JP2003270668A - Liquid crystal switch and optical modulating element for optical communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal switch which realizes exact light modulation control or deflection control without bringing about diffused reflection due to laser light and to provide a manufacturing method therefor and an optical modulating element (for communication) using the same. <P>SOLUTION: Two transparent substrates which have transparent conductive films formed on surfaces thereof and have liquid crystal alignment layers formed on the transparent conductive films are arranged so that the liquid crystal alignment layers may face each other, and a liquid crystal which horizontally aligns the alignment layer formed on one transparent substrate in one direction and horizontally aligns the alignment layer formed on the other transparent substrate in a direction opposite to the alignment direction of the alignment layer on one transparent substrate and satisfies Δn≥0.2 and 1.5≤Δn×d≤4 (d is the distance (mm) between two transparent substrates) is sealed in a seal part 2 provided with an outward extended projecting part 2a in the vicinity of a liquid crystal injection aperture between the substrates. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device for communication which is required not to scatter light, and more particularly to a liquid crystal switch and a light modulating device for communication using a laser beam.

[0002]

2. Description of the Related Art As a conventional communication liquid crystal switch, an element in which liquid crystal is arranged between two glass substrates has been used as a normal TN type liquid crystal display.

The communication liquid crystal switch can arrange a liquid crystal between two transparent substrates to change the degree of linear polarization of incident laser light.

Further, in the liquid crystal light modulating element for communication, the two liquid crystal switches are stacked and used as a set, and the circularly polarized light of the laser light incident on the first liquid crystal switch of the switch is converted into the linearly polarized light, Alternatively, by modulating the wavelength of the laser light, the second
By applying a voltage to the liquid crystal switch, the emitting direction of the laser light emitted from the second liquid crystal switch can be changed.

Since the diameter of the laser beam incident on the above light modulation element is 1 mm or less, the area on which the laser is incident may be small. Therefore, in order to further miniaturize the light modulation device, the size of the liquid crystal switch itself. Is desired to be small.

By the way, in a liquid crystal element in which a liquid crystal of a conventional technique used for displaying characters having a size of, for example, 10 mm in length and 30 mm in width is filled with a liquid crystal as a display area, the area between the transparent substrates is relatively large. It was not so difficult to fill the liquid crystal in the space surrounded by the liquid crystal seal provided in the above. The distance (gap) between the transparent substrates such as two glass plates forming a sealed space after the liquid crystal is sealed is maintained by interposing glass or resin spheres (spacers) therein. It was

[0007]

As described above, the conventional liquid crystal switch is manufactured by sealing the liquid crystal between the transparent substrates, and is used for the display element for keeping the thickness of the liquid crystal layer constant. When the spacers used are used, the incident laser is scattered by the spacers, and there is a problem that strict light modulation control or deflection control cannot be performed.

Further, when the sealed space of the liquid crystal element is reduced to, for example, about 1 cm square or less, the sealant provided in the liquid crystal injection port for injecting and sealing the liquid crystal into the sealed section mixes with the liquid crystal or has a gap. There is a problem that it is difficult to keep constant in each part of the sealed space. Above all,
It was difficult to manufacture a liquid crystal display without using spacers that are not uneven depending on the location in the sealed space.

An object of the present invention is to use a liquid crystal switch capable of performing precise light modulation control or deflection control without irregular reflection due to laser light, especially a small size liquid crystal switch, its manufacturing method, and the liquid crystal switch. An object of the present invention is to provide a light modulation element.

[0010]

The above-mentioned problems of the present invention can be solved by the following constitutions (1), (2) and (3). (1) Two transparent substrates, each having a transparent conductive film formed on its surface and a liquid crystal alignment film formed on the transparent conductive film, are arranged so that the liquid crystal alignment films face each other, and a positive electrode is provided between the substrates. In a liquid crystal switch in which a liquid crystal having a dielectric anisotropy is sealed and a voltage is applied between the transparent conductive films to control the transmittance of input light, a difference in refractive index between normal light and extraordinary light is used as the liquid crystal. n, and the distance between the transparent substrates is d
(Mm), the value of Δn · d is 1.5 ≦ Δn · d
≦ 4, and when no voltage is applied, the liquid crystal alignment film formed on one transparent substrate is horizontally aligned in one direction, and the liquid crystal alignment film formed on the other transparent substrate is aligned in the liquid crystal alignment film of the one transparent substrate. A liquid crystal switch that is horizontally aligned in the opposite direction.

