JPH11237612A - High polymer dispersed liquid crystal element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain the high reflectivity of a PDLC(polymer dispersed liquid crystal) element having a multilayered sturcure which compares a composite structure of a high-polymer compd. and low-polymer liquid crystals and of which the reflective index changes periodically therein. SOLUTION: A polymerizable compsn. 3 contg. at least the polymerizable compd. having diazo dyestuff molecular side chains, the low-polymer liquid crystals and a polymn. initiator of a polymerizable group is injected into a cell. This cell is irradiated with laser beams 4a, 4b to cues the interference of the laser beams 4a, 4b in the polymerizable compsn. 3. In the regions where amplitude of laser interference hght is large, the polymerable compass, are polymerized and cured, by which light polymer layers 5 are formed. In the regions where the amplitude of laser interference light is small, a phase sepn. occurs and PDLC layers 6 are formed. The cell is irradiated with the polarized light 8 having the polarization axis 8a of the linearly polarized light with in the plane parallel with the substrate plane. As a result, the diazo dyestuff molecular side chains at the boundary of the liquid region 7 and the high polymer region are curved to the direction perpendicular to the polarization axis 8a of the polarized light 8 and the liquid crystal molecules 7a in the liquid crystal region 7 are aligned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer dispersed liquid crystal element which can be used as a display element, a light control element, a light modulation element, and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a display element or a dimming element, a polymer dispersed liquid crystal (Polymer Dispersed Liquid) in which a liquid crystal is dispersed in voids of a polymer having a three-dimensional structure.
(Crystal) is known. Hereinafter, the polymer dispersed liquid crystal is referred to as PDLC, and the polymer dispersed liquid crystal element is also referred to as PDLC element.

FIG. 8 shows an example of this PDLC element.
A PDLC layer 16 in which a liquid crystal region (liquid crystal droplet) 7 is dispersed in a polymer region 15 is formed between an electrode 2a on the substrate 1a and an electrode 2b on the substrate 1b.

In this PDLC element, electrodes 2a,
When no voltage is applied between 2b, as shown in FIG. 3A, the liquid crystal molecules 7a in the liquid crystal region 7 are oriented in a random direction, thereby causing a difference in the refractive index between the liquid crystal and the polymer. Incident light 11 is refracted at the interface between the liquid crystal and the polymer, and P
In the entire DLC layer 16, the incident light 11 passes through a large number of liquid crystal regions 7 and is in a scattering state.

When a voltage is applied between the electrodes 2a and 2b, the liquid crystal molecules 7a in the liquid crystal region 7 are oriented perpendicular to the substrate surface as shown in FIG. By keeping the index equal to the refractive index of the polymer,
The PDLC layer 16 becomes transparent, and the incident light 11 transmits through the PDLC layer 16 as transmitted light 13.

This polymer-dispersed liquid crystal element does not require a polarizing plate, so that bright display is expected, and its application to a projector light valve or the like is considered.

As a composite structure of a polymer and a liquid crystal, a structure in which liquid crystal is distributed independently of each other and a structure in which liquid crystal is continuously distributed are considered. Broadly speaking, the following three methods have been proposed for producing a composite film.

The first method is to impregnate a liquid crystal into a porous polymer capable of randomly aligning the liquid crystal. The second is a method in which a polymer and a liquid crystal are mixed and emulsified in a solvent, and then the solvent is evaporated to cure the polymer. Third, a polymerizable composition obtained by mixing a liquid crystal with a monomer or oligomer, or a mixture thereof,
By applying heat or irradiating with ultraviolet rays,
In this method, a polymer is polymerized and a polymer and a liquid crystal are phase-separated.

As another example of this PDLC, SPLC
IE. 1080, 83, (1989) show a PDLC element in which the refractive index periodically changes.

[0010] Specifically, as shown in FIG.
Between the upper electrode 2a and the electrode 2b on the substrate 1b, a polymer layer 18 mainly composed of a polymer and a PDLC layer 19 in which the liquid crystal region 7 is dispersed in the polymer region are alternately formed in multiple layers. To form a structure in which the refractive index changes periodically.

In this PDLC element, the electrodes 2a,
When no voltage is applied between 2b, polymer layer 18 and PD
The specific wavelength component in the incident light 11 is reflected as the reflected light 12 by the periodic change of the refractive index by the LC layer 19 and the principle of the interference filter as shown in FIG.

