 ml of methyl ethyl ketone, and a polymerization reaction is performed in an environment of 90 ° C. in a nitrogen stream for 1 hour. It was. The polymerized reaction product was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes were collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added thereto was repeated three times to perform drying under reduced pressure. Subsequently, 100 g of xylene, 3 g of octyl methacrylate and 2.5 g of lauryl polyoxyethylene methacrylate were charged all at once with respect to 2.5 g of the flakes after drying under reduced pressure, and the temperature was raised to the polymerization initiator cleavage temperature (25 ° C.). Thereafter, a graft polymerization reaction was performed in a nitrogen stream for 1 hour, thereby obtaining the shape anisotropic member 10 on which the surface modification layer 14 for modifying the surface of the coating layer 13 was formed. The surface modification layer 14 was graft polymerized with the coating layer 13 and had a graft polymer chain having a long-chain alkyl group.

(Example 6)
The sixth embodiment is a case where the configuration of the shape anisotropic member 10 is changed with respect to the first embodiment. Except for this point, the optical modulation device and the manufacturing process thereof according to the sixth embodiment are the same as the optical modulation device and the manufacturing process thereof according to the first embodiment.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 0.1 g of hydroxypropylcellulose were added to 300 ml of ethanol, and with stirring, 4 g of γ-methacryloxypropyltrimethoxysilane, 4.5 g of styrene, and 2,2′-azo After adding 0.1 g of bisisobutyronitrile, a polymerization reaction was performed for 2 hours in a 70 ° C. environment under a nitrogen stream. The product after the polymerization reaction was filtered using a PVDF filter (pore size: 1 μm) with ethanol and acetone added. Subsequently, the collected flakes were collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added thereto was repeated three times to perform drying under reduced pressure. The flakes after drying under reduced pressure had —SiOH groups on the surface. Subsequently, 3 g of flakes after drying under reduced pressure and 0.5 g of methacryloyl isocyanate were added to 100 ml of methyl ethyl ketone, and reacted for 20 minutes in an environment at room temperature (25 ° C.). The product after the reaction was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugal separation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. A flake in which the coating layer 13 was coated on the part 11 (aluminum flake) was obtained. The coating layer 13 was a polymer having a polymerizable vinyl group capable of radical chain transfer on the surface.

Next, 3 g of flakes coated with the coating layer 13, 3 g of toluene solution added with 70 wt% of t-butylperoxyallyl carbonate, 3 g of methyl methacrylate and 0.01 g of benzoyl peroxide were added to 300 ml of methyl ethyl ketone, The polymerization reaction was carried out in an environment of 90 ° C. for 1 hour. The polymerized reaction product was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes were collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added thereto was repeated three times to perform drying under reduced pressure. The flakes after drying under reduced pressure had graft polymer chains containing peroxide groups on the surface. Subsequently, 100 g of xylene, 3 g of octyl methacrylate and 2.5 g of lauryl polyoxyethylene methacrylate were charged all at once with respect to 2.5 g of the flakes after drying under reduced pressure, and the temperature was raised to the polymerization initiator cleavage temperature (25 ° C.). Thereafter, a graft polymerization reaction was performed in a nitrogen stream for 1 hour, thereby obtaining the shape anisotropic member 10 on which the surface modification layer 14 for modifying the surface of the coating layer 13 was formed. The surface modification layer 14 was graft polymerized with the coating layer 13 and had a graft polymer chain having a long-chain alkyl group. With such a configuration, since the coverage of the polymer layer 12 is increased, the liquid crystal molecules 9 can be aligned perpendicular to the vicinity of the surface of the shape anisotropic member 10, and the aggregation of the shape anisotropic member 10 can be performed. Can be prevented and its dispersibility can be improved.

(Example 7)
The seventh embodiment is a case where the configuration of the shape anisotropic member 10 is changed with respect to the first embodiment. Except for this point, the optical modulation device and the manufacturing process thereof according to the seventh embodiment are the same as the optical modulation device and the manufacturing process thereof according to the first embodiment.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 0.1 g of sodium lauryl sulfate were added to 1000 ml of water, and after stirring them, 4.5 g of divinylbenzene and 0.8 g of benzoyl peroxide were added. The polymerization reaction was allowed to proceed for 2 hours. The product after the polymerization reaction was filtered using a PVDF filter (pore diameter: 1 μm) with water, methanol and acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugal separation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. A flake in which the coating layer 13 was coated on the part 11 (aluminum flake) was obtained. The coating layer 13 was a polymer of a plastic material (divinylbenzene).

Next, 3 g of flakes coated with the coating layer 13 was added to a solution of 0.3 g of silicon tetrachloride dissolved in 30 ml of n-hexane and stirred for 15 minutes in an environment at room temperature (25 ° C.). The product after stirring was filtered using a glass filter and then air-dried. After air drying, 3 g of triisopropylaluminum alkoxide was added to 100 ml of toluene, and ultrasonic irradiation was performed for 5 minutes in an environment at room temperature (25 ° C.). The product after ultrasonic irradiation was added to a mixed solution of 50 ml of methanol and 50 ml of water for hydrolysis. The hydrolyzed product was filtered using a PVDF filter (pore size: 1 μm) with methanol and acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and centrifugation, decantation, and ultrasonic irradiation with acetone added are sequentially repeated three times, followed by drying under reduced pressure. The shape anisotropic member 10 in which the surface modification layer 14 for modifying the surface of the layer 13 was formed was obtained. The surface modification layer 14 was an aluminum alkoxide polycondensate having hydrophilicity. The surface modification layer 14 forms an aluminosilicate bond with the coating layer 13. With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can. Here, as the surface modification layer 14, an aluminum alkoxide polycondensate that forms an alumino titanate bond or an alumino zirconate bond instead of the aluminosilicate bond with the coating layer 13 may be used.

(Example 8)
Example 8 is a case where the configuration of the shape anisotropic member 10 is changed with respect to Example 1. The optical modulation device and the manufacturing process thereof according to the eighth embodiment are the same as those of the optical modulation device and the manufacturing process thereof according to the first embodiment except for this point.

