JP3296096B2 - Liquid crystal light control body and light control window using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal light adjuster made of a liquid crystal material and a light adjusting window using the same, and more particularly, to a liquid crystal light adjuster excellent in light transmittance control performance and using the same. Light control window.

[0002]

2. Description of the Related Art In buildings, automobiles and the like, the inflow of solar energy from windows greatly affects the air-conditioning load in a room. Is coming.

[0003] It is considered that it is necessary to be able to select optical characteristic values of at least a transparent glass currently used as a window glass and a heat ray absorbing glass intended to absorb sunlight energy as a dimming range which is practically desired. , The dimming range is the range of change in transmittance of sunlight energy (hereinafter “ΔT
g ") is 15% or more. Here, the sunlight transmittance Tg is obtained by multiplying the total transmitted light by the intensity distribution coefficient of sunlight energy (JIS).
R 3106).

Conventionally, an electrochromic device (hereinafter, referred to as an “EC device”) has been known as one of the devices having such a light controlling function (hereinafter, referred to as a “light controlling device”). The EC element uses a material with a spectrum change due to an electrochemical oxidation-reduction reaction, such as tungsten oxide or Prussian blue, and the amount of transmitted sunlight energy can be controlled by light absorption.

[0005] However, since the EC element is of a current-driven type, when the area is increased, the response speed is remarkably reduced due to a large voltage drop, and deterioration due to electrochemical changes of constituent materials caused during long-time energization is avoided. Therefore, a large-area element having sufficient practical durability has not been realized.

[0006] Therefore, as a substitute for such a current-driven EC device, a voltage-driven dimming device has attracted attention. Japanese Patent Application Laid-Open No. 58-50163 discloses a liquid crystal element having excellent durability and a dimming function capable of easily increasing the area.
No. 1 has a nematic (NC
2. Description of the Related Art Liquid crystal devices having a nematic curvilinear aligned phase (AP) and liquid crystal devices obtained by a phase separation method described in JP-A-60-502128 are known. These elements operate based on the following principle.

In the liquid crystal device described in this publication, in which small droplets of a liquid crystal substance are dispersed in an inexpensive polymer, when no voltage is applied, the liquid crystal is arranged along the curved surface of the polymer wall, so that the optical path is twisted. At the interface between the polymer and the liquid crystal droplets, light is reflected and scattered, and looks milky white.

On the other hand, when a voltage is applied, the liquid crystals in the liquid crystal droplets are arranged in the direction of the electric field by an external electric field, and at this time, the ordinary light refractive index no of the liquid crystal and the refractive index np of the polymer are selected so as to match. Accordingly, the light that is perpendicularly incident on the liquid crystal element surface passes without being reflected at the interface between the liquid crystal and the polymer, so that the liquid crystal element is transparent.

Although the liquid crystal element (hereinafter sometimes referred to as a “polymer-dispersed liquid crystal element”) can adjust the transparency, most of the light incident on the liquid crystal element when no voltage is applied is equal to the incident side. Since the light was scattered on the opposite side (hereinafter referred to as “forward”), the amount of transmitted solar energy hardly decreased compared to when voltage was applied, and only a few% ΔTg was obtained.

In order to solve the above problems, a method of adding a polychromatic dye to a liquid crystal material used in a polymer dispersed type liquid crystal element to increase light absorption when no voltage is applied is disclosed in Japanese Patent Application Laid-Open No. HEI 3 (1993) -207. -66162. Although this element has a large ΔTg, it can be used for outdoor applications such as architecture and automobiles that are exposed to sunlight for a long period of time because the polychromatic dye is inherently deteriorated by light and heat. Did not.

The inventor of the present invention has variously changed the parameters of the polymer-dispersed liquid crystal device and has examined the relationship with ΔTg in detail. By suitably combining the various parameters, more incident light scattered forward is incident. Side (hereinafter referred to as “rearward”), the amount of transmitted light when no voltage is applied is reduced, the light transmittance control performance is significantly increased, and ΔTg is 15
% Can be obtained (Japanese Patent Application No. 3-270934).