When a voltage is applied between the electrodes 2a and 2b, as shown in FIG. 1B, the liquid crystal molecules 7a in the liquid crystal region 7 are oriented perpendicular to the substrate surface, and the liquid crystal molecules 7a are refracted in the major axis direction. By making the refractive index equal to the refractive index of the polymer, the periodic change in the refractive index caused by the polymer layer 18 and the PDLC layer 19 disappears, and the incident light 11 is mostly transmitted light 1
As 3, pass through the cell.

[0013]

The PDLC element shown in FIG. 9 is expected to provide a high reflectance and a bright display by the principle of the interference filter.

However, in the PDLC element shown in FIG.
When no voltage is applied between the electrodes 2a and 2b, the liquid crystal molecules 7a in the liquid crystal region 7 are oriented in random directions, so that the difference in the refractive index between the polymer layer 18 and the PDLC layer 19 is small. Does not provide high reflectivity.

That is, at this time, since the orientation of the liquid crystal molecules 7a in the liquid crystal region 7 is random in the entire PDLC layer 19, the refractive index na of the PDLC layer 19 is
First-order approximated refractive index (ne + 2no) / 3, PDL
From the refractive index np of the polymer in the C layer 19 and the volume fraction v of the liquid crystal in the PDLC layer 19 with respect to the polymer, na = {no (3-v) + ne} / 3 (1) Value. Here, ne is the refractive index of the liquid crystal with respect to extraordinary light, and no is the refractive index of the liquid crystal with respect to normal light.

Therefore, the polymer layer 18 and the PDLC layer 19
Is small, and a high reflectance cannot be obtained.

As shown in FIG. 9, in a liquid crystal device having a multi-layer structure in which the PDLC is composed of a polymer and a liquid crystal and the refractive index of which is periodically changed, the liquid crystal in the specific direction is changed. If it can be oriented to, the difference in the refractive index between the polymer layer and the PDLC layer, or the change in the internal periodic refractive index can be increased,
High reflectivity can be obtained.

In the PDLC element, as described below, it has been considered to control the alignment direction of the liquid crystal in the initial state.

(1) US Pat. No. 5,188,760 discloses that a liquid crystal monomer is used to inject a polymerizable composition as a precursor of PDLC into a cell with an alignment film, and to irradiate ultraviolet rays and heat. By addition, the liquid crystalline polymer, which is a polymer of the liquid crystalline monomer, and the low-molecular liquid crystal are polymerized and phase separated while being oriented in the direction of the alignment film. A way to be done is shown.

(2) Japanese Patent Application Laid-Open No. 5-281527 discloses that a polymerizable composition is injected into a cell having no alignment film, and an ultraviolet or By applying heat, a method is shown in which the low-molecular liquid crystal is oriented in the direction of an external field to perform polymerization phase separation, and after the polymerizable composition is cured, the orientation of the low-molecular liquid crystal is fixed. .

(3) "Japan Display '9"
2.699 ”, a polymerizable composition that is a precursor of PDLC is prepared so as to have a liquid crystal phase having a very high liquid crystal concentration, and is injected into a cell with an alignment film (in this state, the liquid crystal phase state). The polymerizable composition is oriented in the direction of the alignment film), and a method of fixing the orientation of the low-molecular liquid crystal in the initial orientation state by applying ultraviolet light or heat to cause a polymerization phase separation.

(4) "Mol. Mat., 2,295
(1993) ", first, a composite film comprising a polymer compound having a diazo dye molecule side chain and a poor solvent of the polymer compound was prepared by an emulsification method, and then the poor solvent was removed from the composite film. Extraction and drying of the composite film to produce a porous polymer composed of a polymer compound having a diazo dye molecule side chain, and then impregnating the porous polymer with a low-molecular liquid crystal to form a diazo dye molecule side chain Then, a PDLC made of a polymer compound having the following formula is produced. Then, the PDLC is irradiated with polarized light to cause a light dimerization reaction. With the structural change of the polymer compound due to the light dimerization reaction, a low molecular weight compound is formed. A method for aligning the liquid crystal is shown.