As the shape anisotropic member 10, one formed by the following method was used. First, a flake in which the core 11 (aluminum flake) was coated with a coating layer 13 made of silica was prepared. Next, 3 g of flakes coated with the coating layer 13 and 3 g of octadecyltriethoxysilane were added to 100 ml of hexane, and a polymerization reaction was performed in a 50 ° C. environment in a nitrogen stream for 1 hour. The polymerized reaction product was filtered using a PVDF filter (pore size: 1 μm) with hexane and acetone added. Subsequently, the flakes collected by filtration were collected with acetone, divided into small portions, subjected to centrifugation and decantation in this order, and then reacted by heating in an environment of 140 ° C. for 1 hour. The product after the heating reaction was filtered using a PVDF filter (pore size: 1 μm) with acetone added. Subsequently, the collected flakes are collected with acetone, divided into small portions, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added is repeated twice, followed by drying under reduced pressure. The shape anisotropic member 10 in which the surface modification layer 14 for modifying the surface of the layer 13 was formed was obtained. The surface modification layer 14 was an alkyl silane coupling agent (formed from an organic silane compound). With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can. Thus, a polymer having a large amount of silanol groups (silica) is selected as the coating layer 13, and a polymer having a silanol group (alkyl silane coupling agent) is selected as the surface modification layer 14, and these silanol groups are selected. A strong covalent bond having a large amount of an alkyl chain can be formed by dehydrating and condensing each other through a hydrogen bond. As a result, the surface modification layer 14 does not leave the coating layer 13, and the dispersibility of the shape anisotropic member 10 can be preferably improved.

Example 9
Example 9 is a case where the shape anisotropic member 10 having the polymer layer 12 on the outer surface is used, and the polymer layer 12 is composed of a single layer of the coating layer 13. Since the optical modulation device and the manufacturing process thereof according to the ninth embodiment are the same as the optical modulation device and the manufacturing process thereof according to the first embodiment except for this point, the description of overlapping points is omitted.

As the shape anisotropic member 10, an aluminum flake as the core part 11 and an acrylic insulator A2 as the coating layer 13 were used, and the average particle diameter was 7 μm. With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

(Example 10)
Example 10 is a case where the configuration of the shape anisotropic member 10 is changed with respect to Example 9. The optical modulation device and the manufacturing process thereof according to the tenth embodiment are the same as the optical modulation device and the manufacturing process thereof according to the ninth embodiment except for this point.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 4 g of polyethylene glycol (weight average molecular weight: 1,000,000) were added to 500 ml of water, and in a state where they were stirred, 2.5 g of glycidyl methacrylate, 4.5 g of divinylbenzene, and benzoyl peroxide 0 were added. After adding 1 g, the polymerization reaction was carried out in an environment of 90 ° C. for 2 hours. The product after the polymerization reaction was filtered using a PVDF filter (pore diameter: 1 μm) with water, methanol and acetone added. Subsequently, the collected flakes are collected with acetone, subdivided, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. The shape anisotropic member 10 in which the coating layer 13 was coated on the part 11 (aluminum flakes) was obtained. The coating layer 13 was an ethylene glycol polymer (polyethylene glycol). With such a configuration, since the alignment regulating force on the liquid crystal molecules 9 is weakened, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, and aggregation of the shape anisotropic member 10 can be prevented. And the dispersibility can be improved.

(Example 11)
Example 11 is a case where the configuration of the shape anisotropic member 10 is changed with respect to Example 9. The optical modulation device and the manufacturing process thereof according to the eleventh embodiment are the same as the optical modulation device and the manufacturing process thereof according to the ninth embodiment except for this point.

As the shape anisotropic member 10, one formed by the following method was used. First, after adding 4 g of aluminum flakes and 0.1 g of sodium lauryl sulfate to 1000 ml of water and stirring them, 4 g of nonylphenol ethylene oxide, 4.5 g of divinylbenzene, and 0.8 g of benzoyl peroxide were added. The polymerization reaction was performed in an environment of 90 ° C. for 2 hours. The product after the polymerization reaction was filtered using a PVDF filter (pore diameter: 1 μm) with water, methanol and acetone added. Subsequently, the collected flakes are collected with acetone, subdivided, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. The shape anisotropic member 10 in which the coating layer 13 was coated on the part 11 (aluminum flakes) was obtained. The coating layer 13 contained nonylphenol ethylene oxide adduct. With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

Example 12
Example 12 is a case where the configuration of the shape anisotropic member 10 is changed with respect to Example 9. Except for this point, the optical modulation device of the twelfth embodiment and the manufacturing process thereof are the same as the optical modulation device of the ninth embodiment and the manufacturing process thereof.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 0.1 g of sodium lauryl sulfate were added to 1000 ml of water, and with stirring, 4.5 g of 2,2,2-trifluoroethyl methacrylate, 6 g of divinylbenzene, ethylene glycol dimethacrylate 2 .3 g and 0.8 g of benzoyl peroxide were added, and the polymerization reaction was carried out in an environment of 90 ° C. for 2 hours. The product after the polymerization reaction was filtered using a PVDF filter (pore diameter: 1 μm) with water, methanol and acetone added. Subsequently, the collected flakes are collected with acetone, subdivided, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. The shape anisotropic member 10 in which the coating layer 13 was coated on the part 11 (aluminum flakes) was obtained. The coating layer 13 is a single monomer having a crosslinkable monomer (divinylbenzene) having two or more ethylenically unsaturated groups, a fluorine monomer (2,2,2-trifluoroethyl methacrylate), and ethylene glycol. It was formed from a copolymer with a monomer (ethylene glycol dimethacrylate). With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can. Here, in the coating layer 13 as described above, a monomer having a glycidyl group may be used instead of the fluorine-based monomer, and both the fluorine-based monomer and the monomer having a glycidyl group are used. May be.

(Example 13)
Example 13 is a case where the configuration of the shape anisotropic member 10 is changed with respect to Example 9. Except for this point, the light modulation device of the thirteenth embodiment and the manufacturing process thereof are the same as those of the light modulation device of the ninth embodiment and the manufacturing process thereof.

As the shape anisotropic member 10, one formed by the following method was used. First, 4 g of aluminum flakes and 0.1 g of sodium lauryl sulfate were added to 1000 ml of water, and 4 g of glycidyl methacrylate, 6 g of divinylbenzene, and 0.8 g of benzoyl peroxide were added in a state where these were stirred. The polymerization reaction was carried out for 2 hours under the following conditions. The product after the polymerization reaction was filtered using a PVDF filter (pore diameter: 1 μm) with water, methanol and acetone added. Subsequently, the collected flakes are collected with acetone, subdivided, and the operation of sequentially performing centrifugation, decantation, and ultrasonic irradiation with acetone added is repeated three times, and dried under reduced pressure. The shape anisotropic member 10 in which the coating layer 13 was coated on the part 11 (aluminum flakes) was obtained. The coating layer 13 was a polymer of a monomer having a glycidyl group (glycidyl methacrylate). With this configuration, the liquid crystal molecules 9 can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member 10, preventing aggregation of the shape anisotropic member 10 and improving its dispersibility. it can.

[Embodiment 2]
Embodiment 2 is a case where the liquid crystal molecules in the light modulation layer are aligned parallel to the vicinity of the surface of the shape anisotropic member. Except for this point, the optical modulation device and the manufacturing process thereof according to the second embodiment are the same as the optical modulation device and the manufacturing process thereof according to the first embodiment.

