JPH0875799A - Liquid crystal electric field sensor - Google Patents

Abstract

PURPOSE: To provide a liquid crystal electric field sensor capable of detecting electric field regardless of electric field direction. CONSTITUTION: In the liquid crystal electric field sensor using a liquid crystal 62 scattered in a polymer 6<1> , optical fibers 11 and 12 face to face are fixed on a base 4 surface and between the ends of the optical fibers 11 and 12 face to face, the liquid crystal 62 scattered in the polymer 6<1> is arranged. Thus, a high density measurement of electric field distribution is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal electric field sensor, and more particularly to a liquid crystal electric field sensor capable of detecting the electric field regardless of the direction of the electric field.

[0002]

2. Description of the Related Art A conventional example of a liquid crystal electric field sensor will be described with reference to FIG. FIG. 5 is a view showing a cross section of a conventional example of a liquid crystal electric field sensor. In FIG. 5, reference numeral 1 is an optical fiber, and 2 is a rod lens attached to the tip of the optical fiber 1.
If a light source is connected to the other end of the optical fiber 1 _1, a light receiver is connected to the other end of the optical fiber 1 ₂ . 3 is a polarizing plate, 4 is a transparent substrate, 5 is an alignment film formed on the surface of the transparent substrate 4, 6 is a liquid crystal layer enclosed between a layer of the alignment film 5 _{1 and} a layer of the alignment film 5 _2. is there. The liquid crystal molecules in the liquid crystal layer 6 have a structure aligned in the alignment direction defined by the alignment film formed on the surface of the transparent substrate 4. Parallel orientation, HAN (Hybr
id Aligned Nematic) orientation, VAN
(Vertical Aligned Nemat
ic) Orientation and other structures can be adopted.

In the liquid crystal electric field sensor as described above, the light emitted from the light source connected to the other end of the optical fiber 1 ₁ is used as a rod lens 2 ₁ , a polarizing plate 3 ₁ , a transparent substrate 4 ₁ and an alignment film 5. Light incident on the liquid crystal layer 6 via ₁ and transmitted through the liquid crystal layer 6 is transmitted through the alignment film 5 ₂ , the transparent substrate 4 ₂ , the polarizing plate 3 ₂ , the rod lens 2 ₂ and the optical fiber 1 ₂ to the optical fiber 1 _2. Light is received by a light receiver connected to the other end of the. Here, when an electric field is applied to the liquid crystal layer 6, the transmittance of light passing through the liquid crystal layer 6 changes because the liquid crystal molecules in the liquid crystal layer 6 try to align in the direction of the electric field. As the light transmittance of the liquid crystal layer 6 changes, the amount of light received by the light receiver decreases. The operation principle of the liquid crystal electric field sensor is as described above.

[0004]

In the conventional example of the liquid crystal electric field sensor illustrated and described with reference to FIG. 5, the liquid crystal molecules in the liquid crystal layer 6 are aligned in parallel, and the alignment direction of the liquid crystal molecules is uniform anywhere in the liquid crystal layer. , Parallel to the substrate surface. Here, FIG.
The relationship between the alignment direction of liquid crystal molecules and the direction of the applied electric field will be described with reference to FIG.

FIG. 6A shows the case where no electric field exists. When there is no electric field, the alignment direction of the liquid crystal molecules in the liquid crystal layer 6 does not change and remains unchanged. FIG. 6B shows the case where the electric field direction is orthogonal to the substrate surface. In this case, the alignment direction of the liquid crystal molecules in the liquid crystal layer 6 changes due to the application of the electric field. FIG. 6C shows the case where the electric field direction is parallel to the substrate surface. In this case, even if an electric field is applied, no change occurs in the alignment direction of the liquid crystal molecules in the liquid crystal layer 6.