However, in the methods (1) and (3),
Since the alignment of the liquid crystal is controlled by the alignment film, a multilayer structure in which the refractive index periodically changes as shown in FIG. 9 cannot be formed.

In the method (2), since a magnetic field or an electric field is applied in parallel with the cell, when the cell size is large, it is difficult to apply an effective external field over the entire surface of the cell. . For example, in Japanese Patent Application Laid-Open No. 5-281527,
When an external electric field is applied, the magnitude of the electric field is 1 kV / c
It is described that m or more is necessary. But diagonal 1
Assuming a cell size of 2 inches, the applied voltage is about 35
The calculation requires 0 kV or more, and such a large applied voltage cannot be easily realized.

Further, in the method (4), the element can be manufactured only by the impregnation method. However, in the impregnation method,
As shown in FIG. 9, a multilayer structure in which the refractive index periodically changes cannot be formed.

In short, in the conventional method, it is impossible to obtain a high reflectivity in a PDLC element having a multilayer structure in which a polymer compound and a low-molecular liquid crystal are combined and a refractive index periodically changes inside. Can not.

Accordingly, the present invention relates to a PDLC element having a multilayer structure composed of a composite structure of a polymer compound and a low-molecular liquid crystal and having a periodically changing refractive index inside.
A high reflectance is obtained and a bright display is obtained.

[0028]

The polymer-dispersed liquid crystal element of the present invention is composed of a composite structure of a polymer compound and a low-molecular liquid crystal, and has a multilayer structure in which the refractive index changes periodically inside. In the dispersion liquid crystal element, the polymer compound has a diazo dye molecule side chain that is isomerized in a predetermined direction by irradiation of linearly polarized light, and the low-molecular liquid crystal has a predetermined diazo dye molecule side chain according to the isomerized diazo dye molecule side chain. Orientation.

[0029]

When a diazo dye molecule side chain is irradiated with linearly polarized visible light, the diazo dye molecule has a property of isomerizing into a cis structure in which the molecule is bent in a direction perpendicular to the deflection axis.

Therefore, in a polymer dispersed liquid crystal device having a multilayer structure having a composite structure of a polymer compound and a low-molecular liquid crystal and having a periodically changing refractive index inside, the polymer compound is used in the diazo dye molecule side. By irradiating the polymer-dispersed liquid crystal element with linearly polarized light as having a chain, the diazo dye molecule side chains in the polymer compound are isomerized in a predetermined direction perpendicular to the deflection axis of the polarized light. The liquid crystal molecules inside are also aligned in a predetermined direction.

According to the present invention, based on such a principle, a composite structure of a polymer compound and a low-molecular liquid crystal is provided.
In a polymer dispersed liquid crystal device having a multilayer structure in which a refractive index periodically changes inside, a polymer compound has a diazo dye molecule side chain isomerized in a predetermined direction by irradiation of linearly polarized light, and has a low molecular weight. It is assumed that the liquid crystal is oriented in a predetermined direction by the isomerized diazo dye molecule side chains.

Therefore, in the polymer-dispersed liquid crystal device of the present invention, in the initial state where no electric field or magnetic field is applied thereto, the liquid crystal molecules in the liquid crystal region dispersed in the polymer region are not in a random direction. In a predetermined direction, the internal periodic change in the refractive index can be increased, and a high reflectance can be obtained.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 shows a first example of a manufacturing method of the present invention, and FIG. 2 shows a first example of a PDLC element of the present invention obtained by the method. Is shown.

First, as shown in FIG. 1A, a substrate 1a having an electrode 2a formed on one side and a substrate 1b having an electrode 2b formed on one side are placed with the electrodes 2a and 2b inside. Cells are formed facing each other at predetermined intervals. Substrates 1a, 1
b and the electrodes 2a and 2b have a light transmitting property.

Next, the polymerizable composition 3 is injected into the cell. The polymerizable composition 3 is prepared by mixing at least a polymerizable compound having a diazo dye molecule side chain, a low-molecular liquid crystal, and a polymerization initiator for a polymerizable group.

The polymerizable compound having a diazo dye molecule side chain is a compound having a polymerizable acryloyl group or methacryloyl group added to a compound having a diazo dye molecule side chain, and derivatives thereof.