(1) Structure of Light Modulation Device The structure of the light modulation device of Embodiment 2 will be described below. 6A and 6B are schematic cross-sectional views showing the light modulation device of the second embodiment, where FIG. 6A shows a state when no voltage is applied, FIG. 6B shows a state when a voltage is applied (longitudinal electric field ON), c) shows a state when a voltage is applied (lateral electric field is on). As shown in FIG. 6, the light modulation device 1b includes a first substrate 2a, a light modulation layer 3, and a second substrate 2b in order from the back surface side to the observation surface side.

In the light modulation device of the second embodiment, the shape anisotropic member 10 has the liquid crystal molecules 9 aligned in parallel to the vicinity of the surface, that is, in the plane perpendicular to the paper surface in FIG. It is preferable that they are oriented in the same direction within a plane perpendicular to the paper surface. As the shape anisotropic member 10 in which the liquid crystal molecules 9 are aligned in parallel to the vicinity of the surface, for example, a member having a polymer layer on the outer surface as shown in FIG.

Next, a light transmission state and a light reflection state in the light modulation device of the second embodiment will be described.

FIG. 6A shows a state in which no voltage is applied to the

electrodes

5a and 5b and the counter electrode 6. FIG. FIG. 6A shows the case where p-type liquid crystal molecules 9 are used. As shown in FIG. 6A, the liquid crystal molecules 9 are aligned in parallel to the vicinity of the surface of the shape anisotropic member 10, and in the region other than the vicinity of the surface of the shape anisotropic member 10, the first The substrate 2a and the second substrate 2b are oriented perpendicular to the main surface. The shape anisotropic member 10 is oriented perpendicular to the main surfaces of the first substrate 2a and the second substrate 2b. For this reason, incident light passes through the light modulation layer 3 directly or after being reflected by the shape anisotropic member 10 and then transmitted to the side opposite to the incident side. For example, in the case where light is incident from the first substrate 2a side, the light path is indicated by an arrow in FIG.

FIG. 6B shows a state in which a voltage is applied between the

electrodes

5a and 5b and the counter electrode 6 (longitudinal electric field on). FIG. 6B shows a case where p-type liquid crystal molecules 9 are used. As shown in FIG. 6B, the liquid crystal molecules 9 are aligned in parallel to the vicinity of the surface of the shape anisotropic member 10, and in the region other than the vicinity of the surface of the shape anisotropic member 10, the first The substrate 2a and the second substrate 2b are oriented perpendicular to the main surface. The shape anisotropy member 10 has its major axis changed to an electric force line by the dielectrophoretic force, the Coulomb force, the force explained from the viewpoint of electric energy, and the force that minimizes the interface energy with the liquid crystal. It rotates so that it becomes parallel to it. For example, if a material having visible light reflectivity such as a thin metal piece is used as the shape anisotropic member 10, the reflective surfaces of the shape anisotropic member 10 are the first substrate 2 a and the second substrate. Oriented perpendicular to the major surface of 2b. For this reason, incident light is transmitted directly to the light modulation layer 3 or reflected by the reflecting surface of the shape anisotropic member 10 and then transmitted to the side opposite to the incident side. For example, in the case where light is incident from the first substrate 2a side, the light path is indicated by an arrow in FIG.

As described above, a light transmission state can be realized. In such a light transmissive state, for example, if a light source such as a backlight is disposed on the back side of the light modulation device 1b, a display device in a transmissive display mode can be realized.

FIG. 6C shows a state in which a voltage is applied between the

electrodes

5a and 5b (lateral electric field on). FIG. 6C shows the case where p-type liquid crystal molecules 9 are used. As shown in FIG. 6C, the liquid crystal molecules 9 are aligned in parallel to the vicinity of the surface of the shape anisotropic member 10, and the first substrate in a region other than the vicinity of the surface of the shape anisotropic member 10. In the vicinity of 2a, it is oriented parallel to the main surface of the first substrate 2a. The shape anisotropy member 10 has its major axis changed to an electric force line by the dielectrophoretic force, the Coulomb force, the force explained from the viewpoint of electric energy, and the force that minimizes the interface energy with the liquid crystal. It rotates so that it becomes parallel to it. For example, if a material having visible light reflectivity such as a thin metal piece is used as the shape anisotropic member 10, the reflective surfaces of the shape anisotropic member 10 are the first substrate 2 a and the second substrate. Oriented parallel to the main surface of 2b. For this reason, incident light is reflected to the incident side by the reflecting surface of the shape anisotropic member 10. For example, in the case where light is incident from the first substrate 2a side, the light path is indicated by an arrow in FIG. As described above, a light reflection state can be realized. Further, when the shape anisotropic member 10 is oriented on the same plane, the brightest (highest light utilization efficiency) light reflection state is obtained.

In the light modulation device of the second embodiment, the liquid crystal and the shape anisotropic member 10 included in the light modulation layer 3 are attached to the back side and the observation surface side of the light modulation device 1b, and the polarizing plate on the observation surface side ( When the transmission axis of the second polarizing plate) is rotated with respect to the transmission axis of the back side polarizing plate (first polarizing plate), the light transmittance near the surface of the shape anisotropic member 10 changes, In addition, the light transmittance in the vicinity of the surface of the shape anisotropic member 10 and the light transmittance in a region other than the vicinity of the surface of the shape anisotropic member 10 are combinations of materials. Here, the observation of the light transmittance as described above is performed in the same manner as shown in FIG. 4 except that the light modulation device 1b is used instead of the light modulation device 1a. Realizing a light modulation device in which the dispersibility of the shape anisotropic member 10 is improved by using the light modulation layer 3 including the liquid crystal in which the light transmittance is in the above state and the shape anisotropic member 10. Can do. This effect is particularly remarkable when a flaky member is used as the shape anisotropic member 10.

In the light modulation device of the second embodiment, the liquid crystal molecules 9 are perpendicular to the main surfaces of the first substrate 2a and the second substrate 2b in a region other than the vicinity of the surface of the shape anisotropic member 10. The transmission axis of the first polarizing plate 15a and the transmission axis of the second polarizing plate 15b are attached to crossed Nicols, and the transmission axis of the second polarizing plate 15b is set to the transmission axis of the first polarizing plate 15a. When rotated counterclockwise, if the clockwise direction is positive and the counterclockwise direction is negative, the shape anisotropic member 10 increases the light transmittance near the surface with respect to the positive rotation direction, and in the negative rotation direction. On the other hand, the shape anisotropic member (first shape anisotropic member) in which the light transmittance near the surface decreases, and the light transmittance in the vicinity of the surface decreases with respect to the positive rotation direction, and in the negative rotation direction. On the other hand, there are few of the shape anisotropic members (second shape anisotropic members) whose light transmittance near the surface increases. And wherein one also for the positive and negative direction of rotation, it is preferable that the light transmittance of the region other than the vicinity of the surface of the shape anisotropy member 10 does not change. By using the light modulation layer 3 including the liquid crystal in which the light transmittance is in the above state and the shape anisotropic member 10, a light modulation device in which the dispersibility of the shape anisotropic member 10 is further improved is realized. be able to. This effect is particularly remarkable when a flaky member is used as the shape anisotropic member 10.