Since the liquid crystal alignment films formed on the two transparent substrates are horizontally aligned in opposite directions to each other, all liquid crystals existing in the thickness direction of the liquid crystal layer (direction between the substrates) are surely aligned in a fixed direction. It is possible to obtain the action and effect. The angle deviation θ of the horizontal orientation is preferably ± 2 degrees or less. If it exceeds this range, there is a problem that the light transmittance upon application of a voltage is lowered, and a discontinuous portion is generated in the array, which is not preferable. It is more preferable that θ be ± 0.5 degrees or less.

The horizontal orientation in the positive direction has a disadvantage that a discontinuous alignment occurs in the liquid crystal layer.

Further, the distance between the two transparent substrates is d (m
m), the value of Δn · d is 1.5 ≦ Δn · d ≦ 4
However, if the value of Δn · d is less than 1.5, the control range of optical wavelength modulation becomes narrow, which is not preferable. Further, if the value of Δn · d exceeds 4, the response speed for vertically aligning the liquid crystal and the switching speed of the liquid crystal decrease, which is not preferable. A preferred switching speed for using the present invention as a device for switched optical communication using laser light is about 1 msec.

Further, the liquid crystal is made of nematic liquid crystal or cholesteric liquid crystal, and it is desirable that the difference Δn in refractive index between normal light and extraordinary light is 0.2 or more. By setting the refractive index difference Δn between the normal light and the extraordinary light of the liquid crystal to be 0.2 or more, it is possible to obtain an effect that Δn · d can be increased without increasing the gap. Preferably 0.25
That is all.

Distance d (gap) between two transparent substrates
Is secured by a seal portion having a liquid crystal injection opening made of resin provided in the peripheral portion between the substrates for sealing the liquid crystal between the substrates, and the seal portion is directed to the outside in the vicinity of the opening. Providing an overhang is desirable.

Due to the contraction of the resin that occurs when the liquid crystal injection opening is sealed with the resin, the gap changes near the injection port. This warpage locally reduces the distance (gap) between the substrates in the liquid crystal enclosed space (liquid crystal switch operating unit). When the gap fluctuates, the magnitude of wavelength modulation or deflection varies depending on the location. The resin encapsulant does not enter the inside due to the presence of an outwardly protruding portion provided near the opening, or the liquid crystal expands due to the heat received during UV irradiation before the resin encapsulant is cured by UV, and the resin encapsulant is sealed. There is a problem that the phenomenon of return of the stopper (the sealant goes out of the seal part) occurs.

Further, it is preferable that the projecting portion toward the outside of the liquid crystal injection opening has a shape in which the opening width becomes narrower toward the outside, and a stopper is provided at approximately the center in the width direction.

Since the opening width of the projecting portion toward the outside of the liquid crystal injection opening is narrowed toward the outside and the stopper is provided at substantially the center in the width direction, the resin encapsulant is provided inside. It will not invade and mix with the liquid crystal.

The length in the width direction of the liquid crystal injection opening is w (m
m) and the length of the side of the seal portion where the liquid crystal injection opening is provided is W (mm): 0.5 ≦ w ≦ 2.0 w / W ≦ 0.1 5 ≦ W ≦ 10 It is desirable to have a relationship.

If the dimension w in the width direction of the liquid crystal injection opening and the length W of the side of the seal portion of the liquid crystal filling space where the liquid crystal injection opening is provided have the above-mentioned relationship, bubbles will be generated in the small liquid crystal sealed space. It is possible to fill and inject the liquid crystal more surely and quickly without causing the occurrence. Further, it is possible to prevent the resin for filling the liquid crystal injection opening from entering the inside during the sealing.

