JPH0125934Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to photochromic glasses whose light transmittance changes depending on the brightness of the outside world. Conventionally, photochromic glasses that use electro-optical elements to change the light transmittance depending on the brightness of the outside world have been used.
Some ideas have been devised, such as inserting a substance such as PLZT or liquid crystal whose optical rotation changes depending on voltage between two polarizing plates, or using an electrochromic substance that changes color through a redox reaction. . However, in the former case, two polarizing plates are required, so even in the most transparent state, the transmittance is only about 50%, and it is too dark to see clearly indoors, for example. This problem arose, making it impractical except for some special uses. In the latter case, unlike the former case, a polarizing plate is not required, so the lens has the advantage of being brighter, but it requires a relatively large current to flow in order to cause the redox reaction. However, due to its battery capacity, it was unsuitable for mobile use and was impractical. In order to eliminate this drawback, the inventor of the present invention
In No. 53-96714 (see Utility Model Application Publication No. 55-16526), we proposed photochromic glasses using liquid crystals to which a dichroic dye was added to give a guest-host effect.
The invention of Utility Model Application No. 53-96714, as shown in Figure 1, forms transparent electrodes 2 on the inner surfaces of two lenses 1 that serve as substrates, and overlaps them with a spacer 3 in between. A nematic liquid crystal 4 and a dichroic dye 5 are sealed in the formed void, and as in the case of using the electrochromic material, a polarizing plate is not required, so a sufficiently large maximum transmittance can be obtained, and Compared to electrochromic materials, they have the advantage of extremely low power consumption and excellent portability. However, in 1973-
In No. 96714, since there is only one layer of liquid crystal having a guest-host effect, a sufficient contrast ratio (ratio between maximum transmittance and minimum transmittance) cannot be obtained. That is, as shown in FIG. 1, the state in which the molecules of the elongated nematic liquid crystal 4 are parallel to the lens 1 is the state in which the dichroic dye 5 absorbs light and blocks it. Since it functions in the same way as a linear polarizer, some light wave components are blocked, but components perpendicular to this are allowed to pass through.As a result, the transmittance does not decrease much, the contrast ratio is low, and the anti-glare effect is sufficient. The disadvantage was that it was not possible to obtain A possible solution to this drawback is to use a two-layer liquid crystal layer. For example, Japanese Patent Application Laid-Open No. 53-55047 concerning display devices has two liquid crystal layers in which a dichroic dye is added to a nematic liquid crystal having positive dielectric anisotropy to give it a guest-host effect. It is stated that an extremely high contrast ratio can be obtained by configuring the first and second layers so that the molecular directions are perpendicular to each other when the molecular directions of the first layer and the second layer are parallel to the substrate. There is. However, when a liquid crystal element having such a configuration is used for photochromic glasses, the following problems occur. That is, in a nematic liquid crystal having positive dielectric anisotropy, when a voltage is applied, the direction of the molecules is parallel to the direction of voltage application, that is, perpendicular to the substrate, and the transmittance is maximum at that time. Photochromic glasses usually have maximum transmittance, but when the outside world is bright, it is necessary to minimize transmittance to reduce glare, so under normal conditions the liquid crystal layer must always apply voltage. It will have to be done. However, as is clear from the way they are used as glasses, it is desirable for photochromic glasses to be as light as possible, and as a result, the capacity of the power source that can be used is severely limited, so it is necessary to constantly apply a voltage as described above. In such a configuration, power consumption increases significantly, and the power supply that can be used for photochromic glasses cannot be used for a long time.Furthermore, the voltage application stops when the drive circuit breaks down. In this case, the field of vision suddenly becomes dark, which has the fatal disadvantage of potentially causing a serious accident, for example when driving a car at night. The present invention was devised to eliminate these conventional drawbacks, and consists of a liquid crystal layer in which a dichroic dye is added to a nematic liquid crystal having negative dielectric anisotropy to provide a guest-host effect. It is formed in two layers by at least three lens substrates each having a transparent electrode formed on the surface in contact with the layer, and when no voltage is applied to the surface of the lens substrate, the direction of the liquid crystal molecules is set relative to the lens substrate. It is characterized by performing an alignment process such that the first layer and the second layer are aligned in a perpendicular direction, parallel to the lens substrate when a voltage is applied, and perpendicular to each other in the first layer and the second layer. With this structure, in the state where light is absorbed, the directions of the molecules of the dichroic dye are perpendicular to each other according to the direction of the molecules of the nematic liquid crystal, so that the light incident on the first layer is dichroic. The light wave component in the direction parallel to the plane of the figure is absorbed by the chromatic dye 10 and becomes linearly polarized light. Next, the dichroic dye 1 of the second layer
2 absorbs the light wave component in the direction perpendicular to the plane of the drawing that has passed through the first layer, so the light transmittance is significantly reduced compared to the conventional one. In the state where light is allowed to pass through, all molecules pass through lens 6 and intermediate lens 1.
3, the maximum transmittance is slightly inferior to the conventional case where the liquid crystal layer is one layer, but the maximum transmittance is sufficiently bright for practical use. Note that even if the number of liquid crystal layers is increased to three or more, the maximum transmittance simply decreases and becomes darker, but the light absorption property, that is, the minimum transmittance hardly changes. Therefore, the maximum transmittance decreases, the contrast ratio also decreases, and the cost also increases, so a two-layer liquid crystal layer is optimal. In addition, as a method to change the light transmittance by applying voltage to the liquid crystal layer, (1) A solar cell is used both as a power source and a photocell that detects the brightness of the outside world, and a voltage is applied to the transparent electrode according to the brightness. How to supply. (2) A method that eliminates the need for battery replacement by combining solar cells and small batteries. etc. A detailed explanation will be given below based on examples. As shown in Figure 2, the radius of curvature is 70 with inorganic glass.
Two lens substrates 6 having a thickness of 1.5 mm and a thickness of 1.5 mm were made, and a transparent electrode 7 of indium oxide was formed on the inner surface in contact with the liquid crystal layer. Further, an intermediate lens base material 13 having a radius of curvature of 70 mm and a thickness of 0.5 mm was similarly made of inorganic glass, and transparent electrodes 7 were formed on both sides. Using the space 8 of the polyester film, two voids of about 10μ are formed, and each void has an ester-based nematic liquid crystal 9, 11 having negative dielectric anisotropy.
and purple dichroic dyes 10 and 12, trade name GR-No. 17 (manufactured by Nikko Kanko Shiki Co., Ltd.). In this case, by applying vertical alignment treatment and oblique vapor deposition alignment treatment to the surface of the transparent electrode 7, the molecules are aligned in a direction perpendicular to the lens base material 6 and the intermediate lens base material 13 when no voltage is applied. When light is transmitted and a voltage is applied, the molecules form the lens base material 6 and the intermediate lens base material 1.
They absorb light by arranging them in directions parallel to 3 and perpendicular to each other. The amount of dichroic dye added is
0.12wt% and 0.20wt%, and in this state, the average transmittance in the visible range was measured while turning on and off a voltage of 5V, and the results were as shown in the table below.