The state of light transmittance in the light modulation device of Embodiment 2 has been described above. An example of the alignment state of the liquid crystal molecules 9 and the shape anisotropic member 10 that realize such a state will be described below. FIG. 7 is a schematic diagram illustrating an example of alignment states of liquid crystal molecules and shape anisotropic members in the light modulation device of the second embodiment.

Consider a case where the transmission axis of the first polarizing plate 15a and the transmission axis of the second polarizing plate 15b are attached to crossed Nicols. In FIG. 7, the dotted double arrows indicate the direction of the transmission axis of the first polarizing plate 15 a, the solid double arrows indicate the direction of the transmission axis of the second polarizing plate 15 b, and the transmission axes are orthogonal to each other. Yes. In the following description, the clockwise direction is defined as positive (+) with reference to the azimuth (0 °) of the transmission axis of the second polarizing plate 15b, and the angle and the azimuth of the axis are described. Thus, from the state (cross Nicol state) in which the transmission axis (azimuth: 90 °) of the first polarizing plate 15a and the transmission axis (azimuth: 0 °) of the second polarizing plate 15b are orthogonal to each other, FIG. When the transmission axis of the second polarizing plate 15b is rotated by −15 ° and + 15 ° with respect to the transmission axis of the first polarizing plate 15a as shown in (a) and (b) of FIG. The light transmittance near the surface of the conductive member 10 changes, and the light transmittance near the surface of the shape anisotropic member 10 is different from the light transmittance in other regions. Further, the shape anisotropic member 10 increases the light transmittance near the surface with respect to the positive rotation direction of the second polarizing plate 15b, and decreases the light transmittance near the surface with respect to the negative rotation direction. The light transmittance near the surface decreases with respect to the positive rotation direction of the shape anisotropic member (FIG. 7A) and the second polarizing plate 15b, and the light near the surface with respect to the negative rotation direction. Including a shape anisotropic member (FIG. 7B) in which the transmittance increases, and in a region other than the vicinity of the surface of the shape anisotropic member 10 with respect to the positive and negative rotation directions of the second polarizing plate 15b. The light transmittance does not change. For this reason, the light transmitted through the liquid crystal molecules 9 oriented with respect to the vicinity of the surface of the shape anisotropic member 10 is considered to be elliptically polarized light as shown in (a) and (b) of FIG.

First, the alignment state of the liquid crystal molecules 9 realizing the elliptical polarization state as shown in FIG. 7A will be described with reference to FIG. As shown in FIG. 7C, when the liquid crystal molecules 9 are aligned in parallel to the vicinity of the surface of the shape anisotropic member 10, it can be seen by comparing FIGS. 7A and 7C. In addition, the direction of the refractive index no with respect to the ordinary light of the liquid crystal molecules 9 is inclined by −45 ° and the direction of the refractive index ne with respect to the extraordinary light is inclined by + 45 ° with respect to the transmission axis of the first polarizing plate 15a. As the optical phase difference axis, the no direction of the liquid crystal molecules 9 corresponds to the fast axis, and the ne direction of the liquid crystal molecules 9 corresponds to the slow axis. When the transmission axis of the first polarizing plate 15a and the alignment state of the liquid crystal molecules 9 are in a relationship as shown in FIGS. 7A and 7C, the linearly polarized light transmitted through the first polarizing plate 15a is shaped. When the liquid crystal molecules 9 oriented with respect to the vicinity of the surface of the anisotropic member 10 are transmitted, the light becomes counterclockwise elliptically polarized light as shown in FIG.

Next, the alignment state of the liquid crystal molecules 9 realizing the elliptical polarization state as shown in FIG. 7B will be described with reference to FIG. As shown in FIG. 7D, when the liquid crystal molecules 9 are aligned in parallel to the vicinity of the surface of the shape anisotropic member 10, it can be understood by comparing FIGS. 7B and 7D. In addition, the direction of the refractive index no with respect to ordinary light of the liquid crystal molecules 9 is tilted by + 45 ° and the direction of the refractive index ne with respect to extraordinary light is tilted by −45 ° with respect to the transmission axis of the first polarizing plate 15a. When the transmission axis of the first polarizing plate 15a and the alignment state of the liquid crystal molecules 9 are in a relationship as shown in FIGS. 7B and 7D, the linearly polarized light transmitted through the first polarizing plate 15a is shaped. When the liquid crystal molecules 9 oriented with respect to the vicinity of the surface of the anisotropic member 10 are transmitted, clockwise elliptically polarized light as shown in FIG. 7B is obtained.

From the above, as an example of the orientation state of the shape anisotropic member 10 in the light modulation device of Embodiment 2, the shape anisotropic member 10 rotates clockwise with respect to the transmission axis of the first polarizing plate 15a when no voltage is applied. And a shape anisotropic member (FIG. 7B) oriented perpendicularly to the main surface of the first substrate 2a and the second substrate 2b, and the first polarization A shape-anisotropic member that intersects the transmission axis of the plate 15a counterclockwise at 45 ° and is oriented perpendicularly to the principal surfaces of the first substrate 2a and the second substrate 2b (see FIG. 7 ( d)).

According to the light modulation device of the second embodiment, the liquid crystal molecules 9 are ordered (parallel) with respect to the vicinity of the surface of the shape anisotropic member 10 and the liquid crystal molecules with respect to the vicinity of the surface of the shape anisotropic member 10. 9 is different from the orientation state of the liquid crystal molecules 9 in the region other than the vicinity of the surface of the shape anisotropic member 10 because the orientation state 9 is oriented in a plane perpendicular to the paper surface in FIG. The dispersibility of the adhesive member 10 can be improved. Moreover, the orientation of the shape anisotropic member 10 when no voltage is applied can be improved by improving the dispersibility of the shape anisotropic member 10. When the light modulation device according to the second embodiment is applied to a display device, the light transmittance (in the case of a display device in a transmissive display mode) and the light reflectance (in a reflection display mode) caused by aggregation of shape anisotropic members. In the case of a display device), it is possible to prevent deterioration in display performance such as contrast and response speed.

Note that the light modulation device of the second embodiment controls the transmitted light amount or the reflected light amount by changing the direction of the shape anisotropic member 10 by an electric action. Therefore, unlike a liquid crystal panel using a polarizing plate, it is not necessary to dispose polarizing plates on the back side of the first substrate 2a and the observation surface side of the second substrate 2b in actual use. For this reason, the light modulation device of the second embodiment is excellent in light utilization efficiency.