As a diazo dye molecule, when a polymer containing the same is used as an alignment film,
Use a liquid crystal that has the property of planar alignment that aligns the liquid crystal in a direction parallel to the substrate surface, and that has the property of aligning the liquid crystal in a direction that is orthogonal to the axis of deflection by irradiating linearly polarized light with a wavelength that is absorbed by the dye. . As a diazo dye polymer having such properties, for example, FIG.
(B) Molecules as shown in (C) can be used.

The polymerizable composition includes at least a polymerizable composition having a side chain of a diazo dye molecule. In addition, various polymerizable compositions may be used in combination.
It can form a polymer backbone. For example, alkyl acrylate, acrylamide, hydroxy acrylate, alkyl methacrylate,
Methacrylamide, methacrylic acid hydroxy ester,
Vinylpyrrolidone, styrene and its derivatives, acrylonitrile, vinyl chloride, vinylidene chloride, ethylene,
Monofunctional and polyfunctional monomers such as butadiene, isoprene, and vinylpyridine are preferred, and those having a particularly high viscosity are preferred.

The polymerizable composition contains a polymerization initiator using visible light, ultraviolet light, or heat to polymerize the polymerizable compound.

As the low-molecular liquid crystal, various low-molecular liquid crystal materials generally used as an electric field drive type display material such as a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, and a ferroelectric liquid crystal can be used. Specifically, various low-molecular liquid crystal compounds such as biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, terphenyl, biphenylbenzoate, cyclohexylbiphenyl, phenylpyrimidine, cyclohexylpyrimidine, etc. Can be used. These low-molecular liquid crystal compounds, like low-molecular liquid crystal materials generally used,
The compound does not need to be a single composition, and may be a compound composed of a plurality of components.

Next, as shown in FIG.
And laser beams 4a and 4b
And the laser light 4a in the polymerizable composition 3
And 4b interfere.

Thus, in a region where the amplitude of the laser interference light is large, the polymerizable compound is polymerized and cured to form the polymer layer 5 having a low refractive index, and in a region where the amplitude of the laser interference light is small, Phase separation occurs, and a PDLC layer 6 having a liquid crystal region 7 and a high refractive index is formed. Since the area where the amplitude of the laser interference light is large and the area where the laser interference light is small are alternately spatially repeated, the PD whose refractive index periodically changes is
An LC element is manufactured. However, at this stage, the liquid crystal molecules 7a in the liquid crystal region 7 in the PDLC layer 6 are oriented in random directions.

Next, as shown in FIG. 1C, the cell is irradiated with the deflecting light 8 from outside one of the substrates 1a. The deflected light 8 irradiates the substrate surface perpendicularly as a plane wave of linearly polarized light whose deflection axis 8a exists in a plane parallel to the substrate surface.

Thus, in each PDLC layer 6, the diazo dye molecule side chains at the interface between the liquid crystal region 7 and the polymer region are perpendicular to the deflection axis 8a of the deflection light 8 in a plane parallel to the substrate surface. The liquid crystal molecules 7a in the liquid crystal region 7 are aligned along the direction.

Therefore, the PDLC after the irradiation of the deflection light 8
In the element, in the initial state where no voltage is applied between the electrodes 2a and 2b, all the liquid crystal molecules 7a in the PDLC layer 6 are oriented in a predetermined direction in a plane parallel to the substrate surface, and the polymer layer 5 and the PDLC layer 6 And the difference in the refractive index between
A high reflectance can be obtained, and as shown in FIG. 2A, a specific wavelength component in the incident light 11 is reflected as a reflected light 12 with a high reflectance.

When a voltage is applied between the electrodes 2a and 2b, the liquid crystal molecules 7a in the PDLC layer 6 are changed as shown in FIG.
Are oriented perpendicular to the substrate surface, and the refractive index in the major axis direction of the liquid crystal molecules 7a is made equal to the refractive index of the polymer. Most of the incident light 11 is transmitted through the cell as the transmitted light 13 because of the disappearance of the typical change.

Although the wavelength of the deflecting light 8 varies depending on the side chain of the diazo dye molecule, a wavelength of about 450 nm can be used. The irradiation time varies depending on the light intensity and the sensitivity of the side chain of the diazo dye molecule, but is preferably about 1 minute to 120 minutes.