If the width w of the liquid crystal injection opening is less than 0.5 mm, it takes too much time to inject the liquid crystal. Further, when the width w of the liquid crystal injection opening exceeds 2 mm, the sealant enters too much from the liquid crystal injection opening, which causes uneven light modulation when a laser is applied to the liquid crystal.

If the w / W exceeds 0.1, it becomes difficult to draw in the sealant at the opening, and if the seal is thin, liquid crystal leakage occurs.

If the length W of the side of the seal portion provided with the liquid crystal injection opening is less than 5 mm, the effective area for light irradiation and light modulation becomes small, and if W exceeds 10, the spacer is not used. Without it, it becomes difficult to maintain the gap while suppressing the light scattering.

Further, it is desirable to form one or more protrusions on the sides of the seal portion, the protrusions extending outward from the sides of the seal portion. In particular, it is more preferable to provide it on the side opposite to the part having the liquid crystal injection opening (on the side where the external connection pin is attached to the terminal).

The protrusion prevents the center portion of the cell of the seal portion opposite to the portion having the opening from being depressed due to the curing shrinkage of the UV curable resin, and has the effect of preventing the variation of the gap between the transparent substrates. In this way, since the gap between the transparent substrates can be kept uniform over the entire substrate without inserting a spacer, the scattering loss of the incident laser light can be reduced.

(2) The two liquid crystal switches are arranged in parallel so as to be stacked in parallel, and the horizontal alignment direction of the liquid crystal of the first liquid crystal switch and the horizontal alignment of the liquid crystal of the second liquid crystal switch when no voltage is applied. A light modulation element in which the angle formed by the directions is approximately 45 degrees.

The first liquid crystal switch can change the incident light into a circularly polarized light into a linearly polarized light, adjust the wavelength and the wavelength according to the applied voltage, and the second liquid crystal switch can change the outgoing direction of the output light. it can.

In this way, the light modulation element of the present invention can perform wavelength modulation and deflection of the wavelength of the laser light, and can increase communication variations.

By making the angle between the horizontal alignment direction of the liquid crystal of the first liquid crystal switch and the horizontal alignment direction of the liquid crystal of the second liquid crystal switch approximately 45 degrees, the light modulation can be effectively performed.

(3) After forming a transparent conductive film on the surfaces of two transparent substrates, a liquid crystal alignment film is formed on the transparent conductive film, and the liquid crystal alignment film on one transparent substrate is unidirectionally applied when no voltage is applied. Horizontally, the liquid crystal alignment film of the other transparent substrate is horizontally aligned in the direction opposite to the alignment direction of the liquid crystal alignment film of the one transparent substrate, and then the liquid crystal is applied to at least one of the two transparent substrates. A seal portion having an injection opening is formed, the two transparent substrates are attached to each other to define a liquid crystal sealed space, and a liquid crystal having a positive dielectric anisotropy is provided between the liquid crystal injection port and the substrate. A method for manufacturing a liquid crystal switch to be sealed.

As described above, since the liquid crystal alignment films formed on the two transparent substrates are horizontally aligned in the opposite directions to each other, all liquid crystals existing in the thickness direction of the liquid crystal layer (direction between the substrates) can be surely directed in a fixed direction. The effect of being able to orient the film is obtained. The angle deviation θ of the horizontal orientation is preferably ± 2 degrees or less. If the deviation θ exceeds this, there is a problem that the light transmittance upon application of a voltage decreases, and a discontinuous portion occurs in the array, which is not preferable. The deviation θ is more preferably ± 0.5 degrees or less. The reason why the horizontal orientation is the positive orientation is that a disadvantage that discontinuous alignment occurs in the liquid crystal layer occurs.

Further, the horizontal alignment process for making the alignment films of the two transparent substrates in mutually opposite directions is performed by a rubbing process,
It is desirable to press a cloth that rotates in the rubbing direction in the opposite direction. Among the many alignment treatment methods, by adopting a rubbing treatment method in which a lathe cloth is wrapped around a cylindrical rotating body and is rubbed while rotating the rotating body, it is possible to surely and substantially uniformly form a directional groove on an alignment film such as polyimide. There is an advantage that can be attached.

