JPH04195020A - Magnetooptical element - Google Patents

Abstract

PURPOSE:To optionally switch a transparent state and an opaque state by using a magnetooptical effect provided with bismuth substitution yttrium iron garnet(BiYIG). CONSTITUTION:A DC current is applied to a solenoid 3 by a power source 4 so as to impress a magnetic field on the substrate of three-layer structure consisting of a BiYIG layer 1 and transparent substrates 2a and 2b. When light is made incident on the substrate vertically, the light is scattered and becomes the opaque state. Even when the power source 4 is turned off, the state is held. Next, when the attenuation AC current of about 50Hz is applied to the solenoid 3 by the power source 4 to gradually lower voltage, the light is not scattered and becomes the transparent state. Even when the power source 4 is turned off, the state is held and memory property is presented. Thus, the transparent state and the opaque state are switched.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention can be used to block sunlight by arbitrarily switching between a light-transmitting state and a non-transmitting state, such as a window of a building structure or a light shutter. , relates to a magneto-optical element that can be used for information processing.

(Prior Art) Conventionally, liquid crystal display devices (hereinafter simply referred to as LCD) and electrochromic display devices (hereinafter simply referred to as ECD) have been used for light-shielding glass and light shutters.
is proposed. Both LCDs and ECDs have become very expensive because they use transparent substrates with expensive transparent electrodes.

In particular, LCDs are transparent when a voltage is applied, become cloudy when no voltage is applied, and generally lack memory (the property of retaining displayed content even when the power is turned off), making them extremely difficult to use.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks of conventionally known light-shielding glasses, that is, eliminates the need to use an expensive transparent substrate with transparent electrodes and to maintain a transparent state without continuously applying a voltage. This was done for the purpose of improving the ability to maintain an opaque state.

(Means for Solving the Problems) That is, the present invention is characterized in that a layer containing fine powder of bismuth-substituted yttrium iron garnet in a transparent resin binder is interposed between two transparent glass substrates. This is a magneto-optical element.

In the present invention, bismuth-substituted yttrium iron garnet (Bix
Fine particles of Y3-X Fes 012 (hereinafter referred to as BiYJG) are kneaded with a transparent resin binder to form an ink, which is then applied and formed. The content of BiYIG is 10% by weight or more and 80% by weight or less. As the transparent resin binder, any transparent resin such as acrylic resin, urethane resin, polyolefin, etc. may be used. A solenoid for generating a magnetic field is built into the top and bottom or left and right sides of the frame.

BiYIG used in the magneto-optical element of the present invention is synthesized by using a coprecipitation method to produce BiYIG fine particles.

(Function) The magneto-optical element of the present invention is capable of arbitrarily switching between a transparent state and an opaque state by using the magneto-optic effect of BiYIC. More specifically, the magneto-optical effect used in the present invention is called the Cotton-Mouton effect or magnetic birefringence effect, which occurs when a magnetic field is applied perpendicular to the direction of incidence of light to align the direction of magnetization. It is an effect. At this time, BiY
Since IG is used in the form of fine particles dispersed in a resin binder, the birefringence effect differs depending on the location. This means scattering of light, so if the direction of magnetization is aligned perpendicular to the direction of light incidence, an opaque state can be created. To achieve a transparent state, the directions of magnetization may be varied by, for example, alternating current demagnetization. Also BiYIG
Since it is a magnetic material, as long as the directions of -degree magnetization are aligned, the magnetic force is maintained even without applying a magnetic field. Although there are various methods for producing fine particles, such as a CVD method and a pulverization method, it is preferable to use a coprecipitation method. The coprecipitation method is a method in which an alkali is added to nitrate to precipitate heavy metal elements, which have a smaller ionization tendency than the alkali, as hydroxides, and then calcined to obtain the desired BiYIG. The coprecipitation method is a particularly excellent manufacturing method for the purpose of the present invention because the particle size can be changed depending on the manufacturing conditions, and it can be produced inexpensively and in large quantities.

(Example) To explain the magneto-optical element of the present invention based on the drawings, FIG. 1 is a perspective view showing the structure of a curtain glass.

Bismuth nitrate (Bi (NO3)3) 0.02 mol/l, yttrium nitrate (Y(NOi)s) 0.01
0.01 mol/l of iron nitrate (Fe(NOx)s) was dissolved in an aqueous solution containing 0.01 mol/l of iron nitrate (Fe(NOx)s).
．． After adding 1 mol/l aqueous solution and filtering the precipitate,
It was crystallized by firing at 800°C for 4 hours.

50 parts by weight of BiYIG synthesized by the above coprecipitation method and 50 parts by weight of a transparent binder of acrylate resin are kneaded into an ink, which is applied onto the glass transparent substrate 2a and sandwiched between the glass transparent substrate 2b. Possibly BrYI
A G layer 1 was formed.

Solenoids 3 were attached to the top and bottom of this three-layered board. This made it possible to apply a magnetic field of 100 oersted in the in-plane direction of the substrate. By applying a direct current to the solenoid 3 using the power source 4, a magnetic field was applied to the substrate having a three-layer structure consisting of the BiYIG layer 1 and the transparent substrates 2a and 2b. When light was applied perpendicularly to the substrate, the light was scattered and the substrate became opaque. ill! Even after cutting down to 4, this condition was maintained. Next, the power supply 4 causes the solenoid 3 to
When a 50 Hz attenuated alternating current was applied to the crystal and the voltage was gradually lowered, light scattering ceased and the crystal became transparent. Even if the power is turned off, it retains its state and has a memory property.

(Effect of the invention) Although the present invention is configured as described above, BiYI
By using the C layer, it is possible to switch between a transparent state and an opaque state. In addition, by using the Cosoton-Mouton effect, it is only necessary to apply a magnetic field in the in-plane direction of the substrate, and there is no need to use an expensive substrate with transparent electrodes, so manufacturing can be done at low cost.Also, since it has memory properties, it can be manufactured at a constant voltage. There is no need to apply it.

Applications of the magneto-optical element of the present invention include light-shielding glass,
Examples include optical switches, optical shutters, spatial light modulators, etc., but are not limited thereto.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an explanatory diagram showing the configuration of a magneto-optical element. 1...BiYIC, layers 2a, 2b...Transparent substrate 3...Solenoid 4...Power supply patent application Person Toppan Printing Co., Ltd. Representative Kazuo Suzuki Figure 1

Claims (2)

[Claims] (1) A magneto-optical element characterized in that a layer containing fine powder of bismuth-substituted yttrium iron garnet in a transparent resin binder is interposed between two transparent glass substrates. (2) The magneto-optical element according to claim (1), characterized in that fine powder of bismuth-substituted yttrium iron garnet synthesized by a coprecipitation method is used.