(2) Manufacturing Process of Light Modulation Device The manufacturing process of the light modulation device of the second embodiment is the same as the manufacturing process of the light modulation device of the first embodiment except for the combination of the material of the liquid crystal and the shape anisotropic member 10. .

[Comparison 1]
Comparative form 1 is a case where the liquid crystal molecules in the light modulation layer are randomly aligned with respect to the vicinity of the surface of the shape anisotropic member.

The structure of the light modulation device according to comparative form 1 will be described below. FIGS. 8A and 8B are schematic cross-sectional views showing the light modulation device of Comparative Example 1. FIG. 8A shows a state when no voltage is applied, FIG. 8B shows a state when a voltage is applied (longitudinal electric field on) c) shows a state when a voltage is applied (lateral electric field is on). FIG. 9 is a schematic plan view showing an electrode structure arranged in the light modulation device of Comparative Embodiment 1. As shown in FIG. 8, the light modulation device 101 includes a first substrate 102a, a light modulation layer 103, and a second substrate 102b in order from the back surface side to the observation surface side. The first substrate 102a and the second substrate 102b are bonded to each other via a sealing material (not shown) arranged so as to surround the display area.

The first substrate 102a includes a support substrate 104a, a pair of

electrodes

105a and 105b, and a vertical alignment film 107a in order from the back surface side to the observation surface side.

The pair of

electrodes

105a and 105b has an IPS-type electrode structure, and specifically, is a pair of comb-teeth electrodes in which mutual comb teeth are fitted. As shown in FIG. 9, each of the

electrodes

105a and 105b has a trunk portion and a plurality of parallel branch portions (comb teeth) extending from the trunk portion. ) Are alternately arranged. As shown in FIG. 8C, a voltage is applied between the electrode 105a and the electrode 105b with an AC power source (AC), whereby a lateral electric field (with respect to the first substrate 102a) is applied to the light modulation layer 103. Parallel electric fields).

The vertical alignment film 107a is disposed so as to cover at least the entire display region. That is, the initial alignment of the liquid crystal molecules 109 in the light modulation layer 103 is set in a direction perpendicular to the first substrate 102a.

The second substrate 102b includes a support substrate 104b, a counter electrode 106, an insulating film 108, and a vertical alignment film 107b in order from the observation surface side to the back surface side.

The counter electrode 106 is arranged in a plane so as to face the pair of

electrodes

105a and 105b and cover the entire display region. As shown in FIG. 8B, a vertical electric field (first substrate) is applied to the light modulation layer 103 by applying a voltage between the

electrodes

105a and 105b and the counter electrode 106 with an AC power supply (AC). 102a and an electric field perpendicular to the second substrate 102b) can be formed.

The vertical alignment film 107b is disposed in the same manner as the vertical alignment film 107a of the first substrate 102a.

The light modulation layer 103 is obtained by dispersing the shape anisotropic member 110 in the liquid crystal.

In the light modulation device of comparative form 1, the shape anisotropic member 110 has liquid crystal molecules 109 aligned randomly with respect to the vicinity of the surface thereof. Further, the shape anisotropic member 110 is oriented perpendicular to the main surfaces of the first substrate 102a and the second substrate 102b when no voltage is applied. The vicinity of the surface of the shape anisotropic member 110 indicates a range within 1 μm from the surface of the shape anisotropic member 110. The main surfaces of the first substrate 102a and the second substrate 102b indicate surfaces on the opposite sides of each other.

In the light modulation device of comparative form 1, since the liquid crystal molecules 109 are randomly aligned with respect to the vicinity of the surface of the shape anisotropic member 110, polarizing plates are attached to the back side and the observation surface side of the light modulation device 101 for observation. When the transmission axis of the polarizing plate on the surface side is rotated with respect to the transmission axis of the polarizing plate on the back side, the light transmittance near the surface of the shape anisotropic member 110 does not change. The light transmittance as described above is observed in a state as shown in FIG. FIG. 10 is a schematic cross-sectional view illustrating a state in which light transmittance is observed with respect to the light modulation device according to the first comparative embodiment. As shown in FIG. 10, the light transmittance is observed using a polarizing microscope. A first polarizing plate 115 a is attached to the back side of the light modulation device 101, and a second light is observed on the observation surface side of the light modulation device 101. The polarizing plate 115b is attached, and the transmission axis of the second polarizing plate 115b is rotated with respect to the transmission axis of the first polarizing plate 115a. Specifically, the light modulation device 101 is placed on the stage of a polarizing microscope, the orientation of the transmission axis of the polarizer (corresponding to the first polarizing plate 115a), and the analyzer (on the second polarizing plate 115b). The transmission axis of the analyzer is set to have a predetermined relationship (for example, crossed Nicols (orthogonal state)), and the transmission axis of the analyzer is rotated with respect to the transmission axis of the polarizer in transmission observation. Thus, the method is performed by observing the vicinity of the surface of the shape anisotropic member 110 and the vicinity thereof. A general instrument can be used as the polarizing microscope.

As described above, the state of light transmittance in the light modulation device of the comparative form 1 has been described. The alignment state of the liquid crystal molecules 109 and the shape anisotropic member 110 that realize such a state will be described below. FIG. 11 is a schematic diagram for explaining the alignment state of the liquid crystal molecules and the shape anisotropic member in the light modulation device of Comparative Embodiment 1. FIG. 11 corresponds to a state (plan view) when the state shown in FIG. 10 is viewed from the observation surface side.

Consider a case where the transmission axis of the first polarizing plate 115a and the transmission axis of the second polarizing plate 115b are attached to crossed Nicols. In FIG. 11, the dotted double arrows indicate the orientation of the transmission axis of the first polarizing plate 115 a, the solid double arrows indicate the orientation of the transmission axis of the second polarizing plate 115 b, and the transmission axes are orthogonal to each other. Yes. In the following, the angle and the axis direction are described by defining the clockwise direction as positive (+) with respect to the direction (0 °) of the transmission axis of the second polarizing plate 115b. Thus, from the state (cross Nicol state) in which the transmission axis (azimuth: 90 °) of the first polarizing plate 115a and the transmission axis (azimuth: 0 °) of the second polarizing plate 115b are orthogonal to each other, FIG. As shown in FIG. 4, when the transmission axis of the second polarizing plate 115b is rotated by −15 ° and + 15 ° with respect to the transmission axis of the first polarizing plate 115a, the light near the surface of the shape anisotropic member 110 The transmittance does not change. For this reason, the light transmitted through the liquid crystal molecules 109 oriented with respect to the vicinity of the surface of the shape anisotropic member 110 is considered to be non-polarized light (a collection of various polarization states) as shown in FIG. As the alignment state of the liquid crystal molecules 109 realizing the non-polarized state as shown in FIG. 11, a state where the liquid crystal molecules 109 are randomly aligned with respect to the vicinity of the surface of the shape anisotropic member 110 is considered. Regardless of the position where the transmission axis of the plate 115b is rotated, it is considered that light is transmitted to the same extent.