[0012]

However, there is a need in the market for dimmers having a larger ΔTg.
For example, when producing a dimmer in which a polymer-dispersed liquid crystal element is sandwiched between a pair of transparent bodies via a plastic adhesive film, if a colored glass having a low transmittance is used as the transparent bodies, no voltage is applied. Sometimes the transmittance is lower than that of the liquid crystal element alone due to the absorption of light by the colored glass, and a larger ΔTg may be obtained. The technology for manufacturing the dimmer has already been established, and the area can be easily increased (Japanese Utility Model Application Laid-Open No. 64-32124). However, in the above configuration, even when a voltage is applied, the transmittance is reduced similarly to when no voltage is applied, so that ΔTg hardly changes.
No larger ΔTg has been obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and a liquid crystal light adjuster which is easy to increase in area and has more excellent light control performance, and light control using the same. The purpose is to provide windows.

[0014]

That is, according to the present invention, a transparent conductive film is provided on each of opposing surfaces of a pair of transparent substrates,
In a liquid crystal element in which a medium holding a liquid crystal substance in a gap is interposed between the transparent conductive films, an absorbing anisotropic transparent body is laminated on an outer surface of one substrate of the liquid crystal element. Liquid crystal light adjuster.

Further, according to the present invention, a transparent conductive film is provided on the opposing surfaces of a pair of transparent substrates, and a medium holding a liquid crystal substance in a gap is interposed between the transparent conductive films to form a liquid crystal element. A liquid crystal light modulator is formed by laminating an absorbing anisotropic transparent body on the outer surface of one substrate of the liquid crystal element, and the surface on which the absorbing anisotropic transparent body is formed is the indoor side, and the non-formed surface is the outdoor side. A dimming window, wherein the liquid crystal dimmer is attached to an opening.

FIG. 2 is an apparatus for explaining the measurement principle of the method for evaluating the optical characteristics of a transparent substrate, and only the main parts are illustrated. The measuring device is composed of a light source (8) and a detector (9), and a transparent substrate as a sample (10) is located between the light source (8) and the detector (9), and on a line connecting the two. The center position in the longitudinal direction is held from both side surfaces by an auxiliary tool (not shown), and is rotatable by a shaft.

In FIG. 2, a white light source containing each light component and capable of obtaining a parallel beam is used as the light source (8). However, the present invention is not limited to this. It also includes fluorescent lights. The detector (9) is an optical-electrical converter, which receives the detection light emitted from the light source (8) and converts an input optical signal into an electric signal.

In FIG. 2, the light source (8) is used to
0) The surface is irradiated with detection light, and an angle between the incident detection light and the normal (11) of the sample (10) is defined as an incident angle θ.
The sample (10) is rotated by a certain angle about the axis, and the transmittance T and the transmitted light intensity at each angle are detected by the detector (8).

FIG. 3 is a graph showing a change in the transmittance T with respect to the incident angle θ. For example, a colored transparent glass substrate or transparent plastic substrate does not have anisotropy in the absorption coefficient, so that the absorption coefficient does not change with respect to the angle θ. Therefore, the transmittance T (θ) is, as shown by the broken line in FIG.
The optical path length (the distance of light passing through the substrate, which is equal to the thickness d of the substrate when θ = 0) becomes lower than T (θ = 0) by the length of d · (1−cos θ) / cos θ.

On the other hand, when the absorption anisotropic transparent body (7) is used as the sample (1), the absorption coefficient changes with respect to the angle θ, and the absorption coefficient increases as the angle θ increases. . As a result, as shown by the solid line in FIG. 3, the T (θ) of the absorption anisotropic transparent body (7) becomes larger as the angle θ becomes larger than that of the colored transparent substrate or the transparent plastic substrate. The transmittance T sharply decreases.