[Table] As is clear from the above, the present invention consists of two layers of liquid crystal having a guest-host effect, and the directions of the molecules of the nematic liquid crystal and dichroic dye in each layer are perpendicular to each other when a voltage is applied. Since the alignment treatment has been performed so that Using a nematic liquid crystal with a dielectric anisotropy of Therefore, even if voltage suddenly stops being applied due to malfunction or battery life, there is no risk of trouble that could lead to a serious accident, and voltage can only be applied when necessary. Since the battery capacity is extremely small or it can be driven only by solar cells, it has many practical effects, such as making it possible to realize extremely lightweight photochromic glasses. In addition, in the example, the lens base material 6 and the intermediate lens base material 13 were made of inorganic glass, but
Plastic material may be used to reduce weight. Further, prescription sunglasses by adding refractive power to the lenses are also included within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of conventional photochromic glasses. FIG. 2 is a diagram showing the configuration of the photochromic glasses of the present invention. 6... Lens base material, 7... Transparent electrode, 8... Spacer, 9, 11... Nematic liquid crystal, 10, 1
2...Dichroic dye, 13...Intermediate lens base material.

Claims (1)

[Scope of utility model registration request] In photochromic glasses that change the transmittance of light by applying a voltage to a liquid crystal layer made by adding a dichroic dye to a nematic liquid crystal to give it a guest-host effect, transparent electrodes are provided on each surface in contact with the liquid crystal layer. First and second voids are formed by stacking the formed at least three lens substrates via spacers, and each void is filled with a nematic liquid crystal having negative dielectric anisotropy and a dichroic dye. In addition, when no voltage is applied to each surface on which the transparent electrode is formed, the molecules of the liquid crystal are aligned in a direction perpendicular to the surface, and when a voltage is applied, the molecules of the liquid crystal are aligned parallel to the surface and in the first direction. The photochromic glasses are characterized in that they are subjected to an alignment treatment in which the gap and the second gap are aligned in directions perpendicular to each other.