The liquid crystal region 7 is desirably as small as possible in order to reliably align the liquid crystal molecules 7a inside by the isomerized diazo dye molecule side chains. In particular,
The size is smaller than the wavelength of visible light.

As a method for reducing the size of the liquid crystal region 7, a method of increasing the viscosity of the polymerizable composition and using a material having a high polymerization rate such as a polyfunctional acrylic monomer can be used.

[Second Embodiment] FIG. 3 shows a second example of the manufacturing method of the present invention, and FIG. 4 shows a second example of the PDLC element of the present invention obtained thereby.

First, the substrates 1a and 1b are connected to the electrodes 2a and 2b.
The cells are formed by facing each other at a predetermined interval with.
Next, a polymerizable composition prepared by mixing a polymerizable compound having a diazo dye molecule side chain, a low-molecular liquid crystal, and a polymerization initiator of a polymerizable group is injected into this cell as in the example of FIG. .

Next, as shown in FIG. 3 (A), the cells into which the polymerizable composition has been injected are irradiated with ultraviolet rays 9 to polymerize and polymerize the polymerizable compound. Forming a PDLC layer 10 in which liquid crystal regions 7 are dispersed,
A PDLC element as shown in FIG. 8 is formed.

At this stage, the multilayer structure in which the refractive index changes periodically is not formed, and the PDLC layer 10
The liquid crystal molecules 7a in the middle liquid crystal region 7 are oriented in random directions.

Next, as shown in FIG. 3B, the cell is irradiated with deflected light 8 from outside one of the substrates 1a. The deflected light 8 irradiates the substrate surface perpendicularly as a plane wave of linearly polarized light whose deflection axis 8a exists in a plane parallel to the substrate surface.

As a result, in the PDLC layer 10, the diazo dye molecule side chains at the interface between the liquid crystal region 7 and the polymer region are in a direction perpendicular to the deflection axis 8 a of the deflection light 8 in a plane parallel to the substrate surface. The liquid crystal molecules 7a in the liquid crystal region 7 are oriented along the bending.

Therefore, after the irradiation of the deflecting light 8, the PD
All the liquid crystal molecules 7a in the LC layer 10 are oriented in a predetermined direction in a plane parallel to the substrate surface. However,
Even at this stage, a multilayer structure in which the refractive index changes periodically is not formed.

Next, as shown in FIG.
And laser beams 4a and 4b
And the laser light 4a in the PDLC layer 10
And 4b interfere. However, in this case, it is assumed that each of the laser beams 4a and 4b has a deflection axis orthogonal to the deflection axis 8a of the deflection light 8 irradiated in the step of FIG.

As a result, in the region 10a where the amplitude of the laser interference light is large, the diazo dye molecule side chains at the interface between the liquid crystal region 7 and the polymer region deflect the laser beams 4a and 4b in a plane parallel to the substrate surface. The liquid crystal molecules 7a in the liquid crystal region 7 in the region 10a are bent in a direction perpendicular to the axis, along the direction parallel to the substrate surface in the direction determined by the irradiation of the original polarized light 8. It is oriented in a direction perpendicular to it. Region 1 where the amplitude of laser interference light is small
At 0b, the diazo dye molecule side chains are not isomerized, and thus the orientation direction of the liquid crystal molecules 7a in the liquid crystal region 7 does not change.

The regions 10a and 10b where the amplitude of the laser interference light is large and small are spatially and alternately repeated, so that the polymer layer 5 and the PDLC layer 6 are formed as shown in FIGS. Instead of being alternately repeated,
PDLC having a periodically changing refractive index, in which two kinds of PDLC layers 10a and 10b having different refractive indexes due to different alignment directions of liquid crystal molecules 7a are alternately repeated.
An element is to be manufactured.

The PDLC element of this example has electrodes 2a and 2b
In the initial state where no voltage is applied between the two PDLC layers 10a and 10b, which form a periodic change in the refractive index
Are composed of liquid crystals oriented in directions perpendicular to each other, the periodic change in the refractive index is increased, and a high reflectance is obtained. As shown in FIG. The specific wavelength component in 11 as reflected light 12
Reflect with high reflectance.

When a voltage is applied between the electrodes 2a and 2b, the liquid crystal molecules 7a in the PDLC layer 6 are changed as shown in FIG.
Are oriented perpendicular to the substrate surface, and the refractive index in the major axis direction of the liquid crystal molecules 7a is made equal to the refractive index of the polymer. Most of the incident light 11 is transmitted through the cell as the transmitted light 13 because of the disappearance of the typical change.