According to the light modulation device of comparative form 1, since the liquid crystal molecules 109 are randomly aligned with respect to the vicinity of the surface of the shape anisotropic member 110, the dispersibility of the shape anisotropic member cannot be improved. The anisotropic member 110 tends to aggregate. Further, since the shape anisotropic member 110 is likely to aggregate, the orientation of the shape anisotropic member 110 when no voltage is applied deteriorates. When the light modulation device of comparative form 1 is applied to a display device, light transmittance (in the case of a display device in transmissive display mode), light reflectance (reflection display mode) due to aggregation of shape anisotropic members Display performance), display performance such as contrast and response speed deteriorates.

Below, the comparative example regarding the optical modulation apparatus of the comparative form 1 is shown. In the following comparative examples, a flake-shaped member was used as the shape anisotropic member 110.

(Comparative Example 1)
Comparative Example 1 is a case where the shape anisotropic member 110 has a polymer layer on the outer surface, and the polymer layer covers a core portion of the shape anisotropic member 110; and In this case, the coating layer has a two-layer structure composed of a surface modification layer for modifying the surface. The manufacturing process of the light modulation device of Comparative Example 1 was as follows.

(A) Preparation of the mixture The shape anisotropic member 110, the liquid crystal, and plastic beads for controlling the thickness of the light modulation layer 103 were mixed and subjected to ultrasonic irradiation for 60 minutes to prepare a mixture. As the shape anisotropic member 110, an aluminum flake as a core portion, a silica-based insulator A1 as a coating layer, and a hydrophobically treated polymer B3 as a surface modification layer are used, and the average thereof is used. The particle size was 7 μm. The shape anisotropic member 110 used was washed in advance. As a cleaning method, first, the operation of performing centrifugation after repeating the ultrasonic irradiation with IPA added is repeated three times, and then performing the centrifugal separation after performing the ultrasonic irradiation with adding acetone. The operation was repeated three times, and finally the method of natural drying was used. The mixing amount of the shape anisotropic member 110 was 10 wt% with respect to the liquid crystal. As the liquid crystal, a fluorine-based liquid crystal (Δε = 20.4) manufactured by Merck & Co. was used. As the plastic beads, plastic beads (trade name: Micropearl) manufactured by Sekisui Chemical Co., Ltd. were used, and the average particle size was 10 μm. The mixing amount of the plastic beads was 0.2 wt% with respect to the liquid crystal.

(B) Formation of Light Modulation Layer After the mixture was dropped onto the first substrate 102a, the light modulation layer 103 was formed by bonding the first substrate 102a and the second substrate 102b in the air. The thickness of the light modulation layer 103 was 10 μm. In the first substrate 102a, the pair of

electrodes

105a and 105b was made of ITO, the electrode width was 10 μm, the electrode interval (space) was 10 μm, and the thickness was 100 nm. In the second substrate 102b, the counter electrode 106 is made of ITO and has a thickness of 100 nm. The material for the insulating film 108 is an overcoat material (dielectric constant εr = 3.4) used as a color filter manufactured by Toppan Printing Co., Ltd., and the thickness was 3 μm. As the

vertical alignment films

107a and 107b, an alignment film (trade name: SE-4811, surface free energy: 35.0) manufactured by Nissan Chemical Industries, Ltd. was used, and the thickness thereof was 100 nm. Thus, the light modulation device 101 is completed. In such a configuration, the liquid crystal molecules 109 are randomly aligned with respect to the vicinity of the surface of the shape anisotropic member 110, and the dispersibility of the shape anisotropic member 110 cannot be improved.

[Evaluation results]
For the light modulation devices of Examples 1, 2, 9 and Comparative Example 1, (A) observation of the light transmission state and (B) switching operation evaluation with or without voltage application were performed.

(A) Observation of light transmission state FIG. 12 is a photograph showing the observation results of the light transmission state of the light modulation devices of Examples 1, 2, and 9. FIG. 13 is a photograph showing an observation result of a light transmission state of the light modulation device of Comparative Example 1. 12 and 13 show the state when no voltage is applied. As an observation method of the light transmission state, as described with reference to FIGS. 4 and 10, the transmission axis (azimuth: 90 °) of the first polarizing plate 15a (115a) and the second polarizing plate 15b. From the state (cross Nicol state) in which the transmission axis (azimuth: 0 °) of (115b) is orthogonal, the transmission axis of the second polarizing plate 15b (115b) is the transmission axis of the first polarizing plate 15a (115a). On the other hand, a method of rotating from −15 ° to + 15 ° and observing from the side opposite to the light modulation device of the second polarizing plate 15b (115b) was adopted. “−15 °”, “0 °”, and “+ 15 °” in FIGS. 12 and 13 indicate the rotation angle of the transmission axis of the second polarizing plate 15b (115b). “Bright” in FIG. 12 indicates a state in which the light transmittance is increased with respect to the crossed Nicol state (0 °), and “Dark” indicates that the light transmittance is decreased with respect to the crossed Nicol state (0 °). Indicates the state.

As shown in FIG. 12, in the light modulation devices of Examples 1, 2, and 9, with the rotation of the transmission axis of the second polarizing plate 15b, the amount of light leakage near the surface of the shape anisotropic member 10, That is, the light transmittance was changed, and the light transmittance near the surface of the shape anisotropic member 10 was different from the light transmittance in other regions. Furthermore, the shape anisotropic member 10 increases the light transmittance near the surface with respect to the positive rotation direction (from 0 ° to + 15 °) of the second polarizing plate 15b, and the negative rotation direction (from 0 °). Shape anisotropic members 10a (Example 1), 10c (Example 2), 10e (Example 9) in which the light transmittance in the vicinity of the surface decreases with respect to −15 °) and the second polarizing plate 15b Shape anisotropic members 10b (Example 1), 10d (Example) in which the light transmittance near the surface decreases with respect to the positive rotation direction of the light and the light transmittance near the surface increases with respect to the negative rotation direction. 2) 10f (Example 9), and the light transmittance of the region other than the vicinity of the surface of the shape anisotropic member 10 did not change with respect to the positive and negative rotation directions of the second polarizing plate 15b. On the other hand, as shown in FIG. 13, in the light modulation device of Comparative Example 1, with the rotation of the transmission axis of the second polarizing plate 115b, the amount of light leakage near the surface of the shape anisotropic member 110, that is, The light transmittance did not change.

