JP2940100B2 - Optical element - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical element using a liquid crystal material.

BACKGROUND OF THE INVENTION Conventionally, TN (twisted nematic) and STN have been used as displays for word processors and personal computers.
(Super twisted nematic) type liquid crystal display panels are widely known. Since this liquid crystal display panel uses a polarizing plate to control the absorption and transmission of light, the polarizing plate absorbs more than half of incident light because the polarizing plate has a polarization direction of light. For this reason, there is a problem that the brightness of the transmitted light is at most half of the incident light or less, and the display becomes dark.

In order to solve this problem, recently, an optical element capable of controlling transmission and scattering of light without using a polarizing plate has been developed. In this type of optical element, a polymer material and a liquid crystal material are mixed to form a composite material, and the composite material is sealed between a pair of transparent electrode substrates. The transmission and scattering of light are controlled by utilizing the properties having different refractive indices.

[Problems of the Prior Art] However, in the above-described optical element, when no voltage is applied to the opposing electrode substrate, light incident on the composite material due to a difference in refractive index between the polymer material and the liquid crystal material. When a voltage is applied, the liquid crystal material is oriented, and the refractive index of the polymer material and the liquid crystal material becomes almost equal, whereby light incident on the composite material is transmitted without being scattered. It becomes transparent. For this reason, the above-described optical element has a drawback that a voltage must be constantly applied to transmit light.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to transmit light when no voltage is applied and to scatter light when a voltage is applied. It is an object of the present invention to provide an optical element which can be manufactured and has a simple structure.

SUMMARY OF THE INVENTION In order to achieve the above-described object, the present invention provides an optical element in which a composite material obtained by mixing a polymer material and a liquid crystal material is sealed between a pair of transparent electrode substrates on which opposed electrodes are formed. The composite material is a mixture of a polymer material and a liquid crystal material having a refractive index substantially equal to the refractive index of the polymer material in a state where no voltage is applied between the opposed electrodes, and An ionic substance causing a disturbing motion to the liquid crystal molecules by the voltage applied between the opposing electrodes is added, and the disturbing motion generated by the ionic liquid of the ionic substance when the voltage is applied changes the orientation state of the liquid crystal material to scatter incident light. The main point is to make it happen.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a first embodiment. In this figure, 1, 2
Is a transparent substrate made of glass or the like, and is disposed to face up and down. Transparent electrodes 3 and 4 such as ITO (a mixture of indium oxide and tin oxide) are pattern-formed on opposing surfaces of the transparent substrates 1 and 2. A sealing material 5 is provided in a frame shape around the transparent substrates 1 and 2, and a composite material 6 is sealed between the transparent substrates 1 and 2 surrounded by the sealing material 5. The composite material 6 is a mixture of a polymer material 7 and a liquid crystal material 8 to which an appropriate amount of an ionic substance 9 is added. In this case, as the polymer material 7, for example, a photosensitive resin such as an ultraviolet curable resin is used. 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. For example, a cyanobiphenyl-based liquid crystal composition is used as the composition. Liquid crystal compounds are used. In the liquid crystal material 8 dispersed in the polymer material 7, it is desirable that the liquid crystal molecules are oriented in a predetermined direction by applying a stress to the polymer material 7. Further, the ionic substance 9 causes a disturbance movement of the liquid crystal molecules when a voltage is applied to the transparent electrodes 3 and 4, such as tetrabutyl, ammonium bromide, tetraethylammonium perchlorate, Chafulvalene or the like is used. The mixing state may be such that the mixing ratio between the polymer material 7 and the liquid crystal material 8 is about 1: 9 to 9: 1. In the case of the polymer network type, the mixing ratio of the polymer material 7 and the liquid crystal material 8 is about 1: 9 to 4: 6,
50% or more of the liquid crystal material 8 is mixed in the polymer material 7. The ionic substance 9 may be added in a small amount of about 0.1 to 10% by weight based on the mixture of the polymer material 7 and the liquid crystal material 8.

When manufacturing such an optical element, first, a monomer or oligomer UV-curable resin is prepared as the polymer material 7, and the UV-curable resin is mixed with a liquid crystal material 8 to which a small amount of ionic substance 9 is added. Thus, the composite material 6 is formed. When the composite material 6 is sealed between a pair of upper and lower transparent substrates 1 and 2, the transparent substrates 1 and 2 on which the transparent electrodes 3 and 4 are formed are joined with a sealing material 5 at predetermined intervals. Then, the composite material 6 is injected into the gap, the injection port is sealed, and then the polymer material is polymerized by irradiating ultraviolet rays. Alternatively, a composite material 6 is coated on one of the transparent substrates 1 and 2, for example, a surface of the lower transparent substrate 1 on the side of the transparent electrode 3, and is sandwiched between the lower transparent substrate 2 and the sealing material 5. 6 is then enclosed, and then ultraviolet rays are irradiated to polymerize the ultraviolet curable resin. Thereby, the liquid crystal material 8 was connected to the polymer material 7.
A PN type optical element is obtained. When a gap material (not shown) is provided in order to keep the distance between the transparent substrates 1 and 2 constant, the gap material may be sprayed after the composite material 6 is coated. It may be mixed in the composite material 6 in advance.

