JPH0497221A - Optical element - Google Patents

Abstract

PURPOSE:To reduce electric power consumption by nearly equaling the refractive indices of the high-polymer material and liquid crystal material of a composite material in the state of not impressing a voltage thereto and generating a difference in the refractive indices of the high-polymer material and the liquid crystal material in the state of impressing the voltage thereto. CONSTITUTION:The composite material 6 consists of the mixture composed of the high-polymer material 7 and the liquid crystal material 8 which is nearly equal in the refractive index in the state of not impressing the voltage between electrodes 3 and 4 facing each other to the refractive index of the high-polymer material. A photosensitive resin, such as, for example, UV curing resin, is used as the high-polymer material 7 in this case and the liquid crystal compsn. having the large refractive index anisotropy DELTAn and the refractive index of the bulk nearly equal to the refractive index of the high-polymer material 7 is used as the liquid crystal material 8. A liquid crystal compd. of, for example, a cyano biphenyl system, is used for this liquid crystal compsn. The optical element which allows the transmission of light when not impressed with the voltage and can scatter the light when impressed with the voltage is obtd. in this way.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to an optical element using a liquid crystal material.

[Background of the Invention] Conventionally, T N (twistedne) has been used as a display for word processors, personal computers, etc.
matic) type and S T N (super
2. Description of the Related Art Twisted nematic type liquid crystal display panels are widely known. This liquid crystal display panel uses polarizing plates to control light absorption and transmission.
In order to align the polarization direction of the light, the polarizing plate absorbs more than half of the incident light.As a result, the brightness of the transmitted light is at most less than half of the incident light, resulting in a dark display. .

To solve this problem, optical elements have recently been developed that can control the transmission and scattering of light without using polarizing plates. This type of optical element consists of a composite material made by mixing a polymer material and a liquid crystal material, and this composite material is placed between a pair of transparent electrode substrates to refract light depending on the alignment state of the liquid crystal material in the composite material. The transmission and scattering of light is controlled by utilizing the properties of different rates.

[Problems with the prior art] However, in the optical element described above, when no voltage is applied, the light incident on the composite material is scattered due to the difference in refractive index between the polymer material and the liquid crystal material, resulting in a cloudy state. When a voltage is applied, the liquid crystal material becomes oriented, and the refractive index of the polymer material and the liquid crystal material become almost equal, and as a result, light incident on the composite material is transmitted without being scattered, creating a transparent state. . For this reason, the above-mentioned optical element has a drawback in that if it is desired to transmit light, a voltage must be constantly applied and stroked.

[Object of the invention] This invention was made in view of the above-mentioned circumstances, and its purpose is to transmit light when no voltage is applied, and scatter light when a voltage is applied. It is an object of the present invention to provide an optical element that can be used in various ways and has a simple structure.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention provides an optical element in which a composite material in which a polymer material and a liquid crystal material are mixed is sealed between a pair of transparent electrode substrates on which opposing electrodes are formed. The key point of the composite material is that it is made of a mixture of a polymer material and a liquid crystal material whose refractive index in a state where no voltage is applied between opposing electrodes is approximately equal to the refractive index of the polymer material.

[Example] The present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 shows a first embodiment. In this figure, reference numeral 1.2 denotes transparent substrates made of glass or the like, which are arranged vertically facing each other. Transparent electrodes 3.4 made of ITO (a mixture of indium oxide and tin oxide) or the like are patterned on opposing surfaces of each transparent substrate 1, 2. A sealing material 5 is provided in a frame shape in the peripheral portion between each transparent substrate 1 and 2, and a composite material 6 is sealed between the transparent substrates 1 and 2 surrounded by this sealing material 5. The composite material 6 is a mixture of a polymer material 7 and a liquid crystal material 8, and the mixing state is determined by the ratio in which the amount of the liquid crystal material 8 is greater than that of the polymer material 7, for example, the ratio of the polymer material 7 to the liquid crystal material 8. are mixed at a ratio of about 1=9 to 4:6. Therefore, in the composite material 6, more than 50% of the liquid crystal material 8 is mixed in the polymer material 7, and the liquid crystal materials 8 are interconnected. In this case, as the polymer material 7, for example, a photosensitive resin such as an ultraviolet curable resin is used. Further, as the liquid crystal material 8, a liquid crystal composition having a large refractive index anisotropy Δn and a bulk refractive index substantially equal to the refractive index of the polymer material 7 is used, and this liquid crystal composition includes, for example, a cyanobiphenyl-based liquid crystal compounds are used.