[Other Embodiments] As a manufacturing method of the present invention, for example, the following method can be performed in addition to the above-described method.

First, a polymerizable compound having a polymerizable functional group at the terminal of the diazo dye, a polyfunctional acrylic monomer, a low-molecular liquid crystal, and a polymerization initiator for the polymerizable group are mixed to prepare a polymerizable composition. , Injected into the cell. In this case, in order to reduce the size of the liquid crystal region 7, the acrylic monomer is a polyfunctional monomer having a high polymerization rate, and the viscosity of the mixed polymerizable composition is increased.

Further, the cell is irradiated with interference light by laser light. In a region where the amplitude of the laser interference light is large, the diazo dye molecule side chain at the interface between the liquid crystal and the polymer is bent in a direction perpendicular to the deflection axis of the laser light, and the liquid crystal is aligned according to the bending. In a region where the amplitude of the laser interference light is small, the orientation direction remains random. Since the area where the amplitude of the laser interference light is large and the area where the laser interference light is small are alternately spatially repeated, a PDLC element whose refractive index changes periodically can be manufactured.

Example A PDLC device of the present invention was manufactured on a trial basis and its characteristics were measured.

Example 1 In Example 1, the PDLC element shown in FIG. 2 was manufactured by the method shown in FIG.

As the diazo dye monomer, the diazo dye monomer shown in FIG. 5A was synthesized. The polymerizable compound is 80% by weight of dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku) and N vinylpyrrolidone (manufactured by Wako Pure Chemical Industries)
20 wt%. A nematic liquid crystal E7 (manufactured by Merck) was used as the low-molecular liquid crystal.

10% by weight of diazo dye, polymerizable compound 50
wt.% and liquid crystal 40% by weight were mixed, and 5 mM of Rose Bengal (manufactured by Wako Pure Chemical Industries, Ltd.) and 50 mM of N-phenylglycine (manufactured by Wako Pure Chemical Industries, Ltd.) were added as polymerization initiators of the polymerizable compound, and the polymerizable composition The material was prepared.

Two quartz substrates with ITO transparent electrodes were
The prepared polymerizable composition was injected into the cells bonded at a gap of μm.

The 488 nm Ar ion / laser beam was expanded by a beam expander, divided into two light beams, and irradiated into the cell for 10 minutes from the front and back of the cell into which the polymerizable composition was injected. As a result, a PDLC element having a multilayer structure in which the refractive index periodically changes was obtained.

Further, a 488 nm Ar ion / laser beam was irradiated into the cell from one side of the cell with linearly polarized light obtained by enlarging the beam diameter by a beam expander.

(Example 2) In Example 2, the PDLC element of the example shown in FIG. 4 was manufactured by the method of the example shown in FIG.

The same diazo dye monomer, polymerizable compound and low-molecular liquid crystal as in Example 1 were used.
10 wt% of a diazo dye, 50 wt% of a polymerizable compound and 40 wt% of a liquid crystal are mixed, and 5 wt% of Darocur 1173 (manufactured by Nippon Ciba Geigy) as a polymerization initiator for the polymerizable compound.
Was added to prepare a polymerizable composition.

Two quartz substrates with ITO transparent electrodes were
The prepared polymerizable composition was injected into the cells bonded at a gap of μm.

The cell was irradiated with ultraviolet rays of 50 mW using a high-pressure mercury lamp as a light source from one side of the cell into which the polymerizable composition was injected, for 5 minutes to obtain a PDLC element.

Next, a 488 nm Ar ion laser beam was irradiated into the cell from one side of the cell with linearly polarized light obtained by expanding the beam diameter using a beam expander.

Further, an 488 nm Ar ion / laser beam is expanded into two beams after the beam diameter is expanded by a beam expander, and irradiated into the cell from the front and back sides of the cell for 10 minutes, and the refractive index inside the cell is periodically changed. To obtain a PDLC element having a multilayer structure.