(B) Evaluation of switching operation with and without voltage application FIG. 14 is a photograph showing the results of switching operation evaluation for the light modulation devices of Examples 1, 2, and 9. FIG. 15 is a photograph showing switching operation evaluation results for the optical modulation device of Comparative Example 1. As an evaluation method of the switching operation, from the time of no voltage application (lateral electric field off) as described with reference to FIGS. 1A and 1C and FIG. 8A and FIG. A method of observing the orientation state of the shape anisotropic member 10 (110) in a state where the switching operation was performed during voltage application (transverse electric field on) was adopted. The applied voltage was an AC voltage having a Vpp of 10 V and a period of 33.4 msec, and was applied to the electrode 5b (105b).

As shown in FIGS. 14 and 15, the light modulating devices of Examples 1, 2, and 9 are comparative examples 1 in spite of the same amount of shape anisotropic member being dispersed in the liquid crystal. Compared with the light modulation device, the dispersibility of the shape anisotropic member 10 was good. Therefore, in the light modulation devices of Examples 1, 2, and 9, the shape anisotropic member 10 was uniformly switched by voltage application, and a good light transmission state and light reflection state could be realized. The dispersibility of the shape anisotropic member 10 was improved in the order of Example 9, Example 1, and Example 2, and was particularly excellent in the light modulation device of Example 2. On the other hand, as shown in FIG. 15, in the light modulation device of Comparative Example 1, the dispersibility of the shape anisotropic member 110 is poor and there are aggregated portions (portions surrounded by dotted lines in FIG. 15). It was. Therefore, in the light modulation device of Comparative Example 1, the shape anisotropic member 110 does not perform a uniform switching operation due to voltage application, and the operation performance is poor.

[Appendix]
Examples of preferred embodiments of the light modulation device of the present invention are given below. Each example may be appropriately combined without departing from the scope of the present invention.

The liquid crystal molecules in the liquid crystal are aligned perpendicular to the main surfaces of the first substrate and the second substrate in a region other than the vicinity of the surface, and the transmission axis of the first polarizing plate, and When the transmission axis of the second polarizing plate is attached to crossed Nicols and the transmission axis of the second polarizing plate is rotated with respect to the transmission axis of the first polarizing plate, the clockwise direction is positive or counterclockwise. Is negative, the shape anisotropic member has a first shape in which the light transmittance near the surface increases in the positive rotation direction and the light transmittance near the surface decreases in the negative rotation direction. Among the anisotropic member and the second shape anisotropic member in which the light transmittance near the surface decreases with respect to the positive rotation direction and the light transmittance near the surface increases with respect to the negative rotation direction. The light transmittance of the region other than the vicinity of the surface does not change with respect to the positive and negative rotation directions. It may be. Thereby, the light modulation device in which the dispersibility of the shape anisotropic member is further improved can be realized. Here, the shape anisotropic member preferably includes at least one of the first shape anisotropic member and the second shape anisotropic member. From the viewpoint of further improving the properties, it is more preferable that both the first shape anisotropic member and the second shape anisotropic member are included.

The shape anisotropic member is aligned perpendicular to the main surfaces of the first substrate and the second substrate, and the liquid crystal molecules are aligned perpendicular to the surface vicinity of the shape anisotropic member. You may do. Thereby, the dispersibility of the shape anisotropic member can be further improved.

The shape anisotropic member may have a polymer layer on the outer surface. Thereby, the liquid crystal molecules can be suitably ordered in the vicinity of the surface of the shape anisotropic member.

The polymer layer may include a first polymer layer and a second polymer layer that surface-modifies the first polymer layer. As a result, the first polymer layer does not leave the shape anisotropic member, and the polymer forming the second polymer layer is a polymer that forms the first polymer layer. Since the second polymer layer is not detached from the first polymer layer by polymerization, the shape anisotropic member can be effectively used.

The shape anisotropic member may be a metal flake. Thereby, the light reflection state can be suitably realized by utilizing the effect of reflecting light by the shape anisotropic member.

The first polymer layer is formed by polymerizing a monomer having an ethylenically unsaturated group, and has a monomer having two or more ethylenically unsaturated groups as a constituent component. The second polymer layer containing at least 5% by weight is represented by the general formula R1SiX ₃ (R1 represents an alkyl group having 1 to 21 carbon atoms. X represents a halogen atom or an alkoxy group having 1 to 4 carbon atoms. It may be formed from an organosilane compound represented by. Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The first polymer layer is formed by polymerizing a monomer having an ethylenically unsaturated group, and has a monomer having two or more ethylenically unsaturated groups as a constituent component. comprises at least 5 wt%, the second polymer layer has the general formula R1SiX ₃ (R1 is .X which represents a linear alkyl group having 1 to 21 carbon atoms, a chlorine atom, odor atom, a methoxy group, or , Which represents an ethoxy group). Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The monomer having two or more ethylenically unsaturated groups is Y-methylolalkyl Z (meth) acrylate (Y and Z are integers satisfying Y ≧ Z ≧ 2), polyoxyalkylene glycol diester. It may be at least one monomer selected from the group consisting of (meth) acrylate, triallyl (iso) cyanurate, triallyl trimellitate, divinylbenzene, diallyl phthalate, and diallylacrylamide. Thereby, said 1st polymer layer can be utilized more effectively.

The first polymer layer has a first functional group, and the second polymer layer has a long-chain alkyl group and a second functional group capable of reacting with the first functional group. You may have. Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The first functional group and the second functional group may form a covalent bond. Thereby, said 1st polymer layer and said 2nd polymer layer can be utilized more effectively.

The long chain alkyl group may be bonded to a graft polymer chain graft-polymerized on the surface of the first polymer layer. The long chain alkyl group may have 6 or more carbon atoms. Thereby, said 1st polymer layer and said 2nd polymer layer can be utilized more effectively.

The first polymer layer has at least one of a functional group capable of radical chain transfer and an active group having radical polymerization initiating ability, and the second polymer layer has a long-chain alkyl group. It may have a graft polymer chain. As a result, since the coverage of the polymer layer is increased, the liquid crystal molecules can be aligned perpendicular to the vicinity of the surface of the shape anisotropic member, thereby preventing aggregation of the shape anisotropic member. , The dispersibility can be improved.

The second polymer layer may be an aluminum alkoxide polycondensate that forms an aluminosilicate bond, an aluminotitanate bond, or an aluminosirconate bond with the first polymer layer. The first polymer layer may be formed from a plastic material. Thereby, since the second polymer layer has hydrophilicity, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, and aggregation of the shape anisotropic member can be performed. And the dispersibility can be improved.