Further, since the cross-sectional area of the liquid crystal injecting opening of the seal portion is formed so as to increase toward the inside of the liquid crystal hermetically sealed space, it is possible to prevent the transparent substrate from warping.

Further, at the same time as the formation of the seal portion, a stopper is formed outside the inner line of the seal portion and inside the outer portion of the liquid crystal injecting opening substantially at the center in the width direction so that the liquid crystal injected into the seal portion is prevented. There is no risk of leakage to the outside of the seal.

Further, the liquid crystal is sealed by applying pressure to the transparent substrate to reduce the distance between the transparent substrates, applying liquid crystal sealing resin to the liquid crystal injection opening under the pressure, and applying the liquid crystal to the transparent substrate. By sequentially passing through the steps of reducing the pressure and hardening the liquid crystal sealing resin, it is possible to reliably fill and inject the liquid crystal sealed space having a small size without generating bubbles.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

First, a method of manufacturing the liquid crystal switch will be described with reference to FIG. Step 1. Preparation of glass plate with transparent conductive film: 700Ω /
A 0.7 mm thick glass plate (7059 glass manufactured by Corning Co., Ltd.) coated with a square ITO transparent conductive film was prepared.

Step 2. Patterning of ITO electrode: I
The TO transparent conductive film was formed into an electrode by a photolithography method using an etching aqueous solution containing hydrochloric acid as a main component in a predetermined shape to obtain a transparent substrate.

Step 3. Formation of liquid crystal alignment film: A polyimide precursor solution is applied to the surface on which the ITO electrode is formed,
It was heated at 0 ° C. for 30 minutes to form a polyimide polymer film. For the liquid crystal alignment film, a method of forming a groove in a certain direction on the surface of the polyimide film by pressing while rotating and moving a rotating body of a black Rasha cloth wound on the surface of the polyimide film was adopted. Alignment treatment with strong anchoring (regulatory force of the alignment film against the liquid crystal) (shown as “strong” in Table 1) increases the rotational speed of the rotating body by 17
430 as an example of weak anchoring (indicated as “weak” in Table 1) at 1 rpm at 00 rpm and 10 mm / sec.
It was carried out at 1 scan for 30 seconds at rpm. Two glass substrates with the alignment film formed were prepared for four types of liquid crystals.
Liquid crystals A to D are all nematic liquid crystals, and are shown in Table 1.
A prototype was used so as to have Δn shown in.

Step 4. Formation of seal part: Epoxy resin (trade name: Struct Bond XN-21S manufactured by Mitsui Toatsu Chemicals, Inc.) was printed on one glass substrate in a predetermined shape by a screen printing method. As shown in the plan view of FIG. 1, by screen printing, a seal portion 2 having a liquid crystal injection opening for hermetically partitioning the liquid crystal in one glass substrate 1 and a protruding portion 2a narrowing outward and a stopper. 3 were printed simultaneously. The width w of the liquid crystal injection opening is 1.
Since the length of the side of the seal portion in which the liquid crystal injection space of the liquid crystal filled space is 25 mm is set to 25 mm and the width w1 of the seal is set to 1.0 mm, bubbles are generated in the liquid crystal sealed space having a small size. The filling and injecting can be performed more surely and quickly without using. Further, a pair of protrusions 2b is provided on the long side opposite to the side of the seal portion 2 having the liquid crystal injection opening. In this manner, the protrusion 2a and the pair of protrusions 2b that become narrower toward the outside eliminate warpage of the seal portion 2, and the uniformity of the gap between the substrates can be maintained without providing a spacer between the substrates.

Step 5. Bonding: Two glass substrates were bonded together via the seal part 2, and the seal member was heated and cured at 150 ° C. for 90 minutes to obtain a liquid crystal cell having a liquid crystal sealed section. The distance between the substrates of the liquid crystal cell is 11.5 μm
And

Step 6. Liquid crystal injection: this step 6. 6. Liquid crystal injection and the next step 7. The liquid crystal is sealed under the pressurized and depressurized conditions shown in FIG. First, the liquid crystal filled in the liquid crystal dish in a container capable of depressurizing was sucked up and injected into the liquid crystal cell by a known method. The liquid crystal used is a nematic liquid crystal of four types A to D having a refractive index Δn of 0.20 to 0.25 as shown in Table 3.