When manufacturing such an optical element, first, a monomer or oligomer ultraviolet curable resin is prepared as the polymer material 7, and this ultraviolet curable resin and the liquid crystal material 8 are mixed to form the composite material 6. . When this composite material 6 is sealed between the pair of upper and lower transparent substrates 1 and 2, the transparent substrates 1.2 on which the transparent electrodes 3.4 are patterned are joined with a sealing material 5 at a predetermined interval. After injecting the composite material 6 into this gap and sealing the injection port, the polymer material 7 is polymerized by irradiation with ultraviolet rays. Alternatively, a transparent substrate l
, 2, for example, the composite material 6 is coated on the surface of the lower transparent substrate 1 facing the transparent electrode 3, and the composite material 6 is encapsulated by sandwiching the composite material 6 between the lower transparent substrate 2 and the sealing material 5, Thereafter, the ultraviolet curable resin is turned into a polymer by irradiation with ultraviolet rays. As a result, the so-called P N (polymer
network) type optical element is obtained. In addition, when providing a gap material (not shown) in order to keep the opposing distance between the transparent substrates 1 and 2 constant, the gap material may be sprayed after coating the composite material 6, or the gap material may be sprayed after coating the composite material 6. It may be mixed into the composite material 6 in advance.

As described above, the optical element described above has the following effects. When no voltage is applied to each transparent electrode 3.4 of the upper and lower transparent substrates 1 and 2, the refractive index of the polymer material 7 and the liquid crystal material 8 of the composite material 6 are almost equal, so that the light incident into the composite material 6 is passes through without scattering. When a voltage is applied to the transparent electrodes 3.4 of the transparent substrates 1 and 2 facing each other, the liquid crystal material 8 is oriented according to the electric field, and the difference in refractive index between the polymer material 7 and the liquid crystal material 8 is created. As a result, the light incident on the composite material 6 is scattered at the interface between the polymer material 7 and the liquid crystal material 8, and the display of the optical element becomes cloudy. Therefore, according to such an optical element, when it is desired to transmit light, there is no need to constantly apply a voltage, so power consumption can be reduced, and a polarizing plate is not required, so the transmittance is high. Not only does it have good transparency, but it also has an extremely simple structure because it does not require an alignment film or rubbing treatment unlike conventional TN or STN liquid crystal display panels.

In the above embodiments, a photosensitive resin such as an ultraviolet curable resin was used as the polymer material 7, but the invention is not limited to this. For example, a two-part curable epoxy resin consisting of a main resin and a curing agent may also be used. good. In this case, since the curing agent hardens over time, it is sufficient to coat the composite material before it hardens and seal it between the upper and lower transparent substrates 1 and 2. By mixing the curing agent of the curable epoxy resin and the liquid crystal material 8 and then mixing these with the main resin, more than 50% of the liquid crystal material 8 is mixed in a two-part curable epoxy resin in a connected state. I can do it.

FIG. 2 shows a second embodiment. This optical element differs from that of the first embodiment described above only in the composite material 10, and the other parts have the same structure.

This composite material 10 is the same material as the first embodiment described above, but its mixing ratio is different. That is, the polymer material 11
The mixing ratio of the liquid crystal material 12 and the liquid crystal material 12 is the same ratio, or the amount of the liquid crystal material 12 is reduced. Therefore, this composite material has a so-called F D (
It is of the polymer dispersed type. In this composite material 10 as well, the bulk refractive index of the liquid crystal material 12 is approximately equal to the refractive index of the polymer material 11;
A liquid crystal composition having a large refractive index anisotropy Δn is used. It goes without saying that such an optical element also has the same effects as those of the embodiments described above.

The optical element of the present invention can be used not only as a blind that blocks light, a light shutter, etc., but also as a display that displays information electro-optically.

[Effects of the Invention] As explained in detail above, according to the present invention, the refractive index of the polymer material of the composite material and the liquid crystal material are almost equal when no voltage is applied, and the refractive index of the polymer material and the liquid crystal material are almost equal when no voltage is applied. Since the structure is configured such that there is a difference in the refractive index of the liquid crystal material, light can be transmitted when no voltage is applied, and light can be scattered when a voltage is applied. For this reason,
When you want to transmit light, there is no need to constantly apply a voltage, which reduces power consumption.Furthermore, it does not require a polarizing plate, so it has good transmittance, has a simple structure, and is inexpensive to install. can be made.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of an optical element according to a first embodiment of the invention, and FIG. 2 is an enlarged sectional view of an optical element according to a second embodiment. l, 2...Transparent substrate, 3.4...Transparent electrode, 6.10...Composite material, 7.11...
...Polymer material, 8,12...Liquid crystal material.

Claims (1)

[Scope of Claims] An optical element in which a composite material in which a polymer material and a liquid crystal material are mixed is sealed between a pair of transparent electrode substrates on which opposing electrodes are formed, wherein the composite material faces the polymer material. An optical element comprising a mixture with a liquid crystal material whose refractive index in a state where no voltage is applied between electrodes is approximately equal to the refractive index of the polymer material.