The first polymer layer is formed from silica, and the second polymer layer is represented by the general formula R1SiX ₃ (R1 represents an alkyl group having 1 to 21 carbon atoms. X is a halogen atom. It may be formed from an organic silane compound represented by the following: an atom or an alkoxy group having 1 to 4 carbon atoms. Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The first polymer layer is formed from silica, and the second polymer layer is represented by the general formula R2SiX ₃ (R2 represents a group having a dipole moment of 1 to 5 Debye. X represents And a halogen atom or an alkoxy group having 1 to 4 carbon atoms). Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The first polymer layer is formed from silica, and the second polymer layer is represented by the general formula R1SiX ₃ (R1 represents an alkyl group having 1 to 21 carbon atoms. X is a halogen atom. And an organic silane compound represented by the general formula R2SiX ₃ (R2 represents a group having a dipole moment of 1 to 5 Debye. X is a halogen atom or It may be formed from a mixture with an organic silane compound represented by (C 1 -C 4 alkoxy group). Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The polymer layer includes at least one of an ethylene glycol polymer having a weight average molecular weight of 10,000 or more and 1,000,000 or less and a propylene glycol polymer having a weight average molecular weight of 10,000 or more and 1,000,000 or less. There may be. Thereby, since the alignment regulating force for the liquid crystal molecules is weakened, the liquid crystal molecules can be aligned perpendicular to the vicinity of the surface of the shape anisotropic member, preventing aggregation of the shape anisotropic member, The dispersibility can be improved.

The polymer layer may contain a nonylphenol ethylene oxide adduct. The abundance of the nonylphenol ethylene oxide adduct may be 2% by weight or more and 80% by weight or less, assuming that the amount present on the entire surface of the shape anisotropic member is 100% by weight. Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The polymer layer includes a crosslinkable monomer having two or more ethylenically unsaturated groups, at least one of a fluorine-based monomer and a monomer having a glycidyl group, and a monomer having ethylene glycol. It may be formed from a copolymer. The crosslinkable monomer having two or more ethylenically unsaturated groups is 20 to 96% by weight based on 100% by weight of the polymer layer, and at least one of the fluorine monomer and the monomer having a glycidyl group. One may be 2 to 78% by weight, and the monomer having ethylene glycol may be 2 to 78% by weight. Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

The polymer layer may have a glycidyl group. The surface area occupied by the component containing the glycidyl group may be 10% or more and 80% or less with respect to the total surface area of the shape anisotropic member. Thereby, the liquid crystal molecules can be aligned perpendicularly to the vicinity of the surface of the shape anisotropic member, the aggregation of the shape anisotropic member can be prevented, and the dispersibility thereof can be improved.

Below, the example of the preferable aspect of the manufacturing method of the light modulation apparatus of this invention is given. Each example may be appropriately combined without departing from the scope of the present invention.

The manufacturing method of the light modulation device may include a step of coating the outer surface of the shape anisotropic member with a polymer layer before the step (1). Thereby, the said shape anisotropic member which orientates the said liquid-crystal molecule | numerator suitably orderly with respect to the surface vicinity can be obtained.

Below, the example of the preferable aspect of the display apparatus of this invention is given. Each example may be appropriately combined without departing from the scope of the present invention.

The display device has a light source on the back side of the light modulation device, a reflective display mode in which display is performed by reflecting external light by the shape anisotropic member, and light emitted from the light source is transmitted and displayed. The transmissive display mode for performing the switching may be switchable. Thereby, a display device in a transflective display mode (a combination of the reflective display mode and the transmissive display mode) can be realized.

1a, 1b, 101:

light modulation device

2a, 102a:

first substrate

2b, 102b: second substrate 3, 103:

light modulation layers

4a, 4b, 104a, 104b:

support substrates

5a, 5b, 105a, 105b: Electrodes 6, 106:

counter electrodes

7a, 7b, 107a, 107b: vertical alignment film 8, 108: insulating film 9, 109:

liquid crystal molecules

10, 10a, 10b, 10c, 10d, 10e, 10f, 110: shape anisotropy Member 11: Core part 12: Polymer layer 13: Coating layer 14:

Surface modification layer

15a, 115a:

First polarizing plate

15b, 115b: Second polarizing plate AC: AC power source

Claims

In order from the back side to the observation side,
First substrate,
A light modulation layer, and
A light modulation device comprising a second substrate,
The light modulation layer is obtained by dispersing a shape anisotropic member in liquid crystal,
A first polarizing plate is attached to the back side of the light modulation device, a second polarizing plate is attached to the observation surface side of the light modulation device, and the transmission axis of the second polarizing plate is the same as that of the first polarizing plate. When rotated with respect to the transmission axis, the light transmittance in the vicinity of the surface of the shape anisotropic member changes, and the light transmittance in the vicinity of the surface and the light transmittance in a region other than the vicinity of the surface are different. An optical modulation device characterized by that.
The liquid crystal molecules in the liquid crystal are aligned perpendicular to the principal surfaces of the first substrate and the second substrate in a region other than the vicinity of the surface,
The transmission axis of the first polarizing plate and the transmission axis of the second polarizing plate are attached to crossed Nicols, and the transmission axis of the second polarizing plate is rotated with respect to the transmission axis of the first polarizing plate. When the clockwise direction is positive and the counterclockwise direction is negative, the shape anisotropic member has an increased light transmittance near the surface with respect to the positive rotation direction and the surface with respect to the negative rotation direction. The first shape anisotropic member with reduced light transmittance in the vicinity and the light transmittance near the surface with respect to the positive rotation direction, and the light transmittance near the surface with respect to the negative rotation direction Including at least one of the second shape anisotropic member
The light modulation device according to claim 1, wherein the light transmittance in a region other than the vicinity of the surface does not change with respect to positive and negative rotation directions.
The shape anisotropic member is oriented perpendicular to the main surfaces of the first substrate and the second substrate,
The light modulation device according to claim 2, wherein the liquid crystal molecules are aligned perpendicular to the vicinity of the surface of the shape anisotropic member.
The light modulation device according to any one of claims 1 to 3, wherein the shape anisotropic member has a polymer layer on an outer surface.
5. The light modulation device according to claim 4, wherein the polymer layer includes a first polymer layer and a second polymer layer that modifies the surface of the first polymer layer.
The light modulation device according to any one of claims 1 to 5, wherein the shape anisotropic member is a thin piece of metal.
A method for manufacturing a light modulation device according to any one of claims 1 to 6,
Producing a mixture in which the shape anisotropic member is dispersed in the liquid crystal (1); and
Step (2) of disposing the mixture between the first substrate and the second substrate to form the light modulation layer
The manufacturing method of the light modulation apparatus characterized by the above-mentioned.
The light modulation device according to claim 7, wherein the method for manufacturing the light modulation device includes a step of coating an outer surface of the shape anisotropic member with a polymer layer before the step (1). Device manufacturing method.
A display device comprising the light modulation device according to any one of claims 1 to 6.
The display device includes a light source on the back side of the light modulation device, a reflective display mode in which display is performed by reflecting external light by the shape anisotropic member, and light emitted from the light source is transmitted and displayed. The display device according to claim 9, wherein the display device is switchable between a transmissive display mode and a transmissive display mode.