Step 7. Liquid crystal encapsulation: Remove the liquid crystal cell from the depressurizable container, apply external pressure from one substrate to reduce the distance between the substrates, and in that state UV curable resin Chemitech Co., Ltd. trade name: ChemiSeal 5X009 Was applied to the opening for liquid crystal injection. The resin was polycondensed and cured by ultraviolet rays with a part of the external pressure being released. After that, the external force was completely removed.

Step 8. External Input Metal Pin Installation:
3A is a plan view of the liquid crystal switch including a plane having the seal portion 2 of FIG. 3A, and FIG. 3A is a view taken along the line AA of FIG. 3A.
As shown in the side sectional view of the liquid crystal switch of (b), a pair of metal pins 9 and 10 for applying a voltage from the outside between two transparent electrodes are attached to a glass plate by using an ultraviolet curable resin by adhesion. And the external dimension of the liquid crystal switch is 10m
A liquid crystal switch of m × 7.5 mm × 1.4 mm was produced. One metal pin 9 is connected to the switch electrode 16 via the wiring electrode 5 of the substrate 4, and the other metal pin 10 is wired from the wiring electrode 6 on the transparent substrate 4 via the conductive paste 7 to the wiring (not shown) of the substrate 1. Connect the electrode to the switch electrode.
The electrode forming portion of this liquid crystal switch has a size of 6 mm × 2.
It was 0 mm. Table 1 shows the obtained liquid crystal physical property values. Table 2 shows the values of the gap d and Δn · d between the glass plates of the liquid crystal switch cell obtained by using the liquid crystals A to E.

[0045]

[Table 1]

[Table 2]

Example 1 Using liquid crystal A shown in Table 1, the above steps 1 to 8 were carried out.
A liquid crystal switch was produced. This liquid crystal switch had a uniform value with a glass substrate distance of 11.5 μm throughout, and the value of Δn · d was 2.31 as shown in Table 2. As described above, in the seal portion 2 of the present invention, the projecting portion 2a (protruding portion 2) extending outward in the vicinity of the liquid crystal injection opening is formed.
b) is provided, and due to the shape of the seal portion 2, the inter-substrate distance becomes uniform without the occurrence of optical interference fringes due to the nonuniformity of the gap at the time of sodium lamp light irradiation on the cell surface. When a laser having a diameter of 60 μm and a wavelength of 1.55 nm and an output of 0.5 W was made incident and the degree of linearly polarized light was measured by changing the position of the incident light, a modulation characteristic of the light wavelength was obtained.

Example 2 Using the liquid crystal B shown in Table 1, the above steps 1 to 8 were carried out.
A liquid crystal switch was produced. This liquid crystal switch has a uniform value with a substrate-to-substrate distance of 11.5 μm throughout, and Δ
n · d was 2.79 as shown in Table 2. Diameter 60
When a laser having a wavelength of 1.55 nm and an output of 0.5 W was incident and the degree of linearly polarized light was measured by changing the position of the incident light, the same modulation characteristic of the light wavelength as in Example 1 was obtained.

Example 3 Using the liquid crystal C shown in Table 1, the above steps 1 to 8 were repeated.
A liquid crystal switch was produced. This liquid crystal switch has a uniform value with a substrate-to-substrate distance of 11.5 μm throughout, and Δ
n · d was 2.86 as shown in Table 2. Diameter 60
When a laser having a wavelength of 1.55 nm and an output of 0.5 W was incident and the degree of linearly polarized light was measured by changing the position of the incident light, the same modulation characteristic of the light wavelength as in Example 1 was obtained.

Example 4 Using liquid crystal D shown in Table 1, the above steps 1 to 8 were carried out.
A liquid crystal switch was produced. This liquid crystal switch has a uniform value with a substrate-to-substrate distance of 11.5 μm throughout, and Δ
n · d was 2.92 as shown in Table 2. Diameter 60
When a laser having a wavelength of 1.55 nm and an output of 0.5 W was incident and the degree of linearly polarized light was measured by changing the position of the incident light, the same modulation characteristic of the light wavelength as in Example 1 was obtained.