FIG. 4 is a graph showing the angle dependence of the transmitted light of the liquid crystal light adjuster. The figure shows the measurement of the angle dependence of the transmitted light intensity (relative value) when light is incident perpendicularly to the substrate surface of the liquid crystal light controller. When no voltage is applied to the body (hereinafter “of
f), and the broken line indicates a state in which a voltage is applied so that the liquid crystal light adjuster is sufficiently transparent (hereinafter referred to as “on”). At the time of off, light incident on the liquid crystal light adjuster is emitted over a wide angle. On the other hand, when it is on, most of the light that has entered the liquid crystal light adjuster goes straight and exits.

By laminating an absorbing anisotropic transparent body on one liquid crystal element surface and arranging the other liquid crystal element surface on the light source side, light emitted from the liquid crystal element at a wide angle at the time of off is greatly attenuated. Therefore, the total transmitted light decreases, and as a result, Tg decreases.

On the other hand, when the light is on, the straight traveling light is only slightly attenuated by the transparent transparent anisotropic substrate, and Tg hardly decreases. Therefore, ΔTg increases.

When the transparent transparent anisotropic material laminated on the surface of the liquid crystal element is disposed on the light source side, the light emitted from the light source is slightly attenuated by the transparent transparent anisotropic material and enters the liquid crystal element. Therefore, ΔTg hardly changes, as in the case where a transparent substrate having no anisotropy in the absorption coefficient is laminated.

There is no particular limitation on the absorption anisotropic transparent material as long as it has an anisotropic absorption coefficient and is plate-shaped over a large area. For example, FIGS.
As shown in (1), a light control film (12) (hereinafter referred to as "LCF") having a louver-shaped relief (14) formed on a transparent plastic film (13) can be applied. FIG. 5 shows a stripe type LCF, and FIG. 6 shows a honeycomb type LCF.

The stripe-type LCF has a dependence on the in-plane orientation as shown in FIG.
At 0 degrees, that is, in the direction perpendicular to the length direction of the relief (14), the transmittance T greatly changes with respect to the viewing angle θ, but in the direction parallel to the length direction of the relief (14). (The in-plane angle α is 0 degree), the transmittance T hardly depends on the viewing angle θ.

On the other hand, in the honeycomb type LCF, the transmittance T greatly depends on the viewing angle θ as shown in FIG.
And since it hardly changes in all directions,
A larger ΔTg can be obtained as compared with a case where a stripe-type LCF is laminated on a polymer-dispersed liquid crystal element. Furthermore, if the dependency of the transmittance T of the LCF on the viewing angle θ is greater, that is, the transmittance T at the viewing angle θ = 0 ° is higher and the transmittance T is lower as the viewing angle θ is larger, the LCF Of a liquid crystal element in which
Tg increases.

Further, the liquid crystal light adjuster of the present invention is attached to an opening of a building or the like to form a light adjusting window. In this case, as described above, the surface on which the absorption anisotropic transparent body of the liquid crystal light modulator is laminated is attached to the opening on the indoor side, that is, as a non-light source, so that Tg is reduced at the time of off, and Tg hardly decreases at the time of on. Therefore, ΔTg can be increased as a result.

[0029]

In the liquid crystal light modulator of the present invention, since the absorption anisotropic transparent material is laminated on the outer surface of one of the transparent substrates of the liquid crystal element, a large change in transmittance of sunlight energy can be obtained. .

Such a characteristic focuses on the state change of the forward scattered light when the voltage is not applied to the liquid crystal light adjuster and when the voltage is not applied to the liquid crystal light adjuster. This is made possible by shutting off and hardly attenuating the straight transmitted light in the applied state.

In the liquid crystal light adjuster of the present invention, the light control performance is improved without changing the structure of the polymer dispersed liquid crystal element, so that the transparency can be sufficiently adjusted as in the prior art, and the deterioration hardly occurs. And excellent durability.