The conventional example of the liquid crystal electric field sensor as described above is
Even if an electric field is applied to the liquid crystal layer 6, this may not be detected depending on the direction of application. This also applies to VAN orientations other than the parallel orientation. Also, if via the optical fiber Another problem input and output of light is required to very precisely properly positioning and fixing the optical fiber 1 _1, 1 ₂ mutually can lead to difficulties in the manufacture of liquid crystal electric field sensor Can be given. Further, because the rod lens must be held, even if many rod lenses are installed at extremely small intervals and the electric field is measured by detecting the electric field at each small interval, there is a problem that the installation is limited. is there.

The present invention provides a liquid crystal electric field sensor for detecting an electric field applied regardless of the direction of the electric field applied to the liquid crystal, and enables easy manufacture and high density measurement of the electric field distribution. .

[0008]

A liquid crystal electric field sensor characterized by using a liquid crystal 6 ₂ dispersed in a polymer 6 ₁ was constructed. Then, the optical fiber 1 ₁ facing each other
A liquid crystal electric field sensor having the above-mentioned elements 1 and ₂ and having the liquid crystal 6 ₂ dispersed in the polymer 6 ₁ is arranged between the ends of the optical fibers facing each other.

Further, the optical fibers 1 ₁ and 1 ₂ are fixed to the surface of the substrate 4 in a state of facing each other, and the optical fibers 1 facing each other are fixed.
The liquid crystal 6 ₂ which is dispersed in a polymer 6 in ₁ to constitute a liquid crystal electric field sensor disposed between the ₁ and 1 ₂ of the end. Further, a liquid crystal electric field sensor having a plurality of pairs of the optical fibers 1 ₁ and 1 ₂ facing each other and the liquid crystal 6 ₂ arranged between the ends of the optical fibers is also configured.

[0010]

EXAMPLES The present invention relates to a liquid crystal (Polymer Dispersed Liquid) dispersed in a polymer.
id Crystal, PDLC). PDL
Liquid crystal molecules in C are not subjected to alignment treatment
Arranged randomly in C. That is, PDLC
There is no directivity in the alignment direction of the liquid crystal molecules inside. Therefore, when an electric field is applied to the PDLC, the liquid crystal molecules randomly arranged in the PDLC are always deflected and aligned in the direction of the applied electric field, regardless of the direction of the applied electric field. . Due to this change in the alignment direction of the liquid crystal molecules, the amount of scattering of light passing through the PDLC changes,
The electric field can be detected regardless of the electric field direction.

An embodiment of the present invention will be specifically described below with reference to FIG. In this embodiment, the PDLC 6 is held by the transparent substrate 4 ₁ and the transparent substrate 4 ₂ . PDLC6 is
It can be constituted by dissolving a polymer 6 ₁ such as polyvinyl alcohol in water or another solvent and mixing it with the liquid crystal 6 ₂ to form a thin film by spin coating, and evaporating the solvent. PDLC6 is also a polymer 6
After sealed between the _first transparent substrate 4 ₁ which a photosensitive resin and a liquid crystal 6 ₂ mixed opposite is the transparent substrate 4 _2, by polymerizing a photosensitive resin by irradiating with light Can be configured.

2 and 3 are views for explaining another embodiment. In this embodiment, it is not necessary to form the PDLC 6 and the liquid crystal electric field sensor can be manufactured very easily. First, referring to FIG. 2, 7 is a substrate 2
A V groove formed on the surface, the optical fiber 1 ₁ and the optical fiber 1 ₂ faces constituting the fitting fixed state to the V groove 7. This can be easily realized by fixing one optical fiber to the V groove 7 formed in the substrate 2 with an adhesive and then cutting this one optical fiber with a blade. Reference numeral 8 is a rectangular groove formed orthogonal to the V groove 7. A Si substrate can be adopted as the substrate 2, and the V groove 7 can be formed by etching the Si substrate. Also, V
Since the groove 7 is not required to have high accuracy, the V-groove substrate 2 can be formed by using a material other than the Si substrate.

[0013] Next, referring also to FIG. 3, to place the liquid crystal PDLC6 dispersed in a polymer in a rectangular groove 8 between the opposite ends of the optical fibers 1 ₁ and the optical fiber 1 _second ends . This is the opposite optical fiber 1 in FIG.
Was added dropwise a mixed solution consisting of uncured liquid crystal polymer between the _first end and the optical fiber 1 _second ends, curing by evaporation or photocuring, or a solvent by light irradiation the polymer Then, the liquid crystal electric field sensor can be constructed.