Example 5 An optical modulator including the two liquid crystal switches produced in Example 1 as a set was produced. In this light modulation element, as shown in FIG. C4, the first liquid crystal switch 13 and the second liquid crystal switch 14 are placed in such a positional relationship that the horizontal alignment direction of the liquid crystal is approximately 45 degrees when no voltage is applied to each. It was manufactured by laminating so that This light modulator has a diameter of 6
A laser with an output of 0.5 W having a wavelength of 1.5 μm and a wavelength of 0.5 μm was made incident from the first liquid crystal switch 14 side, and the wavelength and the emission direction of the laser light emitted from the second liquid crystal switch were examined. It was confirmed that by changing the voltage applied to the first liquid crystal switch 14, the circularly polarized light can be changed to linearly polarized light and its wavelength or phase can be changed. Moreover, it was confirmed that the light emission direction was changed by changing the voltage applied to the second liquid crystal switch 14.

Example 6 As shown in Table 1, a liquid crystal E (Δn
= 0.139, product name: Asahi Denka Kogyo KK: ADK-9
No. 051C) was used and the distance between the substrates was 7 μm, and the above Step 1 was performed in the same manner as in Example 1.
The liquid crystal switch was produced by This liquid crystal switch had a uniform value with a substrate-to-substrate distance of 7 μm throughout, though the size of the liquid crystal switch was small.
That is, when the glass surface was irradiated with sodium lamp light, optical interference fringes due to the nonuniformity of the gap were not observed on the cell surface.

Comparative Example 1 A liquid crystal switch was manufactured by the above steps 1 to 8 in the same manner as in Example 1 except that the seal portion 2 having no protruding portion 2b was formed as a seal for hermetically partitioning the liquid crystal. . When the glass surface of this liquid crystal switch was irradiated with sodium lamp light, interference fringes were visually recognized and the gap was nonuniform (it was concave). This LCD switch has a diameter of 6
When a laser of 0 μm and a wavelength of 1.55 nm and an output of 0.5 W was made incident and the degree of linearly polarized light was measured by changing the position of incident light, it was found that the characteristics of light modulation varied depending on the incident position. It is considered that this is because the distance between the substrates was not uniform as a whole because the seal portion 2 did not have the protruding portion 2b.

[0053]

According to the present invention, it is possible to obtain a liquid crystal switch capable of strict wavelength modulation control or deflection control of light without causing irregular reflection by laser light and a light modulation element using the liquid crystal switch. .

[Brief description of drawings]

FIG. 1 is a plan view of a seal portion provided on a transparent substrate in a liquid crystal switch manufacturing process of the present invention.

FIG. 2 is a program for producing a liquid crystal switch of the present invention.

3 is a plan view (FIG. 3A) of a surface including a seal portion of the liquid crystal switch of the present invention and a sectional view taken along line AA of FIG. 3A (FIG. 3B).

FIG. 4 is a structural diagram of a light modulation element of the present invention.

FIG. 5 is a diagram showing how the liquid crystal sealing pressure is controlled on the seal portion of the liquid crystal switch of the present invention.

FIG. 6 is a diagram showing a rubbing direction of the liquid crystal of the present invention.

[Explanation of symbols]

1 Transparent substrate 2 Seal part 2a Overhang part 2b Projection part 3 Stopper 4 Transparent substrate 5, 6 Wiring electrode 7 Paste 9, 10 Metal pin 13, 14 Liquid crystal 15 Beam splitter 16 Switch electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihiro Morito             7 nano at 6 Nagasaki, Okajima, Fukushima City, Fukushima Prefecture             X Co., Ltd. F term (reference) 2H088 EA44 EA45 EA47 FA04 GA02                       GA03 HA01 HA02 HA03 JA04                       KA01 KA06 KA07 LA07 MA17                       MA20                 2H089 LA22 LA28 LA29 LA35 MA03Y                       MA03Z NA41 NA44 NA48                       QA11 QA14 QA16 RA04 SA03                       SA04 TA01 TA02 TA04 UA09                 2H090 HA11 HB08Y HC05 HD14                       JB02 KA04 LA02 LA03 MA02                       MA06 MB01