In the light control window of the present invention, an anisotropic transparent body is laminated on the outer surface of one of the transparent substrates of the liquid crystal light control body. Since the liquid crystal light adjuster is attached to the opening with the non-formed surface facing the outside, the sunlight energy flowing from outside can be sufficiently controlled.

[0033]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

FIG. 1 is a schematic sectional view of a liquid crystal light adjuster of the present invention. In FIG. 1, (1) is a liquid crystal element, (2) is a transparent substrate, (3) is a transparent conductive film, and (4) is a transparent conductive film. The medium and (5) indicate the liquid crystal material.

For example, the liquid crystal element of the liquid crystal light modulator of the present invention is manufactured by the following method. First, an emulsion is prepared by mixing a liquid crystal substance and an aqueous phase, and the emulsion is added to latex, or the liquid crystal substance and latex are directly mixed to prepare an emulsion.
When forming an emulsion, it is preferable to add a surfactant in order to form stable liquid crystal particles. Mixing is performed by various mixers such as a blender and a colloid mill. Next, a crosslinking agent is added to crosslink the latex to form a medium (4), and then the medium (4) is converted to a transparent substrate formed with a transparent conductive film (3) by a knife blade or other suitable means. (2) Apply on top and dry. Then, it is bonded to another transparent substrate (2) with a transparent conductive film (3) to obtain a liquid crystal element.

Thereafter, one substrate (2) of the liquid crystal element
The liquid crystal light modulator (1) of the present invention shown in FIG. In this case, the absorption anisotropic transparent body (7) is usually laminated on the substrate (2) via an adhesive (not shown).

The dimming window of the present invention is provided by mounting the transparent anisotropic transparent body (7) of the liquid crystal dimmer (1) shown in FIG. Get.

(Example 1) Nematic liquid crystal ZLI-32
19 (Merck Japan) surfactant IGEPAL
CO-610 (manufactured by GAF) was added in an amount of 0.5 wt%, and latex particles 4 were added so that the liquid crystal ratio became 0.62.
It was added to Neorez R-967 (manufactured by Polyvinyl Chemical) containing 0% by weight, and 1500 was added using a homogenizer.
The mixture was stirred at 0 rotation for 10 minutes to obtain an emulsion. Next, a crosslinking agent CX-100 (manufactured by polyvinyl chemical) was added at a ratio of 3% by weight to R-967 while being slowly mixed. This mixture was applied on a polyethylene terephthalate (PET) film previously coated with an indium tin oxide (ITO) film using a doctor blade, and dried. The thickness after drying was about 18 μm. After the mixture was dried, it was bonded to another PET film with an ITO film to obtain a liquid crystal device. Then, using this liquid crystal element, an aqueous ethanol solution (25%) was sprayed on one of the PET films in a mist state, and the PET film and the stripe type LC were dispersed.
F (Asahi Kasei Kogyo Co., Ltd.) was bonded to an absorption anisotropic transparent body to obtain a liquid crystal light modulating body in this example.

(Embodiment 2) In Embodiment 1, a stripe-type LCF (manufactured by Asahi Kasei Kogyo Co., Ltd.) was used as the absorption anisotropic transparent body of the liquid crystal light modulator, but in this embodiment, a honeycomb type is used instead. Example 1 using LCF (manufactured by Asahi Kasei Corporation)
As in the case of the above, an aqueous ethanol solution (25%) was sprayed on one of the PET films in the form of a mist, and the PET film and a honeycomb type LCF (manufactured by Asahi Kasei Kogyo Co., Ltd.) were adhered to each other. I got a body.

Example 3 Using the liquid crystal light modulator obtained in Example 2, a striped LCF (manufactured by Asahi Kasei Kogyo Co., Ltd.) was fitted between columns of a building so as to be on the indoor side, and fixed with a sealing material. did.

(Comparative Example 1) The liquid crystal element of Example 1 before the stripe-type LCF (manufactured by Asahi Kasei Kogyo Co., Ltd.) was bonded to one PET film was used as the liquid crystal element of Comparative Example 1.