As described above, according to the above-described optical element, the following operation and effect can be obtained. When no voltage is applied to the transparent electrodes 3 and 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 substantially equal, and the ionic substance 9 causes disturbance movement. Since there is no light, the light incident on the composite material 6 is transmitted without being scattered. In this case, if the liquid crystal molecules are oriented in a predetermined direction, the transmittance is even higher. When a voltage is applied to the transparent electrodes 3 and 4 of the transparent substrates 1 and 2 facing each other, a turbulence is generated in the liquid crystal molecules by the ionic substance 9, and the turbulence and the birefringence of the liquid crystal cause Incident light is scattered in the liquid crystal layer, and the display of the optical element becomes cloudy. Therefore, according to such an optical element, when it is desired to transmit light, it is not necessary to constantly apply a voltage, so that the consumption electrodes can be reduced, and since a polarizing plate is not required, the transmittance is high. In addition to having good transparency, the structure is extremely simple because an alignment film and a rubbing treatment are not required unlike the conventional TN type or STN type liquid crystal display panel.

In the above-described embodiment, a photosensitive resin such as an ultraviolet curable resin is used as the polymer material 7, but is not limited thereto.
For example, a two-component curable epoxy resin composed of a main agent and a curing agent may be used. In this case, the curing agent cures with the lapse of time. Therefore, before the curing, the composite material may be sealed between the upper and lower transparent substrates 1 and 2 by injection or coating. In this composite material, a liquid crystal material 8 to which a curing agent of a two-component curable epoxy resin and an ionic substance 9 are added is used.
And then mixing them with the main ingredient to obtain 2
More than 50% of the liquid crystal material 8 can be mixed in the liquid curing type epoxy resin in a connected state.

FIG. 2 shows a second embodiment. This optical element has the same structure as that of the first embodiment described above except for the composite material 10. That is, the composite material 10 is a so-called PD (polymer disperse) in which the liquid crystal material 8 is mixed in the polymer material 7 in a discontinuous state without being connected.
d) type, in which a polymer material 7 and a liquid crystal material 8 to which an ionic substance 9 is added are mixed. In this case, each substance of the composite material 10 is the same as in the first embodiment, but the mixing ratio is different from that of the first embodiment. That is, the mixing ratio between the polymer material 7 and the liquid crystal material 8 is about 5: 5 to 9: 1, and the ionic substance 9 may be added in a small amount as in the first embodiment.
Thereby, the liquid crystal material 8 in the polymer material 7 is reduced to 50% or less, and a PD-type composite material 10 in which the liquid crystal materials 8 are not connected to each other is obtained. Also in this composite material 10,
As the liquid crystal material 12, a liquid crystal composition having a bulk refractive index substantially equal to that of the polymer material 11 and a large refractive index anisotropy Δn is used. In this case, it is desirable that the liquid crystal molecules in the composite material 10 be oriented in a predetermined direction. It goes without saying that such an optical element has the same operation and effect as those of the above-described embodiment.

Incidentally, the optical element of the present invention is a blind that blocks light,
In addition to being used as an optical shutter or the like, it can also be used as a display or the like for displaying information electro-optically.

[Effects of the Invention] As described in detail above, according to the present invention, a polymer material and a liquid crystal material having substantially the same refractive index are applied to a mixture in which no voltage is applied by a voltage applied between opposing electrodes. Since the liquid crystal molecules form a composite material by adding an ionic substance causing a disturbing motion, when a voltage is applied to the composite material, a disturbing motion is generated by an ionic current of the ionic substance, and the disturbing motion changes the orientation state of the liquid crystal material. The incident light can be scattered by being changed, and when no voltage is applied, no disturbance movement occurs due to the ion current and the light can be transmitted. Therefore, when light is desired to be transmitted, it is not necessary to constantly apply a voltage, the consumption electrodes can be reduced, and the polarizing plate is not required, so that the transmittance is good, the structure is simple, and the manufacturing is inexpensive. can do.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of an optical element according to a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view of an optical element according to a second embodiment. 1, 2,... Transparent substrate, 3, 4,... Transparent electrode, 6, 10,.
Composite material, 7 Polymer material, 8 Liquid crystal material, 9
Ionic substances.

Claims (1)

(57) [Claims] 1. 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. And a liquid crystal material having a refractive index substantially equal to the refractive index of the polymer material in a state where no voltage is applied between the electrodes, and a liquid crystal molecule is applied to the mixture by the voltage applied between the opposing electrodes. An optical element, characterized in that an ionic substance causing a disturbing motion is added to the optical element.