Claims (10)

[Claims] 1. A transparent conductive film is formed on a surface of the transparent conductive film, and two liquid crystal alignment films are formed on the transparent conductive film. The two transparent substrates are arranged so that the liquid crystal alignment films face each other. In a liquid crystal switch in which a liquid crystal having a positive dielectric anisotropy is enclosed and a voltage is applied between the transparent conductive films to control the modulation of input light, the liquid crystal has a difference in refractive index between normal light and extraordinary light. △ n
And the distance between the transparent substrates is d (mm), Δn
・ The value of d is 1.5 ≦ Δn · d ≦ 4, and when no voltage is applied, the liquid crystal alignment film formed on one transparent substrate is horizontally aligned in one direction, and the liquid crystal alignment formed on the other transparent substrate. A liquid crystal switch, wherein the film is horizontally aligned in a direction opposite to the alignment direction of the liquid crystal alignment film on the one transparent substrate. 2. The liquid crystal switch according to claim 1, wherein the liquid crystal is a nematic liquid crystal or a cholesteric liquid crystal. 3. The distance between the two transparent substrates is ensured by a sealing portion having a resin-made liquid crystal injection opening provided in a peripheral portion between the substrates for sealing liquid crystal between the substrates, 2. The seal portion is provided with an outwardly projecting portion in the vicinity of the opening.
Or the liquid crystal switch described in 2. 4. The protruding portion extending outward of the liquid crystal injection opening has a shape in which the opening width narrows outward, and a stopper is provided at substantially the center in the width direction. The liquid crystal switch according to claim 4. 5. The length in the width direction of the liquid crystal injection opening is w (m
m) and the length of the side of the seal portion where the liquid crystal injection opening is provided is W (mm), 0.5 ≦ w ≦ 2.0 w / W ≦ 0.1 5 ≦ W The liquid crystal switch according to claim 3 or 4, characterized in that there is a relationship of ≤10. 6. The liquid crystal switch according to claim 1, wherein one or more protrusions are formed on the sides of the seal portion, the protrusions extending outward from the sides. 7. A liquid crystal switch according to claim 1, wherein two liquid crystal switches are arranged in parallel so as to be stacked in parallel, and a horizontal alignment direction of liquid crystal of the first liquid crystal switch when no voltage is applied and An optical modulation element characterized in that the angle formed by the horizontal alignment direction of the liquid crystal of the second liquid crystal switch is approximately 45 degrees. 8. A transparent conductive film is formed on the surfaces of two transparent substrates, and then a liquid crystal alignment film is formed on the transparent conductive films, and when no voltage is applied, the liquid crystal alignment film on one transparent substrate is oriented in one direction. Horizontally align the liquid crystal alignment film on the other transparent substrate horizontally opposite to the alignment direction of the liquid crystal alignment film on the one transparent substrate, and then inject liquid crystal into at least one transparent substrate of the two transparent substrates. A sealing portion having an opening for liquid crystal is formed, the two transparent substrates are attached to each other to define a liquid crystal sealed space by the sealing portion, and then a positive dielectric anisotropy is provided between the liquid crystal injection opening and the transparent substrate. A method of manufacturing a liquid crystal switch for sealing a liquid crystal, which comprises forming a cross-sectional area of the liquid crystal injection opening of the seal portion so as to increase toward an inner direction of the liquid crystal sealing space. 9. The stopper is formed at the same time as the formation of the seal portion, outside the inner line of the seal portion and at the inner side of the outer portion of the liquid crystal injection opening in the approximate center in the width direction. A method for manufacturing the described liquid crystal switch. 10. The hermetically sealing the liquid crystal, 1) a step of pressing a transparent substrate to reduce the distance between the transparent substrates, 2) a step of applying a liquid crystal sealing resin to the liquid crystal injection opening under the pressure, 3. The method of manufacturing a liquid crystal switch according to claim 8 or 9, wherein each step of 4) a step of reducing the pressure applied to the transparent substrate and 4) a step of curing the liquid crystal sealing resin is sequentially performed.