(Examples 1 and 2 and Comparative Example 1)
JIS R 31
No voltage applied according to 06 (off state)
And a sunlight transmittance Tg in a state where a voltage is applied between the opposite ITO films of the liquid crystal element (on state), and
Further, ΔTg was obtained from the measured values by calculation. Table 1 shows the results. Note that ΔTg is the change in transmittance of sunlight energy as described above, and more specifically, o
It represents the difference between the sunlight transmittance in the n state and the sunlight transmittance in the off state.

[0043]

[Table 1]

In the measurement, the transparent transparent anisotropic material was placed on the side opposite to the light source, that is, on the detector side. In the liquid crystal light adjuster obtained in Example 1, for the purpose of comparison, the measurement was also performed on a case where the absorption anisotropic transparent material was disposed on the light source side. The results are similarly shown in Table 1 using this as Comparative Example 2.

As is clear from Table 1, in the liquid crystal light modulators obtained in Examples 1 and 2, the absorption anisotropic transparent material laminated on the outer surface of the substrate was arranged on the side opposite to the light source. Thus, a larger transmittance change ΔTg of sunlight energy was obtained, and it can be seen that ΔTg was improved as compared with the conventional liquid crystal element alone.

[0046]

As described in detail above, the liquid crystal light adjuster of the present invention has a structure in which an absorption anisotropic transparent material is laminated on one substrate, and the other substrate is irradiated with the liquid crystal light adjuster. Since it is arranged on the light source side, as is clear from the example,
It is excellent in light transmittance control performance as compared with a polymer dispersed liquid crystal element obtained by a conventional method.

The dimming window of the present invention is a liquid crystal dimmer in which the surface on which the absorption anisotropic transparent body is formed is the indoor side and the non-formed surface is the outdoor side, and the liquid crystal dimmer is attached to the opening. Therefore, it is possible to sufficiently control the solar energy flowing from the outside.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a liquid crystal light adjuster of the present invention.

FIG. 2 is an explanatory diagram showing a measurement principle of the optical characteristic evaluation device.

FIG. 3 is a graph showing the relationship between the transmittance and the viewing angle of a transparent substrate and an absorption anisotropic transparent substrate.

FIG. 4 is a graph showing the relationship between the transmitted light intensity and the viewing angle of the liquid crystal light adjuster of the present invention.

FIG. 5 is a perspective structural view schematically showing a stripe-type absorption anisotropic transparent body used in the present invention.

FIG. 6 is a perspective structural view schematically showing a honeycomb-type absorption anisotropic transparent body used in the present invention.

FIG. 7 is a graph showing the relationship between the transmittance and the viewing angle when a stripe-type absorption anisotropic transparent body is used.

FIG. 8 is a graph showing the relationship between the transmittance and the viewing angle when a honeycomb-type absorption anisotropic transparent body is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal light modulator 2 Transparent substrate 3 Transparent conductive film 4 Medium 5 Liquid crystal material 7 Absorption anisotropic transparent material 8 Light source

Claims (4)

(57) [Claims] 1. A liquid crystal element comprising a transparent conductive film disposed on opposing surfaces of a pair of transparent substrates, and a medium holding a liquid crystal substance therein interposed between the transparent conductive films. A liquid crystal light adjuster, wherein an absorption anisotropic transparent material is laminated on the outer surface of one of the substrates. 2. The liquid crystal light control device according to claim 1, wherein the absorption anisotropic transparent material is a transparent material having a louver-shaped relief. 3. A liquid crystal element comprising a transparent conductive film disposed on opposing surfaces of a pair of transparent substrates, and a medium holding a liquid crystal substance interposed between the transparent conductive films to form a liquid crystal element. A liquid crystal light adjuster is formed by laminating an absorption anisotropic transparent body on the outer surface of one of the substrates. A light control window, characterized in that a light control body is attached to the opening. 4. The light control window according to claim 3, wherein the absorption anisotropic transparent body is a transparent body having a louver-shaped relief formed thereon.