(Measurement and Evaluation of Reflection Characteristics) The reflectance of the prepared sample was as shown in FIG.
1. Evaluation optical system 3 in combination with a θ-2θ optical system using a goniometer head and a spectrometer 34
It was measured at zero. That is, white light from the light source 31 was incident on the element of the sample 20 as incident light 32, and reflected light 33 from the sample 20 was measured by a spectrometer 34.

FIG. 7 shows the results of the measurement and evaluation. Here, as a guideline for evaluating the reflectance characteristics of the volume hologram element, “X” indicates a reflectance of 30% or less, “Δ” indicates a reflectance of 30% to 50%, “O” indicates a reflectance of 50% to 70%, and “O” indicates a reflectance of 70% or more. ☆ "
And

As shown in FIG. 7, it can be seen that the reflectance is improved according to the method or device of the present invention.

[0081]

As described above, according to the present invention, there is provided a polymer-dispersed liquid crystal device having a multilayer structure having a composite structure of a polymer compound and a low-molecular liquid crystal and having a periodically changing refractive index inside. , The reflectance can be increased.

According to the invention, such a polymer-dispersed liquid crystal element can be obtained reliably and easily.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a manufacturing method according to the present invention.

FIG. 2 is a diagram showing an example of the polymer-dispersed liquid crystal device of the present invention.

FIG. 3 is a diagram showing another example of the manufacturing method of the present invention.

FIG. 4 is a diagram showing another example of the polymer-dispersed liquid crystal device of the present invention.

FIG. 5 is a diagram showing an example of a diazo dye monomer.

FIG. 6 is a diagram showing an optical system used for measurement evaluation.

FIG. 7 is a diagram showing the results of measurement evaluation.

FIG. 8 is a diagram showing an example of a conventional polymer dispersed liquid crystal element.

FIG. 9 is a diagram showing another example of a conventional polymer dispersed liquid crystal element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1a, 1b Substrate 2a, 2b Electrode 3 Polymerizable composition 4a, 4b Laser beam 5 Polymer layer 6 PDLC layer 7 Liquid crystal region 8 Deflection light 9 Ultraviolet light

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiichi Suzuki 430 Nakai-cho Sakai, Ashigara-gun, Kanagawa Prefecture Inside Green Tech Nakai Fuji Xerox Co., Ltd. 72) Inventor Naoki Hiji 430, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd.

Claims (6)

[Claims] 1. A polymer-dispersed liquid crystal device having a multilayer structure having a composite structure of a polymer compound and a low-molecular liquid crystal and having a periodically changing refractive index inside, wherein the polymer compound has linearly polarized light. Polymer dispersed liquid crystal having a diazo dye molecule side chain isomerized in a predetermined direction by irradiation of light, wherein the low-molecular liquid crystal is oriented in a predetermined direction by the isomerized diazo dye molecule side chain. element. 2. The polymer-dispersed liquid crystal device according to claim 1, wherein the multi-layer structure is formed by alternately stacking polymer layers and polymer-dispersed liquid crystal layers. . 3. The polymer dispersed liquid crystal device according to claim 1, wherein the multilayer structure has two kinds of polymers in which the orientation directions of the low molecular liquid crystals are orthogonal to each other by the isomerized diazo dye molecule side chains. A polymer-dispersed liquid crystal element characterized in that dispersed liquid crystal layers are alternately laminated. 4. The polymer dispersed liquid crystal device according to claim 1, wherein the size of the liquid crystal region is smaller than the wavelength of visible light. 5. A polymerizable composition containing a polymerizable compound having a diazo dye molecule side chain and a low-molecular liquid crystal is irradiated with an interference wave to polymerize the polymerizable compound, and then irradiated with linearly polarized light. Then, the side chain of the diazo dye molecule is isomerized to thereby orient the low-molecular liquid crystal, thereby producing a liquid crystal device. 6. A polymerizable composition containing a polymerizable compound having a diazo dye molecule side chain and a low-molecular liquid crystal is heated or irradiated with light to polymerize the polymerizable compound.
By irradiating linearly polarized light, the diazo dye molecule side chains are isomerized, thereby orienting the low-molecular liquid crystal, and then further, interference light due to light whose deflection axis is orthogonal to the deflection axis of the linearly polarized light is further reduced. Irradiating a part of the diazo dye molecule side chain to isomerize, thereby making the orientation direction of one part of the low-molecular liquid crystal orthogonal to the orientation direction of the other part. .