In the above-described embodiment, there is one pair of liquid crystal arranged between the end portions of the optical fiber and the optical fiber facing each other. However, a plurality of pairs of these liquid crystals are formed on one substrate. Can be configured. By doing so, it is possible to measure the electric field distribution over a wide range. FIG. 4 is a diagram showing that the liquid crystal electric field sensor of the present invention can detect an electric field regardless of the electric field direction. FIG.
(A) is a diagram showing a case where no electric field is applied,
The liquid crystal molecules in the liquid crystal 6 ₂ dispersed in the polymer 6 ₁ remain randomly aligned. FIG. 4 (b) is a diagram showing a case where an electric field in a direction orthogonal to the substrate plate surface is applied, in which the liquid crystal molecules in the liquid crystal 6 ₂ dispersed in the polymer 6 ₁ are oriented in the direction of the applied electric field. Has been. FIG. 4C is a diagram showing a case where an electric field in a direction parallel to the substrate plate surface is applied, and the liquid crystal molecules in the liquid crystal 6 ₂ dispersed in the polymer 6 ₁ are the same as those in the case of FIG. 4B. It is oriented in the direction of the electric field applied to. In any case,
The liquid crystal molecules are necessarily deflected and aligned in the direction of the applied electric field, and the amount of light transmitted through the PDLC changes due to the change in the alignment direction of the liquid crystal molecules. It is shown that the electric field can be detected without the need.

The liquid crystal electric field sensor according to the present invention as described above is suitable for application to voltage monitoring and EMC detection in power transmission and distribution equipment.

[0016]

As described above, the liquid crystal electric field sensor of the present invention can detect the applied electric field regardless of the direction of the electric field applied to the liquid crystal. And
In particular, the other embodiment is easy to manufacture the liquid crystal electric field sensor. Further, by forming a pair of liquid crystals arranged between opposing optical fibers and end portions of the optical fibers on a plurality of one-to-one substrate, it is easy to measure the distribution of the electric field over a wide range.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example.

FIG. 2 is a diagram illustrating another embodiment.

FIG. 3 is a diagram of FIG. 2 viewed from above.

FIG. 4 is a diagram for explaining the operation of the embodiment.

FIG. 5 is a diagram illustrating a conventional example.

FIG. 6 is a diagram illustrating an operation of a conventional example.

[Explanation of symbols]

1 ₁ Optical Fiber 1 ₂ Optical Fiber 2 ₁ Rod Lens 2 ₂ Rod Lens 3 ₁ Polarizing Plate 3 ₂ Polarizing Plate 4 Substrate 4 ₁ Transparent Substrate 4 ₂ Transparent Substrate 5 ₁ Alignment Film 5 ₂ Alignment Film 6 Liquid Crystal Layer 6 ₁ Polymer 6 ₂ Liquid crystal 7 V groove 8 Rectangular groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuya Miyashita 1-21-6 Dogenzaka, Shibuya-ku, Tokyo Japan Aviation Electronics Industry, Ltd.

Claims (4)

[Claims] 1. A liquid crystal electric field sensor comprising a liquid crystal dispersed in a polymer. 2. The liquid crystal electric field sensor according to claim 1, wherein the liquid crystal electric field sensor is provided with opposing optical fibers, and liquid crystal dispersed in a polymer is disposed between the end portions of the opposing optical fibers. Liquid crystal electric field sensor. 3. The liquid crystal electric field sensor according to claim 2, wherein the optical fibers are fixed to the substrate surface while facing each other, and the liquid crystal dispersed in the polymer is arranged between the ends of the facing optical fibers. A liquid crystal electric field sensor characterized in that 4. The liquid crystal electric field sensor according to claim 2, wherein there are a plurality of pairs of liquid crystals arranged between the opposing optical fibers and the ends of the optical fibers. And liquid crystal electric field sensor.